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DRAFT GEOTECHNICAL REPORT (60% DESIGN)
CEDAR RIVER HATCHERY
BCF REPLACEMENT PROJECT
SEATTLE, WASHINGTON
Work Authorization No.: C114068
June 2019
707 South Plummer Street
Seattle, Washington 98134
TABLE OF CONTENTS
Page
1.0 INTRODUCTION .....................................................................................................1
2.0 PURPOSE AND SCOPE OF WORK .........................................................................1
3.0 PROJECT UNDERSTANDING ................................................................................1
3.1 SITE DESCRIPTION ...........................................................................................1
3.2 PROJECT DESCRIPTION ....................................................................................2
4.0 SUBSURFACE CONDITIONS .................................................................................2
4.1 GENERAL GEOLOGY ........................................................................................3
4.2 SOIL CONDITIONS............................................................................................3
4.3 GROUNDWATER CONDITIONS ..........................................................................4
5.0 SEISMIC CONSIDERATIONS ................................................................................4
5.1 SEISMIC SETTING ............................................................................................4
5.2 SEISMIC BASIS OF DESIGN ...............................................................................5
5.3 SEISMIC DESIGN PARAMETERS ........................................................................5
5.4 SEISMICALLY INDUCED GEOTECHNICAL HAZARDS .........................................5
5.4.1 Surface Fault Rupture .....................................................................6
5.4.2 Liquefaction Potential and Liquefaction Related Hazards .............6
6.0 PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS .........................6
6.1 CONCRETE SILL AND EQUIPMENT VAULT DESIGN ..........................................7
6.1.1 Bearing Capacity and Settlement ....................................................7
6.1.2 Concrete Sill Lateral Resistance .....................................................7
6.1.3 Lateral Earth Pressures for Equipment Vault Design .....................8
6.1.4 Equipment Vault and Concrete Sill Uplift Resistance ....................8
6.2 CONSTRUCTION CONSIDERATIONS ..................................................................8
6.2.1 Temporary Excavation Support and Dewatering ............................8
6.2.2 Subgrade Preparation ......................................................................11
6.2.3 Pipe Subgrade and Bedding ............................................................11
6.2.4 Backfill and Compaction ................................................................12
6.2.5 Wet Weather Earthwork .................................................................13
6.2.6 Construction Drainage and Erosion Control ...................................13
7.0 LIMITATIONS ..........................................................................................................13
8.0 REFERENCES ...........................................................................................................16
SPU GEOTECHNICAL ENGINEERING
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List of Tables (within text)
Table 1 Seismic Design Parameters
List of Figures (following text)
Figure 1 Site and Exploration Map
Figure 2 Mapped Geologically Hazardous Areas
Figure 3 Generalized Subsurface Profile
Figure 4 Loads for Buried Structure Design
Appendix A: Field Exploration Program
Figure A-1 Key to Symbols and Terms Used on Boring Logs (2 sheets)
Figure A-2 through A-4 Summary Boring Logs B-101 through B-103
Figure A-5 Summary Boring Log B-201
Appendix B: Laboratory Testing Program
Appendix C: Historical Explorations.
DRAFT GEOTECHNICAL REPORT (60% DESIGN)
CEDAR RIVER HATCHERY BCF REPLACEMENT PROJECT
SEATTLE, WASHINGTON
1.0 INTRODUCTION
This report presents the results of our geotechnical investigation and our
recommendations for preliminary design and construction of the Cedar River Hatchery
Broodstock Collection Facility (BCF) Replacement Project (Project) in Renton,
Washington. The Project will include installing a permanent concrete sill across the
Cedar River to support removable hydraulic picket panels and installing a small control
vault for the weir on the south bank of the river. The approximate location of the Project
features is shown on Figure 1.
We have organized this report into several sections. The first three sections describe the
purpose and scope of our work and our understanding of the Project. The remaining
sections present the site subsurface conditions, seismic considerations, and our
geotechnical engineering findings and recommendations.
Tables within the report provide data that are described in the text. Figures illustrating
Project features are presented at the end of the text. Field data are presented in Appendix
A, geotechnical laboratory test results are presented in Appendix B, and logs of relevant
historical explorations are provided in Appendix C.
2.0 PURPOSE AND SCOPE OF WORK
The purpose of our work is to provide the Project Team with subsurface information and
interpretation, and preliminary geotechnical engineering recommendations to support
their design of the Project.
Our scope of work for this Project included:
Assessing subsurface conditions using explorations, laboratory tests, and historical
geotechnical reports and explorations;
Performing geotechnical assessment and analysis;
Providing geotechnical recommendations; and,
Preparing this geotechnical engineering report.
3.0 PROJECT UNDERSTANDING
3.1 SITE DESCRIPTION
The Project site is located within or adjacent to the Cedar River immediately east of
where the river passes under Interstate 405. The parcels along the north and south bank of
the river are owned by the City of Renton. The parcel along the north bank of the river is
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occupied by the Renton Community Center and the Cedar River Park. Other than a boat
ramp, the parcel along the south bank of the river is undeveloped.
At the proposed concrete sill location, the elevation of the streambed is approximately 27
feet. An approximately 12-foot-tall rock wall provides grade separation between the river
and the Renton Community Center property to the north. The ground surface slopes up
gradually from elevation 37 feet at the top of the wall to elevation 40 feet approximately
80 feet to the north. The ground surface south of the river slopes up from the river to
elevation 52 feet at the Cedar River trailhead approximately 120 feet to the south. The
slope generally has an incline of less than 5 percent, with the exception of a 16-foot-tall
slope located approximately 70 feet south of the river that has an average incline of 80
percent.
The Project site is located in a high seismic hazard and adjacent to steep slope
Geologically Hazardous Areas as mapped by the City of Renton. The Renton Municipal
Code (RMC) defines two types of steep slopes, sensitive and protected. Sensitive slopes
are defined as having and incline between 25 and 40 percent, while protected slopes are
defined as having an incline of 40 percent or more and vertical elevation change of at
least 15 feet. Sensitive and protected slopes are mapped approximately 70 feet south of
the river and along the north bank of the river. The RMC defines high seismic hazards as
areas underlain by soft or loose saturated soil. The river and the north and south banks are
mapped as a high seismic hazard area.
The Geologically Hazardous Areas in the vicinity of the Project are shown on Figure 2.
Design and construction recommendations related to the Geologically Hazardous Areas
are discussed in Sections 5.0 and 6.0 of this Report.
3.2 PROJECT DESCRIPTION
We understand that the purpose of the BCF, which has been operated seasonally since
2008, is to capture migrating sockeye salmon for transport to the Cedar River Hatchery.
Currently the entire facility is installed and removed once a year. The proposed facility
will consist of a permanent approximately 20-foot by 68-foot concrete sill in the Cedar
River to support removable structures including a hydraulic picket system, a tip gate, and
a fish trap. The concrete sill will bear on near surface soil. A 12-foot by 8-foot equipment
vault will be installed on the south bank of the river to house controls for the BCF. The
base of the equipment vault will be approximately 6 feet below ground surface (bgs).
4.0 SUBSURFACE CONDITIONS
We based our interpretation of subsurface conditions on published geologic maps,
information obtained from new and historical subsurface explorations, and laboratory
tests on select soil samples. The new explorations included four borings. Figure 1 shows
the location of the new and historical explorations. We prepared a generalized subsurface
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profile through the concrete sill based on our interpretation of the subsurface stratigraphy.
The profile alignment is shown on Figure 1, the profile is shown on Figure 3.
