HomeMy WebLinkAboutGreen River Flood Control Zone District
RESOLUTION NO. 3 4 8 1
A RESOLUTION OF THE CITY COUNCIL OF THE CITY OF AUBURN,
WASHINGTON, AUTHORIZING THE MAYOR AND CITY CLERK TO
EXECUTE AN INTERLOCAL AGREEMENT BETWEEN KING COUNTY,
THE CITIES OF AUBURN, KENT, RENTON, AND TUKWILA RELATING
TO ADMINISTRATION OF THE GREEN RIVER FLOOD CONTROL
ZONE DISTRICT.
WHEREAS, the City of Auburn is engaged in various municipal functions
including interlocal agreements relating to flood control zones; and
WHEREAS, in order to provide for such services, it is appropriate that the Cities
of Auburn, Kent, Renton and Tukwila jointly participate in an Agreement; and
WHEREAS, in order to provide for those services, the Cities of Auburn, Kent,
Renton and Tukwila have negotiated an Agreement for the Green River Flood Control
Zone District for such services, and the Cities have determined that through this
Interlocal Agreement they will be able to provide the services necessary, in a manner
that is acceptable to the Cities.
NOW, THEREFORE, THE CITY COUNCIL OF THE CITY OF AUBURN,
WASHINGTON, HEREBY RESOLVES as follows:
Section 1. The Mayor and City Clerk are authorized to execute an agreement in
substantially conformity with the Agreement attached hereto, marked as Exhibit "A" and
incorporated herein by this reference.
Section 2. The Mayor is hereby authorized to implement such administrative
procedures as may be necessary to carry out the directives of this legislation.
Section 3. This resolution shall take effect and be in full force upon passage and
signatures hereon.
Resolution No. 3481
June 13, 2002
Page 1
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Dated and Signed this day of 2002.
CITY OF AUBURN
/
PETER B. LEWIS ~
MAYOR
ATTEST:
Da 'elle E. Daskam,
City Cierk
APPRQVED AS TO FORM:
dwii"Of B.H','
City Attorney
Resolution 3481
June 13, 2002
Page 2
INTERLOCAL AGREEMENT FOR
THE ADMINISTRATION OF THE
GREEN RIVER FLOOD CONTROL ZONE DISTRICT
PREAMBLE
THIS AGREEMENT ("AgreemenY') is entered into pursuant to Chapters 86.15 and 39.34 of the
Revised Code of Washington (RCW), by and between the municipal county and city
governments signing this Agreement, that are located in King County lying wholly or partially
within those areas of the lower Green River watershed that are within the boundaries of the
Green River Flood Control Zone District as shown in Appendix A(collectively the "Parties").
The Parties share interests and responsibility for addressing flood hazard reduction planning,
river facility project construction and repair, and maintenance and operation of critical flood
protection facilities within the lower Green River watershed, and wish to provide for planning,
funding and implementation of programs, activities and projects therein. The Parties have
actively participated in these interests and responsibilities through the Green River Basin
Program since its inception in 1978. In addition, in 1990 the Parties pledged their support for
activation of the Green River Flood Control Zone District by King County.
It is the purpose of this Agreement to extend and renew the principles embodied in the 1985
Green River Management Agreement and 1992 Green River Basin Program Interlocal
Agreement in order to provide a coordinated program for achieving the goals contained in these
two agreements. The Parties further agree that flood hazard reduction, flood warning and
emergency response, and integrated resource management is best achieved throughout the
approximately 68 square miles of the lower Green River basin through multi-jurisdictional
coordination as provided for in this Agreement.
The Green River Flood Control Zone District is a quasi-municipal corporation of the State of
Washington, authorized by Chapter 86.15 RCW, which provides a permanent and reliable
~ regional funding source to accomplish the following purposes: to repair and maintain flood
protection facilities; to operate and maintain pump stations in the lower Green River watershed;
~ to implement King County's comprehensive flood hazard reduction plan for the Green River
Flood Control Zone District; and to coordinate with federal, state and other local agencies for
f
July 2002 Page 1 of 17
floodplain management, disaster response, and the protection and restoration of habitat for
threatened and endangered salmonid species.
MUTUAL CONVENANTS AND AGREEMENTS
1. DEFINITIONS. For purposes of this Agreement, the following terms shall have the
meaning stated below:
1.1 JURISDICTIONS ("PARTIES"): The governments participating in this
- Agreement as Parties are the County of King and the Cities of Auburn, Kent,
Renton and Tukwila. Each of the Parties is a municipal corporation of the State
of Washington.
~ 1.2 BOARD OF SUPERVISORS: Pursuant to Chapter 86.15.050 RCW, the King
County Council members are the Board of Supervisors of the Green River Flood
~
Control Zone District.
1.3 EXECUTIVE COMMITTEE: The Executive Committee referred to herein is the
governing body responsible for providing advisory policy guidance and
recommendations under the terms of this Agreement, as more fully set forth in
Section 4.1 below. The membership of the Executive Committee shall consist of
the following: the mayors of the Cities of Auburn, Kent, Renton and Tukwila, the
King County Executive, and a King County Council member representing the
Board of Supervisors. The Executive Committee is responsible for reviewing and
providing recommendations on the Green River Flood Control Zone District's
annual budget and work program and other related matters as may come before
this Committee, and for providing recommendations on these matters, as
appropriate, to the Board of Supervisors.
1.4 TECHNICAL COMMITTEE: The Technical Committee referred to herein is the
cooperative body composed of the public works or department directors and/or
their designated representatives of each of the Parties, and any other persons
~ who are deemed by consensus of the Parties to be appropriate participants in
I addressing the cooperative administration of the Green River Flood Control Zone
4 District and its annual work Pro9ram and bud9et, as more fullY set forth in
Section 4.2 below. The Technical Committee is the body responsible for
recommending actions to the Executive Committee related to flood hazard
reduction planning and project implementation, and other basin-wide activities
~ July 2002 Page 2 of 17
directly related to the purposes of the Green River Flood Control Zone District
and the terms of this Agreement.
1.5 GREEN RIVER FLOOD CONTROL ZONE DISTRICT ("DISTRICT"): This
district is a quasi-municipal corporation and independent taxing district
authorized for the purposes contained in Chapter 86.15 RCW.
1.6 ADMINISTRATOR: Administrator, as used herein, means collectively the
employees, specialists, technicians, fiscal agents and other personnel supplied
by King County to and for the administration of the Green River Flood Control
Zone District in accordance with Chapter 86.15 RCW and the administration of
the activities and purposes undertaken pursuant to the terms of this Agreement.
1.7 AD VALOREM TAX LEVY: The ad valorem tax levy, which is based upon the
total assessed valuation of property within the District, is the revenue source
historically and currently used to fund the flood hazard reduction planning,
facilities operation and maintenance, and project and program implementation
within the Green River Flood Control Zone District.
2. PURPOSES. The purposes of this Agreement include the following:
2.1 Continue to provide a vehicle for interagency coordination and cooperation
among the Parties on flood hazard reduction planning, programs and projects
within the Green River Flood Control Zone District.
2.2 Continue to provide integrated policy and technical advisory input to the Green
River Flood Control Zone District through the Executive and Technical
Committees.
2.3 Develop and implement contemporary standards and procedures for operating,
maintaining and repairing river flood protection facilities and pump stations within
the Green River Flood Control Zone District to maximize public health and safety
that are consistent with the requirements of the federal Endangered Species Act
and other applicable federal, state and local laws and regulations.
2.4 Provide a coordinated interjurisdictional mechanism to: (a) more efficiently and
effectively implement flood hazard reduction measures and programs in the
Green River Flood Control Zone District; (b) cooperate with federal, state, local,
and other agencies and parties having jurisdiction and/or resources to support
enhanced flood hazard reduction in the Green River Flood Control Zone District;
and (c) coordinate and improve flood warning, emergency response and disaster
July 2002 Page 3 of 17
recovery with the Federal Emergency Management Agency, the U.S. Army
Corps of Engineers, the Washington State Emergency Management Division,
and, as appropriate, other federal, state and local agencies.
3. EFFECTIVE DATE AND TERM. This Agreement shall become effective upon its
execution by the five (5) eligible jurisdictions within and representing the geographic
areas comprising the Green River Flood Control Zone District, as authorized by each
jurisdiction's governing body. Upon the effective date, this Agreement shall remain in
effect for a term of ten (10) years; provided, however, that this Agreement may be
extended for any such additional terms as the Parties may agree to in writing, in
accordance with the Amendment provisions of Section 11 below.
4. ORGANIZATION AND RESPONSIBILITIES OF GREEN RIVER FLOOD CONTROL
ZONE DISTRICT. The Parties to this Agreement hereby agree to participate in and
promote the purposes of the Green River Flood Control Zone District and to establish an
Executive Committee as the governance structure for promoting and implementing the
purposes of this Agreement, and a Technical Committee for promoting and
implementing the purposes of this Agreement. These committees will be staffed by King
County, which is the Administrator of this Agreement, and which is also the Administrator
of the Green River Flood Control Zone, under the provisions of Chapter 86.15 RCW.
4.1 Green River Flood Control Zone District Executive Committee. The
Executive Committee shall:
4.1.1 Select from among its members a chairperson to chair the Executive
Committee and to oversee and conduct its annual meeting and any other
meetings that may be scheduled; select a vice-chairperson to perform the
functions of the chairperson in the event of the chairperson's absence;
and adopt rules and procedures for the Executive Committee's
operations.
4.1.2 Meet at least annually, no later than October 15 of each year, to review
the status of the then current year's flood reduction budget and work
program, and to make budget and work program recommendations for
the following calendar year. The Executive Committee shall forward their
budget and levy rate recommendations for the following year to the Green
River Flood Control Zone DistricYs Board of Supervisors no later than
July 2002 Page 4 of 17
October 31 of each year, and shall also make recommendations on other
program and financing proposals as may come before the Executive
Committee.
4.1.3 Adopt other rules and procedures necessary for the implementation of
this Agreement.
4.2 Green River Flood Contro/ Zone District Technical Committee. The
designated representatives of each of the Parties to the Technical Committee will
undertake the responsibilities identified immediately below. Representatives
from other municipalities and resource agencies may also participate in
Technical Committee meetings and activities based on consensus of the Parties
and on an as needed basis. The Technical Committee shall:
4.2.1 Meet at least six times per year and be responsible for the following
primary responsibilities and activities:
➢ Carry out the directives of the Executive Committee.
➢ Formulate and recommend the annual work program and budget for
the Green River Flood Control Zone District for consideration by the
Executive Committee.
➢ Establish and recommend the Green River Flood Control Zone District
annual repair and maintenance program priorities.
➢ Review all policy questions and technical issues relevant to the
annual work program and budget.
➢ Make recommendations to the Executive Committee on work program
and budget initiatives including revenue enhancements and the
annual levy rate for the Green River Flood Control Zone District.
➢ Review and coordinate all other matters that may come before the
Technical Committee.
4.2.2 Provide performance and peer review of existing technical work products
and plans and make recommendations for action, including initial
decisions related to the work program, service contracts, and budget and
financial operations, for the duration of this Agreement.
4.2.3 Provide and carry out actions necessary to ensure that quality services
are efficiently, effectively and responsibly delivered in the performance of
the purposes of this Agreement.
July 2002 Page 5 of 17
4.2.4 Work with property owners and development interests to ensure that the
ongoing structural integrity and flood protection performance of the Green
River Flood Control Zone District's levees and revetments will not be
compromised by local land use actions. This shall include, at a minimum,
maintaining existing easement areas and/or tracts of land established for
this purpose. Local land use actions shall also provide for the obtaining
of any additional easement areas or tracts of land reasonably necessary
to accommodate levee structural integrity and slope stability needs. Such
needs shall be determined in a manner consistent with applicable federal
levee engineering guidelines, and with any additional engineering or
geotechnical studies prepared for this purpose.
4.2.5 Coordinate flood hazard reduction planning and projects with the WRIA 9
Forum's plans and projects relating to conservation and restoration of
salmon and salmon habitat, and other projects of mutual benefit.
4.2.6 Coordinate flood emergency preparedness, response and post-disaster
recovery throughout the Green River Flood Control Zone District.
4.2.7 Work directly with the U.S. Army Corps of Engineers to coordinate dam
operations and other flood damage reduction programs and projects.
4.3 Green River Flood Control Zone District Administration. In accordance with
and as authorized by Chapter 86.15 RCW, King County shall administer the
Green River Flood Control Zone District and serve as the lead administrative and
technical agency for the Executive and Technical Committees under this
Agreement. Certain employees of King County will be assigned to work on the
implementation of the goals and objectives of this Agreement. King County
further agrees to:
Administration and Budget
4.3.1 Present for review by the Technical and Executive Committees the Green
River Flood Control Zone DistricYs annual work program and budget.
4.3.2 Use funds raised within the boundaries of the Green River Flood Control
Zone District in a manner consistent with the purposes of Chapter 86
RCW and the annual Resolutions authorized by the Board of Supervisors
that establish the annual budget and work program for the Green River
Flood Control Zone District.
July 2002 Page 6 of 17
4.3.3 Distribute an annual report to the Technical Committee by May 31 of each
year accounting for the revenue, expenditures and work accomplished by
the Green River Flood Control Zone District during the previous year.
Expenditures shall be categorized either as the costs for administration of
the Green River Flood Control Zone District or as the costs for
maintenance and repair of flood protections facilities and pump stations
within the Green River Flood Control Zone District. The annual report
shall include an accounting of the Green River Flood Control Zone
DistricYs designated and undesignated fund balances.
4.3.4 Pursue to the fullest extent practicable all federal, state and local funding
opportunities, grants and disaster assistance funding to maintain, repair
and/or retrofit the Green River Flood Control Zone DistricYs flood
protection facilities. This shall include, where feasible, the purchase of
rights and interests in lands and structures for the purposes of flood
control and/or flood hazard reduction and mitigation.
Maintenance and Repair
4.3.5 Maintain existing levees, revetments, access roads and other flood
hazard protection facilities and any appurtenances thereto, within public
easements granted for these purposes and/or within publicly owned tracts
of lands that lie within the Green River Flood Control Zone District. Such
actions and the repair of any damages caused by flooding at these
facilities are subject to budget availability and repair priorities.
4.3.6 Design and construct all levee and revetment retrofiUreconstruction repair
projects in a manner consistent with the guidelines and standards of the
"Guidelines for Bank Stabilization Projects in Riverine Environments of
King County (1993)," attached as Appendix B, as amended, revised or
updated from time to time by King County.
4.3.7 Design and construct all levee and revetment repair, retrofit, and
reconstruction projects in a manner consistent with slope stability findings
and structural design recommendations developed by Shannon and
Wilson, Inc., and set forth in their Summary Report: Slope Stability
Analysis of Four Green River Bank Stabilization Projects for King County
(January 1999), and any subsequent updates and revisions.
July 2002 Page 7 of 17
4.3.8 Design and construct all levee and revetment repair projects in
compliance with any requirements of the Endangered Species Act, and
other local, state and federal regulations.
4.3.9 Operate and maintain the Black River (P-1), Tukwila (P-17) and Segale
pump stations.
4.3.10 Perform project monitoring, as necessary, to evaluate facility performance
and to ensure that project design is in conformity with the requirements of
the Endangered Species Act and other conditions of federal, state and
local permits.
4.3.11 Complete annual levee inspection reports for the Tukwila and Horseshoe
Bend 205 projects for the U.S. Army Corps of Engineers.
4.3.12 Coordinate the Green River Flood Control Zone DistricYs projects and
activities with, and participate in, the WRIA 9 Forum's planning efforts for
salmon conservation. This will include continued support for and
participation in the U.S. Army Corps of Engineers' Green-Duwamish
Ecosystem Restoration Project, to the extent that such Project involves or
affects any of the Green River Flood Control Zone District's flood
protection facilities.
4.4 Pump Operations Procedures Plan. The Parties agree to abide by the 1986
Pump Operations Procedures Plan ("Plan"), as amended by the June 30, 1992
Green River Basin Program Interlocal Agreement, establishing specifications for
the operation of the Black River (P-1) and Tukwila (P-17) pump stations. The
Plan as amended is attached hereto as Appendix C. This Plan may be amended
by the Executive Committee upon unanimous approval of the representatives on
such Committee. The Parties further agree as follows:
4.4.1 Pump station operation and discharge shall be coordinated with gauged
flows in the Green River, up to the U.S. Army Corps of Engineers' Green
River Standard Project Flood flow profiles.
4.4.2 All new drainage systems discharging directly into the Green River
downstream of the Auburn gauge (USGS #12113000) must be designed
to cease operation when Green River flow reaches 12,000 cubic feet per
. second at the gauge, unless adequate mainstem levee and/or channel
capacity improvements are completed to accommodate the added
discharge, and provided that a minimum of two-foot of freeboard above
July 2002 Page 8 of 17
the Standard Project Flood elevation(s) over all affected mainstem levees
is maintained.
4.4.3 All pump stations are subject to shutdown in the event that the director of
King County's Department of Natural Resources and Parks, or the
director's designee, determines that there exists a substantial risk of
imminent levee failure or overtopping, or for public health and safety
emergency purposes.
4.4.4 All new drainage outfalls discharging directly into the Green River shall be
designed to cease discharging and to store up to the 100-year, seven-day
flood event when flows in the Green River equal 12,000 cubic feet per
second, as measured at the Auburn gauge, unless a party to this
agreement is granted an exemption subject to the guidelines established
in Sections V and VII of the 1986 Pump Operations Procedures Plan, as
amended.
4.5 Flood Warning and Emergency Response. For the purposes of coordinating
flood warning and emergency responses within the lower Green River basin, the
Parties agree as follows:
4.5.1 All Parties, subject to limitations of available staffing, technology, data
and funding shall provide accurate flood warning information within their
respective jurisdictions regarding the magnitude, timing and duration of
flood peaks in order to give floodplain residents, property owners,
business owners and others time to react to flood events by evacuating or
taking steps to protect property, improvements and possessions.
4.5.2 All Parties shall implement as necessary the Post-Flood Recovery Plan
for the Lower Green River Basin (1994) after flood events, and request
and coordinate federal and state flood disaster assistance.
4.5.3 King County shall staff flood patrols in the lower Green River basin
consistent with King County's flood warning procedures, and complete
river facility damage assessments as needed during and after flood
events and other major community disasters.
4.5.4 King County shall coordinate Howard Hanson Dam operations with the
U.S. Army Corps of Engineers to ensure that release rates during and
after flood events will minimize as much as possible flooding in the lower
Green River basin and damages to the Green River Flood Control Zone
July 2002 Page 9 of 17
DistricYs flood protection facilities. Information on dam operations during
flood events will be shared with the Parties.
4.5.5 King County shall, prior to each annual flood season, hold an annual
interagency flood preparedness meeting at a location in the Green River
Flood Control Zone District in order to review and update coordination
efforts with other agencies and businesses that participate in providing
flood warning and emergency response services.
4.6 Supplemental Work Program. Supplemental Work Program tasks, attached
hereto as Appendix D, will be incorporated into annual work program and budget
recommendations for the District and provided to the Executive Committee and
Board of Supervisors for review and approval.
5. TERMINATION. This Agreement may be terminated by any party, as to that party only,
upon sixty (60) days' written notice to the other Parties. The terminating party shall
remain fully responsible for meeting all of its obligations through the last day of the sixty
day notice period.
6. HOLD HARMLESS AND INDEMNIFICATION. To the extent permitted by law, and for
the limited purposes set forth in this Agreement, each Party shall protect, defend, hold
harmless and indemnify the other Parties, their officers, elected officials, agents and
employees, while acting within the scope of their employment as such, from and against
any and all claims (including demands, suits, penalties, liabilities, damages, costs,
expenses, or losses of any kind or nature whatsoever) arising out of or in any way
resulting from such Party's own negligent acts or omissions that may occur in relation to
such Party's participation and obligations under this Agreement. Each Party agrees that
its obligations under this subsection extend to any claim, demand and/or cause of action
brought by or on behalf of any of its employees or agents. For this purpose, each Party,
by mutual negotiation, hereby waives, with respect to the other Parties only, any
immunity that would otherwise be available against such claims under the industrial
insurance act provisions of Title 51 RCW. The provisions of this subsection shall survive
and continue to be applicable to Parties exercising the right of termination pursuant to
Section 5.
July 2002 Page 10 of 17
7. NO ASSUMPTION OF LIABILITY. Except as otherwise specifically provided for herein,
the Parties do not intend to assume any responsibility, risk or liability of any other Party
to this Agreement, or with regard to any other Party's duties, responsibilities or liabilities
under federal, state or local laws or regulations.
8. VOLUNTARY AGREEMENT. It is acknowledged and agreed by each Party that this
Agreement has been entered into on a voluntary basis and that no obligations other than
those provided for in this Agreement are being assumed by any Party as a result of
entering into this Agreement. This Agreement does not create, supplant, preempt or
supercede the existing authority or jurisdiction of any of the individual Parties.
9. NO PRECLUSION OF ACTIVITIES OR PROJECTS. Nothing contained in this
Agreement is intended or shall be construed to preclude any one or more of the Parties
from funding or implementing any work, activities or projects associated with any of the
purposes addressed by this Agreement through separate agreement or action, provided
that any such agreement or action shall not impose any funding, participation or other
obligation of any kind on any other Party, which is not also a party to such agreement or
action.
10. NO THIRD PARTY RIGHTS. Nothing contained in this Agreement is intended to, nor
shall it be construed to, create any rights in or any liability to any third party, including but
not limited to the members of the Executive Committee and Technical Committee in their
individual capacity, any agency or department of the United States government or the
State of Washington, or any other entity or person not a Party to this Agreement.
11. AMENDMENTS. This Agreement may be amended only by the unanimous written
consent of all of Parties. Any such amendment shall require approval by the governing
body of each of the Parties.
12. APPROVAL BY PARTIES' GOVERNING BODIES. This Agreement has been
approved for execution by appropriate action of each Party's governing body.
July 2002 Page 11 of 17
I WITNES W ERE F, the Parties hereto have executed this Agreement on the 12~-day
of zooz. CITY O UB Appr e s to
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By: B
64
Its: City Attorney
CI K~NT Approved as to form:
By: By:
Its: Ayo r A-,s-F"r` r City Attorney
.~1TY c7 . ENT.ON Appr as to form:
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p a; or, Jesse Tanner
City Attorney
ATTEST : fTK ~YL(,~
onnie I~altoity C-IerL-
CITY OF TUKW~ Ap oved as to f rm:
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BY~ ~ BY. ~ -
Its: Vq\ MuLLc-: t' City Attorney
KING C NTY ~Y Approved as to form:
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By: By:
Its: (^1;f King County Attorney
July 2002 Page 12 of 17
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APPENDIX B:
GUIDELINES FOR BANK STABILIZATION PROJECTS
IN RIVERINE ENVIRONMENTS OF KING COUNTY
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Bound separately from this agreement.
July 2002 Page 14 of 17
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- Guidelines for
~ Bank Stabilization Projects
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In the Riverine Environments of King County
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King County
Department of Public Works
Surface Water Management Division
~ Seattle, Washington
~ June 1993
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KING COUNTY EXECUTIVE
Tim Hill ~
KING COUNTY COUNCII
Audrey Gruger, District 1 1
Cynthia Sullivan, District 2 ,
Brian Derdowski, District 3
Larry Phillips, District 4 '
Bruce Laing, District 5
Ron Sims, District 6 ~
Paul Barden, District 7
Greg Nickels, District 8
Kent Pullen, District 9 ~
DEPARTMENT OF PUBLIC WORKS
Paul Tanaka, Director ~
SURFACE WATER MANAGEMENT DIVISION
Jim Kramer, Manager ~
Ken Guy, Assistant Manager
Dave Clark, Manager, River Management Section
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CONTRIBUTING STAFF
Jeanne M. Stypula, P.E., Project Manager
Alan W. Johnson, Technical Specialist ~Clint Loper, P.E., Senior Engineer
Sue Perkins, Earth Scientist ~
Ruoxi Zhang, Planning Graphics Supervisor
Laurel Preston, Graphics Technician
Ted Krause, Planning Support Technician ~
Wendy Gable, Graphics Technician
Ken Zweig, Planning Support Technician
. . ~
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Text will be made available in large print, braille, or audiotape as required.
Printed on recycled paper. ~
REFERENCED AS FOLLOWS: ~
THIS DOCUMENT SHOULD BE
Johnson, A.W. and J.M. Stypula. eds. 1993. Guidelines for Bank Stabilizaton Projects in the Riverine Environmeats of ~
King County. King County Department of Public Works, Surface Water Management Division, Seattte, Wash.
ii ~ .
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ACKNOWLEDGEMENTS
~ This document was Produced with the assis-
tance of many individuals who provided invalu-
' able knowledge and technical expertise. The
Surface Water Management Division wishes to
acknowledge Ms. Diane Ryba, Dr. Pat Trotter, Dr. ~
~ John F. Orsbom, P.E., and Ms. Andrea Lucas for
their contributions to this project in the fields of
' botany, fisheries, engineering and biostabilization.
The Division also wishes to acknowledge Dr.
Gary Minton, Ms. Robbin Sotir, Dr. Nelson
~ Nunnally, and Mr. Glenn Grette for their efforts in
the initial phase of this project under the direction
of Ms. Debra Hendrickson, former River Plan-
~ ning Program Manager and Mr. Tom Bean, P.E., .
Senior Engineer.
This project was partiallY funded from the
~ state Flood Control Assistance Account Program
(FCAAP), administered by the Washington State
Department of Ecology.
~ Many thanks to all reviewers who provided
insight, advice, and suggestions during the prepa-
~ ration of this document.
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CONTENTS
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PAGE
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PREFACE ............................xv ~
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CHAPTER 1 INTRODUCTION
~
1. 1 The Need For A New Approach 1-1
1.2 Scope and Intended Audience of the Guidelines ...................................................1-2
~ 1.3 Overview of the Guidelines 1-3
CHAPTER 2 THE RIVERINE ENVIRONMENT
~ 2.1 Stream Dynamics and Channel Erosion Processes 2'1
2.1.1 Floodplain Formation .................................................................................2-I .
` 2.1.2 Sediment Size and Bank Composition ......................................................:2-3
2.1.3 Channel Pattern and Channel Migration Processes 2-4
2.1.4 River Dynamics 2-5
2.2. Functions and Values of Riparian Systems ............................................................2-6
2.2.1 The Riparian Corridor ................................................................................2-6
2.2.2 Riparian Shade and Stream Temperatures .................................................2-8
~ 2.2.3 Impacts to Riparian Areas ..........................................................................2-8
2.3 Fish Communities in Pacific Northwest Streams ...................................................2-9
2.3.1 Salmonid Life Histories .............................................................................2-9
~ 2.3.2 Streambank Stabilization and Fish Habitat ................................................2-12
~ CHAPTER 3 MODES AND CAUSES OF BANK FAILURES
3.1 Streambank Zones 3-1
.
~ 3.2 Characteristics of Bed and Bank Material ..............................................................3-2
3.3 Streambank Failures ...............................................................................................3-2
3.4 Modes of Failure 3-3
~ 3.5 Causes of Failure ....................................................................................................3-3
,
3.6 Classification of Riprap Failures .........................................................:..................3-6
3.6.1 Particle Erosion ..........................................................................................3-6
~ 3.6.2 Translational Slide ......................................................................................3-8
3.6.3 Modified Slump ..........................................................................................3-9
~ 3.6.4 Slump
~ 3.6.5 Factors Contributing to Riprap Failures .....................................................3-10
~ v
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CONTENTS,, confinued
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PAGE
CHAPTER 4 PROJECT PLANNING
4.1 Preliminary Investigations .....................................................................................4-1 ~
4.1.1 Field Reconnaissance .................................................................................4-1
4.1.2 Problem Identification and Conceptual Solutions ......................................4-3 ~
4.1.3 Feasibility Analysis of Project Alternatives ...............................................4-3
4.2 Intermediate Project Stage .....................................................................................4-5
4.2.1 Data Collection and Analysis .....................................................................4-5
4.2.2 Pern-ut Applications ....................................................................................4-7 ~
4.3 Final Design ...........................................................................................................4-9
4.3.1 Plans and Specifications ................................:............................................4-9
' 4.3.2 Project Construction ...................................................................................4-9 ~
4.4 Post-Construction ..................................................................................................4-10
~
CHAPTER 5 PERMITS AND POLICIES
5.1 An Overview of Permits ......5-1
5.2 King County Regulations ......................................................................................55-3
-3
5.2.1 Sensitive Areas Ordinance ~
5.2.2 Shoreline Master Program ...................................................................:......5-3
5.3 King County Clearing/Grading Pernut 5-4
5.4 King County Shoreline Pernuts 5-5
5.4.1 Shoreline Substantial Development Permit ................................................5-5
5.4.2 Shoreline Conditional Use Pernut ..............................................................5-6
5.4.3 Shoreline Variance .....................................................................................5-6
5.4.4 Shoreline Exemption ..................................................................................5-7 ~
5.5 State Environmental Policy Act ............................................................................5-7
5.6 State Permits ..........................................................................................................5-8 ~
5.6.1 Hydraulic Project Approval ................:......................................................5-8
5.6.2 Coastal Zone Management Certification or Determination 5-9
~ 5.6.3 401 Water Quality Certification .................................................................5-9
~
5.6.4 Temporary Water Quality Modification Permit .........................................5-9
5.6.5 Aquatic Land Use Authorization 5-9
5.7 Federal Permits ................:.........................................................:..........................:5-10 ~
5.7.1 Section 404 Pernut 5-10
5.7.2 Section 10 Pernut ..................................................................................:....5-11
5.8 Conflicts In Regulatory Requirements ..................................................................5-11 ~
5.8.1 Contradictory Program Goals .....................................................................5-11
5.8.2 Design Criteria Related to Public Funding and Assistance Programs .......5-12
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CONTENTS, c«n,~nuea
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PAGE
~
CHAPTER 6 ROLE AND USE OF VEGETATION
~ 6.1 Effect of Vegetation on Bank Stability ..................................................................6-1
6.2 Limitations of Vegetative Measures ......................................................................6-2
~ 6.3 Plant Selection ........................................................................................................6-2
6.3.1 Checklists for Plant Selection ......................................................................6-2
6.3.2 Plant Communities ...........:..............................................:............................6-11
~ 6.3.3 Soils 6-14
6.3.4 Mulches ........................................................................................................6-17
6.4 Environmental Concerns in Plant Selection ...........................................................6-18
~ 6.5 Protecting Riparian Vegetation ..............................................................................6-19
~ CHAPTER 7 DESIGN GUIDELINES
~ 7.1 Streambank Zones ..................................................................................................7-1
7.1.1 Tce Zone ......................................................................................................7-2
~ 7.1.2 Bank and Overbank Zones 7-2
7.2 Design Options and Criteria for Different Methods ...............................................7-2
7.2.1 General Design Considerations ...................................................................7-2
~ 7.2.2 Rock Protection Methods ............................................................................7-4
7.2.3 Vegetative Methods .....................................................................................7-13
~ 7.2.4 Integrated Methods ......................................................................................7-18
7.2.5 Fish Habitat Components ............................................................................7-21
7.2.6 Summary of Design Considerations ............................................................7-27
7.3 Design Drawings, Plans and Specifications ...........................................................7-27
~ .
CHAPTER 8 CONSTRUCTION PROCEDURES
~
8.1 General Construction Planning 8-1
8.1.1 Construction Supervision 8-1
~ 8.1.2 Minimizing Site Disturbances During Construction ...................................8-2
8.1.3 Site Preparation 8-3
8.1.4 Labor Needs .................................................................................................8-3
~ 8.2 Construction Planning for Vegetative Methods .....................................................8-3
8.2.1 Acquisition of Plant Material .......................................................................8-3
8.2.2 Factors Affecting Plant Costs ......................................................................8-5
~ 8.2.3 Installation Timing for Vegetative Methods ................................................8-5
8.2.4 Handling, Delivery and Storage of Plant Materials 8-7
8.2.5 General Installation Procedures for Plant Materials ............:.......................8-8
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CONTENTS, co,tinuea
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8.3 Installation Procedures for Different Methods 8-9
8.3.1 Rock Protection ............................................................................................8-9 ~
8.3.2 Vegetative Methods .....................................................................................8-10
~ 8.3.3 Integrated Methods 8-19
8.3.4 Habitat Components .................................:...............8-25 ~
8.4 Construction Inspection and Site Cleanup 8-28 ~
CHAPTER 9 LONG-TERM SITE MANAGEMENT ~
9.1 Inspections and Monitoring 9-1
9.1.1 Rock Structures 9-1 ~
.9.1.2 Vegetative Systems ......................................................................................9-1
9.2 Maintenance ...........................................................................................................9-4 ~
GLOSSARY
~
REFERENCES CITED
~
APPENDIX A: A BRIEF DESCRIPTION OF MA10R RIVER SYSTEMS IN KING COUNTY ~
WITH NOTES ON FISH UTILIZATION AND SALMONID HABITAT
REQUIREMENTS
~
APPENDIX B: AGENCY AND TRIBAL CONTACTS
~
' APPENDIX C: METHODS FOR RIPRAP DESIGN
APPENDIX D: EXAMPLE CONTRACT SPECIFICATIONS ~
~
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viii
~
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LIST OF ILLUSTRATIONS
~
FICURE PAGE
......2-2
~ 2.1 Location map of the major river systems in King County .
~ 2.2 Valley cross-section showing relation of present channel to the floodplain and a
terrace (abandoned floodplain) 2-3
~ 2.3 Lateral migration. ............................................................................................................2-4
2.4 Neck cutoff . .....................................................................................................................2-5
~
2.5 Chute cutoff . 2-6
~ 2.6 Avulsion ..........................................................................................................................2-6
` 2.7 Typical life cycle of anadromous salmonids ...................................................................2-10
2.8 Rock outcrop-natural bankside feature showing positions typically occupied
by fish . .............................................................................................................................2--13
~
2.9 Uprooted tree-natural bankside feature showing positions typically occupied
by fish. .............................................................................................................................2-14
2.10 Natural in-channel boulders showing positions typically occupied
~ by fish .............................................................................................................................2-14
3.1 Section of streambank zones in natural channels . ...........................................................3-1
~ 3.2 Erosion and deposition caused by spiral secondary flow . ...............................................3-4
~ 3.3 Undercutting of a composite bank . .................................................................................3-5
3.4 Advanced stage of failure caused by particle erosion . ....................................................3-7
~
3.5 Failure caused by a translational slide 3-7
3.6 Failure caused by a modified slump . 3-9
3.7 Failure caused by a slump . ..............................................................................................3-10
~
4.1 Associated elements of bank stabilization projects . ........................................................4-2
~
4.2 Evaluation and selection of project solutions . .................................................................4-6
ix
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LIST OF ILLUSTRATIONS,.continued
~
FIGt1RE ~ PAGE
~
7.1 A bank stabilization project with a rock toe 7-1
.
7.2 Setback levee . ..................................................................................................................7-3 ,
7.3 A schematic of the minimum extent of protection required at a channel bend ...............7-4 ~
7.4 Downstream oriented rock deflector keyed into a streambank . ......................................7-6
7.5 Schematic diagram of a deflector . ...................................................................................7-7 ~
7.6 Turning rocks used to reduce erosion on the outside of a bend . .....................................7-11
~
7.7 Tie-back trench and revetment to prevent flanking .........................................................7-12
7.8 Live stakes 7-15 ~
7.9 Fascines 7-16
7.10 Brush mattress with a fascine . ....................................................:....................................7-17
7.11 Brush laYers. .7-18 ~
7.12 Joint planting . ..................................................................................................................7-19 ~
7.13 Vegetated geogrid . 7-20 ~
7.14 Live cribwall . ..................................................................................................................7-21
7.15 Tree revetment 7-22
7.16 Bank protection using large woody debris . .....................................................................7-24 ~
7.17 Boulder clusters . ..............................................................................................................7-25
7.18 Examples of symbols for plans and specifications. 7-30
8.1a Installation of rooted stock-single-stem tree . ...............................................................8-11 ~
8.1b Installation of rooted stock-shrub . ................................................................................8-11
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LIST OF ILLUSTRATIONS, confinuecl
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FIGURE PAGE
'
.......8-
8.1c Installation of rooted stock-mul6-stem tree 12
y .
~ 8.2 Installation of live stakes shown with an optional rock toe ke 8-14
8.3 Installation of fascine bundles. 8-16
~
8.4 Installation of a brush mattress with an optional fascine and rock toe . ....................8-17
~
.
8.5 Installation of brush layers . 8-18
~ 8.6 Installation of joint planting. 8-19
8.7 Installation of a vegetated geogrid shown with an optiona rock tce key . .................8-20
.
~ 8.8 Vegetated geogrid installadon using construction jigs and batter boards . ................8-22
~ 8.9 Installation of a live cribwall . ....................................................................................8-24
8.10 Installation of a tree revetment . .................................................................................8-26
~
8.11 Integrated system using large woody debris . ............................................................8-27
~ A.1 Washington State water resource inventory areas (WRIAs) of King County ...........A-2
C.1 Nomograph for determining DS0 based on velocity and flow depth C-6
~ .
C.2 Nomograph for deternuting the stone size based on velocities and side slopes C-7
~ .
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LIST OF TABLES
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TABLE PAGE ~
4.1 Field reconnaissance task list . ...................................................................................4-4
4.2 Technical analyses suggested -for bank stabilization projects . ..................................4-8 ~
5.1 A listing of permits and their general processing timelines for King County, ~
Washington State and federal agencies . ....................................................................5-2
6.1 A checklist for selecting the most appropriate vegetation for a bank
stabilization project . ..................................................................................................6-3
6.2 Characteristics of some native western Washington trees and shrubs with
high utility for bank stabilization projects .................................................................6-5
6.3 Wildlife use of selected species .................................................................................6-10
~
6.4 Species recommended for proposed plant associations for revegetation of
riparian corridors . ......................................................................................................6-12 ~
. 6.5 Moisture content, plant associations, erosion potential of King County soils, ~
and percent of mapped King county area covered by various soil types . .................6-16 .
6.6 Benefits and limitations of various types of mulches . ..............................................6-17
~
7.1 Grasses and ground covers recommended for use on and adjacent to channel
banks in western Washington 7-14 ~
7.2 Example maximum allowable design velocities for channels vegetated with
selected grasses . ........................................................................................................7-14
~
7.3 Recommended rock sizes for fishrocks . ....................................................................7-26
~
7.4 Summary of design considerations for various bank stabilization methods . ............7-28
8.1 Relative volume of plant cuttings required for various vegetative system ...............8-4 ~
8.2 List of local growers and nurseries providing native species in and nearby
King County . .............................................................................................................8-6 ~
9.1 Evaluation criteria for streambank vegetation ...........................................................9-2
~
9.2 Common problems of vegetation establishment, their diagnosis and remedies. ......9-3
xii ~
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LIST OF TABLES, continued
~
TABLE PAGE
~ C.1 Riprap sizes and conesponding weight. C-9
C,2 King CountY riPraP sPecifications by weight and least dimension . C-9
~
C.3 Washington State Department of Transportation riprap specifications
related to D30 and D50 diameters. ........................................C-10
~
C.4 Comparison of riprap gradations recommended by various agencies C-10
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PREFACE
~ These guidelines have been developed to as- Because integrated soil-plant-rock systems
sist scientists and engineers with the design of encompass many scientific areas, no single design
~ bank stabilization projects for river and streambank reference will cover all aspects of the project
protection in Westem Washington. This docu- elements in detail. Throughout the document,
ment include several types of inethods that use addirional reading sources have been referenced
~ various materials such as rock, timbers, soil, plants that should be utilized for design criteria. After
and natural fabrics. Together, these materials thoroughly reading this document, the reader will
create a complex matrix that join with the native have a basic understanding of the complexity of
~ bank materials to provide erosion protection. natural stream systems and utility of the bank
Bank stabilization projects that integrate veg- stabilization techniques.
~ etation with other materials have proved very This is a practical guide for assessing erosion
effectiveatstabilizingbankfailuresinKingCounty. problems, evaluating altemative soludons, and
Vegetadve methods also provide a number of designing and constructing a bank stabilization
~ important benefits such as enhancing fish and project. Careful pre-project planning, on-site
wildlife habitat, reducing local stream velocities, construction supervision and post-project mainte-
and lowering long-term maintenance costs. nance are all important elements of successful
r These guidelines are the first comprehensive stabilization projects. Integrating a well-planned
effort by King County in presenting information and constructed stabilization project with the
on bank erosion and stabilization techniques for unique characteristics of a river and stream will
~ large river systems. Presented within are many have long-lasting benefits.
types of bank stabilization methods. The docu- Readers are encouraged to share their suc-
ment, however, does not include all types of ero- cesses and failures with other practioners. In this
~ sion protection. Measures that require the use way, the successful application of these tech-
concrete, large amounts of wire or cable, or do not niques will be advanced in King County and
match the natural setting were not included be- throughout western Washington.
~ cause of their effects on the natural resources and
recreation values in western Washington streams.
~ This document was produced by several au-
thors who have extensive experience in a variety
of scientific fields. In doing so, the guidelines
~ reflect the multidisciplinary team needed to ana- _
lyze erosion problems and develop bank stabiliza-
tion solutions. An interdisciplinary team of soil
~ and plant scientists, engineers, geologists, and
fisheries biologists should be involved in every
phase of the project to ensure that important design
~ elements are included. Project proponents, espe-
cially those without technical expertise in river
systems, should always seek the advice of an
~ experienced, interdisciplinary team before decid-
ing on any course of action. These guidelines
should not be used in place of the interdisciplinary
team.
~ xv
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I CHAPTER 1 .
INTRODUCTION
~ .
Six major rivers and a large network of tnbu- Improvement Program). At present, that program
tary streams flow through King County. Most of is not funded to build any new capital improve-
~ these drainages originate in the upper elevations or ment projects. The program's bank stabilization
foothills of the Cascade Mountains in the eastern efforts are limited to maintaining projects built in
part of the County and flow westward to Lake previous years. However, even this basic level of
~ Washington, Lake Sammamish, and Puget Sound. service can be yuite expensive. For example, the
These rivers and streams are a highly valued cost of repairing damages to County-maintained
~ natural resource in the County, providing impor- revetments after the 1990 floods was estimated to
tant ecological, ecoriomic, recreational and aes- exceed $4.5 million.
thetic benefits to its residents. In recent years, numerous scientists and public
~ As the County's population has gown, an works managers responsible for river manage-
ever-increasing number of residents has chosen to ment have examined the traditional approach to
live, farm, or do business along its rivers and bank stabilization projects. These professionals
~ streams. Because most river and stream channels have debated if and when bank stabilization should
naturally move horizontally and vertically over occur and how stabilization projects should be
time, many developments along these waterways built and maintained. As a result of their efforts,
r may be threatened by erosion that causes new approaches are emerging.
streambank failures. Bank stabilization methods that use a combi-
Streambank failure is one of two major prob- nation of rock, soil and plant materials create a
~ lems associated with living nearthese waterways- complex grid, or matrix, of different materials in
the other is flooding. Both these problems cause the bank. As the vegetation in the project site
serious property damage in King County every becomes established, the bank becomes naturally
~ year and tend to occur coincidentally; that is the stronger and resistant to erosion, reducing the
high flows that cause flooding also tend to cause need for maintenance. At the same time, the
episodes of accelerated bank erosion. In 1990 vegetadon improves fish and wildlife habitat and
~ alone, flooding and bank erosion caused over $15 reduces local stream velocities. These projects
million to public and private property damage thus provide an environmentally sensitive, low-
~ along King County's rivers and streams (King maintenance solution with lower long-term costs.
County 1993). Bank stabilization techniques that use soil,
vegetation, and rock, have been successful in
~ various places across the United States and Eu-
1.1 THE NEED FOR A NEW rope. Most significant, however, is that a number
APPROACH . of recent projects have proven these methods to be
~ highly effective method of erosion control along
In the past, the solution chosen to protect major rivers and streams in King County. The
public and private properties from serious bank County has constructed these types of projects on
~ erosion typically was to cover the eroding bank the Cedar, Green, and Raging Rivers and Issaquah
with a blanket of riprap (i.e. large, angular rock). Creek. Two projects on the Raging River and
Riprap was dumped from the ends of trucks onto Issaquah Creek were installed only shortly before
~ the bank to create a re vetment. the record-setting November 1990 flows, leaving
Most of the riprap revetments built in King no time for vegetation to become established. The
County in the past were funded underthe County's projects, however, survived remarkably well.
` River Management Program (previously, the River Although minordamage was evident, these projects
~ Introduction 11
~
prevented further erosion of the immediate area tended to set regulatory thresholds. Rather, these
during unprecedented flooding. Today, these guidelines provide information and parameters ~
projects provide both effective erosion control and while leaving a fair amount of discretion to the
environmental enhancer►ent. engineer and other techtical specialists develop-
In recognidon of these new approaches to ing the project wtthin existing regulatory require- ~
bank stabilization, the 1993 King Counry Flood ments.
Hazard Reduction Plan recommended these tech- The application of bank stabilization methods ~
niques for numerous bank stabilization projects is evolving, and the body of empirical data is too
throughout the County. To fulfill this recommen- limited to provide the kind of precision found in
dation and satisfy an increasing demand for infor- traditional design manuals. Moreover, intuition as ~
mation about these methods, King County initi- much as practical science is needed when applying
ated efforts in 1990 to prepare bank stabilizadon these techniques. Professional and field experi-
guidelines. ence with problem-solving along rivers and ~
streams, and a thorough understanding of the
riverine site under investigation are all essential
1.2 SCOPE AND INTENDED for developing bank stabilization solutions. None ~
AUDIENCE OF THE GUIDELINES of these qualifications can be provided by any set
of written guidelines.
This document provides scientists, engineers For these reasons, these guidelines are in- ~
and other technical specialists guidelines for plan- tended for a very specific and well-qualified audi-
ning, designing, building, and maintaining bank ence. Users of this document should have a
stabilization projects along majorriversandstreams comprehensive background in river systems and ,
in King County. These guidelines are intended specific training in one or more of the following:
both for proposed bank stabilization projects along open channel hydraulics, sediment transport, geo-
rivers and streams and for the repair of existing morphology, riparian ecology, or aquatic and ter- ~
levees and revetments. The focus is on medium to restrial habitats. Because these guidelines rely
larger stream and river systems (systems with heavily on the designer's ability to integrate engi-
mean annual flows of 20 cubic feet per second or neering expertise with the soil, plant, and biologi- ~
more). These systems are regulated as "shorelines cal sciences, it is strongly recommended that a
of the state" under the King County Shoreline multidisciplinary team approach be used when ~
Master Program. The concepts included in this developing or reviewing possible bank stabiliza-
document, however, could be use in conjuncdon tion projects.
with other natural resource information when con- These guidelines are a first step in a long-term ~
. sidering revegetation projects on smaller sized effort to study, improve, and promote bank stabi- ~
streams. lization methods that enhance the natural resources
Fish habitat considerations are integral in bank of King County and western Washington. Refine- ~
stabilization projects and are discussed in that ment of procedures in this document is expected
context within this document. Detailed discussion and encouraged so that others may learn from the .
of fish habitat modifications not associated with creativity of innovative designers. ~
the specific goal of bank stabilization were consid-
ered beyond the scope of this document. Informa-
tion of channel modifications for the purpose of
benefitting fish habitat is available through many ~
other resources, and so, was not included in this
document.
These guidelines are not intended as a"design
manual" prescribing precise standards and formu-
las for bank stabilization projects. Nor is it in- ,
1_2 Introduction ~
~ 1.3 OVERVIEW OF THE GUIDELINES
The guidelines consist of nine chapters cover-
~ ing the following topics:
• Chapter 1 - this Introduction;
~ • Chapter 2- The Riverine Environment, a description of the geology and ecology of
~ rivers and streams in Westem Washington,
specifically King County;
~ • Chapter 3- Modes and Causes of Bank
Failures, a discussion of different erosion
and bank failure processes and how to
~ identify which process is at work; .
~ • Chapter 4- Project Planning, an overview
of what questions to ask, and what data to
gather, when planning a project;
~ • Chapter 5- Permits and Policies, a
discussion of government regulations,
~ permit requirements, and policy issues that
project planners need to understand;
~ • Chapter 6- Role and Use of Vegetation, a
description of how vegetation can be used
in bank stabilization, and the benefits it can
~ provide; • Chapter 7- Design Guidelines, a discussion
~ of various design options for different
circumstances, and guidelines for how to
select the best altemative;
~ • ChaPter 8- Construction Procedures, a
step-by-step description of how to install
~ bank stabilization projects;
• Chapter 9- Long-Term Site Management,
~ guidelines for how to monitor projects after
construction and maintain them to ensure
~ effectiveness.
These chapters are followed by a glossary of
~ important terms, a list of references for those seeking
additional information, and four appendices.
~ Introduction 1-3
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CHAPTER 2
I
THE RIVERINE ENVIRONMENT
~
Before beginning any bank stabilization ited by water. Because this material can again be
project, it is important for designers to understand transported by the river, both the bed and the banks
~ the physical and biological features of riverine of the river are moveable boundaries. The floors of
environments. While it is necessary to understand river valleys are composed of alluvium deposited
the individual aspects, it is equally important to by the river as it migrates back and forth' across its
~ understand how these features interact. This chap- floodplain. Floodplains are continually reworked
ter discusses the basic elements of river systems, as a river moves laterally, eroding one bank and
~ the functions and values of riparian areas, and depositing bedload material in a bar on the oppo-
describes fish communities in Pacific Northwest site bank. Under equilibrium conditions, erosion
rivers. of one bank is balanced by deposition on the-
~ The western slope of the Cascade Range has a opposite bank. Because of this balance, the width
diverse anay of rivers, including six major sys- and depth of the channel normally do not change
tems in King County: the South Fork Skykomish, appreciably over time.
~ Snoqualmie, Sammamish, Cedar, Green, and White As the river continues to move laterally away
(Figure 2.1). Within these river basins are hun- from a newly-formed bar, water-tolerant vegeta-
dreds of smaller streams that flow through for- tion such as willows, cottonwoods, and alders
` ested, rural, and urbanizing watersheds. As the begin to grow on the highest parts of the bar,
population of the area grows, the number of people furthest from the river channel. Deposits of large
who reside near rivers increases, placing a greater woody debris on gravel bars can facilitate the
~ number of citizens at risk from naturally occurring establishment of vegetation. During floods, this
river processes such as flooding and channel mi- brushy young vegetation resists erosion and re-
gration. Although dams on several of the larger duces water velocity enough to promote deposi-
~ rivers have reduced flooding, they have not elimi- tion of fine sediment suspended in overbank flows.
nated it. This greater population also increases the This process results in the formation of a two-part
number of human intrusions on watershed and bank, with coarser bed and bar sediment overlain
~ riverine areas. These intrusions often modify flow by fine overbank deposits. As each flood deposits
regimes and local channel characteristics. Through more sediment on the overbank area, the flood-
the permitting process and protection of sensitive plain will continue to grow vertically. As the
~ areas, various government agencies seek to mini- floodplain elevation increases, these areas are
mize the adverse effects of human activities on the inundated less frequently which allows woody
~ riverine areas. vegetation to become established. The original
willows and alders grow into a more diverse ripar-
ian forest that is eventually succeeded by a conif-
2.1 STREAM DYNAMICS AND erous forest. In time, when the river again reaches
CHANNEL EROSION this part of the floodpiain through laterai migra-
PROCESSES tion, these trees will be undercut by bank erosion
~ and fall into the river, supplying large woody
debris (LWD) to the river system.
2.1.1 FLOODPLAIN FORMATI4P) The height of the banks above the river bed is
1 governed by the size and frequency of flood flows
Most rivers in the inhabited areas of King which the river carries. Most natural rivers over-
County are entirely alluvial, i.e., their bed, banks, top their banks once every one to two years. Thus
~ and floodplain are composed of materials depos- the floodplain is an integral part of the river system
~ 1
The Riverine Ernironment. 2-
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C i:'i'if1..^'i;i4.:A•t.: ' tit: ~.ti{;yi\~iL:iCi'~~' :,ti~y:~hi't+{.,~• 'L'•;..<•~+~S:L`.~',.tl
O pli\4.\:~;•:::.; . :a:L..,
S~u
2•.. t.:.~:•?~;.. :;v:,:'•:::+:`:'\a;~'.;}:~,'~.'.,~t'}:*~.z;•~.~,5:<::.L.•h:. ":;,,,;y;~?'~1:
~ ti}}i4\:?t~:} : h }v}}.{j}, ``i}' ti}, ~
.r..,L+;vn;; . • :i• . '^.R~ •S~ ~ 1~`.h''+k~`'+...'",.,
:.;y vv':':' :`'$k.~iT~4't;i:\::i:.~ :..n+'~.`},n.;.,r~• \C2a;S, c 9 ' + ~
V o :.;t. :~'sfi~'•
~ ~ ~J;. a w `.;f;;:•;~;
.
\ta••;::,.Xkv.<:... . .
.a:,~•..,,,
N
~
2_2 The Riverine Ernironment ~
~ and water conveyance during floods. Due to sediment to the river channel. Bed material in the
~ changes in climate or other conditions, the valley upper Snoqualmie River, for example, is domi-
floor may contain remnants of abandoned flood- nated by gravel and cobbles. In the lower
plains (i.e., terraces) that, depending on their height, Snoqualmie River, the median bed material size
~ are infrequently or never flooded (Figure 2.2). declines to fine gravel and eventually sand, with
Unusually high terraces consisting of glacial sedi- coarser sediment occurring for short distances
~ ments line the edges of some King County river downstream of three major tributaries (Booth et
valleys such as that of the Raging River. al. 1991).
River banks composed of non-alluvial maten-
~ als, such as bedrock or glacial deposits, are com-
2.1.2 SEDIMENT SIZE AND BANK mon on smaller King County rivers with narrow
COMPOSITION floodplains (e.g., the Raging River). Non-alluvial
~ banks can also occur along large rivers where the
In general, resistance to bank erosion increases channel abuts a glacial terrace or valley wall.
with increasing grain size. Thus, abank composed While bedrock outcrops occur locally, the most
~ of cobbles is less erodible than a bank composed of frequently encountered non-alluvial materials in
sand. The presence of cohesive silt and clay also the Puget Lowland are glacial deposits. Although
increases resistance to bank erosion. bedrock erodes over geologic time, it can be con-
~ The size of sediment that a river transports is sidered non-erodible for design purposes. How-
determined by basin geology, water disc harge, ever, glacial de posits exhibit varying degrees of
and river bed (channel) gradient. As discussed erodibility depending on grain siu and density.
~ later, sediment size affects bank erodibility, chan- Deposits compacted by glacial ice (advance
nel pattern, and the predictability of channel outwash, till, advance glaciolacustrine deposits,
changes. In general, the smaller, steeper rivers in and all pre-Vashon deposits) are generally more
~ King County are gravel-bedded, while the largest, erosion resistant than alluvium.
longest rivers are sand-bedded, particularly in Glacial till, if not too fine-grained, can form
~ their lower sections. Sediment size generally de- nearly-vertical banks that erode very slowly. River
creases with distance downstream from a river's banks composed of sediment deposited at glacial
mountainous headwaters because as channel gra- margins or by the retreating glacier and therefore
dient decreases, the river can no longer transport not compacted by ice (e.g., recessional outwash,
~ coarser sediment. recessional glaciolacustrine deposits, and most
Sediment size can increase locally where steep ice-contact deposits) can erode very rapidly.
~ tributaries or valley wall erosion deliver coarse
~ Figure 2.2 Valley cross-seciion showing relatioe of present channe) io the floodplain and a terrace
(abandoned floodplain).
~
Abandoned itoodplain
or terrace
Hillslope
~ . .
Floodplain
I . . .
Channel
.
. . . .
.
. '.'Valle...flat
I~
~ -3
The Riv~erine Ernironment 2
In addition to simple bank retreat, deep-seated Convergence of flow causes erosion of the outer
landslides can occur in high banks of fine-grained bank near the downstream end of a bend, concur- t
glaciolacustrine deposits undercut by a river. Due rently with deposition of sediment in a point bar in
to the buildup of groundwater over reladvely im- the inside of the bend. If a bend already has a stable ~
permeable till or glaciolacustrine sediments, land- amplitude and wavelength, the entire bend moves
slides can also occur in overlying layers of coarse-
grained sediments. As a result, geotechnical ad- Figure 2.3 lateral migmtion. ~
vice should be sought for high non-alluvial banks
if there is any possibility of slope instability.
Outer bank ~
2.1.3 CHANNEL PATTERN AND
CHANNEL MIGRATION
Polnt bar 'ct• •
' PROCESSES Although alluvial river patterns (planforms) ~
are often classified as straight, meandering, Ot Wa: Deshed lines denote channel posltJon aRer mlg►ation takea p/ace.
braided, there actually is a continuum of forms.
Sinuosity, defined as channel length divided by laterally downstream while essentially maintain- ~
valley length, is an index of the degree of ineander- ing its shape (Figure 2.3).
ing of single-thread rivers. Rivers with a sinuosity The same bend may last for years without ~
above 1.5 are referred to as meandering; rivers less major changes in planform. In a well-developed
than 1.5 are referred to as sinuous. Sinuosity meander bend undergomg lateral rrugration, the
correlates well with the type of sediment transport locus and direction of future bank erosion are ~
and hence channel slope and grain size. Meander- somewhat predictable over the short-term. If the
ing is best-developed in rivers whose banks con- bend is located in a river reach with a lower than
tain sufficient silt and clay to be cohesive and to characteristic sinuosity, it is likely that the bend ~
limit the rate of erosion. High sinuosity also occurs will grow outward as well as downstream.
in reaches of coarse-sediment rivers where mean- The size and tighmess of ineander bends are
der bends impinge on valley walls. Low sinuosity limited by cutoffs in which the river abandons a ~
(less than 1.3) and shallow, wide channels are bend and takes a straighter, steeper path. As a
typical of bedload-transporting rivers with weak, meander bend develops (radius of curvature de-
non-cohesive gravel or sand banks (Schumm 1977). creases), the water slope decreases upstream of the ~
Straight channels (sinuosity of 1.0) are rare in bend. This promotes deposition in the channel and
alluvial rivers and often often short-lived, since diversion of flow and a consequent cutoff. Neck
meanders will tend to develop naturally. Straight cutoffs (Figure 2.4) occur only on very tight bends, ~
channels are more common in steep, nanow moun- and hence are generally found on low-gradient '
tain valleys. rivers with fine-grained banks. Good examples of
Bank erosion occurs when the boundary shear tight bends and the oxbow lakes left behind by ~
stress (a measure of the force per unit area exerted neck cutoffs are found along the Snoqualmie River.
by the water on the bank or bed) exceeds the shear Formation of new channels by chute cutoffs
strength (the intemal resistance of the soil to and avulsions (Figures 2.5 and 2.6) is common in ~
movement) of the channel boundary. Shear stress, gravel-bed rivers with a large sediment load, par-
which increases with increased water surface slope ticularly in reaches where decreasing gradient or
and depth, tends to be greatest along the outside of widening of the valley causes sediment deposi- ~
river bends. tion. Under these conditions, sediment deposition
Lateral migration of ineander bends is the can rapidly fill the existing channel and promote ~
dominant erosion process in meandering rivers. the rapid switching of flow (avulsion) into a backbar
2„4 The Riverine Ernironment ~
~
Figure 2.4 Neck a*tf. have occurred or are anticipated, design of bank
~ protection should be undertaken cauCiously, real-
izing that the life of the project may be limited by
changed conditions.
2.1.4 RIVER DYNAMICS
~
A river adjusts its bed, banks, channel location
- and pattern to transport the water and sediment
~ discharge it receives from upstream. By deposit-
ing or eroding sediment from its bed and banks, it
Note: Dashed lines denote channe/ position alter migretion takes place. CaII adjuSt 1tS W1dtll, depth, S10pe, size of bed
~ material armor and channel pattern. Since mul-
channel (Figure 2.5) or into an entirely new chan- tiple adj ustments can occur in response to a change
~ nel across the floodplain (Figure 2.6). Large woody in water and sediment load, it is not always pos-
debris jams that block a significant portion of the sible to predict the nature of a river's response.
channel can also cause avulsions. The develop- Nevertheless, generalized relationships have been
~ ment and growth of ineander bends in gravel- developed which relate changes in sediment or
bedded rivers is severely limited by chute cutoffs water discharge to possible changes in channel
and avulsions, which tend to destroy bends before morphology (e.g., Schumm 1977; Heede 1986).
