HomeMy WebLinkAbout20090923000631 STORM WATER EASEMENT AND MAINTENANCE AGREEMENT 091809Return Address:
City of Auburn
City Clerk
25 West Main
Auburn, WA 98001
EXCISE TAX NOT REQUIRED
KhV Co. Re cards Divisloft,
Above this line reserved for recording information.
STORM WATER EASEMENT AND MAINTENANCE AGREEMENT
KCP09-0001 PAGI tG NOR HWEST TITLE
Reference # (if applicable): N/A
0
Z45 -1-2-
Grantor/Borrower: Auburn School District No. 408
Grantee/Assignee/Beneficiary: City of Auburn q
Legal Description/STR: NE S 4, T21 N, R5E f I
Assessor's Tax Parcel ID#: 0421059070 & 0421059085 '7
THIS EASEMENT AND AGREEMENT made and entered into this 1-14-$' day of
agole,, hw , 2009, by and between the City of Auburn, a municipal corporation
of king County, Washington, hereinafter referred to as "CITY" and
Auburn School District hereinafter referred to as "PROPERTY OWNER".
WHEREAS, PROPERTY OWNER has applied for certain permits with the CITY
for the construction of facilities for Auburn Mountainview High School located at
28900124 Ih Avenue SE, which create impervious surface; and
WHEREAS, the PROPERTY OWNER will complete a storm system; and
WHEREAS, the PROPERTY OWNER and the CITY desire that the storm system
be maintained to provide adequate facilities for controlling both the quantity and quality of
storm drainage; and
WHEREAS, for maintenance of a storm system it is necessary to have appropriate
right-of-way to bring in equipment to conduct maintenance functions; and
WHEREAS, maintenance requirement is a covenant running with the land and
binding upon all heirs, successors and assigns of both parties; and
WHEREAS, the parties desire that this Agreement be recorded to advise heirs,
successors and assigns of both parties as to the existence of this easement and agreement;
and
Storm Water Easement and Maintenance Agreement
Page I of 20
WHEREAS, an easement is needed to bring in maintenance equipment; and
WHEREAS, the parties are both desirous of permitting inspection of the storm
system to make certain that it is functioning properly and for purposes of determining the
appropriate repairs.
NOW, THEREFORE, BASED UPON MUTUAL COVENANTS TO BE
DERIVED THE PARTIES AGREE AS FOLLOWS:
Section 1, EASEMENT
PROPERTY OWNER hereby provides a non-exclusive easement to the City for
access, inspection, and maintenance for the purposes of this Agreement and the attached
Storm Water Pollution Prevention Plan, over, under and on that real estate described in
Exhibit "A" & "B" and on that portion of the property as showing on the approved Record
Drawings revised pursuant to construction records for the City of Auburn, which record
drawings are hereby incorporated by reference as if set out in full. This easement shall be a
burden to that real estate which is legally described and attached as Exhibit "A" & "B" and
incorporated herein by this reference, and shall be a benefit to the City Storm Drainage
Utility System.
Section 2, HEIRS, SUCCESSORS AND ASSIGNS
This Agreement shall be binding upon the heirs, successors and assigns of the
parties.
Section 3, MAINTENANCE
The PROPERTY OWNER agrees to maintain the storm system in accordance with
the ordinances and all applicable codes of the CITY and the Storm Water Pollution
Prevention Maintenance and Operation Schedule attached as Exhibit "C" and incorporated
herein by this reference. The PROPERTY OWNER does hereby agree that the CITY may
enter onto the property of the PROPERTY OWNER via the easement described above to
inspect and perform necessary maintenance if, after the PROPERTY OWNER is given
notice to maintain, the PROPERTY OWNER fails to maintain. Further, the PROPERTY
OWNER agrees the CITY may enter onto the property of PROPERTY OWNER via the
easement described above to perform emergency maintenance in the event of the storm
system's failure which might result in adverse impacts(s) on public facilities or private
facilities of other property owners. In both events the PROPERTY OWNER agrees to
reimburse the CITY for the costs incurred by the CITY in maintaining the storm system.
