HomeMy WebLinkAbout30th Street Flooding Geotech Report Final.pdfGeotechnical Engineering Services
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February 1, 2014
Earth Science + Technology
Geotechnical Engineering Services
30th Street NE Area Flooding, Phase 1
Auburn, Washington
for
Otak, Inc. and the City of Auburn
February 13, 2014
8510 154th Avenue NE
Redmond, Washington 98052
425.861.6000
February 13, 2014 | Page i
File No. 0153-040-00
Table of Contents
INTRODUCTION AND PROJECT UNDERSTANDING ..................................................................................... 1
SCOPE OF SERVICES .................................................................................................................................... 1
FIELD EXPLORATION AND LABORATORY TESTING .................................................................................... 3
Field Explorations ................................................................................................................................... 3
Laboratory Testing ................................................................................................................................. 3
PREVIOUS STUDIES ...................................................................................................................................... 3
SITE CONDITIONS .......................................................................................................................................... 3
Geology ................................................................................................................................................... 3
Surface Conditions ................................................................................................................................. 3
Subsurface Soil and Groundwater Conditions ..................................................................................... 4
General ............................................................................................................................................ 4
Pavement Section ........................................................................................................................... 4
Fill……….. .......................................................................................................................................... 4
Alluvial Deposits .............................................................................................................................. 4
Groundwater Conditions ................................................................................................................. 4
CONCLUSIONS AND RECOMMENDATIONS ................................................................................................ 5
General ................................................................................................................................................... 5
Earthquake Engineering ........................................................................................................................ 6
General ............................................................................................................................................ 6
Surface Fault Rupture ..................................................................................................................... 6
Liquefaction ..................................................................................................................................... 6
Temporary Shoring Support and Excavations ...................................................................................... 7
General ............................................................................................................................................ 7
Temporary Cut Slopes ..................................................................................................................... 8
Shored Excavations ......................................................................................................................... 8
Temporary Dewatering........................................................................................................................... 9
General ............................................................................................................................................ 9
Pumped Wells ................................................................................................................................ 10
Well Points ..................................................................................................................................... 10
Open Pumping ............................................................................................................................... 10
Other Shoring and Dewatering Considerations – Retirement Facility .............................................. 11
Pipeline Design .................................................................................................................................... 11
Earth Pressures ............................................................................................................................. 11
Pipe Bedding ................................................................................................................................. 11
Trench Backfill ............................................................................................................................... 12
Excavation Backfill ............................................................................................................................... 12
General .......................................................................................................................................... 12
Re-use of On-Site Soils .................................................................................................................. 12
Structural Fill Placement and Compaction .................................................................................. 12
Manhole Structures ............................................................................................................................. 13
General .......................................................................................................................................... 13
Foundation Support ...................................................................................................................... 13
Manhole Backfill ............................................................................................................................ 14
Lateral Earth Pressures ................................................................................................................ 14
Hydrostatic Uplift ........................................................................................................................... 14
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File No. 0153-040-00
Table of Contents (continued)
Drainage and Erosion Measures......................................................................................................... 15
LIMITATIONS ............................................................................................................................................... 15
REFERENCES .............................................................................................................................................. 16
LIST OF FIGURES
Figure 1. Vicinity Map
Figures 2 through 4. Site Plan
APPENDICES
Appendix A. Field Explorations
Figure A-1 – Key to Exploration Logs
Figures A-2 through A-6 – Log of Explorations
Figures A-7 and A-8 – Sieve Analysis Results
Appendix B. Previous Studies
Appendix C. Report Limitations and Guidelines for Use
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
February 13, 2014 | Page 1
File No. 0153-040-00
INTRODUCTION AND PROJECT UNDERSTANDING
This report presents the results of our geotechnical engineering services for the 30th Street NE Area
Flooding, Phase 1 project for the City of Auburn, Washington. The proposed location of the project
is shown in the Vicinity Map, Figure 1 and in the Site Plans, Figures 2 through 4.
We understand that the existing 30-inch-diameter gravity storm drain system that runs eastward
along 30th Street NE from approximately 375 feet west of the intersection of “C” Street NE and
30th Street NE to the Brannon Park Pump Station (BPPS) structure located northeast of Brannan
Park is currently capacity limited and contributes to local flooding. The proposed improvements
include installation of a new 42-inch storm line to replace the 30-inch line. Along 30th Street NE,
the 30-inch line will be removed and replaced with the 42-inch line. Between “I” Street NE and the
BPPS structure, the 30-inch line will be abandoned in-place and a new 42-inch line will be installed
near to and parallel to the 30-inch line, but within the park boundaries to reduce impacts
to adjacent private properties. The total project length is about 3,700 feet. We understand that
the pipeline will be about 8 to 12 feet deep along 30th Street NE and “I” Street NE. The pipeline
will extend deeper east of “I” Street NE as the tie in to the existing pump station will be about
18 feet deep.
SCOPE OF SERVICES
Our services were completed in general accordance with the Subconsultant Agreement between
Otak, Inc. (Otak) and GeoEngineers, Inc. (GeoEngineers) executed on February 22, 2013. The
purpose of our geotechnical engineering services was to evaluate subsurface soil and groundwater
conditions as a basis for providing geotechnical recommendations for earthwork and site
preparation, trench backfill, construction of temporary cut slopes and shoring systems, control of
ground water during excavation, and pipe support considerations. Our specific scope of services
included the following tasks:
1. Review Previous Geologic and Subsurface Information
Review subsurface information in our files, our previous BPPS geotechnical report, and other
available geotechnical subsurface information in the vicinity regarding subsurface soil and
groundwater conditions.
2. Plan the Exploration Program and Obtain Permits
a. Complete a site visit to locate the proposed borings, plan the traffic control operations,
and develop permit applications.
b. Submit permit applications, traffic control plans, and boring exploration plans to the
City of Auburn, as appropriate.
3. Field Explorations and Laboratory Testing
a. Complete a site visit to meet with utility representatives and clear boring locations.
This will include subcontracting a private utility locator to aid in locating utilities near
the planned boring locations.
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b. Explore subsurface soil and groundwater conditions at the site by drilling five borings
to depths of 16½ to 26½ feet. Install piezometers in two of the borings for
subsequent groundwater monitoring.
c. Read the piezometers one additional time prior to completion of our report.
d. Perform laboratory tests on representative samples of the soils, including tests for
moisture content, density, and particle size distribution.
e. Evaluate pertinent physical and engineering characteristics of the soils based on the
results of the field exploration, laboratory testing and our experience.
4. Provide Geotechnical Design Recommendations
a. Describe site conditions including detailed subsurface soil conditions encountered
based on the results of Tasks 1 and 3 above. A geologic description of the area will be
provided based on published information and our experience in the area.
b. Provide recommendations for earthwork and site preparation including suitability of
on-site soils for reuse in trench backfill, placement and compaction of trench backfill,
and mitigation of unsuitable soil conditions. This will include an evaluation of the
effects of weather and/or construction equipment on site soils.
c. Perform engineering analyses and provide conclusions and recommendations for
conventional trenching techniques including the following:
Geotechnical parameters for trench shoring design including lateral pressures,
and partial shoring considerations;
Excavation and temporary slope considerations;
Pipe support including bedding and backfilling; and
Construction dewatering considerations including depth to groundwater and
estimated permeability coefficients based on laboratory sieve analyses.
d. Provide recommendations for erosion control during construction.
5. Geotechnical Communications, Design Report and Meetings
a. Provide a summary of subsurface conditions encountered as information becomes
available, and attend one or two design team meetings, as requested.
b. Prepare a written report presenting our conclusions and recommendations along with
supporting boring logs, laboratory data, and other appropriate figures.
6. Plans and Specifications Review
a. Review plans and specifications and provide comments and additions with respect to
geotechnical considerations.
7. Construction Support
a. Complete periodic site visits during construction to observe if the construction is
proceeding in accordance with the plans and our recommendations, and to provide
additional recommendations for pipeline support, if required. We assume that up to
four site visits will be requested during construction.
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
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FIELD EXPLORATION AND LABORATORY TESTING
Field Explorations
Subsurface conditions were explored by drilling five borings, designated B-1 through B-5.
The borings were completed to depths of 16½ to 26½ feet below the existing ground surface (bgs)
using trailer-mounted, continuous-flight, hollow-stem auger drilling equipment. Piezometers were
installed in two of the borings, B-1 and B-5, and thus these two borings are also referred to as
monitoring wells.
The locations of the explorations completed for this project are presented on the Site Plan,
Figures 2 through 4. Details of the field exploration program and logs of the explorations are
presented in Appendix A.
Laboratory Testing
Soil samples were obtained during the exploration program and taken to our laboratory for further
evaluation. Selected samples were tested for the determination of moisture content, gradation
characteristics, and Atterberg limits (plasticity characteristics). A description of the laboratory
testing and the test results are presented in Appendix A.
PREVIOUS STUDIES
We reviewed the logs of borings and test pits previously completed by GeoEngineers and others
near the project alignment. The approximate locations of the closest explorations are shown on
the Site Plans, Figures 2 through 4. The boring and test pit logs from these studies are presented
in Appendix B.