~ they can become large. Consequently, gravel- Given enough time, these changes in channel
bedded rivers tend to be straighter than rivers with morphology enable the river eventually to adjust
cohesive, fine-grained bed materials.' In extreme to the new water and sediment regime, at which
' cases, multiple chute cutoffs and avulsions can point it will stabilize.
produce a braided channel pattern. An increased load of sediment (in particular,
Cutoffs and avulsions can occur abrupdy and coarse sediment transported by the river as bedload)
t often catastrophically. After a cutoff or avulsion into a reach will result in deposition if the river
takes place, flow progressiveiy diminishes in the cannot transport sediment through the reach as fast
abandoned channel as its entrance becomes plugged as it is supplied. Depositional zones generally
~ with sediment. Because the steep slope of the new occur where channel slope decreases abrupdy,
channel enables rapid erosion, the new channel where a river widens downstream, in backwater
may widen and deepen rapidly as it progressively areas upstream from channel constrictions, or
cazries more of the flow. Erosion on such develop- where a steep tributary enters a larger river. By
ing channels can be both rapid and unpredictable. depositing sediment and raising its bed (aggrada-
Deposition of the eroded material from the devel- tion), the river locally increases its slope and the
oping channel will occur where the gradient de- energy with which it can tiansport sediment through
creases downstream of the cutoff or avulsion. the reach. Another common response to an in-
This, together with the changed angle of attack of crease in sediment load is widening of the river
~ the river, promotes bank erosion downstream. channel. Deposition of sediment will also tend to
Although the timing and precise location of cut- promote cutoffs and avulsions, which straighten
~ offs and avulsions cannot be predicted, inspection the channel and increase its slope. Channels in
of bend and floodplain morphology and historic which deposition has occurred can often be recog-
aerial photographs should occur as part of most nized by their high width-to-depth ratios and the
~ bank stabilization projects. This analysis can yield presenee of voluminous sediment deposits.
valuable insights into the frequency of such events If sediment load decreases, the opposite re-
and possible paths which the river might take in sponses will occur. The channel may narrow (as
` the future. In reaches where cutoffs and avulsions vegetation grows on formerly active bars), deepen,
The Riverine Emironment 2-5
~
~
or become more sinuous. If braided, it may revert upstream and downstream may also adjust. In
to a single-thread pattern. Channels which are addidon, the cause or nature of the changes to ~
becoming narrower and deeper can often be recog- which the river is responding may not be idendfi-
nized by their lower width-to-depth rado, unusu- able. Often, simple field observations will enable
ally high banlcs, and small or absent bars. the designer to determine whether the river reach ~
An increase in discharge (the size and number of interest is aggrading, degrading, or relaNvely
of floods) increases the energy available for ero- stable.
sion, causing the channel to enlarge to accomma ~
date the increased flows. Enlargement may in-
volve both widening and deepening and an in- 2.2 FUNCTIONS AND VALUES
OF RIPARIAN SYSTEMS ~
Figure 2.5 Chuie cuioff.
When evaluadng various project designs, it is ~
important to consider not only the physical setting
and effects of the project, but also its biological
k ~t;;w.. context. Projects installed without considering the ~
~
~ surrounding biological communities can have
-
-
~ negative effects on fish and wildlife resources.
"
,,,o,,: Q,sh.d ,;,e, dwxft a,m,,,, pos~ ,e,a„ ~r~,,,, ~takes aece. many King County rivers makes bio ogical con- ~
, siderations particularly important issue in bank
stabilizadon design. ~
Figure 2.6 Awlsion.
2.2.1 THE RIPARIAN CORRIDOR S
The riparian corridor is an ecologically dis-
. ~
Vegotgod ~ tinct area bordering rivers and streams. The width
~ n°°dplain
of this zone varies with the toPagraPhY, climate
, ,
and other factors. It is an area where soils are often
saturated and periodically inundated. Because of ~
,,,,a: oas,,ed M.s oowt.,~nel po,om en.,,ygmkv Mt.9 aac.. the proximity of surface and ground water, which
produces unique water and soil conditions, veg- ~
etation in riparian areas is usually very different
crease in bend wavelength. If the increase in from that of upland areas. This is especially true m
discharge is not accompanied by an increase in larger, low-gradient rivers such as the Snoqualmie ~
sediment load, the slope of the river bed will River, where cutoff oxbows, backwaters, and high
decrease. In some cases, this will result in a coarser water tables create unique biological communities
streambed until the river's sediment transport ca- not found in smaller, steeper streams.
pacity again matches its sediment load. Slope may To understand the effects of various project ~
decrease due to erosion of the bed (degradation) or design options, it is important to understand the
due to increases in bend wavelength or sinuosity. influence of riparian systems on. streams. The ~
A decrease in discharge will tend to promote the various functions of riparian systems have been
opposite responses. reviewed by many authors (Karr and Schlosser
As the above examples imply, river channel 1977; Meehan et al. 1977; Budd et al. 1987; ~
responses to changes in sediment or water dis- Raedeke 1988; Bilby 1988; Murphy and Meehan
charge are complex. A change in one reach of river 1991; Gregory et a1.1991; Beschta 1991; Castelle
can result in slope adjustments to which reaches et al: 1991). ~
2-6 The Riverine Ernironment
. ~
~ .
Bilby (1988), in discussing the major interac- the ground, and thus affects understory composi-
' tions between aquatic and terrestrial ecosystems, tion.
says that upland and aquatic systems are intri- In the Pacific Northwest, riparian vegetation
cately interconnected physically, chemically, and can directly and significantly influence the physi-
~ biologically. Thus, because they affect one an- cal conditions of the stream environment. The
other, impacts to either can impact the other. roots of riparian vegetation stabilize streambanks,
Upland areas influence riparian areas by af- retard erosion, and create overhanging cover for
~ fecting the shape of stream channels, by control- fish. The above-ground portions of plants dissi-
ling the type, rate, and amount of material passing pate the energy of stormflows, obstruct the move-
through the system, and by providing a primary ment of sediment and detritus, and provide large
r source of food and other nutrient inputs to the organic debris to streams (Meehan et al. 1977;
stream channel. Changes in these factors often Bottom et a1.1985; Hunter 1991; Sedell and Beschta
lead to changes in the species composition and age 1991). Sedell and Beschta provide many insights
~ structure of plant, fish and wildlife populations. on the interaction and influence of streamside
Some commonly recognized functions of ri- vegetadon on stream hydraulics.
parian zones include (adapted from Castelle et al. Erman et al. (1977), Roby et al. (1977), Meehan
~ 1991): et al. (1977) and Murphy and Meehan (1991)
discuss the importance of overhead canopy shade
~ • stabilizing streambanks and resisting ero- and input of organic matter from the riparian zone
sion; to the aquatic and terrestrial invertebrate commu-
• filtering suspended solids, nutrients, and nities. Meehan et al. state that the food base for the
~ harmful or toxic substances; benthic invertebrate communities of forest streams
• moderating the microclimate of the ri- consists of leaves, needles, cones, twigs, wood,
parian system; and and bazk. The insect cor_imunities that live on this
~ • supporting and protecting fish and wild- plant material are a significant food source for
life species. trout and juvenile salmon. In fact, the most wide-
spread and important foodstuff of running-water
, Other important funcrions are not commonly fishes is invertebrates (Hynes 1970; Meehan et al.
recognized. These include moderating impacts of 1977; and Reiser and Bjomn 1979). During sum-
stormwater runoff, protecting and buffering stream mer periods, 40 to 50 percent or more of the dief of
~ habitats from adverse impacts, and maintaining stream- dwelling trout and juvenile salmon con-
and enhancing habitat diversity and integrity, and sists of terrestrial insects (Hynes 1970). These
providing migration corridors for fish and wild- insects usually enter streams by falling off riparian
~ life. Riparian zones are also sources of large woody vegetation (Reiser and Bjornn 1979). When ter-
debris which is an important habitat component in restrial insects become scarce during winter peri-
aquatic ecosystems. ods, trout feed almost exclusively on aquatic in-
i The composition of riparian plant communi- sects.
ties is defined by the interaction of several envi- Many species of Pacific Northwest wildlife
ronmental factors including available soil mois- are either dependent on or find optimum habitat in
~ ture, light, and length of growing season. Each of riparian systems. Phinney et al. (1989) state that of
these factors results from interactions of other the approximately 480 species of terrestrial and ~ variables. For example, soil moisture is dependent shoreline wildlife in Washington, 291 (609'0) are
on precipitation, depth to water table, drainage and regularly found in wooded riparian habitats. The
permeability. Precipitation and growing season, reasons for this include the proximity of habitat
1 which are affected by climate and elevation, also requirements (i.e., food, cover, and water), the
influence species composition. Composition and increased number of niches because of wider di-
density of the overstory determines light levels on versity of plant species and structure, and the high
, edge length-to-area ratio that result from the linear
The Riyerine Ernironment 2'7
~
v ~
shape of most riparian zones. Edge areas are the tures rise or fall is influenced mostly by stream
border or interface between open and wooded size. Small streams heat and cool quickly, while ~
areas. larger streams will respond more slowly. Between
sampling points in very small streams, changes in
riparian shading can change water temperatures in ~
2.2.2 RIPARIAN SHADE AND minutes. Temperature changes in larger rivers
STREAM TEMPERATURES require hours to days (Caldwell et al. 1991).
For smaller streams with relatively nazrow ~
Water temperature regulates the biological widths (1-15 feet), a combination of understory
functions, distribution and behavior of strearn fish and larger vegetation is very effective in providing
and invertebrates. High water temperatures in riparian shade. For medium-width streams (15-30 ~
streams can change the distribudon of juvenile feet), larger vegetation, even when set back from
fish, cause thermal stress or death of juvenile and the water's edge, can effectively shade the stream. ~
adult fish, or delay the upstream migration of adult Taller vegetation will only partially shade larger
fish returning to spawn (Bjornn and Reiser 1991). streams and rivers (i.e. wider than 50 feet); com-
The range of water temperatures in a given plete shade coverage on lazge rivers is generally ~
stream, in particular the maximum temperature, is not possible. Even partial riparian shade, however,
a function of heat gains and losses (Beschta et al. will contribute to cooler air and water tempera-
1987). Water temperatures are influenced by re- tures. ~
gional climate conditions, such as air temperature
and relative humidity, and by channel characteris-
tics such as stream width, depth and shade level. 2.2.3 IMPACTS TO RIPARIAN AREAS ~
As air temperatures increase or streams become
larger, water temperatures tend to increase. Since The effects of land uses on riparian areas can
air temperatures are warmer at lower elevations, be muldple and varied, depending on the type of
the warmest water is generally found in low eleva- land use, degree of disturbance to streamside veg-
tion, large rivers. Conversely, the coldest water is etation, size of stream, physical setting, and suc-
generally found in high elevadon mountain stneams. cession after disturbance. While land use may ~
Riparian shade and groundwater inflow rates vary, the resulting environmental alterations gen-
are other important factors in determining stream erally affect riparian systems in similar ways.
temperatures. As the amount of riparian shade Increases in sediment to streams from the loss of ~
increases or the proportion of groundwater to total riparian vegetation, forexample, will occurwhether
flow increases, stream temperatures tend to de- the loss of vegetation results from road construc- ~
crease. A heavily shaded stream in summer, for tion, logging or livestock grazing.
example, will generally be two to five degrees The effects of altering streamside vegetation,
Centigrade cooler than nearby unshaded streams particulazly overhead canopy, have been the sub-
of the same size. Because of the smaller total ject of considerable research and many reviews
flows, smaller streams are influenced more by (Brett 1956, Brown 1969, Patton 1973, Beschta et
, cool groundwater temperatures than larger streams al. 1987). Significant alteration to or removal of ~
(Beschta et al. 1987; Sullivan et al. 1990). overhead canopy allows increased direct sunlight
Riparian shade also influences the water tem- to reach the stream. This is especially true when
peratures of large, wide rivers but to a lesser extent the canopy extends all the way across the stream, ~
than small streams. Shade from riparian vegeta- limitingthe amount of lightthatreaches the ground.
tion can cool shallow nearshore areas. These shal- Direct sunlight, especially in summer, can in-
low, nearshore areas are often critical rearing areas crease water temperatures and in turn affect fish ~
for juvenile fish. and ayuatic insect species composition and growth.
As a stream flows between shaded and un- High summer water temperatures can kill salmon
shaded reaches, the rate at which water tempera- and trout, increase the incidence of many fish '
2_8 The Riverine Ernironment ~
~ y
diseases, provide a habitat that favors less desir- 2.3 FISH COMMUNITIES IN
~ able fish, inhibit spawning activity, block spawn- PACIFIC NORTHWEST
ing runs into streams, affect the quantity of food STREAMS
available, and alter the feeding activity and body ~ metabolism of fish (Lantz 1971). The fish habitat components of most stream
Hicks et al. (1991) report that several studies projects in the Pacific northwest are intended to
have shown the importance of streamside man- meet the needs of one or more salmon or trout
~ agement as a tool to protect fishery values. These species. Generally, salmonids are typically the
studies compared fish habitat and salmonid popu- species of interest because of their aesthetic, rec-
lations in streams that were and were not given reational and commercial value.
t riparian protection during timber harvests. The While the focus is generally on salmonids, it is
evidence shows that maintaining riparian zones-- important to note that healthy stream systems
zones in which specific measures are taken to harbor fish assemblages encompassing many more
~ protect water quality and fish and wildlife habitat- species. More than 50 non-salmonid fish species
-can reduce damage to habitat and helps maintain inhabit the streams of western Washington. When
, the integrity of fish populations. This evidence is designing stream modification projects the habitat
generally consistent over a wide span of time and requirements of natural fish assemblage's, not just
space. single target species, should be met. Because the
~ Soil compaction can be caused by many events, distribution and habitat requirements of salmonid
including passage of heavy equipment, livestock, and non-salmonid species overlap, it is generally
humans, and even rainfall. Because of the variabil- assumed that meeting the habitat requirements of
ity of site conditions, impacts from the same event salmonids will meet the requirements of non-
may vary from negligible to severe on different salmonids. For each proposed project, this as-
sites. Extensive soil compaction can result in re- sumption should be verified. Wydoski and Whitney
~ duced growth of vegetation, increased runoff, and (1979) provide an excellect overview of
heavier storm flows (Adams and Frcehlich 1984). Washington's fishes and their life-history and
Compacted soils reduce the vigor of vegetation in habitat requirements.
~ several ways. The greater density of the soil pro-
vides more resistance to the expanding root sys-
tem; air, water, and nutrients also move more 2.3.1 SALMONID LIFE HISTORIES
~ slowly through soils with minimal pore space.
Water can collect on the surface of slow-draining The Pacific salmon life cycle is often dis-
compacted soils, further reducing air movement to played as a generic pattern common to all species
~ the root zone (Adams and Froehlich 1984). Al- (Figure 2.7). While each species generally has the
though compacted soils can be a good site for seed same life history stages, there are variations in life
germination, development is frequently stunted. history, not only between species, but also among
~ The presence of stunted vegetation may indicate stocks within species. These variations are re-
severe soil compaction. In addition, the events that flected in habitat use. The between-species varia-
caused compaction (e.g., grade changes, road or tions represent the individual niches occupied by
~ home construction) may also have damaged roots each species. The between-stock variations repre-
of trees and shrubs, stressing the plant and poten- sent the myriad of adaptations to local habitats and
~ tially introducing disease organisms to the dam- conditions.
aged areas (Davidson and Byther 1982.) Pacific salmonids depend on stream habitat in
different ways and for different lengths of time at
1 each life history stage. These life history-specific
habitat requirements are modified by important
species-specific and stock-specific requirements
'
The Riverine Ernironment 2'9
~
~
and by local conditions. Local adaptations appear • time at which they spawn;
in such traits as: • survival after spawning; ~
• time of entry to the stream; • length of juvenile freshwater rearing;
• distance adults travel upstream on their • habitat types required for juvenile
spawning migration; freshwater rearing; ~
• types of watersheds and gradients • level of social interaction among juve-
preferred; niles; ~
• ability to navigate obstacles; • length of time spent in saltwater; and
• type and location of spawning habitat; • distance traveled offshore.
. ~
Figure 2.7 Typical life rycle of anadromous salmomds. (Adapied from Adams and Whyte 1990.)
~
EGGS
~~n~ ,
'~:,y~~.•r~k' ¢}~y;~ .
\;~;yti.. ;}~'~v~`~;
l\'~?~yy'~* ~ " ~Yi•' c:• y"4
. :i44~•~ti:~.+:{ n}ti~. . •'~Q..{ k'+2.s±}.. ~'•~h;
~+~.'Q~~£$ Y~ `V+~ •
r 'y„`•~}sN\\y\ 'ki, i 4' . . ~ .
~ . . ~
eam 9ravel
. Eggs in str
hatch in 1-3 months.
. ~4::. ' : L:••.
~ k
SPAWNING • ~t•~ ` ALEVINS
;~~~~:{`;~',~;;i„o,o„ Fish spawning in Alevins in stream
' . '
• • freshwater stream.
gravel 1-5 months. ~
ti, ~''c,. .
v Upstream migration to Fry emerge from gravel
spawning stream. in spring or summer.
tl
:i; ~
Timing of migration to Juvenile fish in freshwater a ~
spawning grounds depends few days to 4 years depending
on species and race. on special and locality.
Smott migration to ocean usually FRY
in spring or early summer. Fish
NATAL STREAM ~1k spend 1 to 4 years in ocean.
~ ~;.,~:s~"
i4'•~?ti' ~'~~.'~~v~: ~;w Freshwater
l•h~+.;\:;•,~h..
J}`i k' y~.*`•Y:}\+\
~~\.';~~L4y,~.~`i~'',~.• .k~.ti},~ :'{,t. ~ rearing species.~
t'v}; . .
k 1.; ..11+~ ~ti•
` l"~,<`~~ Non-freshwater
. . . ~ ~ rearing species.
7 ~
ADULTS ~
2_ 10 The Riverine Environment ,
~ M
This document focuses on streams with mean year or more in freshwater depending on the stock
~ annual flows of 20 cfs and greater. Salmonids use (Groot and Margolis 1991).
such streams and the habitats they provide in every Sockeye salmon (O. nerka): Sockeye salmon
stage of their freshwater lifecycle. Virtually all of spawn in the fall as three-, four-, five- and some-
~ King County's river systems historically provided times six-year olds. They choose rivers and small
habitat suitable for the spawning, rearing, and streams flowing into lakes, lake outlets, and some-
migration needs of many anadromous and resident times lakeshores for.spawning. Some populations
' fishes. The following is a general summary of the are known to spawn in streams without associated
life history characteristics of the salmonids found lakes. Adults spawn only once and then die. Juve-
~ in King County. Further information on the fish niles spend one to three years rearing in freshwa-
life history and their use of the major river systems ter; most (but, as noted, not all) populations rear in
of King County is discussed in Appendix A. De- lakes. There is also a resident form (kokanee) that
~ tailed information and specific requirements can matures at a smaller size after rearing and feeding
be obtained from the references listed at the end of in lakes (Groot and Margolis 1991).
this chapter. Coho salmon (O. kisutch): Most coho spawn
, Pitik salmon (Oncorhynchusgorbuscha): Pink in the fall or early winter as three-year old fish and
salmon have a two-year life span from egg depo- occasionally as four-, or sometimes five-year old sition until death. Puget Sound stocks of pink fish, or in some stocks as two-year old "jacks."
~ salmon, which spawn in odd numbered years, Adults can travel far upstream into a variety of
migrate only short distances upstream to spawn. habitats, passing fornudable barriers to reach small
Adults spawn once and then die. Fry emerge from tributaries for spawning. Adults spawn only once
~ the gravel in late February through March and and then die. Fry emerge from the gravel in spring.
immediately migrate to saltwater (Groot and Juveniles rear in streams one to two years prima-
Margolis 1991). rily in pool habitats (Gioot and Margolis 1991).
i Chum salmon (O. keta): Chum salmon spawn Steelhead (O. mykiss): Depending on the
as three-, four-, or five-year olds in the fall or early stock, adults retum to freshwater after one, two, or
winter. Wtiile adults generally travel a bit further three years in saltwater. They can travel long
~ upstream than pink salmon, they may be stymied distances, and seem to prefer large or moderate-
by obstacles other salmonids navigate with ease. size watersheds with high gradient throughout.
Adults spawn once and then die. Fry emerge from While most steelhead return to freshwater in win-
~ the gravel in March or April, and migrate to ter, some drainages have spring, summer, or fall-
saltwater quickly after emergence (Groot and run fish. These fish return at an earlier stage of
~ Margolis 1991). maturity and wait in freshwater until spawning.
Chinook salmon (O. tschawytscha): Chi- Spawning occurs in late winter to spring in
nook salmon are the largest of the Pacific salmon. mainstem reaches or in swifter tributaries. While
~ Generally considered to be fall spawners, some some adults survive spawning, multiple spawning
stocks spawn as late as January. Although adults is not common. Juveniles rear one to three years in
return from saltwater as three-, four- or five-yeaz freshwater pool and riffle habitats (Meehan and
~ olds, some stocks have high proportions of small Bjornn 1991).
but sexually mature two-year old "jacks." De- Resident rainbow trout (O. mykiss): Both
pending on the distance to be traveled and time of freshwater migratory and stream resident life his-
~ spawning, upstream migrations may occur in any- tories occur. In stream resident forms, maturity
time of the year. Spring and fall stocks are most may be reached at age two orthree, and, depending
common in Puget Sound. Mainstem reaches are on the size and productivity of the stream, at a very
~ generally chosen for spawning. Adults spawn once small size. Maximum age may be only four or five
and then die. Fry emerge from the gravel in spring, years. These fish show a preference for riffles and
mostly at night. Juveniles may spend weeks to a habitats with swifter flows. -
~
, The Riverine Ernironment 2 > >
~
Searun coastal cutthroat trout (O. clarki dence that these species may they may migrate
clarki): Adult cutthroat trout retum to freshwater higher in the watershed than any other Pacific ~
in the late summer, fall, or winter of the year they salmonid for spawning, and overcome baniers
fitst go to sea, and typically do not overwinter in impassible to other large fish (C. Kraemer, WDW, ~
saltwater. They favor small or moderate-size wa- per. comm. 1991). These fish return from saltwa-
tersheds with extensive low-gradient areas in their ter in late summer or fall and spawn in the fall;
lower reaches. Adults typically spawn for the Fust adults survive spawning very well. Fry emerge ~
time at age three (males) and age four (females), at from the gravel in the spring with j uveniles rearing
a length of about 12-14 inches. Some fish return- 3, 4 or more years in freshwater (WDW 1992).
ing to freshwater for the first time overwinter ~
without spawning. Spawning occurs in late winter
to early spring in small tributaries., preferably in 2.3.2 STREAMBANK STABILIZATION
reaches above those utilized by coho. Adults sur- AND FISH HABITAT ~
vive spawning very well, and repeat spawning is
common. Fry emerge in the spring to reside two, Rivers are active systems that naturally change
three, or more years in freshwater. Juvenile cut- their configuration from year to year. One of the ,
throat trout defend temitories in streams, but are principal processes that brings this change about is
usually dominated by both coho and steelhead streambank erosion. Erosion is a natural process
juveniles (Trotter 1989). that can be either positive or detrimental, depend- ~
Resident coastal cutthroat trout (a clarki ing on the type of materials being eroded, the rate
clarki): Both freshwater migratory and stream at which erosion occurs, and socioeconomic con-
resident life histories occur. The age structure of cerns. ~
these populations is similar to searun cutthroat Streambanks composed of gravels and coarse
trout, except non-migratory populations mature materials are good sources of spawning and rear-
about one year earlier (age two or three) and are ing substrates. Gravel streambanks subject to ero- '
shorter-lived and generally smaller than searun sion, often the targets of bank stabilization projects,
fish. When cutthroat and rainbow trout exist in the can be the primary sources of new spawning ,
same stream, the cutthroat trout occupy the upper substrate within the stream. Conversely,
reaches and the rainbow trout the reaches further streambanks made up mostly of sand, silts, and
downstream. Cutthroat trout prefer quieter water other non-cohesive materials can be sources of ~
than rainbow trout and are often found in pool fine sediment and debris that may adversely affect
habitats (Trotter 1989). Spawning occurs in the fish habitat. Streams with excessive amounts of
spring. fine sediment may be incapable of transporting it ~
Dolly Varden (S. malma) and bull trout (S. through reaches of larger gravels used by salmo-
confluentus): Although considered to be different nids for spawning. When this fine material is
species, Dolly Varden and bull trout are similar in deposited, it fills the voids between the larger ~
appearance and behavior and in the Pacific North- gravels. This decreases the flow of water to incu-
west, their ranges overlap. Both species exhibit bating embryos and smothers aquatic invertebrates
andromous and freshwater migratory and non- that provide food for juvenile and adult fish. ~
migratory life histories. Lirce searun cutthroat trout, The rate at which erosion occurs is a major
anadromous fish return to freshwater the same factor in deternuning whether it is beneficial or
year they go to sea; these fish do not typicaily detrimental. A gradual process of natural erosion ~
overwinter in saltwater. While they attain maturity promotes habitat diversity by creating features
at age five or six, and may spawn agam every year such as pools with undercut banks, rootwads ex-
or every other year thereafter, maximum age may posed in the bank, eddies, backwaters, sloughs and ~
be 12 years or more. Dolly Varden and bull trout oxbows. These features provide stable habitat for
seem to prefer lazger watersheds or stream sys- multiple ' species and stages of the salmonid
tems with a lake for overwintering. There is evi- lifecycle. In contrast, if erosion is rapid or abrupt, i
2-12 The Riverine Ernironrnent ~
~ • µ
land is simply lost without creating any of these the desirable features will benefit fish and help
` important habitat features. maintain the productivity of the stream. Structures
Stream margins are the principal habitats of that channelize the river or change the basic chan-
newly emerged salmonids during the fust few nel configuration (e.g., increase stream gradient,
~ crucial weeks after emergence. Smolts also make increase water velocity, reduce streamside cover,
use of stream margins for shelter during their or decrease overall habitat diversity) do neither.
passive migration to saltwater. Loss of these habi- Riprapping or rock cribbing can be beneficial
, tats through any activity that removes cover or to fish if the banks are left with irregular surfaces
reduces the roughness of the stream margin can to create turbulence and pockets. Riprapping
adversely affect salmonid productivity. For spe- projects tliat severely alter a natural stream chan-
' cies such as fall chinook salmon and steelhead that nel, however, will have a detrimental effect.
often spawn in mainstem reaches and larger tribu- Knudsen and Dilley (1987) found that the severity
taries, alteration of spawning habitats by inadvert- of the alteration depended on how much of the
~ ent changes in the stream channel or velocity streambed was graded and leveled by equipment
profile can also be detrimental. working in the stream, the amount of streamside.
Figures 2.8 and 2.9 illustrate bankside features cover that was replaced by riprap, and the degree
' and Figure 2.10 shows large in-channel boulders to which machinery operated within the streambed
where fish may find energy-efficient positions. to place riprap.
' Streambank stabilization structures that emulate
, F;gure 2.8 Rock outcrop-naturol bankside feature showing postions typically occuPied by fish.
~ L•'• • ' \
~ : ' vs^,, ~:;.1:~ . • . . . . • . . •
.~S{ i• 't; . . . .
. . 4• :i:~. y, . . . .
~ tti • • . ' .
~ •4` ~ • :.••Y.'•~•.f• . •yL~.
~ • f,• ~ .
♦
i F,oW
~
~
1
.o . . ~ . . . .
~ . . o. :
' • ' PLAN VIEW
.
, .
Tiie R'rverine Erwironment 2-13
'
Figur+e 2.9 Uproofied tnee-nalurol bankside feature showing positions iypically occupied by fish.
~
. . :o,. . . . o.. : . . . . . . . . . ~
~
Fl~' ~
.
. . : :o . ~ . . . . , . :
/
, PLAN VIEW
Figure 2.10 Naturol in-channel boulders showin9 Posifions f YPicallY oauP'ed bY fish. ~
~
~
. . , :o, . . . v.. . . . : . , . : . : . ~
~
~
Flow
✓J i~
~
~
. . . . . . . : : : , : . . . . . . . : : . . . .
, • . . , • . PLAN VIEW ~
2-14 The Riverine Ernironment ~
RECOMMENDED SOURCES FOR
~ ADDITIONAL INFORMATION
s and rivers. In Stolz, Trotter, P.C. 1989. Coastal cutthroat trout: A
~
Bisson, P. A. 1991. Stream _
J. and J. Schnell, eds. Trout. Harrisburg, Life History Compendium. Transactions
' PA, Stackpole Books (The Wildlife of American Fisheries Society 118: 463-
Series). pp. 135-143. 473.
~ Bjornn, T. C. and D. W. Reiser. 1991. Habitat wydoski, R. S. and R. R. Whitney. 1979. Inland
Requirements of Salmonids in Streams. Fishes of Washington. University of
American Fisheries Society Special Waslungton Press. Seattle, Wash.
~ Publication 19:83-138.
~ Everest, F. H. and 7 co-authors. 1985.
Salmonids. In_ E. R. Brown, editor.
Management of Wildlife and Fish Habitats
~ in Forests of Western Oregon and
Washington. U. S. Forest Service and
Bureau of Land Management. Portland,
' Ore. pp. 199-230. Groot, C. and L. Margolis, eds. 1991. Pacific
` Salmon Life Histories. University of
British Columbia Press. Vancouver, B.C.
~ Meehan, W. R. and T. C. Bjornn. 1991.
Salmonid Distributions and Life Histories.
American Fisheries Society Special
~ Publication 19:47-82.
Reiser, D. W. and T. C. Bjornn. 1979. Habitat
~ Requirements of Anadromous Salmonids.
In W. R. Meehan, editor. Influence of
~ forest and rangeland management on
anadromous fish habitat in the western
United States and Canada. USDA Forest
~ Service, General Technical Report PNW
96.
~ Rosenbauer, T. 1988. Reading Trout Streams.
Lyons & Bu=ford Publishers. New York,
N.Y.
'
Schumm, S.A., 1977. The Fluvial System. John
Wiley & Sons, New York, N.Y.
,
~ The Riverine Ernironment 2-1 5
' . °
' CHAPTER 3
MODES AND CAUSES OF BANK FAILURES
' 'on of sireambank zones in naturol
To effectively control bank erosion, river bank Figure 3.1 Sech
channels.
' management must be compatible with the nature
of the river system and the composition of its
banks. Before restorative methods are applied to
~ eroding banks, it is essential to unde*stand the ~y
mechanism of erosion. Otherwise, large invest- "
ments of time and money may potentially be
' wasted in projects that fail or require frequent maintenance. This chapter discusses various forms
and causes of bank failure.
~ A.0
~ • ~
3.1 STREAMBANK ZONES
Streambanks can be divided into three general zones: toe, bank, and overbank zones. Although the boundanes between these zones are imprecise
,
because river levels vary seasonally, they are
~
useful in subsequent discussions. These zones are :
, i;}ivYi+ it•'.\' k`<'::.'.. . I
shown in Figure 3.1, and can be described as
roe ~ ea~k ; Overbank
follows (adapted from Logan 1979): Z~1e , Z~1e , Z~,
Toe Zone. The toe zone is that portion of the
~ bank between the ordinary high water (OHW) and
low water levels. This is the zone most susceptible
to erosion as it is exposed to strong currents, debris during occasional periods of high water (i.e., gneater
~ movements, and wet-dry cycles. This zone is nor- than bankfull flows). This zone is generally sub-
mally inundated throughout much of the year. In jected to periodic dry periods in which the soil
areas where stabilization is necessary, non-veg- moisture is primarily dependent on characteristic
~ etative structural protection is normally required rainfall of the area. When relatively flat and
in this zone because few woody plants can tolerate generally underlain by alluvial deposits, this area
~ year-round inundation. is also called a floodplain. When it rises steeply
Bank Zone. The bank zone is that portion of and directly from the streambank, this area is
the bank above the OHW mark (OHWM) that is called a bluff.
~ inundated during periods of moderate flows (i.e., In some situations, tce protection with riprap
up to bankfull flow). Although above OHWM, or other structural means may be the only
these sites are still exposed to periodic erosive streambank protection required. Usually, struc-
~ currents, debris movement, and traffic by animals tural protection below OHWM will be combined
and humans. The water table in this zone is with vegetarive designs above OHWM. Com-
frequently close to the soil surface because of its bined
failnre and yeld greaterlbcnefits
, proximity to the river. ecton aga
Overbank Areas. The overbank area is that for aquatic and terrestrial ecosystems. The design
portion of the bank from the bank zone inland that of bank protection measures is discussed in Chap-
~ is subjected to inundation or erosive action only ter 7.
' 3-1
~ ~Aocles cnd Causes of Bank Failures
3.2 CHARACTERISTICS OF BED saturated, these banks are more likely to fail due to
AND BANK MATERIAL mass wasting processes such as sliding. ~
Stratified or Interbedded Banks. Stratified
The resistance of natural river banks to erosion banks are the most common bank type in natural ~
is closely related to the characteristics of the bank fluvial systems. The soils in stratified banks con-
material. While these materials are highly vari- sist of layers of materials of various sizes, perme-
able, they can be broadly classified as follows ability, and cohesion. When cohesionless layers ~
(Henderson and Shields 1984; Simons, Li and are interbedded with cohesive soils, erosion po-
Associates 1982): tential is decided by the erodibility of the compo-
Bedrock. Bedrock outcrops normally are quite nent layers and the thickness and position of the ~
stable and subject only to quite gradual erosion cohesionless strata. Where cohesionless soil is not
and intermittent mass failure. Bedrock outcrops in at the toe of the bank, the layers of cohesionless
a bank or bed can prompt erosion of the opposite soil are protected by adjacent layers of cohesive ~
bank. soils (the cohesionless soils are still subject to
Cohesionless Banks. Streambanks composed surface erosion). This type of bank is vulnerable to
of cohesionless soils normally are highly stratified erosion and sliding because of subsurface flows ~
heterogeneous deposits. Cohesionless soils con- and piping. Where the cohesionless soil occurs at
sist of mixtures of silts, sands, and gravels. These the toe of the bank, it will generally control the
soils have no electrical or chemical bonding be- retreat rate of an overlaying cohesive unit (Thorne ~
tween particles and are eroded grain by grain. and Lewin 1979).
Erosion of cohesionless soils is controlled by ~
gravitational forces and particle characteristics
such as size, gram shape, gradarion, moisture 3.3 STREAMBANK FAILURES
content, and relative density. Other factors in- ~
clude the direction and magnitude of flow veloci- All stream banks erode to some degree. Be-
ties next to the bank, fluctuations m water turbu- cause is a natural ongoing process, it is unrealistic
lence, the magnitude and fluctuations in the shear to believe that bank erosion can be or should be ~
stress exerted on the banks, seepage force, and totally eliminated. Major floods can always make
piping and wave forces. significant changes in bank lines despite steps
Cohesive Banks. Erosion of cohesive taken to prevent it. Thus, it is important to under- ~
streambanks is more complex to analyze than stand that the concern is not that erosion occurs,
cohesionless banks because of the characteristics but rather the location and rate at which it occurs.
of soil particle bonding. Cohesive soils contain While bank erosion is occurring naturally over ~
large quantities of fine clay particles composed of time, it is a process that may be accelerated or
- chemically active minerals that create strong chemi- decelerated by human activities. Henderson and
cal and electrochemical bonds between particles. Shields (1984) define natural erosion as the pro- ~
Other soil characteristics affecting cohesive soil cesses that occur without significant human ac-
erosion are the type and amount of cations in pore tivities in the drainage basin or catastrophic natu-
water and the eroding fluid, and composition of ral events such as volcanic eruptions or forest ~
the soil including the type and amount of clay fires. They define accelerated erosion as erosion
minerals. Cohesive material is generally more that is atypically high in magnitude and is different
resistant to surface erosion because its low perme- in nature than the erosion experienced at the site or ~
ability reduces the effects of seepage, piping, frost reach in question in the recent past. Both natural
heaving, and subsurface flow on the stability of the events (e.g., high flows) and human activities
banks. Because of the low permeability, this ma- (e.g., changes in land use) can cause accelerated ,
terial is more susceptible to failure during rapid erosion. In western Washington, for example,
lowering of water levels. When undercut and/or major changes in water quantity, flow direction, or ~
debris loads often accelerate bank erosion. These
3_2 Modes and Causes of Bank Failures ,
types of changes are often caused by human activi- Geocechnical failures chac are unrelaced co hydcau-
' ties such as urbanization, logging or overgrazing. lic erosion are nearly always caused by excess bank
moisture problems. Moisture can affect both the
These activities usually result in increased runoff S~sses and the ability of the bank material to
and sediment yield compared with a basin in a w,ithstand stresses. Failure usually results when the
~ natural condition. shear strength of the bank material is exceeded.
Bank stabilization projects should not degrade Mass wasting of soil at the tce of the bank is one
indication that a geotechnical failure has occurned.
the river environment or create a need for contin- ,j,he appearance of che failed bank can vary wich the
' ued, costly maintenance. To prevent this, it is material type and the precise cause of the failure.
essential to understand both the channel responses B~ failures from a combination of hydraulic and
to changes in flows and debris loads, and the geotechnical forces are more common than either
' processes of river bank erosion. Simons, Li and force alone. Literally,hundreds of scenarios can be
Associates (1982) provide a thorough discussion developed under which a combination of these
~ of the variables affecting river channels and the forces result in bank failures. Examples include:
forces causing failure and erosion of river banks. bed degradation that leads to oversteeping the
banks and subsequent geotechnical failure; or, when
successive slip plane failures occur on a
' 3.4 MODES OF FAI LU RE geO~chn'cally °nscable bank and hyaraulic forces
erode mass wasted material at the tce that is resist-
ing further slips.
~ Bank failures in riverine systems occurthrough
one of three modes (Fischenich 1989): 1) hydrau- Other large scale features that can affect river
lic forces that remove erodible bed or bank mate- systems, such as landslides, debris torrents, or
' rial; 2) geotechnical instabilities; or 3) a combina- mass failures will not be discussed in this docu-
tion of hydraulic and geotechnical factors. ment.
Fischenich explains each as follows:
~ When bed or bank erosion occurs because water 3.5 CAUSES OF FAILURE
flowing in the channel exerts a stress that exceeds
' the critical shear stress for soil erosion, the mode of The actual causes of bank erosion related to
failure is hydraulic. Critical shear stress is depen- hydrauliC and geotechniCal modes of fa'tlure are
dent upon the rype and size of the material. It can be
exceeded by tangential shear stress caused by the complex and varied. They involve streamflow
~ drag of water or by direct impingement of water characteristics, streambank properties including
against a bank. Bed degradation is an example of groundwater conditions, and the effect of human
che firsc, while local scour induced by debris is an aCtivities. Successful bank stabilization projects
~ example of the second. Hydraulic failure is usually begin by identifying the cause of failure.
characterized by a lack-of vegetation, high bound- Fischenich (1989) describes the causes of ero-
ary velocities, and no mass soil wasting at the tce of
the Sion as follows:
~ bank.
The hydraulic mode of bank failure generally Erosion from hydraulic forces is generally restricted
to circumstances that either affect the velocity or
~ occurs on rivers with noncohesive gravelly banks, direction of flow. Frequendy, human acaons are
such as the Tolt River in King County (Shannon responsible. Examples of actions that can increase
and Wilson 1993a). Rivers with fine-grained bank mean [and local] velocities include increased flows
~ sediments, such as the lower Green River, gener- w;ch land use changes, sceeper channel slope from
ally experience the geotechnical mode of failure channelization, or constriction of the channel for
discussedbelow(Fischenich1989).AgeoteChniCal bridge crossings. Changes in flow direction are
usually the result of debris in the channel, forma-
, failure occurs when gravitational forces acting on tion of new islands or bars, or the improper place-
the bank material exceed the strength of the resist- ment of flow defleccion structures. Desm~ccion of
ing forces, causing downward displacment of the bank vegetadon from land clearing, logeing, live-
' soil mass.
Modes ond Causes of 8ank failwes 3-3
~
r
stock grazing, or ocher riparian use can aiso pro- layers consisting of an upper layer of cohesive silt
mote erosion by hydraulic forces." material (commonly reinforce by plant roots) un- ~
derlain with noncohesive gravels. As water flows
An example of bank failure caused by hydrau- along the bend, secondary currents remove the
lic action is toe erosion. Tce erosion typically noncohesive material at the tce creating a cantile- ,
occurs when flow is directed toward a 6ank at a ver overhang of cohesive material (b). At the toe of
bend (Figure 3.2). In channel bends, the highest the bank, where shear stress exceeds critical shear ~
velocity is close to the outer edge of the channel stress, particles are detached from the bank by the
and near the center of water depth. Forces act on flowing water. This oversteepens the bank, caus-
the bank in both the downstream and the vertical ing noncohesive particles higher up on the bank to
direction toward the base of the bank. Centrifugal fall off in thin, vertical slices. When the cohesive ~
force causes the water surface elevation to be silt layer is undercut, the cantilever overhang
highest at the outside of the bend (superelevation). collapses into the eroded pocket (c). This loose, ~
As gravity pulls the additional mass of water fallen material is then washed downstream, result-
downward, a rolling, helical spiral is created, with ing in a repositioned bank line or bank retreat
high downward velocities against the bank mate- (Thorne and Lewin 1979). ~
rial. This downward erosive force, coupled with Toe erosion or streambed degradation may
the stream velocity, can undercut the toe of the also lead to geotechnical bank failures by increas-
bank. The downward erosive force on the bank ing the height of the bank to the point where the ~
will be greatest in tight bends as opposed to gradual sliding forces exceed the resisting forces (shear
curves. The most severe toe erosion will occur strength) of the bank materials. Bank failures from
immediately downstream from the point of maxi- only geotechnical forces are normally related to ~
mum curvature. At these locations, an increased moisture conditions within the bank. As previ-
level of protection will be required. Levees and ously mentioned, moisture can affect both the
revetments can become undercut, resulting in stresses within the bank and the bank material's ~
slumps, modified slumps and translational slides. ability to withstand those forces. Geotechnical
These are discussed in detail in Section 3.6. failures commonly occur after the flood peak has
The process of undercutting is presented in a passed, when banks are saturated and have been ,
sequence of illustrations in Figure 3.3a, b, c, and d. oversteepened by undercutting. Common examples
In the initial position (a), the bank has composite of situations that may lead to this type of failure are
as follows (USACOE 1981 and Richards 1982): ~
Figure 3.2 Erosion and deposi6on caused by • Failures induced by rapid drawdown occur ~
spirol secondary flow. (Adapted from when the river stage falls following a flood,
Kunzig 1989.) leaving the banks saturated. The pore water
pressure in the bank reduces frictional shear ~
SL"reievaw strength of the soil and increases sliding
warer w"8°° forces by adding weight to the soil mass.
This type of failure tends to occur in fine- ~
grained soils that do not drain rapidly.
/
, t,~. , • Banks are destabilized by the piping of soil ,
>,;x ; • £ ;,~.~;~~::>~.r• .
;yv .s•..;~>: s~..
~ ~ ~ 4}! • `.':'••h+.l'~~ P
: articles from lenses (thin laYers) of
}J•`~~ ~\,~:;:...•:c~f~~;``~.`.~.`~;'`•.., ; ec;~,~
cohesionless sands. The piping undermines
. .t}•: . .'4i\?''':w: •
O° , , ~~~,~'y}+••• , ~'ti•}:' .
Erosion L: the overlying bank materials which then ,
, .,.e~
. } #•~,~,.`...~..i' ~
mne ; • . ~~~i~• zone
collapse.
. o:'~~:t:>.,,. . v }'{.'y ♦ t k .
o • . • ~
3-4 Modes and Causes oF Bank Failures ,
M
Figure 3.3 Underartling of a composihe bank. (Adapfed from Thorne and Lewin 1974.) y
'
'
Cohesive silt layer
o . G
o ~ o a) Initial bank position.
Non-cohesive gravel °
° . . o
' o • ' • eo e . e • o ~ o o C)
0 0
' Cantilever
overhang
rAL..~n~l ~ 4x: i . • ~ ~ ,r .
r•Y.+Y .
:,sr;?}~;;.,.w~,~:• ' . . r
~ + o .ls o
Secondary current
e o o. e ° e
(spiral) b) Toe erosion.
< a ~
Initial bank position
, o ° . .
' e ° o , o e a o
o ~ o o~ o° o
~ " ~~;~~:•~~w;~ R,,, - Fallen material from
c.~ . • ~,~o . .;r
cantilever overhang
c) Failure of cantilever overhang.
Initial bank position
o - ~
• ° o
. p • o 0
° o e ° o° ~ , ` ° ~ ° • ° ° o ° p ° o
, . .
' k'` : ~}6 :~si,.+:: . ~ : '
o ' 'r Fallen material •
• 6' o o o ' removed by erosion d) Repositioned bank line.
a
Initial bank position
O `J o C'
~
Mades and Causes oF 8ank Foilures 3-5
'
r
• Expansion and contraction of soils during the mound is its tendency to confine high velocity
weddry or freeze/thaw cycles cause tension flows between the mound and the toe of the em- '
cracks that lead to bank failure by collapsing bankment, causing additional bank and bed ero-
or toppling of blocks of soil. sion.
The probable causes of particle erosion are: '
• Subsurface moisture changes weaken the
internal shear strength of the soil mass at the • The median size stone (D50) was not large '
interface of different soil types. enough to resist the shear stress of the
stream.
• Capillary action temporarily decreases the
angle of repose of the bank material to less • Abrasion or removal by impact of individual ,
than the existing bank slope. The stones. For this and the previous situation,
oversteepened slope subsequently fails individual stones are lost, and in time, the ,
when the soil dries and capillary forces are cumulative effect results in riprap failure.
no longer present.
• The side slope of the bank is so steep that the ~
displacing forces read.ily exceed the resisting
3.6 CLASSIFICATION OF RIPRAP forces of the riprap, causing instability of
FAILURES the individual stones. ~
As vital as it is to understand the failure of • The gradation of riprap may be too uniform
natural river and stream banks, it is also important (all stones near the median size). Without ~
to understand the failure of riprapped structures sufficient smaller diameter stones to fill the
such as rock revetments and levees. This informa- voids and provide lateral support for larger
tion is particularly necessary in the design of material, failure may occur even if the ,
repairs in that the inherent problem must be under- median size is adequate and the bank side
stood before it can be effectively corrected. slope is not too steep. ,
Blodgett and McConaughy (1986) identify
fourbasictypes ofriprap failure alongstreambanlcs:
1) particle erosion, 2) translational slide, 3) modi- 3.6.2 TRANSLATIONAL SLIDE ~
fied slump, and 4) slump. The cause and correction
of each type of failure is different. Blodgett and A translational slide is caused by the downslope
McConaughy describe each failure as follows: movement of a mass of stones, usually along a ~
horizontal fault line (Figure 3.5). The riprap is
undisturbed except at the fault line and a bulge at
3.6.1 PARTICLE EROSION the toe. If the moving mass is not gready de- ,
formed, it may be called a block slide. The initial
Particle erosion is the transport of riprap to the phases of a translational slide are indicated by
channel bed near the installation or to a point crack parallel to the channel in the upper part of the ~
downstream. Particle erosion is considered the riprap bank. The movement of translational slides
most common type of failure. Figure 3.4 shows an is controlled by: 1) variations in shear strength
advanced stage of failure caused by particle ero- along the interface between the riprap and the base ,
sion. Displaced riprap usuaily comes to rest on the material, and 2) stability of the riprap at the junc-
bed near the eroded areas and at some distance tion point with the channel bed. A translational
downstream. A mound of displaced riprap on the slide is initiated when the support of the upslope ,
channel bed suggests that the transport capability material is reduced by channel bed scour and
of the stream is insufficient to move all of the undermining of the toe of the riprap, or by particle
eroded riprap from the site. A detrimental effect of erosion of the toe material. In either case, the shear ~
3-6 Modes and Causes oF Bank Failures ,
r
Figure 3A Advanced siage of failure caused by pariide erosion. (Adapted from Blodgelt and McConau9hy
' . 1986.) .
' Rock riprap
' Scarp ~ ~e ir
r' . ~i-
~
. ~ i. ~
Rocks too large
' for transport r
~^~r ^ ~ • Q \ ~~t
' DisFlaced rock and ~ \i~-f~`\ ` " ~ • • : . ' ;1
base material ; ~
' • , Base
material
' , . . . .
Channei bed
Figure 3.5 Failure caused by translational slide. (Adopled from Blod9ett and McC°e°ughy 1986.)
, .
Rock riprap
~
' Scarp r , ~ ~ c r
r. ~
r
. ~
~
~ Fault line
- . ~ • • `~N\~
/ ~ i• ' ;
,
r
( r` r ii
I
Rock riprap ~ • ~ ~
Base
material
, . . . ' ' ' , ' , . ' . Failure plane
• • • . .Channel'bed' , . at interface
~
Modes and Causes of.Bank Failures 3-7
'
,
resistance of the interface between the bed mate- from the various slumps discussed by Schuster
rial and riprap may be insufficient to resist trans- and Krizek in that the failure plane is located in the ,
lational movement. riprap, and the underlying material supporting the
The translational slide may progress downslope riprap dces not fail (Figure 3.6). As a result, the
indefinitely if erosion of riprap at the toe contin- surface of the rupture is not concave, but is a ~
ues. Continued downslope creep of the riprap may relatively flat plane.
also occur if the base material underlying the While this failure is similar in many respects to
riprap is saturated with water and the shear resis- a translational slide, the geometry of the damaged ~
tance along the interface is less than the sliding riprap is also similar in shape to the initial stages
force. of failure caused by particle erosion. The new side
A translational slide with the fault line located slope within the modified slump area is flatter than
~
high on the embankment suggests that extensive the slope of the interface between the base material
channel bed scour or particle erosion undermined and the riprap. Material that is dislodged from the ~
the toe of the embankment material. In this situa- failure is similar to what occurs in a typical slump
tion, the slide would occur only when the mass of failure on hilly terrain. The displaced stones may
riprap was sufficiently lazge for the downslope cause increased turbulence of flow and eddy ac- ~
forces to exceed the shear strength at the interface. tion along the bank in the area of the slump. The
Translational slides also occur when excess hy- secondary current may then cause addidonal riprap
drostatic (pore) pressure in the base material causes failure by particle erosion of smaller materials, ~
reduced frictional resistance in riprap at the inter- especially those exposed at the scarp. An interest-
face between the two layers. Excess pore pressure ing factor about modified slump failures is that
may develop during periods of high precipitation, while the median stone size (Do may be adequate ~
floodmg, or rapid fluctuation of water levels. A for the site, movement of certain key stones (pos-
filter blanket on the base material probably would sibly due to poor gradation) leads to a localized ,
not prevent this type of failure and may provide a failure of the riprap. r
potential failure plane. The probable causes of modified slump fail-
The probable causes of translational slide fail- ures are:
ure are: , a
• The bank side slope is so steep that the
• The bank side slope is too steep. riprap is resting very near the angle of
repose. Any imbalance or movement of ~
• The loss of foundation support at the tce of individual stones creates a situation of
the riprap because of channel bed scour or instability for other stones in the riprap.
degradation, or by particle erosion of the ~
lower part of the riprap. • Certain stones, critical in supporting upslape
riprap, are dislodged by settlement of the ,
• Excess hydrostatic (pore) pressure reduces submerged riprap, impact, abrasion, or
the frictional resistance along the interface particleerosion. Theloss ofsupportprovided
between the riprap and base material. by the key stones results in the downslope '
movement within a local area near the point
of the dislodged stones. This cause of failure
3.6.3 MODIFIED SLUMP may be reduced in frequency if the riprap ,
material is of proper size gradation.
Riprap failure that occurs as a mass movement
along an internal slip surface is called a modified ,
slump. Slumps are described by Schuster and Krizek (1978) as rotational slides along a concave
surface of rupture. A modified slump is different ~
3-8 Modes and Causes oF Bank Fcilures ,
r .
Figure 3.6 Failure caused by modified slump. (Adapted from Blodgetf and McConaughy 1986.)
'
~ Scarp
t Failure plane ~r
within riprap r r,.
' ~ r^
Displaced r ~ rock riprap
.
'
r
, ~ .
Rock riprap r ~ , . .
`
. r r/`
r~ r ~ \
~ • . . . : . . , .
' • ` : Base
. ,
material
, Channel bed - , • '
• , ,
' .:C ^w • ' . • • .
~
' 3.6.4 SLUMP gressive slump failures along the face of the riprap,
the areas of instability may enlarge until the entire
A slump is a rotational-gravitational move- bank has failed and a new lower gradient bank
~ ment of material along a concave surface of rup- slope is present. As with a modified slump, once a
ture. This type of failure is unlike a modified failure has occuned, displaced rock creates turbu-
slump in that the failure zone is dish-shaped rather lence that may accelerate particle erosion.
' than a relatively flat plane (Figure 3.7). Slump The probable causes of slump failures are:
failures aze caused by shear failure of the underly-
ing base material that supports the riprap. As • The side slopes are too steep, and sliding
~ discussed by Schuster and Krizek (1978), the forces exceed the inertial forces of the riprap
rupture may not occur simultaneously over the and base material along a friction plane.
' failure area, but propagates from a local point. The
displaced mass, including the riprap, moves • Nonhomogeneous base material with
downslope beyond the original failure area onto layers of impermeable material that act as
' the surface of the riprap. A primary feature of a fault planes, particularly when subject tb
slump failure is the localized displacement of base excess pore pressure.
material along a slip surface. This is usually caused
' by excess pore pressure that reduces friction along • There is too much overburden at the top of
a fault line in the base material. The scarp at the the slope. This may be caused in part by the
head of the slump, located in both the base and riprap.
~ riprap material, may be almost vertical. With pro-
Modes and Couses of Bank failures 3 9
'
. . r
Figume 3.7 Failure caused by slump. (Adapied from BlodgeM and McConaughy 1986.) -
,
Scarp 7
r,~ ,
Displaced rodc and \ • - Base
base material . ' . ~ . " , i~ material
.r ~
~~^•~•i'C`i'~.
r' \ . . ` • ' Q ..K DISh'Sf18ped ~
' failure zone in
base material
r r~ w°~•t ~
_ . , • . . . , . , ~~~!a r '
• Channel bed . ' . . , ~Y•
• W ' &
MINEW,
'
~
3.6.5 FACTORS CONTRIBUTING TO e. Design discharge was too low.
RIPRAP FAILURES f. Inadequate assessment was made of
Four tYPes of riPraP failures (particle erosion, abrasive forces. '
g. Inadequate allowance was made for
translational slide, modified slump, and true slump) effect of obstructions.
have been discussed. The specific mechanism • Riprap material was improperly graded. i
causing failure of the riprap may be difficult to define because several factors, acting either indi- . Material was placed 'unproperly.
vidually or combined, may be involved. Several ~
- reasons for riprap failures are identified and • No filterblanket was installed orthe blanket
grouped below: was inadequate or damaged. .
~
• Toe of riprap was not keyed below depth of • Channel changes caused:
scour. a. Impinging flow. '
b. Flow to be directed at ends of protected
• Riprap particle size was too small because: reach.
a. Shear stress and/or velocity were c. Decreased channel capacity orincreased ,
underestimated. depth.
b. Inadequate allowance was made for d. Scour of tce of riprap.
channel curvature. ,
c. Channel geometry was not considered • Sliding forces exceeded resisting forces
in the design. because:
d. Design channel capacity was too low. a. Side slopes. were too steep. ,
3-10 Mocles ond Causes oF Bank Failures ~
'
b. Excess pore pressure decreased the .
' friction angle.
c. Rapid drawdown caused excess pore
pressure in the bank.
, d. Structural planes of weakness were
present.
e. Resisting force components of the bank
' were removed by toe scour and
undercutting.
'
'
' .
'
,
,
, .
~
~
~
r
~
~ ~ ~ Modes and Causes of Bank Failures 3-1 1
r
RECOMMENDED SOURCES FOR
ADDITIONAL INFORMATION ,
r
Biodgett, J.C. and C.E. McConaughy. 198.6.
Rock Riprap Design for Protection of
' Stream Channels Near Highway ,
Structures. Volume 2--Evaluation of . Riprap Design Procedures. U.S. ,
Geological Survey. Water-Resources Investigation Report 86-4128. Sacramento, _
Calif. ~
Fischenich, J.C. 1989. Channel Erosion
Analysis and Control. In Wcessmer, W. ~
and D.F. Potts, eds. Symposium
Proceedings Headwaters Hydrology..
American Water Resources Association. ,
$ethesda, Md.
Richards, K. 1982. Rivers, Form and Process in ~
Alluvial Channels. Methuen and Co. '
London, England.
imons Li and Associates. 1982. En 'neerin ~
S , ~ 8
Analysis of Fluvial Systems. Fort Collins, ,
Colo.
~
~
~
'
,
,
. ,
3- 12 . Modes and Causes oF Bank Failures
i
' CHAPTER 4
PROJECT PLANNING -
~
Given the many causes of bank erosion, the dictate the most suitable qualificadons or experi-
' range of potendal solutions, and number of con- ence required of the team.
trolling factors that can influence project success, The types and detail of data required to analyze
selecting a pracdcal solution to a bank erosion a bank stability problem are highly dependent on
' problem can be a fornudable task. Therefore, a the relative instability of the river and the depth of
systematic approach to the analysis and design of study needed to resolve the problem. More de-
bank stabilization solutions is needed. tailed data are needed when quantitative analyses
' A successful bank stabilization project begins are necessary, and data from an extensive reach of
within a framework of planning and design. Plan- river may be required to resolve problems in
ning is the orderly consideration and formulation complex and high-risk situations.
' of what is to be done and how it is to be accom- Information useful in beginning a project in-
plished. Project planning should include an evalu- vestigation include maps, aerial photographs, notes
ation of the genuine need for bank protection. This and photographs from field inspections, historic
' framework sets the scope and boundaries of the channel profile data, information on land-use ac-
planniAg activities, defines the kinds of activities tivities within the basin, and changes in stream
that will occur, and guides the technical planning hydrology and hydraulics over time. This infor-
, tasks. In its simplest terms, it provides the What? mation, especially data on changes in channel
Where? Why? When? and How? elements of any morphology, are important because changes in
construction and maintenance project. Fischenich river beds and banks rarely occur at a constant rate.
' (1989) provides an excellent discussion of various Changes in bank stability are often associated with
considerations and criteria for channel erosion an event, such as a flood, or a particular activity in
analysis and the subsequent selection and design the watershed or river channel. If the association
, of remedial measures. between bank instability and a causal activity is
The four stages and associated elements in the understood, the rate of change can be more accu-
~ design and construction of bank stabilization rately evaluated.
projects are outlined in Figure 4.1. In general The community Flood Insurance Rate Maps
terms, any bank stabilization project, whether new (FIRMS) and floodway maps, published by the
' or remedial, should include all of these elements. Federal Emergency Management Agency
(FEMA), should be reviewed early in the investi-
gation to determine if the proposed project site is , 4.1 PRELIMINARY INVESTIGATIONS Iocated within mapped flood hazard areas. This
information, in conjunction with a field reconnais-
. Bank stabilization projects should neverbegin sance, may strongly influence project feasibility in
, until the mode and cause of the erosion have been terms of cost and overall design.
clearly identified. A technically and economically
sound project can only be achieved by addressing
' the source of the erosion problem and not just the 4.1.1 FIELD RECONNAISSANCf
symptoms.
As mentioned in Chapter 1, it is strongly Specific project planning begins with a field
' recommended that a team approach be used when reconnaissance. The purpose of field reconnais-
developing or reviewing possible bank stabiliza- sance is to obtain information needed for analyz-
tion projects. The nature of the project will likely ing the bank failure and developing a solution.
' Some of the goals of a field reconnaissance are to:
4-1
, project Planning
'
Figure 4.1 Associaled elemenh of bank stabilization projecls. (Adapted kom Fschenich 1989.)
,
,
Field Reconnaissance L No action ~
¢z
c
z~
Not Feasible
~W
0. Z Problem Identification Conceptual Project
(Determine the cause Solutions Feasibility ,
and mode of failure).