Should the CITY incur attorney's fees and/or costs in enforcing the agreement and/or in
maintaining or collecting maintenance fees, the PROPERTY OWNER agrees to pay
reasonable attorney's fees and all costs incurred by the CITY.
Storm Water Easement and Maintenance Agreement
Page 2 of 20
Section 4, ACKNOWLEDGMENT OF OTHER ENFORCEMENT ACTIONS
PROPERTY OWNER acknowledges that there may be liability for violations of
codes that could result in additional fines and/or the possibility of incarceration in addition
to the fees for maintenance should violations occur.
EXECUTED as of the date first written above.
CITY OF AUBURN
tm Carlaw, Storm Drainage Engi r' Date
STATE OF WASHINGTON)
)ss.
COUNTY OF KING )
I certify that I know or have satisfactory evidence that Tim Carlaw is the person who
appeared before me, and said person acknowledged that he signed this instrument, on oath
stated that he was authorized to execute the instrument and acknowledged it as the
STORM DRAINAGE ENGINEER of THE CITY OF AUBURN to be the free and
voluntary act of such party for the uses and purposes mentioned in this instrument.
Dated
h4 it+CT~A`y y .C
N q4~`~4 a' Z
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l~OR WASN\;
Residing at I ~ C C
My appointment expires [ /
Storm Water Easement and Maintenance Agreement
Page 3 of 20
AUBURN SCHOOL DISTRICT NO. 408,
a municipal corporation of the State of Washington
I-1- arj
D. K. Herren Date
Superintendent
STATE OF WASHINGTON)
) ss
COUNTY OF KING )
I certify that I know or have satisfactory evidence that JZwt I(/5 9V KJ flerre h
is the person who appeared before me, and said person acknowled ed that they signed this
instrument, on oath stated that they were authorized to execute the instrument and
acknowledged it as the Superintendent of the Auburn School District No. 408,
a municipal corporation, to be the free and voluntary act of such party for the uses and
purposes mentioned in this instrument.
Dated 91/9/4
xy Notary Public in and fo the State of Washington
Residing at yy~p~7(~ IJ
My appointment expires 3- l9 -.2011
a
KT/tlb
Storm Water Easement and Maintenance Agreement
Page 4 of 20
EXHIBIT `A'
Auburn Mountainview High School
Legal Description of Property
THAT PORTION OF GOVERNMENT LOT 1 IN THE NORTHEAST QUARTER OF THE
NORTHEAST QUARTER AND THAT PORTION OF GOVERNMENT LOT 2 IN THE NORTHWEST
QUARTER OF THE NORTHEAST QUARTER ALL LYING WITHIN SECTION 4, TOWNSHIP 21
NORTH, RANGE 5 EAST OF THE WILLAMETTE MERIDIAN IN KING COUNTY,
WASHINGTON, BEING KNOWN AS CONSOLIDATED LOT IN BOUNDARY LINE
ADJUSTMENT NO. LOOL0065 AS RECORDED UNDER RECORDING NO. 20001212900014,
RECORDS OF KING COUNTY, WASHINGTON.
EXCEPT THOSE PORTIONS CONVEYED TO KING COUNTY FOR ROAD PURPOSES IN QUIT
CLAIM DEED RECORDED UNDER RECORDING NO. 20030509000004, RECORDS OF KING
COUNTY, WASHINGTON.
Storm Water Easement and Maintenance Agreement
Page 5 of 20
EXHIBITS'
Storm Water Easement and Maintenance Agreement
Page 6 of 20
MATCH LINE W
Storm Water Easement and Maintenance Agreement
Page 7 of 20
EXHIBIT `C'
STORMWATER POLLUTION PREVENTION
MAINTENANCE and OPERATION SCHEDULE
for
Auburn Mountainview High School
Site Address:
The project is located in NE of Section 4, Township 21 North, Range 5
East, W.M., 28900 124th Avenue SE. The tax parcel numbers are
0421059070 and 0421059085.