SITE CONDITIONS
Geology
Published geologic information for the project vicinity includes a geologic map of the Auburn
quadrangle (Mullineaux, 1965). The surface geologic unit in the project area is alluvium (Qaw)
deposited by the Green River. Alluvium is composed of silt, sand and gravel deposited in
streambeds and fans. The recent alluvium is located in the Green River valley and is likely
underlain by Quaternary-age river and glacial deposits from the Vashon Stade of the Fraser
Glaciation. Features and deposits formed during the Vashon Stade and Frasier glaciations include
recessional outwash deposits composed of sand and gravel, lacustrine (lake deposited) clay, silt
and sands, and glacial till deposits composed of compacted mixtures of clay, silt, sand, gravel and
boulders.
Surface Conditions
The new storm line alignment begins on 30th Street NE north of the airport and extends to the east
within the road right-of-way to “I” Street NE. Near the intersection with “I” Street NE, the new storm
line will turn to the south for about 100 to 150 feet, then turn to the east and traverse along a
private driveway adjacent to a retirement facility and continue east through Brannan Park.
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
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The new storm line will tie into the existing pump station located northeast of the northeast corner
of the park.
The existing ground surface is relatively level along the project alignment. The streets are paved
with asphalt concrete. The park is grass covered with an asphalt trail extending along the northern
boundary close to the proposed pipe alignment. Groups of conifers are present between the trail
and the north boundary of the park. Site features are shown in the Site Plans, Figures 2 through 4.
Subsurface Soil and Groundwater Conditions
General
Our borings encountered a variable pavement section, where located in the existing roadways,
overlying fill and/or river alluvium. Subsurface soils encountered in our explorations are consistent
with the geologic mapping, mainly consisting of alluvial deposits ranging from silt to sand with
varying amounts of gravel. The alluvium becomes more granular and cleaner (that is, contains less
percent fines and silt) in the eastern portion of the alignment. Each of these units is discussed in
more detail below:
Pavement Section
Three of our borings were completed within existing roadways and encountered a variable
thickness of asphalt concrete surfacing. We encountered a 6- to 9-inch thickness of asphalt
concrete. A 3-inch-thick layer of base course was encountered beneath the asphalt in the borings.
Fill
Boring B-1, located on 30th Street NE west of Auburn Way, encountered very dense fill consisting of
silty gravel with sand and cobbles. Although the remaining borings did not encounter fill, we
anticipate that portions of the existing roadways are underlain by fill which may be variable in
density and type of soil.
Alluvial Deposits
Most of the borings encountered soft to medium stiff silt and sandy silt interbedded with loose silty
sand in the upper portion of the boring. Cleaner loose to medium dense sand was encountered
below these upper siltier deposits at a depth of 15 to 17 feet in borings B -2 and B-3, respectively.
Boring B-1 did not encounter cleaner sand at the depth explored (16.5 feet), but based on nearby
borings completed by others, we anticipate that cleaner sand deposits may be present below the
depth explored.
Borings B-4 and B-5, located in Brannan Park, encountered medium dense clean sands and
gravels at depths of 8 and 13 feet, respectively. The boring completed for the original pump
station encountered clean sand below a depth of 10 feet. All of the borings with the exception of
boring B-1 terminated in these cleaner sand and gravel deposits.
Groundwater Conditions
We observed groundwater at depths between approximately 5 and 10 feet during drilling.
Groundwater was measured at a depth of 4.7 feet in monitoring well B-1 and at a depth of 6 feet in
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monitoring well B-5, 3 days after completing the drilling. Based on our experience in this area,
we anticipate that ground water is within about 5 feet of the surface during the wet winter and
spring months, and somewhat lower during the remainder of the year. Groundwater is expected to
fluctuate as a function of season, precipitation, and rise and fall of the nearby Green River.
CONCLUSIONS AND RECOMMENDATIONS
General
We conclude that the new storm sewer replacement can be satisfactorily completed with
conventional earthwork equipment and techniques. Our explorations typically encountered upper
deposits of silt and silty sand underlain by cleaner sand and gravel deposits. A summary of the
primary site preparation and design considerations for the proposed project is provided below.
The summary is presented for introductory purposes only and should be used in conjunction with
the complete recommendations presented in this report. Recommendations for shoring are
discussed in detail in a following section.
■ Excavation in the soils can be accomplished with conventional equipment, but will require
shoring to limit the excavation in the roadways and also likely required in the park due to the
presence of loose to medium dense sand and gravel deposits that would require flatter slopes
for long-term stability, as discussed below.
■ Subsurface conditions along the pipe invert are anticipated to consist of soft to medium stiff
silt and loose sand west of “I” Street NE and loose to medium dense sand and gravel east of
“I” Street NE.
■ Dewatering using pumped wells or well points will be necessary for the eastern portion of the
project, and likely necessary for all of the portion east of Auburn Way, to prevent failure of the
excavation bottom due to heave or boiling of the underlying cleaner sand deposits. The
dewatering should be fully functional and the site dewatered prior to beginning the excavation
and should be used until the pipeline is completely backfilled. Dewatering considerations are
discussed in a following section.
■ Sheet piles or other types of positive shoring support will be required where the excavation is
close to the existing retirement facility foundations.
■ Where open cuts may be feasible, assuming the site soils are dewatered prior to excavation,
we recommend temporary slopes be inclined at 1½H:1V (horizontal to vertical) or flatter at the
site. These slopes may need to be modified depending on the excavation depth, seepage
conditions, localized sloughing, and dewatering methods utilized during construction.
■ The subsurface soils contain a high percentage of fines (silt and clay) and are therefore
moisture-sensitive. The upper silt soils will not be suitable for reuse as trench backfill.
The underlying sand and gravel will not be suitable for use as structural fill or trench backfill
during the wet weather. Therefore, we recommend import fill be available for the majority, if
not all, of the trench backfill.
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Earthquake Engineering
General
The seismic design of the proposed improvements can be completed using the design criteria
presented in the American Association of State Highway and Transportation Officials (AASHTO)
seismic design information. The AASHTO Guide Specifications recommend a 7 percent probability
of exceedance in 75 years (nominal 1,000-year earthquake) design event for development of
a design spectrum. Based on these criteria, we recommend the parameters for site class,
seismic zone, acceleration coefficient and spectral acceleration coefficients presented in the
following table.
TABLE 1. AASHTO SEISMIC PARAMETERS
AASHTO Seismic Parameter Recommended Value
Site Class D
Seismic Design Category (SDC) for 0.30 < SD1 ≤ 0.50 D
Effective Peak Ground Acceleration Coefficient
AS = FpgaPGA = (1.09)(0.408) 0.445
Design Spectral Acceleration Coefficient at 0.2 Second period
SDS = FaSs = (1.138)(0.906) 1.03
Design Spectral Acceleration Coefficient at 1.0 Second period
SD1 = FvS1 = (1.797)(0.302) 0.542
Surface Fault Rupture
Based on our knowledge of regional geology in the vicinity of the site, distance to known active
faults, and the substantial thickness of glacial and postglacial sediments beneath the sit e, we
conclude that the potential for surface fault rupture is remote.
Liquefaction
Liquefaction is a phenomenon where soils experience a rapid loss of internal strength as pore
water pressures increase in response to strong ground shaking. The increased pore water
pressure may temporarily meet or exceed soil overburden pressures to produce conditions that
allow soil and water to flow, deform, or erupt from the ground surface. Ground settlement, lateral
spreading and/or sand boils may result from soil liquefaction. Structures supported on or within
liquefied soils may suffer foundation settlement or lateral movement that can be damaging to the
buildings. Based on our analyses, the potential exists for liquefaction within zones of the loose to
medium dense sand deposits encountered in the boring completed at the site.
The evaluation of liquefaction potential depends on numerous site parameters, including soil grain
size, soil density, site geometry, static stresses and the design ground acceleration. Typi cally, the
liquefaction potential of a site is evaluated by comparing the cyclic shear stress ratio (the ratio
of the cyclic shear stress to the initial effective overburden stress) induced by an earthquake to
the cyclic shear stress ratio required to cause liquefaction. The resistance to liquefaction
and estimated ground settlements resulting from earthquake-induced liquefaction was analyzed
using empirical procedures by Tokimatsu and Seed (1987) that relate settlement to the standard
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
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File No. 0153-040-00
penetration test (SPT) data. Liquefaction potential of the site soils was evaluated using a design
acceleration equal to the effective peak ground accelerations coefficient provided above in
Table 1.
Analysis of the SPT data indicates that there is a potential for liquefaction within portions of the
alluvial deposits in the upper 20 to 40 feet (based on the boring completed for the pump station
which terminated at a depth of 47½ feet). Liquefaction-induced free-field ground settlement of the
potentially liquefiable zones above a depth of 40 feet is estimated to be up to 6 inches for a
design-level earthquake. However, as the depth of the pipeline and associated manholes will be
close to a depth of 10 to 18 feet, the potential for liquefaction and liquefaction-induced settlement
will be somewhat less.
The magnitude of liquefaction-induced ground settlement will vary as a function of the
characteristics of the earthquake (earthquake magnitude, location, duration and intensity) and the
groundwater conditions at the time of the earthquake.
The design and construction procedures discussed in this report will not mitigate the possible
liquefaction effects and associated damage to the pipe caused by differential settlements, should
they occur. In order to reduce the risk of potential damage from liquefaction, it would be necessary
to support the pipe and manhole structures on piles or improved ground such that the soils below
the corridor do not liquefy. However, in our experience, very few pipe alignments are designed to
mitigate liquefaction because of the significant costs for mitigation.
