HomeMy WebLinkAboutR_Geotechnical_Report_230126_v1Geotechnical Engineering Services
901 South Grady Way
Renton, Washington
for
Velmeir Acquisition Services, L.L.C.
January 26, 2023
Geotechnical Engineering Services
901 South Grady Way
Renton, Washington
for
Velmeir Acquisition Services, L.L.C.
January 26, 2023
17425 NE Union Hill Road, Suite 250
Redmond, Washington 98052
425.861.6000
Geotechnical Engineering Services
901 South Grady Way
Renton, Washington
File No. 22042-005-00
January 26, 2023
Prepared for:
Velmeir Acquisition Services, L.L.C.
5757 West Maple Road, Suite 800
West Bloomfield, Michigan 48322
Attention: Stephen J. Bock
Prepared by:
GeoEngineers, Inc.
17425 NE Union Hill Road, Suite 250
Redmond, Washington 98052
425.861.6000
Michael A. Gray, PE
Senior Geotechnical Engineer
Lyle J. Stone, PE
Associate Geotechnical Engineer
MAG:LJS:nld
Disclaimer: 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.
January 26, 2023 | Page i File No. 22042-005-00
Table of Contents
1.0 INTRODUCTION ............................................................................................................................................. 1
2.0 PROJECT DESCRIPTION ................................................................................................................................ 1
3.0 SUBSURFACE EXPLORATIONS .................................................................................................................... 1
4.0 SITE CONDITIONS .......................................................................................................................................... 1
4.1. Surface Conditions ...................................................................................................................................... 1
4.2. Subsurface Soil Conditions ........................................................................................................................ 2
4.3. Groundwater Conditions ............................................................................................................................. 2
5.0 ENVIRONMENTALLY CRITICAL AREAS ........................................................................................................ 2
5.1. Seismic Hazard Area ................................................................................................................................... 3
5.2. Wellhead Protection Area ........................................................................................................................... 3
6.0 CONCLUSIONS AND RECOMMENDATIONS ................................................................................................. 3
6.1. Summary ..................................................................................................................................................... 3
6.2. Earthquake Engineering ............................................................................................................................. 4
6.2.1. Liquefaction ................................................................................................................................... 4
6.2.2. Lateral Spreading .......................................................................................................................... 4
6.2.3. 2018 IBC Seismic Design Information ......................................................................................... 4
6.3. Temporary Dewatering ................................................................................................................................ 5
6.4. Excavation Support ..................................................................................................................................... 5
6.4.1. Excavation Considerations ............................................................................................................ 6
6.4.2. Temporary Cut Slopes ................................................................................................................... 6
6.5. Foundation Support .................................................................................................................................... 7
6.6. Deep Foundations ....................................................................................................................................... 7
6.6.1. Augercast Piles .............................................................................................................................. 7
6.6.1. Pin Piles .......................................................................................................................................... 9
6.7. Shallow Foundations ................................................................................................................................. 10
6.8. Ground Improvement ................................................................................................................................ 10
6.8.2. Foundation Support with Ground Improvement ........................................................................ 12
6.8.3. Foundation Support Without Ground Improvement .................................................................. 13
6.8.4. Construction Considerations ...................................................................................................... 13
6.9. Slab-on-Grade Floors ................................................................................................................................ 14
6.9.1. Subgrade Preparation ................................................................................................................. 14
6.9.2. Design Parameters ...................................................................................................................... 14
6.9.3. Below-Slab Drainage ................................................................................................................... 14
6.10. Below-Grade Walls .......................................................................................................................... 14
6.10.1. Other Cast-in-Place Walls ............................................................................................................ 15
6.10.2. Drainage ....................................................................................................................................... 15
6.11. Earthwork ........................................................................................................................................ 15
6.11.1. Subgrade Preparation ................................................................................................................. 15
6.11.2. Structural Fill................................................................................................................................ 15
6.12. Infiltration Feasibility ...................................................................................................................... 17
6.13. Recommended Additional Geotechnical Services ........................................................................ 18
January 26, 2023 | Page ii File No. 22042-005-00
7.0 LIMITATIONS ............................................................................................................................................... 18
8.0 REFERENCES .............................................................................................................................................. 18
LIST OF FIGURES
Figure 1. Vicinity Map
Figure 2. Site Plan
APPENDICES
Appendix A. Cone Penetration Tests Report
Appendix B. Boring Logs from Previous Studies
Appendix C. Report Limitations and Guidelines for Use
January 26, 2023 | Page 1
File No. 22042-005-00
1.0 INTRODUCTION
This report summarizes the results of GeoEngineers’ geotechnical engineering services for the
901 South Grady Way project in Seattle, Washington. The project site is located to the southeast of the
intersection of South Grady Way and Talbot Road South in the location of the decommissioned fueling
station for the previously occupied Sam’s Club. The large retail building to the east is currently occupied by
Home Depot. The site is shown relative to surrounding physical features on the Vicinity Map (Figure 1) and
the Site Plan (Figure 2). The NAVD88 datum was used to reference elevations in this report.
The purpose of this report is to provide preliminary geotechnical engineering conclusions and
recommendations for the design and construction of the planned development. GeoEngineers’
geotechnical engineering services have been completed in general accordance with our signed proposal
executed October 17, 2022.
2.0 PROJECT DESCRIPTION
The project includes the redevelopment of the site with a single-story medical facility constructed at grade.
The building is located well inside the property line so excavations for foundations are anticipated to be
completed using temporary cut slopes. Foundation support is anticipated to consist of either deep
foundations or shallow foundations and will be dependent on the required performance of the building
during a seismic event.
3.0 SUBSURFACE EXPLORATIONS
The subsurface conditions at the site were evaluated by completing two cone penetration tests (CPTs). The
CPT explorations, GEI-1 and GEI-2, were each advanced to depths of approximately 58 and 59.2 feet,
respectively, below existing site grades. The locations of the explorations are shown on Figure 2. A
description of the field exploration program and logs/plots of the CPT’s are presented in Appendix A, Cone
Penetration Tests Report.