Introduction:
This report has been prepared to address the City of Auburn's storm
drainage and pollution prevention requirements for the Auburn
Mountainview High School located at 28900 124th Avenue SE. The site
has an area of approximately 40 acres and was utilized as farmland with
some residential, prior to the construction of the high school.
The subject site includes a new 1,500 student High School with
approximately 193,000 square feet in a one-story structure. The developed
site includes paved pedestrian areas, parking lots, a bus drop off area, four
ball fields, a soccer/football track and field, and eight tennis courts.
According to the City of Auburn's Construction Standards for stormwater
management, the City requires stormwater quantity and quality control to all
proposed developments. The site is designed to collect all of the
stormwater runoff from the landscaped, building, and pavement areas in a
series of catch basins. This water is conveyed by storm drainage pipe to
two stormwater detention ponds located at the west and east portions of
the site. From the east detention pond, the stormwater is released into a
bioswale along the south side of the detention pond before entering into a
24-inch storm drainage line running to the north through the east bank of
the pond. This line then travels to the east along the north access drive to
132nd Avenue SE and discharges into the west ditch along 132nd Avenue
SE at the northeast corner of the site. From the west detention pond,
stormwater is released into a bioswale along the west side of the detention
Storm Water Easement and Maintenance Agreement
Page 8 of 20
pond before entering into an 18-inch storm drainage line running to the
south and discharging to the east ditch along 124`h Avenue SE.
Plan Goal:
The specific purpose for the stormwater facility is to minimize pollution that
is typically associated with modern development; in general, pollution from
motor vehicles and pollution generated from erosion. Attached to this
narrative is a maintenance manual that offers guidelines to the owner for
stormwater facility maintenance.
Prevention BMPs:
The catch basins shall have stenciled on them "DUMP NO WASTE -
DRAINS TO STREAM." The owner shall be responsible for sweeping the
lot, installing storm drainage stenciling, and providing spill control
procedures. In case of spill, call the Department of Ecology at 1-425-649-
7000. The catch basins, detention/wetpond, and control structures will be
visually inspected for accumulation of debris and silt and will be maintained
as required by this Stormwater Pollution Prevention Plan and attachments.
Maintenance Standards for Drainage Facilities (from the Department
of Ecology Stormwater Manual, August 2001)
No. 1 - Detention Pond
No. 4 - Control Structure/Flow Restrictor
No. 5 - Catch Basins
No. 7 - Energy Dissipaters
No. 8 - Typical Biofiltration Swale
Treatment BMPs:
Two post detention wet bioswales and one pre wetland bioswale have been
installed to treat runoff for conventional pollutants. The bioswales after
detention were designed to treat the 2-year release rate from the pond for
water quality treatment. The bioswale prior to the wetland was designed to
treat 60% of the developed 2-year peak storm event (water quality storm)
for water quality treatment. In addition, the detention ponds were designed
to detain the volume created from releasing half the existing 2-year through
50-year peak durations.
Storm Water Easement and Maintenance Agreement
Page 9 of 20
The City of Auburn Storm Drainage Utility section is to review and approve
any changes to this Stormwater Pollution Prevention Plan prior to changes
in its implementation. Additionally, any changes in ownership or person of
responsibility are to be reported to the City of Auburn Storm Drainage Utility
section.
Inspection/Maintenance:
Regular inspections of the drainage facilities should be carried out twice per
year, in the spring and fall. The responsible party should keep records of
these inspections available for review by the City. Additional inspections
may be required after severe storms.
Routine maintenance of the site will include mowing, care of landscaping,
and the removal of trash and debris from the drainage system. The parking
lots and driveways should be kept clean and in repair. Events such as
major storms or heavy winds will require immediate inspections for
damages.
To ensure proper water quality and treatment, the post-detention bioswales
and the pre-discharge to the wetlands bioswale must be properly
maintained. Be careful to avoid introducing landscape fertilizer to receiving
waters or groundwater.
Catch basins shall be cleaned when sump is one-third of one foot full of
sediment or debris.
Person of Responsibility:
Mr. Jeffrey L. Grose
Executive Director of Capital Projects
Auburn School District
915 Fourth Street NE
Auburn, WA 98002
(253) 931-4826
Design Engineer:
David Rhoades, P.E.