Temporary Shoring Support and Excavations
General
Shoring and temporary slope inclinations must conform to the provisions of Title 296 Washington
Administrative Code (WAC), Part N, “Excavation, Trenching and Shoring.” The soils encountered at
the site are classified as Type C soil in accordance with the provisions of Title 296-155 WAC,
Part N, “Excavation, Trenching, and Shoring.” Regardless of the soil type encountered in the
excavation, shoring, trench boxes or sloped sidewalls will be required under Washington Industrial
Safety and Health Act (WISHA). The contract documents should specify that the contractor is
responsible for selecting excavation and dewatering methods, monitoring the excavations for
safety and providing shoring, as required, to protect personnel and structures.
Excavation, shoring, and construction dewatering activities must be coordinated to ensure
successful harmonization of the efforts and to avoid conflicts.
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Temporary Cut Slopes
In general, temporary cut slopes should be inclined no steeper than about 1½H:1V above the
groundwater table. This guideline assumes that all surface loads are kept at a minimum distance
of at least one half the depth of the cut away from the top of the slope and that significant seepage
is not present on the slope face. In our opinion, any excavations below the water table will be very
unstable and will either require temporary shoring or dewatering, or both, to complete the
excavations successfully. Even with dewatering, some sloughing and raveling of the temporary
slopes should be expected. For open cuts at the site we recommend that:
■ Construction traffic, equipment, stockpiles or building supplies not be allowed within a distance
of 5 feet from the top of the cuts.
■ Exposed soil along the slopes be protected from surface erosion using waterproof tarps or
plastic sheeting.
■ Surface water is diverted away from the open excavations.
■ The general condition of the slopes be observed periodically by a geotechnical engineer to
confirm adequate stability.
If temporary cut slopes experience excessive sloughing or raveling during construction, it may
become necessary to modify the cut slopes to maintain safe working conditions and protect
adjacent facilities or structures. Slopes experiencing excessive sloughing or raveling can be
flattened, supported with shoring, or additional dewatering can be provided if the poor slope
performance is related to groundwater seepage.
Shored Excavations
Excavations deeper than 3 feet should be shored or laid back at a stable slope if workers are
required to enter. Below the groundwater table, caving should be anticipated and thus shoring will
be required. Because of the diversity of available shoring systems and construction techniques,
the design of temporary shoring is most appropriately left up to the contractor proposing to
complete the installation. However, we recommend that the shoring be designed by a Professional
Engineer (PE) licensed in the State of Washington, and that the PE-stamped shoring plans and
calculations be submitted to the City of Auburn and the Engineer for review prior to construction.
The following paragraphs present general recommendations for the type of shoring system and
design parameters that we conclude are appropriate for the subsurface conditions at the project.
We anticipate that the excavations will be shored using trench boxes, conventional sheet piles, a
braced system, or a slide rail system. The lateral soil pressures acting on temporary supports will
depend on the nature and density of the soil behind the wall, the inclination of the ground surface
behind the wall, and the groundwater level. For walls that are free to yield at the top at least one
thousandth of the height of the wall (i.e., wall height times 0.001), soil pressures will be less than if
movement is restrained. The design of temporary shoring should allow for lateral pressures
exerted by the adjacent soil, and for surcharge loads resulting from structures, traffic, construction
equipment, temporary stockpiles adjacent to the excavation, etc. Lateral load resistance can be
mobilized through the use of braces, tiebacks, anchor blocks and passive pressures on members
that extend below the bottom of the excavation. Temporary shoring used to support trench
excavations typically uses internal bracing such as hydraulic shoring or trench boxes.
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We recommend that yielding walls retaining native soils be designed using an equivalent fluid
density of 40 pounds per cubic foot (pcf), for horizontal ground surfaces. For non-yielding
(i.e., braced) systems, we recommend that the shoring be designed for a uniform lateral pressure
of 26*H in pounds per square foot (psf), where H is the depth of the planned excavation in feet
below a level ground surface. These values assume that the ground behind the shoring has been
dewatered such that the ground water table is at least 2 feet below the base of the excavation.
Temporary dewatering recommendations are discussed in a subsequent section of this report.
If the dewatering system is not designed to lower the groundwater level behind the shoring walls
(e.g. sheet pile walls with dewatering system inside the shored excavation), hydrostatic pressures
must be included in the shoring design. For this condition, temporary shoring should be designed
using a lateral pressure equal to an equivalent fluid density of 85 pcf, for horizontal ground
conditions adjacent to the excavation.
The above lateral soil pressures do not include traffic, structure or construction surcharges that
should be added separately, if appropriate. Shoring should be designed for a traffic influence
equal to a uniform lateral pressure of 100 psf acting over the depth of the trench. More
conservative pressure values should be used if the designer deems them appropriate.
The soil pressure available to resist lateral loads against shoring is a function of the passive
resistance that can develop on the face of below-grade elements of the shoring as those elements
move horizontally into the soil. The allowable passive resistance on the face of embedded shoring
elements may be computed using an equivalent fluid density of 1 60 pcf for native soils below the
water table. This passive equivalent fluid density value includes a factor of safety of about 1.5.
Temporary Dewatering
General
The purpose of this report section is to present geotechnical and hydrogeological data that will
influence temporary construction dewatering and to describe in general terms various types
of dewatering techniques that may be feasible at the site. Detailed dewatering designs for
construction are not within our scope of services.
As discussed above, static groundwater was measured at 4.7 feet in monitoring well B-1 and at a
depth of 6 feet in monitoring well B-5. Most of the soils along the alignment consist of siltier soils
underlain by clean sand deposits which may be under some pressure. This sequence of soils can
result in failure of the excavation bottom if the area is not adequately dewatered. Therefore, it will
be critical to implement a dewatering program which can lower the groundwater level to a
minimum of 2 feet below the lowest anticipated level of excavation prior to beginning excavating.
We recommend the groundwater level be maintained a minimum of 2 feet below the bottom of the
lowest point of the excavation during construction or that level necessary to stabilize the shoring.
The level will depend upon the dewatering method, the size of the excavation and other factors.
The dewatering should be maintained until the pipeline is in place and the backfill is within 3 feet
of the surface.
Based on the soil conditions encountered and the planned depth of the storm sewer pipeline, we
anticipate that dewatering using pumped wells or well points will be necessary east of “I” Street NE
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
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and possibly between Auburn Way and “I” Street NE. We recommend that the design of the
dewatering system be performed by an experienced dewatering specialist who is a PE or a
Licensed Hydrogeologist in the State of Washington. The contractor should be required to submit
the proposed dewatering system design and plan layout to the City of Auburn and the Engineer for
review and comment prior to beginning construction.
The level of effort required for dewatering will depend to some extent on the time of year during
which construction is accomplished. Less seepage into the work areas, especially west of
Auburn Way, should be expected if construction is accomplished in the late summer or early fall
months, and correspondingly, more seepage should be expected during the wetter periods of the
year. However, even during the drier months we anticipate that the sand and gravel deposits
encountered in Brannan Park will be saturated and produce significant water during dewatering.
A general discussion of the dewatering methods anticipated for the project is presented below.
Pumped Wells
Individually pumped wells may be considered for dewatering the construction areas. Pumped wells
that have been properly installed and developed are capable of producing the high discharge rates
that are necessary to dewater highly permeable sand deposits. Pumped wells are generally the
most effective dewatering method in areas where dewatering to deeper than about 20 feet bgs is
necessary.
We recommend that all dewatering wells installed for this project be properly developed to remove
fine sediment from the immediate vicinity of the well screens. Proper development is essential for
producing efficient wells and greatly reduces the turbidity of the water discharged from the well.
Filter packs consisting of graded sand, or sand and fine gravel should be installed around the well
screens in areas where the aquifer contains a high percentage of fine sand and silt.
Well Points
Well points are effective for dewatering all types of soils, whether pumping small amounts of water
from silt or large quantities of water from coarse sand and gravel. The volume of water generated
by a well point system is typically less than the volume generated by a corresponding system of
pumped wells because the well points are generally completed at a shallower depth. Because of
the shallower completion depth, the volume of aquifer that contributes water to a well point system
is less than for a comparable deep well system.
Well point systems are most suitable for dewatering shallow excavations where the water table
must be lowered no more than about 20 feet bgs. Multiple well point stages are generally required
beyond that depth because of the physical limitations of suction lift.
Open Pumping
This dewatering method involves removing water that has seeped into the excavation by pumping
from a sump that has been excavated at one end of the excavation or trench. Drainage ditches
that are connected to the sump are typically excavated along the sidewalls at the base of the
excavation or trench. The excavation for the sump and the drainage ditches should be backfilled
with gravel or crushed rock to reduce the amount of erosion and associated sediment in the water
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pumped from the sump. In our experience, a slotted casing or perforated 55-gallon drum that is
installed in the sump backfill provides a suitable housing for a submersible pump.
The amount of water removed from the excavation by open pumping should be minimized because
of high turbidity levels. Temporary storage of dewatering effluent from the sumps in a settlement
tank or basin may be required to meet discharge permit requirements and reduce sediment
content prior to discharging the water to surface water courses. In general, we do not believe that
open pumping will adequately dewater most of the alignment, particularly the east side of the
alignment.