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Fe"bie I
Design ARematives LData Collection
8 Analysis '
~
W o Select Propcsed ~
~ Altemative
,
Pertnit Applications
,
'
Final Design Plans Permit qPprovals ~
8~ Spec'~f'ications
z
~q Installation '
z
.
~
~ o Construction Inspection
z~ ~
rL.~
Evaluation ~
zp
F Inspect/Monitor
. F, ?
~ ¢ Longterm
d ti Site Managemerrt . '
z
0 MaiMenance
~
4.~ Project Planning '
i -
• identify the natural resources, faciliries, and/ large failure on a levee with ample 'maneuvering
' or structures at risk; room, for example, allows the use of larger, heavier
• identify the cause and mode of the failure of equipment than the same failure in a residential
the channel bank or bed; area with close-set houses. In addition to access
' • determine site constraints and opportunities; locations, the condition of access and staging
• develop preliminary design criteria and areas should also be noted. In some instances,
examine the need for special site studies; these areas may require restoration to pre-project
' and conditions. Disturbance to adjacent areas should
• evaluate the possible role of vegetative be minimized. Ecologically sensitive areas, in
systems in the solution. particular, should be identified and avoided. Per-
~ manent access for inspection and maintenance
Table 4.1 lists tasks that should be performed should be provided whenever possible.
' during a field reconnaissance of the project site.
4.1.3 FEASIBIUTY ANALYSIS OF PROJEGT
' 4.1.2 PROBLEM IDENTIFICATION AND ALTERNATIVES
CONCEPTUAL SOLUTIONS
Results of the prelirmnary mvestigation are
' As noted in Chapter 3, most bank failures used to determine whether to proceed to the next
occur from a combination of hydraulic and design stage. More than any other point in the
geotechnical factors. One factor, however, usually project, the preliminary determination of project
t is dominant. Only after identifying the mode of feasibility relies heavily upon the experience of
failure can the project designer begin to formulate the project team members.
potential solutions. When developing rolutions, a number of op-
' Usually, one or more potential solutions to the tions (including a"no action" alternative) will
problem may appear feasible. The initial selection likely be available. Selecting a practical solution is
factors are the mode of failure and the cause(s) of easier when following a systematic procedure.
' the problem. If a combination of factors are re- The process should be consistent, clear, and objec-
sponsible for the failure, the solution may require tive in comparing and selecting alternatives to
a combination of two or more techniques. ensure that a successful project is achieved.
' Whether vegetation is intended to fulfill struc- Project solutions should be evaluated accord-
tural, habitat, or other funcrions, full consideration ing to the following criteria (adapted from King
of its potential role should be an integral part of the County 1993):
, planning process. Neglecting the potential role of
vegetation at any stage of a project usually results • Policy and Regulations. The project should
in a lost opportunity to use its structural and be consistent with agency policies and
' biological functions in a meaningful way. Chapter regulations and should not conflict with
6 addresses the use of vegetation in bank stabiliza- regulations governing activities in the
tion projects. floodplain and the riparian corridor. Because
~ While it is generally more effective to address the requirements of various regulatory
the causes of erosion rather than its symptoms, agencies overlap, conflicts can arise. These
there are instances when the solution may be conflicts should be identified and resolved
, limited to treating symptoms. Restricted access as early as possible.
rights, available work space or other site con-
' straints, or project budgets may limit project alter- • Technical Feasibility. Feasibility analyses
natives from which to select a solution. are used to decide whether to proceed to the
The location and size of the project will influ- next stage. This includes the possibility of
' ence the selection of a stabilization methbd. A achieving expected results using current
4•3
' Project Planning
r '
TaWe 4.1 Field reeonnoissanca task lat
'
~ Measure the dimensions oF the eroded bank (lengih and width; top of bank to the toe; identify the ordinary high ~
waler mark).
~ Measure the distonce kom the top oF the eroded bank to nearby buildings or structures.
lxote and measure the width oF access areas (usually driveways, clearings around sides oF buildings or existing ~
a leV9e=).
F 4 Note the general characteristics of the river in the project area. This includes general gradient through the project ~
reach (is it steady, or does it change signiFicandy up- or downstream oF the site?), channel constrictions, channel
width (width/depth ratio); and condition of banks up- and downstream of praject area (i.e., cre they eroding or
stable?). ~
~ ~ d cation i of sedmert trasport choracte~iscs duringe l~igh l distribution and median size class). This provides
an
,
6 Note the size of the stream or river, direction oF Aow, ond Now patterns. IF possible, make several obsenations at
~ both (ow and high Aows. Does water Flow directly into the eroded bank? Does water flow around a bend? Are
there eddycunerrts from upstrecm objects? ~
eatures ffect cue ents~~~ints such as bedrock, bridge structures, large boulders or debris jams and how these
~ a
F
~
a and tc~ de on of la ge tr~ees near the i e od ed bank (note the Ixi cnd
at on ppro ~mate mber~eThis i nZFeo ation
is useful in defining the type of system to be used, completing environmental checklists and permit applications. ,
a Note Fish and wildlife use and/or habitat in the area. In addition to improving the design, this inFormation is used
For completing environmenrol checklists and other documents. ~
~ O On the eroded bank, note the general ypes oF soil (e.g., gravel, organic, clay, silt, large cobbles) and the
arrangement oF soil layers iF composite banks are present.
Note the condition oF the soils in the access area and where heavy equipment will be working. Are soils wet and ,
soft8 Will some kind of hardened surface (e.g., crushed rock) be required? Is there a staging area for equipment
and material? ~
ePat sketch
def~ne the relato sh~between the steame aea ts oF er~ osiont ex~ine helpful
or
access ~oads, and
property bo to undaries. A brief search for property corners and road monuments 9 stru useFul for the survey and for ~
preparing the base mop.
Establish photo-points and take photographs. Photographs should be composed ro aid the designer in completing ~
base maps and designs. The Ixation of the pho►o-points should be noted on base maps and design plans.
Photographs should also be submitted with permit applications and/or exemption requests. Show the extent of the
erosion, its relationship to buildings or other structures, top of bank, and the existing stream conditions (boulders,
gravel bors, debris jams). Photograph access sites, and condition oF the banks upstteam, downstream, and ,
opposite the project site.
Examine existing bank conditions For points to begin and end the projed. Starting locations will need anchor sites '
or other protedion. The project should end either on a straight bank or an existing stable feature.
F, 5 Prepare an in-Field, preliminory cost estimate. Also consider costs For clearing, access, easements, and permit fees.
. '
q,4 Project Plonning ~
i
scientific and engineering principles and 4.2 INTERMEDIATE PROJECT DESIGN
' methods. Material availability, required
construction equipment, construction 4.2.1 DATA COLLKTION AND ANALYSIS
methods, project life, and aesthetics should
' also be considered.
Although most of the analyticai data necessary
~ Risk and Hazard Reduction. The effect of for project design should be collected during the
' the project on public safety and health, and site investigation, some data must be acquired
fish and wildlife resources, should be from other sources. Comparison of aerial photos,
' evaluated both upstream and downstream for example, can be invaluable for documenting
' of the project site. The project should have rates of erosion and channel features up- and
a beneficial effect on public health and downstream of the project site. Aerial photographs
safety. This includes protecting a threatened record much more ground detail than maps and are
' structure or facility or reducing aquatic frequently available at five-year intervals.
habitat or water quality impairments from Many commonly available maps (e.g., flood-
the continued input of sediment. plain, topograpluc, geologic, soil, and land use)
' provide information essential for project design.
• Environmentallmpacts. Bankstabilizadon Topographic and soils maps are invaluable for
solutions can have both positive and negative identifying the general characteristics of the site.
' impacts on fish and wildlife habitat, adjacent Unstable river reaches up- and downstream of the
wetlands, water quality, and other public project site can create instability at the site. Area
resources. The project should minimize maps are useful for locating unstable river reaches
' negative impacts and enhance these relative to the site. Vicinity maps help identify
resources whenever possible. These more localized problems.
t objectives can be conflicting and may not Hydraulic and hydrologic information such as
always be met. Individual project constraints discharge, stage, velocity and flood records or
may limit the fulfillment of various estimated (i.e., modeled) flows are required to
' environmental objectives. understand the flow characteristics at the project
site. FEMA flood insurance studies, U.S. Geo-
Figure 4.2 illustrates the process of selecting logical Survey publicadons, or analyses completed
' and evaluating project solutions when applying by local agencies are sources for this infortnation.
the criteria described above. If available, historic river profile data provide
An additional factor often considered is eco- information on channel stability. Stage trends at
, nomic feasibility. When planning any project, gauging stations or the comparisons of streambed
Orsborn (1982) advises that the planning process elevations at structures (pre- and post-constroc-
proceed entirely through the generation of con- tion) will provide information on changes in river
, ceptual solutions before costs are considered. profile. As-built bridge data and cross-sections,
Projects should not be designed to a roughly esti- for example, are frequendy useful in determining
mated dollar amount. Force-fitting a solution to a changes stream profiles over time. Structure-in-
~ fixed amount is an arbitrary constraint that often duced scour should be taken into consideration
results in a high risk of project failure. If a concep- when such comparisons are made. In some situa-
tual solution appears feasible, planning proceeds tions, sediment samples from the bed and banks of
' to intermediate project design. the river may be needed for particle gradation and
composition analysis.
~
~
Project Planning 45
~
N '
Figure 4.2 Evalualion and seleclion of project solulions. (Adapted from King County 1943.)
,
,
IDENTIFY ALL REASONABLE SOLUTIONS FOR THE PROBLEM SITE ~
AND EVALUATE EACH ACCORDING TO THE FOLLOWING CRITERIA:
,
POLICY/REGULATIONS: Do the benefits of the ,
Is the project compatible with No No Project
. project justify seeking a
existiny agency policies and/or other variance or exem tion? dropped
jurisdictional regulations? p
~
Yes Yes
~
TECHNICAL FEASIBILITY: No Projed
Is the project technically feasible? dropped ,
Yes ~
RISK/HAZARD REDUCTION: '
Does the projed significantly reduce No Project
the risk to the public heatth & safety dropped
and/or fish & wildlife resources? '
Yes '
ENVIRONMENTAL IMPACTS: Do other benefits of the ,
Are the net environmental impacts project outweigh negative N Project
. of the project positive or environmental impacts? dropped ~
insignificarrt?
Yes Yes ~
COMPARE ALL SOLUTIONS THAT REMAIN AND ,
SELECT THE ONE THAT BEST MEETS THE CRITERIA.
. . ~
~
~ Project Planning '
' .
The following detailed survey information is simple as a few computadons and a qualitadve
' typically generated during intermediate project analysis. The purpose of the analysis is to verify
design stage: the mode and cause of the failure, and to determine
the threshold values for the parameters of impor-
' • Control Baseline. Baseline should be tied tance. Table 4.21ists the types of technical analy-
to National Geodetic Vertical Datum ses that may occur during the investigation of a
monuments (street, mad or highway) if bank erosion problem. The degree to which these
' possible. Baseline surveys can be tied to analyses are undertaken depends on the complex-
property corners (if present) if other ity and environmental sensitivity of the stream
monuments are not available. If no reach. Computation of boundary shear stress, for
' monuments are available, use an assumed example, may be necessary to determine if it
datum and set a temporary benchmark. exceeds the allowable value for the bank material.
A slope stability analysis should be conducted if a
' • Cross-Sections. Cross-sections should be geotechnical failure is suspected. Once these analy-
located along the length of the project area ses have been completed, the specific design op-
at sufficient intervals to provide accurate tions discussed in Chapter 7 can be considered.
' detail for plotting and quantity calculations. When developing project design alternatives,
Define the top of bank, grade breaks, toe of project costs and regulatory criteria must be con-
bank, and streambed geometry. Access to sidered. Project costs should be based on a detailed
~ river channels with deep, fast flows may be design that includes both initial and long-term
difficult and dangerous. In these cases, costs. Both the project's costs and benefits should
, partial channel cross-sections may provide be estimated to deterniine if a cost effective solu-
sufficient information on reach tion exists. An economic analysis must account
characteristics. for initial costs for design and constivction and the
' long-term costs of operation and maintenance.
• Topographic. Locate corners of The acquisidon of adequate rights-of-way and
buildingsand other structures, fences, large easements to ensure future maintenance access
~ - trees and shrubs, and other significant should be inidated in during the design stage. Cost
features at the project site. Identify the of acquiring land or easements must be incorpo-
location of wells, sewers, septic tanks or rated into the overall project costs.
, other utilities that usually restrict access or
construction activities. Note property
corners if readily identifiable. Note the 4.2.2 PERMIT APPUCATIONS
~ location of gravel bars, large boulders, large
downed trees, large stumps and other debris. Contact with regulatory agencies, such as the
Washington Departments of Fisheries (WDF) and
' The quality and quantity of the fish and wild- Wildlife (WDW), should be initiated early in the
life habitat existing at the project site should be design process. In King County, for example, a
evaluated. This evaluation may include determin- pre-application meeting with the technical review
' ing the types of habitat present, life stages and staff of the Land Use Services Division (LUSD)
species use of the area, seasonal variations in the and the Environmental Division (ED) can be ar-
available habitat, and other limiting factors. This ranged to discuss the project approach and identify
' evaluation is used to evaluate potential adverse permit requirements.
effects orenhancement opportunities at the project The King County Sensirive Areas Ordinance
~ site. (SAO) regulates activities in environmentally sen-
After this information is compiled, analyses of sitive areas such as floodplains, streams, wetlands,
the existing conditions are performed. This may steep slopes, and buffer zones. This ordinance,
' be as involved as mathematical modeling, or as adopted in 1990, is generally more restrictive than
, Project Planning .4-7
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4-8 Project Planning '
'
many other local, state or federal regulations. At a minimum, the plans and specifications should
' Avoiding delays in the permit approval process include:
involves the careful consideration of SAO re-
quirements during the initial conceptualization of • description of the work;
' the project. By incorporating the SAO require- • contractual clauses;
ments into the design, the designer can minimize • material descriptions and specifications;
the review effort and the associated processing • construction methods and tolerances;
' time. Moreover, when a project is developed to • the construction schedule;
comply with the more restrictive conditions of the • access, right-of-ways, and easements; and
SAO, it is more likely to comply with the less • plans, typical sections, and a location map.
' restrictive requirements of other agencies. A use-
ful approach is to apply the mitigation sequencing Since rivers are dynamic systems, the designer
as described in the SAO. Applying mitigation should anticipate changes in field conditions be-
' sequencing throughout the design process (i.e., tween the time when the plans and specifications
avoiding, minimizing, rectifying, reducing, com- are initiated and when construction begins. The
pensating and monitoring for environmental im- plans and specifications should to be flexible to
' pacts) will create project designs that are compat- allow for change orders in the field. Final plans
ible with regulatory requirements and policies. should address appropriate inspection and tests to
~ The types of permits, fees and processing ensure that suitable materials and construction
times vary widely depending on the project. More practices are used.
detailed information on various regulations, per- The acyuisition of rights-of-way and ease-
' mit requirements, and application procedures is ments should be finalized in conjunction with the
discussed in Chapter S. design plans and specifications. In addition, all
permit approvals must be obtained and copies
' available on-site before construction begins.
4.3 FINAL DESIGN
, The topics included in the following sections 4.3.2 PROJECT CONSTRUCTION
are discussed in detail in Chapters 6 through 9.
These discussions provide a brief summary of As discussed in detail in Chapter S, nearly all
, these elements of the project planning process. bank stabilization projects will require some level
After completing the Preliminary Investiga- of construction planning and installation. Project
tion and Intermediate Project Design, the pre- construction can be as simple a,s planting vegeta-
~ ferred course of action should be apparent. At this tion, or as complex as stabilizing a bank with an
point, the project enters Final Design. This in- integrated system of vegetation and structural com-
cludes the preparafion of plans and specifications, ponents. The amount of on-site supervision during
, detailed environmental impact analysis and miti- construction varies with the scope of the work.
gation design (if required), permit acquisition, Priorto the start of construction, it is helpful to
project construction, operation, inspection and have an pre-conswction conference with repre-
' maintenance of the facility. sentatives of permitting agencies, inspectors, and
contractors. This conference, whether informal or
formal, will help clarify project designs, installa-
~ 4.3.1 PLANS AND SPECIFICATIONS tion techniques, and pernvt conditions.
Flexibility in project design and installation is
~ Preparing design plans and specifications for a essential during construction. An ideal situation is
bank stabilization project ensures that the com- when all members of the design team are fre-
pleted product meets all of the project objectives. quently on the job site during construction. If the
~ designers are present, the contractor or job super-
Project Pianning 4-9
'
visor can respond to unforeseen developments RECOMMENDED SOURCES FOR
that could otherwise create project delays and cost ADDITIONAL INFORMATION ,
overruns.
,
4.4 POST CONSTRUCTION Coppin, N.J. and I.G. Richards. 1990. Use of
Vegetation in Civil Engineering. ~
Continued reliable performance of any bank Butterworths. London, England.
stabilization project requires a sound inspection
and maintenance program. As part of long-term Fischenich, J.C. 1989. Channel Erosion
site management, a project site should be in- Analysis and Control. In Woessmer, W. '
. spected at least annually, and preferably during and D.F. Potts, eds. Symposium
and after major flood flows. Damage to the struc- Proceedings Headwaters Hydrology. ~
ture or physical changes to the channel should be American Water Resources Association.
noted. During low-water periods, the lower bank Bethesda, Md.
and general project conditions including plant ,
survival and the need for replacement should be
noted. An inspection checklist helps ensure that
inspections are uniform and thomugh. ~
When an inspection reveals damage to a struc-
ture or a general state of deterioration, mainte-
nance measures should be initiated. As with all
~
constructed facilities, bank stabilizarion structures
or systems will eventually require maintenance.
Chronic problem areas requiring continuous main-
tenance should be evaluated to decide if redesi g n ~
and reconsttvction are warranted. ~
'
'
~
'
'
'
4-10 Projecf Planning '
' .
' CHAPTER 5
PERMITS AND POLICIES
ro'ect re- 5.1 AN OVERVIEW OF PERMITS
'
Implementing a bank stabihzation p~
quires a thorough understanding of the regulations
' of the local, state and federal
that may affect such a project. Regulatory require- A summary ments, policy interpretations, and scientific knowl- permits that may be required for riverine projects
edge relating to the riverine environment are con- within King County is presented in Table 5.1.
' tinually evolving. Before the 1970's, when most The interrelated permit reviews that exist be-
of King County's major river projects were de- tween various regulatory agencies should be
signed and constructed, only limited floodplain noted. Shoreline permits and State Environmen-
' and natural resource protection regulations ex- tal Policy Act (SEPA) processes, for example,
isted. In recent years, the variety of regulations has are listed in Table 5.1 under both "Local" and
' increased to provide greater resource protection "State" jurisdiction. These are state regulations
from projects proposed in and along rivers. administered by the local agency, in this case,
This chapter discusses the regulatory aspects King County. Each Shoreline permit application
~ of implementing proposed projects. It includes an and SEPA checklist requires a review by the state
overview of King County, Washington State and or Tribal agencies prior to the final permit ap-
federal pemuts, discusses conflicting regulatory proval by the local agency. Similarly, a Hydrau-
' policies of different agencies and reviews regula- lic Project Approval (HPA) can only be ap-
" tory issues associated with public funding and proved by the Washington Departments of Fish-
assistance programs. eries and Wildlife af,.;r SEPA requirements are
' The designer should be aware of the permit satisfied.
requirements and the current interpretations of Interdependent permits also exist between
policies that can affect project design and funding. some state and federal regulations. The Section
, This chapter is not a substitute for reading the 10 and Section 404 permits require a Coastal
published regulations; it simply paraphrases and Zone Management Consistency Determination
summarizes these regulations. Before initiating a and a 401 Water Quality Certification from the
, project, review the appropriate regulations and Washington Department of Ecology (Ecology)
contact the regulatory agencies forthe latest policy prior to permit approval by the U.S. Army Corps
interpretations and permit requirements. A listing of Engineers (Corps). HPA and Shoreline per-
, of agency and tribal contacts is provided in Appen- mits may also be required in conjunction with
dix B. Communication with these agencies should Corps permits.
be initiated early during project planning and From the timelines listed in Table 5.1, it is
, should continue throughout the design, installa- obvious that the time required to obtain all re-
tion, post-construction monitoring and long-term yuired project approvals can be lengthy. The
maintenance phases of the project. types of permits required and the length of the
, All local, state, and federal agencies should review process varies with the complexity of the
consult with tribal governments when considering project and the environmental sensitivity of the
, projects on tribal lands or when proposing projects site. The lengthy timelines emphasize the fact
on non-tribal lands that may affect treaty-reserved that permit processing is a significant element in
resources or areas. Several tribes in the King the overall project schedule. Projects developed
~ County acea, including the Tulalip Tribes, the with an awareness of current regulations can
Muckleshoot Indian Tribe, and the Puyallup Tribe minimize the time required for obtaining per-
of Indians, have lands and continuing treaty inter- movide s further tinformaion about he ctions
ts
' ests in natural resources. p
summarized in Table 5. 1.
S-1
, Permits and Policies
4 '
Table 5.1 tZE=!ts and fheir generol processing timelines for King Couny, WashingFon SfaM and
'
JURISDKTION PERMIT TIMELINE
LOCAI) ,
oF ing Counly ~ Clearing/Grading permit 1-12 monlhs
Erniron~mento r ices $ensitive Aceas Ordinance 3-6 monlhs ,
(SAO) Variance/Public
Exceptio^
'locol" Shorelines Subslantia) 3-6 monfhs , I
Development Permit (SDP)
"local" Shorelines CondiHonal 6-9 monihs (9-12 monlhs
Use Permif (CUP) iF public hearing is required) ,
'local" Shoreline Variance 6-9 moMhs (9-12 monfhs
iF public hearing is required)
'local" Shoreline Exemption 1-2 months (public hearing required)
,
'local' Sloie Ernironmenbl If DNS or MDNS, 1-12 monfhs
Poliry Acf (SEPA) Checklist (3 month werage). If D5, an EIS is
required; thsn 3 moMhs-3 yeots ~
(18 month avenoge).
STATE
Vorious skfe agencies SEPA determination & chedclist, If DNS or MDNS, thenl -12 I
or EIS review by state and months (3 monlhav~age).
Tribal agencies If DS an EIS is required;
than 3 months-3 yeaa (18
month aremge). ~
Depr. of Ecology Shoreline SDP .30 days
Shoreline CUP 60 days
Shoreline Varianae 60 doys
Coasal Zone Manogemenr A5 days For iederol acfivifies; '
CeAifioafion/Delermirwtion 6 months 6or other permits
401 Wakr Glualily CerfiFioation Processed in conjuntlion
wilh Gorps Sedion
101404 permils.
Depts. oF Fisheries Fiydmulic Project Approval Up t0 45 days From aompletion '
and WiIdliFe of 1he SEPA roview process
ond receipt oF a oompleted
opplioafion.
Depr. of Natuml Resouroes Aquotic Lond Use Autl+orization 3-6 month
,
FEDERAL
Corps of Enginaen Seclion 404 Permit Le1Fer oF permiuion, 20 days. ,
. Seciion 10 Permit Nationwide, ZO dars.
Individual, af least 6 monlhs.
Environmenlal 401 Wobr Qwlily Certifioolan Pracossed in oonjunction ~
Prolection Agency with C«ps Ssdion
101404 permils.
~ Pormits for incorporaled eities wilhin King Couny ane nd induded. ~
• '
5.2 Permits ond Policies '
5.2 KING COUMY REGUTATIONS pede flood waters. Similarly, the ordinance pro-
. hibits filling in the floodplain unless "compensa-
' Local govemments often have permits--or are tory storage" is created for the flood storage lost
responsible for implementing state and federal through filling. This new, excavated storage vol-
requirements--that affect bank stabilization ume must be equivalent to the amount of flood-
' rol'ects. This section, and Sections 5.3 through plain filling and also connected hydraulically to
P
5.5, summarize the regulations and permits re- the filled area.
' quired for projects in unincorporated King County. With some exceptions (e.g. enhancement), the
Permits for bank stabilization projects pro- SAO also prohibits alterations to wetlands, streams,
posed for King County rivers and streams are and their buffer zones. Approved alterations to
' obtained from the Department of Development wetlands and their buffers require a mitigation
and Environmental Services (DDES). Specifically, plan. Other special studies including habitat value,
two divisions within the DDES review project hydrology, erosion and deposition, and/or water
' proposals: the Land Use Services Division (LUSD) quality studies may also be required.
and the Environniental Division (ED). The LUSD Buffers width requirements for wetlands and
is responsible for administering the 1990 King streams vary from 25 to 100 feet depending on the
1 County Sensitive Areas Ordinance (SAO) and the class of wetland or stream. Buffers for steep slope
1978 King County Shoreline Master Program. and landslide hazard areas are a minimum of 50
The ED is responsible for administering require- feet. These widths may be reduced if adequate
' ments of the 1983 State Environmental Policy Act protection is demonstrated through a special study.
(SEPA). These regulations (the SAO, Shoreline
' Master Program and SEPA) are described in detail
below. The SEPA process is discussed in Section 5.2.2 SHORELINE MASTER PROGRAM
5.5.
' King County adopted its most recent Shore-
line Master Program in 1978 to comply with the
5.2.1 SENSITNE AREAS ORDINANCE Washington State Shoreline Management Act
, (SAO) , (SMA). The SMA (Revised Code of Washington
[RCW] 90.58) was adopted in 1971 to protect
The SAO (King County Code 21.54) regulates shorelines of the state (shores of large lakes, the
' activities in environmentally sensitive areas such marine areas of Puget Sound, and other major
as floodplains, streams, wetlands, steep slopes and waterways). Shorelines of the state include riveis
buffer zones. Maps of sensitive areas in King and streams that have a mean annual flow of 20
' County, published as the Sensitive Areas Map cubic feet per second or greater, and lakts 20 acres
Folios, are available through the Environmental or more in size. King County jurisdiction over
Division: This revised ordinance, adopted in Sep- shorelines of the state includes those lands extend-
' tember 1990, is generally more restrictive than ing landward for 200 feet in all directions as
other associated local, state or federal regulations. measured on a horizontal plane from the ordinary
As a result, attention to the requirements of the high water mark. This includes the 100-year flood-
' SAO is very important in avoiding delays in per- plain and associated wedands.
mitting. The SMA requires cities and counties to adopt
The SAO contains regulations that will affect local shoreline master programs that include poli-
' most bank stabilization projects. For example, the cies and regulations for land use in shoreline areas.
ordinance states that projects within the 100-year Under the County's Shoreline Master Program,
floodplain must not cause any increase in the shorelines of the state are designated as "Urban,"
' elevation of the 100-year flood. This "zero-rise" "Rural," "Conservancy," and "Natural" The re-
requirement means, in effect, that projects con- strictiveness of the shoreline regulations depends
' structed in the 100-year floodplain must not im- on the designation placed on the area. For ex-
5-3
' Permits and Policies
. ,
ample, regulations for Natural areas are more The permit process will vary depending on the
restrictive than those for Urban areas. type of project being proposed. The County re- '
King County cannot issue a permit that is view staff will determine what permit process will
contrary to the goals, policies, and regulations of apply to fhe proposed project and what types of
its Shoreline Master Program. The requirements information (such as a stream survey, wetland '
of the Shoreline Master Program must be consid- report, shorelines plan, or mitigation plan) will be
ered when issuing permits required by the County's required.
SAO. For this reason, the permit processes for When contacting the Grading Unit to schedule ~
implementing the SAO and the Shoreline Master the pre-application meeting, the applicant should
Program are closely related. These pernuts (i.e., request:
Clearing/Grading and Shorelines) are discussed in '
Sections 5.2 and 5.3 below. • a pre-application review application with a
fee schedule; ,
• the names of the County staff assigned to
5.3 KING COUNTY CLEARING/ the review, and ' '
GRADING PERMIT • attendance at the pre-application meeting ~
by sensitive areas, grading, and shorelines
Prior to initiating the County permit process, it staff responsible for the review.
is important to understand the relationship be- '
tween the- Clearing/Grading and Shoreline Per- The pre-application meeting should occur a
mits. Because shorelines of the state are environ- minimum of one to three months prior to
mentally sensitive areas, these two permits have a pemut submittal. At the meeting, the project ,
coordinated review process. Permit applications applicant should:
are reviewed by the Grading, Sensitive Areas and
the Shorelines Units in the Land Use Services • establish contact with the responsible ~
Division. County review staff;
The Clearing/Grading Permit is required for • provide copies of preliminary design
any land-use activity would include cutting or drawings and a written description of the '
removing vegetation and/or excavating, filling, project rationale;
removing of earth material within a sensitive area. • request information on any additional sub-
This permit is the mechanrsm through which con- mittal requirements and the review '
ditions are applied to ensure compliance with the sequence;
SAO, SEPA, and other applicable ordinances. • schedule field visits as necessary; . '
Because the Clearing/Grading Permit application • determine the shorelines designation (i.e.
initiates the review process, it is described first and Urban, Rural, Conservancy or Natural) at
followed by a description of the types of Shoreline the Zoning Counter. '
Permits.
The review process begins when the applicant After the applicant has compiled the informa-
contacts the Grading Unit to request a pre-applica- tion requested, the project will be reviewed for '
tion meeting. The purpose of this meeting is to compliance with the County regulations. The re-
acquaint the County staff with the proposed project, view time can vary considerably depending upon
to provide evidence that will justify a particular the project size and complexity, and the number of '
type of review, and to establish the pernut process reviewers involved. Incoiporating the requirements
for the proposed project. At this initial step in the of the SAO and Shoreline Master Program early
process, the applicant is alerted to any problems in the design process can greatly minimize the '
that may be encountered in gaining approval of the County's review and processing time.
proposal. The Grading Unit staff processes project ap-
plications in the following order: '
S-4 Permih ond Policies '
-
' Y
• Exemptions (as defined in King County 5.4.1 SHORELINE SUBSTANTIAL
' Code [KCC] 21.54) DEVELOPMENT PERMIT (SDP)
a. Fmm the grading code.
b. From the sensitive areas code. The SDP is required for any "substantial de-
' velopment" occurring within 200 feet of a shore-
. permits line of the state. Substandal development includes
a. Emergency Exception; mitigation is any development with a total cost or fair market
' required. value of at least $2500, or any development which
b. Public Agency Exception; mitigadon materially interferes with the normal public use of
and a public hearing are required. the water or shoreline. "Development" includes
' c. Approved Alterations; limited construction or exterior alteration of structures;
midgation may be required. dredging; drilling; dumping; filling; removal of
sand, gravel, or minerals; bulkheading; driving of
~ A maintenance excepdon from the Clearing/ piling; placing of obstructions; or any project of a
Grading Permit is provided under King County permanent or temporary nature which interferes
Code 16.82.050 for routine clearing or grading with the normal public use of the surface of the
' activities performed by a public agency for main- waters overlying lands subject to the Shoreline
tenance of publicly owned facilides (such as flood Management Act at any water level.
, control or other surface water management facili- Because SDPs are issued by local govern-
ties). For emergencies that threaten public health, ments, the review time varies with the local pro-
safety and welfare, exemptions can be granted cess. For King County, the processing time ranges
' under the SAO (KCC 21.54.030) through an ad- between 3 to 6 months. The minimum time re-
ministrative ruling by the Director of the DDFS. A quired by state regulation before construction may
project exempt under KCC 21.54.030, however, begin is 72 days from the date that a complete SDP
, may not be exempt from clearing and grading application is submitted to the local government.
requirements underthe Grading Code (KCC 16.82). Permit fees, which are set by local government,
If no issues related to requirements of Shore- vary widely.
~ line Master Program exist, a public agency excep- SDPs are subject to appeal by applicants, gov-
tion or SAO variance for any alterations that do not ernment agencies, or the public. Appeals must
conform to the requirements of King County Code occur within 30 days of the date of filing of the
, 21.54 is granted. permit with Ecology. Appeals are heard by the
State Shorelines Hearings Board.
Activities that are exempt from the SDP pro-
, 5.4 KING COUNTY SHORELINE cess include:
PERMITS • development with a the total cost or fair
, Permits issued under the Shoreline Master market value of less than $2500;
Program include the Shorelines Substantial De- • maintenance and repair of existing lawfully
' velopment Permit (SDP) and the Shorelines Con- established structures;
ditional Use Pernut (CUP). These permits ensure • construction of a protective bulkhead on
that development in shoreline areas conforms with property occupied by a single-family
' the King County Shoreline Master Program and residence;
the goals and policies of the SMA. In addition, the • construction and practices necessary for
Shoreline Master Program allows for a Shoreline farming, agricultural, and ranching
~ Variance and a Shoreline Exemption in certain activities; and
special circumstances. All of these permits are • construction by the owner, lessee, or
described below. contract purchaser of a single-family
'
' Pertnits and Policies S-S
u '
residence (and private dock) less than $2,500 the cumulative impacts of granting additional simi-
in fair mazket value for his/her own use. lar requests is required before a Conditional Use '
Permit can be approved.
Emergency construction necessary to protect Uses and activities classified in the local SMP
property from damage by the elements is exempt as requiring a CUP must obtain approval of a CUP '
from the requirement for an SDP. An "emer- even if the fair market value of the development is
gency" is defined in Washington Administrative less than $2,500. CUPs are issued by local govern- ,
Code [WAC) 173.14.040(d) as "an unanticipated ments, subject to Ecology approval. King County
and imminent threat to public health, safety, or processes CUP in 6 to 9 months. If a public hearing
environment which requires immediate action is required, the processing time may extend to 12 '
within a time too short to allow compliance with months. The minimum time period required by
the procedural requirements of the Shoreline Man- state regulation before construction can begin is
agement Act." 90 days from the date that a complete application ~
is submitted to local government.
CUPs are subject to appeal by applicants,
5.4.2 SHOREUNE CONDITIONAL USE government agencies, and the public. Such ap- ~
PERMIT (CUP) peals are heard by the State Shorelines Hearings
Board. Appeals must be filed within 30 days of the
A CUP provides more control and flexibility date of final action by Ecology. Permit fees, which ~
in implementing the policies and regulations of the are set by local governments, vary widely.
local Shoreline Master Program and SMA. CUPs
generally involve uses and activities over-water '
and other environmentally sensitive shoreline re- 5.4.3 SHORELINE VARIANCE
sources. As a result, they typically receive a higher
level of review by King County and the State A Shoreline Variance is intended to grant ,
Department of Ecology. relief from specific bulk, dimensional or perfor-
A CUP is required for uses and activities mance standards set forth in the local Shoreline
classified or set forth in the applicable SDP. A Master Program. This variance applies where there ~
CUP may be authorized if the applicant can dem- are extraordinary or unique circumstances with
onstrate that the proposed use is: the property such that strict implementation of the ,
standards will impose unnecessary hardship on
• consistent with the local Shoreline Master the apphcant orthwart the policies of the Shorehne
Program and Shoreline Management Act; Management Act. Iiregular lot shapes, sizes, natu-
• will not interfere with the normal public use ral features, or uniyue conditions specifically re- ,
of the shoreline; lated to the property are typical problems that may
• will be compatible with other uses in the justify a variance. Activities permitted by the '
area; variance can only occur in a manner that the public
• will not cause unreasonable adverse effects interest sha11 suffer no substantial detrimental ef-
to the environment; and fect.
• will not cause substantial detrimental effect The burden of proof is on the applicant to
to the public interest. demonstrate the following:
Uses not classified in the Shoreline Manage- • strict application of the standards precludes '
ment Program may also be authorized through or significantly interferes with a reasonable
issuance of a CUP, provided that, in addition to the use of the property; ~
above criteria, extraordinary circumstances exist a hardship exists that is the result of unique
which preclude reasonable use of the property in a conditions related to the property and not
manner consistent with the SMP. Consideration of from the applicant's own actions; '
5.6 Permits and Policies '
'
• the project design is compatible with and cessing time for this exemphon is approximately 1
t will not adversely affect neighboring uses to 2 months. A public hearing is requiring before
of the shoreline environment; an exemption can be issued.
• the variance dces not constitute a grant of
' special privilege and is the minimum
variance necessary to afford relief and will 5.5 STATE ENVIRONMENTAL POLICY
have no substantial detrimental effect on qCT (SEPA)
' the public interest.
The SEPA (RCW 43.21; WAC Chapter 197-
Variance requests for projects located 11) requires that the state and local govemments
' waterward of the ordinary high water mark, must consider the environmental impacts of certain
also demonstrate that the public rights of naviga- public and private projects. The goal of SEPA is to
tion and use of the shoreline will not be adversely protect the environment from significant adverse
' affected. The cumulative impacts of additional impacts due to development or other land-use
similar actions must also be considered. actions.
Variances are not meant to allow an otherwise The SEPA does not require specific permits•
' prohibited use. Economic status, deed restrictions, Rather, it requires that a specific process be fol-
lack of planning or construction foresight, or other lowed to idendfy environmental impacts of a pro-
' actions by the applicant which create a need for a posed project. Based on information on the project
variance are not valid justifications for granting and its likely environmental effects, the County's
variances. Environmental Division will make a series of
tShoreline variances are issued by King County decisions. These decisions include if the project
and are subject to Ecology approval. Variances can proceed as proposed, if modifications are
may be appealed by applicants, government agen- necessary to mitigate impacts, or if additional
r cies, and the public within 30 days of final action information and analysis is necessary before a
by Ecology. Such appeals are heard by the State decision can be made. Public review and comment
Shorelines Hearings Board. No provisions have periods are required. SEPA rarely results in a
' been established for issuing a variance during project being rejected entirely; rather, it seeks to
emergency conditions. modify the proposal in ways that lessen its effect
The time involved in obtaining a variance on the environmental.
' depends on the local review process. For King Compliance with the SEPA process can affect
C o u n t y, a v a r i a n c e c a n b e p r ocessed in 6 to 9 the approval of other permits. A project requiring
months. As with the CUP, a public hearing may be a Shorelines permit or a HPA (discussed later in
~ required for a Shoreline variance, potentially ex- Section 5.6) must comply with the SEPA process.
tending the processing time to 12 months. The Because most bank stabilization projects will re-
minimum time required by state regulation before quire one or both of these permits, it will also be
~ construction can begin is 90 days from the date subject to SEPA.
that a complete application is submitted to local SEPA mandates that a lead agency (e.g. the
government. Fees for a variance, which are set by King County Environmental Division) determine
~ local government, vary widely. if a proposed project will "significantly affect the
quality of the environment " This deternnination,
which is based on responses to a standardized
~ 5.4.4 SHORfLINE EXEMPTION checklist, is called a"threshold deternunation:'
The project applicant begins the SEPA process by
' An exemption from Shorelines permits is al- submitting the completed checklist to the lead
lowed under WAC Chapter 173.14.040for projects agency for a threshold determination.
involving normal maintenance or repair of an If the proposed project will have a mimmal
~ existing, legal structure. The King County pro- environmental impact, the agency issues a deter-
Pernnits and Policies 5-7
,
'
mination of non-significance (DNS). If the project 5.6.1 HYDRAULIC PROJECT APPROVAL
has an environmental impact but the impact can be (HPA) /
mitigated through other actions, a mitigated deter-
mination of significance (MDNS) is issued. The HPA is required by any person orgovern-
Projects likely to have a significant impact receive ment agency seeking to perform any work that will '
a determination of significance (DS). These use, divert, obstruct, or change the natural flow or
projects undergo more extensive review which is bed of any of the salt or fresh waters of the state. It ~
documented in an environmental impact state- is intended to protect fish life in waters of the state.
ment. The Washington Departments of Fisheries
In the 1983 amendments to SEPA, new lan- (WDF) and Wildlife (WDW) jointly administer ~
guage adopted under RCW 43.21C.060 allows the State Hydraulic Code (RCW 75.20.100 and
agencies to consider mitigation measures when 75.20.103). Applications are coordinated so that
making threshold deternunadons. A MDNS may applicants only deal with one agency. WDF typi- '
be granted if the applicant clarifies or changes the cally takes the lead for marine and freshwater
proposed project, and adequate mitigation mea- areas that support anadromous salmonids. WDW
sures for project impacts aze possible. The SEPA takes the lead for all other state waters. ~
rules state that if a"proposal continues to have a The Hydraulic Code requires WDF or WDW
probable significant adverse environmental im- to grant or deny approval within 45 calendar days
pact, even with mitigation measures, an EIS shall of the receipt of a complete application and notice ~
be prepared." of compliance with any applicable requirements
Processing time for a SEPA deternunation of SEPA. Compliance with SEPA is required prior
depends on the lead agency and the amount of to the issuance of an HPA. State laws require that ~
analysis required for the proposal. If a DNS or the agencies strive to process hydraulic project
MDNS is issued, the process may be completed in applications in less than 30 days. There is no fee
as little as 30 days. If an environmental impact for this pernut. ~
statement (EIS) is required, the process may take The 45-day requirement may be suspended
a year or more. The lead agency may establish under certain conditions for Forest Practice Appli- '
filing fees and may charge the applicant for prepa- cations (FPAs), or Section 10 and Section 404
ration of an envuonmental document. public notices circulated by the Corps. The latter
SEPA contains provisions for emergency ex- two permits also serve as official applicarions for ~
emptions. Projects are exempt from SEPA if they HPAs. When FPAs serve as HPA applications,
"must be undertaken immediately...to avoid an more mformation regardmg mstream modifica-
imminent threat to public health or safety, to tions is usually required before an approval can be ~
prevent an imminent danger to public or private issued. Also, the 45-day requirement can be sus-
property, or to prevent an imminent threat of pended by WDF/WDW if additional information
serious environmental degradation." is reyuested from the applicant. ~
For repair of streambank and other damage
caused by flood events, Engrossed Substitute Sen-
5.6 STATE PERMITS ate Bill (ESSB) 5411, commonly called the 1991
Flood Bill, requires a coordination meeting be- ~
The following section describes state permit tween the applicant and appropriate state, local, or
requirements. For more detailed information, county permitting or authorizing agencies within ~
please refer to Commonly Required Environmen- 15 days of receipt of a complete application.
tal Permits for Washingtvn State (Wash. Dept. Denial or approval of the project occurs within 30
Ecology 1990). days of receipt of a complete application. '
The Hydraulic Code states that in case of
emergency, verbal approval shall be granted by
' WDW or WDF immediately upon request for '
5-8 Permits and Policies '
' . ~
emergency work to repairexisting structures, move 5.6.3 401 WATER QUAUTY
obstructions, restore banks, or protect pmperty CERTIFICATION (WQC)
~ that is subject to immediate danger by weather,
Similar to the CZM Certification, the 401
flow, or other natural conditions or for drivmg water Quality Certification is provided by Ecol-
~ across a stream during an emergency. The agen- ogy for the federal agency. Under the Federal
cies provide a24-hour hofline for emergency needs Clean Water Act, Section 401 and Chapter 173-
(See Appendix B). Emergency HPAs allow neces-
sary work to proceed immediately, with project 225 WAC, this certification is required for a fed-
~
impacts and needed mitigation to be identified eral license or permit to conduct any activity that
after the emergency has passed. may result in any discharge into surface waters.
~ The proposed activity must comply with the dis-
charge requirements of federal law and meet the
5.6.2 COASTAL ZONE MANAGEMENT aquatic protection requirements of state law. No
~ (CZV1) CERTIFICATION OR fee is required for the certification. This permit is
DETERMINATION processed in conjunction with Corps Section 10
and 404 pernnit applications.
~ The CZM Deternunation which is required of
federal activities, decides if the activity is consis- 5.6.4 TEMPORARY WATER QUALITY
1 tent, to the maximum extent possible, with the MODIFICATION (WQM) PERMIT
Coastal Zone Management Program (CZMP)• The
CZM Certification which applies to private appli- If construction activities unavoidably violate
~ cants, certifies full consistency with the CZMP. state water quality criteria on a short term basis,
- The certification and determination were origi- the project will require a WQM from the Depart-
nally authorized under the 1972 U.S. Coastal Zone ment of Ecology. This r.:odification to water qual-
~ Management Act. The Act was reauthorized in ity standards may be required before Ecology can
1990 with amendments. issue a WQC. 'I7iere is no fee for a WQM.
The applicant provides Ecology with a de-
~ scription of the project and its coastal zone effects.
In addition, the project must be in compliance with 5.6.5 AQUATIC LAND USE
other regulatory requirements, including: AUTHORIZATION
, . the local Shorehne Master Program (i.e. it This authorization (WAC 332-30-122) may
must obtain a Shorelines Pernut if the activity be required if a proposed project requires transi-
t is located in a"shoreline of the state"; tory movement through navigable waters (e.g.,
• SEPA; mooring a barge). The applicant should contact
• the state water quality standards; and the State Depaitment of Natural Resources di-
~ • the state clean air requirements. rectly for a determination of navigable areas. Au-
thorization will not occur until all other permits
Ecology's Environmental Review Section pro- required for the project are issued. The time to
~ vides review and deternnination for projects being obtain the authorization may range between three
undertaken by the Corps. The Shorelands Program to six months, depending on the project location
reviews projects from all other federal agencies. and length of project time. If the activity is a
~ There is no fee for either the Determination or permanent project rather than a transitory activity,
Certification. DNR may requue a lease for use of the project
' area.
'
Pemnits and Pol'Kies 5-9
~ .
'
5.7 FEDERAL PERMITS These activities must commence or be under con-
tract to commence within two years of the date of ~
The two Federal permits most often required the destruction of or damage to the structure.
for bank stabilization projects are the Section 404 NWP 13 allows bank stabilization activities
permit for discharge of dredge and fill material, necessary for erosion prevention provided: ~
and the Section 10 permit for work in navigable
waters. Both of these permits are issued by the • no material is placed in excess of the
Corps. While individual permit applications may minimum needed for erosion protection; e
be required, work can be authorized by letters-of- • the bank stabilization activity is less than
permission, nationwide permits, or regional per- 500 feet in length;
mits. The following is a general summadon of the • the activity will not exceed an average of ~
Corps Regulatory Program and should not be one-half cubic yard per running foot placed
considered as definitive guidance. The Corps Regu- along the bank below the plane of the ~
latory Branch at the Seattle District Office should ordinary high water mark or high tide line;
be contacted for specific informadon. • no material is placed in any special aquatic
, site, including wetlands; ~
• no material is of the type or is placed in any
5.7.1 SECTION 404 PERMIT location or in any manner so as to impair
surface water flow into or out of any wetland ~
The purpose of this permit, which is required areas;
under Section 404 of the Federal Clean Water Act, • no material is placed in a manner that will
is to restore and maintain the chemical, physical, be eroded by normal or expected high flows ~
and biological integrity of the nation's waters (properly anchored trees and treetops may through the control of discharges of dredged or fill be used in low energy areas); and
material. Activities requiring a Section 404 permit • the activity is part of a single and complete ~
include discharge of dredged material, fills, groins, project.
breakwaters, road fills, riprap and jetties. Many
other activities such as ditching, drainage and Under the CFRs, the Corps has discretionary
~
vegetation removal may also be regulated under authority to reyuire mitigation for any adverse
Section 404. impacts to streams, wetlands, or other water bod-
Letters of Permission (LOPs) are given for ies. ~
minor or routine work with minimum impacts. A NWP 26 allows filling up to one acre in
Nationwide Permits (NWPs) are those that have isolated wetlands or adjacent wetlands that are '
already been issued to the public at large. There are above the headwaters. A headwater is defined as a
forty types of NWPs. (The reader is referred to the stream with a mean annual flow of less than five
Code of Federal Regularions, Appendix A to Part cubic feet per second. For activities affecting ~
330, for a complete listing.) Three nationwide greater than one acre of isolated or headwater
permits commonly related to bank stabilization wetlands, the Corps must be notified. Under the
projects are NWP 3- Maintenance, NWP 13 - NWP program notification procedures, the Corps ~
Bank Stabilization, and NWP 26 - Headwaters and contacts the appropriate resource agencies, such
Isolated Waters Discharges. The following infor- as the U.S. Environmental Protection Agency,
mation on these permits is taken from the Corps U.S. Fish and Wildlife Service, National Marine ~
Special Public Notice on Nationwide Permits- Fisheries Service, Ecology and other agencies.
Regional Conditions, State of Washington, dated After a 30-day review, the Corps decides whether
February 11, 1992. the NWP applies or an individual permit is re- ~
The NWP 3 authorizes the repair, rehabilita- quired.
tion, or replacement of those structures destroyed
by storms, floods, fire or other discrete events. ~
540 Permits and Policies ~
' .
Under the NWP 26, if the fill or area of adverse permits are currendy $10 for non-commercial
.
~ modification is: activity and $100 for commercial activity
• one acre or less, no notification is required
~ providing that the project complies with the 5.8 CONFLICTS IN
regional or national conditions of the REGUTATORY REQUIREMENTS
Nationwide permits. ~ • between one to 2 acres of fill. or adverse Conflicts can arise when two or more agencies
modification, notification is required by the involved with a proposed project have opposing
Corps. . regulatory requirements. Conflicts occur when
~ • greater than two acres, an individual permit there are differences in program goals or when
is required. contradictory design requirements are linked to
project funding. For example, the goal of protect-
~ Fills of any size in wetlands below the headwa- ing environmentally sensitive areas may not, in
ters, (i.e. waters whose mean annual flow equals or some cases, be compatible with providing public
exceeds five cubic feet per second) would require access. Similarly, projects funded by federal assis-
~ Individual permits. tance programs must use design criteria that, in
Routine processing rime for a NWPs is about some cases, conflict with local or state regulatory
30 days. An individual pernut may take six months requirements. The designer should be awaze of
~ or more. The fees for these permits are $10 for a these situations and how they can affect the final
non-commercial activity and $100 for a commer- design or funding a bank stabilization project.
~ cial activity.
5.8.1 CONTRADICTORY PROGRAM
~ 5.7.2 SEC?ION 10 PERMIT GOALS
This permit, which is authorized under Sec-
~ tion 10 of the U.S. Rivers and Harbors Act, is Intergovernmental Agreements
required for any structures or work in navigable
waters of the U.S. Examples of projects requiring Sometimes, conflict between two agencies or
~ Section 10 permits include utility lines, marinas, governments is resolved by intergovernmental
piers, wharves, floats, intake pipes, outfall pipes, agreements. These agreements or adjudications
pilings, bulkheads, boat ramps, dredging, dol- may result in specific requirements for proposed
phins, and fills. Navigable waters are those waters projects or maintenance practices. One example is
of the U.S. subject to the ebb and flow of the tide a 1985 agreement between the Puyallup Tribe of
shoreward of the mean high water mark and/or Iridians and Pierce County for vegetation manage-
~ which are presently used, or have been used in the ment in a portion of the Puyallup River drainage
past, or may be susceptible to use to transport basin. The agreement was the result of a dispute
interstate or foreign commerce, and their adjacent over the protection of fish and wildlife resources
~ wetlands. The purpose of these pernuts is to'pro- versus the removal of riparian vegetation for flood
tect the integrity of navigation channels and the control purposes. The agreement, named the
quality of waters of the U.S. (i.e., wetlands to the Puyallup River Vegetation Management Program,
~ territorial seas). provides standards for the management of riparian
These permits are issued by the U.S. Army vegetation. The document recognizes that scien-
~ Corps of Engineers District offices. Processing for tific approaches concerning vegetation manage-
a standard permit may be six months or longer. ment are evolving and therefore allows future
Letters of permission (LOPs) and nationwide per- modification of the guidelines to incorporate nec-
~ mits (NWPs) usually take 30 days. Fees for these essary management changes.
Permits and Policies 5-1 1
~
'
When a river is a jurisdicrional boundary be- and wildlife habitat. To be eligible for federal
tween counties, a Joint County F7ood Control funding, these same maintenance projects must '
Agreement can be used to cooperatively imple- meet the Corps and Federal Emergency Manage-
ment river projects that effect both jurisdictions. ment Agency criteria to remove or limit the size of
This type of agreement, used to form an Inter- vegetative growth. Often, this places the local ~
county River Improvement District (ICRID), cur- agency in the difficult position of choosing be-
rently exists between King and Pierce counties for tween abiding by state provisions to obtain the
the White River. permit or foregoing federal assistance needed to ~
implement the project.
The Corps, WDF and Ecology are currently
Intra-agency Programs developing a memorandum of understanding ~
(MOU) to clarify areas of concern involving re-
As discussed earlier, the King County SAO source management and flood control. This MOU ~
applies to all of the streams and rivers that are will develop new standards for vegetation on levees.
designated as shorelines of the state under the The directive to develop this MOU is provided by
King County Shoreline Master Program. These the 1991 Flood Bill (FSSB 5411) Secdon 19. This ~
two County reguiations have different goals that legislation seeks to allow eligibility for federal
may result in conflicting requirements. For ex- funding while adhering to the state HPA require-
ample, the Shoreline Management Program ad- ments. ~
dresses physical and visual access to shorelines. Examples of federal funding opportunities for
Conversely, the SAO seeks to protect the same construction or repair of flood control projects are
sensitive areas from significant impacts caused by described below. ~
activities such as recreation or view clearing along
shorelines.
The SAO also seeks to protect streams and U.S. Public Law 84-99 ~
floodplains from adverse environmental impacts,
but also to "meet the requirements of the National Rehabilitation assistance of non-federally con-
Flood Insurance Program [NFIP] and maintain structed flood control projects is provided under ~
King County as an eligible community for federal Public Law 84-99. For facilities eligible for PL 84-
flood insurance benefits." Specific requirements 99 funding, the local sponsor is responsible for 20
of the NFIP and the related Corps standards for percent of the cost of repair. This percentage may ~
flood protection may not always be compatible be in the form of funding, materials, equipment, or
with regulations for natural resource protection. services. The local sponsor is also entirely respon-
' sible for acquiring the necessary land rights and
' performing subsequent maintenance in accordance
5.8.2 DESIGN CRITERIA RELATED TO with Corps standards.
PUBLIC FUNDING AND The Corps performs an evaluation of the exist- ,
ASSISTANCE PROGRAMS ing facilides using prescribed criteria. This evalu-
ation documents the condition of the facility prior ~
Many local agencies rely on public assistance to a flood event. Based on the evaluation, the
programs for repairing flood control facilities. facility will be judged acceptable, minimally ac-
Implementation of state permit provisions to pro- ceptable, or unacceptable for rehabilitation assis- ~
tect fish and wildlife resources may not be eligible tance. Results of the evaluation are reported to the
for federal reimbursement. For example, Corps local agency responsible for maintenance of the
standards for flood control protection often con- facility. The local agency is given the opportunity ~
flict with state HPA requirements. A typical HPA to perform any necessary maintenance on the
condition for placing rock to maintain existing "minimally acceptable" and "unacceptable" fa-
levees is to re-establish bank vegetation for fish ~
5-12 Permits and Policies ~
~ .
cilities in order to upgrade their evaluati on to under $35,000. Projects can uaiso be split into
"acceptable" "improved" or "alternate" projects. Improved
~ The rating guide used to conduct evaluations projects include not only restoring the pre-disaster
includes inspection items relating to maintenance function of the damaged facility but also improv-
of vegetation on the facility. The guide specifi- ing the facility's flood protection capabilities.
~ callY evaluates "unwanted levee growth," refer- Improved projects receive federal funding up to
ring to allowable tree diameters and brush cover. the approved estimate of eligible costs. If the loc
~ For an "acceptable" rating, no large brush or trees agency determines that restoring the facility will
can exist in the levee section, and grass cover must not benefit the public welfare, the funds autho-
be well maintained. A"minimally acceptable" rized for that repair can be applied to an alternate
~ rating is given if trees of 2-inch diameter or smaller project. Alternate projects receive 90 percent of
andbrush cover are present that, in the evaluator's the federal share of the funding originally autho-
opinion, do not threaten the levee integrity. The rized for the repairs. These funds may be used to
~ facility is deemed "unacceptable" if trees, weeds repair or expand other facilities, construct new
and brush exist to an extent that they impair the facilities, or to fund hazard mitigation measures
evaluator's observation of the underlying levee. that reduce the risk of future damages either at the
~ The guide also includes criteria to evaluate the damage. site or elsewhere. Revegetation for fish
level of protection offered by the facility. An and wildlife habitat, which is often a condition of
"acceptable" levee will contain a flood greater the HPA approval, is a project component that has
~ than a 10-year event with three feet of freeboard. been considered ineligible for funding under PL
A levee is "minimally acceptable" if it can contain 93-288.
~ a five- to 10-year flow with one to three feet of
freeboard. An "unacceptable" rating results for
levees lacking five-year protection with at least Section 205 of the Fed-ral Flood Control Act
~ one foot of freeboard, orthat are less than three feet of 1948
in height. For the rating guide criteria and a com-
plete explanation of the PL 84-99 guidelines, the The Corps Section 205 program funds the
~ reader is referred to the Corps documentation (ER construction of new projects and the rehabilitation 500-1-1). of existing facilities. Under this Section, the local
jurisdiction must provide a portion of the funding
~ and participate as the "local sponsor" in the 205
U.S. Public Law 93-288 process. A Corps funded reconnaissance study is
followed by a detailed feasibility study in which
~ This legislation provides fundingby the FEMA costs are equally shared by the Corps and the local
for the repair of flood control facilities that are sponsor. Once the feasibility study is approved by
damaged in a presidentially declared disaster. As the CoW ~h dat ~~imum of Sc percenttifederal
' a reyuirement of the Stafford Act, the Public begm
Assistance Project Administration provides finan- funding.
cial assistance for repair work identified on Dam- Innovative projects that differ from traditional
~ age Survey Reports (DSRs). DSRs are prepared Corps designs can require additional reviews and
by an inspection team representing FEMA, the approvals. Conflicts between local and federal
state, and the local agency responsible for mainte- design standards must be reconciled in the 205
~ nance of the damaged facility. DSRs are usually process. Until these standards are agreed upon,
those using vegetative
completed immediately after the disaster and i k minnovative ethods, mayjbe delayed.
~ clude a scope of work and estimated cost of wo
eligible under PL 93-288 requirements.
Projects are split by cost and category. "Large"
` projects are over $35,000 and "small" projects are
5-13
~ Pernnits and Policies
~
National Flood Insurance Program (NFIP) time, careful attention must be given to the re-
quirements of existing regulations. Creative de- ~
The NFIP was established by the National sign approaches will be essential to construct and .
F1ood Insurance Act of 1968 to provide flood maintain stabilization projects that conform to
insurance protection to property owners in flood- applicable regulatory requirements. ~
prone areas. Several floodplain management re-
quirements must be met for a community, such as ~
a county or city, to qualify for federal flood insur- .
ance. These criteria are specified in the Code of
Federal Regulations (CFRs) for three types of
designated hazard areas: flood-prone, mudslide, ~
and flood-related erosion-prone areas.
For flood-prone areas, a participating commu= ~
nity must "prohibit encroachments, including fill...
within the adopted regulatory floodway that would
result in any increase in flood levels within the
community during the occurrence of the base ~
flood discharge." The base flood discharge is
defined as the 100-year flow event. FEMA, how- ~
ever, also requires that a levee have three feet of
freeboard for area to be considered protected from
the 100-year flood. Most existing freeboard-defi- ~
cient levees lying within designated floodways do
not fully contain the base flood. Establishment or
improvement of the levee freeboard may therefore
~
require placing fill in the designated floodway,
potentially increasing base flood water surface
elevations. For the local community to remain ~
eligible for federal insurance, it must prohibit such
an action.
A further complication exists if a levee free- ~
board improvement project is developed under
Section 205. Although the freeboard is required by
the NFIP, the Corps will not provide funding for ~
that portion of the project related to constructing •
the additional freeboard. Federal agencies are un-
der d'uectives, however, to resolve this discrep- '
ancy. As the above discussion illustrates, many con- ~
tradictory regulations currently exist. In some
cases, this contradiction can be addressed by de-
veloping projects designed to meet multiple ob- ~
jectives of federal and state regulatory and funding .
programs. In other cases, interagency differences
need reconciliation. As guidelines such as this ~
document are implemented and gain support
through proven environmental and economic ben-
efits, existing regulations may change. Until such ~
5-14 Permits and Policies ~
~ .
RECOMMENDED SOURCES FOR ~ ADDITIONAL INFORMATION
~
Washington State Department of Ecology. 1990.
Commonly Required Environmental ~ Permits For Washington State. Rpt. 90-29.
Olympia, Wash.
~ Washington State Department of Ecology. 1984.
State Environmental Policy Act Rules.
~ Chapter 197-11, Washington
Administrative Code. Olympia, Wash.