The conclusions and analyses provided in this report are based on subsurface soil
conditions interpreted from these explorations. The nature and extent of variations
between the explorations and current conditions may not become evident until additional
explorations are completed, or construction begins. If variations are encountered, it will
be necessary to reevaluate the conclusions and recommendations in this report.
4.1 GENERAL GEOLOGY
The general geologic condition of the Puget Sound is a result of glacial and non-glacial
activity that occurred over the course of millions of years. Based on our review of the
geologic map of Washington (Washington Geological Survey, 2017), the Project vicinity
is underlain by alluvium and recent fill. During our subsurface exploration program, we
encountered these geologic units as well as sandstone.
4.2 SOIL CONDITIONS
Based on our interpretation of historical and new explorations, the site soil generally
consists of:
Fill
Deposits interpreted to be fill were encountered from the ground surface to a maximum
depth of 15 feet bgs in borings completed north of the river (B-101 and B-201). The fill
generally consists of concrete debris; however, an approximately 1.5-foot-thick layer of
silty sand was encountered 9 feet bgs in boring B-201.
Alluvium
Deposits interpreted to be alluvium were encountered from the ground surface to depths
of between 5 and 11 feet bgs in borings completed south of the river (B-102 and B-103),
and below fill to the maximum depth explored in borings completed north of the river
(B-201). The alluvium generally consists of medium dense to dense silty sand with
varying amounts of gravel, dense to very dense gravel with varying amounts of sand and
silt, and stiff silt with varying amounts of sand and gravel. Standard Penetration Test
blow counts recorded on the B-201 boring log are likely overstated due to the presence of
gravel.
Sandstone
Sandstone was encountered below alluvium to the full depth explored in borings
completed south of the river (B-102 and B-103). In general, the sandstone is highly to
slightly weathered and very weak to slightly weak.
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4.3 GROUNDWATER CONDITIONS
Groundwater levels at the site are likely influenced by the Cedar River. Because it would
be unusual for groundwater levels to be lower than the streambed, we anticipate that at a
minimum the groundwater elevation would be 27 feet. While drilling the borings south of
the river (B-102 and B-103), we encountered groundwater perched on top of the
sandstone between 5 and 8 feet bgs, which corresponds to elevations 30 and 26 feet.
While drilling the boring north of the river, (B-201), we encountered groundwater within
the alluvium approximately 17 feet bgs, which corresponds to elevation 21 feet. Because
groundwater measurements taken at time of drilling are not always accurate, we
recommend a design groundwater elevation of 30 feet based on expected groundwater
behavior.
5.0 SEISMIC CONSIDERATIONS
The site is located in a seismically active area. In this section, we discuss the seismic
setting at the Project site, provide seismic design parameters, and discuss earthquake-
induced geotechnical hazards at the site including fault rupture, liquefaction, post-
liquefaction vertical settlement, and lateral spreading.
5.1 SEISMIC SETTING
The seismicity of Puget Sound is dominated by the Cascadia Subduction Zone (CSZ) in
which the offshore Juan de Fuca plate subducts beneath the continental North American
plate. Three main types of earthquakes are typically associated with subduction zone
environments: crustal, intraplate, and interplate.
Seismic records in the Puget Sound area clearly indicate the existence of a distinct
shallow zone of crustal seismicity that may have surficial expressions and can extend to
depths of 25 to 30 kilometers (km). Several minor earthquakes occur in the area each
year, most of which are not even felt. However, some of the shallow faults are capable of
producing significant, damaging earthquakes. Perhaps the most notable of these faults are
the Seattle Fault Zone (SFZ) and the South Whidbey Island Fault Zone (SWIFZ).
Research indicates that both the SFZ and the SWIFZ are capable of producing an
earthquake with a magnitude 7.0 or higher which, given the shallow depth and proximity
to the Seattle urban area, could produce intense shaking at the Project site. The Project
site is located 5 km south of the SFZ and 26 km south of the SWIFZ.
A deeper zone of seismicity is associated with the subducting Juan de Fuca plate and
produces intraplate earthquakes at depths of 40 to 70 km beneath the Puget Sound region
(e.g., the 1949 Western Washington magnitude 7.1, 1964 Olympia magnitude 6.7, and
2001 Nisqually magnitude 6.8 earthquakes) and interplate earthquakes at shallow depths
near the Washington coast (e.g., the 1700 Cascadia earthquake with an approximate
magnitude of 9.0).
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5.2 SEISMIC BASIS OF DESIGN
The 2018 International Building Code (IBC) requires that structures be designed for
inertial forces induced by earthquake motions in accordance with ASCE 7. The basis of
design for the ASCE 7 is two-thirds of the Risk-Targeted Maximum Considered
Earthquake (MCER). The MCER is based on a uniform hazard ground motion with 2
percent probability of exceedance in 50 years that has been adjusted to a risk targeted
ground motion representing a 1 percent probability of collapse in 50 years. The ASCE 7
event is referred to as the Design Event (DE).
5.3 SEISMIC DESIGN PARAMETERS
Characterization of the soil profile type is required to determine the site class definition.
Based on standard penetration test (SPT) data collected from our explorations and
historical explorations we determined the site soils are generally Site Class C. The soil
site class is based on a weighted average of the blow counts observed to a depth of 100
feet bgs. The explorations that we reviewed for this Project terminated less than 100 feet
bgs; therefore, we assumed the material density below the deepest sample is the same as
that of the deepest sample for our determination of the site class.
We used a web interface developed by the California Office of Statewide Health
Planning and Development (OSHPD) and the Structural Engineers Association of
California (SEAOC) to determine the mapped spectral accelerations for Site Class B sites
and the site coefficients corresponding to Site Class C. The MCER spectral response
accelerations are obtained by applying the site coefficients to the mapped spectral
accelerations. Finally, the DE spectral response accelerations are obtained by reducing
the MCER spectral accelerations by a factor of 2/3.
The seismic design parameters for the Project are provided in Table 1.
Table 1—Seismic Design Parameters
Site
Class
Mapped Spectral
Accelerations, (g)
Site Coefficients MCER Response
Accelerations, (g)
DE Response
Accelerations, (g)
PGA SS S1 FPGA Fa Fv PGAm SMS SM1 PGA SDS SD1
C 0.61 1.43 0.49 1.20 1.20 1.50 0.73 1.72 0.73 0.49 1.14 0.49
5.4 SEISMICALLY INDUCED GEOTECHNICAL HAZARDS
Potential seismically induced geotechnical hazards may include surface fault rupture,
liquefaction, and lateral spreading. Our review of these hazards is based on the soils
encountered in our explorations and indicated in historical explorations, regional
experience, and our knowledge of local seismicity.
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5.4.1 Surface Fault Rupture
The Project site is located 5 km south of the nearest mapped splay of the SFZ. Although
there is some potential for surface rupture at the site; in our opinion, the risk is low and
special design considerations for surface fault rupture are not warranted for this Project.
5.4.2 Liquefaction Potential and Liquefaction Related Hazards
As part of our seismic analysis, we analyzed the potential of the soil at the Project site to
liquefy. Liquefaction is a momentary loss of some portion of soil shear strength during a
seismic event. The loss of shear strength can potentially cause settlement of the ground
surface, lateral spreading, or landslides.
The site is mapped by the City of Renton as a high seismic hazard area due to the
anticipated presence of soft or loose saturated soil that is susceptible to liquefaction. SPT
blow counts recorded in the new and historical explorations generally indicate that site
soil below the groundwater table is dense to very dense and is therefore not susceptible to
liquefaction. However, we anticipate that the gravel, cobbles, and boulders encountered
in the explorations, have caused observed blow counts and assumed soil density to be
overstated.