The subsurface conditions at the site were also evaluated by reviewing the logs of selected explorations
from previous site evaluations in the project vicinity. The approximate locations of the previous explorations
are shown on Figure 2. The logs of explorations from previous projects referenced for this study are
presented in Appendix B, Boring Logs from Previous Studies.
4.0 SITE CONDITIONS
4.1. Surface Conditions
The planned building will be located on a new King County parcel that is comprised of portions of
Nos. 915460-0010 and 202305-9007 that is located southeast of the intersection between Talbot Road
South and South Grady Way. The new parcel will be approximately 1.94 acres. Existing site conditions
consist of at-grade landscaping and was the location of the fueling station for the previously occupied Sam’s
Club. The fueling station, including the underground storage tanks, has since been decommissioned as
January 26, 2023 | Page 2 File No. 22042-005-00
documented by Terracon in their 2019 report. Existing site grades are relatively flat with the majority of
existing site grades shown to vary from approximate Elevations 35 to 37 feet (NAVD88).
The site survey we received shows underground gas, water, and storm drain at, or in close proximity, to the
project site. We anticipate that other utilities are also located at or adjacent to the project site.
4.2. Subsurface Soil Conditions
GeoEngineers’ understanding of subsurface conditions is based on completion of two CPTs and a review
of previous explorations (standard penetration tests; SPT’s) completed at the project site for a previous
evaluation. The soils encountered at the site were interpreted as relatively shallow fill overlying alluvium
and underlain by sandstone. The approximate locations of the CPTs completed for this study, as well as the
previous explorations (SPT’s), are shown on Figure 2.
■ Fill was encountered below the pavement, where encountered, or ground surface and extended to
depths of up to approximately 11½ feet below site grades. The material generally consists of very loose
to loose coal, wood, sandstone, and shale fill.
■ Alluvium was encountered below the fill and extended to the depths of the boring or the sandstone,
where encountered. The material consisted of very loose to medium dense sand with variable silt and
gravel content as well as very soft to soft silt with variable sand and gravel content. Some borings
encountered organic silt or peat in limited thicknesses at depths greater than 10 feet.
■ Sandstone was indicated in one exploration below the alluvium at a depth of approximately 68 feet
below existing site grades. The material had measured blow counts greater than 100 blows per inch.
The boring was reported to advance two feet into the unit.
4.3. Groundwater Conditions
The CPTs completed at the site encountered groundwater near approximate Elevations 22 and 24 feet
(depth of between 12 and 14 feet below existing site grades). The previous explorations completed at the
site encountered groundwater at the time of drilling between approximate Elevations 24 and 28.5 feet
(depths of between 4.5 and 8 feet below previous site grades). Groundwater measurements were also
taken in the Terracon Environmental report for two monitoring wells that encountered groundwater
between depths of 7.3 and 7.7 feet below existing site grades.
Groundwater levels are expected to vary with season and in response to precipitation. Based on the
planned structure, we do not anticipate that structure excavations will extend deep enough to encounter
the groundwater table.
5.0 ENVIRONMENTALLY CRITICAL AREAS
GeoEngineers has reviewed the critical area (ECA) maps available online through the City of Renton (COR)
geographic information system (GIS) website. Based on our review of the COR GIS maps, the site is located
within a mapped Seismic Hazard Area and Wellhead Protection Area.
January 26, 2023 | Page 3 File No. 22042-005-00
5.1. Seismic Hazard Area
The entire site is mapped within a seismic hazard area. As noted above, GeoEngineers has completed
explorations at the site, and reviewed previous explorations, to evaluate the risk of liquefaction. The results
of the liquefaction analysis/assessment are discussed in more detail below.
5.2. Wellhead Protection Area
A wellhead protection area is present across the entire project site. We understand that imported fill
materials are required to be from a verifiable source in order to ensure it is clear of contaminants. The City’s
grading and excavation regulations require imported fill material in excess of 100 cubic yards have a source
statement certified by a qualified professional, or confirmed that the fill material was obtained from a
Washington State Department of Transportation (WSDOT) approved source which would be verified during
construction. We do not anticipate this volume of fill being used on the project.
6.0 CONCLUSIONS AND RECOMMENDATIONS
6.1. Summary
A summary of the geotechnical considerations 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.
■ The site is designated Site Class F per the 2018 International Building Code (IBC) due to the presence
of potentially liquefiable soils. Recommended seismic design parameters are provided in a subsequent
section.
■ We estimate that total liquefaction induced settlement could be up to 20 inches during a design level
earthquake based on the subsurface conditions encountered in explorations completed/reviewed for
this study. Differential settlements between similarly supported columns is estimated to be between 5
and 10 inches.
■ Temporary cut slopes are anticipated for use where foundations/structures extend below site grades.
■ Deep foundations are appropriate support options and may consist of augercast pile or small diameter
pipe piles (i.e. pin piles). The deep foundations would be constructed at grade and would reduce the
risk of settlement for the structure during a seismic event. The deep foundations would be required to
extend to bearing soils that are located between approximately 60 and 70 feet below site grades.
■ Shallow foundations bearing on ground improvement are considered appropriate for the site.
For shallow foundations bearing directly on improved ground, an allowable soil bearing pressure of
3,500 pounds per square foot (psf) may be used. We anticipate that ground improvement would need
to extend 30 to 45 feet below ground surface to adequately mitigate damaging differential settlement
in the design seismic case.
■ Conventional slabs-on-grade are considered appropriate for this site and should be underlain by a
6-inch-thick layer of clean crushed rock (for example, City of Seattle Mineral Aggregate Type 22). The
underslab drainage system is anticipated to consist of a perimeter foundation drain. If settlement of
the slabs-on-grade during a seismic event is not desired, then they can be supported on deep
foundations or ground improvement.
January 26, 2023 | Page 4 File No. 22042-005-00
Our specific geotechnical recommendations are presented in the following sections of this report.