~ Seattle Audubon Society. 1991. A Citizen's
Guide to SEPA: How to Participate in the
Process. Seattle, Wash.
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Permits and Policies 5-15
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CHAPTER 6
~
ROIE AND USE OF VEGETATION
As discussed in Chapter 2, riparian vegetation • Root Reinforcement. Roots mechanically
~
plays an important role in the riverine environ- reinforce a soil by transfer of shear stresses
~ ment. This chapier focuses on the incorporation of in the soil to tensile resistance in the roots.
vegetation in bank stabilization projects. While • Soit Moisture Modification.
vegetation can introduce a cost-effective, self- Evapotranspiration and interception in the
~ maintaining mechanism for improving bank sta- foliage limit buildup of soil moisture stress.
bility, the species used should be selected to meet • Buttressing and Arching. Anchored and
the specific conditions of each site. This chapter embedded stems can act as buttress piles or
~ introduces some factors influencing species selec- arch abutments in a slope, counteracting
tion and provides guidelines for selecting vegeta- shear stresses.
tion most likely to succeedintheseryPesofprojects. • Surcharge. The weight of vegetation on a
~ bank exerts both a downslope (destabilizing)
stress and a stress component perpendicular
6.1 EFFECT OF VEGETATION ON to the bank whichtends to increase resistance
BANK STABILITY to sliding.
~
Windthrowing. Destabi lizing influence
•
~
Vegetation offers the best long-term protec- from tuming moments exerted on a bank
~cause of strong winds blowing through
tion against surficial erosion on slopes and pro- ~s, i.e., the toppling of trees and upheaval
vides some degree of protection against shaliow and associated soil.
~ mass-movement. Vegetation prevents surficial of the root mass
erosion by (adapted from Gray and Leiser 1982): The first three effects--rootreinforcement, soil
moisture depletion, and buttressing--enhance bank
• Interception. Fohage and plant detritus stabilitY. The fourth, surcharge, may have either a
~
absorb rainfall energy and prevent soil beneficial or adverse impact depending on soil or
~ compaction from raindrops. bank conditions. The last, windthrowing, maY
• Restraint. Root systems physically bind or negatively affect bank stability. In addidon to
restrain soil particles while the above- Gray and Leiser, Coppin and Richards (1990)
ground detritus filters sediment out of runoff. provide a thorough discussion of these effects.
• Retardarion. Plant detritus increases surface Vegetation adds stability to hillslopes by pro-
roughness and slow velocity of runoff. viding cohesion via the root systems and by reduc-
~ • Infiltration. Roots and plant detritus help ing soil water content through transpiration. Low
maintain soil porosity and permeability. clay content, non-plastic, granular soils are more
• Transpiration. Depletion of soil moisture susceptible to rapid mass soil movements (espe-
~ by plants delays onset of saturation and cially debris avalanches and flows) than more
runoff. cohesive soils, because shear strength is deter-
mined primarily by soil particle interlocking. Root
~ Vegetation, primarily woody plants, also helps systems of vegetation can stabilize shallow or
prevent mass-movement, particularly shallow slid- steep soils by anchoring the soil mass to fractures
' ing in banks. Possible ways woody vegetation in bedrock and tying hillslopes together across
affects banks include (Gray and Leiser 1982): zones of weakness (Sidle 1980; Ziemer 1981).
Woods (1938) studied the root sttucture of
~ many Pacific Northwest native plants. He found
6-1
~ Role and Use oF Vegela~tion
~
that the best plants for soil-binding include hazel, where soil strength would otherwise become crid- ,
vine maple, quaking aspen, willows, snowberry, cal. and kinnikinnik (all rated excellent), and A frequendy voiced concern about the use of
oceanspray, Pacific blackberry, black raspberry, plants in flood control and bank stabilization ~
and Oregon grape (all rated good). Sidle (1980) projects is that the roots will weakefl the structure.
reports that root strength tests show that coastal The main danger from prying or wedging would
Douglas fir roots are stronger than western hem- most likely arise from species with trunks or stem
lock roots, which are stronger that sitka spruce sizes that exceed the diameter or size of openings
roots. Many non-commercial trees and brush that in the face of levees, revetments, and other struc-
are often suppressed or killed by herbicides and tures. It is important, therefore, not to install veg- ~
slash burning have even stronger root systems. etation that will mature into large-diametertrees in
Ziemer (1981) reports that the live roots of shrubs the front openings of a structure such as a cribwall.
are twice as strong as coniferous roots of the same Similarly, anotherconcern is the susceptibility ~
size. Root biomass, however, is more important of mature trees to windthrow. Some species, such
than root size in improving stability. Smith (1976; as black cottonwood, red alder, or isolated, indi-
as cited in Gordon et a1.1992), for example, found vidual Douglas fir, have a potential to topple as ~
that a bank with a two-inch thick root mat of 16-18 they approach maturity. Plant form and size at
percent root volume afforded 20,000 dmes more maturity, longevity, and the location of larger
protection from erosion than a bank without veg- species selected for a project should be matched ,
etation. with the level of protection required at the site. ~
Often, surface erosion controls such as grass ~
6.2 LIMITATIONS OF VEGETATIVE seeding or hydro-mulching will work satisfacto-
. MEASURES rily at less cost than "engineered" solutions. In
some cases, a structural retaining system alone or
in combination with vegetation would be the more ~
Vegetative measures should not be viewed as appropriate and most effective solution. No matter
a panacea for all bank failures or soil erosion which approach is applied, the selected solution ~
problems. There will usually be some delay be- must address the mode and cause of failure.
tween the introduction of the vegetation and the
start of its active role. It may be weeks or months ~
for grasses and herbaceous vegetation, and several 6.3 PLANT S ELEC?ION
years for shrubs and trees, before the system is
fully effective. For vegetative streambank protection systems ~
If the banks are highly unstable, some initial to be successful, plants must grow well at the site.
safeguards against failure may be required. These Whether or not a plant species is appropriate at a
include biodegradable and synthetic geotextiles, particular site depends on several factors: purpose ~
cribwalls, or rock. These safeguards, which are of planting, soil moisture (permeability and drain-
described in the next chapter, may provide tempo- age), available sunlight, brush competition, poten-
rary protection until the vegetation becomes es- tial for animal damage, and elevation among oth- ~
tablished or may be incorporated as a long-term ers (Baumgartner et al. 1991).
component of the project.
There are also long-term effects (e.g., weath- ~
ering or changing moisture content) where bank 6.3.1 CHECKLIST FOR PLANT SELECTION
soils may increase or decrease in strength. In these ~
cases, the aim is to use appropriate plants in a The questions in Table 6.1 should be answered
complementary way. This could entail using rapid- as early in the project as possible. Some of these
growing plants to make up an early deficiency in questions will be answered by one person from a ~
soil strength, or slow-growing plants in situations particular discipl-ine; others will need to be an-
6.2 Role and Use oF Vegetation ~
swered by an interdisciplinary team. This team carefully reviewed for any projects stricdy limited
~ should consist of technical experts from the project to the use of native species. Table 6.3 provides
agency staff, staff from other agencies (1.tag.n,tDeanp ~ te additional
feed ng, f et~or ome plant species recom-
of Ecology or Fishenes), pnvate consu ,
~ or other individuals with appropriate expertise. mended for riparian areas-
The answers to these questions, used in con- None of the plant lists should be construed as
junction with the tables included in this chapter, definitive or absolute, but rather as suggested
~j will provide the basis for selecting the most appro- species, some of which are frequently overlooked
priate vegetation for a bank stabilization project. in traditional landscape architecture. Plant inven-
Common species suitable for the King County tory lists from nearby locations can also provide
~ area are listed in Table 6,2 along with information valuable information on native plants best suited
about size, habitat value, root form and depth, and to the project. There are no substitutes for on-site
propagation. Table 6.2 should be considered a analyses and site-specific recommendations: These
~ partial list of appropriate woody species for ripar- lists, however, are a starting point for gathering
ian planting. This table also includes some non- information and making preliminary, decisions
native but highly useful species. This list should be when few or no other data are available.
'
Tcble 6.1 A checklist for seleciing the most appropriate vegefction for a bank siabilizafion project.
What are ihe speciFic goals and objectives of the project? Re-establishment or enhancement oF eacisting plant
~ ~ communiy? Restoration of a previous plant community? If so, what time Frame (e.g., 1-,10-, 50-, 1 00-years ago)?
2 Whatare the geogrophic characteris6cs of the project site (eleva6on, slope aspect, and bpography)?
F31 What are the climatic characteristics of the project site (iypes, amount, and timing of precipirotion; length oF grawing
seoson; average temperafure; velxity and direction of prevailing winds; wailable light)? Will the light requiremenis
~ oF the plant assemblage (full light, partial shade, or shade rolerant) be met under the existing and/or anticipated
site conditions?
~ What soil types exist in the pr oject siie and adjacent areas? What ore Ihe speciFic characteris6cs of these soils
FA (permeabiliy; drainage; available waher capncity; fertiliy; lexture)?
~ What is the hydrology oF the project sile? Is the site periodically cavered with water? If so, how frequendr ond for
~ what length of time? Is the site covered by slanding water or Nawin9 w°ter2 IF Flawing water, what is the eshmated
~ depth and velociy? •
What is the condition oF the existing plant communiy? Is it a naturol plant assemblage? Has it been recendy alrered
or disturbed? If alhered or disturbed, ro what extent? What was the cause of the alteration (a single event versus
ongoing disturbbnce)?
Are there existing or planned access roads or pathways in and near the project site? What Form oF vegelation (herbs,
~ shrubs, trees) is appropriate For the iniended Function oF the bank (such as recreotion or mainlenance access, if any)?
■I Do site conditions require special design considerotions such as vegeiation height or shape, ype of root structure
~ For erosion control and bank srobili y(e.g., are veloci y contrd or windthrow a concern); soil ype and depih {e.g.,
~ are shollow soils or till present)?
6-3
~ Role and Use of Yegefiation '
~
Table 6.1 A checklist for selecting the most appropriate vegeiation for o bank siabilization project,
confinued. ~
~
Do presentor potential hazards to the integrily of the plantcommuniiy existon-site (e.g. grazing, recreational use,
~ dredging or maintenance activifies, encroachment by development activities, changes ro site hydrology and soil
moisiure, sediment deposition)? ~
~ O What will be the secondary (unction (aNer stabilization) of the project area: oesthefics; recreation (acFive or
passive); fish and wildlife hobiiat; sound or visual barrier; wofier qualiy prolection or treahneni? ~
Whot fish and wildliFe needs are or could be provided by ihe plant communiy (e.g., Food; shelter; nes6ng sifes; ~
migrotion corridors)? Is there an opportuniy No restore or enhance existing Fish and wildlife habilat (e.g., shading
for conMd of water iemperatures)?
What plant communities are reasonable and procticol given the real constraints of Ihe project sit~e, budget, and ~
12 reg,lanory rey~ireme,n?
What is the availability and cost of the desired plant species? What densiy of cover is desired, and in what 6me ~
frame? Haw much of the plant insrollation can be lost (e.g., mortaliy or vandals) and sfill meet projectgoals? What
is the budget For plant materials? ~
❑ What are the short- and long-ierm maintenance requirements oF fhe project siDe (disease and pest control; fire
14 control; weed/compefi6ve species conhrol; irrigotion; Frequenry oF inawing or brushing)?
Will the recommended vegetr~6on require special site prepara6on or equipment for inst~allation (e.g. control of
15 invasive species wch as reed canary grass; tree spades for larger sNock)? ~
Willtheprexribedvegeta6onrequiresupplemenlalirrigation,fertilization,orFencingtobecomeeslablished? Are
F161 these measures ovailable? ~
Givenlocalclima6candhydrdogiccondifionsandsiteconstrainh,whenisthebest6meoFyear{orplan6ng? Does ~
~ 7 planting need ro be staged over time (weeks, months, or years)? If there is no choice in planting fimes, what is
the best form of plant mafiericl ro use (live stakes, rooted cuttings, nursery stock).
F181 What are the skills of the planting crew? WII training be required? How large a crew is availoble? Haw large ~
i s t h e a r e a to b e p l a n t e d/ h o w l o n g w i l l i t to k e w i t h t h e w o i l a b l e c r e w? A r e a d e q u a t e p l a n t s t o r a g e F a c i l i 6 e s
available if maierial ccnnot be planied in one day? ~
~
~
6-4 Role and Use of vegeiation ~
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~
Table 6.3 WiIdliFe use oF selecied species. (From Hanley 1984, Washington Deparhnent of Wildlife [no
daie], Snohomish County 1990.) ~
COMMON NAME BOTANICAL NAME VALUE ~
maple Acer spp. moderate
alder Alnus spp. moderote ~
serviceberry Amelanchier alnifolia moderate
bearberry Arctostaphylos spp. moderate
Oregon grape Berberis nervosa moderate
paper birch Betula papyrifera moderate f
red-osier dogwood Cornus stolonifera high
hazelnut Corylus cornuta high ~
salal Gaultheria shallon moderate
oceanspray Holodiscus discolor *
trumpet honeysuckle Lonicera cilioso moderate
black twinberry Lonicera involucrata moderate ~
crabapple Malus fusca moderate
Indian plum Oemleria cerasiformis moderate
mock oran e Philadelphus lewisii *
Pacific nineark Physocarpus capitatus
Sitka spruce Piceo sitchensis moderate
lodgepole pine Pinus contorta high ~
western white pine Pinus monticola high
black cottonwood Populus balsamifera high
quaking aspen Populus tremuloides low
bitter cherry Prunus emarginata high ~
chokecherry Prunus virginiana high
Douglas fir Pseudotsuga menziesii moderate
ferns Pterophyta low ~
cascara Rhamnus purshiana moderate
currant Ribes spp. moderate
rose Rosa spp. moderote ~
salmonberry Rubus spectabilis high
blackberry Rubus spp. high
thimbleberry Rubus parviflorus high ~
willow Salix spp. high
elderberry Sambucus spp. high
Sitka mountain ash Sorbus sitchensis high ~
hardhock Spiroea spp. moderate
snowberry Symphoricorpos albus moderate
creeping snowberry Symphoricarpos mollis moderate ~
western red cedar Thuja plicata moderote
western hemlock , Tsuga heterophylla moderate
mountain hemlock Tsuga mertensiana moderate ~
huckleberry Vaccinium spp. moderate
highbush cranberry Viburnum opulus moderate
~
~ Not all species were rated for value, only noted that they were of value. Values include nesting, resting
and feding for birds, mammals, game, and other animals. ~
6' 10 Role and Use of Vegetation
6.3.2 PLANT COMMUNITIfS readily available from nurseries, they can be found
~ in nurseries specializing in native plants. If ad-
Schiechtl (1980) says that the use of unsuitable equate lead time is available, many nurseries will
plant species has been a major reason for failure in grow plants, under contract agreements, at lower
~ vegetative bank stabilization systems. Only plants costs than they can be obtained atherwise. As
from sites with ecological conditions similar to the more nurseries are now offering native species,
project site should be used. Locally obtained plants the cost of native species should become compa-
~ are generally better adapted than plants obtained rable to more traditional non-native plants.
from distance sources. Identification of the local A few woody plants are adapted to frequent or
plant communities is therefore the first step in prolonged flooding or to poorly drained soils (see
~ planning large-scale bank stabilization projects. Whitlow and Harris 1979 for information about
Ecologists recognize specific plant communi- flood tolerance). Most woody vegetation, how-
ties or associations based on dominant tree, shrub, ever, grows better with free drainage and usually
~ and forb species. In King County and lower Puget does not tolerate continuous waterlogged soil con-
Sound, the plant communities are typically mesic ditions. Sites with poorly drained soils may re
communities (i.e., those found in moderate mois- quire special treatment such as adding soil amend-
~ ture conditions) dominated by conifers. ments.
Year-round soil moisture is a major factor in Plants that grow in riparian and wetland areas
~ defining what species and therefore what commu- are often well suited to bank stabilization projects.
nities will characterize a given area. Therefore, the Riparian vegetation is similar to wedand vegeta-
process of compiling recommended species lists tion and yet distinct. Wedand vegetation is de-
~ for planting along streams and rivers depends on fined as plant species that are found in wetlands
soil moisture conditions that are expected to be with some range of frequency (Reed 1988). Called
present in the area. This information can be ob- hydrophytes ("water loving"), these plants often
tained from a variety of sources. The U.S. Soil have physical or physiological adaptations that
Conservation Service soil survey, for example, enable them to compete more effectively in satu-
contains information on drainage, permeability, rated, oxygen-poor soils. In contrast, riparian veg-
~ depth to water table, and other characteristics of etation is vegetation growing in close proximity to
local soil series. The U.S. Fish and Wildlife Ser- streams or rivers to influence or be influenced by
vice National Wetlands Inventory maps provide those waterbodies. These plants may or may not be
~ information on depth, duradon, and frequency of hydrophytic. It is important to realize that many
soil saturation and/or inundation. Consideration of species selected for wetland projects may not be
this information is important in selecting appropri- appropriate for riparian projects, due to different
~ ate plant species for a given site. Although not a tolerance levels of drought, inundation, flooding,
substitute for information collected from on-site or moving water. Simultaneously, there are many
evaluations, these sources provide initial baseline species commonly used in wetlands with very
~ data. wide tolerance ranges, and many of these are
Plant species should be selected for particular highly suited to riparian habitats as well. In ripar-
areas based on their moisture requirements and ian planting schemes, some plants with the ability
~ tolerance levels. Table 6.4 1ists five generalized to withstand extended.periods of drought, espe-
plant associations (very droughty, droughty, mod- cially for areas high on the bank, will likely be
~ erate, wet and very wet) for revegetating riparian needed.
corridors. These associations are defined by match- Another goal is to select species that can com-
ing local-native species with anticipated soil mois- pete with and eventually shade out reed canary
~ ture conditions. In Table 6.4, plants that require grass or other undesirable species. Prior to plant-
greater or lesser wet soil conditions were placed in ing, preliminary mechanical control (tilling or
groups specified for wetter or drier sites, respec- cutting) should be used to reduce initial competi-
~ tively. While some plants in this list are not always tion and allow easier placement and planting of
Role and Use of Vegefiation 6'1>
~
~
species. It will also be necessaryto select amidstory from trampling and other disturbances. Species in
of small trees and shrubs that are shade tolerant. Table 6.4 marked with a dagger ( f) have rapid ~
Certain species are well suited for planting in regrowth and high tolerance to disturbances such
areas which may be designated as access corridors as pruning to ground level and disruprion by heavy ~
or where maintenance activities occur. These ar- equipmenf.
eas require plants commanities that recover well
~
Table 6.4 Species recommended for proposed plant associations for revegetation of riparian corridors.
~
Indic. Max. Elev. Plant Associations
Common Name Scientific Name . Stat. Ht. Range A B C D E
* * * ~
vine maple Acer circinatum FACUt 25 I-m
big-leaf maple Acer macrophyllum FACUt 100 I * * *
serviceberry Amelanchier alnifolia FACU 30 I-h * * * ~
tal) Oregon grape Berberis aquifolium UPL 7 I- * *
(ow Oregon grape Berberis nervosa UPIt 2 I-m * *
paper birch Betula papyrifera FACU 65 * * * ~
Pacific dogwood • Cornus nuttallii FACU 65 I- * * *
salal Gaultheria shallon UPIt 7 I-m * *
ocean spray Holodiscus discolor UPLt 10 I- * * ~
trumpet honeysuckle lonicera ciliosa UPL 3 I- * *
mock azalea Menziesia ferruginea FACU 7 m- * * *
Indian plum Oemleria cerasiformis UPIt 15 I- * * ~
Oregon boxwood Pachystima myrsinites UPL 3 m- * *
choke cherry Prunus virginiana FACU 20 I- * * *
bitter cherry Prunus emarginota FACU 50 I- * *
Douglas fir Pseudotsuga menziesii UPL 300 I-h * *
red-flowering currant Ribes sanguineum UPIt 7 I- * *
clustered rose Rosa pisocarpa FACUt * * * ~
thimbleberry Rubus parviNorus FACUf 10 I-h * * *
black raspberry Rubus leucodermis UPIt 10 I- * *
red elderberry Sambucus racemosa FACUt 20 I-m * * * ~
Cascade mountain ash Sorbus scopulina UPL 20 * * ~
creeping snowberry Symphoricarpos mollis UPIt 1.5 I-m * *
snowberry Symphoricarpos albus FACUt 7 I-m * * * ~
Pacific yew Taxus brevifolia FACU ' 80 I- * * *
western hemlock Tsuga heterophylla FACU 200 I-m * * *
red huckleberry Vaccinium parvifolium UPl 13 I- * *
oval-leaf huckleberry Vaccinium ovalifolium UPL 3 * * ~
Oregon viburnum Viburnum ellipticum UPL * *
red alder Alnus rubra FACt 80 !-m * * ~
hazelnut Corylus cornufia FACf 15 I * * *
black hawthorn Crataegus douglasn FACi 20 * * *
black twinberry Lonicera involucrata FACt 10 I- * * *
western crabapple Malus fusca FACt 20 I- * * * ~
mock orange Philadelphus lewisii FAC 10 I- * * *
Pacific ninebark Physocarpus capitatus FACt 20 I-m * * *
~
Role and Use oF Vegetation 6-12 ~
~ . Table 6.4 Species r+ecommended for proposed plant associations for revegeioiion aF riPcrian coRidort,
~ confinued.
Indic. Max. Elev. Plant Associations
Common Name Scientific Name Stat. Ht. Range A B C D E
~
* * *
Sitka spruce Picea sitchensis FAC 230 I * * *
~ black cottonwood Populus balsamifera FACt, 120 I-m * * *
cascara Rhamnus purshiana FAC 30 I- * * *
prickly currant Ribes lacustre FACt 7 I-h *
Nootka rose Rosa nutkana fACt 7
~ * * *
salmonberry Rubus spectabilis FACt 15 I-m * * *
Scouler willow Salix scouleriana FACt 40 * * *
~ western red cedar Thuja plicata FAC 230 I- * * *
wild guelder rose Viburnum opulus FAC 10 * * *
red-0sier dogwood Cornus stolonifera FACWt 20 I- * * *
Oregon ash Fraxinus (atifolia FACW 65 I- * * *
~ Pacific willow Salix (asiandra FACW+ 40 I- * * *
Hooker's willow Salix hookeriana FACWt 40 * * *
Geyer willow Salix geyeriana FACWt 15 I-h * * *
~ Douglas spirea Spiraea douglasii FACWt 7 1=h * * *
highbush cranberry Viburnum edule FACW * *
bog rosemary Andromeda polifolia OBL 2.5 * *
bog birch Betula glandulosa OBL 15 I * *
alpine laurel . Kalmia microphylla OBL 2 m-h * *
bog labrador-tea Ledum groenlandicum OBL * *
~ sweetgale Myrica gale OBL 7 * *
under-green willow Salix commutata pgLt g * *
heart-leaf willow Salix rigida OBIf * *
~ bog willow Salix pedicellaris OBLt 3 . * *
diamond-leaf willow Salix phylicifolia pgL' 12 * *
wild cranberry Vaccinium oxycoccos OBL
~
Indic. Sbat = plant indicator status (UPL, FAC, etc) from USFWS (Reed 19881, or odapted from Hitchcock and Cronquist
~ (1973). Species marked (t) indicate trees andshrubs tolerant of severe pruning: these eitherstump sprout readilyorsucker
from roots.
~ UPL Obli9ate upland: occurring almost exclusively in non-wedand environments.
FACU Facultative upland: occurring primarily in non-wetland environments, but also frequendy in cerroin fypes of
~ wedands.
FAC Facultative: occurring with approximately equal frequencies in wetlands ond non-wetlands.
~
FACW Facultative wetland: occurring primarily in wetlandenvironments, but also frequently in non-wedands.
~
OBL Obligafe wetland: occurring almost exclusively in wedand environments.
~
Role and use of vegerotion 6-13
~
Table 6.4 Species recommended for proposed plant associations for revegeiation of riparian corridors, ~
oonfinued. .
Max. Ht. - the approximate height (feet) to which plants will grow under natural conditions with sufficient time. ~
Mature height, or the size at which plants begin to Hower and produce seeds, is substarniolly less in many species.
Elev. Range- the elevations where the s ies commonl occurs. 1=1ow, sea level to 2500 feet, m=mi ~
p e c y d, 2500 t o
4500 feet, h=high, above 4500 fee►. All elevations are variable depending on microclimates.
~
Plant Associations - planting suggestions for different soil moisiure regimes based on soil information from the King
Counly soil survey (SCS 1973) and indicator status (Reed 1988). Nomenclature follows Flora of the Pacific ~
Northwes► (Hitchcock and Cronquist 1976) and National List of Plant Species that Occur in Wedands (Reed 1988).
Plant associations recommended for various soil moisture levels:
A. Very droughy soils: use UPL and FACU species. These conditions may be expecfed in porous or welN
drained (sandy) soils or high on the bank, especiall y on south or west facing banks wiih litile shade.
8. Droughy soils: use mosdy UPL and FACU species; FAC species may be used occasionally if.site conditions ~
are somewhat moist. These soils occur in areas similar to very drough►y soil, but where moisture retention is
better (e.g. less sandy soils, shade, and north or east facing banks).
C. Moderate soils: use FACU, FAC, and FACW species. Most of King Caun►y has these soils. They are loamy ~
soils with some clay, on level areas to steep slopes. They may be shallow soiJs over hardpan, or areas
where seeps are common. Plant selection should consider microclimatic conditions including seeps, slope,
aspect, etc. Steeper slopes, for example, will be drier than level soils because of water run off. ~
D. Wet soils: use mostly FAC and FACW species; OBL species con be used in particularly wet areas as long
as the soil is no► compacted. In King Couny, most of these soils consist of nearly level silt loams. They retain ~
water rather than allowing it to run o(f aher roin, and are moist to wet for most or all of the year. Because
these areas have minimal slope and ypicaliy slow-moving streams, erosion is seldom o problem.
E. Very wet soils: use FACW ond OBL species. These soils may be found along meandering rivers and streams ~
with low banks. There is ypically a high water table that allows the development of organic soils (peats and
mucks). They are not well suited to large woody vegetation, as trees tend to blow over. Dense thickets of
shrubs and small trees are common. Because these areas have minimal slope and lypically slow-moving ~
streams, erosion is seldom a problem.
~
6.3.3 SOILS Sigruficant soil characteristics include drainage,
compaction, texture, structure, strength, nutrients,
A basic understanding of soil is essential for and pH. Texture and structure are important for ~
anyone designing or installing landscape plans, root penetration and soil moisture. While gravelly
regardless of whether the landscape is a formal and sandy soils drain freely and allow good root ~
garden or an ecological restoration project. While penetration, they are easily eroded and droughty.
soils are responsible for the poor performance of Plants selected for such sites should be species that
landscape plants more often than any other single grow well under these conditions. Soils with high ~
factor, they are often given little consideration clay content resist erosion and hold water well but
(Harris 1992). Landscape plants probably suffer may restrict root development. Finely textured
more from moisture-related problems (either too soils also are more prone to soil compaction than ~
much or too little) than from any other cause. are coarse or sandy soils. Compacted soils require
6- 14 Role and Use of Vegetation ~
~ . Y
additional preparation(discussed further in Chapter given area. Most, if not all, series occurring in
~ 7). Soil conditioners can be applied during King County are tcaversed by streams and rivers.
construction to modify physical soil conditions. Disturbed soils needing revegetation may be
Plants vary in their tolerances to pH condi- atypical of naturally occurring soil series. Such
~ tions. If soils are unusually acid or alkaline, it may soils lack the usual physical structure found in
be possible to select plants suitable for that condi- undisturbed soils, and drainage and permeability
tion. Most plants do well with soil pH between 6.5 may differ substantially from nearby areas• Dis-
~ and 8.3. Acid-loving plants grow well between pH turbed areas nonetheless have certain characteris-
4.0 and 6.5. tics, such as texture, water and air content, density,
The soils at each site, or every one hundred pH, and organic content, that influence plant per-
~ (100) feet on large sites, may be checked for formance and selection. A summary of the charac-
nutrients, pH, and toxins. Nutrient tests, however, teristics of King County soils is provided in Table
are of limited value for woody landscape plants, 6.5. Evaluation of soils on the project site, plus
~ especially trees (Harris 1992, citing other au- information presented in Tables 6.4 and 6.5, along
thors). Soil fertilizers and conditioners may be with professional judgment of horticulturists and
required for poor-quality soils to produce opti- ecologists, should be used together to identify
~ mum growth conditions for the species selected. plants suited to the soil moisture conditions at each
Soils may need to be treated to alter pH on sites project site. Thus, appropriate plants may be se-
with severe problems. If soils at a site contain lected from the plant association list (Table 6.4)
~ substances toxic to plants, the soils may have to be corresponding to the on-site soil type(s) (Table
removed and replaced. 6.5).
~ Soil samples should be taken of all fill materi-
als that are brought to the site prior to use if their
ability to support plants is quesrionable. Soils
~ from deep excavations, several feet below the
topsoil layer for example, may lack the nutrients.
or microorganisms necessary for plant growth.
~ Testing by an approved laboratory may include
analyses for a range of nutrients including nitro-
gen, phosphorous, and potassium, as well as pH.
~ The laboratory reports should also include recom-
mended fertilizer and lime amendments for woody
plant materials. Basic soil analyses typically cost
~ less than $30 per sample; tests for pesticides and
other contaminants have additional costs.
~ Soils in King County (more than 30 different
soil series) range in moisture content from very
poorly drained to excessively drained (SCS 1973).
~ The SCS specifies seven natural drainage classes
that are defined by the frequency and duration of
saturation or partial saturation that existed during
~ the development of the soil since the last glacia-
tion. The SCS soil survey for King County, which
mapped the soil types for much of the county
~ (excluding Seattle ancl the forest production zone
in the eastern half of the King County), is an
excellent source of information about what gen-
eral types of soils can be expected to occur in any .
Role and Use of Vegeiotion 6-15
~
Table 6.5 Moisiure conient, plant associctions, erosion pohential of King County sals, and percent of
mapped King County area covered by various soil fypes. (Adapted from SCS 1973.) ~
MOISTURE CONTENT PLANT SOIL SERIES EROSION POTENTIAL PERCENT OF
(DRAINAGE ASSaCIAl10N KING COUMY -
CLASS) AREA ~
very droughty A Neilbn slight to moderate 1.4 ~
(excessively Pilchuck moderate to severe
drained)
droughty (well B Beausite moderate to very severe 19.5 ~
and somewhat Edgewick slight
excessively Newberg slighr ~
droined) Nooksack slight
Oval) slight to severe
Puyallup slight ~ Ragnar moderate to severe
Salal slight
Everett slight to severe ~
Indianola slight to severe
Klaus slight
~
moderate C Alderwood slight to severe 58.9
(moderately Kitsap slight to severe ~
well drained) Si slight
Sultan slight
wet (poorly D Bellingham, Buckley, all have slight 11.6 and somewhat Norma, Oridia, Puget, erosion potenfia)
poorly drained) Renbn, Snohomish, ~
Woodinville, Briscott,
Earlmont, Sammamish
very wet (very E Orcas none 2.8
poorly drained, Seattle none to slight
organic) Shalcar none ~
Tukwila slight
Total 94.2 * ~
* The remaining area consists of either ) J soils so disturbed that they cannot be dassified os soil series or 2) such ~
small oreas that they could not be mapped individually at the survey scale.
~
6-16 Role and Use oE Vegeiction ~
6.3.4 MULCHES Mulches improve soil structure and, other than an
~ Control of surface erosion and maintenance of initial nitrogen deficit, reduce the need for fertil-
soil moisture levels can both be attained by using izers. Chamberlain (1986), describing plant in-
mulches. Mulching not only reduces future main- stallations in late summer, stated that "without the
~ tenance requirements, it also increases plant sur- (straw) mulch, it is doubtful that the plants couid
vival. Mulches may be inorganic or organic, with have survived without constant watering: "
~ or without erosion control seed mixtures. Selec- Mulches provide immediate protection from
tion of a particular mulch depends on site charac- surface erosion and help retain soil moisture es-
teristics, product availability, costs associated with sential for rooting. Lack of soil moisture, caused
acquisition and installation, effectiveness (Kay by evaporation from the surface from wind or sun,
1984), and the purpose of the mulch (Table 6.6). and surface erosion both contribute to planting
~
Most organic "mulches will require additional ni- and live staking failures. Many authors (USFS
~ trogen to compensate for the tie-up of nitrogen in 1989) describe the use and benefits of various
the decomposition process. Mulches may be used mulches for erosion control and vegetation estab-
to prevent establishment of competitive weeds on lishment.
~ new slope stabilization projects or to introduce Some mulches may be detrimental to estab-
selected species as surface cover or around plants. lished or establishing woody vegetation. If an
The use of mulches results in increased gernuna- organic mulch is used, especially wood chips or
~ tion of applied seed mixes (Sears and Mason sawdust, the decomposition process requires a
1973). Mulches also"increase soil moisture reten- large volume of nitrogen. This creates a nitrogen
don and decrease the need for frequent urigation. deficiency in the soil, which can be remedied by
~
Table 6.6 Benefits and limitaiions of various ypes of mukhes.
TYPE OF MULCH BENEFITS LIMITATIONS
chi wood reodily avaibble; aesthetically ^wY Pr~'1 establishment
~ accepted; inexpensive volunleer seedlings iF too deep;
• creates nihogen deficiF
~ rock uwally avaibble on-sile; can create blankeF Ihat
inexpens'rve inhibits plant growth
immediate co~r Fllowed by grosses maY need ro be anchored; may
straw or hay
From seecJs (unless specified aweed N), . contain undesirable species
(ree
very cost eFFectivc
hydroulic mukh grass-legume mixes bind and ^aY CO'"Pete `""t' `"'O°dY
and seed mixes improve soil; bw labor costs vegetation fior water and
nutrients during establishment
organic or inorganic duroble ro readiy "Y~' °r P~O~ rt1°~' ~
~~~I tc wildliFe; may haMe high
iabric or mats biodegradable depending on
type; effective on steep slopes labor and ma►erial costs
~ commercial can be nitrogen srobilized can be expensrve for large areas
~t and oF pmclictable quality;
improves soil quality
Role and Use of vegetation 6-17
~
RECOMMENDED SOURCES FOR ADDITIONAL INFORMATION
Bache, D.H. and I.A. MacAskill. 1984.
Vegetation in Civil and Landscape
Engineering. Granada Publishing Ltd.
London, England.
Bailey, L.H., E.Z. Bailey, and staff of the L.H.
Bailey Hortorium. 1976. Hortus third. ~
New York: Macmillan. ~
Coppin, N.J. and I.G. Richards. 1990. Use of
Vegetadon in Civil Engineering. London,
England. L ~
Gray, D.H. and A.T. Leiser. Biotechnical Slope
Protection and Erosion Control. Van
Nostrand Reinhold Company. New York.
. ~
Hairis, Richard W. 1992. Arboriculture:
Integrated Management af Landscape ~
~ Trees, Shrubs, and Vines. 2nd ed. Prentice
Hall.
Larson, F.E. and W.E. Guse. 198 1. Propagating ~
Deciduous and Evergreen Shrubs, Trees, '
and Vines with Stem Cuttings. Pacific
Northwest Extension Publication
PNW 152.
Marchant, C. and J. Sherlock. 1984. A Guide to
Selection and Propagation of Some Native
~
Woody Species for Land Rehabilitation in
British Columbia. B.C. Min. For. Research ~
Report RR84007-HQ. ;
£ {
Schiechtl, H. 1980. Bioengineering for Land
Reclamation and Conservation. University
'
of Alberta Press. Edmonton. '
~
Whitlow, T.H. and R. V. Harris. 1979. F1ood ~
Tolerance in Plants: A State-of-the-Art ~
~ Review. Tech. Rpt. E-79-2. U.S. Army ~
Corps of Engrs. Waterways Exp. Station, ~
Vicksburg, Miss. '
~
,
~
6-20 Role and Use of Vegebtion '
~
~
CHAPTER 7
~
DESIGN GUIDEIINES
~ While there are many effective means of a single design with an appropriate transition at
bank erosion control available, not all techniques their common boundary. It is also important that
~ work equally well in every situation. Many inef- the geometry and hydraulic characteristics of the
fective techniques are used as quick solutions to stream channel in all three perspectives (cross-
long-term problems. To choose the best solution, section, plan view, and profile) be fully examined
~ a match must be made between the objectives of and investigated. This understanding of the stream
the project, existing site conditions, possible tech- is essential to achieve a successful integration of
niques, and fish and wildlife habitat concerns. the project with the natural channel.
~ Only after the cause of the failure has been This chapter describes basic design consider-
clearly defined should a bank stabilization plan be ations and criteria for rock, vegetated, and inte-
prepared. Bank stabilization projects fall in two grated (i.e., vegetation, soil, and rock) methods for
~ broad categories: those that correct the problem bank stabilization. Also included in this chapter
and those that compensate for it. Even though the are suggested habitat components for these meth-
~ most effective way to stabilize a bank is to elimi- ods, and a brief discussion on preparing design
nate the cause of the instability, measures to com- drawings, plans, and specifications.
pensate for a problem are often used in addition to
~ or instead of correcting the fundamental cause. It
is vital to ensure that the proposed project solves or 7.1 STREAMBAN K ZON ES
helps solve the problem before proceeding with
~ the project. As discussed in Chapter 3, streambanks can be
As mentioned previously, because of the com- divided into three zones: the tce zone, bank zone,
plexity of most bank failures, integrated, interdis- and overbank areas (Figure 3.1 and Figure 7.1).
~ ciplinary, effective teamwork is required at all Fi9ure 7.1 qbank srobilization project with c rock
project stages. Knowledge of many aspects of tw key,
riverine environments is essential if bank stabili-
zation projects are to be successful. Again, it is
strongly recommended that a team approach be
used when developing or reviewing possible bank
~ stabilization projects. The nature of the project
will likely dictate the most suitable qualifications
or experience required of the team. At a minimum, ;
~ .
the team consisting of an engineer with experience
in river systems, an ecologist knowledgeable in fisheries and riparian ecology, and a soil scientist of-rwv
~ will generate the most successful projects. Some
projects may require the specialized skills of a R°d` 'k
geomorphologist, botanist, or lan dscape arc h i tec t.
~ Although the streambank zones above and
' . .4.'•:.:.:...'.;;'. I
below the ordinary high water mark are treated
. ' '.I.~ separately in these guidelines for organizational
~ reasons, it is important that the entire bank be exIsnNO ToE BArxc °VEReAW
CHMINELBED ~ ZONE ZONE ZONE
considered as a single entity. Toe protection and
~ vegetative components must be incorporated into $EanON
7- i
~ Design ~Guidelines
N ~
This section summarizes the characteristics of cause berms reduce effective bank height and
these three zones, focusing particulazly on the provide extra toe support for the upper bank. ~
design implications for each zone.
7.2. DESIGN OPTIONS AND CRITERIA ~
7.1.1 TOE ZONE FOR DIFFERENT METHODS
The toe zone, which is the area of bank below Bank stabilization methods can be categorized ~
the ordinary high water mark (OHWM), is usually into three fundamental types: rock, vegetative,
inundated and subject to toe erosion and undercut- and integrated. Rock methods are those that rely
ting of the bank. Because of the harsh conditions on riprap and/or large boulders to armor the tce
in this, woody vegetation generally does not grow and sometimes the bank, or redirect erosive flows.
here; as such, bank stabilization methods that rely Vegetative methods are those that use plants or ~
primarily on vegetation are not particularly effec- plant cuttings to stabilize the bank. Integrated
tive. Methods that are commonly used to stabilize methods are those that incorporate various materi-
this zone are rock toe keys, cribwalls, and large als (rock, timber, soil, and plants). In combination ~
woody debris. with these materials, integrated methods may also
include fabrics such as jute or coir mesh.
To help designers in selecting solutions appro- ~
7.1.2 BANK AND OVERBANK ZONES priate for each situation, the following discussion
provides basic descriptions of each method and
The bank zone, which is between the OHWM general selection criteria. Installation procedures, ~
and the top of the bank, is inundated during periods including relative quantities of material required
of moderate (i.e., up to bankfull) flows and ex- and construction techniques, are discussed in Chap-
posed to periodic erosive currents and debris move- ter 8.
~
ment. Woody and herbaceous vegetation grow
well here. All three bank stabilization methods
mentioned above (rock, vegetative, and integrated) 7.2.1 GENERAL DESIGN ~
may be used in this zone. CONSIDERATIONS
The overbank zone is the area landward of the
top of bank which is subjected to occasional inun- There are many factors to consider when se- ~
dation during flood flows. Important consider- lecting a design option. Among these factors are
ations in this zone, where riparian vegetation tran- the stream characteristics (cross-sectional dimen- ~
sitions into upland areas, are wildlife habitat and sions, flow depth, velocity [both magnitude and ,
access forproject construction and long-term main- d'uection] and slope of bed or bankline being
tenance. protected). Construction techniques and methods
Most stream channels have complex cross to minimize adverse impacts to the riparian envi-
secdons. Often there are one or more small chan- ronment should also be considered.
nels that concentrate flow during low flow periods Location of the Structure. Most King County
and a larger channel in which flows are confined levees and revetments were constructed along
most of the time. Low flow channels are often natural channel banks to convert as much of the
flanked by one or more sand or gravel bars that floodplain as possible for other uses. Recently, ~
may lack permanent vegetation. Active channels recogtizing the benefits of floodplain conveyance
are generally flanked by sedimentary berms or and storage, and the drawbacks inherent in en-
erosional scarps covered with perennial vegeta- croachment on the channel, this policy has changed. ~
tion. Compound, mulri-sloped banks tend to be (See discussion of King County Sensitive Area
more stable than simple, single-sloped banks be- Ordinance in Chapter 5). Cument practice, when-
ever possible, is to set back at least the upper bank ~
7.2 Design Guidelines
~
of any new facility from the main channel. The toe tion or easements. In these situations, a rock wall,
secdon can be built at the location of the existing live cribwall or vegetated geogrid could be used to
~ bank, with a bench constructed at the ordinary create a steeper slope.
high water line, and the upper bank set back. Design Flow. Because structure design is based
~ Figure 7.2 illustrates a setback levee with a veg- on flood velocities and depths, it is necessary to
etated bench. In time, vegetation planted on the select one or more design flows to analyze the
bench will extend out over the river to provide hydraulics of the reach and find the values of the
~ shade and cover along the stream margin for fish. necessary variables. A range of flows, up to and
Bank Sloping. Most methods of streambank including the 100-year event, should be examined
protection will require some bank regrading. Steep depending on the site characteristics, projeCt com-
~ or undercut banks may require regrading the slope plexity and its associated risks. Of particular inter-
to 211:1 V or flatter. Because of their unconsoli- est is the bankfull or overtopping event for the
dated nature, streambanks with sandy soils may structure in question; this event generates the
~ require slopes of 4H:1 V or flatter. The application greatest velocities and tractive forces.
of inethods that require extensive bank sloping Design Velocities. Local water velocities (i.e.,
may be limited by the close proximity of structures velocities at or near the area of erosion), not
~ (i.e., buildings, roads, utilities), loss of vegetation average channel velocities, should be used for
of significant size (i.e., large trees), land acquisi- design. Local velocities along the autside of bends,
~ Figure 7.2 Setback levee.
~
~ .
Existing
~ flood stage
~ Flood stage after
setback levee construction
~ -
~ • ~
~ ~
: .
' PROPOSED • ~ ~ EXISTING LEVEE %
SETBACK LEVEE TO BE REMOVED - = Flood stage reduction
k' 1'ti
. . • . . ;.<:~:..,..o:c,wn::x.+;.n;;a:.~:.;;i..:,ti;1►::,'t'{,?:?,`~•';`::~~:t;?c:~'c::, fi...~~.~x.~''.'~3,~.'~?'}°f,n,`~,•,.~~`,.4';.~z..,•'••~.','fi;
. . . . ':~iNSi:rti?•,W,.{{:titii::{h:iiti}ti;•w:::::.~::k-}vv,v,•};:+.•::::r:~w:•i;:wN:.:•v.•.•a.:::4.tiva:.4~C~.,..v.\;~~ $ .yh~..{•.~•.:v.
~ {..:4•~i`.;•.~:.~}i:v.:?;\.:v}:t:::n:i?.y....v:\ •.ti.; 4',is}~:{+..' `.~.\+•~.•4,
•:?::i ^ U'4: . }?;'.}';'•~v .'n . L:vi`v..... . .
~.v ~:,}.y:
. k+.
. . . . . ...yw:. ~ .:..v.
>•2.}•::.:
~:?Lf>:i:v :~':i}{
,4i::::,}
. . . i•i;~:..v;v •
. . ~ r
i?.v
. l. . v}:w. •.~::vr~''.
?y?\ tii)~:i~ ..n :
~
:}}~..v.
~ . .
. •
h~4.
•.v{, ~}v. S.C.^li•
, ' . ' '
• '•.4 i.: {
43'piiiiii0.
w:..~.v:.v.::~ .
~ i
. i'~'~} ~k ..U: • 4
ti •:i 'ii:`•'•';?.
i\i \v}r... . r,~i.. .
. J:.hy:?:ti~ :2
. L}}'i•'.$ :::+:ii; ~ ;~.i •ti• ; .
. •:}`,:;v}:::tii:i:}+•: ti..•,~•;•;:tii;:}ti. :ti.
':?'vk'y1:' ~ • v,.;,•';~'r:•••
y\n..~~ .P.1•
:::i}~'}:''$i:i ~.~v. +i•:~.}
. ' . . • • . . • .
. 4..
'"}•~:..x.. 1.,..,.Yx,L.: '•::~.ti.::>v~~},i•,~v~'•i `}}fi~:} ;ti
: ~':k;'•::}i~':v::{~}::i:~::ti;?':?;ti?ti:iti':}?'}>.:}:v:ti~L::;.•'{`,:i~r
. • . • . ; . ' ~ • .
. vr :~:.:v:.:.~•:: r.;;.;:.~:.~:iv.:v.: `.•::.~ii6`.:;:; .x~:.\',~tii;}.}v~.?:}..i':\14~:}:1t;~;~?::.; .
•
. . . :i~:ii'%:ti;. . '.'ii;;T~::ii~:i:.rk.•y~. . •\v:•.: ..vv;~.Tnt':. ~ ~
_ ~'~:.},..ti~ :.::':::':;~ti•i::•}i:ti~:~:~:~i:i'v<:>:;:.:::
. r.::: i.:: •
' : . . . : . . . . . . . ~ . •
. . . . . . , . . . . . . . . • . . .
• ~ . . . . . . . • • . . " ' . . . ~ . • ' . ' . . • . . .
. . . .
~ ~ ' ~ . . . • . . • . , . . . .
. . . . •
. . . ; : •
BENCH~
. ,
• • . .
, .
.
(vegetation on
, . bench not shown) ~
~ . . - . .
. . . CHANIyfL'.
~ . • ' . BED•.:•:.
~
~
~ Design Guidelines 7-3
~
~
for example, can be as much as 50 percent greater susceptiible locarions up- or downstream of the
than the average velocity at that cross-section project area. The upstream end of the facility in ~
(Maynord et al. 1989). Analytical methods for particular must withstand the greatest forces. In
estimating velocities in curved channels andlor general, structures should be continued to an area
engineering judgments are used for predicting the of reduced velocity. If not, erosion may remove ~
effects of the outside of bends and other hydraulic bank materials from behind the face of the struc-
factors on the local velocities. Occasionally, the ture. This gready weakens the facility and can ~
designer will be faced with placing protection cause possible failure.
along a straight channel reach. In these cases, the Another method of tieing in is to construct a
local velocity is often less than the average veloc- rock deflector at each end of the facility. This ~
ity. Methods for estimating local velociries are deflector acts as a hardpoint that deflects flows
discussed further in Appendix C. away from more vulnerable point along the bank.
Extent of Protection. Many designers mistak- This is particularly valuable at the downstream ~
enly extend erosion protection too far upstream end of structures such as rock revetments.
and not far enough downstream, particularly for
structures on the outerbanks of bends (Figure 7.3). ~
The highest velocities generally occur at the down- 7.2.2 ROCK PROTECTION METHODS
stream end of the bend, and on the outerbank of the
straight section immediately downstream. Often, Rock protection methods include toe keys, ~
the erosion potential does not decrease apprecia- deflectors, and revetments. These methods are
bly until the channel straightens and the thalweg commonly used where bank materials are weak
crosses over to the opposite bank for the next bend. and water velocities are high. ~
The downstream movement of ineander bends
should also be considered. If not properly ori-
Rock Toe Key ~
Figure 7.3 A schematic of the minimum extent of At sites where tce erosion has been identified
protection required at a channel bend. as the mode of bank failure, stabilization struc- ~
(Adapted from Lagasse et ai. 1991.) tures should be keyed into the channel bed at the
bank toe. While this may be obvious where tce ~
~OW erosion is the major problem, all alluvial streams
scour dunng flood events unless the bed is az-
~mored with large material. If the stream is under-
~
going bed erosion, whether by general degrada-
tion or headcutting, structures must be protected
~ against undercutting.
~ y Rivers with highly mobile beds (i.e., large ~
w T,,,g,,,,,,,,„Vo,,,, fluctuations in scour depth) may require deep tce
°i*. key placement. Recent feasibility studies on the ~
. Tolt River and South Fork Snoqualmie Rivers, for
example, included a recommendadon to place the
tce key a minimum of three feet below the lowest ~
ented, the structure can deflect flows and create recorded thalweg elevation (Shannon and Wilson
erosion problems on the opposite bank. 1993a; 1993b). Both of these preGminary recom-
Tie In. It is important that the end points of the mendations require detailed scour analyses to de- ~
facility be tied into a stable bank area. Some bank velop the final toe key design.
protection measures such as riprap structures cre-. For large river environments, Lagasse et al.
ate "hardpoints" that can cause erosion at more (1991) recommends placing the riprap a minimum ~
7-4 Design Guidelines ~
of five feet below the original streambed eleva- Large rock may be added to the toe for habitat
~ tion. Alternatively, the potential bed scour can be purposes if it dces not create cuirents that cause
estimated, and the toe then placed deeper than the erosion problems. Rocks create habitat by provid-
predicted scour depth. Methods for accurately ing refuge from high flow velocities (a form of
~ predicting scour have been developed by cover) and creating scour holes. Rocks are usually
Richardson, Harrison and Davis (1991) and placed within the zone of highest flow velocities
Richardson, Simons and Julien (1990). Although and can be incorporated into the toe of a protected
~ the methodology specifically addresses scour in slope. Rocks used in this fashion are intended to
the vicinity of road crossings, it is useful in any create velocity refuges, rather than scour holes.
evaluation of bed scour. Habitat elements are discussed in greater detail in
~ Toe key dimensions depend on stream charac- Section 7.2.5.
teristics, level of protection, and type of structure. As an altemative to using large mck, it is
The major consideration in designing a toe key is possible to use smaller stone wrapped in a natural
~ the proper sizing of the rock. The rock must be or synthetic geotextile material. Because abrasive
large enough to remain stable under the flow sediments and debris will wear, snag and tear these
depths and velocities to which it will be exposed. fabrics with time, high flows may remove this
~ Typically, rocks will need to have a minimum smaller rock. This can potentially undermine the
dimension of two feet or a minimum weight of at structure and cause it to fail. The geogrid material
least five hundred pounds. Over-sizing the rock should have high tensile strength and resist corro-
~ should generally be avoided because of increased sion and abrasion. The diameter of the rock fill
cost and difficulty of placement. used in the wrap must be greaterthan the size of the
~ The toe key can be difficult to construct in grid openings but should not exceed six to eight
rivers with high banks. In these situations, it is inches. If larger stone is used, there should be
extremely difficult to reach down from the top of sufficient small rock to fill voids bctween the large
~ the bank with a dragline to key rock in at the toe. stones so that the fill cannot shift and allow the
An alternative is to design a bench at ordinary high structure to settle over time.
water that can be used as a construction platform.
~ The bench can be left as a permanent feature which
then allows the upper bank revetment to be set Deflectors
back from the main channel of the river.
~ The width of the tce key is not as critical as its Deflectors are structures that are attached to
depth. For riprap revetments, the nunimum width one bank and project into the flow (Figures 7.4 and
of the key should be 1.5 to 2 times the thickness of 7.5). Commonly referred to as spurs or spur dikes,
~ the riprap blanket at the base of the slope. If used deflectors protect erodible banks by directing the
with cribwalls and vegetated geogrids, the toe flow toward the middle of the channel. They are
need not extend beyond a line formed by extend- useful in reducing meander migration and water
~ ing the slope angle of the structure to the maxi- velocities near the bank. The scour holes that form
mum key depth. around deflectors can provide rearing pools and
Quarried stone is recommended because an- cover for fish.
~ gular rock tends to interlock, which makes it more The design variables most used for deflector
stable. Using rounded stream rock is discouraged design are: orientation angle, effective length,
because it is less stable. In stream areas where the crest height, placement site, construction material,
~ rock has formed an armor layer, its removal by spacing between multiple deflectors, and deflec-
mining operations may cause local scour prob- tor construction materials. The following is a list
~ lems. Irregular rocks should be placed with the of recommendations and options, not strict rules
long axis parallel to the flow. Only hard rocks, for designing deflectors (Conner 1991):
such as granite or other volcanic rock that will not Orientation Angle. Deflectors onented up-
~ erode rapidly, should be used. stream create larger and deeper scour holes than
Design Guidelines 75
~
~ .
perpendicular or downstream oriented deflectors constriction or solidity is represented by the effec-
~ (Klingeman et al. 1984). Deflectors oriented up- tive length o~ e deflector (Le) compared with the
stream may also be the most unstable. The eddies channel wid(W).
that form on the upstream face of the deflector may The deflector must be long enough to deflect
~ scour a longitudinal hole along the bed, undernnin- the flow away from the length of bank to be
ing the structure and causing it to roll forward protected, unless riprap or another secondary bank
(Owusu and Klingeman 1984). The eddy formed protection is used. Several shorter deflectors may
~ in the pocket between the upstream oriented de- also be used to protect the same length of
flector and the bank protect the bank from higher streambank as one long deflector. Miller and Kerr
velocities. If the eddy velocity is sufficient to (1984) found that a deflector could protect the
~ transport local bank materials, it will scour the downstream bank for 2 to 5.5 times its effective
bank and undermine the structure (Copeland 1983). length, depending on the expansion angle of the
~ Deflectors oriented downstream direct the flow flow. Severe channel constriction may cause a
away fromthe bank along the deflector (Klingeman
et al. 1984). Because the flow deflectian angle Fi ure 7.5 Schematic dic,gram of a defkctor.
~ approximates the orientation angle, the designer 9 (AdapteJ Conner 1991.)
can predict where the flow may impinge on the
opposite bank (Klingeman et a1.1984; Reeves and
~ Rcelofs 1982). These areas may be protected by . . :
riprap, vegetation, or by placing another deflector
: . : . . .
. to intercept the flow. The downstream orientation
~ causes less flow deflection, and therefore, little or
no scour of the opposite bank (Owusu and Spacing
Klingeman 1984).
~ A downstream orientation is recommended at /B'
sites where bed and bank stability may be a prob- ~
lem. Additionally, debris and ice are less likely to w A
~ accumulate on downstream oriented deflectors ~
(Klingeman et a1.1984). For these reasons, down- L Le
J
stream orientation of these structures is generally
~ recommended (Federal Highway Administration Orle ftWn
1979; British Columbia Ministry of the Environ- ai+gie
~ ment 1980; Seehorn 1985; Wesche 1985).
Perpendicular deflectors may be the most cost- ~ B ' ~ ~ • . .
effective bank protection because the length of P~AN wew
~ bank protected is directly correlated with the ef-
fective deflector length (Copeland 1983). Because
perpendicular deflectors intercept flow at an abrupt ne;9h,
~ angle, they may also be more inclined to fail.
Special care should be taken in the design stage to .
prevent failure of single perpendicular deflectors. secr~oN A-n~
~ The perpendicular design is often used in combi-
nation with multiple deflectors to protect a length
of ba111C. . crest skope
~ Effective Length. The greater the channel con-
striction caused by the deflector, the greater the
velocity at the tip of the deflector and the greater secTioN e-s~
~ the scouring potential of the flow. The channel
Design Guidelines 7-7
i
. ~
sharper expansion angle, and thus decrease the Deflectors that are 'designed to be overtopped
length of bank protected per length of deflector at high flows should be shaped so that the flow is ~
(Klingeman et al. 1984). Miller and Kerr (1984) not directed into erodible banks at high flows
found in flume studies that the optimum effective (Federal Highway Administration 1979). An up-
length for bank protection was 0.2 of the flume stream oriented deflector or triangular shaped de- ~
width. flector will shunt high flows toward mid-channel
Recommendations for effective length in the and cause deposition along the bank.
literature range from Le/W of 0.25 to 0.8 (Seehorn Spacing of Multiple Deflectors. A series of ~
1985; Wesche 1985; Crispen 1988). Although deflectors can be used to protect a length of erod-
these authors claim that deflectors may block as ing bank. The goal is to redirect the thalweg away ~
much as 60 to 80 percent of the flow area; these from the eroding bank. The deflectors should be
deflectors would likely create adverse effects and spaced so that the flow expanding downstream of
fail. Thus, deflectors that block significant portion one deflector is intercepted by the next and redi-
of the flow area are rarely practical. rected toward the opposite banlc. To determine ~
Deflectors can create effective fish habitat by deflector spacing on the outside bank of bends,
producing scour holes. To create scour holes that Miller and Kerr (1984) suggest projecting the ~
benefit fish, deflectors must be long enough to tangent of the thalweg from the tip of the upstream
intercept a substantial portion of the flow. Garde et deflector to the bank downstream. The down-
al. (1961) found that in straight reaches, the depth stream deflector should be designed to intercept ~
of scour was 0.2 to 0.5 the effective length of the this flow. They suggest that the spacing be reduced .
deflector. Lagasse et al. (1991) provide criteria for by 20 percent on sharp bends. The thalweg of the
predicting scour depth at deflectors. stream straightens at high flows and thus will ~
Unless desired, the deflector should not be so impinge on the bank in the downstream portion of
long that it directs the flow into an erodible oppo- a concave bend (Miller and Kerr 1984). Deflectors
site bank. The opposite bank may be protected or should therefore be placed closer together in the ~
a deflector may be placed downstream on the downstream portion of a concave bend to protect
opposite bank to intercept the flow. If the deflector the bank at high flows (Reeves and Roelofs 1982).
is submerged at high flows, it may extend across a For the most effective bank protection, deflec- ~
greater portion of the channel without causing tors should be spaced close enough so that flow
erosion of the opposite bank. will circulate between the deflectors, creating a
Crest Height. If the risk of flood damage to buffer zone of eddies that protect the bank from ~
adjacent roads is of concern, deflectors should be higher velocity flow (Copeland 1983). Klingeman
submerged at high flows so that they do not catch et al. (1984) found that the optimum spacing for ~
debris (Federal Highway Administration 1979; developing this protective eddy system varies be-
British Columbia Ministry of the Environment tween three and four times the effective deflector
1980). Seehorn (1985) suggests that this condition length and decreases as deflector length increases ~
will be met if the deflector is no more than 6 to 18 beyond 0.2 of the channel width. Spacing deflec-
inches above average summer low flow level. tors too close reduces sediment deposition be-
Deflectors should be no higher than the top of bank tween structures (Crispen 1988). ~
and slope downward to the tip to prevent under- Airangements of multiple deflectors for vari-
mining (Franco 1967). Deflectors with a sloping ous purposes have been recommended in the lit-
crest have to be longer than level crested deflectors erature. Spacing deflectors such that their flow ~
to achieve the same amount of bank protection and patterns interact creates more scour and diversity
bed scour (Klingeman et al. 1984). To maximize of habitat than they do individually (Heiner 1989).
deposition, a series of deflectors can be arranged Pairing deflectors opposite each other centers the ~
so that the crest of each deflector is lower than the thalweg and creates a long, deep plunge pool
one just upstceam (Franco 1967). (Federal Highway Administration 1979). Alter-
nating deflectors can be used to help re-establish ~
78 Design Guidelines ~
orcreateameanderpattern(Wesche1985;Crispen aesthetic concerns, most of these methods have
1988). not gained acceptance in King County. Because
~ De.flector Construction Materials. The most the most common revetment in King County is
common construction materials used for deflec- rock, the remainder of this discussion will focus on
~ tors are rocks and logs. Rock deflectors can be this material.
constructed of two to three rows of interlocking Riprap revetments are patticularly effective in
rocks extending out into the flow (Federal High- the following situations: 1) sharp bends; 2) con-
~ way Administration 1979; British Columbia Min- strictions, such as bridges, where velocities in-
istry of the Environment 1980). The largest rock crease; 3) along the opposite bank at the confluence
should be placed at the tip of the deflector as this of two rivers; and 4) on rivers where debris dam-
is the zone where maximum velocity occurs. Rock age may occur.
size can be less than that recommended for fishrocks Limi ta tions. Rock revetments have several
as discussed in Section 7.2.5. limitations. These include environmental impacts
~ Blunt, wedge-shaped rock deflectors should such as the destruction of fish and wildlife habitat,
be used for bank stabilization. These create less encroachment into the floodplain, and loss of
flow disturbance and therefore are less likely to aesthetic values. Rock should not be prescribed
~ cause scourirrg of either the bed or banks. Single without first carefully considering other alterna-
lazge boulders, when properly placed, may act as tives. Even where rock is absolutely necessary, an
flow deflectors (Oregon Chapter of the American attempt should be made to incorporate vegetation;
~ Fisheries Society 1988). the structure should be sufficiently set back from
Rock deflectors should be embedded in the the channel to enhance rather than degrade ripar-
bed and banks to prevent undermining. The depth ian environments and instream habitat.