Alluvial deposits, like those encountered at the site, generally consist of interbedded
layers of loose to dense or soft to stiff sand, silt, gravel, and cobbles deposited by streams
and running water. This depositional sequence typically results in a soil profile that is
moderately to highly susceptible to liquefaction. As a result, despite the blow counts
observed at the site, we anticipate that liquefaction could occur in portions of the soil
units below the water table. However, we anticipate that the risk of liquefaction related
hazards such as post-seismic settlement and lateral spreading is low. In addition, there is
low risk to human life if the proposed structures fail. As a result, in our opinion, special
design considerations for liquefaction and liquefaction related hazards are not warranted
for the Project.
6.0 PRELIMINARY CONCLUSIONS AND RECOMMENDATIONS
This section presents geotechnical engineering recommendations for design and
construction of the proposed Project features. This includes recommendations for the
geotechnical engineering aspects of:
Concrete Sill and Equipment Vault Design; and
Construction Considerations.
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6.1 CONCRETE SILL AND EQUIPMENT VAULT DESIGN
6.1.1 Bearing Capacity and Settlement
We anticipate that the concrete sill will bear on alluvium and that the equipment vault
will bear on alluvium or sandstone. In general, the anticipated subgrade should provide
suitable support for the proposed structures. However, because soils are variable,
unsuitable subgrade conditions may be encountered at the proposed bearing elevations. If
unsuitable subgrade conditions are encountered at the time of construction, the subgrade
should be evaluated, and the course of action determined by the Geotechnical Engineer-
of-Record.
We recommend static allowable bearing pressures of 2,500 pounds per square foot (psf)
and 4,000 psf for structures bearing on alluvium and sandstone, respectively. The
recommended maximum allowable bearing pressure may be increased by 1/3 for short
term transient conditions such as wind and seismic loading.
We understand that the concrete sill will have a bearing pressure of up to 250 psf. For this
maximum load we estimate that total static settlement will not exceed 0.25 inches. In
general, we estimate that total static settlement of the equipment vault will be less than
0.5 inches. We can provide updated settlement estimates once the foundation loads are
known for this structure. It is anticipated that static settlement of the sill and vault will
occur during construction as loads are applied. Differential static settlement is expected
to be about one-half of the total settlement.
6.1.2 Concrete Sill Lateral Resistance
Lateral forces on the concrete sill will be resisted by a combination of sliding resistance
between the sill and the underlying soil, and soil resistance against the below-grade
portions of the sill. We recommend an allowable coefficient of friction of 0.30 for the
interface between the sill and well compacted native soil. An allowable passive
equivalent fluid unit weight of 136 pounds per cubic foot (pcf) may be assumed for soils
adjacent to the below-grade elements. The passive resistance is mobilized incrementally
as the sill moves laterally and is pushed into the adjacent soil. The full passive resistance
is not estimated to occur until the sill moves a distance into the soil equal to 0.05 times
the depth of the below grade portion of the sill. As a result, approximately 3 inches of
lateral movement are required to mobilize the full passive resistance for the anticipated 5-
foot-deep key walls. If this amount of movement is unacceptable, we recommend using
an allowable at-rest equivalent fluid unit weight of 16 pcf for the soils adjacent to the
below-grade elements. The upper 1-foot of passive or at-rest resistance should be
neglected in the design to account for disturbance, unless it can be determined that
disturbance is unlikely. These allowable values include a factor of safety of 1.5.
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6.1.3 Lateral Earth Pressures for Equipment Vault Design
The proposed equipment vault should be designed to resist lateral loads from the retained
soil and other related surcharge loads. A lateral earth pressure diagram for design of
buried structures is provided on Figure 4. We provide at-rest earth pressures because we
anticipate that the walls of the relatively rigid structure will not be free to rotate. Lateral
loads due to surficial surcharge loading (adjacent footings, fill, traffic, etc.) should be
considered by the designer on a case-by-case basis and should be added to the lateral
earth pressures provided on Figure 4.
6.1.4 Equipment Vault and Concrete Sill Uplift Resistance
Buried structures like the equipment vault that are watertight and that are at least partially
below the groundwater table are subjected to permanent hydrostatic uplift pressures. The
buoyant force on the bottom of these structures is resisted primarily by the weight of the
structure and any soil above the structure. We recommend neglecting the frictional
resistance between the structure walls and the adjacent soil. The uplift pressure on the
base of the equipment vault can be calculated using the formula provided on Figure 4.
We recommend assuming the groundwater table is at the ground surface when calculating
the uplift pressure. The buoyant force is resisted primarily by the weight of the structure
and any soil above the structure. We recommend minimum factors of safety against static
and seismic uplift of 1.2 and 1.0, respectively.
We understand that when the picket weir is raised that the water level on the upstream
side of the sill will be higher than the water level on the downstream side. The sill should
be designed to resist the resulting hydrostatic uplift pressure.
6.2 CONSTRUCTION CONSIDERATIONS
6.2.1 Temporary Excavation Support and Dewatering
Because the Project is in the preliminary design stage and the location and depth of the
proposed features have not been finalized, we have assumed that excavation depths will
be:
Between 1 and 8 feet bgs for the equipment vault and utility trenches on the south
side of the river; and
Between 1 and 6 feet bgs for the concrete sill in the river.
If needed, we can refine our recommendations as the Project design progresses and
excavation depths are determined.
Based on our interpretation of subsurface conditions at the site, and the assumed
excavation depths, it appears that excavations on the south side of the river will be made
in alluvium and possibly sandstone and that excavations within the river will be made in
alluvium. Cobbles and boulders should be anticipated within the alluvium. In general, we
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anticipate that site soil can be excavated using standard excavation equipment and that
the relatively weak near surface sandstone can be excavated using various methods
including an excavator equipped with a hydraulic breaker. The contractor should be
responsible for determining equipment suitability for excavation of the varying soils
noted in this report, as well as for other soil strata, which may be encountered.
The design parameters and the means and methods of supporting and dewatering
temporary excavations are typically the contractor’s responsibility. However, we provide
recommendations for feasible excavation support, and dewatering methods to aid in
planning and design.
Excavation Support Methods
Trench boxes are a passive excavation support system that allow the sides of the
excavation to slough while providing protection for workers in the excavation. Trench
boxes should only be used in areas where structures or steep slopes are not present within
the zone of influence of the excavation and groundwater can be controlled using sumps
and pumps. The zone of influence is defined graphically in Figure A.
If structures, utilities, or steep slopes will be located within the zone of influence of the
trench, and if the anticipated ground movement at the location of these features is
unacceptable, the Project plans and specifications should require shoring systems that
restrict the movement of the sides of the excavation. Feasible shoring systems for the site
that restrict movement of the excavation sides include slide rail and soldier pile and
lagging. If needed, these shoring systems should be designed for the specific situation by
a registered professional engineer.
Based on our understanding of subsurface conditions and the assumed excavation depth
for the equipment vault and utility trenches, we anticipate that, groundwater will be
located less than 3 feet above the base of excavation and that, settlement sensitive
structures, utilities, or steep slopes will not be located within the zone of influence of the
Figure A - Zone of Influence for Temporary Excavations
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excavation. As a result, in our opinion, trench boxes may be suitable for these
excavations as long as the water table can be maintained below the base of excavation.