6.2. Earthquake Engineering
6.2.1. Liquefaction
Liquefaction refers to the condition by which vibration or shaking of the ground, usually from earthquake
forces, results in the development of excess pore pressures in saturated soils with subsequent loss of
strength in the deposit of soil. In general, soils that are susceptible to liquefaction include very loose to
medium dense clean to silty sands and some silts that are below the water table.
The evaluation of liquefaction potential is a complex procedure and is dependent on numerous site
parameters, including soil grain size, soil density, site geometry, static stress, and the design ground
acceleration. Typically, the liquefaction potential of a site is evaluated by comparing the cyclic stress ratio
(CSR), which is the ratio of the cyclic shear stress induced by an earthquake to the initial effective
overburden stress, to the cyclic resistance ratio (CRR), which is the soils resistance to liquefaction.
We evaluated the liquefaction of the CPT’s using the CLIQ program and incorporated research by Cetin et
al. (2009) which accounts for the depth of the liquefiable layers when estimating settlement. These
methods predict the potential for up about 7 to 9 inches of free-field liquefaction induced settlement across
the site for the design earthquake event.
We evaluated the liquefaction of the SPT (boring B-25 from the ZZA 2002 report) based on triggering
potential (Youd et al. 2001; Idriss and Boulanger 2014) and liquefaction-induced settlement (Tokimatsu
and Seed 1987; Ishihara and Yoshimine 1992; Idriss and Boulanger 2014). These methods predict
between approximately 11 and 20 inches of free-field liquefaction induced settlement across the site for
the design earthquake event.
Differential settlements at the site could be on the order of 5 and 10 inches across the site.
It should be noted that the analysis we completed assumed a 2,475 return period for the structure.
6.2.2. Lateral Spreading
Lateral spreading involves lateral displacement of large, surficial blocks of soil as the underlying soil layer
liquefies. Lateral spreading can occur on near-level ground as blocks of surface soils are displaced relative
to adjacent blocks. Lateral spreading also occurs as blocks of surface soils are displaced toward a nearby
slope or free-face by movement of the underlying liquefied soil. Due to the depth of the potentially
liquefiable soils and the topography in the immediate site vicinity, it is our opinion that the risk of lateral
spreading occurring at the site is low.
6.2.3. 2018 IBC Seismic Design Information
Based on the results of our liquefaction analyses, the site is classified as Site Class F per ASCE 7-16
Section 20.3.1. If the fundamental period of vibration of the planned structure is greater than 0.5 seconds,
a site response analysis is required to determine the design acceleration parameters for the site, and
GeoEngineers should be contacted to provide revised recommendations. If the fundamental period of
vibration of the planned structure is less than or equal to 0.5 seconds, the exception presented in
ASCE 7-16 Section 20.3 is applicable, whereby a Site Class is permitted to be determined in accordance
January 26, 2023 | Page 5 File No. 22042-005-00
with Section 20.3 for the purpose of developing seismic design acceleration parameters only. All other
criteria associated with Site Class F sites still apply.
Based on the geotechnical explorations completed on site, we recommended Site Class D for developing
seismic design parameters for structures with fundamental periods of vibration less than or equal to
0.5 seconds. Table 1 provides the preliminary seismic design parameters per ASCE 7-16 Supplement 3
Section 11.4.8. Further, per ASCE 7-16 Supplement 3 Section 11.4.8, a ground motion hazard analysis
(GMHA) is required to determine the seismic design acceleration parameters for structures on Site Class D
sites with S1 greater than or equal to 0.2 unless the following exception is used, which has been
incorporated in the values provided in Table 1.
1. The value of the parameter SM1 determined by Eq. (11.4-2) is increased by 50 percent for all
applications of SM1. The resulting value of the parameter SD1 determined by Eq. (11.4-4) shall be used
for all applications of SD1.
TABLE 1. 2018 IBC SEISMIC PARAMETERS
2018 IBC Parameter1 Recommended Value
Site Class F
Short-period Spectral Response Acceleration, SS (g) 1.432
1-Second Period Spectral Response Acceleration, S1 (g) 0.488
Short-period Site Coefficient, FA 1.00
Long-period Site Coefficient, FV 1.81
Short-period MCER spectral response acceleration adjusted for site class, SMS (g) 1.432
Long-period MCER spectral response acceleration adjusted for site class, SM1 (g) 1.326
Short-period design spectral response acceleration adjusted for site class, SDS (g) 0.955
Long-period design spectral response acceleration adjusted for site class, SD1 (g) 0.884
Notes:
1 Parameters developed for Site Class D as permitted by ASCE 716 Section 20.3.1 based on latitude 47.4746465 and
longitude -122.2057309 using the Applied Technology Council (ATC) Hazards online tool (https://hazards.atcouncil.org/).
6.3. Temporary Dewatering
The groundwater table in the site vicinity is anticipated to be located between approximately 5 and 10 feet
below existing site grades. The regional groundwater or surface water from rain events that are likely to be
encountered in excavations extending deeper than 5 feet are anticipated to be manageable by means of
sumps and pumps. The flow rate will vary based on location, precipitation, season, and other factors. For
excavations deeper than 10 feet below existing grades, active temporary dewatering, such as vacuum
wellpoints may be required. GeoEngineers should be notified if excavations greater than 10 feet are
anticipated.
6.4. Excavation Support
The planned foundations are located offset from site boundaries or existing improvements and are
anticipated to be completed using temporary cut slopes. Excavation considerations and temporary cut
slopes are provided below.
January 26, 2023 | Page 6 File No. 22042-005-00
6.4.1. Excavation Considerations
The site soils may be excavated with conventional excavation equipment, such as trackhoes or dozers. The
fill on site may contain foundation elements and/or utilities from previous site development, debris, rubble
and/or cobbles and boulders. We recommend that procedures be identified in the project specifications
for measurement and payment of work associated with obstructions.