~ that the boulders should be embedded depends Other factors that may limit the use of rock
upon how much scour is expected around the base include the availability of suitable-size rocks, the
~ and root of the structure. Orsborn and Bumstead difficulty and expense of quarrying, transporting,
(1986) recommended rock deflectors be embed- and placing stone, and the large amount of mate-
ded for a distance equal to the height of the rial needed for deeper streams. While small nprap
~ deflector. may be hand-placed, most is end-dumped orplaced
by derrick crane or other large equipment.
Gradarion. For riprap to function properly, it
~ Rock Revetments is essendal that it be well-graded. A reasonable
gradation will allow the various rock sizes to
A carefully placed layer of angular rock, gen- interlock and minimize voids in the structure. It is
~ erally known as riprap, is a common and effective essential that there be no significant gaps (missing
method of bank protection used on levees and sizes) in the gradation. Gaps in the gradation
revetments. While rock offers some resistance increase the chance of structural faiiure if high
~ against mass-movement, its primary purpose is to flows remove smaller rock particles, causing larger
prevent loss of bank material by fluvial erosion. particles to settle. Wittler and Abt (1990) found
Because the system is flexible, riprap can settle that a relatively uniform gradation can withstand
~ and conform to the final streambed contour if . greater erosive forces. Failure of these rock facili-
scour occurs. Over time, vegetation may become ties, when it occurs, can be more rapid than those
established in riprap above the waterline. facilities having a broader ,gradation.
~ Revetments have typically been constructed Because many standards have been devel-
from hand-placed, dumped, or derrick-placed rock. oped, the riprap gradations--along with the me-
Many types of structural facings have been used. dian stone size--should be specified in the design
~ These include: riprap; gabion mattresses; rubber plans. The standard gradations generally used in
tire networks; articulated, precast concrete blocks; King County have been those developed by the
and cellular grids. Because of environmental and Washington State Department of Transportation
~
Design Guidelines 7-9
~
~
(DOT). These range in size from quarry spalls, mended. Encroachment that can not be avoided
through light loose riprap, to heavy loose riprap. will require an exemption from the floodplain ~
The specific sizes of this material, and the methods regulations contained in the King County Sensi-
for computing the size appropriate for a specific tive Area Ordinance. Grading of the slopes may
site, are described in Appendix C. increase right-of-way requirements. It is also ex- ~
Filter Layer. Most riprap is placed on a filter tremely difficult in situations where existing build-
blanket of smaller sized, graded material. A proper ings, other structures, or large mature, vegetation
filter layer prevents the loss of finer soil particles are located near the existing top• of bank. ~
of the bank through the intersdces of the riprap Shape of Rock. As noted in the tce key discus-
layer. If these finer soil particles are lost, slumping sion earlier, angular rock is preferred to rounded ~
and failure may occur. The area to be covered with rock because the stones fit together to provide a
a filter blanket should be reasonably smooth. An more solid blanket. Because this strengthens the
even thickness of filter material should be placed revetment so that it acts like one structure rather ~
on the prepared surface. Riprap should be placed than a collection of independent stones, it raises
carefully to ensure that the blanket is not ruptured the threshold velocity for incipient motion and
or displaced. For most of the rivers in King County, subsequent failure. Quatry rock is preferred to ~
a filter layer of gravels or quarry spalls is recom- natural river rock as it is generally angular; river
mended. Relationships between sizes of riprap rock is usually rounded and unacceptable as riprap.
and gradations of adjacent layers have been devel- While the rock should be angular, ideally it should ~
oped to size the individual rocks in the filter layer. be as nearly rectangular as possible. The ratio of
These relationships are discussed in detail in Ap- the longest to the shortest dimension should be no
pendix C. more than 3.5:1 (USACOE 1991). ~
Geotextile fabrics have sometimes been used Toe key. As discussed earlier, lack of a suffi-
to create this filter. It can be more difficult, how- cient toe key is a common cause of bank and riprap
ever, to key a large rock blanket into fabric than failures. Because tractive forces are greatest in this ~
into a blanket of smaller rock. Fabric filters are zone, a well-constructed toe is essendal. If the toe
most useful when the banks consist of fine-grained is not sufficiendy deep and effectively keyed into
alluvium. Banks with extremely fine-grained soils the streambed below the anticipated scourline, the ~
such as silt or clay may require both a geotextile entire structure may be undermined.
fabric and a rock filter. Height of Riprap Face. In determining the
Bank Slope. Because steep slopes lessen the height of the riprap face, a factor of safety (related ~
stability of the total structure, rock should not be to water surface elevation) should be incorporated
placed on slopes steeper than 2H:1 V. Steeper into the design. For installations that are com-
slopes may require a retaining wall or other struc- prised of riprap only (as opposed to vegetative or
ture. Maynord et al. (1989) state that stability tests integrated methods), Lagasse et al. (1991) recom-
have shown that slope has small effect on riprap mends extending the riprap to a minimum of two ~
stability when side slopes are flatter than 2H:1 V. feet above the design water surface elevation.
Because high flows can saturate river banks (cre- Riprap should extend up the bank far enough to
ating failure in the underlying material), it is vital provide adequate protection against scour by de-
that the revetment face slope does not exceed the bris, flowing water, or wave action.
angle of repose of the underlying layer. In situations where the natural channel has
Because riprap is usually installed at sites of been constricted, the designer will often find that ~
severe erosion wfiere the existing side slopes are the capacity of the channel is insufficient to con-
often steeper than 2H:1 V, substantial site grading vey the design storm. In these cases, either rock
is often required. When needed, the bank slopes protection should be provided to the top of the ~
should be laid back away from the channel where bank or construction a setback levee should be
possible to obtain the appropriate slope angle. considered. If sufficient space is available, a set-
Encroachment into the channel is not recom- back levee is the preferred alternative. ~
7. 1p Design Guidelines ,
r
When flood containment is a project objective, vegetation in levee and revetment faces. For this to
~ the design water surface elevation should be ad- be successful, the vegetation must come into con-
justed to account for the superelevation resulting tact with the soil undemeath or within the riprap
from centrifugal forces at bends. Chow (1959) armor. Depending on the season, urigation may
~ provides methods for computing superelevation. also be necessary.
Freeboard should be added to this superelevation
estimate. The Corps and FEMA both may require
~ three feet of freeboard above the 100-year water Other Rcek Structures
surface as a factor of safety for levees (see Section
5.8 for further discussion). Many other types of rock structures haive been
~ Vegetation. Vegetation on the face ofthe riprap used successfully for bank protection. These in-
structure can be an important component of bank clude tuming rocks, tie-backs, and rock-fill
stability. In the past, maintenance of riprap struc- trenches. Because a detailed discussion of these
~ tures often involved periodic removal of all veg- structures is beyond the scope of this document,
etation under the assumption that this would im- they will be described only in general terms. The
prove access and visibility for inspecting facili- reader is refened to Orsborn and Bumstead (1986)
~ ties, and that large vegetation, if uprooted, could and Lagasse et al. (1991) for further information.
severely damage the riprap face. Turning Rocks. Tuming rocks are mws of
~ Recently, regulatory agencies, such as the boulders placed in a bend starting at the upstream
Washington Depattments of Ecology, Fisheries, outside bank and angled toward the inside bank to
and Wildlife, have required the incorporation of reduce erosion (Figure 7.6). Turning rocks reduce
~ Figure 7.6 Turning rocks used to reduce erosion on ihe outside of a bend.
~ • . : Flow . .
~ ' ~ • Flow
Tuming V rocks
~ . • ("`J ' '
~ . . .
~ 0 • • . 2/3 - 3/4
flow
1/4 - 1 /3 ,
flow
Point ~
bar . . ~
L
~ L w
. _ Additional'~_-
o rows of rocks,
as needed Detail of turning rock
' .
~ Eroding
bank PLAN VIEW
~
Design Guidelines 7-1 1
i
the spiral currents that erode the outside bank of a either lay flush against it or protrude slightly into
bend. They also help dissipate energy to reduce the stream channel. Tie-backs protruding into the ~
stream power locally and provide cover for fish. channel create hardpoints that provide some en-
Turning rocks are placed in a downstream ergy dissipation. In this way, protection from
diagonal across the stream to deflect the flow. erosion is provided without hardening the entire ~
Each successive rock divides the flow and deflects streambank. Because much of the existing bank
the majority in the desired direction. The next rock line is left undisturbed, a favorable environment
downstream is placed to intercept the deflected forthe establishment of native vegetation remains. ~
flow from the upstream rock and so on. The Tie-back revetments are created by connecting the
longest axis of each rock should be positioned at a hardpoints with a rock revetment or toe key. ~
slight angle to the flow (Orsborn and Bumstead These structures ane not effective forextremely
1986). high velocity flows. They are most useful in rela-
Turning rocks can be used to direct the flow tively straight reaches where the primary erosion ~
away from an unstable bank orto direct the thalweg threat is a meandering thalweg. On the outside of
down a selected part of the channel. Several rows bends, a revetment or a series of rock deflectors is
may be needed depending on the length and radius usually more appropriate. ~
of the curve (Orsborn and Bumstead 1986). Be- Rock filled Trenches. A rock-filled trench is
cause turning rocks may not be adequate to turn placed parallel to the bankline such that the rock
the flow by themselves; especially in deep streams can fill scour holes and/or scalloped banks as ~
or rivers, other structures such as deflectors may erosion progresses. The trench is dug behind the
be needed to provide adequate protection from bank of the channel and filled in with riprap. The
erosion. trench is then covered with a layer of soil and ~
Tie-Backs. Tie-backs are individual seetions replanted. This method does not modify the chan-
of riprap or other structural protection placed nel and yet provided the riprap trench will halt
perpendicular into an eroding bank to prevent erosion if it occurs. This method provides addi- j
flanking by floodwaters (Figure 7.7). Depending tional protection when greater security is required.
on the design, they are placed against the bank, and ~
Figure 7.7 Tie-back trench and revetment io prevent flanking. (Adapied from Richardson et al. 1991.)
~
-
~ ~ ~1 I I II ~ I 1 ~ •At`.
~ ~ .
ti
•
~ ~r r
Tie-back trench
fiiled with riprap
E--! -
Riprap
- -
~pW,<•~,;. ~
\
\ . ~
7-12 Design Guidelines ~
Another application of a rock-filled trench is sion control until woody vegetation becomes es-
to construct it within the channel itself, immedi- tablished or where cover on bare ground or soil
~ ately adjacent to the toe of the bank. As bed scour improvement is desired. Sod-fomung grasses and
occurs, the rock settles in to the degrading toe. legumes, especially if left unmowed, can protect
~ ProtecNon from undermining is provided as long banks of small streams where flow velocities are
as the eventual depth of scour does not exceed the low.
capacity of the quantity of rock used. In rapidly Grass species recommended for western Wash-
~ eroding river environments (outside of bends, ington streambanks are listed in Table 7.1. Al-
etc.), a keyed-in toe is preferable to a rock-filled though individual species are listed in this table, a
trench type. mixture of species may be more successful and
~ desirable than a monoculture. Erosion control
seed mixtures are commercially available, and can
7.2.3 VEGETATIVE METHODS be tailored for site conditions. Seed mixtures should
~ . include annual and perennial species and species
Vegetative methods include herbaceous ground that will enrich the soil (e.g., legumes). The need
covers, rooted stock, live stakes, fascines, brush for fertilizers should tie evaluated and appropriate
~ mattresses, and brush layers. While the root sys- kinds and amounts applied. Local Soil Conserva-
tems of these components increase the "structural tion Service personnel are a valuable source of
integrity" of a bank with time, their initial value is information about specific plant requirements.
~ in protecting the bank surface. These methods Wasser (1982) provides an excellent summary of
usually can be installed with minimal instream grasses, forbs, shrubs, and trees useful for reveg-
~ disturbance. etation projects in western states.
Evaluation factors for selecting the appropri- The use of grass and forb turfs to protect
ate plant species and method of application in- streambanks is constrained by velocities of design
~ clude slope, aspect, soil characteristics, drainage, flows. At present, information on design veloci-
elevation and tolerance of the plant species to ties for native grasses is not readily available.
inundation. Much of this is discussed in Chapter 6. Examples of maximum allowable design veloci-
~ Ideally, the selection of vegetation should be re- ties for other selected grasses are listed in Table
stricted to native species that are suited to the site 7.2.
conditions. While unmowed turf also can provide habitat
~ Plants should be chosen based on their adapt- for small mammals and ground dwelling birds,
ability and tolerance to soil moisture levels, espe- thick turf or grasses may hinder the establishment
cially on very wet or very droughty sites. The plant of woody vegetation by competing for water and
~ associations in Table 6.4 include many species nutrients. Thick turf may also encourage popula-
suited to particular conditions. Planting plans. tions of small rodents that girdle trees and shrubs
should be designed using subsets of this list or when feeding on bark.
~ other species as appropriate, depending on site-
specific conditions and stock availability.
Rooted Stock
~
Herbaceous Ground Cover ' Rooted stock is any tree, woody shrub, or
herbaceous plant with established roots. This in-
~ Herbaceous ground covers include grasses and cludes rooted cuttings, balled and burlapped, bare-
other non-woody vegetation. Although they lack root, and containerized .plants. This material is
some benefits of woody vegetation (e.g. cover for used either alone or with other methods to provide
~ fish), herbaceous vegetation is useful in some
situations. Ground cover provides temporary ero-
~
Design Guidelines 7-13
~
~
Toble 7.1 Grosses and ground covers recommended for use on and adjacent to channel banks in western
Washingron. (Adapled from SCS 1986.) ~
Recommended Seeding Rates For Given Site Conditions'
Species Shallow or Dryland Irrigated or Palustrine ~
Droughy Suk}irrigate2 orWetland
tall Fescue Festuca arundinacea 18 18 18 ~
creeping red fescue F. rubra 8 8 8 ~
sheep fescue F. ovina 5 5
bentgrass Agrostis spp. 1 1 ~
perennial ryegrass lolium perenne 15 15 ~
tiny white clover Melilotus alba 10-15
big trefoil Lotus crassifolius 4 4 ~
white or Dutch clover Trifolium repens 2 2 ~
red clover T. protense 4 4
sicklekeeled luPine !uPinus albicaulis 10 10 . 10 ~
l. Minimum seeding rotes in Ibs/acre. ~
2. Includes sites receiving exrrc moisture from iunoff, snowmelt, stream wvter, e►c.
. ~
Table 7.2 Excmple maximum albwable design velocities for channels vegetaied with selected grasses.
(From Simons, li, and Associates 1982.)
PERMISSIBLE VELOCITY (fps)
Type of Grass Slope Erosion Easily ~
Range Resistant Soils Eroded Soils
Bermuda grass Cynodon spp. 0-5 8 6 ~
5-10 7 5
over 10 6 4 ~
Buffalo grass 8uchloe spp. 0-5 7 5
Smooth brome Bromus inermis 5-10 6 4 ~
Blue grama grass Bouteloua gracilis over 10 5 3,
AlFalfo Medicago sativa 0-5 3.5 2.5 ~
7-14 Design Guidelines ~
~
leafy coverand root strength because it sends roots some sites may require urigation for one or more
~ into the surrounding -soil in weeks rather than seasons.
months that cuttings may take. It may be placed
anywhere on the bank where it will not be removed
~ by erosive flows. Live Stakes and Slips
Rooted stock should be used for planting dur- .
ing the growing season when unrooted cuttings A quick and effective means of securing a
~ may not survive. It is also useful where soils are vegetative cover for control of soil erosion and
droughty, nutrient poor, where rooting of cuttings shallow sliding is planting unrooted cuttings. Live
is doubtful or when cuttings of desired species are stakes are woody plant cuttings that can root, and
r unavailable. Species that do not root readily from are large and long enough to be tamped into the
cuttings such as conifers can also be incorporated ground as stakes (Figure 7.8). Live stakes are
~ into designs in this manner. Rooted plants may be generally cut from wood that is two or more years
added where understory vegetation already exists old. Slips are similar to live stakes, but smaller in
and larger shade-providing plants are desired. size. Slips, which are cut from first or second year
~ Rooted stock provides immediate vegetative cover wood that is still soft and flexible, are not strong
and habitat improvement. enough to act as anchors.
Spacing of rooted stock is dependent on the Cuttings from plant species that root easily
~ eventual size of selected species. Depending on will grow if planted under favorable conditions. It
the root distribution needed, plants may be spread is well known, for example, that most willows,
evenly across the site foruniform coverorclumped many poplazs, and cottonwoods, readily grow .
~ for a more natural appearance. The plants vary in from cuttings set in moist soil (Gray and Leiser
size from small (inches) to large (10 or 12 feet tall). 1982). Even in very unfavorable conditions (e.g.,
Containerized stock has a relatively high cost per deep shade), live stakes will often grow vigor-
~ plant. Even with established roots, rooted stock at ously for a few years before they die out. During
~ Figure 7.8 , live siakes. ,
e /Qp
~
0
,
~ . ~ •,il
r. .
~ ~J~ . •
F„ ; •
I
~ .
~ ~i • ' . ' • .
~ .
Live stake prior Note: Shown
~ to installetion after one growing season.
~ Design Guidelines 7 15
~
this time, they will stabilize and modify the soil, material. Live stakes can be interplanted with
and serve as pioneer plants until other plants can rooted stock. ~
become established. Live stakes are effective in
camouflaging an open area after one or two grow-
ing seasons. Over time, the cover provided by live Fascines ~
staking creates riparian and wildlife habitat.
Live stakes are useful alone or when used with Fascines are sausage-like bundles of long, live ~
straw, jute mesh, and coir (a coconut fiber mesh) cuttings tied together and secured to the bank with
for providing surface protection and in controlling live and dead stakes (Figure 7.9). They are placed
small rills and gullies. They are also effective on the bank face in shallow trenches and lightly ~
when construction time is limited, an inexpensive covered with soil. These are also called wattles or
method is necessary, the problem is very simple, contour wattles.
or when work in the channel is not allowed or Fascines are useful for areas of general scour ~
desirable. Slips are useful for small projects with where the banks can be sloped back. They work
similar characteristics and sites with soft, moist particularly well in straight sections where flow
soil. While live stakes and slips require moist soil velocities are low. Fascines offer inexpensive and ~
to root, excessive water will result in rotting. immediate protection from erosion, especially from
The density of the installation ranges from two overland flows moving downslope. They usually
to four live stakes per square yard. Live stakes do not require work in the channel. ~
should be spaced approximately every two feet in Fascines work well to reduce erosion on shal-
a random to triangular pattern. For slips, higher low gully sites and help in controlling surface
density (about 12 cuttings per square yard) at one erosion by reducing the slope into a series of ~
foot spacing is recommended. Live staking re- smaller slopes. They are an effective stabilization
quires a moderate to large volume of live plant technique once installed and even more so when
roots become established. Fascines help hold soil ~
Figure 7.9 Fascines. ~
Live or
dead stake . . . , ~
v8ries • AFTER TOPSOIL . ' ' .
• COVERING ' • . •
. . • AT TIME OF ' - ~
- . • . ' ' INSTALLATION, ~ •
w Fascine or wattle bundle ' . . , ~
. . . . . . . . • . . . ' ~
' ' . . ~
. ~
. • Shallow trench
with fascine
~
7-16 Design Guidelines ~
~ on streambank faces by creating mini-dam struc- Used alone, bivsh mattresses provide some
~ tures or terraces. The erosion control capabilities bank protection and erosion control; they can
of this system can be enhanced by using straw, jute resist temporary inundation, but not undercutting
or coir mesh to cover surface areas between (Gray and Leiser 1982). Structural measures such
~ fascines. These materials provide stable growing as toe keys or revetments may be necessary if bank
surfaces that help the invasion of surrounding undercutting is occurring. Brush mattresses are
riparian vegetadon. useful where banks can be graded to a 3H:1 V or
' The fascines should be spaced three to five feet 4H:1 V slope. Construcdon of these units creates
apart on contour, parallel.to the stream (Schiechtl small disturbance. Because established brush mat-
1980). Installation should begin at the wetted edge tresses reduce local velocities, they are useful
r of OHW and continue up slope. where debris and sediment need to be captured.
Brush mattresses provide immediate protection
against flowing water and establish a dense natural
~ Brush Mattresses riparian zone in one or two seasons. The capabili-
ties of this system increase with age.
A brush mattress is a combination of units that Brush mattresses are generally used to cover
~ cover the streambank to provide immediate pro- six to ten feet of vertical bank face. This method
tection. The units used in this method are live and requires a very large amount of live material.
~ dead stakes, fascines, and a mattress-like branch .
cover (Figure 7.10).
'
Figure7.10 Brush nwMness with a fascine.
~
~
, .i ( .
Ir ~
~ Uve or dead stake r , ~ . • • ' ' . . .
( ~ ~ ~ •
Uve branc,es 1 r
~
,
Wire or jute rope
~ ~ ~ . :
Fascine
(optional) ~ . ~ ' . ' . . .
~ . ' J i/ r ~ • ' . . ' • . .
~ • .
v _
. . r i i . . , .
~ ~ % . • . .
~ .
Note: Topsal
cover not shown.
~
Design Gu'idelines 7-17
,
~
Brush Layers 7.2.4 1NTEGRATED METHODS
Brush laYers are altemating layers of soil and Integrated methods incorporate vegetation, ~
live branches on successive horizontal rows or soil, timber and rock. These methods include joint
contours in the streambank. The buried portion of planting, vegetated geogrids, live cribwall, and ~
the branches root to form a permanent reinforced tree revetments.
installation, while the tips produce vegetative top
growth (Figure 7.11). ~
Brush layers are useful in bank protection Joint Planting
projects requiring fill, or as a rehabilitation mea- ~
sure for seriously eroded and barren banks (Gray This method consists of live stakes driven
and Leiser 1982). They produce an immediate among rock riprap. It increases the effectiveness
barrier that repairs gully erosion and local scour of the armored system by forming a root mat and ~
holes. They effectively repair holes in earthen reinforced filter system in the base upon which the
embankments. While the construction of brush riprap has been placed (Figure 7.12). It also helps
layers generally does not require work in the collect sediment and debris. Because joint plant- ~
channel, earthwork related to the installation of ing creates no channel disturbance, it is useful
the layers may cause some disturbance. Brush where rock work has to be accomplished in the
layers, however, rapidly produces habitat cover summer. Once the rock is in place, live staking can ~
and a stable vegetated bank. be done later without further disturbance to the
Installation of brush layers is best during low channel.
flow conditions. This method requires a relatively This method improves areas where riprap is ~
large amount of live branches. already in place and habitat, recreational, or aes-
~
Figure 7.11 Brush layers. ~
~
AFfER TOPSOIL •
COVERING
•ATTIME.OF ~ ~
INSTALLATION • •
Live brush ~ • • ~
. • . . ~
~
~
7 18 Design Guidelines ~
thetic values are desired. It enables a streambank als are wrapped around each soil lift between the
~ to become more natural looking and function as a layers of live branches (Figure 7.13).
vegetated riparian zone. In time, roots will add to Vegetated geogrids are useful where slopes
the strength of the riprap protection. cannot be cut back or in bank locations requiring
~ The thickness of the existing rock layer is a addition protection against strong erosive flows.
major consideration in applying this technique. To The level of protection afforded by geogrids is
achieve successful rooting, live stakes must be greater than solely vegetative methods but may be
, driven through the rock voids and into the under- less than rock methods. Vegetated geogrids are
lying soil layer. Joint planting is more labor inten- useful where fill is needed to repair local or gen-
sive than ordinary live staking; it also requires a eral scour. They may be used to abate bank failure
~ moderate to large volume of live material. A plartt caused by toe erosion when combined with struc-
loss of 30 to 50 percent is common with this tural toe protection. If constructed with adequate
method especially in revetments with very thick soil compaction, geogrids can be constructed with
~ layer of riprap (Schiechtl 1980; Christensen and a steep face and thus are valuable for repairs at
Jacobovitch 1992). Irrigation during the first grow- sites where the banks can not be sloped back.
~ ing season can enhance plant survival. Vegetated geogrids immediately reinforce the
bank. While the benefits are similar to those of
brush layers, vegetated geogrids can be placed at
~ Vegetated Geogrid a steeper angles. Vegetated geogrids capture sedi-
ment that rapidly rebuilds and stabilizes the bank.
Vegetated geogrids are similar to brush layers They produce rapid growth for habitat and be-
~ except that natural or synthetic geotextile materi- comes very natural in appearance and function.
~
~ F'igure 7.12 Joint planting. .
qiPmP
_
,
' . .
~ • . ~ . .-r.. 1 :
•.T"r':i;•i:'
LIV@ 8t8k@ ii~. i: ~ 1
.
J:.
. . . .
. : .
~ ..•r:,:::;
~ . . . .
1 • . •
~ ' ' f .e : ; • ~ .
Live siakes . ,
: :~Y"i"s ~ .
~ ' ~
~
~ Design Guidelines 7-19
Fi9w+e 7.13 Vegehated geogrid•
~
Exposed face ot ' , ' • • : ,
geotextile materiel ~ , . . . .
Live brush : ; ~ • ;,r ~ • ' • . . . • .
• , ' ' I ' ' Geotextile ~
` .~i•n • '~J' material
; , ~ .
• •1•` - . .
, ' . % . • .
,t ~ . .
~
. • . ~ ~ ~ . . . Fili meterial
. . ~ ' . . •
. • . . '~A •+'I . • .
. • " ' . ' • . . . . • ~
~
Excellent overhanging material is provided im- flowing. It is useful for large areas of scour and to
mediately for aquatic habitat, and cover increases abate toe erosion when rock is placed in front of ~
over time. the structure. Because this method requires fill
Unless rooted stock is used, geogrids are best material, it is useful for restoring lost banks. If the
installed while plants are dormant. At sites such as area to be stabilized requires a larger-sized and ~
upper bank areas, irrigation during the first grow- more complex cribwall, the advice of an engineer
ing season may enhance growth and survival. knowledgeable in these designs should be con- ~
Plants may be installed during the growing season sulted.
if the plants are watered during the planting pro- Cribwalls can provide excellent overhang
cess. cover material for aquatic habitat. The log or ~
timber framework provides immediate bank pro-
tection, while the plants provide long-term dura-
Live Cribwall bility. ~
- Cribwalls need not be built to the top of the
A live cribwall is a rectangular framework of existing bank. Other methods, such as fascines or
logs or untreated timbers, rock, and woody cut- brush layers, work well on upperbanks. Cribwalls ~
tings (Figure 7.14). Live cribwalls are useful when should be built during low flow conditions as they
space is limited and slopes cannot be cut back. often require work in the channel bed. This method
They may be installed with finished streamside requiresamoderateamountoflivematerial.Regu- ~
slopes as steep as 1 H: l OV. They are effective in lar inspection is necessary the first year to identify
repairing eroding banks in outside meanders or and correct potential washout problems.
other areas where the currents are strong and fast ~
7-20 Design Guidelines ,
~ L
Fig,m 7.14 Live cribwau.
1
~
' Live branches ~ ,
.
. ^ 'f
'
~ • f' ' j / ~
~ ~
. . ' ~ Rockftll
' ' . . .=;:..r.
~
Tree Revetment damage or deterioration will expose the bank to
~ the current. If the revetment is not repaired, the
A pervious tree revetment, made from whole bank will continue to undercut and erode.
trees cabled together and held in place with rock Aesthetically, this method is acceptable in
~ and ' deadman anchors buried in the bank, is a natural settings. As it collects sediment and begins
relatively inexpensive, semi-permanent form of to revegetate, it becomes more natural in appear=
protection (Figure 7.15). Tree revetments are used ance and function. The rate of silting which occurs
~ where protection from bank scour and undercut- in the revetment area is dependent on the type and
ting is needed. Additional protection can be ob- amount of sediment being transported by the stream
tained by jamming large branches or small trees and the type of trees used.
~ behind ihe cabled trees. The stability of the bank
above the tree revetment can be increased by using
tree and shrub plantings. 7.2.5 FISH HABITAT COMPONENTS
j Trees with a trunk diameter of 10 to 12 inches
or lazger are required for good barriers on large Bank stabilization projects and other instream
~ streams or rivers. Smaller trees (two to four inch modifications can alter fish habitat by changing
trunk diameter) may be used on smaller streams. local depths and velocities, resulting in local scour
The most effective species are those with bushy or deposition at the stream bed or banks. Fish
~ tops and durable wood, such as Douglas fir or habitat may benefit from these changes if they
western red cedar. result in spawning gravel recruitment and create
Tree revetments have a limited life and must resting areas in feeding zones. Bank stabilization
~ be replaced periodically. Loss of trees through projects may also improve overwintering condi-
' Design Guidelines 72 1
Figure 7.15 Tree revehnent. (Adapied from Henderson and Shields 1984.) ~
~
i a~ , _ M _
+ •Y . %.1 ' t ,r .An
~1~~ yf / ~ ~ ~
'~v►~ s~~Y y+./"..'~, a^..~~ie~ .~.s~
~ . ~ ~y .%~'o~ • '
Cl: i '
Anchor rock
1 ~ Trenched-in cables
~ Deadman anchor
~ ~ ~
.
. ~
i-
ti ~
Vari@S
FIoK~,~, Overyap
~ -
~arieS
~
~
tions by increasing the available interstitial space design, an expert in these topics should be con- ~
and reducing water velocities. They can also pro- sulted to assist with incorporating habitat compo-
vide cover either as water depth, overhangs, or nents into bank stabilization projects. The type
visually isolated areas. The benefit of these effects and location of habitat components added to a ~
on fish habitat will depend on whether or not the river should be based on the stream gradient,
fish populations are limited by other factors in the channel geometry, basin hydrology, intended
stream basin. function(s) of the structure, and available materi- ~
The bank stabilization methods discussed ear- als and site accessibility (Heiner 1989). Stream
lier in this chapter can be improved by adding gradient, channel geometry, structural dimensions
features designed specifically to benefit fish. This and spacing, and discharge determine the forces ~
section describes two such features: large woody exerted on the habitat component. The project's
debris (e.g., trees or rootwads) placed into the habitat functions combined with the available ma-
bank; and boulders or boulder clusters (sometimes terials and site access determine which habitat ~
called fishrocks) placed in the channel. component that are feasible. These and other vari-
To successfully match the requirements of ables are discussed further below. ~
various fish species and life stages to a project
722 Design Guidelines ~
' .F
Discussion of and design criteria for full span- Disadvantages are lazgely associated with the level
~ ning structures, such as log and rock weirs that are of difficulty encountered when attempting to an-
commonly used for instream habitat modifica- chor each element in place.
tions, is beyond the scope of these guidelines. The longevity of any wood will be greatly
' While appropriate and needed in some situations, enhanced if it remains fully saturated (i.e., "water-
these structures are generally not constructed solely logged"). The maximum decay rate occurs with
to achieve bank protection. alternate wetting and drying, or consistently damp
' condition, rather than full saturation. Wood varies
by species in its durability and decay resistant
Large Woody Debris properties. Cottonwood and alder, even in the
' large sizes needed for installations along major
Large woody debris is any large piece of rivers, are the most rapidly decaying local tree
woody material (generally defined as 0.5 feet in species. While maple will also decay fairly quickly,
' diameter and at least 10 feet long) that intrudes or it is more durable than the other deciduous tree
is imbedded in the stream channel. Woody mate- species. It is unlikely that deciduous woods can be
~ rials affect local flow velocities, streambed and relied on to survive for more than 5 or 10 years at
streambank stability, and local stream morphol- best; water saturated maple may effectively double
ogy. Very large tree trunks or roots lodged against these estimates.
~ readily erodible streambanks, for example, can For maximum longevity, it is best to use more
significantly increase localized streambank scour. resistant coniferous species whenever possible.
The accumulation and burial of large amounts of Of the conifers, hemlock is poorly suited because
~ woody debris in the streambed can dramatically of its rapid decay rates. While very durable, Sitka
increase the stability of the reach against the mo- spruce is often very difficult to locate and com-
bilization of streambed sediments during higher paratively expensive because of its desirable lum-
~ flows. Woody materials lodged at various angles ber qualities and locally increasing scarcity. Dou-
to the flow can efficiently redirect the current to glas fir has excellent durability, especially when
enhance streambank stability. The presence of maintained in a saturated condition; it is aiso the
~ woody elements benefits fish habitat by greatly most abundant of the commercially managed soft-
increases the complexity of the currents, the en- woods. Westem red cedar, however, is the most
trainment and distribution of sediments, and local desirable of all native local species because of its
~ stream morphology. natural rot-resistant properties. Douglas fir will
When incorporating woody elements into bank generally survive for at least 25 to SO years, with
stabilization projects, it is necessary to identify the cedar lasting twice this length of time. Such lon-
~ desired engineering performance and the desired gevity puts these species within the normal esti-
habitat benefits. Each project must be specifically mates of the functional design lifetime expected
tailored to meet the engineering objectives identi- for conventional riverbank stabilization installa-
~ fied for the reach and the habitat requirements of tions.
the target species. Individual logs or aggregates of woody mate-
~ When selecting a design, it is very important to rial can increase local and/or reach-specific rates
consider the factors that influence the relative of erosion by deflecting or re-direcring flows.
permanence of wood in river systems. These in- Single logs, for example, aze frequendy placed so
~ clude the type of wood, its size and shape, its that they extend into the river at a downstream
exposure to the forces exerted by moving water, angle. When placed in relatively shallow flows,
and its resistance to movement because of wedg- the result most often obtained is increased turbu-
~ ing or embedding with adjacent materials. Woody lence with higher velocities both flowing around
materials can be obtained as cut logs, cut stumps the log and redirected into the bank just immedi-
and rootwads, or tree trunks with roots attached. ately downsveam of the log.
r Each has particular advantages and disadvantages.
, Design Guidelines 7-23
z ~
Conversely, placing logs at an upstream angle Fishrocks can be used to achieve many differ-
will deflect flows at right angles to the log away ent objectives, depending on where they are placed ~
from the bank and toward the center of the stream and how they are amanged (Figure 7.17). Al-
(Figure 7.16). Deeper, higher-velocity flows will though boulder placements are the simplest fish
incrementally scour a pool around and under the habitat structures, the hydraulics surrounding them ~
end of the log. This effect, when distributed over are complex. Careful planning and the use of
a series of logs placed along an,outer meander hydraulic criteria to choose and place boulders
bend, can effectively shift the deeper, faster flows will enhance their success. ~
away from the toe of the riverbank slope. Reloca- The fust step in predicting the results of rock
tion of the thalweg of the river, even by a modest placements is to analyze the existing flow patterns ~
distance, can markedly enhance the longevity and and streamlines in plan and profile view and then
performance of riverbank stabilization measures. visualize how the rock will change them. This can
then aid in estimating the pattem and extent of ~
scour and deposition.
Bouldeis/Boulder Clusters (Fishrocks) Clusters of boulders have several advantages
over single boulders. Boulder clusters provide ~
Fishrocks are large, iiregular boulders used to greater stability, have a greater diversity of depth
create fish habitat by producing a diversity of and velocities, and trap woody debris more effi-
velocities and depths. Additional cover and rear- ciently than single boulders. Additional cover for ~
ing areas are provided by the deep water, air fish is provided in the spaces between the boul-
bubbles, and turbulence around the rocks. In addi- ders.
tion, individual boulders or groups of boulders Irregularly-shaped, angular boulders of du- ~
may aid bank stabilization efforts by deflecting rable rock should be used. Abrupt boulder edges
flows away from unstable banks. ~
debris. ~
Figure 7.16 Bank protechon usmg large woody
~
FL~
Log with roots secured ~
• within rock toe.
Rock toe
I . . . ~
; . ,
~ , • ,,..y. , ,
: .a
. dN
. / /
h . . w/.%' 'q .f:' •
• • • •
Toe of bank ~
pHyyM Top of bank
r
724 Design Guidelines ,
~
Figure 7.17 Boulder dusim. (Adapted fnom Orsborn et al. 1985.)
~ . • • •
' ' ~ • , . . • - • • • . . , • o,~ ' ~
' .s~' ' o • , . • '
~ . . .
~ ~
~ .
- ~
Flow
~
J
~ _ . - , . . . . . 'O'' .
• ; , • • • . . . ' , • . . . ' . . ~ • ~ ; ~
~ • • . • • _ ' PLAN VIEW
'
r . .
o ~ . .
~
1 p
~ J
Suspends
Flow sediment ~
~ ..'.'',•'0 , J~.. ,.•I~O,•. •O. j..•..
' PLAN VIEW
Deposit . Scour
~
. 7-25
' Design Guidelines
Table 7.3 Recommended rock sizes for fishrocks. (Federol Highway Adminisiration 1979.)
~
Channel Width (ft.) Water Depth (ft.) length of Rock (R.) '
(summer flow)
< 20 1.0 to2.5 2Ato4A ~
20ro40 1.0 ro3.0 3.0 to8.0 .
40ro60 1.5to4.0 4:0 to 12.0
. ~
create turbulent eddies and enhance the scouring ment 1980; Ward and Slaney 1981; Moreau 1984; ~
potential of the rock (Cullen 1989). Angular rock House and Boehne 1985; Wesche 1985).
is also less likely to roll in the current (Moreau Highway agencies, concemed with protecrion ~
1984). The irregularities will provide additional of the roadway, advise that if potential flooding or
hiding cover for fish (Crispen 1988). bank erosion is of concern, high flows should
The boulders should not be so large that they overtop boulders to clear trapped debris (Oregon ~
cause bank erosion or overtopping. Maximum State Highway Division 1976; Federal Highway
scour occurs when the water level is at the top of Administration 1979). If the risk of damage to
the rock (Fisher and Klingeman 1984). The Or- property and improvements is low, debris should ~
egon State Highway Division (1976) recommends be left around fishrocks for additional cover.
that no more than one third of the channel area be Boulders with blunt faces create lazge up-
blocked. The Federal Highway Administration stream scour holes and then tend to tip into this ~
(1979) cautions that no more than one fifth of the hole (Fisher and Klingeman 1984; Cullen 1989).
summer low flow area be blocked unless the Rocks should be selected and positioned so that
stream gradient is greaterthan three percent. These this does not occur. Increased stability can be ~
recommendations may be conservative and over- achieved by placing boulders in clusters. Seehorn
simplified in that the stability of the rock and the (1985) recommends the use of boulder clusters ~
channel depends on many more factors than sim- over isolated boulders. While the scour pattern
ply flow blockage. around boulder clusters depends on the cluster
The rocks should be large enough not to be pattem, it often resembles a horseshoe. ~
washed away during high flows. The size of rock When placed in riffle and glide areas, boulders
required depends on stream size, flow characteris- can create pocket-like pools that provide resting
tics, substrate stability, and rock shape. Crispen areas for rearing or migrating fish (Rosgen and ~
(1988) suggests that fishrocks should be at least as Fittante 1986). Avoid placing rocks at sites with
large as rocks naturally maintained in the stream. fine or unstable beds that scour readily (British
The Federal Highway Administration (1979) Columbia Ministry of Environment 1980; Ward ~
recommends using 2-foot diameter, 1000-pound and Slaney 1981). As with blunt-faced boulders,
rocks in velocities of up to 10 feet per second and rocks placed in these sites tend to sink into their
4-foot diameter rocks in velocities of 10 to 13 feet own scour holes unless the substrate is armored ~
per second. In addition, they provide size guide- (Fisher and Klingeman 1984; Cullen 1989). Simi-
lines based on channel width and depth (Table larly, avoid placing rocks in depositional areas
7.3). Other suggestions from various sources sug- where the rocks may become buried by sediment ~
gest that boulders should be at least 2.0 to 6.5 feet (Ward and Slaney 1981). Occasionally, rocks may
long or have a volume of greater than 0.65 cubic be used in such areas to encourage deposition.
yards (British Columbia Ministry of the Environ- r
726 Design Guidelines ~
r
7.2.6 SUMMARY OF DESIGN contain a site plan, grading plan, layout, irri-
~ CONSIDERATIONS gation, planting, and detail sheets. The graph-
ics must be complete, accurate, and very easy
To help designers select solutions appropriate to read. They should be accompanied by
' for each situation, Table 7.4 summarizes each detailed written instructions, called construc-
method including relative quantities of material, tion specifications, which supplement and
major limitations, and costs. Installation proce- clarify the graphic on the drawings. An ex-
~ dures are discussed in Chapter 8. This table should ample of construction specifications is pro-
be used in conjunction with the numerous design vided in Appendix D.
, factors discussed in the previous .chapters. In addition to the elements described above
(specific quantities, densities, species), final
design plans should include: a key to symbols
' 7.3 DESIGN DRAWINGS, PLANS for deciduous and coniferous trees and shrubs,
AND SPECIFICATIONS paving, riprap, grass, and forbs; scale (graphic
or numerical value: graphic scales have the
' Conceptual designs explore ideas and rela- advantage of changing at the same rate as the
tionships among functions, activities, and spaces. rest of the page if enlarged or reduced); and a
They serve as a basis for further development, as Northarrow (Figure 7.18). A complete list of
~ a means of conveying graphic concepts to other information that should be included in the
individuals working on a project, and a medium final project drawings and construction docu-
' for feedback during the design development stage. ments is provided below:
They are rough sketches lacking detail, serving
mainly to get preliminary ideas on paper. There • Overall location plan showing access
' aze no right or wrong conventional symbols. to site from local highways (drawn at
During design development, the rough sketches any appropriate scale).
and ideas developed in the conceptual design • A drawing of the entire bank or repair
~ phase are tested and refined. The designer evalu- area, locating each type of treatment.
ates possibilities identified in the conceptual phase • Right-of-way and easement areas.
and rejects, adds to, or modifies them. This phase • An elevation drawing of the repair,
~ results in drawings that include specific informa- . identifying whether the elevation is
tion on spatial organization, material, and sizes of truly vertical or parallel to the slope.
features. Called "presentation drawings", these Include topographic information (one
~ are used to communicate ideas and obtain feed- foot 'intervals) of the existing and
back forlaterdesign refinement. Presentation draw- proposed contours.
ings should be fairly realistic and self-explana- • Existing river protection facilities and
~ tory, with limited text for labels. The level of detail ' channel hardpoints such as large rocks
provided is intermediate between conceptual and or bedrock areas.
final plans. The plan view (straight down from • Roads, gutters, swales, and other
~ above) is the most commonly used projection in physical features.
the design development stage. Secrion-elevations • Existing property improvements (e.g.,
or cross-sections are also useful to show the verti- homes and otherbuildings) and utiliries
~ cal arrangement of the streambank. including septic drainfields.
Final designs are prepared for the people who • Temporary construction staging area
actual ly install the project. These should clearly for material stockpiling and equipment
~ describe the exact sizes, shapes, quantities, types, storage.
and locations of all project elements. This infdr- • Top and toe of bank and water levels
mation is used to prepare bids, as well as in the (ordinary high water and design flows).
r actual construction process. The drawings should • Proposed areas of cut and fill.
~ Design Guidelines 727
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7-28 Design Guidelines ~
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~ o
Lo
~ -p
_
~ ~ ~
~ p t
~ Design Guidelines 7-29
Figure 7.18 Examples of syrnbols for plans and specifioolions.
~
,
~
Evergreen trees Plant groups ~
~
.
000 ~ . ~
~
Deciduous trees
Rocks ~
'
. ' ~
. , . .
. ~ oc: . .
. ~
Evergreen shrubs Shrubs ,
. ~
ONE ~
ACRE
0 100 200 300 ~
Scale and north arrow North arrows ~
7-30 Design Guidelines ~
• Existing trees and major plant materials
, with clear indicadon of whether each item
is to remain or be removed.
• Configuration of the design soludon around
~ existing (remaining) trees and other
vegetation.
• The zone around existing trees to be
' protected during construction.
• Areas of bank failures and extent of
proposed design.
' • Sources of plant materials.
• Plant names and sizes.
, • Location of temporary irrigation systems if
applicable.
• Power and water source and point of
~ connection if applicable.
• Name and phone number of contact person
representing the project sponsor.
~ • Any special conditions unique to the site.
~
~
' .
'
~
~ .
~ .
~
' Desigrr Guidelines 7-31
1
RECOMMENDED REFERENCES FOR
ADDITIONAL INFORMATION '
'
Gray, D.H. and A.T. Leiser. 1982. Biotechnical
Slope Protection and Erosion Control. Van ,
Nostrand Reinhold Company. New York,
N.Y:
Lagasse, P.F., J.D. Schall, F. Johnson, E.V. ,
Richardson, J.R. Richardson, and F.
Char►g. 1991. Stream Stability at Highway ~
Structures. Pub. No. FHWA-IP-90-014. Hydraulic Engineering Circular No. 20.
Federal Highway Administration. ~
Richardson, E.V., L.J. Harrison, and S.R. Davis.
1991. Evaluating Scour at Bridges. ~
Hydraulic Engineering Circular No. 18.
Federal Highway Administration.
Richardson, E.V., D.B. Simons, and P.Y. Julien. ~
1990. Highways in the River Environment. ,
Federal Highway Administration.
Schiechtl, H. 1980. Bioengineering for land
reclamadon and conservation. University ~
of Alberta Press. Edmonton.
Simons, Li and Associates. 1982. Engineering '
Analysis of Fluvial Systems. Fort Collins,
Colo. r
~
~
. ~
~
~
7-32 Design Guidelines '
~ L
~ CHAPTER 8
CONSTRUCTION PROCEDURES
~ -
The success of streambank protection and sta- ing requirements of the various plant species. To
bilization projects hinges on selecting appropriate attain project quality control, site supervisors
r methods, functional design, and on-site supervi- should ensure that the following tasks are com-
sion during construction by experienced person- pleted.
nel. Proper installation and quality control is criti- Prior to start of construction:
' cal to project success. This chapter describes con-
struction procedures and practices for bank stabi- • Contact the construction superintendent or
, lization projects to help ensure that project objec- crew foreman and arrange for a visit of the
tives are met. project site. Discuss each aspect of the
project and construction area work limits
~ with contractor. Review erosion and
8.1 GENERAL CONSTRUCTION sediment control requirements with
PIANNING contractor.
' • Obtain copies of needed plans, permits and
easements. All permits must be available
8.1.1 CONSTRUCTION SUPERVISION for review on the project site.
~ • Schedule and hold a pre-construction
Because many general contractors have little conference with inspectors responsible for
knowledge and experience with vegetative meth- pernut compliance. All contractors should
' ods, it is important to have experienced personnel also attend this meeting.
on-site for construction management. The basic • Contact and inform property owners in the
duty ofthe construction manager is to ensure that projectareaoftheupcomingproject. Secure
~ project specifications for handling, preparing and construction access where needed.
installing plant and other materials are followed, • Contact a utility locadon service to identify
and that the specified structures are constructed as underground utilities and mark the location
' designed. Supervisor(s) should be on site every in the field. .
day to resolve problems with materials, necessary • Delineate areas within the project site that
~ design changes, and other unforseen difficulties. require special attention.
They should also keep detailed records about • Identify vegetation to be preserved on the
materials used, costs, work performed daily by constniction site, and specify preservation
, each crew, percent project completion, and adher- methods. Prevent grade changes (either
ence to schedule. These records provide data on addition or removal of soil) within the
the quantities of material used and work per- driplines of trees to be preserved.
~ formed, difficulties encountered, and other impor- • Erect baniers around areas to be protected,
tant information for designing and estimating costs vegetation to be salvaged, and the driplines
of future projects. Post-project monitoring records of trees to be saved to prevent operation of
' should also include cost of and time required for heavy equipment in these areas.
monitoring, replacement of dead plants, and other • When vegetative methods are specified,
necessary maintenance. verify location and condition of source sites
~ Qualifications for supervisory personnel for harvesting plant materials.
should include experience with installing the speci- • Arrange for and implement construction
fied material and structures, including vegetative staking.
' methods, knowledge of proper handling and plant-
, Construction Procedures 8-1
•4 ~
• Ensure that construction materials (e.g., • Ensure correct placement and orientation
soil, vegetation, rock) meet project specifica- of cuttings, stakes, and branches in '
tions. vegetative methods.
• Verify that designs match actual ground • Ensure all materials delivered to the site
conditions. (soil, plants, rock) are of acceptable quality. ~
• Ensure that soil compaction occurs
At the start of construction: according to specification. '
• If specified, make sure that fertilizer
• Check the initial site preparadon (i.e. grading application and soil conditioning occurs.
and shaping) forconsistency with the project • Ensure that necessary staking, pruning and '
plans. cutting of vegetation occurs as specified.
• Verify the layout of each specified
stabilization method. '
8.1.2 MINIMIZING SITE DISTURBANCES
During construction: DURING CONSTRUCTION • Contact regulatory agencies as needed to In general, the less disturbance to the natural ~
facilitate required site inspecdons. system, the greater the environmental benefits.
• Coordinate the delivery (timing) of various Thus, disturbance of the stream/river and its ripar- ~
materials such as rock, vegetation and soil. ian corridor should be minimized during construc-
This material should be delivered in proper tion. Construction damages can be limited by:
amounts and sequence to avoid construction ~
delays or degradation of vegetation. • Installing erosion control measures as early
• Stockpile construction materials in proper as possible to minimize damages from
amounts and sequence in areas close to the sedimentation. ,
work area. Most construction sites have • Using small equipment and hand labor
limited working space and staging areas, whenever feasible.
most of which may lie at the edge of a • Limiting site access to as few locations as ~
streambank. These azeas need to be clear possible.
for equipment to operate and to avoid • Locating staging areas away from all ~
construction delays and waste in moving or sensitive areas and their buffers.
driving over construction materials. • Avoiding construction during critical times
• Ensure that the location and dimensions of such as spawning or nesting periods. ~
specified excavations are as specified. • Minimizing or avoiding extensive grading
• When harvesting, handling and preparing and earthwork in sensitive areas.
plant materials: • Retaining natural vegetation whenever ~
a. Ensure that fresh cuttings arrive at the possible.
project site each day and that unused • When vegetation must be removed, limiting
material is properly stored for use the the exposure of disturbed soil to the smallest ~
next day. practical area and time.
b. lnspect the storage area daily when it • For vegetation that will be saved, limiting
is in use to ensure that all unaccept- root exposure to the shortest possible time. ~
able plant material is removed from Remove and store in a temporary nursery or
the construction site and that only vi- holding area any existing woody vegetation
able materials are installed. that might be useful later in the project: ~
c. Ensure that invasive plant materials • Stockpiling and protecting topsoil removed
are not brought to the site. . during grading operations so that it can be
reused.
8_2 Construction Procedures ,
'
• Protecting sensirive areas exposed during 8.1.4 LABOR NEEDS
~ construction with temporary vegetation
and/or mulch. Vegetative stabilization methods are often la-
• Managing runoff and excess groundwater bor intensive. Two crews are needed for most
, to minimize erosion and slope failure. medium to large projects: one for harvesting plant
materials and one for installation. The number of
crew members will vary with the project. Two
' 8.1.3 SITE PREPARATION people per crew is generally adequate for small
projects. On small projects or where the plant
, Site preparation are those activities which oc- material is close by, one crew can both harvest and
cur immediately prior to the beginning of project install plant material as work progresses. On larger
construction. This includes such activities as iden- projects, crews should coordinate closely to pre-
, tifying and visibly marking clearing limits, install- vent having excess material on site which may
ing temporary erosion/sedimentation control mea- result in installation delays.
sures, placing construction fencing around areas Unskilled labor can be used if supervised by an •
~ to be protected, and installing construction drain- experienced crew leader. Because training re-
age if necessary. quirements are minimal, training can usually be
All earthwork activities (i.e., shaping and grad- accomplished on site in a few days. Some meth-
~ ing of banks, removal and disposal of excess ods, such as constructing fascines, can be com-
materials, stockpiling of soil and other activities) pleted by individuals who are physically or devel-
should occur in accordance with plan specifica- opmentally challenged, thus providing employ-
, tions and applicable regulations. Close coordina- ment opportunities for these diverse groups. Local
tion between the crews installing the erosion and and state conservation corps may also be a source
sediment controls and those preforming the of labor. Chamberlain (1986) reported excellent
' earthwork activities is vital for minimizing ad- success in revegetation projects along the Cedar
verse effects to water quality. River using labor recruited through the Washing-
Sites that are wet and poorly drained require ton State Conservation Corps. The Washington
~ extra preparation. At sites with extremely wet soil State Departments of Natural Resources and Fish-
conditions, it may be necessary to prevent losses eries have used correctional inmates on some
~ of both plants and equipment by providing load- projects (L. Cowan, Wash. Dept. Fish., per. comm.,
bearing mats from where equipment can be safely 1992).
operated. If the moisture is from surface water or
~ shallow groundwater, a French drain or other
drain may be needed to intercept the flow. In some 8.2 CONSTRUCTION PLANNING
cases, drains can be incorporated in the structure. FOR VEGETATIVE METHODS
, A geotechnical expert should be consulted if drain-
age problems exist.
If needed, the physical properties of the soil 8.2.1 ACQUISITION OF PLANT MATERIAL
~ can sometimes be altered by adding organic mate-
rial such as commercial compost, sand, silt, or clay
and mechanical mixing. Adding sand to wet clay Live Cuttings
' soils can be extremely difficult as the clay portions
often stick together rather than mixing. Although Live cuttings are normally collected from ex-
frequently recommended, this process is seldom isting, healthy, native vegetation. Local native
, successful in improving soil conditions. plants aze generally resistant to disease and are
. better adapted to local conditions than plants from
distant sources. Careful observations of donor
' material are required to prevent the introduction of
, Construction Prxedures 8-3
w
. Table 8.1 Relafive vdume of plant cuttings required for various vegektive methods. L
~
VEGETATIVE SYSTEM VOLUME OF MATERIAt
REQUIRED ~
Cuttings (Slips) Small
Rooted Cumngs Small '
Fascines Moderate
Live Cribwall Moderate
live Staking Moderate to large '
Brush Layer Very Large
Brush Mattress Very large ~
insect infested cuttings into the project area. The -familiaz with the area and with local plants. Utility i
willow bore (Cryptorhynchus lapathi), for ex- maintenance crews also frequently know where A
ample, is endemic in northwest willows. This large stands of suitable plants can be found. For
insect bores into the heartwood of the willow, projects such as brush mattresses or fascines, ~
killing the plant. storm water retention/detention ponds, utility
Plant material may be found anywhere from a rights-of-way, or similar managed areas may pro-
few feet to upwards of 50 miles from the project vide large amounts of vegetation at little or no cost ,
site. Naturally, the further the harvesting source is as the vegetation at these sites is periodically cut
from the project site, the more costly the operation. and removed by maintenance crews. ,
Longer hauling distances will also require more Because a harvest site may be needed again for
project coordination. Advanced planning may pro- future projects, it should be managed carefully and
vide a suitable plant source near the project site, left as healthy, clean, and tidy as possible. Lazge, ~
reducing collection costs as well as transport time unused material may be cut into manageable lengths
and plant mortality between source and project. for firewood, left in piles for wildlife cover, or
Local regulations on collecting plant materials scattered around for ground cover and to promote ~
should be reviewed before harvest operations be- decomposition. Unused material should not be left
gin. Some regulations, such as the King County in a condition that could encourage fires or create
Sensitive Areas Ordinance, restrict the collection other safety concerns. Diseased plant material ~
of plant material from riparian buffer zones and should be destroyed by burning.
other sensitive areas. Several alternative sites may Equipment that will result in the cleanest cut •
be needed to obtain the necessary quantities of (chainsaws, brush saws, bush axes, loppers, and ,
material. pruners) are recommended for cutting living plant
The source site must contain plant species that material. Vegetation should be cut cleanly at a 40
will propagate easily from cuttings. For best re- to 50 degree angle, eight to ten inches above the ~
sults, woody vegetation should consist of several ground if the whole plant is being used. This
different species. It is important to properly iden- assures that the source sites will regenerate rapidly
tify the species of woody vegetation that is to be and in a healthy manner. At some sites such as ~
used to ensure that adequate amounts of material detention ponds, the entire site may be cut. At
will be available. Dickerson (1992) describes rela- other sites, cutting must be done with care to
tive volumes of material needed for some vegeta- prevent serious degradation orenvironmental dam- ~
tive methods (Table 8.1). age of the harvest site.
Effective searches for suitable sources of ma- ,
terials can be completed from the air by someone
8-4 Construction Procedures ~
Rooted stock large amounts of rooted stock will be needed, as it
, allows ample time to produce good quality stock.
Nursery stock should be ordered well in ad- The commercial availability of rooted stock
vance of planting dates to ensure sufficient quan- varies seasonally as do the species and manner in
, tity and quality of the desired species. Because which they are available. During the wintermonths,
there is still a relatively small demand for native bare-root, single-tubed or balled and burlapped
' plant stock, only limited stock is available each plants are generally available and less expensive.
year. For large projects with sufficient lead time, After April, most nurseries put plants into contain-
contract growing can eliminate this problem by ers, though some nurseries will provide field plants
, starting cuttings and seeds anywhere from a few on demand. '
weeks to several months or even years in advance. The choice of stock type used (balled and If the desired plant species are not available, burlapped, bare root, containerized, cuttings or
' carefully review plant substitutions suggested by live stakes, rooted cuttings, seed mixes) will be
nursery staff. The definition of "native plant" defined by the anticipated site conditions. These
varies widely among horticulture, landscaping, include river characteristics (e.g., freyuency and
, and nursery professionals. Often, nursery stock duration of inundation), soil conditions, control of
includes species that simply grow well in the competing vegetation, and the type of structure to
region or is related to the specified native species. be installed. If competition from grasses or shrubs
~ There are numerous commercial sources of may be a problem, larger plants or cuttings should
plants and plant information. Infonet (1992) pro- be used:
duces a monthly listing of stock availability, prices, The quality of the plant material is very impor-
' and size for many nurseries in the Pacific North- tant forlong-term survival. If possible, orderplants
west. Shank (1991) provides a list of Pacific North- grown from seed collected from the same geo-
west nurseries that produce native species. graphic area and elevr.:ion as the planting site.
' Baumgartner et al. (1991) provide information on Most growers have this information available.
sources, selection, planting, and care of trees. Often, these plants will be better adapted to cli-
~ Table 8.2 lists local growers of native plants. matic conditions of the site than plants from more
Ideally, the best nursery stock for river projects is distant regions.
from local nurseries, i.e., those located within the
' same major drainage basin as the project site.