Other Shoring and Dewatering Considerations – Retirement Facility
We understand that the new storm line will be about 7 feet horizontally from the north side of the
existing retirement facility. We recommend that a positive type of shoring such as sheet piles or a
slide rail system be used where the bottom of the excavation extends below a 45 degree line
extending outward from the existing foundations. The use of sheet piles with well points inside of
the sheets would reduce the risk of settlement due to dewatering. Alternatively, the dewatering
and excavation and backfill along this segment could be done sequentially to limit the time
dewatering is required. We recommend that a survey along the north side of the building be
completed prior to beginning dewatering and shoring, and that at least two settlement survey
points be established and surveyed prior to beginning construction. These survey points should be
monitored on a daily basis during installation of the storm line near the building. If sheet piles are
used, the residences of the building should be informed that some vibrations will likely be felt
during the installation process.
Pipeline Design
Earth Pressures
We recommend that the pipeline be designed considering the full weight of the overburden soils
above the pipes. The overburden soil weight can be evaluated assuming a n average total unit
weight of 125 pcf. Resistance to uplift below groundwater can be developed by the dead weight of
the structure and friction along the sides of the structure. Frictional resistance can be computed
using a coefficient of friction of 0.40 applied to the lateral soil pressures. This coefficient of friction
is an allowable value and includes a factor of safety. We recommend that lateral soil pressures for
uplift resistance be computed using an equivalent fluid density of 18 pcf. This value assumes the
groundwater table is above the pipeline.
Pipe Bedding
We recommend that all structural fill placed as pipe bedding meet the criteria for gravel backfill for
pipe zone bedding as described in Section 9-03.12(3) of the 2012 Washington State Department
of Transportation (WSDOT) Standard Specifications. Pipe bedding material should be placed in
accordance with WSDOT Standard Specification 7-08.3(1)C. Where soft or loose soils are
encountered below the pipe alignment, we recommend they be removed to a depth of 12 inches
below the invert, or to firm material as directed by the engineer.
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
Page 12 | February 13, 2014 | GeoEngineers, Inc.
File No. 0153-040-00
Trench Backfill
We recommend that trench backfill be compacted as recommended in the “Excavation Backfill”
section of this report. A geotechnical engineer should observe the preparation for, placement, and
compaction of structural fill. An adequate number of in -place density tests should be performed in
the fill to evaluate if the specified degree of compaction is being achieved.
Excavation Backfill
General
All backfill should consist of clean sand or sand and gravel, or the moisture conditioned on-site
soils compacted as described below. As discussed below, re-use of a portion of the existing native
sand deposits might be feasible based on the existing moisture content, while the native silt will
not be practical for use as structural fill. Re-use of the on-site soils will only be feasible in dry
weather conditions. We suggest import fill be available for the majority of trench backfill.
Re-use of On-Site Soils
Most of the existing native soils tested have moisture contents above the optimum content
required for adequate compaction. The upper 5 to 10 feet of on-site soils have a high percentage
of fines (silt) and will not be suitable for use as trench backfill material. The remainder of sand
soils excavated above the water table might be suitable for use as trench backfill during dry
weather. The sand material excavated below the water table will need to be drained of excess
water prior to use.
Structural Fill Placement and Compaction
Structural fill soil must be free of significant debris, organic contaminants and rock fragments
larger than 6 inches. The suitability of soil for use as structural fill will depend on its gradation and
moisture content. As the amount of fines (soil particles passing U.S. Standard No. 200 sieve)
increases, the soil becomes more sensitive to small changes in moisture content and adequate
compaction becomes more difficult to achieve. Structural fill placed during wet weather or on wet
subgrades should contain no more than 5 percent fines. During dry weather, the fines content may
be higher, provided the fill is at a suitable moisture content, or can be moisture-conditioned, and
compacted to the specified degree.
Structural fill should be mechanically compacted to a firm, non-yielding condition. The structural fill
should be placed in lifts not exceeding 1 foot in thickness. Each lift should be conditioned to the
proper moisture content and compacted to the specified density before placing subsequent lifts.
Structural fill should be compacted to the following criteria:
1. Pipe bedding material should be placed in accordance with WSDOT Standard Specifications
Section 7-08.3(1)C. This bedding material should be compacted by tamping. Where soft or
loose soils are encountered below the pipe alignment, we recommend they be removed to a
depth of 12 inches below the invert, or to firm material as directed by the engineer.
2. Backfill placed above the bedding material should consist of on-site material that is of
structural fill quality, or imported granular material that meets the criteria for common borrow
as described in WSDOT Standard Specifications Section 9-03.14(3). Common borrow will be
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
February 13, 2014 | Page 13
File No. 0153-040-00
suitable for use as structural fill during dry weather conditions only. If structural fill is placed
during wet weather, the structural fill should meet the criteria for gravel borrow as described in
WSDOT Standard Specification Section 9-03.14(1), with the exception that the fines content
(portion passing the U.S. No. 200 sieve) be reduced to 5 percent maximum.
3. All trench backfill placed outside of roadways should be compacted in lifts to at least
90 percent of the maximum dry density (MDD) determined in general accordance with the
American Society for Testing and Materials (ASTM) D 1557 test procedure.
4. All trench backfill placed under roadways or sidewalks should be compacted to at least
95 percent of MDD (ASTM D 1557) within the uppermost 2 feet of the trench. Fill and trench
backfill below 2 feet should be compacted to at least 90 percent of the MDD (ASTM D 1557).
5. Structural fill placed for crushed surfacing base course below pavements should be compacted
to at least 95 percent of the MDD (ASTM D 1557).
We recommend that a geotechnical engineer observe the preparation for, placement, and
compaction of structural fill. An adequate number of in -place density tests should be performed in
the fill to evaluate if the specified degree of compaction is being achieved.
Manhole Structures
General
We anticipate that new manhole structures will be about 12 to 18 feet below existing grades.
We anticipate that loose to medium dense sand will be exposed at the bottom of most of these
excavations.
Foundation Support
We recommend that the manholes be supported on a 1-foot-thick pad of 1¼ minus crushed rock
or 2- to 4-inch quarry spalls to provide a stable base for the manholes. A nonwoven geotextile
(Mirafi 600X or equivalent) may need to be placed across the bottom of the excavation prior to
placing the crushed rock or quarry spalls, depending on the conditions along the exposed bottom.
The crushed rock or quarry spalls should be tamped or rolled to the extent possible.
All loosened soils should be removed or compacted to the extent possible prior to placing the
crushed rock.
Below-grade facilities can be designed using an allowable soil bearing of 2,000 psf provided all
loosened soils have been removed or recompacted and 12 inches of crushed rock placed as
recommended above. We recommend the geotechnical engineer evaluate the exposed subgrade
to confirm conditions are as assumed during design and provide modified recommendations, if
appropriate.
We estimate that settlement of manholes supported as recommended above in this report should
be less than about 1 inch. To reduce the potential for differential settlement between the
manholes and pipeline, the contractor should use special care when preparing the manhole
subgrade, and compacting the backfill and pipe bedding material where the pipeline enters and
exits the manhole.
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
Page 14 | February 13, 2014 | GeoEngineers, Inc.
File No. 0153-040-00
All manholes should be designed with a sufficient safety factor to resist flotation.
Manhole Backfill
We recommend that all backfill placed around the manholes be placed as structure fill meeting the
requirements described above in the “Excavation Backfill” section of this report.
Lateral Earth Pressures
We recommend that permanent below grade manhole structures be designed for lateral pressures
corresponding to at rest soil pressure. As the groundwater table can be at or near the surface, we
recommend designing the walls using the buoyant density of the soil plus the full hydrostatic water
pressure. For this condition, we recommend that the walls be designed using a lateral equivalent
fluid density equal to 85 pcf.
We recommend that seismic loading against the manhole walls be approximated using a uniform
lateral pressure equal to 7H psf, where H is the depth in feet of the structure. This seismic lateral
pressure is in addition to and should be superimposed upon the static soil and hydrostatic
pressures given previously.
These lateral soil pressures do not include traffic or other surcharges that should be added
separately, if appropriate. Surcharge loads should be included as appropriate.
The soil pressure available to resist lateral loads is a function of the frictional resistance against
the vault base and the passive resistance that can develop on the face of below -grade elements of
the structure as those elements move horizontally into the soil. For manhole foundations bearing
on compacted crushed rock or quarry spalls prepared as recommended in this report, an allowable
coefficient of sliding friction of 0.4 between concrete and the compacted crushed rock or quarry
spalls. The allowable passive resistance on the face of embedded foundation elements may be
computed using an equivalent fluid density of 160 pcf assuming the backfill and surrounding
native soils have the potential to become saturated.
Hydrostatic Uplift
The base of the manholes will extend below the typical groundwater levels: therefore, buoyancy
and uplift must be evaluated. Resistance to uplift may be developed by the dead weight of the
structure and friction along the sides of the structure, and/or by the weight of backfill soils above
an exterior perimeter lip added to the foundation slab. Frictional resistance may be computed
using a coefficient of friction of 0.40 applied to the lateral soil pressures assuming the vaults are
backfilled as recommended above. This coefficient of friction is an allowable value and includes a
factor of safety. We recommend that lateral soil pressures for uplift resistance be computed using
an equivalent fluid density of 18 pcf. This value assumes the groundwater table is near the
surface. We do not recommend use of side frictional resistance during seismic events due to the
potential for loss of soil strength due to liquefaction. If additional uplift resistance is required
during a design seismic event, we recommend adding an exterior perimeter lip to the base of the
manholes, and using the weight of the backfill soil above the perimeter lip for resistance.