We anticipate that excavations for the concrete sill will be sloped, however, a shoring
system that restricts movement of the sides of the excavation is required for excavations
where the base of the rock wall, which is mapped as a sensitive slope, is within the zone
of influence. The surcharge from the rock wall should be considered when designing the
shoring.
Temporary Slopes
If the contractor chooses to slope rather than shore excavation sidewalls, the specific
design parameters for temporary slopes should be developed by the contractor’s
competent person in accordance with WAC Chapter 296-155. However, for planning
purposes, a 1.5H:1V inclination can be assumed for temporary sloped excavations in the
site soils.
With time and the presence of seepage and/or precipitation, the stability of temporary
cuts can be significantly reduced. Therefore, construction should proceed as rapidly as
feasible to limit the time the excavations are left open, and runoff water should be
prevented from entering excavations. Heavy construction equipment, building materials,
and surcharge loads such as excavated or imported soil should not be allowed within one
third of the slope height from the top of any excavation.
Dewatering
We anticipate that dewatering will be required to maintain groundwater a minimum of
2 feet below the excavation depth during construction of the site features. Typically,
sumps and pumps are sufficient for dewatering when excavations are less than 3 feet
beneath the water table, excavation faces are supported or sloped appropriately, or if
work can be completed in the wet. If conditions and construction methods do not allow
for open sumps, a well point system may be a viable alternative.
The contractor should choose a method based on the available information and their
selected construction techniques. Well points and other external dewatering systems
should be designed by a qualified professional engineer or geologist. The dewatering plan
should be submitted to SPU Geotechnical Engineering for approval.
Lowering the groundwater table increases the effective stress in the soil which can lead to
settlement at the ground surface, particularly in compressible soils. As a result, the
groundwater table should be drawn down no more than necessary for the proposed work
to avoid damage to adjacent utilities and structures. Based on the soil and groundwater
conditions observed in the new and historical explorations, we anticipate that the
potential for dewatering related settlement is low.
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6.2.2 Subgrade Preparation
Subgrade preparation for the concrete sill, equipment vault, and utilities should begin
with the removal (stripping) of all deleterious matter, asphalt, and concrete. A smooth-
bladed excavator bucket should be used to excavate to the subgrade elevation and foot
traffic on the subgrade should be minimized to reduce the amount of disturbance to the
subgrade. A layer of mineral aggregate or structural concrete may be used to protect the
subgrade once it is exposed.
The exposed subgrade should be observed by the Geotechnical Engineer-of-Record to
evaluate the adequacy of the bearing stratum and to confirm that subsurface conditions
are suitable for the recommended design bearing values. For the anticipated smaller areas
where access is restricted, the subgrade should be evaluated by probing the soil with a
steel rod.
Soft/loose soils identified during subgrade preparation should be compacted to a firm and
unyielding condition or stabilized. Typical subgrade stabilization measures include: over
excavation and replacement with up to one foot of structural fill if the subgrade is not
saturated or 6 inches to one foot of quarry spalls if the subgrade is saturated.
Geosynthetic fabric can also be used to minimize the required thickness of imported fill.
The depth of over excavation, if required, should be determined by the Geotechnical
Engineer-of-Record at the time of construction.
6.2.3 Pipe Subgrade and Bedding
In general, the subgrade soil should provide suitable support for underground utilities,
provided subgrades remain in an undisturbed condition, and the pipes and structures are
bedded as described below. The allowable bearing capacities provided above for the
equipment vault and concrete sill are appropriate for design of the proposed underground
utilities.
Bedding is material placed at the bottom of the trench to provide uniform support along
the bottom of a buried utility. Bedding material and placement procedures should meet
the appropriate requirements and criteria of the 2017 City of Seattle Standard
Specifications for Road Bridge and Municipal Construction (Standard Specifications),
depending on the utility in question. In areas where a trench box is used, the bedding
material should be placed before the trench box is advanced. Bedding material disturbed
by movement of trench boxes should be recompacted prior to final backfilling. Care
should be taken not to disturb the utility as the trench box is advanced.
Trench backfill will be placed on top of the bedding. Refer to the backfill
recommendations provided below.
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6.2.4 Backfill and Compaction
In areas where settlements are to be limited (areas that support slabs, buildings,
pavements, or foundations), excavation backfill shall consist of structural fill meeting the
gradation requirements of Type 17 material in Section 9-03.14, Mineral Aggregate Chart
in the Standard Specifications.
The suitability of excavated site soils for reuse as structural fill depends upon the
gradation and moisture content of the soil when it is placed. As the percentage of fines
(that portion passing the No. 200 sieve) increases, the soil becomes increasingly sensitive
to small changes in moisture content and adequate compaction becomes more difficult to
achieve. Soil containing more than about 5 percent fines cannot be consistently
compacted to a dense non-yielding condition when the water content is greater than about
3 percent above or below optimum. The soil must also be free of organic and other
unsuitable material. In general, the new and historical explorations indicate that the site
soil is generally not suitable for use as structural fill because it has fines contents
substantially greater than 5 percent.
Fill placed in all structural areas and for five feet around such areas, should be compacted
to a minimum of 95 percent of the maximum dry density (MDD) as determined by test
method ASTM D1557. Within a lateral distance of three feet of any retaining wall or
subgrade wall, smaller, possibly hand-held equipment should be used in conjunction with
thinner soil lifts to achieve the required compaction and limit compaction forces on the
wall.
Excavated material not considered suitable for use as structural fill, may be suitable as fill
for unimproved areas that would not be adversely impacted by differential settlement
over time. Common fill material should be onsite or imported material within 3 percent
of the optimum moisture content per ASTM D1557 (Modified Proctor Test) that does not
contain deleterious materials, greater than 5 percent organics, nor material larger than
3-inches in diameter. In general, the new and historical explorations indicate that the site
soil is generally suitable for use as common fill, however, it may require screening to
remove organics. Any proposed imported common fill should be evaluated by the
Geotechnical Engineer-of-Record to determine its suitability. Fill in unimproved areas
should be compacted to a minimum of 90 percent of MDD as determined by test method
ASTM D1557.
The procedure to achieve the specified minimum relative compaction depends on the size
and type of compacting equipment, the number of passes, thickness of the layer being
compacted, and certain soil properties. When the size of the excavation restricts the use
of heavy equipment, smaller equipment can be used, but the soil must be placed in thin
enough lifts to achieve the required compaction. A sufficient number of in-place density
tests should be performed as the fill is placed to verify the required relative compaction is
being achieved.
Cedar River Hatchery BCF Replacement Project
DRAFT Geotechnical Report (60% Design)
June 2019
SPU GEOTECHNICAL ENGINEERING 13
6.2.5 Wet Weather Earthwork
If earthwork is to be performed or fill is to be placed in wet weather or under wet
conditions when control of soil moisture content is not possible, the following
recommendations should apply:
Complete earthwork in small sections to minimize exposure to wet weather;
Place and compact a suitable thickness of clean structural fill immediately
following excavations or the removal of unsuitable soil;
Limit the size of construction equipment if needed to prevent soil disturbance;
Use clean, granular soil for trench backfill with not more than 5 percent by
dry weight passing the U.S. Standard No. 200 sieve. The fines should be non-
plastic;
Slope and seal the ground surface in the construction area with a smooth drum
roller to promote rapid runoff of precipitation, prevent surface water from
flowing into excavations, and to prevent ponding of water;
Protect uncompacted soil so it does not absorb water. Soils that become too
wet for compaction should be removed and replaced with clean granular
materials; and
Excavate and place fill under the full-time observation of a person
experienced in wet weather earthwork to verify that all unsuitable materials
are removed, and suitable compaction and site drainage are achieved.