RoseWater Engineering, Inc.
1201 Third Avenue, Suite 1500
Seattle, WA 98101
(206) 441-9385
Stone Water Easement and Maintenance Agreement
Page 10 of 20
Plan and/or Information Updates:
The City of Auburn Storm Drainage Utility section is to review and approve
any changes to this Stormwater Pollution Prevention Plan prior to changes
in its implementation. Additionally, any changes in ownership or person of
responsibility are to be reported to the City Storm Drainage Utility section.
INSPECTION/MAINTENANCE CHECKLIST
STRUCTURE
Results/
Maintenance
Date
Detention Ponds
Inspection
Results
Maintenance
Done
Flow Control
Inspection
Structures
Results
Maintenance
Done
Catch Basins
Inspection
Results
Maintenance
Done
Energy Dissipaters
Inspection
Results
Maintenance
Done
Bioswales
Inspection
Results
Maintenance
Done
Storm Water Easement and Maintenance Agreement
Page 11 of 20
Maintenance Standards for Drainage Facilities:
The facility-specific maintenance standards contained in this section are
intended to be conditions for determining if maintenance actions are
required, as identified through inspection. They are not intended to be
measures of the facility's required condition at all times between
inspections. In other words, exceeding these conditions at any time
between inspections and/or maintenance does not automatically constitute
a violation of these standards. However, based upon inspection
observations, the inspection and maintenance schedules shall be adjusted
to minimize the length of time that a facility is in a condition that requires a
maintenance action.
No.1- Detention Ponds
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General
Trash & Debris
Any trash and debris which exceed
Trash and debris cleared from site.
5 cubic feet per 1,000 square feet
(this is about equal to the amount of
trash it would take to fill up one
standard size garbage can). In
general, there should be no visual
evidence of dumping.
If less than threshold all trash and
debris will be removed as part of next
scheduled maintenance.
Poisonous
Any poisonous or nuisance
No danger of poisonous vegetation
Vegetation and
vegetation which may constitute a
where maintenance personnel or the
noxious weeds
hazard to maintenance personnel or
public might normally be. (Coordinate
the public.
with local health department.)
Any evidence of noxious weeds as
Complete eradication of noxious weeds
defined by State or local regulations.
may not be possible. Compliance with
State or local eradication policies
(Apply requirements of adopted IPM
required.
policies for the use of herbicides).
Contaminants
Any evidence of oil, gasoline,
No contaminants or pollutants present.
and Pollution
contaminants, or other pollutants.
(Coordinate removal/cleanup with
local water quality response agency).
Rodent Holes
Any evidence of rodent holes if
Rodents destroyed and dam or berm
facility is acting as a dam or berm, or
repaired. (Coordinate with local health
any evidence of water piping through
department; coordinate with Ecology
dam or berm via rodent holes.
Dam Safety Office if pond exceeds 10
acre-feet.)
Storm Water Easement and Maintenance Agreement
Page 12 of 20
No.1- Detention Ponds
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Beaver Dams
Dam results in change or function of
Facility is returned to design function.
the facility.
(Coordinate trapping of beavers and
removal of dams with appropriate
permitting agencies.)
Insects
When insects such as wasps and
Insects destroyed or removed from
hornets interfere with maintenance
site.
activities.
Apply insecticides in compliance with
adopted IPM policies.
Tree Growth
Tree growth does not allow
Trees do not hinder maintenance
and Hazard
maintenance access or interferes
activities. Harvested trees should be
Trees
with maintenance activity (i.e., slope
recycled into mulch or other beneficial
mowing, silt removal, vactoring, or
uses (e.g., alders for firewood).
equipment movements). If trees are
not interfering with access or
Remove hazard trees.
maintenance, do not remove.
If dead, diseased, or dying trees are
identified.
(Use a certified Arborist to determine
health of tree or removal
requirements.)
Side Slopes
Erosion
Eroded damage over 2 inches deep
Slopes should be stabilized using
of Pond
where cause of damage is still
appropriate erosion control measure(s);
present or where there is potential for
e.g., rock reinforcement, planting of
continued erosion.
grass, compaction.