The weight of the backfill soil should be based an average buoyant soil density of 60 pcf. We
recommend that a minimum factor of safety of 1.5 be used in designing against hydrostatic uplift.
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
February 13, 2014 | Page 15
File No. 0153-040-00
Drainage and Erosion Measures
Potential sources or causes of erosion and sedimentation depend upon construction methods,
slope length and gradient, amount of soil exposed and/or disturbed, soil type, construction
sequencing and weather. The project impact on erosion-prone areas can be reduced by
implementing an erosion and sedimentation control plan. The plan should be designed in
accordance with applicable provisions of the City of Auburn Code. Site monitoring should be
performed by qualified personnel to evaluate the effectiveness of the erosion control measures
and repair and/or modify them as appropriate. Provisions for modifications to the erosion control
system based on monitoring observations should be included in the plan. The plan should
incorporate basic planning principles including:
■ Prevent erosion from occurring by minimizing the area of vegetative disturbance, providing
blanket protection of disturbed areas, and grading to avoid concentration of surface runoff
onto or off of cut or fill slopes or natural slopes.
■ Intercept surface runoff onto or off of disturbed areas to control sediment transport. This may
be accomplished by use of interceptor swales, perimeter dikes, brush barriers, etc.
■ Provide redundancy in erosion control facilities.
■ Implement permanent erosion control facilities and hydroseed all finished slopes as soon as
practical during the project. Temporary erosion protection may be necessary until permanent
erosion protection is established.
LIMITATIONS
We have prepared this report for the exclusive use of City of Auburn, Otak, and their authorized
agents for the project site. The data should be provided to prospective contractors for their bidding
or estimating purposes, but our report and interpretations should not be construed as a warranty of
the subsurface conditions.
Within the limitations of scope, schedule and budget, our services have been executed in
accordance with generally accepted practices in the field of geotechnical engineering in this area
at the time this report was prepared. No warranty or other conditions, express or implied, should
be understood.
Any electronic form, facsimile or hard copy of the original document (email, text, table, and/or
figure), if provided, and any attachments are only a copy of the original document. The original
document is stored by GeoEngineers, Inc. and will serve as the official document of record.
Please refer to Appendix C, “Report Limitations and Guidelines for Use” for additional information
pertaining to use of this report.
We appreciate the opportunity to participate on this project. Should you have any questions
concerning this report or if we can be of additional service, please call.
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
Page 16 | February 13, 2014 | GeoEngineers, Inc.
File No. 0153-040-00
REFERENCES
International Code Council, 2009, “International Building Code.”
Tokimatsu, K. and Seed, H.B., August 1987, “Evaluation of Settlement in Sands Due to Earthquake
Shaking,” Journal of Geotechnical Engineering, Vol. 113, No. 8.
U.S. Geological Survey, “Seismic Design Maps and Tools, U.S. Seismic Design Maps.”
http://earthquake.usgs.gov/hazards/designmaps/usdesign.php accessed April 25, 2013.
Mullineaux, D.R., compiler, 1965. Geologic Map of the Auburn Quadrangle, King and Pierce
Counties, Washington: U.S. Geological Survey, Geologic Quadrangle Map GQ-406, scale
1:24,000.
Washington Administrative Code, Title 296, Part N, “Excavation, Trenching and Shoring.”
Washington State Department of Transportation, 2012, “Standard Specifications for Road, Bridge
and Municipal Construction.”
Earth Science + Technology
Type Name of Services Here
Name of Project Here
for
Type Client Name Here
Type Date of Report Here
Isaac Evans ParkIsaac Evans Park
Brannan ParkBrannan Park
Dykstra ParkDykstra Park
Auburn Regional Golf CourseAuburn Regional Golf Course
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Notes:1. The locations of all features shown are approximate.2. This drawing is for information purposes. It is intended to assist in showing features discussed in an attached document. GeoEngineers, Inc. cannot guarantee the accuracy and content of electronic files. The master file is stored by GeoEngineers, Inc. and will serve as the official record of this communication.3. It is unlawful to copy or reproduce all or any part thereof, whether for personal use or resale, without permission.
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Earth Science + Technology
Type Name of Services Here
Name of Project Here
for
Type Client Name Here
Type Date of Report Here
APPENDIX A
Field Explorations and Laboratory Testing
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
February 13, 2014 | Page A-1
File No. 0153-040-00
APPENDIX A
FIELD EXPLORATIONS AND LABORATORY TESTING
Field Explorations
Subsurface conditions were explored at the site by drilling five borings, designated B-1 through B-5.
The borings were completed to depths ranging from 16½ t0 26½ feet below the existing ground
surface. The drilling was performed by Geologic Drill, Inc. under subcontract to GeoEngineers on
April 6 2013. The locations of the explorations were estimated by measuring distances from site
features in the field by taping and pacing and should be considered approximate. The locations
are shown on the Site Plans, Figures 2 through 4.
The borings were completed using trailer-mounted, continuous-flight, hollow-stem auger drilling
equipment. A geotechnical engineer from our firm continually monitored drilling operations,
examined and classified the soils encountered, obtained representative soil samples, observed
groundwater conditions, and prepared a detailed log of each boring.
The soils encountered in the borings were generally sampled at 2½ or 5-foot vertical intervals with
a 2-inch outside diameter split-barrel standard penetration test (SPT) sampler. The samples were
obtained by driving the sampler 18 inches into the soil with a 140 -pound rope and cathead
hammer free-falling 30 inches. The number of blows required for each 6 inches of penetration was
recorded. The blow count ("N-value") of the soil was calculated as the number of blows required for
the final 12 inches of penetration. This resistance, or N-value, provides a measure of the relative
density of granular soils and the relative consistency of cohesive soils. Where very dense
soil conditions preclude driving the full 18 inches, the penetration resistance for the partial
penetration is entered on the logs. The blow counts are shown on the boring logs at the respective
sample depths.
Soils encountered in the explorations were visually classified in general accordance with the
classification system described in Figure A-1. A key to the log symbols is also presented in
Figure A-1. The logs of the explorations are presented in Figures A-2 through A-6. The logs are
based on our interpretation of the field and laboratory data and indicate the various types of soils
and groundwater conditions encountered. The logs also indicate the depths at which these soils or
their characteristics change; although, the change may actually be gradual. If the change occurred
between samples in the borings, it was interpreted. The densities noted on the boring log are
based on the blow count data obtained in the boring and judgment based on the conditions
encountered.
Observations of groundwater conditions were made during drilling. The groundwater conditions
encountered during drilling are presented on the boring logs. Groundwater conditions observed
during drilling represent a short term condition and may or may not be representative of the long
term groundwater conditions at the site. Groundwater conditions observed during drilling should
be considered approximate.
The borings were backfilled in accordance with Washington State Department of Ecology
regulations.
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
Page A-2 | February 13, 2014 | GeoEngineers, Inc.
File No. 0153-040-00
Piezometer Installation
Piezometers (monitoring wells) were installed in two of the borings, B-1 and B-5, following drilling.
The monitoring wells consist of 1-inch-diameter schedule 40 polyvinyl chloride (PVC) pipe.
The lower portion of the pipe is slotted (0.02-inch slot width) to allow entry of water in the well.
Clean 10-20 sand was placed in the borehole annulus surrounding the slotted portion of the PVC
pipe. Bentonite chips were placed above the sand pack to form a surface seal. The monitoring
wells are protected by at-grade steel monuments. Specific information regarding well construction
is shown on the boring logs. Groundwater levels measured in the monitoring wells are presented in
the report text.
Laboratory Testing
General
Soil samples obtained from the explorations were transported to GeoEngineers’ laboratory and
evaluated to confirm or modify field classifications, as well as to evaluate engineering properties of
the soil samples. Representative samples were selected for laboratory testing consisting of
moisture content testing, sieve analyses, and Atterberg limits (plasticity characteristics). The tests
were performed in general accordance with test methods of American Society for Testing and
Materials (ASTM) or other applicable procedures.
Moisture Content Testing
Moisture contents tests were completed in general accordance with ASTM D 2216 for
representative samples obtained from the exploration. The results of these tests a re presented on
the exploration log in Appendix A at the depths at which the samples were obtained.
Sieve Analyses
Full sieve analyses were performed on three selected samples in general accordance with
ASTM D-422. The wet sieve analysis method was used to determine the percentage of soil greater
than the U.S. No. 200 mesh sieve. The results of the sieve analyses were plotted, classified
in general accordance with the Unified Soil Classification System (USCS), and presented in
Figures A-7 and A-8.
Atterberg Limits Testing
Atterberg limits tests were performed on selected fine-grained soil samples. The tests were used
to classify the soil as well as to evaluate index properties. The liquid limit and plastic limit were
estimated through a procedure performed in general accordance ASTM D 4318. The results of the
Atterberg limits tests indicated that the fine-grained soils are non-plastic.
Sheen Classification
NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurface
conditions. Descriptions on the logs apply only at the specific exploration locations and at the time the explorations were made; they are
not warranted to be representative of subsurface conditions at other locations or times.