8.2.3 INSTALLATION TIMING FOR
VEGETATIVE METHODS
~ 8.2.2 FACTORS AFFECTING PLANT
COSTS For maximum success, streambank stabiliza-
tion projects should be installed while plants are
' The cost of plant material reflects the time and dormant (Schiechtl 1980; Adams 1982; Baum-
effort required to produce the plant. As such, small gartner et al. 1991). Once buds break and leaves
plants are usually less expensive than larger plants begin to expand, plant survival rates decrease
' of the same species. Fast-growing, easily propa- markedly. Fully-leafed plants may have survival
gated, relatively pest-fr.ee species tend to be less rates of five to ten percent or less. Installations
expensive and more readily available. Because the should coincide with cool, moist but not exces-
' cost per plant increases with small production sively wet weather in either spring (late February
quantities, even an easily propagated species can to April) or fall (October to mid-December). If
be expensive if there is limited demand. high flows are not anticipated against a recon-
~ Some nurseries may offer discounts for large structed bank, fall is the best time to plant because
orders or contract-produced material on a case-by- substantial root growth can occur during the win-
case basis. Contract growing is recommended if ter. Because root growth occurs any time the soil
' is not frozen, fall planting allows trees, shrubs, and
~ Construction Procedures 8-S
cuttings to establish better root methods prior to the difficulty in working wet soil and also because
summerdroughts than does spring planting. Spring of excessive soil compaction can occur. '
plantings with supplemental irrigation are recom- While vegetative methods are most effective
mended if site conditions are such that a fall when installed during late fall to early spring, this
installation may be removed by high flows. Unless may not coincide with the construction window '
irrigation is provided, summer installations can be for working in King County streams. The con-
difficult because of drought stresses that occur struction window refers to the period of the year '
when plants are cut or transplanted. While accept- when the Washington Departments of Fisheries
able, winter is generally not preferred because of and Wildlife allow instream construction activi-
ties. Because it is defined by the presence of '
Table 8.2. List of local growen and nurseries providing naiive species in and nearby King County.(Compiled '
from Shank 1991 and Baumgariner et cl. 1991.)
Abundant Life Seed Foundation Port Townsend 385-5660 ,
Borfod's Hardy Ferns Bothell 483-0205
Cascade Conifers Olympia 754-6827 ~
Colvos Creek Farm Seattle 441-1509
Fancy Fronds Seattle 284-5332
Fir Run Nursery Puyallup 848,4731 '
Frosry Hollow Nursery langley 221-2332
Furney's Nursery Des Moines 624-0634
Hood Canal Nurseries Port Gamble 297-7555 ,
IFA Nurseries - Nisqually Olympia 456-5669
1. Hofert Forest Nursery Olympia 786-6300
King County Conservation District Renton 226-4867 ~
Lawyer Nursery Olympia 456-1839
Morning Glory Farms Stanwood 6294831 ,
Newstart Nursery Camano Island 629-3751
Pacific Natives & Ornamentals Bothell 483-8108
Pacific Wetland Nursery Kingston 297-7575 ~
Peninsula Gardens Wholesale Gig Harbor 851-81 15
Silvaseed Company Roy 843-2246
Storm Lake Growers Snohomish 7944842 ~
Sweetbriar Nursery Woodinville 82 1-2222
. Tissues & Liners Woodinville 885-5050
Warm Beach Nursery Stanwood 652-5833 ,
Watershed Garden Works Olalla 857-2785
Webster Forest Nursery: DNR Olympia 753-5305
Wetlands Northwest Graham 846-2774 ~
Weyerhaeuser Rochester 273-5527
Weyerhaeuser Tacoma 9242547
rtment of Public Works does not endorse any of the above businesses or their '
The King County Depa
products. This list is provided to the reader only as o general service in locating materials described in
this document. '
8-6 Construction Procedures ~
spawning salmonids or incubating eggs, the con- Branch bundles should be placed on the trans-
~ struction window varies from stream to stream. port vehicles in an orderly fashion to prevent
Planting times also vary with weather conditions, damage and facilitate handling. The material should
elevation, and other site conditions such as soil be covered with a tarpaulin during transportation
' moisture. to prevent additional stress from drying. Damp
Several options are available for construction burlap draped over plant materials or placing the
that can not coincide with the construction win- cuttings in moist sand will provide additional
~ dow and yet must occur within the channel. On humidity and reduce drying of cut ends. While
small sites it may be feasible to isolate the con- latex paint is often recommended to seal, and,
struction activity from flowing water with pile sometimes can be helpful in identifying the up-
, barriers, sand bags, coffer dams, or other means. right end of live stakes, its use can be very messy
At other sites, phased construction may be fea- and does not seem to appreciably increase plant
' sible. For example, the construction of the struc- survival.
tural component, which is most disruptive to the Plant material should be harvested and deliv-
stream, could be completed during the construc- ered to the project site as quickly as possible,
, tion window, with the installation of vegetative especially on warm (more than 50° F), windy, or
system occurring during the following dormant low-humidity days. For maximum survival, cut
season. Phased construction may increase overall plant material should arrive at the job site within
~ project costs, especially if equipment has to be eight hours of cutting. Vegetation for live stakes or
moved. Under certain conditions, however, it may other similar use should be used the same day that
be the most practical or only option available. it was cut and trimmed. If the air temperature is
' Another alternative is to use rooted plants 50°F or higher, all live materials should be in-
instead of live cuttings so that vegetative elements stalled on the day they are cut. Although not
of the project can be installed during the construc- optimum, material not installed on the day it was
' tion window. This option is generally more expen- cut can be installed later if the air temperature is
sive as nursery stock must be purchased or grown. less than 50°F. Because live plant material often
In some cases, the construction window can be deteriorates and is less effective when held for
' altered as much as a week by harvesting materials long periods, all fresh cut plant materials should be
at higher elevations where they have either not used within two days after cutting unless refriger-
~ broken dormancy (in the spring) or have entered ated.
dormancy (in the fall). Generally the differences Protect all plant material from drying by stor-
in elevation should not exceed 1,000 feet, nor ing it in shady, moist areas, placing it in fresh water
' should plants be imported across major watershed or in cool storage if it must be stored for several
boundaries. This helps protect the genetic integ- days. Outside storage locations should be continu-
rity of local plant populations and reduces the ally shaded and protected from the wind. Water
' chance of introducing disease organisms into used for keeping cuttings or rooted material moist
healthy populations. should be free of substances toxic to the plants
such as petroleum products or excessive amounts
~ of nutrients.
8.2.4 HANDLING, DELIVERY AND Plant roots must not be allowed to dry. Expo-
STORAGE OF PLANT MATERIALS sure of root systems to drying agents such as sun
' or wind is the cause of many planring failures.
Live branch cuttings should be bound securely Desiccation of roots results in the plants effec-
into bundles at the collection site for easy handling tively being unrooted cuttings when planted. Low
~ and for protection during transport. During bun- temperatures and high humidity, preferably re-
dling, the growing tips should be oriented in the frigerated storage, aze ideal storage conditions. If
same direction with side branches and limbs kept cool storage is not available or if planting is
' intact. delayed, plants should be "heeled in" until they
, Construction Procedures 8 7
can be planted. This practice consists of loosely ing earthmoving and prior to planting. The tillage '
planting the vegetation (whether containerized, can be accomplished using a bulldozer equipped
balled and burlapped, or bare root stock) in a with either subsoilers, brush blades or rock npper
temporary location in the shade to prevent desic- teeth attachments. It is necessary to loosen the soil '
cation of or heat damage to the roots. to a depth of at least 12 and preferably 24 inches for
Even container plants should be kept in the satisfactory results.
shade to reduce stress. The soil in a black plastic Soil backfill should be free of any material or '
container can exceed 120°F and remain above substance which could be harmful to plant growth.
100°F for several hours. Temperatures of 104°F Gravel is not a suitable material for use as fill
for only four hours is lethal to root tips of most around live plant materials, nor should it be placed '
plants. If plants begin to wilt and the root ball in the bottom of planting holes to improve drain-
appears very dry, set the plant in a pail filled with . age. Saturated soils that otherwise meet fill re-
water and allow it to soak the water up slowly. quirements should not be considered suitable fill '
While water should not completely cover the root material until dried to an acceptable moisture
ball, there should be sufficient water to thoroughly content. Soil having an appropriate moisture con-
wet the entire ball. Tree seedlings (trees less than tent, when formed into a ball, should crumble ~
one year old) should not be stored with their roots when pressed between the thumb and fingers. If
submerged in water (Pitkin and Burlison 1982). the ball sticks together, the soil may be too wet to
Bareroot trees and shrubs, however, may be soaked be properly worked. Heavy clays should not be ~
for one to two hours prior to planting (Maleike and mixed with sand to improve texture as this usually
Hummel 1988). Do not saturate or submerge the results in irregular pockets of sand and clay rather
plant for more than two hours. than a uniform mixture. If the clay content of a soil '
When using rooted stock, it is advisable to is very high, it may need to be replaced with more
storethis material somewhere otherthan the project suitable fill. While the fill does not need to be ~
site where it may be prone to vandalism or theft at organic topsoil, it must be capable of supporting
night. Also, in areas of heavy traffic, barriers plant growth.
should be erected to keep plants from being dam- Some perennial grasses such as reed canary
aged (trampled or uprooted). grass may compete with installed vegetarion for ~
water and nutrients. If present, this vegetation
should be removed or controlled prior to planting. ~
8.2.5 GENERAL INSTALLATION Preliminary mechanical control (tilling or cutting)
PROCEDURES FOR PLANT should be used to reduce initial competition and
MATERIALS allow easier placement and planting of selected ~
species. While chemical control may be required
In all situations where vegetative methods are in some situations, many herbicides are highly
used, it is critical to provide good contact between toxic to aquatic organisms. Extreme care is re- ~
soil and plant material (cuttings, seed, or rooted quired if these chemicals aze used. In any case; it
stock) for root development. All fill around live is desirable to limit the use of any pesticide near
plant cuttings should be compacted by foot or by water bodies to reduce the chance of water con- ~
machine to densities similar to that of the sur- tamination.
rounding natural soil, taking care not to damage Mechanical methods to control undesired veg-
roots in the process. The soil around plants should etation include disking, harrowing, and scalping. '
be free of large air pockets. On uneven ground or steep slopes with dense
Undesirable soil compaction during the plant- ground cover where shrubs and trees are desired,
ing phase may be prevented or reduced by limiting or in areas where large vegetation is being saved, ~
operation of machinery on wet soil. Where com- scalping may be the most suitable. It requires
paction is unavoidable or soil is already com- removal of the above-ground portion of compet- pacted, tillage can alleviate the condition follow- ing vegetation (root removal enhances effective- '
8_8 Construction Procedures ~
' L
ness) from an area about 30 inches in diameter. anticipated scour line, as described in the general
~ The plant, cutting, or live stake is then placed in the design considerations listed in Chapter 7. Failure
center of the scalped area. to observe this precaution is a common cause of
, Follow-up control in succeeding seasons may failure:
be required (Pitkin and Burlison 1982). If fertiliz- When planning for tce excavations, permit
ers are to be used where competition from weeds provisions and construction may require separat-
, may be a problem, use fertilizer tablets or spikes ing the work area from the main flow. The con-
that are placed below the soil surface, (e.g., worked struction of the toe key usually involves diverting
into the backfill or root ball) or slow-release fertil- the flow, removing fish (if present) from the area
~ izers to avoid encouraging excessive growth of to be dewatered to prevent stranding, dewatering
weeds. of the construction area, and implementing sedi-
ment control measures. Depending on the size of
~ stream and flow conditions during construction, a
8.3 INSTALLATION PROCEDURES simple diversion such as a small instream dike
FOR DIFFERENT METHODS constructed of sandbags may be sufficient to sepa-
, rate the work area from the main flow. In larger
As outlined in Chapter 7, there are three gen- rivers, where flow depths are significant, installa-
eral types of bank stabilization methods: rock, tion of temporary cofferdams using sheet piling
' vegetative, and integrated methods. General pro- driven into the river bottom may be necessary.
cedures for installing each of these methods will Because the methods mentioned above will
be discussed in the following sections. Schiechtl not completely eliminate seepage into the con-
~ (1980), Gray and Leiser (1982) and Coppin and struction area, dewatering may be necessary. Water
Richards (1990) describe installation of these from dewatering operations should be pumped to
methods in detail. vegetated upland areas c: settling ponds to remove
~ sediment before discharging it back to the receiv-
ing water. Erosion and sediment control systems
8.3.1 ROCK PROTECTION METHODS should be designed and installed as part of the
~ streamflow diversion and dewatering systems.
Successful installation of rock methods relies For construction, it is usually most practical to
' mostly on appropriate equipment selection and use equipment stationed on the top of the bank to
operation, and the experience of the personnel reach down, excavate, and place the rock. This
installing the system. The specifics of selecting depends on the bank height and having a nght-of-
~ equipment, other than having equipment large way or an access road. If the bank is higher than the
enough to handle the specified rock, is not dis- equipment reach length, construction of a bench at
cussed herein. the ordinary high water line facilitates equipment
' As with other methods, all construction must access. In extreme cases, where right-of-way and
adhere to the pernutting requirements described bank height constraints combine to make con-
elsewhere in this document. Instream construction struction from above not feasible, equipment such
~ should take place during low-flow conditions, and as a"spider hce" can "walk" up the stream and
during a time of minimal fish usage as prescribed perform the work from within the channel. If this
by Departments of Fisheries and Wildlife through method is considered, it is very important to be
' their Hydraulic Project Approval process. aware of fish usage of the project area during the
Construction of the rock toe key can be diffi- construction period. In larger rivers, where flow
cult, particularly in large rivers where flow depths depths and velocities are suitable, performing con-
' may be significant. Because the toe is keyed in, not struction from a barge may provide another alter-
just end-dumped, excavation of the existing lower native.
streambank may be necessary. The bottom of this Prior to placing riprap, the banks should be
, toe should be keyed into the channel below the graded to a 2H:1 V: side slope or flatter. Depending
' Construction Procedures 8-9
,
on its size, riprap may be either hand-placed, end- Rooted Stock ~
dumped, or placed by deirick crane. Most riprap is
placed on a filter blanket of smaller sized, graded Rooted matenal may be planted in slits or
material (gravels and spalls) that is typically eight planting holes, depending on the size of the root '
inches thick. The area to be covered with a filter mass. Slit planting involves inserting a spade into
blanket should be reasonably smooth. An even the soil and rocking it forward to create a space.
thickness of filter material should be placed on the The plant is placed in this space and the soil is then ~
prepared surface. Care must be exercised when tamped back around the roots.
placing the riprap to ensure that the blanket is not Planting holes for rooted stock should be as
ruptured or displaced. The riprap should extend up deep as and twice as wide as the root mass to ~
the bank far enough to give adequate protection promote the lateral spread of roots (Figure 8.1 a, b,
against scour by debris, flowing water, or wave and c). If the soil is severely compacted, break up
action. more soil under the root ball to encourage root ~
penetration; do not, however, add soil amend-
ments.
.8.3.2 VEGETATIVE METHODS Nursery stock should be planted from 0.5 inch ~
deeper to 2 inches higher than it grew in the
nursery (Pitkin and Burlison 1982, Maleike and
Herbaceous Ground Cover Hummel 1988). The root crown should be at or ,
slightly above the level of the surrounding soil.
Numerous methods exist for establishing turf. Planting with the root crown too low, especially in
These include laying sod (e.g., "instant lawn"), soil that is apt to settle with time, can result in '
hay and straw seeding, broadcast seeding, hydro- crown rot from excess moisture. Partially loosen
and dry seeding, and foam seeding. While sod, hay rootballs and mix the planting medium with the ~
and straw, and broadcast methods are often in- native soil to reduce soil interfaces that can impede
stalled with hand labor; specialized equipment is water movement and root growth. Circling roots
required for hydro-, dry, and foam seeding. Seeds should be straightened or cut before planting. ~
should be sown at no more than 20 pounds per acre The planting hole should be backfilled with
to prevent depleting moisture and nutrients in poor native soil, NOT topsoil. The soil loosened from
soil (Sears and Mason 1973). This, however, may the root ball should be mixed with the native ,
vary with local conditions. Drills are preferable to backfill material. Adding large amounts of or-
broadcast seeding. The California Department of ganic material, topsoil, or soil of a texture substan-
Water Resources (1967) reports that almost all tially different from the native soil does not im- ~
grass test plots sown in spring did better than those prove plant growth and may be detrimental. Large
sown in the fall. Whatever the method, seed-to- differences between planting hole soil and sur-
soil contact is essential for germination and seed- rounding soil result in difficulties in moisture
~
ling establishment. If seed gernunation is poor, regulation. For example, if the native soil is heavY
reseed thin areas as soon as possible to prevent or somewhat compacted (as many northwest soils
erosion. are) and the planting hole is backfilled with loamy ~
Streambanks to be protected with turf should soil, the planting hole functions much like a large
be sloped to a stable grade, normally 2H:1 V on clay pot and frequently drowns the plant during
outside meander bends (concave bank) and 3H:1 V wet weather. During dry weather, the plant is '
or less in straight reaches. If right-of-way space is subjected to excessive drought because of lower
available, compound bank designs that include water holding capacity of soil in the planting hole.
walkways orrecreational facilities within the berm The backfilled material should be gently ,
area are ideally suited for turf. tamped around the root ball; this can be achieved
by watering the soil while backfilling the planting '
hole. A"tree well" or watering basin may be
8-10 Construction Procedures '
Figure 8.1a Installaiion of rooled siock--single-siem tree.
,
,
~
t
'
~
,
~ '/z in. soft rubber nose tie with
w/ 2-12 ga. wires per tie
Stakes
`r 2 in. x 2 in. x 8 ft. rough cut
o stakes
2 in. bar{c mulch
~
Mound to hold water
, ' ' r= ~ • i / ~ _
Peel back and remove top
' of burlap
•X' :t;•:
~ ,:`i'.•'`' ~~•::•f,Native soil backfill .
i ~ •'•D° ' ~ ~i
~~~~~~cC:l;~-'•j ~ -
1.5-2.0 times
' greater than rootball
Figure 8.16 Installation of rooted siock-shnub.
%
' 2 in. bark mulch
~ Mound to hold water -
uRemove top'h of burlap ti\ ~~`I
Native soil backfill
~ 111- i =
1.5-2.0 times greater than rootball
'
,
, Construction Procedures 8- > >
,
Figure 8.1 c Installalion of rooled siock-muMi-stem tree.
~
'
~
.
. ~
Ik in. soft rubber nose tie ~
w/ 2-12 ga. wires per tie
2 in. x 2 in. x 8 ft. rough cut ~
stakes
~ ~ • ~ 2 in. bark mulch ,
~
Mound to hold water
Peel back & remove top
L , . ~ ~ _ 'h of burlap
!I'!~. p ,
Native soil backfill
o - - II~~• I ~ ~ '
~ • ° ° ' ~ I ~
1
1.5-2.0 times
greater than rootball ~
'
~
'
8-12 Constniction Procedures '
'
formed azound the edge of the planting hole. This roots. Plants with viral or fungal diseases or insect
' can be especially important on slopes that might infestations are a source of disease for entire
not intercept sufficient rainfall. The plant should plantings and should be removed from the site.
be well watered once at planting, then not again for Appendix D provides an example of plant quality
' at least one week unless signs of drought stress are specifications.
visible. This encourages roots to grow outward
from the planting hole. Roots that extend from the
, root ball (e.g., circling roots that can be straight- Live Stakes and Slips
ened) and the roots of bare-root stock should be
, surrounded by native soil. This speeds the accli- Cuttings for live stakes must be from a species
mation of the plant to the site and improves long- with large sturdy stems, one to two inches in
term survival. diameter. Slips (0.2 to 0.5 inch in diameter) can be .
~ . While soil amendments are typically not cut from any branch large enough to handle easily.
needed, slow-release fertilizers occasionally are In either case, the cuttings must be alive with side
beneficial. Regular commercial fertilizers and fresh branches removed and with the bark intact. The
' manure should not be used as they can cause basal ends should be cut cleanly at an angle for
severe damage to recent transplants. easy insertion into the soil; the top should be cut
Ensure that the roots are arranged in a natural square or blunt (Figure 8.2). Slips are most easily
' position, i.e., pointing generally down and away prepared by making each cut at an angle. Stems
from the root crown. Circling roots can lead to should be cut into two to three foot lengths for live
girdling and eventual death of the plant. Any stakes, one foot forslips. Larger diameter branches
' circling or badly kinked roots should be straight- may be cut longer. These cuttings should be kept
ened or removed. When the plant is at the desired moist after they aze cut and ideally installed the
height, fill around the roots with loose soil. Simply same day that they are nrepared. If it is necessary
, stepping gently (not putting full weight) on the soil to store cuttings, they should be protected from
a few inches from the trunk all the way around is dehydration (e.g., placed in moist peat in plastic
generally adequate to firm the soil. With balled bags) and either frozen or kept slighdy above
' and burlapped stock, it is essential to remove all freezing (Platts et al. 1987). Prior to planting,
wire, strings and twine to prevent girdling the frozen cuttings should be stored for two or three
' plant. If a synthetic burlap was used, it should also weeks at 41 °F to break dormancy.
be removed. Mulch may be needed around the To plant, tamp live stakes into the bank with a
plants to maintain moisture and moderate tem- dead blow hammer (i.e., a hammer with the head
~ peratures. Information on mulches is provided in filled with shot or sand). Live stakes should be
Chapter 6. installed with the upright end exposed (i.e., the end
It is not necessary to prune the top of plants that was up prior to being cut) and the butt end
' when they are transplanted. Studies have shown pushed into the soil. In firm soil, an iron bar may
that unpruned trees actually recover more quickly be needed to make the pilot hole. The diameter of
from transplant shock than pruned trees. It is the iron bar should be slightly smaller than the
~ beneficial, however, to remove dead or diseased cutting to ensure a snug fit. Slips are pushed into
branches and those that cross and rub against one the soil by hand. Live stakes should be placed at
another. If plants must be staked to prevent them right angles to the slope with four-fifths of the
' from toppling, remove the ties as soon as possible length inserted into the ground to prevent drying.
(usually after one year). Ties can also girdle trees, The soil should be firmly packed by foot around
and unstaked trees develop stronger, more flexible the cutting after it has been tamped into the ground.
~ trunks. Replacing any cuttings that split or break during
Quality control is important for project suc- tamping is optional, as some may survive if they
cess. Reject dead, obviously unhealthy plants and are not badly damaged. A plant loss of 30 to 50
' those with excessive broken branches or damaged
, Construction Procedures 8-13
'
Figure 8.2 Inslallation of live stakes shown wiih on opiional rock toe key.
,
. ~m• '
, • : . . : '
. : . . . .
' . . • . : . : . . ~
OHW v
~i~.•`;ti,;i•}:iv::~iy::F.titi;}{.:}lii.~:t:~i\(;:3::v:i{{i~:~•.+:~'?;<ir'i~:v:ii~Y•:'.f • • ~ .
Lj :;ti{yi;tii~: ti;i:}tr:::{yJ:i:iy%~'ti;{'•:v ' ~ • •
`i:}•`.'i}'L~iiiiij'+'?~':;:i;'::.::;?.:\}'v:ii~ii~'~'{i4':ii'i,h:..t:+:.;~:ivi.:` .
..:y}. ••;.,:k:? :'.,..~.!..;;\}~,?tt;>,,.,;.;>;, .
:;%i~`:~;;.;::•:~:''••: ~~~•::3c`;;~~: i:;:::;~:::.:,: .
,•:'t:i;:}:; L:;::::?;:;<:•'•:1:;~:..:::~:•'•: ~a, ~ a ;:'~+::,;:`y;,,•,.;; , ~
';`.:?>::~k;.;:•.::~2;:::.;..+,.;t.;;•:;~;o;;;::~~;;:;~;:~;:t;:,;•:.+:$.:;k:.:r .
~•':`••;i:::~•:,t::~k~::i:;;_;2.::;, 4:31:;1, ~
;.<,'~.r~.~~;~~'#:~;c...:.,.., .
.).;;';;i .:\y';2°`$`:£:,y,.+.}t?;;:tk~Y:•;;`:,:;.;.:.;: . .
v:'~•`,:.; 4i:: $}':.•:'.?i4~.'?:Ci\i } • '
•i"::: ~ i'i'iii:: ?i}i` •
• • • ~ ~ • . ~ Rock toe key
' • • • • • ~ ' (optional)
Channel bed
' , . . . . ~ SECTION A-A' '
A'
Live stakes placed ~ _ ~ ~ : • . '
in random pattern, • •
2-4 stakes per sq. yard~ .
• ~ • . ~ .
~ ~ ~ . ~ ~ . ~ ~ ~ ~ ~ : ~ ~ 1
. . ~ . . .
. . ~ .
~ . . . . . 1
. ~ ~ . . ~ . . . . . . . . . .
. . .
; ~ ~ .
~
KE
•
'•~;~:~::;~s:.:.` .
' . ;:::;~i~fi'•'.::;:;:`:
TA
IVE S
L
~.::~:x~.:.....
•:or:•:..: : ; ~
:>:•:.tY:•:. ::;:'Y
,
~ ~ :;`•;<:<::;•`:.::::;?::>:
. x {'•::~s~::,`~r:•y:::~.~: `:~;<:`~:::>;::?•'::r<:;;.
TAIL
:?k:iri:~>~~~~~
:;::i;•,'!!!;[i:.}1::iii:.}tr.:?i?: .Y....:: .
DE
ii4:::+ii. •
i
<; ~ ~ ~ ' . . . : : : : . . :
':..;;;~:''~'::<~:'<>s:::
.
:
. .
A ELEVATION ~
,
8-14 Construction Procedures '
' t
percent is common with this method (Schiechd downslope side of the bundles. Repeat the entire
' 1980; Christensen and Jacobovitch 1992) process at three to five foot intervals to the top of
The density of the installation ranges from two the bank.
tc four cuttings per square yard. Live stakes should Soil must be well worked into the bundles for
' be placed in a random to triangular configuration good rooting to occur and to prevent ditches from
with a spacing of two feet or greater. For slips, collecting water. Collected water can drown cut-
higher density (about 12 cuttings per square yard) tings and cause erosion by flowing along and
' at one foot spacing is recommended. across the slope (Gray and Leiser 19$2).
Gray and Leiser (1982) provide further infor-
mation on the installation of fascines.
, Fascines
, Fascines require long, straight branches; young Brush Mattresses
willow or dogwood 0.4 to two inches in diameter
is ideal for this method. Stems may be any length For this technique to be successful, it is essen-
, over three feet--the longer the better. The cuttings tial that the branches are in contact with the soil.
are prepared in bundles of at least five stems with The butt (i.e., the basal) ends of the branches
a minimum diameter of 0.5 inch tied together with should be covered so they can root and not dry out
~ the direction of the growing tips alternated ran- or be washed away. There are two methods for
domly (Figure 8.3). The number of stems varies protecting the branches: 1) placing the butt ends
with the size and kind of plant material. The into a shallow trench and covering the ends with
' bundles should be 8 to 10 inches in diameter. For soil; and 2) placing the branches in a shingle-like
ease of handling, bundle length typically varies manner and covering the mattress with a layer of
between 10 to 30 feet. Bundle lengths can be soil. If the length of the branches is not sufficient
, extended by interlacing the ends of bundles. Fascine to cover the entire length of the slope, the branches
bundles can be tied with string such as baling in the lower layer must overlap the upper layer by
twine or hemp. They should be snug but not so at least 12 inches (Schiechtl 1980). A slope for a
~ compressed that soil will not filter in among the brush mattress installation should be laid back to
twigs. Both live and dead stakes at least two feet a uniform grade of 1.511:1 V or flatter (Figure 8.4).
long are used to secure the fascines. Lay branches with butt ends in a shallow
' Beginning at OHW, dig a shallow trench one- trench with tips pointing upslope. To ensure root-
half to two-thirds the diameter of the bundle (six ing, the branch layer, 4 to 18 inches thick, should
inches deep and eight inches wide). To minimize lie smoothly against the bank. If additional protec- -
~ drying of the soil, trenching should not precede tion is desired, place a fascine in a trench on top of
laying of the bundles by more than one hour (Gray the basal ends of the branch mattress. To anchor
' and Leiser 1982). When placing the bundles, care the mattress, place live or dead stakes that slightly
must be taken to overlap (i.e., interlace) the ta- protrude above the brush layer over the face of the
pered ends of the bundles to ensure that the overall bank in a square or diamond pattern two to three
thickness is uniform. After placing the fascine into feet apart. Dead and live stakes are also used to
, the trench, drive the dead stakes directly through secure the fascine. Attach the wire (e.g., 20 gauge
the bundle. Extra stakes should be used where the electrical fencing) to the stakes and wire down the
~ bundles overlap. Leave the tops of the stakes flush mattress branches as close to the slope face as
with the installed bundle. Place and compact soil possible. Tighten the wire by tamping the stakes
along the sides of and into the bundles. fuRher into the bank. Cover the brush mattress
~ Stakes must be installed directly through the with a sufficient amount of soil to ensure good soil
fascine bundle to initially secure it from moving contact, leaving some buds and twigs exposed.
during flood events. Tamp the live stakes between Although wire has been specified for securing the
' the previously placed dead stakes, and on brushmattressestothebankface(Schiecht11980),
Construction Procedures g- ~ 5
'
'
Figure 8.3 Insiallafion oF fascine bundles. (AdapFed from Gray and Leiser 1982.)
~
'
,
1. Stekeon
ooMour.
Preparo wattl4ng: cigar-shaped bundles of live
brush with butts altemating, 8-10 in. diameter, fied
12-15 in. o.c. Species which root are prefened. , 2. Trench above stakes
Bundles may be 10-30 ft. in lenglh. • 1/2 to','3 of bundles.
3. Place bundles in trench.
,
• 4. Add stakes through and betow bundles.
NOTE: Installation starts at bottom ol the 5. Cover wattling with soil, tamp firmly. Wattling to be
denk end proceeds upsbpe, /o/bwing +l- Y3 above grade and 10-20% left exposed.
steps 1 through 5.
SECTION
,
. . . • . • ~ ~
Fascine bundles Live or dead stake • •
~ ' ' ' ~ . ' . ' • ' . ' • ~ ~ . . ~ 2-3 feet . '
_ „ -
-ILr
~ • ~ • _ ~ . . . ' . , ' . ~ • _ . . • ' . ' ~ • ~
. .'I • . . . ,
' . ' • ~ t3-5 feet 10-30 feet
• • ~ • ~ • ' , ' • • • •A~ . • • •
' . • . . . , ,
A~,..:....n~ v?v.:... . ..n•.~.:?i. ~'.:L}:.;:.:..-.•:..
' • .:.1'.~
. ..:...~v..::._::~w:•:.~:r..~..~.~:.~>.::::.... ......:vn.::•.~.: •::v}wr}+y~ 4%ii1.;;:[t;?i~i;i?h'
;....y
v'•...;.{'•::r~`::i:~i:y
. . .....v..... . •.v.~:.:v::.~:>i"...::..n::....:..ti..::...:. ...::..::4.:~.:~..... ~~'i?~::i~':
. . . •.....vv:::.'i: ...:.~:ti?i.:i::+.
r::::
.
t:~'.: :?¢iii.~ . . . ?v$'~':
..:.:~•::.i.:y:..
...:n: i.~ . ......:.~i: .
_:;;.x
1.. , . w:::: : •.1:.; ?i~iti'~
. ..;.•v:i.~.:..
......_::}hvi}v.~:: v::: vl::::::n:~:::::::}•::.:?:.::~•.:v.:i.~..:i::: . . . . ...v'~
~:•::•:;•C.`S. ~ . . . . .
•
, vr~%:~:`;~;i:.::.:r•x,.~*:
• •
• : .
. . :
. . . ~ ~ . . .
,.::.,•:.,•x•...;;:..~::'•:'•
. ,..•:x;;~
,
• • . .
: : : : . . : . : : > : : ; • < •
: ..::.:v.~:::...... . .....::....:.ii:C?i~::fti~i: :i
. ti .
~ : • .v::
. ..titi:.~:i:}:~}i.iwf.i:i•' ♦.v.. :.:::i4:Y. .:.~::•.i' i:iy,ti^ii•.
•..n. . v.:.~..v.:.:~ :v.:.~:,:....... ......,.:.v...v.+'yi{•.:}i:..,:. ?:;:'v.x} .}y.,....•:.
.
,.:..:,:..;.;.•:.~:t::.~::::a,~.. .
t~:.:'.;,,;•.,.,...:..:.;..:t>..•.
. ~ .
• . •::•i 4.vs, ...,L.
. • .
:.::;::•,:c'; . .:..•:.<•:.:.:::`:•:<t;•: . •,••e,*..}arr.+::::•:•: ~
.
..:,:;.;~..~::~:-:;•<~•;<::.
. .
.
. . ~
,-::.;..,:~U.,„.:.,,~,.:,.~:.~:;
~~;rr.y.;.:.:.:.:::>:;.:::::.»;:;::.~;::.~.:;.:::::::;>~::::<
. . . . ~ ~ . . . . . .
.:.:~3~M~!I1!!I~M,'.,.:.;.:.;.x;.~.;:o..... . .
• . . ~
.
~.::.:e.:..
' ..v.v..::.~:::::::.::ii:{:::.~.•:....::. .::...:~•:.~::.}v...:..~ ...::....:.....4....::....::...: h.v;~v~: .
: ::•.~i:l+i.:~•::::ii:::}Gii}i::i•:}?:c ::ii' ~x:: • . v.~i::::::?i> :.:i'r':::.i~•::.~::.;
....v.. Ji.}•.~i•.w::~.~~...... . ...:.~:.};:ii:tv:.v.~i::::::::v;•,•.
?n~:::...:::w.:~:..:.~:...... ...+v:.:.;.:::i•:v':i::y:•.:iw...... .a.. v:+<ii.i.i:?.~:v~ix•.itiii':::>iiw:.l•rs`.i::.v:i>..;..1:>`y;:l.v,3
...i... v . . •.:.:~..:"4<.~:.::i•:.~::.;.;~.~.~?•::.;....4..M1 \
v:..~:::ii:::}i}~:i0i4::~iY::}:ti.... •x::.~:n...
NOTE: Topsoil cover not shown. ELEVATION ~
'
8-16 Construction Procedures '
Figure 8.4 Inslollation of a brush mattress shown with an opiional Fascine and rock ice.
~ (Adapted from Gr+ay and leiser 1982.)
'
~ Slekes,
3 ft.
O.C. ~
/ Wire or ,
1 i 'We `°pe
~
, 2 x 4 in. or 2 x 2 in.
Live or dead stake,
notched for ~
rope /y
r
~ ( r Fascine
, Wire or jute rope • ~ (Optpml).
secured
to stakes Rock tce
' Bnish mattress ~ (optbnal)•
(min. 12 in. ~
,
thidc)
. .
. . . . . . ~ _ :
, 3 A.
. .
mm ,
. • • .
, Note• Topsoil covernot shown. ELEVATION
• s n. ' .
'
. SECTION DETAIL AREAOF
• ENLARGED
' SECTION .
DETAIL
Stakes driven on • •
3 tt. ceMerseach way.
Minimum length 3 ft. ' '
~ .
Fascine . •
(oPtanal) . . . . .
1 ~h : 1 minimum slope
QFIVV
• • .
' ` ~ . . •
• . . . • • . L~ ' ' Rock toe key
~ . . . , . . . . • • • (optionaq
' ~ , . • ' ' SECTION
1 .
1
' Construction Procedures 8-17
'
Figure 8.5 InsFallaiion of brush layers. (Adapted from Gray and leiser 1982.)
A' I
,
ECges o1 PoI
~
. Befae topeoil Atter topaoil
coveting covering
p PLAN VIEW '
,
o ,
Vertkal spadng varies
deperWerlt upon bank height t0' mlMmum
Typical spacing: '
Botlwn rowS 3-51e9t. o ' .
Middle rows S6 feet,
Top rows 8- 121eet. 'o
2 feet ~
'
minimxn SECTION MA'
'
jute or hemp rope, or coir fabric has also been used fill. Fill soil used between the layers of branches
successfully (A. Levesque, King Co. Pub. Wrks, must be material that can support plant growth. ~
pers. comm.). The live branches used for constructing brush
layers should be 20 to 25 percent longer (three foot
minimum length) than the depth of the terrace. The '
Brush Layers branch layer should be four to six inches thick. The
branches are placed in a random, crosswise pattern
Brush layers consist of embedding live bran- (not parallel to each other) so that the pieces are ,
ches or rooted stock on successive horizontal rows covered with soil as far as possible (Schiechtl
in the face of a slope (Figure 8.5). Beginning at 1980). The butt ends should angle down slightly OHW, terraces (two foot minimum depth) are dug into the slope, and the tips should prowde slightly ~
in the bank face either manually or with machin- beyond the face of the slope (Gray and Leiser
ery. The platform of the terrace should slope up at 1982). It is important not only to mix branches of
least 10 degrees to the outside so that branches can different species, but also branches of different '
root along their entire length (Schiechtl 1980). If ages and thicknesses (Schiechtl 1980). This pro-
constructed concurrently with a fill slope, the vides deeper penetration of the roots, and more
branches are layered between successive layers of variety in the above-surface growth. '
8-18 Construction Procedures '
1
' In fill slopes, the branches should be covered 8.3.3 INTEGRATED METHODS
with a minimum of 12 inches of soil. Vertical
spacing between brush layers will be dictated .by
' -the erosion potential of the bank (i.e., the soil type, Joint Planting
rainfall, water velocities, and length and steepness
of the cut or fill slope). It may be as little as three The thickness of the existing rock layer is a
' feet to more than nine feet (Gray and Leiser 1982). majorconsideration in applying this technique. To
On high banks, the layers should be spaced closer achieve successful roodng, live stakes must be
at the bottom of the bank and be spaced further driven through the rock voids and into the under-
' apart as one moves upslope (Gray and Leiser lying soil layer (Figure 8.6). The stakes must be
1982). alive, with side branches removed and with bark
Schiechtl (1980) and Gray and Leiser (1982) intact. The live cuttings should be sufficiently
' provide further discussion of the installation of long (up to four feet) for the base end of the stake
brush layers. to penetrate the soil (two feet if possible) in the
' .
Figure 8.6 Instollation of jant planting.
'
,
' Varies, depending
on gaps in riprap ~
Riprap
' .
Up to 48 in. long live stakes •
~ 1-2 in. diameter with two . . : ~ . : • : :
lateral buds above grade.
Bottom of stakes to be in ~ . . . . ~ • ' '
native soil.
' . • . '
OI 1 W - k \y<~'l~^•.i'M~ ~ • ~
;;£:};::`••;.•`•~:~"~+~~`~:;t`' ;;~.~.k,'x:x~c;~k;sc,il':; . . .
~:`•=.`r.`::`:`;~:,.:;:;x?:::•`.•:`4'.'`•;.:` {k.`';s':
:;;a,
%::i;ti }:'i':::::::{:;iLii::}$~:;'i:•ti:~;~:;:'{
: ;,i.} v~• ,
.
?~i}::.:'ti.r:i::::$}::`:tii:;.`i
v:1•:ii.:•.~titi:.:i:::;fii{:;:}`i`:}.;p\ . . •
ti'::i:;:•':iv;:;::::.1:
}?v. w: • . . . .
' `•?•\ti:: a.::i ::•tiL •.v.:
?~~;{:~;$'':},..ti:ii:ti: ;~:.i: h•: }:i4:ti ~[~}iii•''4iQ;:~'."+,y~'}
?:i.~:}_f?;. . . . ,P.}1:.~.•.i~:•
~1~ •.~:lti:::,>:;:;i:~ti~vLiti;~i\'•:{4:v::.•.•''.+;r':i.~'•:ti~{{~'~L• . • '
~~~%~,1•.,.'ct.e,~:•:::iy;$~:;';?;:<.~~;•'•:;\;~{:;'y:;ti:;:;,i:}:.:}.iiy2:i: , .
..t;......:...
: ~ ..~+;:>.:;:;:ti:.:::;` ~~=~`::`:::~::.:::'r's:;;'?`• '
' • Rock toe key
, Channel bed ~ • . • :
. . SECTION
,
' Construction Procedures 8-19
'
backfill or interstices. The basal ends should be exposed. If necessary, the exposed end can be
cleanly cut at an angle for easy insertion into the trimmed to reduce moisture loss from the stake. '
soil; the top should be cut flat. If construction of the rock system occurs dur-
Cuttings must be fresh and must be kept moist ing the dry season, it may be possible to drive live '
(in damp peat moss, sand, soil, or plastic bags) stakes between the rocks at a later date. If a portion
after they have been cut into appropriate lengths. of the backfill consists of small rock or gravel, the
They should be installed the same day they are cuttings should be of sufficient length to reach '
harvested. native soiL
Tamp the cutting into the bank using a dead
blow hammer (i.e., a hammer with the head filled ,
with shot or sand). In firm soil an iron bar may be Vegetated Geogrid
needed to make the pilot hole. The iron bar should
be slightly smaller than the diameter of the cutting Vegetated geogrids are very similar to brush '
to ensure a snug fit. If the rod is of slightly larger layers except that the fill soil in the alternating
diameter, backfill the hole with sand or other fine layers is wrapped in a natural geotextile material
soil around the stake. Where possible, the stakes (Figure 8.7). Vegetated geogrids can be installed ,
should be tamped in at right angles to the slope. over rock toe protection.
Tamp about 0.8 of the length of the stake into the Geogrids in smaller projects are generally '
ground beneath the riprap. To prevent desiccation, shaped by hand. To facilitate building larger, longer
it is important not to have a long length of stake geogrids, excavation equipment can be used to
. ,
Figure 8.7 Instollation of a vegetated geogrid shown with an optional rock roe key.
,
Geotextile fabric '
Live branches '
. ; • .
. . l . ~i: • i' '
'':~:;',•'St,2."r • : • !':{''fi • ~ , , • •
. hti , .Ni•'r . . :2:: .
~ ,
. Fill material : . .
r.:. y.. 10-150
<
0
4 Y .
. r.
. •'1'f + . . ' .
'.y. iF. .
. : -
. . 1 2 ft.
„ . .
OHW. . . "~L;~~:::,:>F:.,:.,::.:r, • Height
;:;:i:k+,'p;•ti?v{::i:iil:::$:::::ii:i;:;::{'.•;?{?:•',:yt':;' L::::>:;, :::::::::::::<:::<:<::~ <:>>::::::':::~:><:~-~~::::::>:::.:::.~;:;.:::::.;:<.::::::.;:..~:.:.:;::::. varies
. x;.:..
i:.:i:'i:Gi::;}::::?:'?:{Si::? . .
. .
6-8 in.
. • ' . . '
:.::::ti:::<~>::;;<:~:~>:::<:;::::;.;:;.:::::~ •
{<.~w.';;`:.>~';.•;. ;.:<»>::<::::>. . ,
;:''''~ii i•.LV ti l:1\;?:::}; :;?:i:. .
. - • . . . . . ~ Rock toe key
. . - • • ,
Channel bed : . ' •
SECTION '
8-20 Constnuction Procedures '
' . `
shape the geogrid; construction jigs and batter Backfill the lift with specified material (exca-
~ boards may also be used (Figure 8.8). The jigs, vated native soil, or specified soil mixture). Com-
which are constructed of angle iron, hold the batter pact the soil to create 1.0 to 2.0 foot lifts; maintain
boards that shape the face of the lift to match the a 10 to 15 degree backslope with each lift. Starting
f existing slope contours. Shorterbatterboards (three at the downstream end of the project site, flip the
to four feet long) and sufficient jigs will facilitate remaining geotextile material of the most down-
this process. After completing the lift, the jigs are stream strip over the backfill. After stretching the
, removed with a backhoe. geotextile so that it is snug, secure it by staking. If
Begin construction by excavating and shaping possible, stake the material into native ground. To
the bank to create a bench with a 10 to 15 degree complete the lift, work in an upstream direction
, backslope. Place at least six inches of fill material following this sequence of steps for each strip.
over the bench followed by a layer of live branch- Remove the batter boards and repeat the pro-
' es. The live branches should be 20 to 25 percent cess beginning with the next layer of branches.
longer than the depth of the bench (three foot The process continues until the'structure is at final,
minimum length). The branch layer should be four specified height. The geogrid structure does not
' to six inches thick. The branches are placed in always need to be built to the original bank height;
random, crosswise pattern (not parallel to each the upper bank may be completed with other
other) so that the individual pieces are covered systems.
~ with soil as far as possible (Schiechtl 1980). The There are several options for protecting and
butt ends should angle down slightly into the tying in the ends of the lifts. One method is to add
slope, and the tips should protrude slightly beyond additional strips at the ends of each lift. This strip
the face of the slope (Gray and Leiser 1982). It is is laid perpendicular to the lift strips. When posi-
important not only to mix branches of different tioning these extra strips, the upstream end strip is
species, but also branches of different age and laid first, and then covei:;d by subsequent lift strips
thicknesses (Schiecht11980). This provides deeper (i.e., the first lift strip is contained by the end strip).
~
e last stri
penetrarion of the roots, and more vanety in the Downstream, the end striP is th p to be
above surface growth. The brush is then covered positioned (i.e., contained within the last lift strip).
~ with a layer of topsoil and lightly compacted to Beginning with the downstream end strip, fold and
remove air pockets and work the soil in and around secure the strips in the sequence as described
the brush. Maintain a 10 to 15 degree backslope. If above for constructing the lifts. Another method is
, constructed during the dry season, thoroughly wet use leave extra material at the end points of the
each layer of branches and topsoil. lifts. This material is folded and staked using
Next, place the jigs and batter boards for the "hospital corners" to lap and tuck the material
1 face of the first wrapped lift. Lay pre-cut strips of snugly into place. Protecting the end points of the
geotextile on the bench. The geotextile strips should lifts can also be achieved by tying into existing
~ be slightly longer than two bench widths (i.e., two stable features or by placing rock or large woody
bench widths plus the height of the lift). Beginning debris.
at the upstream end of the project and working
~ downstream, lay the geotextile strips so that the
downstream strip overlaps the upstream strip by Live Cribwall
1.0 to 1.5 feet. The remainder of the material
~ (slightly more than half of the fabric) should be The following discussion is limited to simple
draped over the batter boards. cribwalls less than six feet in height. A engineer
Secure the geotextile strip by staking the rear knowledgeable with cribwall design should be
~ portion of the strip to the soil beneath it. Set at least consulted if constructing a larger or more complex
two rows of stakes. Commercial construction stakes structure.
12 to 24 inches in length work very well for Timbers, either round or square, 4 to 10 inches
, staking. in diameter and in varying lengths, are required for
, • Construction Procedures 8-2 1
'
Figure 8.8 Vegetaied geogrid insiallaiion using constrvction jigs and barier boards. ~
1. BANK EXCAVATION & PREPARATION Excavated and ~
FOR FlRST GEOGRID. reshaped bank
Original bank line
~ .
~ .
Live branches, criss-crossed, with
tips extending beyond bank ~ 10_150
~ 3 .
Lightly tamped soil suitable for
rooting, watered thoroughly OHW
. ~:;.-•::,~:;;::::r>;>::~';<;~~:i::~::~:~:::;}::::.; '••,:~s•;»K~;~,y,;»•fk~5...
`•~::k.:,•• ...c:'•'
~ti
-8 in.
6
~
:j:~::
. . .
. .
. . ~
Rock toe key
~ • ~
2. PLACEMENT OF JIGS AND BAITER BOARDS. . Batter boards-approx.
2 in. x 10 in. x 4 ft. (short
lengths to follow bank curves)
Jig ~
2 in. x 6 in.
angle iron upright, Eyelet
3 ft. high
' 4~.,4 , , .
OHW. •
+::.<v•:\`:~:..::~;a'tK::aax;>.•..;2;C::"•.C`~`y~'at;",••,.^.:t,; ::c%\;c;.`;•
~:?\'}•,1;1?j44S:~7;ti{~ i''::`•'.~{i:;;r~i:~:~v:~M1~1>••'.'i'%~v'~J:•:v:iS}
,f:::':S:tiv:4L:l;': :ti?Y:: `¢i<i;:;}i,ti:~:i:}Yi' :4.~:} }iiti:\4 v{vti • ~
1/2 in. x 6 in. «:<:;~;.;:~•,~:k:>fi:„;4,:~::~;:>`;~::,~"ixc;ik``::~~:'.: .
welded iron base, `'<"'~'~~~k:ti;,~•,.~:~~~:;,~~.~{.• . . .
X.~i k,~;.., 'J,.:. ,,;2C`^.~~.~,...~~.~.~,.....•~`.'fi.~`..k'~,•,hk.
k}.i~': 4'y rL,•>};y\;'• ~f lt\•
3 ft. long ~ ~ . .
~ i'~1~~4T'{$~.~~{•~ •
~y i4. j
'
Typlcal angle Iron jig ~ ~ ~ • ~
~ . . ~
3. PLACEMENT OF COIR FABRIC. 1 in. x 2 in.
wood stakes ~
a. Lay fabric pieces an bench, seams Coir fabric
overlapping approx. 1 ft.
b. Stake in place. ~
~
c. Drape excess fabric pHy~v : •.v<.:
:>:aiti;itil[L.+v.i~~+c;2,~'i•;x••i~';'::v:~R:^•,R;:;`>:;xc1t:Y'{~:?q;4:{i\;` 7i
over 1i9• ;~;<;.:,~;~;«{~.;..<~..,~.~;
,.:•:,.~:;•''.~`::?~~`:..;:.:,::,:.:~t.:;~~.: ~ ~ : • ~
' ti ~•:tii ~':~:;;~.::,i;v. ~ `•.,~z;>?<;:'~fi'v',+'.-,~~.,;: J`::v;;;.';';??v.
v:,;.•:~~; :;.~h~s.;.>;:;.}: ;?~*4.~,,;...~:::.: ':.t:?::::•s '
v+: ..•\:;ti}tiii;-{:v.t . . ~ . .
S:ii~yT+v.\':+5~{;:ji+k+"\H'b'•:~k:;:i:'}1:'.,::::~ . . .
. . •d \t~'.. `~'i:~?~'{vti+'+~::..:`~.}':<{ .
:~,.'ti,~..,`,`.".~~~^._,•.; s»::t:+,•>:~;
: t`•'•'S:::.<::••:~::t::: ~:•'.•::::•::.:c:..~ .
secnoNS ~
8-22 Constnuction Procedures '
'
Figure 8.8 Vegeiaied geogrid installation using consfiruction jigs and batFer boards, confinued.
~
~ 4. WRAPPING AND SECURING COIR FABRIC. 1 in. x 2 in.
wood stakes
~
a. Fill bench with soil up to top of batter board, Coir fabric
~
maintaining 10-15° slope. Water soil.
b. Pull fabric up and over to wrap soiL
' Fill soil , ~
c. Stake in place. '
~ . '
~
OH W . {<>rv;.:::. • . . ~ 1-2 ft.
1.4
<'•.i ti~ ::ti: ;?:}tiiv:`
~~':i$itiji+:"LV<~~:~. ~'Li,l:~'
~i::\•;v::\l':i:\•;.;..,v
' .~ti
::?i`::"•~•"i:;'.:•'•:::;i{:jti':i::.. ♦ .
•y} ti•.•:•:•ti:.:}•.::~'.:~i+:~{ :~?!~{{~.::i.:; j•i•}:}r.~ . ~ • . . . .
~;:i'+i:?.+'$.}y? }.itx,'~~~,':::i*vnY''`k{vv..: • . ~ .
~s ti~ ri ~::~~::~'i 4.:v..:: :i... i''l.¢}:::•.ti
;?t~'~~'~•ih'~:~p,`.~ \r"~'~.'~~~{'.<ti>::iM1:~tis;{i'}•iv.
5. REMOVAL OF JIGS AND BATTER BOARDS. 1 in. x 2 in.
~
wood stakes
' Slide jigs and batter boards out. I Coir fabric
~ . ~
.
oHw.• ~
.ti~:.
~";:~#:••'<:•::;<:<::s';z;`•.; ::;'•<:;•'•:;;:~•.<:::;•`•:;.<~s~::~>:.~
. `•C,•
:}~?ih•l}~;:ti~:'•:i:~::;:h•:•:i•'>};:\~vtiS;+:;: i.:4:.;i:'~'\;4:~??v.•
=•Si\1k:~ i:il;' :.::i'::i:>~' i}:j(':::` :}V.r.;'':j'•}'i.:~ l
h: f.i ¢:~.1, u\i.},i:ti:;TV'~v'.;: •y.~{v~~.: ~L;,hx
' .\.~'i'i':~~.~~.x'•.i}::}y::.M1V~.:~.r~~,}\y}.••:. . .
44tiv'•:}•1:+~.~'v:£L~'ti'h?ti....,v?~'..,,:. ~:tit}; • . .
h.:`•:~,,'~t~,;)k.~~~.,~';,c•:,;~::^,:;.``•?.'y,:`ti'.~` •
, ';g:::..;>~;~;;;,4t~.;,,
4:ii(k:'`•}~i~::v.~'•:::i\..`.{:'.:'_.'•.':.y+\~` , .
a.M •..+r+~?+~r:~"
~
6. INSTALLATION OF ADDITIONAL GEOGRID UFTS.
~ a. Lay another layer of live branches and • f~
soil on top of the geogrid and construct :
additional lifts.
~ b. Seed and/or plant upper bank.
c. Water top soil of every layer. ~~•~•f~' ~
' •
OHW. "M;~s~ . '
,
' .
~ SECTIONS
'
, Construction Procedures 8-23
t ~
Figure 8.9 Installation of live cribwall. (AdapUed from Gray and leiser 1982.)
~
~
~
Approximatey 6 in. Undisturbed bankline
v
Header '
~
c~ Stretcher
~ 4 ft. o.c.
PLAN VIEW
(FII meterial rat shown). ~
~
Live branches, placed so not more
. ° , , • - , , . ° , , than 1/4 length extends
° • ' • . . a ~ ° . . : . , • ' . , outside of cribwall ~
Stretcher a . . • Header p Undisturbed
. _ ° • : bankline ~
i.
r
Fill material ~
suitable
for rooting
i.
O W
~
Rock fill
~
' . Rock fill ~ • ' ; ' ~ % o
. . . ; , o°
. . •o• . o. , a•. .
, . . . . . . ~o... o
. ' ~
FRONT ELEVATION SECTION
. ~
NOTES: t
The cribwall can be constructed with either round peeled timbers or square timbers.
Fitl material should be suitable for rooting, but topsoil is not necessary. Ensure even filling of soil over branches, ,
avoiding hollow spaces.
If possible, the basal cut end of branches should extend into the soil behind the wall. ,
'
8-24 Const►uction Procedures ~
the cribwall frame (Figure 8.9). To prevent water Tree Revetment
~ quality degradation, cribwalls should constructed
with non-tneated wood. The material used to back- To construct a tree revetment, trees are laid
fill the crib must include soil that will support plant along the bank with the basal ends oriented up-
~ growth, stream (Figure 8.10). They should be overlapped
Starting at the lowest point of the bank, exca- 0.25 to 0.33 of their length to insure continuous
vate below the anticipated scour line. Construct protection to the bank. The number of trees used
, either a rock toe or begin placing stretchers. Place depends on the length of bank to protect.
stretchers (10 to 12 feet in length) 3 to 4.5 feet apart The trunks are cabled to deadman anchors in
and parallel to each other. The bank stretcher the bank, with the top of one tree overlapping and
' should be only a few inches from the bank. If using cabled to the trunk of the next tree downstream in
rounded timbers, notching will increase the stabil- a shingle-like effect. Piles can be used in lieu of
ity of the joints. Place the headers, typically four deadman anchors, provided they can be. driven
' feet on center, on top of and perpendicular to the well below the point of maximum bed scour. To
stretchers. Secure with rebar or spikes. assure proper cable tension, pull and hold the trees
~ Place the initial rock fill material in the lower in against the bank while the cables are being
poition of the cribwall (up to the OHWM). Place attached. Use cable clamps to attach the cable to
and secure the next layer stretchers on top of the the trees. Cable the tip of the last tree in snugly
~ short right angle timbers. The layers should be against the bank to prevent bank scour at this
spaced approximately the same width as the thick- location.
ness of the timber. Place fill material and compact Do not trim branches of the trees. The use of
' at the OHW mark so that the soil surface slopes green trees will result in less limb loss during
down into the bank at least 10 degrees from hori- installation. Fill large gaps between the trees and
zontal. Start the first layer of live brush at the thebankwithadditional'reesand/orrockas needed.
~ OHW mark. Arrange the branches in the open Rocks and trees together often form a more effec-
spaces between the timbers so that not more than tive structure than either alone. It is important that
0.25 of their length extends beyond the face of the this type of revetment be adequately anchored to
~ cribwall. If possible, the basal end of the branches prevent trees from breaking free and damaging
should be embedded in the native soil behind the downstream structures.
cribwall. When placing fill material over the
~ branches, avoid creating large voids or hollow
spaces; branches in these areas will not root. 8.3.4 HABITAT COMPONENTS
~ Continue with the logs or timbers, soil, and brush
placement to the top of the live cribwall.
The branch cuttings used in constructing live Large Woody Debris
~ cribwalls are similar to those described for brush
. layers. Rooted vegetation (rooted stock) may also Whole trunks with roots and single logs can be
be used. firmly buried into the riverbank or bed, wedged in
' Rocks may be necessary in front of the struc- place with other woody elements and/or rock
ture where the water velocities at the toe are materials, or cabled to buried "deadman," tie-back
expected to be very strong. Large boulders can anchors or other structures, or even living trees.
~ also provide cover and refuge areas for fish. Cables can also be fixed to the logs and glued with
Construction of cribwalls is discussed in detail epoxies into holes drilled into large rocks. Other
by Gray and Leiser (1982). These authors discuss emplacements rely on pounding long lengths of
~ numerous cribwall designs of varying size and steel reinforcing bar into underlying sediments
complexity. through holes drilled through the wood pieces.
Root wads or stumps may be firmly wedged,
cabled or nailed in place with rebar. Cabling can be
Consfixtion Procedures 8-25
~
Figure 8.10 Insrollaiion of a kee revehnent.
~
Deadman ~
~ • ~Anchor cable
• : • ' • • • • ' i• . . • . .
. ~
. len9th . -.4k-=;__ . A•: .
vane
. . . : .
. ~ . .
.
. •r ,
T ~
• •
..l
- ~
``O~•t . . . . . , . , . . ~
. . . ' ' ' ~
PLAN VIEW ~
~
' ' : ~
. ' : . _ OHW
~
'•:w•'.A: • .
~ Anchor.• ' '
cable • ° ,
Deadman ' ' ' • . ~
• . o .
. . : e . : . .o_ .
. , a..
. . ~
SECTION
'
accomplished by drilling through the root and/or cabled, precautions should be taken to minimize
stump portion, passing a cable through the hole, possible movement or shifting of these devices. ~
and cementing each end of the cable to a large Project designers should also be aware that each
rock. A variation is to swage (i.e., crimp) a ferrule piece of wire rope introduced into the river system
(i.e., bushing) around the cable; the free end is is a potential hazard to swimmers, boaters, rafters, '
passed through a hole drilled through the center of and wildlife.,
the root and up through the center of the tree rings. In large river systems such as the Green or
The cable is then epoxied into a large boulder. If Cedar Rivers, secure large woody debris (prefer-
8-26 Construction Procedures ~
' t
ably 20 feet long or more and 20 inch minimum into the bankline itself. In both cases, the logs
~ diameter) by burying them directly into the rock should be secured firmly in place with large rock
tce buttress (Figure 8.11) (A. Levesque, King (three to five foot minimum diameter rock), with
County SWMD, pers. comm.,1992). Where facil- a minimum of four to five rocks placed along its
` ity reconstruction will allow, this can occur with- length. Smaller stone and granular materials may
out further excavation into the bankline. In other be needed to fully embed the log in fine-grained
cases, especially where setback modifications to bed or bank excavation materials. The root end of
!j the facility alignment are proposed, a trench may the log should protrude from five to eight feet
be required to embed the top of the log partially beyond the edge of the rock installation, at a 30 to
'
Figure 8.11 Integrated system using large woody debris. ~
~Top of 6ank
~ Staked fascine
' Coir geogrid
Live cuttings
' 2 ft. minimum layer ' . ' • . . ~ ~ '
heavy-loose riprap _ • , 3-5 ft. minimum . . .
diameter rock 44k
~ '
- ) ~ •
J . .
.
, ~ / • • • 1 ft. minimum layer
• ' of light-loose riprap
r . ~
, - , 1-1 1/z ft. layer of 1/4-3 in.
. _ . - ' ' • ' • ' • - , rounded gravel
~ . . • . . .
2 ft. diameter, 20-30 ft. long log with roots.
Trench and imbed log bole 12-16 ft. minimum
distance into riverbed below existin9 OHWM.
~
Secure with rock tce.