6.2.6 Construction Drainage and Erosion Control
Surface runoff and erosion at the site can be controlled during construction by careful
grading practices and observance of best management practices (BMPs). Such practices
typically include the construction of shallow, upgrade perimeter ditches or low earthen
berms, and the use of temporary sumps to collect runoff. Erosion during construction can
be minimized by judicious use of erosion control devices. If used, these devices should be
in place and remain in place throughout construction.
Erosion and sedimentation of exposed soils can also be minimized by quickly re-
vegetating exposed areas of soil, and by staging construction such that large areas of the
Project site are not denuded and exposed at the same time. Areas of exposed soil
requiring immediate and/or temporary protection against exposure should be covered
with either mulch or erosion control netting/blankets.
7.0 LIMITATIONS
This report was prepared in accordance with generally accepted professional principles
and practices in the field of geotechnical engineering at the time the report was prepared.
Cedar River Hatchery BCF Replacement Project
DRAFT Geotechnical Report (60% Design)
June 2019
SPU GEOTECHNICAL ENGINEERING 14
The scope of our work did not include environmental assessments or evaluations
regarding the presence or absence of wetlands or hazardous or toxic substances in the
soil, surface water, or groundwater at this site. However, we did not encounter apparent
indications of contamination in our explorations
This geotechnical report is intended to provide information and recommendations to
support preliminary engineering activities for this project. The conclusions and
interpretations presented in this report should not be construed as a warranty of the
subsurface conditions.
Cedar River Hatchery BCF Replacement Project
DRAFT Geotechnical Report (60% Design)
June 2019
SPU GEOTECHNICAL ENGINEERING 15
We appreciate the opportunity to be of service.
Sincerely,
SPU GEOTECHNICAL ENGINEERING
Megan Higgins, P.E.
Senior Geotechnical Engineer
Cedar River Hatchery BCF Replacement Project
DRAFT Geotechnical Report (60% Design)
June 2019
SPU GEOTECHNICAL ENGINEERING 16
8.0 REFERENCES
ASTM International, 2018. American Society of Testing Materials Annual Book of
Standards, Vol. 4.08, West Conshohocken, PA.
City of Seattle, 2017. Standard Specifications for Road Bridge and Municipal
Construction, 2017 Edition.
Seismic Design Maps. Structural Engineers Association of California and California’s
Office of Statewide Health Planning and Development, online application:
https://seismicmaps.org/about.html. Accessed May 2019.
Washington Geological Survey, 2017. Surface Geology, 1:24,000 – GIS Data, September
2017.
Washington Geologic Information Portal. Washington Department of Natural Resources,
Online Geodatabase: https://geologyportal.dnr.wa.gov/. Accessed May 2019.
!.
!.
!.
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B-102
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B-101B
B-101C
B-101D
B-201
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HQ-84-90
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Document Path: P:\MatLab\Secure\GEOTECH\Geotechnical Projects\SPU\Watershed\Cedar River Watershed\(E114068) Cedar BCF\Preliminary Engineering\Field & Lab Work\Site Maps\Broodstock Site Map.mxdLegend
!(SPU BoringHistorical Explorations
!.Boring
#*#*Subsurface Cross Section
Proposed BCF
10 Foot Contours
2 Foot Contours
StreamsClassified
Site & Exploration Map
Cedar River Hatchery
BCF Replacement Project
Renton, Washington
FIGURE 1
April 2019
Project No. C114068
Seattle Public Utilities Geotechnical Engineering
20 0 20 4010
Feet
NAVD88-
I-405Cedar RiverTrail
Ced
a
r
R
i
v
e
r
50
40
40
30
Document Path: P:\MatLab\Secure\GEOTECH\Geotechnical Projects\SPU\Watershed\Cedar River Watershed\(E114068) Cedar BCF\Preliminary Engineering\Field & Lab Work\Site Maps\Broodstock Site Map.mxdLegend
Proposed BCF
10 Foot Contours
Steep Slope Hazard Areas
Sensitive Slope
Protected Slope
Seismic Hazard Areas
High Hazard
Mapped Geologically Hazardous Areas
Cedar River Hatchery
BCF Replacement Project
Renton, Washington
FIGURE 2
Mayl 2019
Project No. C114068
Seattle Public Utilities Geotechnical Engineering
20 0 20 4010
Feet
NAVD88-
APPENDIX A
FIELD EXPLORATION PROGRAM
Cedar River Hatchery BCF Replacement Project
DRAFT Geotechnical Report (60% Design)
June 2019
SPU GEOTECHNICAL ENGINEERING
A-1
APPENDIX A
FIELD EXPLORATION PROGRAM
Subsurface conditions for the current study were explored using hollow stem auger and sonic
core drilling techniques. Three borings, B-101 through B-103, were completed to depths
ranging from 10 inches to 13.25 feet on March 13, 2019, and an additional boring, B-201 was
completed to a depth of 26.5 feet on April 1, 2019. The approximate location of the
explorations is illustrated on Figure 1 in the main body of the text. The explorations were
located relative to prominent features in the area. The approximate ground surface elevations
at the exploration locations were determined based on the topographic survey of the site and
are referenced to the NAVD88 datum.
The borings were drilled by Holocene Drilling, Inc. of Puyallup, Washington, under contract
to SPU Geotechnical Engineering. A track-mounted Diedrich D-50 rig with 4.25-inch inside
diameter (ID) hollow stem augers was used for borings B-101 through B-103, and a track
mounted Geoprobe 8140LC rig with 6.0-inch outside diameter (OD) casing and 4.0-inch ID
core barrel was used for boring B-201. The results of the explorations are summarized on the
individual summary boring logs, which are included here as Figures A-2 through A-5. A key
to the symbols and terms used on the summary logs is presented as Figure A-1.
Soil samples were obtained from all borings at 2.5-foot and 5-foot depth intervals using the
Standard Penetration Test (SPT, ASTM D-1586). The 2.0-inch outside diameter (OD) SPT
sampler was driven into the soil a distance of 18 inches using a 140-pound drive hammer
falling a distance of 30 inches. An automatic hammer was used to operate the hammer and
drive the sampler for both rigs. Recorded blows for each 6 inches of sampler penetration
(blow counts) are shown on the summary logs in this appendix. The blow counts provide a
qualitative measure of the relative density of cohesionless soil, or the relative consistency of
fine-grained soils.
Representative portions of all recovered soil samples were placed in sealed containers and
transported to our laboratory for further observation and testing.