Any erosion observed on a
If erosion is occurring on compacted
compacted berm embankment.
berms, a licensed civil engineer should
be consulted to resolve source of
erosion.
Storage Area
Sediment
Accumulated sediment that exceeds
Sediment cleaned out to designed
10% of the designed pond depth
pond shape and depth; pond reseeded
unless otherwise specified or affects
if necessary to control erosion.
inletting or outletting condition of the
facility.
Liner (If
Liner is visible and has more than
Liner repaired or replaced. Liner is
Applicable)
three 1/4-inch holes in it.
fully covered.
Storm Water Easement and Maintenance Agreement
Page 13 of 20
No.1- Detention Ponds
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Pond Berms
Settlements
Any part of berm that has settled 4
Dike is built back to the design
(Dikes)
inches lower than the design
elevation.
elevation.
If settlement is apparent, measure
berm to determine amount of
settlement.
Settling can be an indication of more
severe problems with the berm or
outlet works. A licensed civil
engineer should be consulted to
determine the source of the
settlement.
Piping
Discernable water flow through pond
Piping eliminated. Erosion potential
berm. Ongoing erosion with potential
resolved.
for erosion to continue.
(Recommend a Goethechnical
engineer be called in to inspect and
evaluate condition and recommend
repair of condition.
Emergency
Tree Growth
Tree growth on emergency spillways
Trees should be removed. If root
Overflow/
creates blockage problems and may
system is small (base less than 4
Spillway and
cause failure of the berm due to
inches), the root system may be left in
Berms over
uncontrolled overtopping.
place. Otherwise, the roots should be
4 feet in
removed and the berm restored. A
height.
Tree growth on berms over 4 feet in
licensed civil engineer should be
height may lead to piping through the
consulted for proper berm/spillway
berm which could lead to failure of
restoration.
the berm.
Piping
Discernable water flow through pond
Piping eliminated. Erosion potential
berm. Ongoing erosion with
resolved.
potential for erosion to continue.
(Recommend a Goethechnical
engineer be called in to inspect and
evaluate condition and recommend
repair of condition.
Emergency
Emergency
Only one layer of rock exists above
Rocks and pad depth are restored to
Overflow/
Overflow/
native soil in area five square feet or
design standards.
Spillway
Spillway
larger, or any exposure of native soil
at the top of out flow path of spillway.
(Riprap on inside slopes need not be
replaced.)
Erosion
See "Side Slopes of Pond:"
Storm Water Easement and Maintenance Agreement
Page 14 of 20
No. 4 - Control Structure/Flow Restrictor
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General
Trash and
Material exceeds 25% of sump depth
Control structure orifice is not blocked.
Debris (Includes
or 1 foot below orifice plate.
All trash and debris removed.
Sediment)
Structural
Structure is not securely attached to
Structure securely attached to wall and
Damage
manhole wall.
outlet pipe.
Structure is not in upright position
Structure in correct position.
(allow up to 10% from plumb).
Connections to outlet pipe are not
Connections to outlet pipe are
watertight and show signs of rust.
watertight; structure repaired or
replaced and works as designed.
Any holes, other than designed
Structure has no holes other than
holes, in the structure.
designed holes.
Cleanout
Damaged or
Cleanout gate is not watertight or is
Gate is watertight and works as
Gate
Missing
missing.
designed.
One maintenance person cannot
Gate moves up and down easily and is
move up and down gate.
watertight.
Chain/rod leading to gate is missing
Chain is in place and works as
or damaged.
designed.
Gate is rusted over 50% Of its surface
Gate is repaired or replaced to meet
area.
design standards.
Orifice Plate
Damaged or
Control device is not working properly
Plate is in place and works as
Missing
due to missing, out of place, or bent
designed.
orifice plate.
Obstructions
Any trash, debris, sediment, or
Plate is free of all obstructions and
vegetation blocking the plate.
works as designed.
Overflow Pipe
Obstructions
Any trash or debris blocking (or
Pipe is free of all obstructions and
having the potential of blocking) the
works as designed.
overflow pipe.