6.4.2. Temporary Cut Slopes
The stability of open-cut slopes is a function of soil type, groundwater seepage, slope inclination, slope
height and nearby surface loads. The use of inadequately designed open cuts could impact the stability of
adjacent work areas, could affect existing utilities and could endanger personnel.
The contractor performing the work has the primary responsibility for protection of workers and adjacent
improvements. In our opinion, the contractor will be in the best position to observe subsurface conditions
continuously throughout the construction process and to respond to variable soil and groundwater
conditions. Therefore, the contractor should have the primary responsibility for deciding whether to use
open-cut slopes for much of the excavations rather than some form of temporary excavation support, and
for establishing the safe inclination of the cut slope. Acceptable slope inclinations for utilities and ancillary
excavations should be determined during construction. Because of the diversity of construction techniques
and available shoring systems, the design of temporary cut slopes is most appropriately left to the
contractor proposing to complete the installation. Temporary cut slopes and shoring must comply with the
provisions of Chapter 296-155 Washington Administrative Code (WAC), Part N, “Excavation, Trenching and
Shoring.”
Temporary unsupported cut slopes more than 4 feet high may be inclined at 1.5H:1V (horizontal to vertical)
maximum steepness within the fill soils. For open cuts at the site, we recommend that:
■ No traffic, construction equipment, stockpiles or building supplies be allowed at the top of the cut
slopes within a distance of at least 5 feet from the top of the cut;
■ The cut slopes should be planned such that they do not encroach on a 1H:1V influence line projected
down from the edges of nearby or planned foundation elements.
■ Exposed soil along the slope be protected from surface erosion by using waterproof tarps or plastic
sheeting;
■ Construction activities be scheduled so that the length of time the temporary cut is left open is reduced
to the extent practicable;
■ Erosion control measures be implemented as appropriate such that runoff from the site is reduced to
the extent practicable;
■ Surface water be diverted away from the slope; and
■ The general condition of the slopes be observed periodically by the geotechnical engineer to confirm
adequate stability.
Water that enters the excavation must be collected and routed away from prepared subgrade areas. We
expect that this may be accomplished by installing a system of drainage ditches and sumps along the toe
of the cut slopes. Some sloughing and raveling of the cut slopes should be expected. Temporary covering,
January 26, 2023 | Page 7 File No. 22042-005-00
such as heavy plastic sheeting with appropriate ballast, should be used to protect these slopes during
periods of wet weather. Surface water runoff from above cut slopes should be prevented from flowing over
the slope face by using berms, drainage ditches, swales or other appropriate methods.
6.5. Foundation Support
The building foundations can be supported on either deep or shallow foundations. The determination of
the foundation support option (deep or shallow) will be dependent upon the desired performance of the
building during a seismic event. The followings sections provide recommendations for deep and shallow
foundation support.
6.6. Deep Foundations
Deep foundations are an appropriate foundation support method. The fill and alluvium soils are potentially
liquefiable and deep foundations can be constructed to the sandstone, which represents a competent
bearing layer. We have provided deep foundation recommendations in the following sections.
6.6.1. Augercast Piles
Augercast piles are constructed using a continuous-flight, hollow-stem auger attached to a set of leads
supported by a crane or installed with a fixed-mast drill rig. The first step in the pile casting process consists
of drilling the auger into the ground to the specified tip elevation of the pile. Grout is then pumped through
the hollow stem during steady withdrawal of the auger, replacing the soils on the flights of the auger.
The final step is to install a steel reinforcing cage and typically a center bar into the column of fresh grout.
One benefit of using augercast piles is that the auger provides support for the soils during the pile
installation process, thus eliminating the need for temporary casing or drilling fluid.
Installation of augercast piles also produces minimal ground vibrations.
6.6.1.1. Construction Considerations
Given the distinct contrast in stiffness between the alluvium and the underlying sandstone and the need to
develop pile capacity from the sandstone (bearing soils), it is important that the piles achieve a consistent
embedment into the sandstone. In order to confirm that the piles are consistently embedded into the
sandstone, we recommend that the contractor use drilling equipment capable of measuring and displaying
drill pressure and crowd speed during augercast pile installation. These measurements can be used as an
indication of the transition from alluvium to sandstone, which can be used to estimate pile embedment in
sandstone. Production piles located in close proximity to one of the previous geotechnical borings
completed at the project site and should be installed at the beginning of pile construction to calibrate the
drill pressure and crowd speed requirements for the alluvium and the sandstone. This process will provide
the required information to determine whether the piles have been installed to an appropriate length and
will eliminate the need for static pile load testing.
As is standard practice, the pile grout must be pumped under pressure through the hollow stem as the
auger is withdrawn. Maintenance of adequate grout pressure at the auger tip is critical to reduce the
potential for encroachment of adjacent native soils into the grout column. The rate of withdrawal of the
auger must remain constant throughout the installation of the piles in order to reduce the potential for
necking of the piles. Failure to maintain a constant rate of withdrawal of the auger should result in
immediate rejection of that pile. Reinforcing steel for bending and uplift should be placed in the fresh grout
January 26, 2023 | Page 8 File No. 22042-005-00
column as soon as possible after withdrawal of the auger. Centering devices should be used to provide
concrete cover around the reinforcing steel.
The contractor should adhere to a waiting period of at least 12 hours between the installation of piles
spaced closer than 8 feet, center-to-center. This waiting period is necessary to avoid disturbing the curing
concrete in previously cast piles.
Grout pumps must be fitted with a volume-measuring device and pressure gauge so that the volume of
grout placed in each pile and the pressure head maintained during pumping can be observed. A minimum
grout line pressure of 100 pounds per square inch (psi) should be maintained. The rate of auger withdrawal
should be controlled during grouting such that the volume of grout pumped is equal to at least 120 percent
of the theoretical pile volume. A minimum head of 5 feet of grout should be maintained above the auger
tip during withdrawal of the auger to maintain a full column of grout and to prevent hole collapse.