~
Construcfion Procedures 8"27
,
. L ~
45 degree angle to the bankline and at 2 to 20 $.4 CONSTRUCTION INSPECTION
degrees downward towards the streambed. The AND SITE CLEANUP ~
entire log should be placed below OHW to keep it
fully saturated at lower flows. It is recommended Site inspection and construction monitoring
that layers of woody vegetative cuttings and top- must occur during project installation to ensure ~
soil be placed directly over the full dimension of that the design specifications are met. While fa-
the log and rock emplacement. The vegetation cilities can be adequately designed, projects will
should be deeply rooting and tolerant of saturated not be successful if construction materials do not ~
soils. meet the required specifications or if the materials
were installed improperly. Many of the items
listed in Section 8.1 are activities that occurthrough- ,
. Fishrocks out construction of the project. At the close of
construction, the project supervisor should ensure ~
The proper rock position in the flow depends that all elements of the design have been installed
upon its shape, the angle at which the flow hits the according to specifications. Any changes to the
rock, and the site objectives. Place rocks such that, design specifications should be documented as ~
at bankfull discharge, the flow is deflected toward revisions to the final design drawings to reflect the
the area where the scour is desired. Orsborn and as-built condition of the project.
Bumstead (1986) recommend placing the long At the end of each work day, construction ~
axis of the rock parallel to the flow. This orienta- sites, especially in residential areas, should have
tion reduces the chance of the boulder tipping into construction debris, plant materials, soil, tools,
its scour hole and is less likely to direct the flow and other material picked up from roads and other ~
into the bank. To ensure the stability of rocks, azeas. The site should be left as neat as possible and
align them with the flow so that the flow will not practical every day. During the day, vehicles and
rotate them. equipment not in use should be stored out of the ~
Avoid placing rocks so that flow is directed way of local residents or businesses. These mea-
into erodible banks (Wesche 1985). Before install- sures help maintain friendly relations with people
ing, examine the stability o.f a fishrock from three inconvenienced by the presence of equipment and I
perspectives. First, the shape and orientation ofthe work crews.
rock will have an impact upon the depth and Advance planning and organization of the
volume of scour. Second, expect upstream rota- work site also eliminates rearrangement of stock- ~
tion of the fishrock as most undercutting will occur piled materials. Items should be kept readily avail-
on the upstream face of the rock. Under high able, but not in the way of workers or equipment. ~
velocities, the fishrock may become cantilevered The azea immediately adjacent to the streambank
and tip into the scour hole it has created. Finally, usually must be kept clear to allow equipment
expect an elongated rock to naturally shift its access where it is needed. When several stabiliza- ~
major axis at least 45 degrees to the flow. Plan for tion components will be used, areas should be
this and initially install elongated rocks approxi- identified for these specific materials so that the
mately parallel to the flow since this orientation is quantities available can be determined quickly ~
more naturally stable. and clean-up is organized. It is preferable not to
Whenever possible, use equipment stationed store cut plant material overnight; if it must be,
on the bank to place rock. In larger rivers, instal- provide an area where the stems can be covered ~
lation of fish rocks may require operation of equip- with moist (not wet) soil or stored with the basal
ment instream. ends in the stream.
At the completion of a project, staging areas ~
should be restored to preconstruction conditions.
Remove unneeded or scrap material that could
endanger wildlife or enter the stream, and repair ~
8-28 Construction Procedures ~
~ . ~
damage to property, landscaping, lawns, and drive- ways caused by the work. Grade and reseed dis-
turbed lawns or areas that may be subject to
surface erosion.
~ If possible, return plant containers to the nurs-
ery or to a recycling or redistribution center. Many
nurseries give cash or credit towards future pur-
~ chases for rEturned plant containers. Clean Wash-
ington Center (206-464-7040) and the Industrial
Materials Exchange (IMEX) (206-296-4899) are
~ two organizations involved in waste reduction and
who can provide information on how to acquire or
~ dispose of many recyclable and reusable products.
This includes landscaping materials such as com-
mercial compost and plant pots.
~
~
, .
~
~
~
~
Construction Prxedures 8-29
L ~
RECOMMENDED SOURCES FOR
ADDITIONAL INFORMATION ~
,
Coppin, N.J. and I.G. Richards. 1990. Use of
Vegetation in Civil Engineering. London, ~
England.
Gray, D.H. and A.T. Leiser. 1982. Biotechnical ~
Slope Protection and Erosion Control.
Van Nostrand Reinhold Company. New
York, N.Y. ~
Schiechtl, H. 1980. Bioengineering for Land*
Reclamation and Conservation. University ~
of Alberta Press. Edmonton.
~
~
~
~
~
~
~
~
~
~
~
8-30 Constnuction Procedures ~
~ -
~ CHAPTER 9
LONG-TERM SITE MANAGEMENT
ro'ect of the toe area can help prevent failures by identi-
~Frequent inspection and maintenanceofp~
sites is important so that any damage that occurs fying damage before it progresses to failure. In-
~ can be repaired before it progresses to major spection of the toe zone should occur during low
failure. Streambank erosion inventories can be water periods when the toe is more likely to be
updated by identifying new erosion sites and re- exposed to view.
' evaluating old sites. It also provides an opportu- Areas below the ordinary high water mark
nity to identify potential sites for habitat improve- should be inspected for evidence of stone move-
~ ment that might be implemented during routine ment along the toe or streambank erosion that
maintenance operations. Inspections also provide could undernune the toe. The following condi-
an opportunity to observe untreated banks. tions may suggest a need for repairs:
Areas of bare soil within the toe zone; '
9.1 INSPECTIONS AND • Horizontal displacement of individual rocks
~ MONITORING or sections of rock within the tce zone;
• Scour along the toe that results in loss of
Regular periodic inspecdons should be made support to the upper bank;
' after bank stabilization measures have been in- • Evidence of bed degradation, headcuts, or
stalled. All projects should be inspected at least scour holes that might undermine the toe;
annually; newly installed projects should be in- and
spected after the first major high flow. Each • Movement or loss of lazge rock protecting
project should be monitored to evaluate changes the foundation of cribwalls or movement
occurring at the site. Ground photos should be (settling, tilt, or horizontal displacement) of
` taken periodically at established photo points. the structure.
These may be supplemented by aerial photos on
large projects. Photos should be taken at least The loss of rock from rock revetments and
~ twice a year, ideally in the spring and in the fall. To levee faces should be monitored at least yearly
allow comparisons among repeated photographs, (prior to the flood season) and after each major
photographs should be taken during low water flood. This inspection may include quantifying
~ periods and at corresponding water levels. Over- the loss of rock from the face and toe of the facility.
lays made from these and subsequent photographs Estimates of missing toe rock can be made visually
~ will assist in identifying changes. Photogrammet- from the bank or boat. Deep depths or turbid water
ric measurements can then be made on the over- along the toe area may require the use of a
lays to document the extent of plant growth or fathometer to delineate the extent of erosion.
~ areas lost to erosion after project installation. If
post-project erosion is present, an evaluation of its
mode and cause should occur while collecting 9.1.2 VEGETATIVE SYSTEMS
' ground photos.
The development of the vegetation should be
monitored and correlated, at least visually, to the
~ 9.1.1 ROCK STRUCTURES degree of or lack of erosion occurring on the
treated streambank. Plantings are assumed to be
Most conventional bank protection structures effective if the vegetation is growing well in all
~ fail because of undernuning. Careful inspection bank areas of the project and aerial or ground
- 9-1
~ Long-term Site Management
y ~
reconnaissance suggests erosion is not occurring. teaf edges indicate that the plant is suffering from
The frequency of monitoring plant survival should droubhc, either directly through lack of soil mois- ~
ture or indirectly throuah the inability of the roots
be a minimum of once per growing season (pref- to exploic a sufficiently lazge volume of soil. Com-
erably near the end of summer) for at least three pedcion from surrounding dense vegetation is also
consecutive years. Vegetation, especially unrooted a frequent cause of drought stress. Dark green, or
cuttings, may take three years or more to become sometimes reddish, leaves associated with poor
fully established. growch may indicate phosphate deficiency. In
Successful plant establishment, which may be unseasonably cold weather many plants take on a ~
defined by the percentage survival and total ground bluish or reddish tinae, which disappears when
normal conditions return.
cover, may vary among projects. General success ~
criteria are listed in Table 9.1. Common problems Poor growth is caused by many factors but is
encountered in establishing vegetation, their diag- usually associated with poor soil and root develop-
nosis, and general remedies are listed in Table 9.2. menc. Trees chat put on very 1itcle shooc growch in ~
Coppin and Richards (1990) offer the following the first year after planting will probably never
grow well, as the root system may by permanently
advice for evaluating growth performance of veg- damaged pruning back che cop growth co reduce
etation: the demands on the faltering root system can some- ~
times help.
Color is a widely used indicator but must be inter-
preted with care. Yellowing leaves indicate nutri- Woody plants should be monitored for sur- ~
enc deficiency, particularly of nitrogen, which may vival and vigor in each bank area on the treated
be due to infertility in the soil. It can also be due to
impaired functioning of the roots in absorbing streambank. This may be accomplished by mazk-
nutrients, resulting from low or high pH, wacerlog- ing 10 percent of the woody vegetation in each ~
ging,soilcompactionordisease. Brown and papery area with a stake. Each marked plant is revisited
~
Table 9.1 Evaluation criieria for streambank vegetation.
CATEGORY DESCRIPTION
Good Niney (90) percent or more of the bank is protected by vegetative cover and
at least seventy-five (75) percent of the cover consists of woody plants. Plants ~
are growing vigorously (new growth, green stem and leaves, no yellowing of
leaves). ~
Fair Fifty (50) to niney (90) percent of the bank is protected by vegetative cover
and at least fifty (50) percent oE the cover consists of woody plants. Plants are ~
growing, but stable (no new growth, just green).
Poor less than fifty (50) percent of the bank is protected by vegetation and less than
twenty-five (25) percent of the cover consists of woody plants. Plants are
declining in vigor (stem deteriorating, leaves dropping, yellowing of leaves).
~
~
9-2 Long-term Site Manogement ~
Table 9.2 Common problems of vegetation establishment, iheir diognosis and remedies.
~ (Adapied from Coppin and Richards 1990.)
' SYMPTOMS CAUSE DIAGNOSIS REMEDIES
Ground covers
~ ,e,cidiy pH <5.5 Limin9
legumes disappear low phosphorus Exkactable P lest P-iertilizer
~ Grau oompeti6on Grau height > 12 in. Graze or cut
Poor grawlh, prone to $oil compoction Padcing densiy' > 1.75 (mg/m') Cultivation
drought in wmmer,
~ shallaw rooting; pale color Wpterlcgging Water table <15 in. From surfOae Drainage, use toleront species
Extractable nuirient low Add feAilizer, use legumes
Nutrient deFicienry
Low cation exchange Add wganic amelioranls
~ Poor gro+vth, moribund
Acidiy pH <5.5 Add lime, use toleronf species
Drought Low AWC', coarse soil Mexlure Add organic omeliornnt
~ Nutrient deFiciency as above as above
Thick malted grass,
moribund, no Acidity as above as above
~ decomposition
Law N in vegetotion C/N mtio >25 Add N-Fertiliur, grazing
GrowTh too dense ond Presence oF aggressive weed :.ut regubrly and nmore herboge
vigorous soil too 6iiie species ro reduce soil Fertiliy
Trees and Shrubs
Poor stock or bad handling ,qll site Focrors are xrtisFacto nt
Failure ro establish and plan6ng ry
~ ensiy >1.75 (m9/m') Cultivule
Dieback or death, poor Spil ~mpadion Packing d
root growlh, foliage Planting pit impertneable Replont
cobred a Sicky
~ Walerlogging High waler roble < 2 k. deep Droinage
Nutrient deFicienry Foliar and/or soil analysis Fertilize
qcidih, pH outside preferred ronge Lime
~ Poor grawlh rales lcw rainfall; (ow AWC, ~arse
Drought ~~e Mukhes; watering
~il Competition from ground Dense vegebation around trees Ameliorotpn With °f9°^K maMer
~ cover Mulch or herbicide ro suppreu
Damaged, disfigured or $ymptoms of fungi or insect artadc Pest control; prune or fell affected
~ discolored (oliage, buds Disease hees, remwe and burn
and stems
~ ' Pocking Densiy = Dry bulk densiy of soil in situ (mg/m') +t0.009 x X clay)
z AWC = Avoiloble wnter capocity
~
~ lAng-term Siie Management 9-3
ti I
periodically to decide whether it is live or dead and Depending on the severity of undercutting, scour
~
observe the vigor of its growth. The percent holes that might undermine the toe of a structure
survival can be deternuned by dividing the num- may need to be filled with rock. If the integrity of
ber of live plants by the original number staked. the structure is threatened, the cause of the scour ~
Vigor can be determined subjectively by assign- should be conected as well.
ing each marked live plant a vigor class suggested Permanent access roads for inspection and
in Table 9.1. In general, growth should be continu- maintenance should be provided at the time projects ~
ous, with no open spaces greater than two feet in are constructed. Access roads should be main-
dimension. Areas smaller than this will generally tained to allow movement of heavy equipment and
fill in and not hamper the integrity of the vegeta- materials that might be needed in repair work. In ~
tive system. situations where a setback levee has been con-
A periodic measurement of ground cover will structed, the bench area functions as an access
determine if vegetation, herbs in particular, is route for heavy equipment when toe key repairs ~
successfully spreading across the site. Measure- are required. Locked gates may be desired to
ments of stem densities are needed to find if restrict public entry to dangerous or sensitive
woody cuttings and fascines are sprouting and azeas. ~
adding to the vegetative composition and density. Most plant losses occur the first year with
Both factors can be measured by establishing one fewer losses in successive yeazs. Irrigarion, dis-
square meter plots randomly throughout the bank ease and pest control, and replacement of dam- ~
area until a one percent sample is achieved. These aged structures improves slope stabilization
plots should be permanently established immedi- projects by increasing plant density and allowing ~
ately after planting and delineated by well-marked identification and prompt correction of minordam-
stakes. age. Vegetative repairs should be performed dur-
Ground cover for each plot can be detern-uned ing the dormant season following the first year's ~
by using visual estimates of live vegetation in growth. Dead plant material should be replaced
different cover classes. Each cover class is as- where possible. Seriously damaged areas (e.g.,
signed a number and recorded on the data sheet for gullies, rills, and washouts) should be repaired by ~
that plot. Once the percent ground cover has been restocking or reconstruction. Insect and disease
determined for each plot, composition by domi- infestations should be controlled.
nant species is estimated and a list of the dominant Otherprocedures formaintaining existing veg- ~
plant species for each plot prepared. Stem densi- etation involve pruning, selective cutting, and
ties of woody plants are determined by species for selective spraying. Pruning is usually performed
each plot by counting the number of stems. This to eliminate shade and encourage growth of plants ~
gives an. estimate of number of stems per species that need direct sunlight. Undesirable plants are
per square meter. removed by selective cutting.
A program of selective vegetative manage-
ment should be developed to preserve vegetation ~
9.2 MAINTENANCE with good existing habitat value and to promote
development of fish and wildlife habitat in se- ~
Damage to the tce zone usually is repaired by lected areas. Vegetation management strategies
adding rock or by replacing lost or displaced rock. should identify targeted fish and wildlife species,
Rock can be individually placed with equipment plant species with appropriate habitat characteris- ~
having a"rock-picker" implement or dumped; tics, and a vegetative management plan that will
when possible, individual placement is recom- preserve and promote growth of the selected plants.
mended because it allows better keying. Large Chapter 6 provides information about the habitat ~
rock, Dl00 or larger, should be used for replace- value of various plants. Because habitat food and
ment. If the filter layer has been damaged, it cover values depend on plant form and growth
should be repaired before the rock is replaced. stage, habitat programs often take longer to estab- ~
94 Long-term Site Management ~
~ L
lish than other project components (up to 10 years
~ is not uncommon).
In recent years restrictive federal vegetation
standards for revetments have been relaxed to
~ allow for some growth of woody vegetation. The
Portland District of the Corps of Engineers
(USAED, Portland, 1980) revised maintenance
~ criteria for Willamette River revetments follow-
ing the discontinuation of broadcast spraying for
vegetation control. The adopted selective clearing
~ criteria called for removal of woody growth two
inches or more in diameter or six feet or more in
~ height and the removal of all vines. Similarly, the
Seattle District (USAED, Seattle,1982) adopted a
modified vegetative management plan for
~ riprapped levee slopes on the Green River in King
' County that allows dogwood, willow, and wild
rose on the upper portion of the levee. Similar
~ changes are being developed for the Sammamish
River.
~
~
i
~
~ Long-iertn Siie Management 9-5
RECOMMENDED SOURCES FOR ADDITIONAL INFORMATION ,
Coppin, N.J. and I.G. Richards. 1990. Use of
Vegetation in Civil Engineering.
Butterworths. London, England. ~
Gray, D.H. and A.T. Leiser. Biotechnical Slope Protection and Erosion Control. Van ~
Nostrand Reinhold Company. New York,
N.Y. ~
Schiechtl, H. 1980. Bioengineering for Land
Reclamation and Conservation. ~
University of Alberta Press. Edmonton. '
~
~
. ~
~
.
~
~
~
~
9-6 long-term Site Management ~
~
GLOSSARY
~
Accelerated Erosion: Erosion that is greater Base Flood Elevation: The water surface
than . the erosion experienced at the site in the elevation of a flood having a one percent chance of
recent past. being equaled or exceeded in any given year.
Commonly referred to as the "100-year flood".
~ Aggradation: The long-term hydraulic pro-
cess by which streambeds and floodplains are Base Level of a Stream: The elevation (e.g.,
~ raised in elevation by the deposition of materials. lake, reservoir or river) below which a stream
It is the opposite of degradation. See also channel cannot erode its bed.
scour and fill.
~ Bed Load: Sediment moving along or near
Alluvial: Deposited by running water. the streambed and frequently in contact with it.
See also suspended load.
~ Anadromous: Born in freshwater, migrating
to and living in salt water, and then returning to Bed Slope: The gradient from the horizontal
freshwater to reproduce. plane of-the channel bottom.
~ Armoring:(a) The natural process of fornung Bend: A change in the direction of a stream
an erosion resistant layer of relatively large par- channel in plan view.
~ ticles on the surface of the streambed. (b) The
artificial application of various materials to Benthic: Of or pertaining to animals and
strengthen streambanks against erosion. plants living on or within the substrate of a water
~ body.
Available Water Capacity: The capacity of
soils to hold water for use by plants. Berm: A levee, shelf, ledge or bench along a
streambank that may extend laterally in the chan-
Bank Failure: Collapse of a mass of bank nel to partially obstruct flow, orparallel to the flow
material into a stream channeL to contain the flow within its streambank. May be
natural or constructed.
Bankfull Discharge: The discharge corre-
sponding to the stage at which the natural channel Blanket: Material placed on a streambank to
~ is full. This flow has a recurrence interval of 1.5 cover eroding soil. See also revetment.
to 4 years depending on the channel gradient and
bank materials. Boulder: Sediment particle having a diameter,
~ greater than 256 mm (10 inches).
Bar: (a) Accumulation of alluvial material
~ along the banks, mid-stream, or at the mouth of a Braided Stream: A stream that forms an
stream or in the wakes of objects where a decrease interlacing network of branching and recombin-
in velocity induces deposition. (b) An alluvial ing channels separated by branch islands or chan-
~deposit composed of sand, gravel, or other mate- nel bars.
rial that obstructs flow and induces deposition or
transpoR.
~
~ Glossary GL I
Brush Mattress: A mattress-like covering Clay: An extremely fine grained sediment,
that is placed on top of the soil. The covering having high plasticity. Individual particles have a ~
material is living woody plant cuttings that are diameter less than 0.004 mm (4 microns) and are
capable of rooting. not visible to the unaided human eye. If moist,
clay can be molded into a ball that will not crumble: '
Caving: The collapse of a streambank by
undercutting due to wearing away of the tce or an Cobble: Sediment particles largerthan pebbles
erodible soil layer above the toe. and smaller than boulders: Usually 64 - 256 mm ~
(3 to 8 inches) in diameter.
Canopy: The overhead branches and leaves
of riparian vegetation., Cohesive Soil: Soils that have natural resis-
tance to being pulled apart.
Canopy Cover: Vegetadon projecting over a ~
stream, including crown cover (generally more Coir: A woven mat consisting of coconut
than 3 feet above the water surface) and overhang fibers. Generally used for various soil erosion
(less than 3 feet above the water surface). control practices such surface slope protection and ~
the construction of geogrids.
Capillary Fringe: The distance water is
wicked upwards above a water table by capillary Cover: Anything that provides protection for
acNon in the soil. fish and/or wildlife from predators or amelivrates
adverse conditions of streamflow and/or seasonal
Channel Roughness: The irregularity of stre- changes in metabolic costs. May be instream ~
ambed material sizes and channel form in plan and structures such as rocks or logs, turbulence, and/or
cross-section that causes resistance to flow. overhead vegetation. Anything that provides ar-
eas for escape, feeding, hiding, or resting. ~
Channel Scour and Fill: Erosion and sedi-
mentation that occurs during relatively short peri- Cross Section: A vertical section of a stream
ods of time; degradation and aggradation apply to channel or structure that provides a side view of ~
similarprocesses that occur over a longer period of the structure; a transect taken at right angles to
time. flow direction.
Channel StabilitY: A relative measure of the Current: The flow of water moving in a ~
resistance of a stream or river to erosion. Stable particular direction. See also velociry. ~
reaches do not change markedly in appearance
from year to year. Cut Bank: The steep or overhanging slope on
the outside of a meander curve, typically produced ~
Channel Top Width: The horizontal dis- by lateral erosion of the stream.
tance along a transect line from top of bank to top
of bank, measured at right angles to the direction Cut Off: A channel cut across the neck of a
of flow. Multiple channel widths are summed to bend. ~
represent total channel width.
D30, Dso, Dloo: The particle size for which 30, ~
Channel: A natural or artificial waterway that 50, and 100 percent of the sample is finer:
periodically or continuously contains moving wa- ter. It has a definite bed and banks that confine the Dead Stakes: Stakes, varying in length, made
water. from lumber used to hold fascines and brush
mattresses in place. Also used to anchor fabric in
the construcrion of geogrids. ~
~
G~2 Glossory
Debris: Any material, organic or inorganic, Enhancement: Improvements to the existing
floating or submerged, moved by a flowing stream. condidons of the aquatic, terrestrial, and recre-
See also large woody debris. ational resources.
~ Degradation: The long-term hydraulic pm- Erosion: In the general sense, the wearing
cess by which stream and river beds lower in away of the land by wind and water. As used in this
elevation. It is the opposite of aggradation. document, the removal of soil particles from a
~ bank slope primarily by water action.
Deposition: The settlement of material out of
the water column and onto the streambed or flood- Fascine: Sausage-like bundles of living woody
~ plain. Occurs when the flowing water is unable to plant cuttings that are tied together. These fabri-
transport the sediment load. cated structures are capable of rooting. Also
~ contour wattles.
Detritus: A non-dissolved product of disinte- called
gration or wearing away. Pertains to organic or Fill: (a) The localized deposition of material
~ inorganic material. eroded and transported from other areas that re-
sults in a change in streambed elevation. (b) The
Discharge: The volume of water passing deliberate placement of organic and inorgamc
~ through a section of channel during a given period materials. .
of time. Usually measured in cubic feet per second
or cubic meters per second. Filter: Layer of fabric, sand, gravel, or graded
~ rock placed between the bank revetment or chan-
Drag Force: The force component exerted by nel lining and soil for one or more of three pur-
a moving fluid on any object submerged in the poses: to prevent the soil from moving through the
~ fluid. The direction of the force is the same as that revetment; to prevent the revetment from sinking
of the free stream of fluid. into the soil; and to permit natural seepage from
the streambank, thus preventing buildup of exces-
~ Drainage Basin: A land surface collecting sive groundwater pressure. Also called filter layer
precipitation into one stream. Sometimes refened or filter blanket.
to as a watershed.
~ Fine aggregates: Fine grained particles hav-
Dripline: An imaginary line around a tree or ing diameters less than 0.25 inch.
shrub at a distance from the trunk equivalent to the
canopy spread. Fish Habitat: The aquatic environment and
the immediately surrounding terrestrial environ-
Eddy: A circular water movement that devel- ment that meet the necessary biological and physi-
'i r ops when the main flow becomes separated from cal requirements of fish species during various life
its confining boundaries. The eddy current, which stages.
typically runs contrary to the main current, usually
~ occurs in ihe region between the main flow and the Flanking: Streamflow around a structure and
boundary. into the bank that can lead to failure of the struc-
~ ture.
Energy Dissipation: The loss of kinetic en-
ergy of moving water due to internal turbulence, Floodplain: Any lowland that borders a stream
~ boundary friction, change in flow direction, con- and is inundated periodically by its waters.
traction or expansion.
Fluvial: Produced by moving water.
~
Glossary C'3
~
. ~
Freeboard: The vertical distance between the Headcutting: The action of an upstream
design water surface elevation and the elevation of migrating waterfall or locally steep channel bot- ~
the bank, levee or revetment that contains the tom with rapidly flowing water.
water. Aydraulic Control Point: The top of an ~
Froude Number: A dimensionless number obstruction to which water must rise before flow-
used to characterize the type of flow in open- ing over or a point in a stream or river where the
channel hydraulics. It is the ratio of inertia forces flow is constricted. ~
to gravity forces. It is equal to the mean velocity
of the system divided by the square root of the Hydraulic Energy Gradient: In a stream, the
product of a characterisric linear dimension (e.g., slope of a line representing the sum of kinetic and ~
depth), and the acceleration due to gravity--all potential energy along the channel length. It is
expressed in consistent units. equal to the slopes of the water surface and stre- ~
ambed in steady, uniform flow.
Gabion: A galvanized wire basket with a
hinged top, intended to be filled with stones and Hydraulic Radius: The cross-sectional area ~
used to stabilize banks or channel beds, to control of a stream or river divided by the wetted perim-
erosion, and to prevent bed material from shifting. eter.
Generally not recommended for placement in ~
gravel bed streams. Hydrophyte: A plant that can tolerate soils
that are oxygen-poor as a result of saturation.
Glaciolacustrine: Pertaining to glacial lakes. ~
Impermeable: Properties that prevent the
Glaciolacustrine Deposits: Sediments, typi- movement of water through the material.
cally composed of silt or clay, deposited in glacial ~
lakes. Infiltration: The portion of rainfall that moves
downward into the subsurface rock and soil.
Gravel: Sediment particles larger than sand ~
and ranging from 2 to 64 mm (0.25 to 3 inches) in Instream Cover: (a) Areas of shelter in a `
diameter. stream channel that provide aquatic organisms
protection from predators or competitors. (b) A ~
Groundwater Flow: Water that moves place in which to rest and conserve energy due to
through the subsurface soil and rocks. a localized reduction in the force of the current. ~
See also habitat, fish habitat.
Groundwater Table: The level below which
the soil is saturated, that is, the pore spaces be- Jack: A young male salmon that matures ~
tween the individual soil particles are filled with precociously.
water. Above the groundwater table and below the
ground surface, water in the soil dces not fill all Joint Planting: The process of placing live ~
pore spaces. woody plant cuttings in the spaces between pieces
of rock riprap. When placed properly, the cuttings
Habitat: A place where a biological organism are capable of rooting and growing. ~
lives. The organic and non-organic surroundings
that provide life requirements such as food and Large Woody Debris: Any large piece of
shelter. See also cover, fish habitat, and instream woody material that intrudes or is embedded in the ~
cover. stream channel. Also called large organic debris.
~
G-4 Glossary
~
Lift Force: The force component exerted on Piping: Flow 'of water through subsurface
~ a body submerged in moving turbulent fluid. The conduits in the bank.
force acts in a vertical direction perpendicular to
the free stream of the fluid. Potadromous: A migratory fish that lives and
~ migrates only in freshwater. These fish are some-
` Live Cribwall: A rectangular framework of times referred to as river- migratory or lake migra-
logs or timbers constructed with living woody tory fish.
plant cuttings that are capable of rooting.
Reach: A length of stream that has generally
Live Stakes: Live, woody plant cuttings, similar physical and biological characteristics.
~ capable of rooting, that are faken from shrubs and
trees. Redd: Egg nest made in gravel by fish. It
consists of a depression and associated gravel
Manning's "n": The resistance coefficient in mounds hydraulically dug by fish for egg deposi-
the Manning formula used in calculating water tion.
~ velocity and stream discharge. It is a proportion-
ality ccefficient that varies inversely as a function Revetment: A facing of stone, wood or any
of flow. other materials placed on a bank as protection
~ against wave action or currents.
Noncohesive Soil: Soils that have little natu-
ral resistance to being pulled apart at their point of Riparian Area: The area between a body of
contact. Typically soils such as sand and gravel. water and adjacent upland areas that is identified
~ by distinctive soil and vegetative characteristics.
Ordinary High Water Mark: The mark
along a streambank where the waters are common Riparian Buffer: Trees and shrubs growing
and usual. This mark is generally recognized by parallel io a stream that reduce the intrusion into
the difference in the character of the vegetation the top bank area by humans, animals, and ma-
~ above and below the mark or the absence of chinery. This vegetation also retards surface run-
vegetation below the mark. off down the bank slope and provides a root
. system which binds soil particles together.
~ Overbank Flow: Water flowing over the top
of bank. Riparian Vegetation: Vegetation growing
along the banks of streams and rivers or other
~ Overhead Cover: Material (organic or inor- bodies of water tolerant to or more dependent on
ganic) that provides protection to fish or other water than plants further upslope.
aquatic animals from above. Generally includes
material overhanging the stream. See also canopy Riprap: A layer, facing, or protective mound
and canopy cover. of stones placed to prevent erosion, scour, or
sloughing of .a structure or embankment. Also
Point Bar: A bar found on the inside bank of refers to the stone used.
a river at a bend.
Roughness Element: Any obstacles in a
~ Phreatophytes: Plants growing on or near the channel that deflect flow and change its velocity.
streambank with their roots in ground water or the
~ capillary fringe. Rubble: Loose, irregularpieces of artificially
broken stone as it comes from the quany.
~
Glossary GS
~
~
Salmonids: Fish of the family Salmonidae, Specirications: A detailed description of par-
including salmon, trout, char, whitefish, ciscoe, ticulars, such as size of stone, quantity and quality '
and grayling. of materials, contractor performance, terms, qual-
ity control, and equipment.
Sand: Mineral particles ranging from 0.0625 ~
to 2 mm (0.0025 to 0.08 inch) diameter; 0.03 inch Stream Power: A measure of the rate of
is the normal lower limit at which the unaided change in potential energy available for moving ~
human eye can distinguish an individual particle. rock, sediment particles, or other debris in the
stream channel. Deternuned by the product of
Scour: Concentrated erosive action of flow- discharge, water surface slope, and the specific ~
ing water in streams that removes material from weight of water.
the bed and banks.
Streambank Erosion: Removal of soil par- ~
Sediment Load: The sediment transported ticles from a bank slope primarily due to water
through a channel by streamflow. - action. Climatic conditions, ice and debris, chemi-
cal reactions, and changes in land and stream use ~
Sediment: Soil particles that have been trans- may also lead to bank erosion.
ported and/or deposited by wind or water action.
Streambank Failure: Collapse or slippage of ~
Seepage: Groundwater emerging on the face a large mass of bank material into the channel.
of a streambank or hillside slope.
Streambank: The portion of the channel
Shear Strength: The internal resistance of a cross-section that restricts lateral movement of
body to shear stress. Typically includes frictional water. A distinct break in slope from the channel
and cohesive components. Expresses the ability bottom. ~
of soil to resist sliding.
Streambed: The substrate plane bounded by
Shear Stress: The force per unit area tending the stream banks over which water moves. Also ~
to deform a material in the direction of flow. called stream bottom. It is the area kept mostly or
. completely bare of vegetation by the wash of
Silt: Slighdy cohesive to noncohesive soil waters of the stream.
composed of particles that are finer than sand but
coarser than clay, commonly in the range of 0.004 Streamflow: The movement of water through ~
to 0.0625 mm. Silt will crumble when rolled into a stream channel. See discharge.
a ball.
Structure: (a) Any object in the channel that
Sinuosity: A measure of the amount of a affects water and sediment movement. (b) The
river's meandering; the ratio of the river length to diversity of physical habitat within a channel.
the valley length. A straight channel has a sinuos- ~
ity of 1.0; a fully meandering river has a sinuosity Substrate: The mineral and/or organic mate-
of 2.0 or greater. rial that forms the channel bed.
Sloughing: The downward slipping of a mass Surface Runoff: That portion of precipitation . ~
of soil, moving as a unit usually with backward that moves over the ground toward a lower eleva-
rotation, down a bank into the channel. Also tion and does not infiltrate the soil. ~
called sloughing off or slumping.
~
~
G~6 Glossary
~
Suspended Load: The part of the total sedi- Velocity: The distance that water travels in a
' ment load that is carried for a considerable period given direcdon in a stream during an interval of
of time at the velocity of the flow, free from time.
contact with the streambed. See also bed load.
~ Watershed: An area of land surface defined
Texture: Refers to relative proportions of by a topographic divide that collects precipitation
clay, silt, and sand in soil. into a stream. Sometimes referred to as a drainage
~ basin.
Thalweg: A line following the deepest part of
the bed or channel of a stream. Wavelength: The. distance between succes-
~ sive inflection points, or other corresponding parts,
Tied In: An expression used to indicate that a in a series of ineander bends.
structure is constructed to prevent streamflow
~ between the structure and the bank. Weathering: Physical disintegration orchemi-
cal decomposition of rock due to wind, rain, heat,
~ Toe: The break in slope at the foot of a freezing, or thawing.
streambank where the bank meets the bed.
Weephole: A small opemng or pipe left in a
Top of Bank: The break in slope between the revetment orbullchead to allow groundwaterdrain-
streambank and the surrounding upland terrain. age.
Tractive Force: The drag on a streambank or Wetted Perimeter: The length of the wetted
bed particles caused by passing water which tends contact between a stream of flowing water and the
to move soil particles along with the streamflow. stream boundary, measured in a vertical plane at
right angles to the direction of flow.
~ Transect: (a) A predeternuned line along
which vegetation occurrence or other characteris- Woody Debris: See large woody debris.
~ tics such as canopy density are counted for moni-
toring purposes. (b) A channel cross-section.
~ Turbulent Flow: A state of flow of water
where local velocities fluctuate and the direction
of flow changes abrupdy and frequently at any
~ paticularlocation, resulting in disniprion of smooth
flow. It causes surface disturbance and uneven
surface level, and often masks subsurface areas
` because air bubbles are entrained in the water.
Unravel: To lose material from the edges of
~ a structure, streambank, or hillslope.
~ Unstable Streambank: A bank that is erod-
ing or failing on a regular basis.
Vegetated Geogrid: Soil wrapped with a
~ geotextile fabric and with live woody plant cut-
tings placed in between each soiUgeotextile wrap.
~
Glossary ('r7
~
REFERENCES FOR THIS GLOSSARY .
1
Amencan Society of Civil Engineers. 1962. ~
Nomenclature for Hydraulics. Hydraulics ~
Division of the ASCE.
American Fisheries Society. 1985. Aquatic ~
Habitat Inventory Glossary of Stream
Habitat Terms. AFS Westem Division.
Bates, R.L. and J.A. Jackson, eds. 1984. ,
Dictionary of Geological Terms, 3rd ed.
Anchor Press/Doubleday, Garden City, ~
N.Y. Hunter, C.J. 1991. Better Trout Habitat: A ~
Guide to Stream Restoration and
Management. Island Press, Washington, D.C.
~
Langbein, W.B. and K.T. Iseri. 1960. General
Introduction and Hydrological Definitions. ~
Geological Survey Water-Supply Paper
1541-A. U.S. Department of the Interior.
Meehan, W.R., ed. 1991. Influences of Forest ~
and Rangeland Management on Salmonid
Fishes and Their Habitat. Bethesda, Md. ~
American Fisheries Society. 751 p.
~
~
. ~
~
~
~
G8 Glossary
~
~ t
REFERENCES CITED
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pp_ Colo.
~
Schuster, R.L. and R.J. Krizek. 1978. Smith, D.G. 1976. Effect of Vegetation on
Landslides--Analysis. National Academy Lateral Migration of Anastomosed
~ of Sciences, Special Rpt. 176. Channels of a Glacier Meltwater River.
Transportation Board. National Reseazch Bull. of the Geol. Soc, of Amer. 87: 857-
~ Council. 234 pp. 60. -
Sears, D.E. and L. Mason. 1973. Roadside Snohomish County. 1990. Aquatic Resource
~ Revegetation Program: Located at Colville Protection Program Policy Document,
National Forest. Coeur D'Alene National Attachment C: List of Food Plants.and
Forest Nursery. Progress Report. Their Value to Wildlife. Everett, Wash.
~ Seattle Audubon Society. 1991. A Citizen's Soil Conservation Service. 1973. Soil Survey
Guide to SEPA: How to Participate in the of King County Area, Washington. U.S.
~ Process. Seattle, Wash. Dept. Agriculture.
Sedell, J.R. and R.L. Beschta. 1991. Bringing Sullivan, K., K. Doughty, J.E. Caldwell, and P.
~ Back the "Bio" in Bicengineering. Amer. Knudsen. 1990. Evaluation of Prediction
Fish. Soc. Symposium 10:160-175. Models and Characterizarion of Stream
Temperatures Regimes in Washington.
,i Seehorn, M.E. 1985. Fish Habitat T/F/W Rpt. No. TFW-WQ3-90-006.
Improvement Handbook. U.S. Forest Wash. State Dept. of Natural Resources,
~ Service, Southern Region Tech. Pub. R8- Olympia, Wash..
TP7.
~ References Cited R'7
~
Thorne, C.R. and J. Lewin. 1979. Bank Wazd, B.R. and P.A. Slaney. 1981. Further ~
Processes, Bed Material Movement and Evaluadons of Structures for the
Planform Development in a Meandering Improvement of Salmomd Rearing m
River. In: Rhodes, D.D. and G.P. Coastal Streams of British Columbia. In:
Williams, Adjustments of the Fluvial Hassler, T.J., ed. Proceedings of ,
; System. KendalUHunt Publishing Propagation, Enhancement, and
Company. Dubuque, Iowa. Rehabilitation of Anadromous Salmonid
. Populations and Habitat. Calif. Coop. ~
Trotter, P. C. 1989. Coastal Cutthroat Trout: A Fish. Res. Unit. Humbolt State Univ.,
Life History Compendium. Trans. Amer. Arcata, Calif. ~
Fish. Soc. 118:463-473.
Washington Departrnent of Wildlife. 1992.
U.S. Army Corps of Engineers. 1991. Bull Trout/Dolly Varden Management and ~
Hydraulic Design of F1ood Control Recovery Plan. Fisheries Management
Channels. EM-1110-2-1601. Div. 92-22. Olympia, Wash.
~
U.S. ArmY CoIPs of EnS1 'neers. 1981. Final Washington DepaRment of Wildlife. [no date]
Report to Congress, The Streambank Plants for Wildlife in Western
Erosion Control Evaluation and Washington. ~
Demonstration Act of 1974 Section 32, PL
93-251. Washington State Department of Ecology.
1992. Draft Dam Safety Guidelines--Part
U.S. Forest- Service. 1989. Annotated IV. Water Resources Program. Olympia,
Bibliography on Soil Erosion and Erosion Wash. ~
Control in Sub-arctic and High-latitude
Regions of North America. Pacific Washington State Department of Ecology.
Northwest Research Sta. Gen. Tech. Rpt. 1990. Commonly Required ~
PNW-GTR-253. Environmental Pernuts For Washington
State. 90-29. Olympia, Wash.
U.S. Army Engineer District, Portland. 1980. ~
Willamette River Bank Protection Washington State Depactment of Ecology.
Program. Proposed Revetment 1984. State Environmental Policy Act
Maintenance Categories and Criteria for Rules. Chapter 197-11, Washington ~
Existing Revetments. Portland, Oreg. Administrative Code. Olympia, Wash.
U.S. Army Engineer District, Seattle. 1982. Washington State Department of ~
Vegetation Monitoring Report. Green Transportation. 1991. Standard
River Streambank Protection Specifications for Road, Bridge, and Demonstration Project. Seattle, Wash. Municipal Construction. Olympia, Wash. ~
U.S. Soil Conservation Service. 1986. Wasser, C.H. 1982. Ecology and Culture of
Washington State Supplement to Practice Selected Species Useful in Revegetating ~
Standard 322 Channel Vegetation. Disturbed Lands in the West. U.S. Dept.
of the Interior, Fish and Wildlife Service.
Van Dersal, W.R. 1938. Native Woody Plants FWS/OBS-82/56. 347pp. ~
of the United States, Their Erosion Control
and Wildlife Values. U.S. Dept. of ~
Agricultural, Misc. publ. 303.
R-8 ReFerences Cited ~
~
Weaver, W.E. and M.A. Madej. 1981. Erosion
~ Control Techniques Used in Redwood
National Park. In: Davies, T.R.H. and
A.J. Pearce, eds. Erosion and Sediment
~ Transport in Pacific Rim Steeplands.
Washington D.C. Int'1 Assoc.
~ Hydrological Sciences: 640-654. IAHS-
AISH Pub. 132.
~ Wesche, T.A. 1985. Stream Channel
Modifications and Reclamation Structures
to Enchance Fish Habitat. In: Gore, G.A.,
~ ed. The Restoration of Rivers and
Streams. Chap. 5. Butterworth Publishers.
Boston, Mass. ~ Whitlow, T.H. and R.V. Harris. 1979. Flood
Tolerance in Plants: A State-of-the-Art
~ Review. Tech. Rpt. E-79-2. U.S. Army
Corps of Engrs. Waterways Exp. Sta.,
~ Vicksburg, Miss.
Wittler, R.J. and S.R. Abt. 1990. The Influence
of Uniformity on Riprap Stability. In:
~ Chang, H.H. and J.C. Hill, eds. Hydraulic
Engineering. Volume 1. Hydraulics
~ Division of the Amer. Soc. of Engrs.
Proceedings of the 1990 National
Conference, San Diego, Calif.
~ Woods, J.B. 1938. Ligneous Plants for Erosion
Control. Masters Thesis. Univ. Wash.
~ Seattle, Wash.
Wydoski, R.S. and R.R. Whitney. 1979. Inland
~ Fishes of Washington. Univ. of Wash.
Press. Seattle, Wash.
Ziemer, R.R. 1981. Roots and the Stability of
Forested Slopes. In: Davies, T.R.H. and
A.J. Pearce, eds. Erosion and Sediment
~ Transport in Pacific Rim Steeplands.
~
~
~ ReFerences Ciied R"9
~
~
1
I
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~ ~
~
l
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~
. ~
~
~
~
~
~
~ ~
~
~
~ APPEND/X A `
~ A BRIEf DESCRIPTION OF MA10R RIVER SYSTEMS IN KING COUNTY WITH NOTES ON
FISH UTIIJZATION AND SALMONID HABITAT REQUIREMENTS
~This appendix discusses the characteristics of the rivers within each of the four designated Water
Resource Inventory Areas (WRIA) in King County. The following material was compiled from the State
~ of Washington Water Resource Inventory and Washington Department of Fisheries Catalog of
Washington Streams and Salmon Utilization, Volume 1, Puget Sound Region (Williams et al. 1975).
~ Addirional information was included from Region IV of the Washington Department of Wildlife
(WDW) and numerous local sources. Also included in this appendix is a discussion of the salmonid
habitat requirements and use in large streams and rivers.
~
WATER RESOURCE INVENTORY AREAS
~
The streams of King County are cataloged in four Water Resource Inventory Areas (WRIA)• 'I'hese
~ are (Flgure A.1):
- Snohomish Basin (WRIA 07). This includes that portion of the South Fork Skykomish River and
~ its tributaries in King County, plus the Snoqualmie River system.
- Lake Washington Basin (WRIA 08) consists of the Sammamish River system, Cedaz River
~ system, and eight smaller streams that enter Lake Washington independently.
- Duwamish Basin (WRIA 09) includes the Green-Duwamish River and five smaller drainages that
enter Puget Sound independently.
- Puyallup Basin (WRIA 10). Includes reaches of the White River and its tributaries, including the
nwater River, in Kin S Count Y, an d that portion of HYlebos Creek .in King County.
~ Gree
~
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~
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A-2 AppendiX A ~
~ . . ~
SOUTH FORK SKYKOMISH RNER DRAINAGE (WRIA 07)
~
Description
South Fork Skykom'sh River origi nates in the rugged, forested, steeP1Y sloPed country of the high
~
~
Cascade Mountains. Formed by the confluence of the Tye and Foss Rivers 11 miles below Stevens Pass,
~ it flows generally west and northwest across the northeastern corner of King County past the community
of Baring where it enters Snohomish County. Its principal tributaries in King County are the Miller,
Beckler, and Foss Rivers, plus Money and Index Creeks. These are all moderate size tributaries with
~ significant populations of. resident and anadromous fish. These upper drainages have mountain
characteristics including moderately steep gradient and extensive large rock and cascade areas with
~ considerable pool and riffle areas sufficient to sustain good populations of fish. Altogether, this system
accounts for 4541inear miles of stream in King County.
~ahon
~ Fish Util' '
I Historically, none of the King County portion of the South Fork Skykomish drainage supported
anadromous fish. In a 2.5 mile reach beginning about two miles downstream from the King-Snohomish
county line, the South Fork Skykomish flows over three major falls: Eagle Falls (28-foot drop), Canyon
~ Falls (48-foot drop), and Sunset Falls (88-foot drop). This complex formed a natural barrier to upstream
migration that prevented anadromous fish from reaching the King County portion of the drainage. After
a fishway trap-and-haul facility was constructed at Sunset Falls in the late 19512's, anadromous fish were
! introduced to the upper drainage. As a result, an excellent fishery for large resident rainbow trout (fish
up to 17 inches reported by locals) was largely displaced as the number of anadromous fish increased.
The South Fork Skykomish system in King County is now used by spring and fall chinook and coho
salmon, and by summer and winter steelhead. This reach also has resident rainbow and cutthroat trout,
although not in the numbers and size range once reported. Whitefish are also present, and perhaps a few
~ Dolly Varden char. Adult chinook, coho salmon and steelhead ascend the drainage as far as Alpine Falls
on the Tye River; chinook salmon and steelhead spawn mosdy in mainstem reaches throughout the
system. Coho use every accessible stream and tributary, including the lowermost reaches of the small,
~ steep tributaries high in the drainage. Juvenile fish reaz throughout these accessible waters.
~ SNOQUALMIE RIVER DRAINAGE (WRIA 07)
~ Description .
~ South Fork Snoqualmie River begins near Snoqualmie Pass and flows generally northwest for 35
miles to Snoqualmie Falls. It flows mosdy through mountainous terrain with steep gradients and many
cascade areas and falls. There are, however, extensive good quality pool-riffle sequences in the lower
~ reaches where the gradient becomes less steep. Together with its short, mosdy steep mountain tributaries,
the South Fork Snoqualmie accounts for 1121inear stream miles in King County. The river is paralleled
in areas by the I-90 freeway.
~
~ Appendix A A-3
F ~
Middle Fork Snoqualmie River starts in the Mt. Daniel-Mt. Roosevelt-Big Snow Mountain area
of the high Cascades and flows west and southwest 40 miles to its confluence with the North Fork five ~
miles upstream of Snoqualmie Falls. Principal tributaries are the Taylor and Pratt Rivers, Burntboot,
Dingford, Cripple, and Granite Creeks. The upper 10 miles of river flows through a very narrow valley
with steep mountain side slopes. Although the slopes remain steep, the valley broadens and narrows ~
intermittently through the next nine miles, then broadens more and slopes gently back to steeper hillsides.
Near North Bend, the valley becomes quite broad and flat. In the headwater region, the stream flows
swiftly within a confined channel over mosdy a steep gradient with numerous cascades and high gradient ~
riffles. The gradient then moderates for about 19 miles. Here the channel offers a good pool-riffle balance
with numerous broad, lengthy riffles and several deep pools. Thegradient steepens again in the next eight ~
miles with areas of riffles and low cascades separated by large pools. The lower four miles have a
moderate to gentle gradient with good pool-riffle balance and many broad low gradient riffles. Both the
Pratt and Taylor Rivers contain lengthy reaches with moderate gradients and good pool-riffle balance ~
with gravel-rubble bottom substrates. Most other tributaries have steep mountainous characteristics with
numerous cascades and limited pools and riffles. Altogether, the Middle Fork system accounts for 240
linear stream miles in King County. ~
North Fork Snoqualmie River originates in the Lennox Mountain area of the high Cascades and
flows 26 miles to its confluence with the Middle Fork. The combined Middle and North Forks join the ~
South Fork about five miles upstream of Snoqualmie Falls. Principal tributaries are Lennox, Sunday,
Deep, Calligan, and Hancock Creeks. The upper six miles of the North Fork have steep mountainous
characteristics with a narrow valley, steep slopes, and high stream gradient with numerous cascades and ~
high gradient riffles and few pools. In the seven miles downstream from L.ennox Creek, the valley is
broad, flat, and covered with mainly deciduous vegetation. The gradient here is gentle to moderate, and
the channel exhibits considerable splitting. There are numerous pools and many long, slow glides in this ~
reach. Gradient is moderate over the next eight miles with a few low cascades, but overall good pool-
riffle conditions. Downstream from Hancock Creek, the river enters a ravine and flows over a series of
cascades, some exceeding four feet. The stream here is narrowly confined with numerous high gradient ~
riffles separated by pools. Upon exiting the gorge, the gradient moderates and the stream exhibits good
pool-riffle balance with gravel-rubble bottom. Most North Fork tributaries are steep, with many cascades
and high gradient riffles. Deep and Sunday Creeks have lengthy reaches of moderate gradient and good ~
pool-riffle sections with gravel-rubble bottoms. Altogether, the North Fork and its tributaries account for
156 linear stream miles in King County. ~
Main Snoqualmie River downstream from the forks flows generally northwest and north to the
King-Snohomish County line just past the town of Duvall. The mainstem and all of its tributaries in this ~
King County reach (not including the forks) account for an additional 309 linear miles of stream.
Principal tributaries are Tokul Creek, Raging River, Tolt River, Griffin Creek, Patterson Creek,
Skunk Creek, Harris Creek, and Ames Creek. The five miles of main Snoqualmie from the forks to ~
Snoqualmie Falls have a moderate gradient with good pool-riffle conditions. Some riprapping has
occurred in this area. Downstream from the falls, the river winds in shallow bends, oxbows, and meanders
across the valley floor. The valley averages 1.5 miles in width with hillsides rising to about 400 ft. Many ~
large side sloughs formed by overflow waters are found mostly on the east side below Fall City: The
gradient is extremely low. While Iong gravel riffles appear in places, especially just downstream of the
Tolt River, the river is mostly slow and slough-like with diked banks and a bottom of heavy mud and silt. ~
Land use is mostly agricultural, although urbanization is rapidly encroaching.
. ~
q.4 _ Appendix A ~
~ Tolt River begins in the Cascade Range, the North Fork neaz Red Mountain and the South Fork near
a divide opposite Money Creek (South Fork Skykomish drainage). The South Fork's upper six to seven
miles are inside the City of Seattle municipal watershed. Flows in the South Fork, and m the mun Tolt
~ below, are controlled by spillway releases from Seattle's water supply reservoir. A large falls just below
Seattle's dam blocks upstream migration of anadromous fish on the South Fork. Downstream from this falls, forits remaining eight miles, the South Fork gradient is moderate to steep with mostly fast riffles
~ and cascades, particularly in a short canyon section about two-thirds of the way down. The substrate is
mainly cobbles and boulders with short gravel riffles and patches. Clearcut logging has been extensive
outside the municipal watershed. The North Fork's upper six miles are steep.with numerous cascades
~ and a few short pool-riffle sequences. The next six miles are moderate gradicnt witti some channel
splitting and a number of good pool-riffle sequences. A three to four mile canyon follows with a steep
gradient and many cascades and high gradient riffles. One falls in this reach exceeds 25 feet and is a~ migration barrier to anadromous fish. Two miles of moderate gradient follow to the confluence with the
South Fork. Downstream from the confluence, the main Tolt flows nine miles to the Snoqualmie River.
. The Tolt River valley begins to widen here and stream gradient gradually decreases. The first four miles
~ of channel are fast riffle in character with a boulder, cobble, and gravel substrate. The lower five miles
contain increasing sections of gravel riffles and generally good pool-riffle balance. Channel splitting and
overflow side channels occur in this reach. Stossel Creek, which is a principal tributary, provides 4.5
~ miles of accessible stream.
~ Raging River originates near the 3000 ft. level on the southwest slope of Rattlesnake Mountain and
flows northwest 10 miles to the town of Preston, then turns northeast for 4.5 miles to its confluence with
the Snoqualmie River at Fall City. Lake Creek and Deep Creek are principal tnbutanes. The upper
reaches of Raging River descend through deep ravines to near the 900 ft. elevation where the gradient
~ moderates. Most of the upper watershed is in second growth timber. In the lower gradient section, there
are good pool-riffle sequences interspersed with large cobble and boulders. Flood control dikes have
~ been conswcted along the lower few miles. Raging River has a reputation for fast runoff and flash
flooding. Mean annual flow is 146 cfs; summer low flows are 9-15 cfs.
~ Fish Utilization
~ There is no natural use of the Snoqualmie system by anadromous fish above Snoqualmie Falls on the
Snoqualmie River or upstream of impassable falls on both the North Fork and South Fork Tolt River.
The Washington Department of Fisheries has planted hatchery propagated salmon above Snoqualmie
~ Falls on occasion in the past and has proposed several times that salmon be introduced into the excellent
"unutilized" habitat above the falls. Use of all areas above impassable bamers by resident rainbow and
cutthroat trout is extensive, especially the three forks of the Snoqualmie River and the two forks of the
Tolt. The Middle Fork Snoyualmie River has been called the finest remaining resident trout fishery on
the west side of the Cascade Mountains.
Downstream from Snoqualmie Falls, the system is used by spring and fall chinook, coho, pink, and
chum salmon, winter and summersteelhead, and searun cutthroat trout. Spring chinook salmon, although
not numerous, spawn in the upper portions of the Snoqualmie and Tolt Rivers. Fall chinook spawn in
~ approximately 11 miles of the main Snoqualmie River above the town of Duvall, and in about 12 rrtiles
of tributary, principaily the Raging and Tolt Rivers and in Tokul and Griffin Creeks. Coho salmon use
virtually every accessible stream and tributary, with major use occurring in the Raging and Tolt Rivers,
~ and in Tokul, Griffin, Harris, Patterson, Ames, Skunk, Lake, and Deep Creeks. Chum salmon use the
~ Appendix A A-5
mainstem Snoqualmie, most intensely in the reach just below the mouth of the Tolt and again below Fall
City. Some chum salmon also spawn in Harris and Ames Creeks. Pink salmon spawn in the same areas
of the mainstem as the chums, and prior to 1975 were also observed in the lower portions of Raging River.
Winter steelhead use primarily mainstem reaches for spawning, although this run is heavily supple- ~
mented from the WDW hatchery on Tokul Creek. While summer steelhead home to the Tolt River for
spawning, they may use the main Snoqualmie in the reach from Tokul Creek to Snoqualmie Falls as a
thermal refuge in the summer (K. Beardslee, Washington Trout, personal communication). The Tolt - ~
River summer steelhead is listed by the American Fisheries Society as at high risk of extinction and may
be petitioned for listing under the U. S. Endangered Species Act. Steelhead are also found in the Raging
River. The extent of searun cutthroat use in the system is not known, but in other river systems these fish ~
use all accessible tributaries in lower gradient reaches.
LAKE WASHINGTON DRAINAGE (WRIA 08) ~
~
Description
This drainage consists of all waters flowing into Lake Washington and thence through Lake Union ~
and the Salmon Bay waterway to Puget Sound at Shilshole Bay. The major components of the drainage
are the Sammamish River complex, the Cedar River, and a group of independent drainages around the ~
north and east sides of Lake Washington.
Prior to 1916, when the government locks and Lake Washington ship canal were completed, this ~
enrire drainage flowed to the Duwamish-Green River drainage (WRIA. 9) via Black River at the south
end of Lake Washington. The Cedar River discharged into Black River immediately downstream from
the lake, which then flowed into the Duwamish River and thence to Puget Sound at Elliott Bay. ~
The Sammamish River complex includes the Sammamish River and its tributaries, Big Bear,
Little Bear, North, and Swamp Creeks, as well as Lake Sammamish and its principal tributaries, ~
Issaquah Creek, Tibbets Creek, and Laughing Jacob Creek.
Issaquah Creek begins in the moderately steep foothill slopes near Hobart and meanders generally ~
north to Lake Sammamish. It provides the greatest amount of good pool-riffle area of any of the Lake
Sammamish tributaries. Cleared farmlands and intermittent deciduous groves border the stream with
urban development occurring in many areas. While Tibbets and Laughing Jacob Creeks are similar in ~
characteristics to Issaquah Creek, their accessible lengths are shoRer. Again, urbanization of these
watersheds has intensified in recent years.
Sammamish River runs north and west from Lake Sammamish 12 miles to Lake Washington. Its ~
entire length was channelized for flood control in 1964. Flow is sluggish and the bottom is heavily silted
and infested with milfoil. Big Bear Creek,12.5 miles long, originating in Paradise Valley, lies in a flat ~
valley about a mile in width. The stream gradient is gentle and the unaltered reaches have abundant pool-
riffle-glide areas, with excellent gravel above the York Road crossing at Avondale. Bear Creek has
several tributaries: Evans Creek, Mackey Creek, Cottage Lake Creek, Seidel Creek, and Struve ~
Creek. The entire Bear Creek watershed is experiencing intense urbanization, as are those of Swamp,
North, and Little Bear Creeks which all lie in close proximity to one another in the lower six-mile
section of Sammamish River. These are typical lowland streams flowing from gende hillsides and ~
A-6 Appendix A ~
gradually meandering through rolling hills, wetland areas, and bottomlands. The small farms and
~ pasturelands that once were prevalent have given way to urbanization (residential developments, large
shopping centers, and the like). Swarnp Creek has been channelized in the lower two miles above
~ Kenmore. Cedar River originates in high mountain country near Stampede Pass and flows west-northwest
~ nearly 50 miles to its present confluence with Lake Washington at Renton. The upper 10 miles flow
through steep-sloped, narrow, forested mountain terrain. In this reach, the river has numerous high
gradient riffles and cascades with few pools or lower gradient riffles. Two water storage reservoirs,
, Chester Morris and Cedar Lake, are in the next nine miles. Downstream from Cedar Lake to the City
of Seattle water diversion dam at Landsburg, a distance of 14 miles, the forested valley is alternately
shallow and broad. The river has many gentle gradient reaches with good pool-riffle areas. The diversion
~ dam is a total banier to upstream migration of anadromous fish. Downstream from the barrier, the river
flows five miles to Maple Valley with several high gradient areas of mostly boulder and only intermittent
areas of good pool-riffle sequences. Downstream from Maple V alley the river meanders over a shallow,
~ relatively broad valley and the stream takes on good pool-riffle character with excellent spawning and
rearing habitat for fish. The area is increasingly urbanized, and .the lower three miles is heavily
~ industrialized. Tributaries accessible to fish are Rock, Downs and Madsen Creeks.
~ Independent drainages
There are eight independent drainages. At the north end of Lake Washinoon between Sand Point
and Kirkland are Thornton Creek, McAleer Creek, Lyons Creek, and Juanita Creek. Thornton,
~ McAleer and Lyons Creeks are all relatively short (four to seven miles), lowland streams originating in
broad valleys at the 300-400 foot elevation then narrowing to more confined ravines in the lower reaches.
~ Juanita Creek,14 miles long, flows south from Norway Hill south of Bothell to Juanita Bay through an
area of heavy development. Juanita Creek is a low gradient stream, but its tributaries are steep and
contain falls. Juanita Creek substrate is pea gravel, sand and silt with larger gravels through the lower
~ reaches. Along the east shore of Lake Washington are Mercer Slough, Coal Creek, May Creek, and
one unnamed stream. Mercer Slough is formed by Kelsey Creek, which heads at L,arsen Lake in Lake
Hills and flows 4.6 miles through a concentrated industrial, business, and residential area. Sturtevant
~ Creek, which originates at Sturtevant Lake in Bellevue and flows 1.3 miles also through intense
- development. Coal Creek flows seven miles from the Newport Hills-Newcastle area through a steep
ravine with several impassable falls. This stream passes through a 457-foot culvert at Highway 405. May
~ Creek originates at Lake Kathleen and flows west 8.6 miles to Lake Washington through a mostly
urbanized watershed.