Manhole
See "Closed
See "Closed Detention Systems"
See "Closed Detention Systems"
Detention
(No. 3).
(No. 3).
Systems"
(No. 3).
Catch Basin
See "Catch
See "Catch Basins" (No. 5).
See "Catch Basins" (No. 5).
Basins"
(No. 5).
Storm Water Easement and Maintenance Agreement
Page 15 of 20
No. 5 - Catch Basins
General
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Trash & Debris
Trash or debris which is located
No Trash or debris located immediately
immediately in front of the catch
in front of catch basin or on grate
basin opening or is blocking inletting
opening.
capacity of the basin by more than
10%.
Trash or debris (in the basin) that
No trash or debris in the catch basin.
exceeds 60 percent of the sump
depth as measured from the bottom
of basin to invert of the lowest pipe
into or out of the basin, but in no
case less than a minimum of six
inches clearance from the debris
surface to the invert of the lowest
pipe.
Trash or debris in any inlet or outlet
Inlet and outlet pipes free of trash or
pipe blocking more than 1/3 of its
debris.
height.
Dead animals or vegetation that
No dead animals or vegetation present
could generate odors that could
within the catch basin.
cause complaints or dangerous
gases (e.g., methane).
Sediment
Sediment (in the basin) that exceeds
No sediment in the catch basin.
60 percent of the sump depth as
measured from the bottom of basin to
invert of the lowest pipe into or out of
the basin, but in no case less than a
minimum of 6 inches clearance from
the sediment surface to the invert of
the lowest pipe.
Structure
Top slab has holes larger than 2
Top slab is free of holes and cracks.
Damage to
square inches or cracks wider than
Frame and/or
1/4 inch.
Top Slab
(Intent is to make sure no material is
running into basin).
Frame not sitting flush on top slab,
Frame is sitting flush on the riser rings
i.e., separations of more than 314
or top slab and firmly attached.
inch of the frame from the top slab.
Frame not securely attached
Fractures or
Maintenance person judges that
Basin replaced or repaired to design
Cracks in Basin
structure is unsound.
standards.
Walls/ Bottom
Grout fillet has separated or cracked
Pipe is regrouted and secure at basin
wider than 1/2 inch and longer than 1
wall.
foot at the joint of any inlet/outlet pipe
or any evidence of soil particles
entering catch basin through cracks.
Storm Water Easement and Maintenance Agreement
Page 16 of 20
No. 5 - Catch Basins
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If failure of basin has created a
Basin replaced or repaired to design
Misalignment
safety, function, or design problem.
standards.
Vegetation
Vegetation growing across and
No vegetation blocking opening to
blocking more than 10% of the basin
basin.
opening.
Vegetation growing in inlet/outlet pipe
No vegetation or root growth present.
joints that is more than six inches tall
and less than six inches apart.
Contamination
See "Detention Ponds" (No. 1).
No pollution present.
and Pollution
Catch Basin
Cover Not in
Cover is missing or only partially in
Catch basin cover is closed.
Cover
Place
place. Any open catch basin requires
maintenance.
Locking
Mechanism cannot be opened by one
Mechanism opens with proper tools.
Mechanism Not
maintenance person with proper
Working
tools. Bolts into frame have less than
1/2 inch of thread.
Cover Difficult
One maintenance person cannot
One maintenance person can remove
to Remove
remove lid after applying normal
cover.
lifting pressure.
(Intent is keep cover from sealing off
access to maintenance.)
Ladder
Ladder Rungs
Ladder is unsafe due to missing
Ladder meets design standards and
Unsafe
rungs, not securely attached to basin
allows maintenance person safe
wall, misalignment, rust, cracks, or
access.
sharp edges.
Metal Grates
Grate opening
Grate with opening wider than 7/8
Grate opening meets design standards.
(If Applicable)
Unsafe
inch.
Trash and
Trash and debris that is blocking
Grate free of trash and debris.
Debris
more than 20% of grate surface
inletting capacity.
Damaged or
Grate missing or broken member(s)
Grate is in place and meets design
Missing
of the grate.
standards.