A qualified geotechnical engineer should observe the drilling operations, monitor grout injection
procedures, record the volume of grout placed in each pile relative to the calculated volume of the hole,
and evaluate the adequacy of individual pile installations.
6.6.1.2. Axial Capacity
Axial pile load capacity at this site is developed from a combination of end bearing and side resistance in
the bearing soils with some additional capacity attributed to side frictional resistance in soils located above
bearing soils. Uplift pile capacity will also be developed primarily from side frictional resistance in the
sandstone soils.
Table 2 below includes a summary of estimated allowable static and seismic capacities for an
18-inch-diameter augercast pile.
TABLE 2. SUMMARY OF ESTIMATED CAPACITIES
Pile Diameter
(Inches)
Embedment Depth
into Bearing Soils
Layer1 (feet)
Static Conditions Seismic Conditions2
Compression
(kips) Uplift (kips)
Compression
(kips) Uplift (kips)
18 10 370 260 310 25
Notes:
1 Full design embedment might not be achieved if massive or unfractured sandstone is encountered.
2 Seismic conditions consider the effects of liquefaction including soil strength loss and downdrag.
If piles are spaced at least three pile diameters on center, as recommended, no reduction of axial capacity
for group action is needed. The structural characteristics of pile materials and structural connections may
impose limitations on pile capacities and should be evaluated by the structural engineer. Full length steel
reinforcing will be needed for shafts subjected to uplift loads.
6.6.1.3. Lateral Capacity
Lateral loads can be resisted by passive soil pressure on the vertical piles and by the passive soil pressures
on the pile cap. Because of the potential separation between the pile-supported foundation components
and the underlying soil from settlement, base friction along the bottom of the pile cap should not be
included in calculations for lateral capacity.
January 26, 2023 | Page 9 File No. 22042-005-00
Piles spaced closer than eight pile diameters apart will experience group effects that will result in a lower
lateral load capacity for trailing rows of piles with respect to leading rows of piles for an equivalent
deflection. We recommend that the lateral load capacity for trailing piles in a pile group spaced three pile
diameters apart be reduced by a factor of 0.3. Reductions of the lateral load capacity for trailing piles at
spacings greater than three pile diameters but less than eight pile diameters apart can be linearly
interpolated.
If lateral capacities (deflection, shear and moment versus depth) are necessary they can be prepared during
the design phase.
We recommend that the passive soil pressure acting on the pile cap be estimated using an equivalent fluid
density of 250 pounds per cubic foot (pcf) where the soil adjacent to the foundation consists of adequately
compacted structural fill. This passive resistance value includes a factor of safety of 1.5 and assumes a
4-foot-deep pile cap and a minimum lateral deflection of 1 inch to fully develop the passive resistance.
Deflections that are less than 1 inch will not fully mobilize the passive resistance in the soil.
6.6.1.4. Pile Settlement
We estimate that the post-construction settlement of pile foundations, designed and installed as
recommended, will be on the order of ½ inch or less. Maximum differential settlement should be less than
about one-half the post-construction settlement. Most of this settlement will occur rapidly as loads are
applied.
6.6.1. Pin Piles
Small-diameter pipe piles, also known as pin piles, may be suitable for support of the foundation loads. We
recommend an allowable design load for 6- and 8-inch-diameter pipe piles driven to refusal criteria as
summarized in Table 3 below. Piles should be driven no closer together than 2 feet on center. We estimate
pile settlements on the order of ½ inch, occurring rapidly following load application.
We recommend that the 6- and 8-inch-diameter piles be installed using an excavator-mounted pneumatic
jackhammer with a hammer weight of at least 3,000 pounds. These preliminary capacities will be confirmed
during design based on specific hammer weights, pile diameters, and refusal criteria.
TABLE 3. PIN PILE DESIGN CRITERIA
Pile Diameter1 Seconds per inch Allowable Axial Compression2 (kips)
6-inch 6 30
8-inch 10 45
Notes:
1 Installed with a 3,000-pound hydraulic hammer.
2 Includes a factor or safety of 2.
Pile tip depths are typically estimated to extend to a depth of approximately 20 to 30 feet based on
achieving refusal criteria through friction resistance. However, we would recommend that the piles extend
to the bearing layer, located between approximately 60 and 70 feet below existing site grades. It is
recommended that the pile lengths be confirmed/estimated by a specialty contractor who has experience
with installing pin piles in similar soils and that driving the pin piles to bearing soils can be achieved at the
project site. Steel pipe piles have a risk of corrosion and are typically galvanized as a corrosion protection
January 26, 2023 | Page 10 File No. 22042-005-00
measure. Refusal criteria and pile capacities will need to be confirmed by completing a load test for each
pile type used. This is discussed in more detail below.
We recommend that for each proposed pile type and selected hammer, a load test pile be driven to assess
the ability to meet the driving criteria recommended above. The test piles should be loaded to at least
200 percent of the allowable design load. The pile load tests should be observed by a geotechnical
engineer from our firm. Pin pile load tests are typically accomplished by jacking against a large piece of
construction equipment. The equipment is centered over the top of the pile and a hydraulic jack equipped
with a hand-operated hydraulic pump and a pressure gauge is placed between the excavator and pile.
The load is applied in increments and downward deflection measurements are recorded at each load. The
load vs. deflection is plotted to determine the pile capacity and factor of safety.
Lateral resistance and deflections of pile foundations are governed primarily by the soil stiffness, fixity of
the top of the pile, the amount of allowable deflection, and the strength of the pile itself. We can estimate
lateral capacity of the pipe piles, as well as uplift capacity should the team choose this foundation support
method.
Allowable pile capacities are provided for Allowable Stress Design (ASD), and the allowable capacities are
for combined dead plus long-term live loads. The allowable capacities are based on the strength of the
supporting soils for the depths below the existing ground surface and include a factor of safety of 2. The
capacities apply to single piles. If piles are spaced at least three pile diameters on center, as recommended,
no reduction of the axial capacity for group action is needed.