CC
Asphalt Concrete
NS
SS
MS
HS
NT
Shelby tube
ADDITIONAL MATERIAL SYMBOLS
%F
AL
CA
CP
CS
DS
HA
MC
MD
OC
PM
PI
PP
PPM
SA
TX
UC
VS
Graphic Log Contact
Distinct contact between soil strata or
geologic units
Approximate location of soil strata
change within a geologic soil unit
Approximate location of soil strata
change within a geologic soil unit
Measured groundwater level in
exploration, well, or piezometer
Measured free product in well or
piezometer
GRAPH
Topsoil/
Forest Duff/Sod
Direct-Push
Crushed Rock/
Quarry Spalls
Blowcount is recorded for driven samplers as the number
of blows required to advance sampler 12 inches (or
distance noted). See exploration log for hammer weight
and drop.
A "P" indicates sampler pushed using the weight of the
drill rig.
FIGURE A-1
2.4-inch I.D. split barrel
SYMBOLS TYPICAL
KEY TO EXPLORATION LOGS
CR
Bulk or grab
Piston
Standard Penetration Test (SPT)
DESCRIPTIONSLETTER
Distinct contact between soil strata or
geologic units
TS
GC
PT
OH
CH
MH
OL
GM
GP
GW
DESCRIPTIONS
TYPICAL
LETTER
(APPRECIABLE AMOUNT
OF FINES)
MAJOR DIVISIONS
POORLY-GRADED SANDS,
GRAVELLY SAND
PEAT, HUMUS, SWAMP SOILS
WITH HIGH ORGANIC
CONTENTS
CLEAN SANDS
GRAVELS WITH
FINES
CLEAN
GRAVELS
HIGHLY ORGANIC SOILS
SILTS
AND
CLAYS
SILTS
AND
CLAYS
SAND
AND
SANDY
SOILS
GRAVEL
AND
GRAVELLY
SOILS
(LITTLE OR NO FINES)
FINE
GRAINED
SOILS
COARSE
GRAINED
SOILS
SW
MORE THAN 50%
OF COARSE
FRACTION
RETAINED ON NO.
4 SIEVE
CL
WELL-GRADED SANDS,
GRAVELLY SANDS
SILTY GRAVELS, GRAVEL - SAND
- SILT MIXTURES
LIQUID LIMIT
GREATER THAN 50
SILTY SANDS, SAND - SILTMIXTURES
(APPRECIABLE AMOUNT
OF FINES)
SOIL CLASSIFICATION CHART
LIQUID LIMIT
LESS THAN 50
SANDS WITH
FINES
SP
(LITTLE OR NO FINES)
ML
SC
SM
NOTE: Multiple symbols are used to indicate borderline or dual soil classifications
MORE THAN 50%
OF COARSE
FRACTION
PASSING NO. 4
SIEVE
CLAYEY GRAVELS, GRAVEL -
SAND - CLAY MIXTURES
CLAYEY SANDS, SAND - CLAY
MIXTURES
INORGANIC SILTS, ROCK
FLOUR, CLAYEY SILTS WITH
SLIGHT PLASTICITY
ORGANIC SILTS AND ORGANIC
SILTY CLAYS OF LOW
PLASTICITY
INORGANIC SILTS, MICACEOUS
OR DIATOMACEOUS SILTY
SOILS
ORGANIC CLAYS AND SILTS OF
MEDIUM TO HIGH PLASTICITY
INORGANIC CLAYS OF HIGH
PLASTICITY
MORE THAN 50%
PASSING NO. 200
SIEVE
MORE THAN 50%
RETAINED ON NO.
200 SIEVE
WELL-GRADED GRAVELS,
GRAVEL - SAND MIXTURES
POORLY-GRADED GRAVELS,GRAVEL - SAND MIXTURES
INORGANIC CLAYS OF LOW TO
MEDIUM PLASTICITY, GRAVELLY
CLAYS, SANDY CLAYS, SILTY
CLAYS, LEAN CLAYS
GRAPH
SYMBOLS
AC
Cement Concrete
Sampler Symbol Descriptions
Groundwater Contact
Material Description Contact
No Visible Sheen
Slight Sheen
Moderate Sheen
Heavy Sheen
Not Tested
Laboratory / Field Tests
Percent fines
Atterberg limits
Chemical analysis
Laboratory compaction test
Consolidation test
Direct shear
Hydrometer analysis
Moisture content
Moisture content and dry density
Organic content
Permeability or hydraulic conductivity
Plasticity index
Pocket penetrometer
Parts per million
Sieve analysis
Triaxial compression
Unconfined compression
Vane shear
2
14
18
18
18
50/5"
5
3
1
5
9 inches asphalt pavement
3 inches crushed rock base course
Brown silty fine to coarse gravel with sand and
cobbles (very dense, moist) (fill)
Gray silt with fine to medium sand and
occasional gravel (soft to medium stiff, moist
to wet)
Dark gray silty fine sand (loose, wet)
%F = 31%
AC
GM
ML
SM
1
2
3
4
5
SA
1.0
3.0
5.0
15.0
16.5
Concrete surface
seal
Bentonite seal
2-inch Schedule 40
PVC well casing
10-20 colorado
silica sand backfill
2-inch Schedule 40
PVC screen,
0.02-inch slot width
31
Logged By
NLTDrilled
Date Measured
Drilling
Method4/6/20134/6/2013
Horizontal
Datum
Vertical Datum
DOE Well I.D.: BHN 225
A 2 (in) well was installed on 4/6/2013 to a depth of 5 (ft).
4/9/2013Easting (X)
Northing (Y)
Drilling
Equipment
16.5
Top of Casing
Elevation (ft)
StartEnd
Checked By
4.7
XL Trailer Mounted Drill Rig
Elevation (ft)
Groundwater
Driller
Depth to
Water (ft)
SMJTotal
Depth (ft)Hollow-Stem Auger
Notes:
Hammer
Data
Surface Elevation (ft)
49.3
54
Rope and Cathead
Geologic Drill
Exploration, Inc.
Flush-mount
monument
Note: See Figure A-1 for explanation of symbols.
FIELD DATA
De
p
t
h
(
f
e
e
t
)
0
5
10
15
In
t
e
r
v
a
l
El
e
v
a
t
i
o
n
(
f
e
e
t
)
50
45
40
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
Re
c
o
v
e
r
e
d
(
i
n
)
Bl
o
w
s
/
f
o
o
t
Gr
a
p
h
i
c
L
o
g
MATERIAL
DESCRIPTION
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
Sa
m
p
l
e
N
a
m
e
Wa
t
e
r
L
e
v
e
l
WELL LOG
Dr
y
D
e
n
s
i
t
y
,
(p
c
f
)
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
,
%
Log of Monitoring Well B-1
30th Street NE Area Flooding Phase 1
Auburn, Washington
0153-040-00
Project:
Project Location:
Project Number:Figure A-2
Sheet 1 of 1Re
d
m
o
n
d
:
D
a
t
e
:
4
/
3
0
/
1
3
P
a
t
h
:
P
:
\
0
\
0
1
5
3
0
4
0
\
0
0
\
G
I
N
T
\
0
1
5
3
0
4
0
0
0
.
G
P
J
D
B
T
e
m
p
l
a
t
e
/
L
i
b
T
e
m
p
l
a
t
e
:
G
E
O
E
N
G
I
N
E
E
R
S
8
.
G
D
T
/
G
E
I
8
_
G
E
O
T
E
C
H
_
W
E
L
L
1
AL
2
3
4
SA
5
6
18
18
12
18
18
18
4
1
7
17
8
13
6 inches asphalt pavement
3 inches crushed rock base course
Gray-brown silt with fine sand (soft, wet)
Non-plastic silt
With thin lenses of silty fine sand
Dark gray sandy silt (stiff to very stiff, wet)
Black fine sand with occasional gravel (loose to
medium dense, wet)
AC
ML
ML
SP
%F = 61%
Gravel at 17.5 feet
39
26
Total
Depth (ft)
Hammer
Data
System
Datum
StartEnd
Checked By
Logged By
NLTDrilled
Notes:
SMJ
Surface Elevation (ft)
Vertical Datum
Driller
Groundwater Depth to
Water (ft)Date Measured Elevation (ft)
Easting (X)
Northing (Y)
XL Trailer Mounted Drill Rig
Geologic Drill
Exploration, Inc.Drilling
Method Hollow-Stem Auger21.5
Rope and Cathead Drilling
Equipment
4/6/20134/6/2013
54
Note: See Figure A-1 for explanation of symbols.
FIELD DATA
De
p
t
h
(
f
e
e
t
)
0
5
10
15
20
In
t
e
r
v
a
l
El
e
v
a
t
i
o
n
(
f
e
e
t
)
50
45
40
35
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Re
c
o
v
e
r
e
d
(
i
n
)
Gr
a
p
h
i
c
L
o
g
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
Bl
o
w
s
/
f
o
o
t
MATERIAL
DESCRIPTION
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
Wa
t
e
r
L
e
v
e
l
Log of Boring B-2
30th Street NE Area Flooding Phase 1
Auburn, Washington
0153-040-00
Project:
Project Location:
Project Number:Figure A-3
Sheet 1 of 1Re
d
m
o
n
d
:
D
a
t
e
:
4
/
3
0
/
1
3
P
a
t
h
:
P
:
\
0
\
0
1
5
3
0
4
0
\
0
0
\
G
I
N
T
\
0
1
5
3
0
4
0
0
0
.