Storm Water Easement and Maintenance Agreement
Page 17 of 20
No. 7 - Energy Dissipaters
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External:
Rock Pad
Missing or
Only one layer of rock exists above
Rock pad replaced to design standards.
Moved Rock
native soil in area five square feet or
larger, or any exposure of native soil.
Erosion
Soil erosion in or adjacent to rock
Rock pad replaced to design standards.
pad.
Dispersion
Pipe Plugged
Accumulated sediment that exceeds
Pipe cleaned/flushed so that it matches
Trench
with Sediment
20% of the design depth.
design.
Not Discharging
Visual evidence of water discharging
Trench redesigned or rebuilt to
Water Properly
at concentrated points along trench
standards.
(normal condition is a "sheet flow" of
water along trench). Intent is to
prevent erosion damage.
Perforations
Over 1/2 of perforations in pipe are
Perforated pipe cleaned or replaced.
Plugged.
plugged with debris and sediment.
Water Flows
Maintenance person observes or
Facility rebuilt or redesigned to
Out Top of
receives credible report of water
standards.
"Distributor'
flowing out during any storm less
Catch Basin
than the design storm or it's causing
or appears likely to cause damage.
Receiving Area
Water in receiving area is causing or
No danger of landslides.
Over-Saturated
has potential of causing landslide
problems.
Internal:
Manhole/
Worn or
Structure dissipating flow deteriorates
Structure replaced to design standards.
Chamber
Damaged Post,
to 1/2 of original size or any
Baffles, Side of
concentrated worn spot exceeding
Chamber
one square foot that would make
structure unsound.
Other Defects
See "Catch Basins" (No. 5).
See "Catch Basins" (No. 5).
Storm Water Easement and Maintenance Agreement
Page 18 of 20
No. 8 - Typical Biofiltration Swale
General
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Sediment
Sediment depth exceeds 2 inches.
Remove sediment deposits on grass
Accumulation
treatment area of the bio-Swale. When
on Grass
finished, swale should be level from
side to side and drain freely toward
outlet. There should be no areas of
standing water once inflow has ceased.
Standing Water
When water stands in the swale
Any of the following may apply: remove
between storms and does not drain
sediment or trash blockages, improve
freely.
grade from head to foot of swale,
remove clogged check dams, add
underdrains or convert to a wet
biofiltration swale.
Flow Spreader
Flow spreaders uneven or clogged so
Level the spreader and clean so that
that flows are not uniformly
flows are spread evenly over entire
distributed through entire swale
swale width.
width.
Constant
When small quantities of water
Add a low-flow pea-gravel drain the
Baseflow
continually flow through the swale,
length of the swale or by-pass the base
even when it has been dry for weeks,
flow around the swale.
and an eroded, muddy channel has
formed in the swale bottom.
Poor Vegetation
When grass is sparse or bare, or
Determine why grass growth is poor
Coverage
eroded patches occur in more than
and correct that condition. Re-plant
10% of the swale bottom.
with plugs of grass from the upper
slope: plant in the swale bottom at
8-inch intervals. Or re-seed into
loosened, fertile soil.
Vegetation
When the grass becomes
Mow vegetation or remove nuisance
excessively tall (greater than 10-
vegetation so that flow not impeded.
inches); when nuisance weeds and
Grass should be mowed to a height of
other vegetation start to take over.
3 to 4 inches. Remove grass clippings.
Excessive
Grass growth is poor because
If possible, trim back over-hanging
Shading
sunlight does not reach swale.
limbs and remove brushy vegetation on
adjacent slopes.
Inlet/Outlet
Inlettoutlet areas clogged with
Remove material so that there is no
sediment and/or debris.
clogging or blockage in the inlet and
outlet area.
Trash and
Trash and debris accumulated in the
Remove trash and debris from
Debris
bio-swale.
bioswale.
Accumulation
Storm Water Easement and Maintenance Agreement
Page 19 of 20
Storm Water Easement and Maintenance Agreement
Page 20 of 20
No. 8 -Typical Biofiltration Swale