6.6.1.1. Vibration Considerations
The upper soils at the site are relatively loose and do not transmit vibrations compared to denser/harder
soils. Therefore, we anticipate negligible vibrations will be transmitted to nearby buildings and do not
believe that vibration monitoring is necessary at this time. This recommendation should be revisited once
the final layout of the building is completed, and or pin pile layout is known.
6.7. Shallow Foundations
Shallow foundations may be suitable for the project site provided the foundations are supported on ground
improvement (stone columns) or provided the foundations/structure are designed to tolerate the
anticipated total/differential settlement during a seismic event.
6.8. Ground Improvement
6.8.1.1. Ground Improvement Types
Based on our understanding of soil conditions at the site, the proposed improvements, and our experience
with ground improvement in the project vicinity, we anticipate that stone columns or aggregate piers will
likely be the most cost-effective ground improvement method for this site.
Stone columns are a vibro-displacement based ground improvement method that involves driving a
vibratory probe into the ground to densify the surrounding soil and reduce the potential for soil liquefaction.
As the probe is removed, stone (crushed rock) is placed and compacted in the void left by the probe.
Typically, a 2- to 4-foot-diameter column of stone remains. Stone columns are most effective in loose sands
with few fines that will readily densify under vibratory energy. Stone columns are less effective in
January 26, 2023 | Page 11 File No. 22042-005-00
fine-grained or cohesive soils where there is no densification effect, and the improvement comes only from
replacing the softer soils with the stronger crushed rock.
Aggregate piers are similar to stone columns in that a column of crushed rock is installed into the soft soil
to densify the soil and provide soil reinforcement. The difference between aggregate piers and stone
columns is the means and methods of installing the rock and the equipment used. An aggregate pier uses
a vertical action ram to install and compact the crushed rock. A stone column uses horizontal vibration and
fluid jetting to construct the crushed rock column.
Other ground improvement methods, such as jet grout or deep soil mixing, are also feasible. These
cementitious methods are generally more expensive and are not typically used in the soil types present at
the site unless there are structures or other infrastructure very close to the site with significant limits to
allowable vibration or other disturbance.
6.8.1.2. Ground Improvement Design Criteria
The primary intent of the ground improvement design should be to mitigate the liquefaction hazard and
reduced settlement below the proposed structure. The ground improvement should cover the entire
building footprint and extend at least 5 feet beyond the footprint of the structure and should be included
below any critical infrastructure located outside of the main structure. We recommend the design of the
ground improvement, including the actual layout, length and minimum diameter of each column or pier, be
provided by the contractor performing the work and be based on the final foundation plan. At a minimum,
the ground improvement should extend about 30 to 45 feet below existing site grades. We recommend
that the ground improvement be designed to achieve the following minimum performance criteria. This
criteria must be reviewed by the structural engineer who will confirm that the criteria is acceptable.
■ Allowable soil bearing resistance of 3,500 psf with an allowable increase of one-third for transient
loading conditions.
■ Total long-term static settlement of 1 inch and differential static settlement of 0.5 inch over a distance
of 40 feet.
■ Differential liquefaction-induced settlement of 2 inches over a distance of 40 feet.
Based on the soil conditions observed in our explorations and the preliminary performance criteria provided
above, we recommend using a minimum ground improvement area replacement ratio of 12 percent for
budgeting purposes. This replacement ratio can be adjusted during design after the performance criteria
has been confirmed or in the field after the performance of the installation equipment and response of the
soil has been observed and tested.
The contractor performing the work should provide adequate verification that the specified performance
criteria has been achieved after ground improvement installation. This could include modulus tests on the
installed ground improvement to verify the specified bearing resistance was achieved and post-treatment
cone penetrometer tests (CPTs) to verify that the specified liquefaction mitigation was achieved. Please
note that pre-treatment CPT’s have already been completed for this study.
January 26, 2023 | Page 12 File No. 22042-005-00
6.8.2. Foundation Support
with Ground
Improvement
6.8.2.1. Bearing Surface Preparation and Minimum Foundation Dimensions
Once ground improvement is installed, footing excavations should expose the top of the column or pier
elements and confirm their location relative to the foundation. Foundation-bearing surfaces should be
thoroughly compacted to a dense, non-yielding condition. Loose or highly disturbed materials present at
the base of footing excavations between ground improvement elements should be removed or compacted.
The ground improvement designer may specify that a layer of compacted structural fill be placed between
the top of the ground improvement elements and the bottom of foundations. Foundation bearing surfaces
should not be exposed to standing water. Should water infiltrate and pool in the excavation, it should be
removed before placing structural fill or reinforcing steel.
We recommend a minimum width of 1.5 feet for continuous wall footings and 2 feet for isolated column
footings. All exterior footing elements should be embedded at least 18 inches below the lowest adjacent
external grade. Interior footings can be founded a minimum of 12 inches below the top of the floor slab.
6.8.2.2. Allowable Soil Bearing Resistance
Provided ground improvement meeting the performance criteria described above is installed, foundations
for the proposed structures within the ground improvement area may be designed assuming an allowable
soil bearing resistance of 3,500 psf. The provided bearing pressures apply to the total of dead and long-
term live loads and may be increased by one-third when considering total loads, including earthquake or
wind loads. These are net bearing pressures. The weight of the footing and overlying backfill can be ignored
in calculating footing sizes. The ground improvement designer must confirm that the allowable bearing
pressure stated above is achievable with their proposed design.
6.8.2.3. Foundation Settlement
We estimate that static settlement of footings underlain by ground improvement designed and constructed
as recommended will be less than 1 inch, with differential settlements of less than ½ inch between
comparably loaded isolated column footings or along 40 feet of continuous footing. Static settlement
estimates are in addition to the estimated post ground improvement liquefaction settlement provided in
Section 6.2 of this Report.