G
P
J
D
B
T
e
m
p
l
a
t
e
/
L
i
b
T
e
m
p
l
a
t
e
:
G
E
O
E
N
G
I
N
E
E
R
S
8
.
G
D
T
/
G
E
I
8
_
G
E
O
T
E
C
H
_
S
T
A
N
D
A
R
D
REMARKS
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
,
%
Dr
y
D
e
n
s
i
t
y
,
(p
c
f
)
1
2
3
4
SA
5
6
7
18
18
18
18
12
11
1
4
17
24
21
7 inches asphalt pavement
3 inches crushed rock base course
Gray silty fine sand with occasional gravel (loose
to medium dense, wet)
Gray silty fine sand to sandy silt (loose soft, wet)
Dark gray silty fine sand (medium dense, wet)
Dark gray fine sand with silt (medium dense, wet)
AC
SM
SM/ML
SM
SP-SM
%F = 43%29
Total
Depth (ft)
Hammer
Data
System
Datum
StartEnd
Checked By
Logged By
NLTDrilled
Notes:
SMJ
Surface Elevation (ft)
Vertical Datum
Driller
Groundwater Depth to
Water (ft)Date Measured Elevation (ft)
Easting (X)
Northing (Y)
XL Trailer Mounted Drill Rig
Geologic Drill
Exploration, Inc.Drilling
Method Hollow-Stem Auger21.5
Rope and Cathead Drilling
Equipment
4/6/20134/6/2013
56
Note: See Figure A-1 for explanation of symbols.
FIELD DATA
De
p
t
h
(
f
e
e
t
)
0
5
10
15
20
In
t
e
r
v
a
l
El
e
v
a
t
i
o
n
(
f
e
e
t
)
55
50
45
40
35
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Re
c
o
v
e
r
e
d
(
i
n
)
Gr
a
p
h
i
c
L
o
g
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
Bl
o
w
s
/
f
o
o
t
MATERIAL
DESCRIPTION
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
Wa
t
e
r
L
e
v
e
l
Log of Boring B-3
30th Street NE Area Flooding Phase 1
Auburn, Washington
0153-040-00
Project:
Project Location:
Project Number:Figure A-4
Sheet 1 of 1Re
d
m
o
n
d
:
D
a
t
e
:
4
/
3
0
/
1
3
P
a
t
h
:
P
:
\
0
\
0
1
5
3
0
4
0
\
0
0
\
G
I
N
T
\
0
1
5
3
0
4
0
0
0
.
G
P
J
D
B
T
e
m
p
l
a
t
e
/
L
i
b
T
e
m
p
l
a
t
e
:
G
E
O
E
N
G
I
N
E
E
R
S
8
.
G
D
T
/
G
E
I
8
_
G
E
O
T
E
C
H
_
S
T
A
N
D
A
R
D
REMARKS
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
,
%
Dr
y
D
e
n
s
i
t
y
,
(p
c
f
)
1
2
3
4
SA
5
18
8
13
18
0
4
27
40
21
21
3 inches sod
Brown silty fine sand (very loose to loose, moist
to wet)
Brown silty fine to coarse gravel with sand
(medium dense, wet)
Black fine to coarse sand with gravel to fine to
coarse gravel with sand (medium dense to
dense, wet)
Dark gray fine to medium sand with gravel
(medium dense, wet)
SOD
SM
GM
SW-GW
SP
%F = 4%18
Total
Depth (ft)
Hammer
Data
System
Datum
StartEnd
Checked By
Logged By
NLTDrilled
Notes:
SMJ
Surface Elevation (ft)
Vertical Datum
Driller
Groundwater Depth to
Water (ft)Date Measured Elevation (ft)
Easting (X)
Northing (Y)
XL Trailer Mounted Drill Rig
Geologic Drill
Exploration, Inc.Drilling
Method Hollow-Stem Auger21.5
Rope and Cathead Drilling
Equipment
4/6/20134/6/2013
58
Note: See Figure A-1 for explanation of symbols.
FIELD DATA
De
p
t
h
(
f
e
e
t
)
0
5
10
15
20
In
t
e
r
v
a
l
El
e
v
a
t
i
o
n
(
f
e
e
t
)
55
50
45
40
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Re
c
o
v
e
r
e
d
(
i
n
)
Gr
a
p
h
i
c
L
o
g
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
Bl
o
w
s
/
f
o
o
t
MATERIAL
DESCRIPTION
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
Wa
t
e
r
L
e
v
e
l
Log of Boring B-4
30th Street NE Area Flooding Phase 1
Auburn, Washington
0153-040-00
Project:
Project Location:
Project Number:Figure A-5
Sheet 1 of 1Re
d
m
o
n
d
:
D
a
t
e
:
4
/
3
0
/
1
3
P
a
t
h
:
P
:
\
0
\
0
1
5
3
0
4
0
\
0
0
\
G
I
N
T
\
0
1
5
3
0
4
0
0
0
.
G
P
J
D
B
T
e
m
p
l
a
t
e
/
L
i
b
T
e
m
p
l
a
t
e
:
G
E
O
E
N
G
I
N
E
E
R
S
8
.
G
D
T
/
G
E
I
8
_
G
E
O
T
E
C
H
_
S
T
A
N
D
A
R
D
REMARKS
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
,
%
Dr
y
D
e
n
s
i
t
y
,
(p
c
f
)
18
7
8
0
18
18
2
19
13
21
21
23
3 inches sod
Brown silt with fine sand (soft, wet)
Non-plastic silt
Dark gray fine to medium sand with silt and
occasional gravel (medium dense, wet)
Black gravelly fine to coarse sand (medium
dense, wet)
%F = 4%
Gray fine to medium sand with silt and gravel
(medium dense, wet)
Dark gray fine to medium sand with gravel
(medium dense, wet)
SOD
ML
SP-SM
SW
SP-SM
SP
1
AL
2
3
SA
4
5
6
1.0
8.0
10.0
25.0
26.5
Concrete surface
seal
Bentonite seal
2-inch Schedule 40
PVC well casing
10-20 colorado
silica sand backfill
2-inch Schedule 40
PVC screen,
0.02-inch slot width
38
14
Logged By
NLTDrilled
Date Measured
Drilling
Method4/6/20134/6/2013
Horizontal
Datum
Vertical Datum
DOE Well I.D.: BHN 396
A 2 (in) well was installed on 4/6/2013 to a depth of 10
(ft).
4/9/2013Easting (X)
Northing (Y)
Drilling
Equipment
26.5
Top of Casing
Elevation (ft)
StartEnd
Checked By
6.0
XL Trailer Mounted Drill Rig
Elevation (ft)
Groundwater
Driller
Depth to
Water (ft)
SMJTotal
Depth (ft)Hollow-Stem Auger
Notes:
Hammer
Data
Surface Elevation (ft)
51.0
57
Rope and Cathead
Geologic Drill
Exploration, Inc.
Flush-mount
monument
Note: See Figure A-1 for explanation of symbols.
FIELD DATA
De
p
t
h
(
f
e
e
t
)
0
5
10
15
20
25
In
t
e
r
v
a
l
El
e
v
a
t
i
o
n
(
f
e
e
t
)
55
50
45
40
35
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
Re
c
o
v
e
r
e
d
(
i
n
)
Bl
o
w
s
/
f
o
o
t
Gr
a
p
h
i
c
L
o
g
MATERIAL
DESCRIPTION
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Wa
t
e
r
L
e
v
e
l
WELL LOG
Dr
y
D
e
n
s
i
t
y
,
(p
c
f
)
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
,
%
Log of Monitoring Well B-5
30th Street NE Area Flooding Phase 1
Auburn, Washington
0153-040-00
Project:
Project Location:
Project Number:Figure A-6
Sheet 1 of 1Re
d
m
o
n
d
:
D
a
t
e
:
4
/
3
0
/
1
3
P
a
t
h
:
P
:
\
0
\
0
1
5
3
0
4
0
\
0
0
\
G
I
N
T
\
0
1
5
3
0
4
0
0
0
.
G
P
J
D
B
T
e
m
p
l
a
t
e
/
L
i
b
T
e
m
p
l
a
t
e
:
G
E
O
E
N
G
I
N
E
E
R
S
8
.
G
D
T
/
G
E
I
8
_
G
E
O
T
E
C
H
_
W
E
L
L
FI
G
U
R
E
A
-
7
SI
E
V
E
A
N
A
L
Y
S
I
S
R
E
S
U
L
T
S
EXPLORATION
NUMBER
DEPTH
(ft) SOIL CLASSIFICATION
B-1
B-2
B-3
B-4
15
12½
15
17½
Dark gray silty fine sand (SM)
Dark gray sandy silt (ML)
Dark gray silty fine sand (SM)
Dark gray fine to medium sand with gravel (SP)
0153-040-00 SAS: SAS 04-11-2013
SYMBOL
3/8” 3” #20 #200 #40 #60 #100 1.5” #10 #4 3/4”
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10 100 1000
PE
R
C
E
N
T
P
A
S
S
I
N
G
B
Y
W
E
I
G
H
T
.