P:\MatLab\Secure\GEOTECH\FORMS\Office\Boring Log Key
SOIL CLASSIFICATION AND
EXPLORATION LOG KEY
FIGURE A-1
(Sheet 1 of 3)Geotechnical Engineering
NOTES:
UNIFIED SOIL CLASSIFICATION SYSTEM - ASTM D2488
LETTER
SYMBOL GROUP NAMEGROUP
SYMBOLMAJOR DIVISION
GRAVEL WITH
BETWEEN 5%
AND 15% FINES
GW-GM
GP-GC
HIGHLY ORGANIC SOILS PT
COARSE
GRAINED
SOILS
CONTAINS
LESS THAN
50% FINES
SAND AND
SANDY SOILS
MORE THAN
50% OF
COARSE
FRACTION
PASSING ON
NO. 4 SIEVE
GRAVEL AND
GRAVELLY
SOILS
MORE THAN
50% OF
COARSE
FRACTION
RETAINED ON
NO. 4 SIEVE
FINE
GRAINED
SOILS
CONTAINS
MORE THAN
50% FINES
SILT
AND
CLAY
TPTOPSOIL
GRAVEL WITH
< 5% FINES
GRAVEL WITH
> 15% FINES
SAND WITH
< 5% FINES
SAND WITH
BETWEEN 5%
AND 15% FINES
SAND WITH
> 15% FINES
LIQUID LIMIT
GREATER
THAN 50
LIQUID LIMIT
LESS THAN 50
GW
MH
SW
SP
SW
GW
CH
OH
GP
GP
GW-GC
GP-GM
GM
GC
SC
CL
OL
SP
SW-SM
SW-SC
SP-SM
SM
SP-SC
ML
CL
ML
Well-graded GRAVEL
Well-graded GRAVEL WITH SAND
Poorly graded GRAVEL
Inorganic SILT, low plasticity
Inorganic SILT WITH SAND, low plasticity
Elastic inorganic SILT, moderate to high plasticity
PEAT soils with high organic contents
TOPSOIL
ORGANIC SILT, low plasticity
Well-graded GRAVEL WITH SILT
Well-graded GRAVEL WITH CLAY
Poorly graded GRAVEL WITH SILT
Well-graded SAND
Well-graded SAND WITH GRAVEL
Poorly graded SAND
Poorly graded SAND WITH GRAVEL
Poorly graded SAND WITH CLAY
Poorly graded GRAVEL WITH SAND
Poorly graded GRAVEL WITH CLAY
Well-graded SAND WITH SILT
Well-graded SAND WITH CLAY
Poorly graded SAND WITH SILT
Lean inorganic CLAY, low plasticity
Lean inorganic CLAY WITH SAND, low plasticity
Fat inorganic CLAY, moderate to high plasticity
SILTY GRAVEL
CLAYEY GRAVEL
SILTY SAND
CLAYEY SAND
ORGANIC SILT or CLAY, moderate to high plasticity
2. Solid lines between soil descriptions indicate change in interpreted geologic unit. Dashed lines indicate
stratigraphic change within the unit.
3. Fines are material passing the U.S. std. #200 sieve.
1. Sample descriptions are based on visual field and laboratory observations using classification methods
of ASTM D2488. Where laboratory data are available, classifications are in accordance with ASTM D2487.
SOIL CLASSIFICATION AND
EXPLORATION LOG KEY
FIGURE A-1
(Sheet 2 of 3)Geotechnical Engineering
P:\MatLab\Secure\GEOTECH\FORMS\Office\Boring Log KeyWELL CONSTRUCTION
Cement Seal Groundwater level
at time of drilling
Measured groundwater
level (date)
Vibrating wire piezometer
measured groundwater
level (date)
Vibrating wire piezometer
Bentonite Seal
Filter Pack
Well Casing
Screened Casing
Slough Soil
Density/consistency, color, USCS group name, minor
constituent; moisture; additional comments.
ORDER OF CLASSIFICATION TERMS
TERM
Laminated
Interbedded
Fractured
Slickensided
Blocky
Lensed
Homogenous
CRITERIA / DESCRIPTION
Alternating layers (< 1/2”) of varying material or color
Alternating layers (> 1/2“) of varying material or color
Breaks easily along definite fracture planes
Polished, glossy, striated fracture planes
Readily breaks into small angular lumps
Inclusions of small pockets of different soil
Same color and appearance throughout
TERM
Parting
Seam
Layer
Pocket
Occasional
Scattered
Numerous
THICKNESS OR SPACING
0 - 1/16” thick
1/16 - 1/2” thick
1/2 - 12” thick
Inclusions < 1” thick
< 1 occurrence per foot
1 > 10 occurrence per foot
> 10 occurrence per foot
TERM
Near Horizontal
Low Angle
High Angle
Near Vertical
CRITERIA
0 - 10 degrees
10 - 45 degrees
45 - 80 degrees
80 - 90 degrees
Slow
Rapid
Water appears slowly on the surface of
the specimen during shaking and does not
disappear or disappears slowly upon squeezing.
Water appears quickly on the surface of
the specimen during shaking and disappears
quickly upon squeezing.
DILATANCY
Slow
Moderate
Rapid
A small amount of water is observed
flowing from the sides of the excavation.
Water collects in the bottom of the excavation
during digging. Some bailing is needed
to observe the excavation bottom.
Water collects in the bottom of the excavation
during digging. Bailing may be ineffective to
observe the excavation bottom.
SEEPAGE
Slight
Moderate
Significant
Soil sloughed from wall
of excavation is < 6” thick.
Soil sloughed from wall of
excavation is between 6” - 12”
thick.
Soil sloughed from wall
of excavation is >12” thick.
CAVING
Very Loose
Loose
Medium Dense
Dense
Very Dense
0 to 4
4 to 10
10 to 30
30 to 50
over 50
0 - 15
15 - 35
35 - 65
65 - 85
85 - 100
> 3
1 - 3
0.3 - 1
0.1 - 0.3
< 0.1
RELATIVE DENSITY OF COARSE-GRAINED COHESIONLESS SOILS
Relative
Density N (blows/ft)
Approximate
Relative Density (lb/ft3)
1/2” Dia. Metal Probe
Penetration Depth (ft)
RELATIVE CONSISTENCY OF FINE-GRAINED COHESIVE SOILS
Very Soft
Soft
Medium Stiff
Stiff
Very Stiff
Hard
0 to 2
2 to 4
4 to 8
8 to 15
15 to 30
over 30
< 250
250 - 500
500 - 1000
1000 - 2000
2000 - 4000
> 4000
> 2
1 - 2
0.5 - 1
0.25 - 0.5
0.1 - 0.25
< 0.1
Relative
Consistency N (blows/ft)
Approximate Undrained
Shear Strength (psf)
1/2” Dia. Metal Probe
Penetration Depth (ft)
Trace
Few
Some
Less than 5%
5 - 15%
15 - 30%
COMPONENT PROPORTIONS
Dry
Moist
Wet
Saturated
Dusty, or dry to the touch.
No visible water. Near optimum moisture content.
Visible free water.
Water content prevents soil from retaining structure.
MOISTURE CONTENT
TERM
Occasional
Scattered
Numerous
Organic
PEAT
PERCENT BY VOLUME
0 to 1
1 to 10
10 to 30
30 to 50
50 to 100
ORGANIC CONTENT
AL
FC
GSD
ENV
SG
MD
C
UU
CU
CD
UCS
PERM
PP
TV
DS
ORG
PID
Atterberg Limits
Fines Content
Grain Size Distribution
Environmental Testing
Specific Gravity
Moisture Density Relationship
Consolidation
Unconsolidated Undrained Triaxial
Consolidated Undrained Triaxial
Consolidated Drained Triaxial
Unconfined Compression Strength
Hydraulic Conductivity Test
Pocket Penetrometer
Torvane
Direct Shear
Organic Content
Photoionization Detector Reading
LABORATORY TESTSSAMPLING METHOD
2” OD SPT Split Spoon Sample with
140 lb hammer falling 30” (ASTM D1587)
Core Run
No Recovery
Shelby Tube Sample (ASTM D1587)
3” OD Split Spoon Sample with 300 lb
hammer falling 30”
Grab Sample
Non Standard (As noted on log)
Boulders
Cobbles
Gravel
Coarse Gravel
Fine Gravel
Sand
Coarse Sand
Medium Sand
Fine Sand
Silt and Clay
Larger than 12 in.