6.8.2.4. Lateral Resistance
The ability of the soil to resist lateral loads is a function of frictional resistance, which can develop on the
base of footings and slabs and passive resistance, which can develop on the face of below-grade elements
of the structure as these elements tend to move into the soil. The allowable frictional resistance on the
base of the footing may be computed using a coefficient of friction of 0.40 applied to the vertical dead-load
forces. The allowable passive resistance on the face of the footing or other embedded foundation elements
may be computed using an equivalent fluid density of 250 pcf for undisturbed site soils or structural fill
extending out from the face of the foundation element a distance at least equal to two and one-half times
the depth of the element. These values include a factor of safety of about 1.5.
The passive earth pressure and friction components may be combined, provided that the passive
component does not exceed two-thirds of the total. The passive earth pressure value is based on the
assumptions that the adjacent grade is level, and that groundwater remains below the base of the footing
January 26, 2023 | Page 13 File No. 22042-005-00
throughout the year. The top foot of soil should be neglected when calculating passive lateral earth pressure
unless the area adjacent to the foundation is covered with pavement or a slab-on-grade.
6.8.3. Foundation
Support Without
Ground Improvement
Improvements that can tolerate large differential settlement during a seismic event without risking life
safety or resiliency objectives of the primary structure can be supported on shallow foundations without
ground improvement. We recommend that foundations without ground improvement be underlain by an
18-inch-thick layer of structural fill as specified in the “Earthwork” section below. The structural fill should
be compacted as described in the “Fill Placement and Compaction Criteria” section below. Foundation
bearing surfaces should be thoroughly compacted to a dense, non-yielding condition. Loose or highly
disturbed materials present at the base of foundation excavations should be removed or compacted.
Foundation bearing surfaces should not be exposed to standing water. Should water infiltrate and pool in
the excavation, it should be removed before placing structural fill or reinforcing steel.
We recommend that foundations not underlain by ground improvement be proportioned using an allowable
soil bearing pressure of 2,000 psf. This is a net bearing pressure; the weight of the footing and overlying
backfill can be ignored in calculating footing sizes. We estimate that settlement of footings due to static
loads will be less than 1 inch. Differential settlements between comparably loaded isolated column footings
or along 50 feet of continuous footing is expected to be less than ½ inch under static loads. We have based
our estimates on isolated column loads of 10 kips and strip footing loads of 4 kips per linear foot. If loads
exceed these values, we should be contacted for revised estimates. Settlement is expected to occur rapidly
as loads are applied. Increased settlement should be expected if subgrades are disturbed. These
settlement values are in addition to the estimated liquefaction induced total and differential settlement
values presented in Section 6.2 above. Footings not underlain by ground improvement can be designed
using the same lateral resistance parameters presented above.
6.8.4. Construction Considerations
We recommend that the condition of all subgrade areas be observed by GeoEngineers to evaluate whether
the work is completed in accordance with our recommendations and whether the subsurface conditions
are as anticipated.
If soft areas are present at the footing subgrade elevation, the soft areas should be removed and replaced
with approved structural fill at the direction of GeoEngineers.
We recommend that the contractor consider leaving the subgrade for the foundations as much as 6 to
12 inches high, depending on soil and weather conditions, until excavation to final subgrade is required for
foundation reinforcement. Leaving subgrade high will help reduce damage to the subgrade resulting from
construction traffic for other activities.
The foundation recommendations provided in this report are intended for design and construction of
building foundations. These recommendations may not be appropriate for temporary construction elements
such as tower cranes, mobile cranes, manlifts, or other equipment. A qualified geotechnical engineer
should be consulted to provide foundation support recommendations for tower cranes, mobile cranes,
manlifts or other temporary construction equipment, as necessary.
January 26, 2023 | Page 14 File No. 22042-005-00
6.9. Slab-on-Grade Floors
Slabs-on-grade with below-slab drainage are appropriate for the site. The following sections provide design
recommendations for subgrade preparation, slab-on-grade design parameters, and below-slab drainage.
6.9.1. Subgrade Preparation
The exposed subgrade should be evaluated after site grading is complete. Probing should be used to
evaluate the subgrade. The exposed soil should be firm and unyielding, and without significant
groundwater. Disturbed areas should be recompacted if possible or removed and replaced with compacted
structural fill.
The site should be rough graded to approximately 1 foot above slab subgrade elevation prior to foundation
construction in order to protect the slab subgrade soils from deterioration from wet weather or construction
traffic. After the foundations and below-slab drainage system have been constructed, the remaining soils
can be removed to final subgrade elevation followed by immediate placement of the capillary break
material.
6.9.2. Design Parameters
Conventional slabs may be supported on-grade, provided the subgrade soils are prepared as recommended
in the “Subgrade Preparation” section above. We recommend that the slab be founded on structural fill
placed over the undisturbed site soils. For slabs designed as a beam on an elastic foundation, a modulus
of subgrade reaction of 200 pounds per cubic inch (pci) may be used for subgrade soils prepared as
recommended.
We recommend that the slab-on-grade floors be underlain by a 6-inch-thick capillary break consisting of
material meeting the requirements of Mineral Aggregate Type 22 (¾-inch crushed gravel), City of Seattle
Standard Specification 9-03.14.
Provided that loose soil is removed and the subgrade is prepared as recommended, we estimate that
slabs-on-grade will not settle appreciably.
6.9.3. Below-Slab Drainage
Specification of a vapor barrier requires consideration of the performance expectations of the occupied
space, the type of flooring planned and other factors, and is typically completed by other members of the
project team.
Structural elements (such as vaults, elevator pits, stairwells, sumps, etc.) that extend greater than 4 feet
below site grades should be evaluated for the installation of foundation drainage or designed for hydrostatic
pressures. GeoEngineers should be contacted to review these conditions.
6.10. Below-Grade Walls
We anticipate that small cast-in-place walls may be required for vaults, elevators, stairwells, sumps, etc. If
so, the following may be used for design of those structures.
January 26, 2023 | Page 15 File No. 22042-005-00
6.10.1. Other Cast-in-Place Walls
Conventional cast-in-place walls may be necessary for retaining structures located on-site. The lateral soil
pressures acting on conventional cast-in-place subsurface walls will depend on the nature, density and
configuration of the soil behind the wall and the amount of lateral wall movement that can occur as backfill
is placed.