GRAIN SIZE IN MILLIMETERS
U.S. STANDARD SIEVE SIZE
SAND SILT OR CLAY COBBLES GRAVEL
COARSE MEDIUM FINE COARSE FINE BOULDERS
FI
G
U
R
E
A
-
8
SI
E
V
E
A
N
A
L
Y
S
I
S
R
E
S
U
L
T
S
EXPLORATION
NUMBER
DEPTH
(ft) SOIL CLASSIFICATION
B-5 15 Black gravelly fine to course sand (SW)
0153-040-00 SAS: SAS 04-11-2013
SYMBOL
3/8” 3” #20 #200 #40 #60 #100 1.5” #10 #4 3/4”
0
10
20
30
40
50
60
70
80
90
100
0.001 0.01 0.1 1 10 100 1000
PE
R
C
E
N
T
P
A
S
S
I
N
G
B
Y
W
E
I
G
H
T
.
GRAIN SIZE IN MILLIMETERS
U.S. STANDARD SIEVE SIZE
SAND SILT OR CLAY COBBLES GRAVEL
COARSE MEDIUM FINE COARSE FINE BOULDERS
APPENDIX B
Previous Studies
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
February 13, 2014 | Page B-1
File No. 0153-040-00
APPENDIX B
PREVIOUS STUDIES
This appendix includes:
■ The log of one boring completed by GeoEngineers, Inc. in 1996 for the pump station.
■ The logs of two borings completed by Earth Consultants in 1990 for a development north of
30th Street NE.
■ The logs of two test pits completed by Earth Consultants in 1997 for a development south of
30th Street NE and west of the Airport.
APPENDIX C
Report Limitations and Guidelines for Use
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
February 13, 2014 | Page C-1
File No. 0153-040-00
APPENDIX C
REPORT LIMITATIONS AND GUIDELINES FOR USE1
This appendix provides information to help you manage your risks with respect to the use of
this report.
Geotechnical Services Are Performed For Specific Purposes, Persons and Projects
This report has been prepared for the exclusive use of City of Auburn, Otak, Inc., and their
authorized agents. This report is not intended for use by others, and the information contained
herein is not applicable to other sites.
GeoEngineers structures our services to meet the specific needs of our clients. For example, a
geotechnical or geologic study conducted for a civil engineer or architect may not fulfill the needs
of a construction contractor or even another civil engineer or architect that are involved in the
same project. Because each geotechnical or geologic study is unique, each geotechnical
engineering or geologic report is unique, prepared solely for the specific client and project site.
Our report is prepared for the exclusive use of our Client. No other party may rely on the product of
our services unless we agree in advance to such reliance in writing. This is to provide our firm with
reasonable protection against open-ended liability claims by third parties with whom there would
otherwise be no contractual limits to their actions. Within the limitations of scope, schedule and
budget, our services have been executed in accordance with our Agreement with the Client and
generally accepted geotechnical practices in this area at the time this report was prepared.
This report should not be applied for any purpose or project except the one originally contemplated.
A Geotechnical Engineering Or Geologic Report Is Based On A Unique Set Of
Project-Specific Factors
This report has been prepared for the City of Auburn 30th Street NE Area Flooding, Phase 1 project
in Auburn, Washington. GeoEngineers considered a number of unique, project-specific factors
when establishing the scope of services for this project and report. Unless GeoEngineers
specifically indicates otherwise, do not rely on this report if it was:
■ not prepared for you,
■ not prepared for your project,
■ not prepared for the specific site explored, or
■ completed before important project changes were made.
For example, changes that can affect the applicability of this report include those that affect:
■ the function of the proposed structure;
■ elevation, configuration, location, orientation or weight of the proposed structure;
■ composition of the design team; or
■ project ownership.
1 Developed based on material provided by ASFE, Professional Firms Practicing in the Geosciences; www.asfe.org .
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
Page C-2 | February 13, 2014 | GeoEngineers, Inc.
File No. 0153-040-00
If important changes are made after the date of this report, GeoEngineers should be given the
opportunity to review our interpretations and recommendations and provide written modifications
or confirmation, as appropriate.
Subsurface Conditions Can Change
This geotechnical or geologic report is based on conditions that existed at the time the study was
performed. The findings and conclusions of this report may be affected by the passage of time, by
manmade events such as construction on or adjacent to the site, or by natural events such as
floods, earthquakes, slope instability or groundwater fluctuations. Always contact GeoEngineers
before applying a report to determine if it remains applicable.
Most Geotechnical and Geologic Findings Are Professional Opinions
Our interpretations of subsurface conditions are based on field observations from widely spaced
sampling locations at the site. Site exploration identifies subsurface conditions only at those
points where subsurface tests are conducted or samples are taken. GeoEngineers reviewed field
and laboratory data and then applied our professional judgment to render an opinion about
subsurface conditions throughout the site. Actual subsurface conditions may differ, sometimes
significantly, from those indicated in this report. Our report, conclusions and interpretations should
not be construed as a warranty of the subsurface conditions.
Geotechnical Engineering Report Recommendations Are Not Final
Do not over-rely on the preliminary construction recommendations included in this report. These
recommendations are not final, because they were developed principally from GeoEngineers’
professional judgment and opinion. GeoEngineers’ recommendations can be finalized only by
observing actual subsurface conditions revealed during construction. GeoEngineers cannot
assume responsibility or liability for this report's recommendations if we do not perform
construction observation.
Sufficient monitoring, testing and consultation by GeoEngineers should be provided during
construction to confirm that the conditions encountered are consistent with those indicated by the
explorations, to provide recommendations for design changes should the conditions revealed
during the work differ from those anticipated, and to evaluate whether or not earthwork activities
are completed in accordance with our recommendations. Retaining GeoEngineers for construction
observation for this project is the most effective method of managing the risks associated with
unanticipated conditions.
A Geotechnical Engineering or Geologic Report Could Be Subject To Misinterpretation
Misinterpretation of this report by other design team members can result in costly problems. You
could lower that risk by having GeoEngineers confer with appropriate members of the design team
after submitting the report. Also retain GeoEngineers to review pertinent elements of the design
team's plans and specifications. Contractors can also misinterpret a geotechnical engineering or
geologic report. Reduce that risk by having GeoEngineers participate in pre-bid and
preconstruction conferences, and by providing construction observation.
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
February 13, 2014 | Page C-3
File No. 0153-040-00
Do Not Redraw the Exploration Logs
Geotechnical engineers and geologists prepare final boring and testing logs based upon their
interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in
a geotechnical engineering or geologic report should never be redrawn for inclusion in architectural
or other design drawings. Only photographic or electronic reproduction is acceptable, but
recognize that separating logs from the report can elevate risk.
Give Contractors a Complete Report and Guidance
Some owners and design professionals believe they can make cont ractors liable for unanticipated
subsurface conditions by limiting what they provide for bid preparation. To help prevent costly
problems, give contractors the complete geotechnical engineering or geologic report, but preface it
with a clearly written letter of transmittal. In that letter, advise contractors that the report was not
prepared for purposes of bid development and that the report's accuracy is limited; encourage
them to confer with GeoEngineers and/or to conduct additional study to obtain the specific types of
information they need or prefer. A pre-bid conference can also be valuable. Be sure contractors
have sufficient time to perform additional study. Only then might an owner be in a position to give
contractors the best information available, while requiring them to at least share the financial
responsibilities stemming from unanticipated conditions. Further, a contingency for unanticipated
conditions should be included in your project budget and schedule.
Contractors Are Responsible For Site Safety on Their Own Construction Projects
Our geotechnical recommendations are not intended to direct the contractor’s procedures,
methods, schedule or management of the work site. The contractor is solely responsible for job
site safety and for managing construction operations to minimize risks to on-site personnel and to
adjacent properties.
Read These Provisions Closely
Some clients, design professionals and contractors may not recognize that the geoscience
practices (geotechnical engineering or geology) are far less exact than other engineering and
natural science disciplines. This lack of understanding can create unrealistic expectations that
could lead to disappointments, claims and disputes. GeoEngineers includes these explanatory
“limitations” provisions in our reports to help reduce such risks. Please confer with GeoEngineers
if you are unclear how these “Report Limitations and Guidelines for Use” apply to your project
or site.
Geotechnical, Geologic and Environmental Reports Should Not Be Interchanged
The equipment, techniques and personnel used to perform an environmental study differ
significantly from those used to perform a geotechnical or geologic study and vice versa. For that
reason, a geotechnical engineering or geologic report does not usually relate any environmental
findings, conclusions or recommendations; e.g., about the likelihood of encountering underground
storage tanks or regulated contaminants. Similarly, environmental reports are not used to address
geotechnical or geologic concerns regarding a specific project.
30TH STREET NE AREA FLOODING, PHASE 1 Auburn, Washington
Page C-4 | February 13, 2014 | GeoEngineers, Inc.
File No. 0153-040-00
Biological Pollutants
GeoEngineers’ Scope of Work specifically excludes the investigation, detection, prevention or
assessment of the presence of Biological Pollutants. Accordingly, this report does not include any
interpretations, recommendations, findings, or conclusions regarding the detecting, assessing,
preventing or abating of Biological Pollutants and no conclusions or inferences should be drawn
regarding Biological Pollutants, as they may relate to this project. The term “Biological Pollutants”
includes, but is not limited to, molds, fungi, spores, bacteria, and viruses, and/or any of their
byproducts.
Earth Science + Technology
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for
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