3 in. to 12 in.
3 in. to No. 4 (4.75 mm)
3 in. to 3/4 in.
3/4 in. to No. 4 (4.75 mm)
No. 4 (4.75 mm) to No. 200 (0.075 mm)
No. 4 (4.75 mm) to No. 10 (2.00 mm)
No. 10 (2.00 mm) to No. 40 (0.425 mm)
No. 40 (0.425 mm) to No. 200 (0.075 mm)
Smaller than No. 200 (0.075 mm)
COMPONENT DEFINITIONS
STRUCTURE
SOIL CLASSIFICATION AND
EXPLORATION LOG KEY
FIGURE A-1
(Sheet 3 of 3)P:\MatLab\Secure\GEOTECH\FORMS\Office\Boring Log KeyGeotechnical Engineering
R1
R2
R3
R4
R0
R5
R6
Very Weak Rock
Weak Rock
Moderately Weak Rock
Strong Rock
Extremely Weak Rock
Very Strong Rock
Extremely Strong Rock
1.0 - 5.0
5.0 - 25
25 - 50
50 - 100
0.25 - 1.0
100 - 250
> 250
150 - 750
750 - 3,500
3,500 - 7,500
7,500 - 15,000
50 - 150
15,000 - 35,000
> 35,000
Crumbles under firm blows with point of geological hammer.
Can be peeled by a pocket knife with difficulty. Shallow indentation
made by firm blow with point of geological hammer.
Cannot be scraped or peeled with a pocket knife. Specimen can
be fractured with single firm blow of geological hammer.
Specimen requires more than one blow of geological hammer to
fracture it.
Can be readily indented, grooved or gouged with fingernail, or
carved with a pocketknife. Breaks with light manual pressure.
Specimen requires many blows of geological hammer to fracture it.
Specimen can only be chipped with geological hammer.
ROCK HARDNESS
Grade Description
WEATHERING
Term Description
Field Identification Approximate UCS (MPa)Approximate UCS (psi)
Slightly
Weathered
Moderately
Weathered
Highly
Weathered
Completely
Weathered
Fresh
Residual Soil
Discoloration indicates weathering of rock material and discontinuity surfaces. All the rock material may
be discolored by weathering and may be somewhat weaker externally than in its fresh condition.
Less than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock
is present either as a continuous framework or as core stones.
More than half of the rock material is decomposed and/or disintegrated to a soil. Fresh or discolored rock
is present either as a discontinuous framework or as core stones.
All rock material is decomposed and/or disintegrated to a soil. The original mass structure is still largely intact.
No visible sign of rock material weathering; perhaps slight discoloration on major discontinuity surfaces.
All rock material is converted to a soil. The mass structure and material fabric are destroyed.
There is a large change in volume, but the soil has not been significantly transported.
Close
Moderately Wide
Extremely Close
Very Wide
Extremely Wide
1.0 - 2.5 in.
2.5 - 8.0 in.
8.0 in. - 2.0 ft.
2.0 - 6.5 ft.
< 1.0 in.
6.5 - 20.0 ft.
> 20.0 ft.
2 - 6 cm
6 - 20 cm
20 - 60 cm
60 cm - 2 m
< 2 cm
2 - 6 m
> 6 m
DISCONTINUITY SPACING
English Metric
Percent Term
APERTURE WIDTH
CL
Ga
Ca
Fe
Qtz
Sd
Py
So
Mn
Clay
Gauge
Calcium Carbonate
Iron Oxide
Quartz
Sand
Pyrite
Sulfite
Manganese
INFILL TYPE
25 - 50
50 - 75
75 - 90
90 - 100
0 - 25
Poor
Fair
Good
Excellent
Very Poor
ROCK QUALITY DESIGNATION (RQD)
RQD & CORE RECOVERY CALCULATIONS
RQD = Sum of intact pieces > 4 inches (100 mm)
Total core run length
REC = Sum of core recovery (intact pieces)
Total core run length
INFILL THICKNESS
JOINT ROUGHNESS COEFFICIENT (JRC)
0 - 2
2 - 6
6 - 10
10 - 14
14 - 20 Very Rough
Rough
Slightly Rough
Smooth
Slickensided
FIELD TESTS
SP Spotty
N None
UCS
BTS
CAI
T
M
I
Unconfined Compressive Strength
Brazilian Tensile Strength
Cerchar Abrasivity Index
Triaxial Strength Testing
Moh’s Hardness / Mineral Content
Infiltration Testing (Packer System)
Near vertical edges evident
Some ridges, surface
abrasion
Asperities on surface can
be felt
Appears and feels smooth
Visible polishing, striated
surface
Very Close
Wide
Term DescriptionTermWidthJRC
Very Wide
Open
Moderately Open
Tight
Very Tight
> 10 mm
2.5 - 10 mm
0.5 - 2.5 mm
0.1 - 0.5 mm
< 0.1 mm
Term
Surface is grass and topsoil.
(Concrete debris encountered at approximately 10 inches
below ground surface. Driller moved to three other
locations (B-101B to B-101D) as shown on site map.
Concrete debris was encountered in all additional
explorations.)
Boring terminated at approximately 10 inches below
ground surface due to concrete debris. No groundwater
encountered. Surface restored with grass plug.
CONC.
0
PL Water Content %LL
FIGURE A-2
10 20 30 40 50
C114068
Blows per foot (SPT)
Penetration Resistance
LOG OF BORING B-101
Blows per foot (non-standard)
60GroundWater
Date Completed: 3/13/2019
Driller: Holocene Drilling, Inc.
Equipment: Diedrich D-50
Drilling Method: 4-1/4 inch ID HSA
Hammer System: Automatic
Approximate Location: In Cedar River Park, approximately 9.5 feet
from Cedar River north side bank wall and 3.5 feet W of sidewalk that
goes into the park from Cedar River Park Dr. (N: 178388 E: 1302746)
Surface Elevation: 38 NAVD88 Depth, ftSOIL DESCRIPTION
Cedar River Hatchery Broodstock
Collection Facility (BCF)
Replacement Project
Logged by: HKH Reviewed by: MS Sheet 1 of 1LOG OF BORING (2/1/11) CEDAR RIVER BROODSTOCK.GPJ DATA_TEMPLATE_(7-21-11).GDT 4/9/19Seattle Public Utilities
Geotechnical Engineering Lab testsDepth, ftSymbolRecovery, %USCSBlows/6"Samples0
5
0
5
Surface is forest duff and topsoil.
ALLUVIUM
Medium dense to dense, brown, SILTY fine to medium
SAND, few coarse sand and gravel; moist; scattered
organics (matter, roots).
(Encountered large tree root.)
Dense, gray, SILTY SANDY GRAVEL; wet; scattered
organics (tree root).
Very dense, gray, SILTY SAND, trace gravel; wet;
scattered organics (tree root).
SANDSTONE
Sandstone, gray, fine to medium grained, highly
weathered, very weak.
Becomes moderately weathered.
Borehole completed at 13.25 feet below ground surface
(bgs). Perched groundwater encountered at
approximately 7.5 feet bgs. Boring backfilled with
bentonite chips and cuttings and surface restored with
dirt plug.
SM
SM
GM
SM
1
2
3
4a
4b
5
100
67
100
100
100
0
PL Water Content %LL
FIGURE A-3
10 20 30 40 50
C114068
Blows per foot (SPT)
Penetration Resistance
LOG OF BORING B-102
Blows per foot (non-standard)
60GroundWater
Date Completed: 3/13/2019
Driller: Holocene Drilling, Inc.