~
Fish Utilization
~ Chinook, coho, and sockeye salmon use the Lake Washington drainage, as do steelhead, searun
cutthroat trout, and resident races of rainbow and cutthroat trout and whitefish. Fall chinook salmon use
~ much of the accessible stream length of the Cedar River and larger Lake Sammamish tributaries
including Issaquah Creek and Big Bear Creek. Coho salmon use virtually all accessible streams
including Cedar River and its tributaries, Sammamish River tributaries, Lake Sammamish tnbutanes,
~ and each of the eight independent Lake Wa.shington drainages. While adult sockeye salmon principally
use the Cedar River and its tributaries plus the Issaquah Creek and Big Bear Creek drainages for
~ Appendix A A-7
spawning, some spawning has occurred in all of the accessible streams of the Lake Washington drainage.
In addition, some sockeye spawning occurs along Lake Washington and Lake Sammamish beaches. It ,
is worth noting that juvenile coho and chinook salmon as well as sockeye salmon use Lake Washington,
Lake Union, and the Salmon Bay waterway for rearing. While lake rearing is not unusual for sockeye ~
salmon, it may indicate a unique adaptation for stocks of coho and chinook salmon in the Lake
Washington system. Steelhead spawn in the Cedar River and larger tributaries of the Lake Sammamish
system. Although searun cutthroat trout utilization,has been reported and should occur, their use of the ~
system is not well documented. There are also lake-resident cutthroat trout that utilize Lake Washington
tributaries for spawning and rearing, and each system has resident trout populations of varying numerical
strength.
DUWAMISH-GREEN RIVER DRAINAGE (WRIA 09) ~
Description ~
This drainage now consists of one large river system, the Green River, which in its lower 10 miles,
is also known as the Duwamish River. The dual name occurs because prior to 1916, the Green River ~
joined here with the Black River (which then carried the flow of the entire Lake Washington and Cedar
River drainages) to form the Duwamish. The Green-Duwamish River system accounts for over 6431ineal ~
miles of stream in King County. In addition to the Green-Duwanush River, five small independent
drainages also enter Puget Sound. These include Longfellow Creek which enters Elliott Bay near the
mouth of the Duwamish, and Miller, Bow, Lake, Joe's, and one unnamed creek that enter Puget Sound ~
between Alki Point and Dash Point.
Green River heads in the high Cascades on Blowout Mountain about 30 miles northeast of Mt. ~
Rainier, and flows generally west and northwest for 25 miles through mosdy narrow valley, steeply
sloped, forested temain before coming to gentler slopes and broader valleys. In this rugged, moderately
steep-gradient run, the Green River receives tributary flow from Sunday, Sawmill, Champion, Smay, ~
and Charlie Creeks and from the North Fork Green River. Just below the confluence of the North Fork
is Howard Hanson Dam, a flood control facility completed in 1962, and tluee miles below that is the City
of Tacoma water diversion facility, which represents the present upper limit of anadromous fish ~
migration. The upper drainage is managed as a municipal watershed. Downstream from the water
diversion, Green River remains a moderately steep gradient river as it flows another 25 miles through
the Green River Gorge, emerging at Flaming Geyser Park. The upper part of this reach, just downstream ~
from the water diversion, is a boulder zone that lacks gravel recruitment. Downstream from the gorge,
the river meanders for about 10 miles over a broad valley floor largely agricultural in character. Important
tributries in this reach aze Newaukum, Crisp, Burns, and Soos Creeks. The river continues to meander ~
through a valley where urbanization and industrialization have rapidly replaced former farmland. The
cities of Auburn and Kent are located here. Near Kent, the river gradient diminished considerably and
the remainder of the Green-Duwamish is characterized by slow flows. Here the streambanks have been ~
extensively leveed and channelized. The lower Duwamish has been moved several times since the turn
of the century to accommodate industrialization. ~
The independent drainages are all relatively short and each experiences periods of low or intermittent
flow. Longfellow Creek is a moderate gradient stream over its entire length, but the others flow to the ~
A=8 Appendix A ~
~ •
Sound over steeper terrain and have only limited areas near their mouths which are accessible to
~ anadromous fish. ,
~ Fish Utilization
Spring and fall chinook and coho salmon, steelhead, and searun cutthroat trout use the Green-
~ Duwamish basin. Anadromous Dolly Varden char have also been reported. Odd-year runs of pink
salmon that once used the Green-Duwamish basin have been extinct since the mid-1930's. Although
chum salmon also used this system, all recent escapement counts of wild fish have been zero and the wild
~ stock is probably now extinct. Hatchery chum salmon are now released from the Soos Creek hatchery.
The system is also utilized by resident stocks of rainbow and cutthroat trout and by whitefish. The City
of Tacoma water diversion facility represents the present upper limit of anadromous fish migration in
~ the system. A trap and haul operation has been established to pass anadromous salmonids upstream of
Howard Hansen Dam. ~ The independent Puget Sound drainages within this WRIA are or were used to some extent by coho
and chum salmon and searun cutthroat trout, but the magnitude of present use is unknown.
~
WHITE RIVER DRAINAGE (WRIA 10)
~
Description
~ White River originates from Emmons Glacier on the northeast face of Mt. Rainier and flows north
more than 25 miles to Greenwater, where it forms a poRion of the southern boundary of King County.
~ Greenwater River, another part of the southern boundary of King County, begins on Castle Mountain
north of Naches Pass and flows generally northwest for 21 miles to its confluence with the White River.
From the town of Greenwater, the White River flows west for 22 miles toward Enumclaw, loops north
~ toward Auburn, then turns south again to exit King County and join the Puyallup River at Sumner. In
this reach, the river is also known as the Stuck River. Historically, the White River switched drainages
from time to time in this section. Prior to 1906, the river flowed around the southeast edge of Auburn into
~ the Green River. In 1906, a flood diverted the stream south into the Puyallup, a situation that was made
permanent in 1915 when a dike was built across the old Stuck River channel.
~ Greenwater River drops rapidly from its headwaters through a steep, narrow, forested valley, over
numerous cascades and a predominately bedrock and boulder stream bottom. Downstream from Burns
Creek, a principal tributary in this upper reach, the gradient decreases to moderate and the channel takes
~ a more winding course to Greenwater. Although ihe channel remains confined, it has several channel
splits and a good pool-riffle ratio. Streambanks are generally stable, consisting of earth or rock cuts or
~ gravel-cobble beaches. The watershed has been extensively logged.
White River is a swift moving, glacial stream that carries a heavy load of silt from the Emmons
~ Glacier. Downstream from Greenwater, its streambed consists of boulders, cobble, and large gravel.
Sixteen miles downstream from Greenwater is Mud Mountain Dam, a flood control structure with a
narrow, four-mile reservoir. Principal King County tributaries in this reach are Clay Creek, Cyclone
~ Creek, West Twin and East Twin Creeks. Downstream from Mud Mountain Dam, the river channel
Appendix A A-9
~
. t
is confined in a nazrow, steep-sided canyon for three miles before the valley widens. Principal King
County tributaries in this reach are Boise Creek and Red Creek. Boise Creek, approximately six miles '
in length, originates upstream of a Weyerhaeuser sawmill complex and flows through an almost 1000
ft. culvert under the mill, then through a well-defined channel cut deeply in the largely agricultural
plateau. It contains good gravel and has a good pool-riffle ratio. Approximately five miles downstream ~
from Mud Mountain Dam, Puget Sound Power & Light Company diverts water from the White River
into Lake Tapps. Discharge from Lake Tapps returns to the White River near Sumner in Pierce County.
The river downstream from Enumclaw meanders across a broad valley to Auburn and contains ~
increasing amounts of reasonably good spawning and rearing habitat. However, the stream does
transport heavy silt loads from an annual flushing operation at Mud Mountain Dam and the water
diversion operation. ~
East Fork Hylebos Creek originates at Lake Killarney about four miles north of the King County ~
line northeast of Federal Way. West Fork Hylebos Creek heads in the new City of Federal Way near
the Sea-Tac Mall. T'he two forks flow south and join near the King County line, where the mamstem turns west, and flows into the Hylebos Waterway and Commencement Bay.
~
Fish Utilization ~
Utilization of the lower 20 miles of White River is mostly for migration and perhaps freshwater
rearing of juvenile fish, although some chinook, chum and pink salmon spawning occurs in reaches ~
upstream to the PP & L water diversion. While this diversion is a total blockage to upstream migration
of anadromous 'fish, a trap and haul operation transports fish above Mud Mountain Dam where they are
typically released near Greenwater to spawn and rear in the upper watershed. Coho salmon udlize all ~
accessible areas of Boise Creek, and chum salmon spawn in its lower mile. Resident trout are also present
in Boise Creek. Chinook salmon and steelhead use the upper White River, and coho salmon ascend all
accessible tributaries. The Greenwater River upstream as far as Burns Creek served as one of the ~
principal spawning areas for spring chinook salmon in the White River drainage; this run is now at high
risk of extinction and all returning adults are trapped for captive breeding and rearing. Steelhead, coho,
and resident trout also use the Greenwater River. ~
Hylebos Creek is utilized by coho and chum salmon, and perhaps also by searun and resident
cutthroat trout. Present use is adversely affected by industrialization and heavy pollution in Hylebos ~
Waterway and lower Commencement Bay, and the extensive development activity presently occurring
in Federal Way area.
~
SALMONID HABITAT REQUIREMENTS AND USE IN LARGE STREAMS AND ~
RIVERS
Upstream Migration of Adults ~
In this stage of the salmonid life-cycle, streams serve mainly as corridors along which fish pass to
reach spawning areas. Most salmonids migrate during intermediate streamflows. While high flows may ~
exceed the swimming abilities of the fish, excessively low flows and shallow water depth may block
migration. ~
A-10 '°'ppend"` A
~
r
The ability of adult salmonids to pass obstructions is often underestimated. Given suitable
~ conditions, upstream-migrating salmonids pass many obstacles that appear to be barriers. Many falls that
are impassable under one set of flow conditions may be readily passed when flows change. Larger species
such as chinook, coho, and steelhead have commonly been observed leaping obstacles six to nine feet
~ in height (Stuart 1962), whereas barriers exceeding 4.5 feet can be an impediment for smaller species
and for chum salmon, which are sometimes stymied by obstacles other salmonids pass with ease (Everest
et al. 1985). -
Other impediments to upstream migration include unfavorable water temperatures, high turbidity,
~
and poor water quality. Generally speaking, water temperatures in the range of 30 to 200 C(38° to 680 F)
, are acceptable to fish during spawning migrations. Because most anadromous stocks have evolved with
the temperature patterns of their home streams, significant abrupt deviations from normal patterns can
stop migration and adversely affect fish survival (Bell 1986; Bjornn and Reiser 1991). Migrating
salmonids also cease to migrate in waters with high silt loads (Cordone and Kelley 1961; Bell 1986).
Turbid water also absorbs more radiation than clear water and ttius may promote a thermal barrier to
migration (Reiser and Bjomn 1979). Reduced dissolved oxygen concentrations can disrupt or prevent
~ migration by adversely affecting the swimming performance of the fish, or by eliciting an avoidance
reacdon.
~
Spawning
I Pacific salmonids seek out areas in streams where gravels of suitable size, permeability, and stability
have been deposited. While these areas are typically found in :ransition zone! between pools and riffles
~ (tailouts of pools), suitable spawning areas may also be found in secondary channels, along channel
margins in large rivers, and in the inlets and outlets of lakes. Each species has its own preferences. Pink
and chum salmon usually choose areas not far upstream of saltwater, chinook salmon and steelhead select
~ sites in the mainstem or more robust tributaries, coho salmon and searun cutthroat trout seek smaller
tributaries off the mainstem, sockeye salmon prefer mainstem rivers or lake inlets or outlets, and Dolly
V arden and bull trout head for the highest, coldest tributaries. Each species also has its own preference
~ for size range of gravels, velocity, and depth of water.
Water temperature is also an important factor. Each stock appears to have a unique time and
~ temperature for spawning that maximizes the survival of the offspring in that particular situation. In the
case of fall spawners, for example, newly spawned embryos must reach a critical stage of development
before the water becomes too cold. Also, fry emergence must occur at a suitable time the following
~ spring. For spring spawners, spawning must not occur before the water has warmed sufficiently for
normal development of the embryos. If the temperature suddenly drops again, spawning activity may
~ cease.
The amount of space required per spawning pair depends on the size and behavior of the fish, and
~ on the amount and quality of available substrate. Redds generally range in size from five to more than
nine square -feet for anadromous -salmonids, and from one to eight square feet for smaller non-
anadromous salmonids. The area suitable for spawning (defined by depth, velocity, substrate size, and
~ other intangibles) is usually much less than the total area of gravel substrate in a stream.
~
Appendix A A-1 1
~
. ~ ~
Incubation
Incubation and spawning are inextricably linked, not just because adult fish deposit eggs in fixed ~
locations, but also because selection of the spawning site fixes the incubation environment. During redd
construction and spawning, fine sediments and organic matter within the substrate are swept out and ~
washed away downstream, leaving the redd environment as favorable for the embryos immediately after
construction as it will ever be. From this point on, sufficient water must circulate throughout the egg
pocket to supply the embryos with oxygen and to cany away waste products. Permeability and the ,
apparent velocity of water through the redd are commonly used measures of the suitability of the redd
to support incubation. If either of these parameters decreases, embryo survival also decreases. Both
parameters are reduced by subsequent deposition of fine sediment. Although the redd substrate must ~
remain permeable enough to support complete development of the embryos, it must not be so loose and
unstable as to give way in high flows. ~
Water quality and temperature are also important. While embryos may survive when oxygen levels
are below saturation, development is retarded. Within-gravel, oxygen concentrations depend on many ~
factors: water temperature, surface and intragravel water exchange, apparent velocity of water in the
redd, substrate permeability, and the demand for oxygen of any organic matter either already present or
transported into the redd. Water temperature affects the rate of embryo and alevin deveIopment (as ~
explained above) and also the solubility of oxygen in water (the higher the temperature, the lower the
concentration of oxygen).
~
Emergence and Fry Dispersal
Some juvenile salmonids, specifically pink and chum salmon, do not rear in freshwater but move ~
quickly to saltwater upon emergence. Juveniles of most salmonid species, however, must quickly find
habitat suited to their small size. Because of their small size, young salmon and trout cannot maintain ~
feeding stations in even moderately flowing water (velocities greater than 0.25 feedsec can easily move
these fish downstream). Recendy emerged fry need to find refuge from high flows and predators, and
locations that provide access to small items of drifting food. They find such places along the stream ~
margins in small eddies, and in protected backwaters and secondary channel pools.
Shortly after emergence there is often a general movement of fry downstream that spreads the ~
population within the drainage. These small fish will occupy suitable habitat as they encounter it.
Because of their small size and limited swimming ability, they cannot easily ascend steeper tributaries. ~
Habitat types colonized during this process include stream margins, secondary channel systems, very
low gradient tributaries, and sloughs.
~
Summer Rearing
As the season progresses and they become larger, young fish move to stations away from the channel ,
margins to areas with more and larger food items where they establish and defend territories against
intruders. Each species has its own stream reach and habitat unit preferences for territory establishment. ~
While each species occupies its own niche, differential habitat use may be forced in some cases by
competitive displacement of one species by another. .
~
A-12 Appendix A ~
r ~
The availability of food and the availability of space define territory size. While territories need to
' be large enough to include adequate space, food, and areas for resting and hiding, each individual fish
ultimately determines the size of territory it needs. The more sites that are available, the more fish the
~ reach can accommodate
Cover, in the form of a boulder, cobble, log, or even turbulent water or bubbles, provides the fish with
~ haven from predators and competitors. The type of cover sought, and the way it is used, varies among
salmonid species and also with the age of the fish. Young fish occupy relatively shallow, slow-moving
water in areas closer to overhead cover than do older fish. As they age, individuals of some species, such
~ as Dolly Varden and bull trout, seek out calmer, deeper water where they orient themselves very closely
with the bottom substrate and undercut banks. Coho salmon prefer slower pools, as do cutthroat trout
when they are the sole salmotid in the reach. By contrast, juvenile steelhead and rainbow trout seek out
~ the swifter areas to establish their territories. Rainbow and cutthroat trout, while still remaining near
objects, will assume foraging sites well above the substrate. Salmonids seem to feel most secure when
they can neither see nor be seen by other fish. Logs, boulders, cobble, large debris, or topography of the
~ streambed anything that can screen fish from one another's view-divides a stream into territories that
individual fish may occupy. This visual isolation factor can also influence the size and number of
territories a stream reach can support. A diverse topography provides more and smaller territories than
~ less rough areas (Kalleberg 1958).
Water temperatures also influence the summer rearing of juvenile salmonids. Summer temperatures
i may exceed physiological stress thresholds, and, occasionally, lethal levels. To cope with high
temperatures, salmonids may temporarily use cool-water refuges typically associated with groundwater
~ inputs, subgravel streamflow, or the mouths of cool tributaries.
Overwintering
~ Productive summer rearing locations may not be suitable for overwintering. Metabolism and acrivity
of salmonids slow as water temperatures decline. With the onset of winter, appetites diminish and
~ behavior has less to do with obtaining food and defending foraging sites than with securing refuge.
Territoriality typically breaks down at this time. Death or injury in winter can result from rapid and
catastrophic changes in flow - not only high flows, but low flows as well during extreme cold spells.
~ Overwintering salmonids move into deeper water than they inhabit in summer, and into habitats
characterized by low water velocities. They seek out upturned tree roots, logs, cutbanks and debris, often
in side channels, wetlands, ponds, and slQUghs off the main channel. Younger fish often seek shelter
t under or very close to small cobble. Because the number of fish that salmonid-producing streams can
harbor in winter may be limited by the availability of winter habitat, watershed management projects
should carefully consider the overwintering needs of juvenile and adult salmonids and work toward
meeting these needs.
~ Smolt Migration ,
At the onset of the physiological change that prepares juvenile fish for life in saltwater, territorial
behavior again breaks down and the fish often congregate in schools in large pools. As these changes
~ progress, the smolts begin to move downstream, passively, traveling mostly at night, relying on the
streamflow to carry them to saltwater. Cover along channel margins (e.g., woody debris, interstices
~ among boulders) provide protection for smolts during daylight hours. _
~ Appendix A A-13
~ i
~
~
~
~
~
~
~
~
~
~
~
~
i
~
~ ~
~
~
1
APPENDIX 8 ~
AGENCY AND TRIBAL CONTACTS
1
The following list of addresses and telephone numbers are for regulatory agencies in the King County
~ region.
' KING COUNTY Department of Development and
~ Environmental Services (DDES)
3600 - 136th Place SE
~ Bellewe, Washington 98006
Land Use Services Division (LUSD)
Grading Unit (206) 296-6610
~ Shorelines (206) 296-6650
Sensitive Area Review (206) 296-6660 .
. Technical Services Section (206) 296-6660
~
Environmental Division (ED)
~ SEPA Center (206) 296-6662.
! STATE OF WASHINGTON
Department of Ecology (Ecology)
~ Headquarters Office (206) 459-6000 .
Mail Stop PV-11
Olympia, Washington 98504-8711
~ Northwest Re 'onal Office (206) 867-7000
~
4350 - 150th Avenue NE
r Redmond, Washington 98502-5301
Permits and Coordination Unit (206) 438-7514
~ Mail Stop PV-11
Post Office Box 47703
~ Olympia, Washington 98504 ,
~
~
Appendix B
& 1
STATE OF WASHINGTON, continued
nt of Fisheries '
Departrne (WDF)
Habitat Management Division (206) 902-2534
1111 Washington Street Southeast t
Post Office Box 43155
Olympia, Washington 98504-3155 ,
Emergency Hotline (206) 902-2537
Department of Natural Resources (DNR) ~
South Puget Sound Region . (206) 825-1631 ~
28329 Southeast 448th Street
Post Office Box 68
Enumclaw, Washington 98022 ~
Aquatic Lands Management Division (206) 902-1100
John A. Cherberg Building, QW-21 ~
Olympia, Washington 98504
Depattment of Wildlife (WDW) ~
Headquarters Office (206) 753-5700
600 Capitol Way North ~
Olympia, Washington 98501
Mill Creek - Region No. 4 (206) 775-1311 ~
16018 Mill Creek Boulevard
Mill Creek, Washington 98012
'
FEDERAL ~
U.S. Army Corps of Engineers (Corps)
Seattle District Office ~
Regulatory Branch (206) 764-3495
4735 East Marginal Way
Post Office Box C-3755
Seattle, Washington 98124
Environmental Protection Agency (EPA) ~
1200 Sixth Avenue
Seattle, Washington 98101 ~
Technical Services (206) 553-1296
Water Programs (206) 553-1014
~
B-2 Appe"d"` B ~
FEDERAL, continued
~
U.S. Fish and Wildlife Service (FWS)
Division of Law Enforcement (206) 553-5543
, 121 - 107th Avenue NE .
Bellevue, Washington 98004
~
Federal Emergency Management Agency (FEMA)
' Region X (206) 487-4678
Flood Insurance Program
, Natural and Technological Hazards Programs
130 - 228th Street SW
Bothell, Washington 98021
~ National Marine Fisheries Service (NMFS)
~ Northwest Region (206) 526-6150
7600 Sand Point Way NE
~ Seattle, Washington 98115
~ TRIBES
Muckleshoot Indian Tribe
~ Planning Office (206) 939-3311
39015 - 172nd Avenue SE
~ Auburn, Washington 98002 .
Puyallup Tribe of Indians
Puyallup Tribal Fistieries Division (206) 597-6374
. 2002 East 28th Street (206) 597-6252
~ Tacoma, Washington 98404 (206) 597-6200
Snoqualmie Tribe (206)333-6551
~ P.O. Box 280
3946 Tolt Avenue
Carnation, Washin,gton- 98014
~
The Tulalip Tribes
, Tulalip Fisheries Depaitment (206) 653-0220
6700 Totem Beach Road (206) 653-4585
~ Marysville, Washington 98270-9694
~ Append;,c g 6-3
r
.
~
~
~
t
~
_ ~
~
~
~
~
~
~
~
r
~
~ ~
~
APPENDIX C ~
METHODS FOR RIPRAP DESIGN
1 .
Sizing riprap is complicated by the wide range of variability in river channel characteristics. Because
~ of this variability, designers often resort to simple equations and nomographs. Typically these methods
use an average water velocity as the main criterion. There are limitations with this approach. A velocity-
only method does not account for other river chazacteristics, such as flow depth, that influence rock size.
~ Another factor is that the velocities used in these approaches represent the average velocity across the
cross-section.
~ Bank erosion is a function of the tractive force, which involves flow depth and velocity, and the
characteristics of the flow immediately adjacent to the streambank. The velocities typically used for
design purposes are often computed using one-dimensional analytical techniques such as HEC-2. A one-
, dimensional analysis, however, dces not account for flow variations across the width of the channel, or
for local hydraulic phenomena such as helical flow at the outside of bends. These factors, which are often
~ not quantified in the design technique, are usually left to the judgement of the. designer.
Based on the level of experience of the designer and the complexities of the site, the computed size
of the rock is frequently rounded up to the next standard class as a factor of safety. King County's Surface
~ Water Design Manual (1990), for example, provides specific procedures and a nomograph, developed
by the U.S. Army Corps of Engineers (Corps), for computing the median stone size based on flow
~ velocity. The manual then cautions the user that, "If the rip rap [specified using this methodology] is to
be used in a highly turbulent zone...the median stone should be increased from 200 to 600 percent
depending on the severity of the locally high turbulence." Depending on the designer's judgement, an
~ extremely high variance in the design size of the rock may result.
An additional complication exists in that the computed rock size (usually specified in terms of the
' median stone size or Do dces not always precisely match riprap classifications (e.g., light loose riprap).
King County commonly uses two classes of riprap: light loose and heavy loose riprap. The classes, taken
from the Washington State Department of Transportation's (WSDOT) specifications, delineate the size
~ range and gradation for each class. In practice, the actual size of rock obtained varies with the quarry from
which it is acquired.
, Placement of the riprap may also effect how well the design specifications are met. In the past, the
County's usual method of placing riprap was to grade the bank, end dump the riprap, then shape the rock
layer with a dragline. The largest material from the delivered gradation was used in the toe section. While
` the concept of placing the largest rock at the tce is valid, it unfortunately reduces the amount of large rock
available for the upper bank. This results in a facing that dces not meet the specifications for either light
~ or heavy loose riprap.
~
~
Appendix C
' . Gl
~ r
RIPRAP SIZING ,
Many agencies have developed various approaches to sizing riprap. These methods should be applied
carefully to western Washington rivers as many of them were derived from laboratory studies and tested ~
in other regions of the country. Three recommended methods for sizing riprap are discussed below. Two
of these methods were developed by the U.S. Army Corps of Engineers. The first method was developed
by Maynord et al. (1989); the second is an updated method, based on the research of Maynord et al., that ~
incorporates a larger number of variables in the operative equations (USACOE 1991). The third method
discussed is that of Richardson, Simons and Julien (1990). For a detailed discussion of these method-
ologies, the reader is referred to the original publications. ~
MAYNORD METHOD ~
Maynord et al. propose using a smgle layer of ripmp on top of a ftlter. In their analysis, failure was
defined as the exposure of the material underlying the riprap. This method does not define a riprap size ~
that will not be removed during the design event, but a gradation that will effectively sort and lock
together so as not to expose the filter layer or natural channel bank. T he ripmp size foun d to b est
characterize the gradation was the D30. It is defined as follows: ~
r
D~ ~ SF * C r Wr )l~ * ( )z.s
s w (gY)o.s
~
Where: ~
Dn = Riprap particle size in feet; n percent of ripmp is finer by weight. This particle size, which
is considered the equivalent spherical diameter, is the common method of specification. ~
Because the rock will not be spherical, the actual dimensions will vary.
Y= Depth of water in feet. '
SF= Factor of safety. Use 1.20.
C= Stability coefficient. For Z= 2 or flatter, use C= 0.30; for 1.5 Z 5 2, ~
use C = 0.6 -0.15*Z.
Z= Channel side slope (horizontal offset for one foot vertical increase). ~
I'a = Specific weight of water. ~
I's = Specific weight of stone.
. ~
V - - Local velocity (fps). If unknown, use 1.5 * V ,,,g
g= Gravitadonal accelerazion (32.2 feet per second squared). t
It is important to note that Maynord et al. use D30 as the characteristic size while other methodologies ~
use D50. From laboratory tests, they found if D30 was used as the characteristic size that the ccefficient
G2 Appendix C ~
' A
C was constant regardless of gradation. To calculate D.50 accurately, this coefficient must be varied as it
, depends on the gradation used.
The acceptable range of gradations meet the following criteria (assumptions lisFed in design equation
~ above.):
1.8D15:5 D85 5 D4.6D15
~ Unfortunately, specifications for Dls, D3o, and D$5 do not correlate well with the rock gradations
commonly used in western Washington. Until revised standards for King County are developed, the
' WSDOT's specifications are the most efficient to use. Listed below are the WSDOT classification for
computing each D30. This listing was derived by comparing WSDOT specifications with gradations
proposed by Maynord et al. and the Corps.
~ For D305 3-inch, use quarry spalls. ` For 3-inch < D30<_ 15-inch, use light loose riprap.
For 15-inch < D30<_ 18-inch, use heavy loose riprap.
~ For D30 > 18-inch, the rock gradadon must be explicitly specified.
~
Maynord et al. assume only a single layer of riprap of thickness Dl00 (with necessary filters).
Qualitatively, there is an inverse relationship between necessary stone size and necessary blanket
~ thickness. Thus, if a thicker riprap blanket is used, then a smaller D30 can be chosen. This approach,
however, may cause movement of more of the smaller rock at the design discharge, and may therefore
~ require more frequent maintenance.
The ability to use vegetative methods such as joint planting is diminished by additional riprap depth.
It is recommended that the stone size be based on the analytical technique developed by Maynord et al.,
' and the blanket then be designed to a thickness of D,00 (i.e., the riprap layer should be as thick as the largest
rock in the sample). For the three standard WSDOT gradations, the blanket thickness should be as
' follows: Quarry spalls, minimum thickness = 8-inch
~ Light loose riprap, minimum thickness = 30-inch
, Heavy loose riprap, minimum thickness = 36-inch
A potential limitation in using this procedure for sizing riprap for King County rivers is that the
, experimental data used in its development were limited to channel slopes of less than two percent and
Froude numbers less than 1.2. For extremely steep rivers with turbulent flow, further analysis and study
may be required. While Maynord et al. did not rule out the application of this method to rivers outside
, these limits, they suggest that care be taken since the user would be extrapolating ratherthan interpolating
from the experimental data.
~ .
~ Appendix C G3
. ~ '
UPDATED CORPS METHODS
~
Additional analysis of the laboratory testing and modeling conducted by Maynord et al. resulted in
updated design equations (USACOE 1991). The basic equation in Maynord et al. was updated as follows: t
rW ~
D30= SF * C S* C v * C T* Y Ih v 12.5
I'S- i`W KIgd
All variables are the same as in the previous equation, with the following additions: ~
Cg = Stability coefficient for incipient failure. Use 0.30 for angular rock; 0.36 for '
• rounded rock.
Cv = Vertical velocity distribution coefficient. Use 1.0 for straight channels, 1.25 for ~
ends of dikes and downstream of concrete channels; and 1.283-0.21og(R/W) for
outside of bends (1 for R/W > 26).
where: ~
R= center-line radius of bend
. W = water surface width . ~
CT = Thickness coefficient. Use 1 for blanket thickness of 1 D100. For other thicknesses,
refer to USACOE (1991) to deternune the ccefficient. ~
K1= Side slope cornection factor ,
= 1- sin24 ,
sin2d)
where: '
_ O= angle of side slope with horizontal
(D = angle of repose of riprap material (normally 400)
This e9uation adds considerable complexity to Maynord et al.'s original method. Perhaps because ~
of this, the Corps suggest a slightly decreased factor of safety of 1.1. This factor should be increased when
unusual characteristics exist such as high potential for impact forces from debris. The safety factor could ~
also be increased to account for other circumstances such as expected inaccuracies in computation of
hydraulic parameters or difficult placements.
• ~
,
~
G4 APPendix C ,
RICHARDSON, SIMONS, AND JULIEN (1990).
~
This method is based on flow velocides and depths, and involves a trial-and-error approach
, beginning with an assumed D50. The designer then uses the nomograph in Figure C.1 to compute the
velocity against the stone. The ratio of the velocity against the riprap, Vg, to the mean channel velocity,
~ Vm, is related to the ratio of the stone diameter, D50, to the flow depth, yo, by the curve in the nomograph.
When the total depth of flow exceeds approximately ten feet, the ratios should be computed using 0.4
of the actual flow depth instead of the depth itself. This will yield a riprap size sufficient throughout the
~ cross section. After defining the velocity against the stone using Figure C.1, the next step is to determine
the D50. This is accomplished using Figure C.2, which is based on both velocity and riprap side slope.
If the Dsa computed in this manner does not agree with that originally assumed, then the process must
~ be repeated. These nomographs assume that the unit weight of the rock is 165 pounds per cubic foot. If
the rock is of a different weight, then the stone size should be corrected using the following equation:
, D1_ 102.5 * D~
50 I' - 62.5
where:
~ S
~ D'50 = actual stone size for unit weight being used
Dso = stone size computed from nomographs
' Design velocities should be increased for installations protecting banks from direct flow impinge-
ments such as at the outside of sharp bends. Richardson, Simons and Julien provide two estiniates of the .
~ necessary increase in velocities. One is from the California Division of Highways, who recommend
doubling the velocity against the stone for sharp bends. The other estimate is from Lane, whose analysis
would require the velocity against the stone to be increased by 22 percent for very sinuous channels. In
~ any case, the velocity should be increased to account for the bend. A factor between 1 and 2 is
recommended, depending on the severity of the attack.
~ Because this method computes the D50 rather than the D30, the correlations to the WSDOT
alassifications differ from those listed previously.
' For D50 4-inch, use quarry spalls
For 4-inch < Dso 22-inch, use light loose riprap
'
For 22-inch < Dso 30-inch, use heavy loose riprap
, For D50 > 30-inch, the rock gradation must be explicidy specified
,
,
, Appendix C C-S
Figure C.1 Nomogroph for determining D., based on vel«iy and flow depth. (From FHV1/A 1967.)
'
'
1.0
~
,
D50 = 50% stone size
0.8 ~
0.6
h ~
a~
W =
~ W
0 3 0.4 ,
W 0
O J .
N ~
0.2 ~
~
0 0.2 0.4 0.6 0.8 1.0 ~
VELOCITY AGAINST STONE V$
AVG. CHANNEL VELOCITY Vm ,
~
,
~
C-6 Appendix C ,
Figure C.2 Nomogroph for deiermining ihe sione size based on velocily and side slope. (From FHWA 1967.)
~
,
STONE WEIGHT IN POUNDS
~ 20 60 600 1000 1500 3000 5000
1 5 1 40 100 200 400 800 2000 4000
26
12:1 or '
' bottom
24
4:1
3:1
~ 22
2:1
~ 20 1 Y2:1
~ 18 1:1
0
~ v 16
W
fA
Q
~ 14 '00-~ oooor
W
~ W
W ~
IL J
Z fA
, N 12 '
~
U
1100
' W 1O .
> For stone weighing
165 Ibs. per cu ft.
~ 8
Adapted from report of subcommittee on
4 slope protection, American Sociery of
Civil Engineers Proc., June 1948.
2
,
0 1 2 3 4
I' EQUIVALENT SPHERICAL DIAMETER OF STONE MI FEET
i
'
' Appendix C C'7
'
FILTER DESIGN ~
While the King County Surface Water Design Manual allows the use of a filter fabric, it does not ~
specify fabric selection. The manual provides criteria for design and evaluation of filter material (well-
graded gravel) under riprap. A set of relationships, listed below, has been established for analyzing the
adequacy of the material interface between the armor layer and the protected material underneath. For '
large riprap such as heavy loose, a filter layer will generally be necessary. If the natural channel banks
consist of a fine alluvium, it may be advantageous to place a filter fabric, then a rock filter layer, and
finally the riprap itself. The Surface Water Design Manual does not specify the filter blanket thickness. '
In practice, a well-graded 8-inch thick layer of quarry spalls and smaller material should work well as
a filter layer for light or heavy loose riprap .
The relationships themselves are useful when increased precision is desired. To use these relation- '
ships, analyze the interface between the natural bank material and the armor layer to be utilized. If the
relationships are not satisfied, a filter layer (or layers) must be added so that they hold true across each
material interface. The relationships are as follows: ,
Dls 5 5 d85 ~
4 dls Dls 5 20 d1s
D505 25 d5o ~
where: ~ .
Dn = Armor-layer particle size; (n percent of armor layer material is finer by weight.)
dn = Protected or filter layer particle size; (n percent of protected layer material is finer by ~
weight.)
~
SPECIAL CASES
When the practice of placing the largest rock of the gradation at the toe results in smaller than
,
specified rock for the face, the designer can order 80 percent of the rock using one of the usual
classifications, and the other 20 percent as sorted, large rock (often known as "rockery rock"). This toe '
rock would then be of fairly uniform gradation, computed to be large enough to withstand expected
erosive forces, while the face of the structure would sdll have stone that meets the desired specifications.
The large sorted rock would tend to be more expensive, but using it for only 20°l0 of the overall project '
would limit the increase in costs.
The riprap design methods discussed above may not be appropriate for sizing riprap used in '
combination with lazge woody debris in the toe section of the bank to provide cover for fish. Rather than
cable the root wads or logs into the bank, they can be anchored with large individually placed rocks. A
method for sizing this rock is needed as it is not part of a blanket layer and must therefore withstand the ,
force of the flow by itself. The method must examine the incipient motion conditions, i.e., the velocity
and/or force required to begin to move the individual rock, either through sliding or rolling. If the rocks
are large enough, they can provide habitat benefits in the form of cover and refuge for anadromous fish ,
during high flows.
G8 Appendix C ~
' SUMMARY TABLES
The following four tables provide information on riprap specifications and gradations related to rock
diameters discussed in the design methods above. These tables will aid the designer in specifying riprap
~ gradations and also will assist in correlating the sizes in the design gradations to standard rock
specifications.
~
,
Toble C.1 Riprop sizes and corresponding weight.
,
Equivalent Weight'
, Diameter (inches) (pounds)
3 1
' . 6 11 9 36
12 86
15 170
' 18 290
21 460
24 690
~ 27 980
30 1350
33 1800
~ 36 2300
39 3000
42 3700
48 5500
' 54 7900
60 10800
, 1. Asavmes spherical roek at 165 pounds psr cubie foof.
~
~ Table C.2 Kin9 Counfy riprap speci$cafions by weight and 6ast dimension. (King County 1987.)
, Specification . Weight Range least Dimension
(pounds). (inches)
~ Two-man rock 300 ro 600 13
Three-man rock 800 to 1200 16
Four-man rock 1500 ro 2200 18
,
' qpPerd6c C G9
Table C.3 Washington Sia1c Depariment of TronsporFation riprap specifications relaied 1o D. ,
and D., diameters. (Adapfied from WSDOT 1991.)
Class Specification Interpreted Interpreted ~
D30 (inches) Dso (mches)
Quarry 100% must pass 8 in. sieve D30 < 3 Dso < 4 ,
Spalls 40% mox must pass 3 in. sieve
10% max must poss 0.75 in. sieve
light loose 20 to 90% should be between 300 3< D30 < 15 4< Dso < 22 I
Riprap Ibs. (2 cu. ft. to 0.5 cu. yd.)
.
80% should be between 50 Ibs. to 1 '
ton (0.33 cu. k. to 0.5 cu. R.)
Heovy loose 10 to 20% should have a maximum 15 < D30 < 18 22 < D50 < 30 ~
Riprap size oF 50 Ibs. (spolls)
40 to 90% should have a moximum ~
size of 1 ron (0.5 cu. yd.)
70 to 90% should have a minimum '
size oF 300 Ibs. (2 cu. R.)
10 to 30% should have a maximum ~
size of 50 Ibs. (spalls)
- ~
Table C.4. Comparison of riProP 9radaiions recommencled by vorious agencies.' ,
Relationship to D,o Diameror Relationship to D, Diameror ~
Diamater USACOE Riehardson USACOE Richardson Washington
(1991) et al. (1990) (1991) et al. (1990) Dept. of
Eeob9Y (1992) I
Do NS2 0.38 NS 0.25 0.25
D15 0.75 0.66 0.64 0.43 NS ~
p30 1.00 1.00 0.85 0.65 NS
pso 1.17 1.54 .1.00 1.00 1.00
Des 1.40 2.70 1.20 1.75 NS ~
D,oo 1.50 3.08 1.28 2.00 1.25 ro 1.5
1. The values for these gradatans hrne been adapted and interproted from the cited roferonees. ~
2. Not SpeeiFied.
,
C-IO Appendix t ,
r t
RECOMMENDED SOURCES FOR
' ADDITIONAL INFORMATION
~
Richardson, E.V., D.B. Simons, and P.Y. Julien.
1990. Highways in the River
~ Environment, Federal Highway
Administration.
' Maynord, S.T., J.F. Ruff, and S.R. Abt. 1989.
Riprap Design. Journai of Hydraulic
' Engineering. American Society of Civil
Engineers.
' King County Dept. of Public Works. 1990.
Surface Water Design Manual. Surface
Water Management Division. Seattle,
~ Wash.
U.S. Army Corps of Engineers. 1991.
, Hydraulie Design of F1ood Control
Channels, July 1, 1991. EM 1110-2-1601.
~ .
,
'
r i
i
1
1
' AwpendiX c c > >
~ r
~
~
. ~
~
~
~
~
~
~
~
~
~
. i
~
~
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~
APPEND/X D ~
EXAMPLE CONTRACT SPECIFICATIONS
1
The following information is an example of the written specifications that should be included with
~ construction drawings provided to a project contractor. These specifications will vary with contracts, projects, time of year, and site conditions.
~
PART 1: GENERAL
1
1.01 SCOPE OF WORK
~ Pmvide all materials and perform all work necessary and required to furnish and install all plantings
as indicated on the Drawings and specified herein, including initial maintenance of the same. The work
~ shall include, but not necessarily be limited to, the following:
A. Protection and maintenance of existing vegetation.
' B. Amendment, fertilizers, and soil preparation.
~ C. Tree stakes and braces.
D Planting of trees and shrubs, 1 gallon can size and larger.
' E. Planting of rooted stock; liners.
, F. Planting of live stakes.
G. Installation of fascines.
' H. Hydroseeding.
, J. Runoff diversion berms.
' K. Erosion control matting.
L. Inidal maintenance and watenng of all plantings.
'
'
,
APPendix D
' D-i
'
1.02 INSPECTIONS AND MAINTENANCE
A. Final insPection: '
Prior to the final inspection by Owner, the Contractor shall thoroughly clean all planting areas '
of excess soil, rubbish and debris, and clean paved and riprap areas.
The final inspection will be made upon request with five working days advance notice. '
B. Replanting and repairs: '
The Contractor shall monitor the site weekly for the first month after installation and within
48 hours after major storms that have -inch precipitation within any 24-hour period, ~
and report to the Owner any rilling, gullying, soil movement, failures, or plant dieback so
that prompt repair action can be taken.
~
C. Watering:
Water will be supplied on site by the . It is the Contractor's responsibility to provide a ~
pump truck, hoses or other equipment necessary for manual watering until the irrigation
system is in service. Use only clean, fresh water. ~
All installed plants including live stakes, fascines and rooted stock shall be thoroughly
watered within four hours of planting. ~
Initial watering shall gently and thomughly soak the new planring and flood the root zones
without washing soil particles down the slope. ~
Subsequent manual waterings shall be: 24 hours after planting of each plant, then every third
day. Quantity to be -inches of water over the site per watering. Duration: Watering to ,
continue until [Enter date]. [NOTE: this will vary to reflect site conditions and season. ]
Water shall be applied slowly enough to avoid runoff or soil movement. '
1.03 GENERAL ~
A. It is the intent of the design that no soil be imported or exported from the site.
w the extent of the work and the locations of erosion control work by designated ~
B. Drawmgs sho
areas: ~
Area A: Fascines, rooted stock, hydroseed.
Area B: Fascines, rooted stock, hydroseed. ,
Area C: Fascines, live stakes, rooted stock, hydroseed.
Area D: Runoff diversion berms, erosion control matting, live stakes, rooted stock, hydroseed.
Area E: Hydroseed. ~
Area F: Container planting, ground cover from tlats, amendments, mulch.
D~2 Appendix D ,
r ~
PART 2: PRODUCTS '
2.01 PIANT MATERIALS
' A. Live Non-rooted Cuttings for Fascines and Live stakes:
, Live cuttings shall be shoots from Salix (willow) species shrubs from the within a -mile
radius, and shall be free of disease. Use a minmum of two species grown in site condidons similar
' to the project site. Shoots shall be cut'cleanly as by shears or saw, not as by hatchet.' Cuttings
shall be brought to the site bundled and tagged with the day of harvest. The diameter shall be as
specified under "Live stakes" or "Fascines".
~ 1. Live stakes:
~ Shoots cut from live Salix species shrubs, cut from healthy wood. The shoots are to be
straight, - inch minimum length, -inch minimum diameter, -inch maximum
diameter, cut from the lower 213 of the branch, not the tip.
, Cuttings shall be cut cleanlY on a diagonal with a saw or pruning shears, not a hatchet. The
top of each cutting shall be 1 inch above aleaf bud, the bottom cut 1 inchbelow a leaf bud. Strip
' off all leaves and twigs.
2. Fascines:
~
Fascines bundles shall be prepared from live, shrubby material; Salix species. Up to
30 percent of the bundle may be non-rooting wood shrub material with prior approval of the
, County. Diameter shall be -inch to -inch maximum. Twigs and leaves are to
remain on the shoots. Cutting length shall be six to 10 feet.
' B. Rooted Stock, Liners:
' 1. The live transplants consisting of woody shrubs and tree shall be container grown. Quality
and size shall conform to the American Standard for Nursery Stock. Nursery-grown stock
only shall be used except where otherwise noted. Plant labels shall identify each species and
~ variety. Agricultural inspections of plant materials as required by City, County, or State shall
be the responsibility of the Contractor. Furnish certificates of inspection on request. The
Owner reserves the right to final inspection and rejection.
' 2. Containers shall have a minimum size of 9 cubic inches in volume and a depth of 8 inches.
It is preferable that container size shall not exceed a one-quart milk carton, one-gallon can
' size maximum.
3. Substitutions of plant variety or size shall be allowed only with specific approval which will
' be given only if the specified size or variety is unavailable.
4. The growing medium shall be any medium which will produce good quality plants. The
' plants specified usually grow best in a well-drained, well-aerated medium.
' Appendix D Q3
5. Root Systems: The growing medium shall be well filled with roots so that roots and medium i
form a cohesive unit when removed from the container. Roots shall be in good condition and
actively growing with white tips. ~
6. Top Growth: Top growth shall be commensurate with root growth, free from dead wood or
foliar diseases, and be a minimum of 5-inches high. Shrub species shall be pruned during '
production if necessary to stimulate branching and avoid "legginess", i.e. bare lower stems
and inability to stand upright.
C. Hydroseed Mix: ,
1. Seed: The hydroseed mix is to be the "non-irrigated mix" [List mix in terms of lbs./acre by '
species.] specified below:
All seed shall be delivered to the site tagged and labeled in accordance with the State ~
Agriculturai Code. Seed shall have a minimum pure live seed (PLS) content of 80 percent
(percent purity _ percent germination) and weed seed shall not exceed 0.5 percent of pure
live seed. ,
2. Virgin Wood Fiber: Fiber mulch shall be 2,000 lbs/acre. The fiber shall be cellulose fiber
that contains no germination or growth-inhibiting factors. It shall have the property of even ,
dispersion and suspension when agitated in water. It shall be colored with a nontoxic, water-
soluble green dye to provide a means of inetering for even distribution. ~
3. Tackifier: Tackifier shall consist of Plantago seed husks (Psyllium) such as Ecology Control,
M-Binder, Sentinel, or equal. When combined with fiber and water it shall have the property
of even dispersion and suspension. Tackifier rate shall be at lbs/acre [NOTE: varies '
according to site conditions].
4. Fertilizer for hydroseed mix: Fertilizer to be '
. [Sample: J 16• 16• 16 @ 2501bs/acre.
'
2.02 MATERIALS
A. Erosion Control Matting: . ~
Erosion control matting for Area D shall be ~
B. Fertilizer:
[Fertilizer needs will vary site by site. .Requires agricultural soil analysis tests, at a minimum ,
of two tests per acre and at changes of soil types and condition. The testing laboratory will
,
indicate quantities of necessary nutrients for ontirraum growth. ]
[A sample fertilizer specification: J
~
D-4 Appendix D ~
1 `
Fertilizer for rooted stock shall be a slow release, inorganic nitrogen source such as MagAmp
~ 7-40-7, coarse grade, or Osmocote, nine-month release, applied at the rate of 0.15 ounce of
nitrogen for tublings, or 0.30 ounce of nitrogen for one-gallon size containers; equalling 1
ounce of Osmocote per tubling or two ounces per one-gallon container. '
C. Straw:
, Straw shall be new, derived from cereal grains and free from mold and noxious weed seed. Straw
shall be furnished in air-dried bales. Straw shall be "long straw" having a minimum straw length
, of 15 inches. .
D. TopsoiL•
, No topsoil is to be added to areas A, B, C, or D. See Specifications for topsoil and tilling at Areas
E and F.
' E. Organic Soil Amendment
, If it is deternuned that site soils are low in organic content, sufficient amendment shall be added
to provide an optimum growth habitat, following recommendations of the agricultural tesdng
laboratory. The goal is to achieve 33 percent organic material in the top one foot of soil,
' minimum.
Organic soil amendment shall be 100 percent organic material that is porous and nitrogen
~ stabilized. Rotted or composted manures, vegetable matter, and sawdust are examples. The
Contractor shall submit 2, one-quart size, samples with attached cunent agricultural nutrient
, analysis to the Owner prior to installation.
' PART 3: EXECUTION
, 3.01 PLANTING
A. General requirements: ,
~ 1. All physical erosion control improvements, such as fencing of sensitive areas and existing
vegetation, water diversion berms and buried irrigation, shall be installed prior to planting.
~ 2. On Areas A, B and C plant rooted stock at 3 feet on center.
, 3. On Areas A, B and C plant live stakes on a 3 feet triangular spacing interspersed with live
rooted stock also at 3 feet apart, resulting in plants at 18 inches apart.
' 4. On Area D, plant live stakes on a 2 feet triangular spacing interspersed with live rooted stock
also at 2 feet apart, resulting in plants at 12 inches apart. Plant additional live stakes in two
rows, 6 inches apart both ways, directly adjacent to the channel edge.
~
~ ApPendix p D-5
i
5. Planting on Slopes: Planting on slopes shall proceed from the top to the bottom of the slope,
except that installation of fascines shall proceed from the bottom to the top. ~
B. Handling and storage of live cuttings:
~
Cuttings for live stakes and for fascines shall be planted the same day as cut. If not planted the
same day, cuttings shall not be stored longer than 24 hours. They shall be cut locally. During . ,
cutting, maintain orientation of the stems with all tops together. If stored overnight or more than
eight hours the lower half shall be kept submerged in fresh, clean water that is changed daily.
C. Live stakes: '
Live stakes shall be planted at 90 degrees to the slope, and buried a minimum of 20 inches, leaving ~
a minimum of two lateral leaf buds exposed. Ensure complete soil contact with the buried portion
of the cutting. Do not split or crack cuttings, or strip bark when planting. Plant cuttings right side
up. ~
D. Rooted stock:
1. Handling and Storage: Plants shall continue to receive regular irriSation when moved from ~
the nursery to the job site. All plants shall be watered immediately after planting so that
moisture around the rootball is at or near field capacity. Handling during planting shall be r
' such that overheating or excessive drying is avoided.
The Contractor shall adequately protect plants from damage due to sun, wind, or physical ~
abuse. Plants may be rejected at any time before or after planting if, in the opinion of the
County, they have suffered damage which affects either their appearance or health. '
Rooted stock shall be delivered to the job site a minimum of one week prior to planting if
temperatures at the nursery and the job site are significantly different. '
The Contractor shall reject all plants showing cracked or damaged rootballs, root binding, or
latent defects or disease. The Owner's inspector may further reject plants he or she considers '
unhealthy, badly formed, or inappropriate to the intent. All rejected plants shall immediately
be removed from the site.
2. Planting Pattern and Densities for Rooted stock: Plandngs of rooted stock shall be spaced '
in a triangular configurarion 36 inches apart or as otherwise indicated. Plants of different
species shall be mixed so as to be evenly distributed throughout the project. [NOTE: species ~
distribution will vary for each project. ]
All repair areas will have rooted stock throughout, except Areas E and F. ,
3. Planting Rooted stock: Actual planting shall follow the digging of holes as rapidly as possible
so that the excavated soil does not dry out. The planting shall take place no longer than two '
to three minutes following digging. Fertilizer shall be placed in bottom of pit and covered
with at least two inches of soil. Irrigated plants shall be set at the level they were grown in
the nursery and mulched to one inch to provide a soil cover over the root system. Non- '
D-6 APPendix D ~
irrigated plants shall have a 1.5-inch soil cover over the root system. Care shall be used to
use only the moist soil excavated forthe backfill. Backfill shall be tamped firmly to eliminate
all voids and to obtain intimate contact but not overcompacrion between the root systems and
the native soils. Excess soil shall be smoothed and firmed around the plants leaving a slight
depression to collect rainfall.
Rooted stock shall be removed carefully after containers have been cut on two sides with I' cutter. Do not lift or handle container plants by tops, stems, or trunks at any time.
I' Cut or remove containers only when ready to plant, complete planting of each plant promptly;
and water immediately after plantings. Plants shall not be out of their containers for more
than 30 minutes before being planted and watered.
Rooted stock shall be protected from deer and rodent browsing with wire mesh baskets,
• fencing or other pmtection. '
E. Fascines:
~ 1. B.undle Size: Fascine bundles may vary in length, depending on materials available. Bundles
sfiall taper at the ends and shall be 1 to 1-1/2 feet longer than the average length of stems,
to achieve this taper. When compressed firmly and tied, each bundle shall be 8 inches in
' dianeter.
2. Bundle Construction: Stems shall be placed altemately (randomly) in each bundle so that
t approximately one-half the live butt ends are at each end of the bundle.
, 3. Bundle Tying: Bundles shall be tied on not more than.15-inch centers with a minimum of
two wraps •of binder twine or heavier tying materials with a non-slipping knot. Tying may
be done with strapping machines as long as the bundles are compressed tighdy.
~ 4. Timing of Preparation: Bundles shall be prepared not more than one day in advance of
placement. They shall be kept covered, in fresh water and in the shade for up to 8 hours. See
' 3.013 "Handling and Storage."
5. Grade: Grade for fascines trenches shall be staked with an Abney level or similar device, and
' shall follow slope contours (i.e. they shall be horizontal and level).
6. Spacing: [Sample: ] Fascines shall be spaced at 5-ft. vertical spacing. [Varies according to
~ slope conditions. ]
7. Installation: Bundles shall be laid in trenches dug to approacimately two-thirds of the diameter
t of the bundles. Bundles shall be placed with ends overlapping at least 12 inches. The overlap
must be sufficient to allow the last tie on each bundle to overlap.
~ 8. Staking: Bundles shall be staked firmly in place with vertical stakes on the downhill side of
the fascines not more than 24 inches on centerand with stakes through the bundles at not more
than 36 inches on center. When bundles overlap between two previously set guide or bottom
' stakes, an additional bottom stake shall be used at the midpoint of the overlap. The overlap
' Appendix p D-7
shall be secured with a stake through the ends of both bundles and inside the end tie of each ~
bundle.
9. Stake Materials: Stakes to be construction stakes 2 in. x 4 in. x 36 in., cut diagonally. '
10. Backfilling: Fascines shall be covered immediately and tamped. Ensure that there is
complete soil contact with buried portions. Workers are encouraged to walk on the fascines '
as work progresses to further work the soil into the bundles. Ten to twenty percent of the
top of each bundle shall be left exposed when all construction is completed.
11. Staking: All stakes shall be driven to a firm hold and a minimum of 18-inches deep. ~
12. Progression of Work: Work shall progress from the bottom of the slope to the top and each '
row shall be covered with soil, leaving 2 inches exposed, and the soil shall be packed firmly
behind and into the bundle by tamping or walking on the bundles or by both these methods.
sure of the fascines to sun and wind shall be minimized ,
13. Prevention of Drymg Damage: Expo
throughout the operation. Trenches shall be dug only as rapidly as the fascines is being placed
and covered to minimize drying of the soil in the trench and of the backfill. ~
F. Hydroseeding: '
1. Seed shall be broadcast by hydroseeding. Care shall be exercised to avoid damaging the
transplants and cuttings. ~
2. Time of Seeding: Grading, gully or rill repairs, biotechnical construction and planting of
transplants and live stakes shall be completed before seeding. Graded slopes shall be left in '
a roughened condition.
G. Mulch Application: ~
[Sample: J Areas A and B shall be mulched with straw within two working days following
seeding unless prevented by weather and approved by the Project Designer. Straw shall be ~
uniformly distributed at the rate of not less than two nor more than three tons per acre in Areas
A and B only; no straw shall be placed over geogrid Area D.
Straw may be applied in two ways, either as whole straw applied by hand or with a straw blower. ~
Whole Straw Application-Spreading shall be by hand. Straw shall be crimped into the ground '
using digging or tile spades to avoid damaging transplants. Straw Blower Application-
Application by blower will only be done when wind velocities are low enough.to prevent blowing
of the straw off the slope. ~
H. Erosion Control Matting: ~
See manufacturer's overlap and stapling specifications.
~
D-8 APpendix D '
' ` .
~
DISTRIBUTION ~
' To obtain copies of this document, Guidelines For Bank Stabilization Projects in the Riverine fnvironments of King
Counly, contact King Couny Department oF Public Works, SurFace Waier Management Division at (206) 296-6519.
~
,
~
,
'
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APPENDIX C:
GREEN RIVER PUMP OPERATIONS PROCEDURES PLAN
Bound separately from this agreement.
July 2002 Page 15 of 17
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Green River BaVi~ Progium
Serving Auburn, Kent, Renton, Tuk-Nc-rila and King County
PUMP OPERATIONS PROCEDURES;PLAN
APPENDICES
TABLE OF CONTENTS
I. Appendices
A. Green River Profiles and Elevations
B. Stage - Discharge Tabulations
C. Surface Water Management Facilities Inventory Forms
D. Interim Typical Cross Section
05/13186
Appendix A
Green River Profiles and Elevations
(Under separate cover; up-to-dete folios are maintained by the Cities of Auburn,
Kent, Renton, and Tukwila, and by King County) <
03/06/86
Appendix B
Stage - Discharge Tabulations
. ~
I J
03/06/86
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Appendix C
Surface Water Management Facilities Inventory Forms _
c
C3/06/86
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APPENDIX D:
SUPPLEMENTAL WORK PROGRAM
PUMP STATIONS: In association with the operation and maintenance of the pump stations,
King County is to:
1. Develop a scope of work to reevaluate and, if appropriate, develop an update to the Pump
Operations Procedures Plan that is consistent with contemporary standards and operating
requirements. This evaluation may include, as appropriate, the following:
➢ Hydraulic analyses evaluating current conditions in order to provide the technical basis
for the monitoring and operation of the pump stations as they interrelate to interior runoff
and flow discharge of the Green River.
➢ A pump rating analysis of the Black River (P-1), Tukwila (P-17) and Segale pump
stations.
➢ The development of a spill response plan for the Black River pump station that identifies
and addresses the specific operating procedures of the pump station in the event that a
hazardous substance enters into the Springbrook Creek sub-basin drainage.
➢ Study the feasibility of improving upstream and downstream fish passage at the Black
River pump station.
2. Seek federal and state disaster mitigation grant funds to complete seismic upgrades to
above-ground diesel fuel tanks of the Black River pump station in order to ensure
compliance with Washington State codes and standards.
3. Develop an amortization schedule for the Green River pump stations' facilities and
equipment, and develop a repair and replacement plan consistent with the fund balance of
the Green River Flood Control Zone District that is designated for those purposes.
POST-FLOOD RECOVERY PLAN: The Post-Flood Recovery Plan for the Lower Green River
Basin (1994) shall be updated following any significant alteration in the lower Green River
basin's physical environment that would affect how the Plan may be implemented.
STUDIES: The following studies, in addition to any others determined to be necessary towards
achieving the goals and objectives of the Green River Flood Control Zone District, will be
coordinated and reviewed by the Technical and Executive Committees for the purposes of
providing recommendations for consideration by the Board of Supervisors:
July 2002 Page 16 of 17
1. Financing Alternatives Analysis. In accordance with the direction given by the Executive
Committee at its annual meeting in October 2001, King County will further evaluate the
bond financing mechanisms available to the Green River Flood Control Zone District for
its major maintenance and operations projects, and provide to the Executive Committee
a detailed financial and expenditure plan that addresses the need for additional revenue
based upon issuance of a King County financed bond.
2. Risk-Based Flood Damage Analysis. King County will further pursue risk-based flood
damage analysis for the Green River Flood Control Zone District in order to more
accurately determine potential flood-related damages and the expected average annual
avoided damages. The results of the analysis are intended to provide King County and
other municipalities with an baseline foundation for developing a prioritized long-term
levee and revetment repair, reconstruction and maintenance plan, and to provide the
basis for securing additional revenue sources to accomplish the necessary maintenance
and repair projects.
MILL CREEK: King County, the Cities of Auburn and Kent, and other interested parties will
jointly work to finalize the Mill Creek/Mullen Slough Basin Action Plan. The Plan
recommendations will include a set of projects and policies designed to: minimize chronic
flooding; improve drainage and conveyance conditions; improve agricultural waterways; and
enhance riparian/salmonid habitat. King County and the Cities of Auburn and Kent will reinitiate
the Mill Creek Flood Management Plan Interlocal Agreement to implement the projects and
policies contained as recommendations within the Mill Creek/Mullen Slough Basin Action Plan.
I July 2002 Page 17 of 17