Equipment: Diedrich D-50
Drilling Method: 4-1/4 inch ID HSA
Hammer System: Automatic
Approximate Location: On the south side of the Cedar River (CR), 32.5
ft S of the concrete boat launch and 24 ft W of the CL of the boat
launch near the CR Trail Trailhead. (N: 178276 E: 1302676)
Surface Elevation: 34 NAVD88 Depth, ftSOIL DESCRIPTION
Cedar River Hatchery Broodstock
Collection Facility (BCF)
Replacement Project
Logged by: HKH Reviewed by: MS Sheet 1 of 1LOG OF BORING (2/1/11) CEDAR RIVER BROODSTOCK.GPJ DATA_TEMPLATE_(7-21-11).GDT 4/9/19Seattle Public Utilities
Geotechnical Engineering Lab testsDepth, ftSymbolRecovery, %USCSBlows/6"Samples>>50/2.5"
>>50/3"
11,19,11
16,8,7
13,14,23
14,32,50/2.5"
15,50/3"
0
5
10
15
0
5
10
15
Surface is forest duff and topsoil.
ALLUVIUM
Medium dense, brown, SILTY fine to medium SAND, few
coarse sand and gravel; moist; scattered organics
(matter, rootlets), gravel layer at 3.5 feet below ground
surface.
Dense, brown, SILTY GRAVEL WITH SAND; wet; trace
organics (rootlets).
SANDSTONE
Sandstone, gray, fine to medium grained, highly
weathered, very weak.
Sandstone, gray, fine to medium grained, slightly
weathered, weak.
Borehole completed at 10.2 feet below ground surface
(bgs). Perched groundwater encountered at
approximately 5 feet bgs. Boring backfilled with bentonite
chips and cuttings and surface restored with dirt plug.
SM
SM
GM
1
2a
2b
3
4
73
100
100
0
0
PL Water Content %LL
FIGURE A-4
10 20 30 40 50
C114068
Blows per foot (SPT)
Penetration Resistance
LOG OF BORING B-103
Blows per foot (non-standard)
60GroundWater
Date Completed: 3/13/2019
Driller: Holocene Drilling, Inc.
Equipment: Diedrich D-50
Drilling Method: 4-1/4 inch ID HSA
Hammer System: Automatic
Approximate Location: On the south side of the Cedar River (CR), 44.5
ft S of the concrete boat launch and 35.5 ft E of the CL of the boat
launch near the CR Trail Trailhead. (N: 178244 E: 1302727)
Surface Elevation: 35 NAVD88 Depth, ftSOIL DESCRIPTION
Cedar River Hatchery Broodstock
Collection Facility (BCF)
Replacement Project
Logged by: HKH Reviewed by: MS Sheet 1 of 1LOG OF BORING (2/1/11) CEDAR RIVER BROODSTOCK.GPJ DATA_TEMPLATE_(7-21-11).GDT 4/9/19Seattle Public Utilities
Geotechnical Engineering Lab testsDepth, ftSymbolRecovery, %USCSBlows/6"Samples>>50/3"
>>50/0.5"
>>50/2"
7,9,14
15,31,50/3"
50/0.5"
50/2"
0
5
10
15
0
5
10
15
Surface is grass/topsoil.
FILL
Concrete debris.
(Driller notes easier drilling at approximately 7.5 ft below
ground surface (bgs))
Very dense, grayish brown, SILTY fine to medium SAND,
few gravel and coarse sand; moist.
Becomes trace coarse sand and gravel.
Concrete debris.
(Blows possibly overstated due to gravel in sampler shoe
at 15 ft bgs)
ALLUVIUM
Brown, SILTY fine to medium SAND, few coarse sand
and gravel; wet.
Grayish brown, fine to medium SANDY SILT, trace
coarse sand and gravel; wet.
Grayish brown, SILTY fine to medium SAND, few coarse
sand and gravel; wet.
Very dense, brown, GRAVEL WITH SILT AND SAND,
trace cobbles; wet.
Grayish brown, SILTY SAND, trace gravel; wet.
Gray, SILT; few sand, trace gravel and cobbles; moist.
Stiff and wet.
Boring completed at 26.5 feet below ground surface
(bgs). Groundwater encountered at approximately 17.5
feet bgs at time of drilling. Boring backfilled with bentonite
chips and cuttings and surface restored with grass plug.
FILL
CONC.
SM
CONC.
SM
ML
SM
GP-GM
SM
ML
1
2
3
4
5
6
7
8
9
10
11
12
100
100
100
100
100
100
100
100
100
100
100
100
0
PL Water Content %LL
FIGURE A-5
10 20 30 40 50
C114068
Blows per foot (SPT)
Penetration Resistance
LOG OF BORING B-201
Blows per foot (non-standard)
60GroundWater
Date Completed: 4/1/2019
Driller: Holocene Drilling, Inc.
Equipment: Geoprobe 8140LC
Drilling Method: 6-in OD casing, 4-in core barrel.
Hammer System: Automatic
Approximate Location: In Cedar River Park, approximately 9.5 feet
from Cedar River north side bank wall and 2.5 feet W of sidewalk that
goes into the park from Cedar River Park Dr. (N: 178387 E: 1302747)
Surface Elevation: 39 NAVD88 Depth, ftSOIL DESCRIPTION
Cedar River Hatchery Broodstock
Collection Facility (BCF)
Replacement Project
Logged by: HKH Reviewed by: MS Sheet 1 of 1LOG OF BORING (2/1/11) CEDAR RIVER BROODSTOCK.GPJ DATA_TEMPLATE_(7-21-11).GDT 4/9/19Seattle Public Utilities
Geotechnical Engineering Lab testsDepth, ftSymbolRecovery, %USCSBlows/6"Samples>>50/6"
>>50/4"
>>50/5"
50/6"
50/4"
50/5"
5,11,15
0
5
10
15
20
25
30
0
5
10
15
20
25
30
APPENDIX B
LABORATORY TESTING PROGRAM
Cedar River Hatchery BCF Replacement Project
DRAFT Geotechnical Report (60% Design)
June 2019
SPU GEOTECHNICAL ENGINEERING
B-1
APPENDIX B
LABORATORY TESTING PROGRAM
SPU Geotechnical Engineering representatives performed laboratory tests on selected soil
samples collected during our field investigation. The laboratory tests were conducted in
general accordance with appropriate ASTM test methods. The test procedures and test results
are discussed below.
Natural Water Content
Natural water content determinations were made on selected soil samples in general
accordance with ASTM D-2216, Standard Test Method for Laboratory Determination of
Water (Moisture) Content of Soil and Rock by Mass. Test results are graphically indicated at
the appropriate sample depth on the summary logs in Appendix A.
APPENDIX C
HISTORICAL EXPLORATIONS
Cedar River Hatchery BCF Replacement Project
DRAFT Geotechnical Report (60% Design)
June 2019
SPU GEOTECHNICAL ENGINEERING
C-1
APPENDIX C
HISTORICAL EXPLORATIONS
In addition to the explorations and laboratory test results presented in Appendices A and B,
respectively, we reviewed historical explorations to gain an understanding of the subsurface
conditions along the Project alignment. Figure 1 shows the approximate location of the
historical explorations in the vicinity of the Project alignment.
SPU Geotechnical Engineering is not responsible for the accuracy or completeness of
exploration logs that were completed by others.