For walls that are free to yield at the top at least 0.1 percent of the height of the wall, soil pressures will be
less than if movement is limited by such factors as wall stiffness or bracing. Assuming that the walls are
backfilled and drainage is provided as outlined in the following paragraphs, we recommend that yielding
walls supporting horizontal backfill be designed using an equivalent fluid density of 35 pcf (triangular
distribution), while non-yielding walls supporting horizontal backfill be designed using an equivalent fluid
density of 55 pcf (triangular distribution). For seismic loading conditions, a rectangular earth pressure equal
to 8H psf (where H is the height of the wall in feet) should be added to the active/at-rest pressures. Other
surcharge loading should be applied as appropriate. Lateral resistance for conventional cast-in-place walls
can be provided by frictional resistance along the base of the wall and passive resistance in front of the
wall in accordance with the “Lateral Resistance” discussion earlier in this report.
The above soil pressures assume that wall drains will be installed to prevent the buildup of hydrostatic
pressure behind the walls, as discussed in the paragraphs below.
6.10.2. Drainage
Positive drainage should be provided behind cast-in-place retaining walls/structures by placing a
minimum 2-foot-wide zone of Mineral Aggregate Type 17 (bank run gravel), City of Seattle Standard
Specification 9-03.14. A perforated drainpipe should be placed near the base of the retaining wall to
provide drainage. The drainpipe should be surrounded by a minimum of 6 inches of Mineral Aggregate Type
22 (¾-inch crushed gravel), City of Seattle Standard Specification 9-03.14, or an alternative approved by
GeoEngineers. The Type 22 material should be wrapped with a geotextile filter fabric meeting the
requirements of construction geotextile for underground drainage, WSDOT Standard Specification 9-33.
The wall drainpipe should be connected to a header pipe and routed to a sump or gravity drain. Appropriate
cleanouts for drainpipe maintenance should be installed. A larger-diameter pipe will allow for easier
maintenance of drainage systems.
As noted above, the flow rate for the planned excavation in the below-slab drainage and below-grade wall
drainage systems is anticipated to be less than 5 gallons per minute (gpm).
6.11. Earthwork
6.11.1. Subgrade Preparation
The exposed subgrade in structure and hardscape areas should be evaluated after site excavation is
complete. Disturbed areas should be recompacted if the subgrade soil consists of granular material. If the
disturbed subgrade soils consist of fine-grained soils, it will likely be necessary to remove and replace the
disturbed soil with structural fill unless the soil can be adequately moisture-conditioned and recompacted.
6.11.2. Structural Fill
6.11.2.1. Materials
Fill placed to for the following conditions will need to be specified as structural fill as described below:
January 26, 2023 | Page 16 File No. 22042-005-00
■ If structural fill is necessary beneath building foundations or slabs, the fill should meet the
requirements of Mineral Aggregate Type 2 or Type 17 (1¼-inch minus crushed rock or bank run gravel),
City of Seattle Standard Specification 9-03.10(1)A or 9-03.12, respectively.
■ Structural fill placed behind retaining walls should meet the requirements of Mineral Aggregate Type 17
(bank run gravel), City of Seattle Standard Specification 9-03.10.
■ Structural fill placed within utility trenches and below pavement and sidewalk areas should consist of
controlled density fill (CDF), or fill meeting the requirements of Mineral Aggregate Type 17 (bank run
gravel), City of Seattle Standard Specification 9-03.10.
■ Structural fill placed around perimeter footing drains, underslab drains, and cast-in-place wall drains
should meet the requirements of Mineral Aggregate Type 22 (¾-inch crushed gravel), City of Seattle
Standard Specification 9-03.9 or 9-03.10(3).
■ Structural fill placed as capillary break material should meet the requirements of Type 22 (¾-inch
crushed gravel), City of Seattle Standard Specification 9-03.9 or 9-03.10(3).
■ Structural fill placed as crushed surfacing base course below pavements and sidewalks should meet
the requirements of Mineral Aggregate Type 2 (1¼-inch minus crushed rock), City of Seattle Standard
Specification 9-03.10(1)A.
6.11.2.2. On-site Soils
The on-site soils (sand) are moisture-sensitive and generally have natural moisture contents higher than
the anticipated optimum moisture content for compaction. As a result, the on-site soils will likely require
moisture conditioning in order to meet the required compaction criteria during dry weather conditions and
will not be suitable for reuse during wet weather. Furthermore, most of the fill soils required for the project
have specific gradation requirements, and the on-site soils do not meet these gradation requirements.
Because of this we recommend that the earthwork contractor plan to import backfill material for the project.
If the contractor wants to use on-site soils for structural fill, GeoEngineers can evaluate the on-site soils for
suitability as structural fill, as required, during construction. It may be feasible to reuse on-site soils with
the addition of cement treatment. If cement treatment is considered, GeoEngineers can work with the
contractor to determine the soil/cement ratio and placement procedures.
6.11.2.3. Fill Placement and Compaction Criteria
Structural fill should be mechanically compacted to a firm, non-yielding condition. Structural fill should be
placed in loose lifts not exceeding 12 inches in thickness when using heavy compaction equipment and
6 inches in loose thickness when using hand operated compaction equipment. The actual thickness will be
dependent on the structural fill material used and the type and size of compaction equipment. Each lift
should be conditioned to the proper moisture content and compacted to the specified density before
placing subsequent lifts. Compaction of all structural fill at the site should be in accordance with the
ASTM D1557 (modified proctor) test method. Structural fill should be compacted to the following criteria:
■ Structural fill placed in building areas (supporting slab-on-grade floors) and in pavement and sidewalk
areas (including utility trench backfill) should be compacted to at least 95 percent of the maximum dry
density (MDD) estimated in general accordance with ASTM D 1557.
January 26, 2023 | Page 17 File No. 22042-005-00
■ Structural fill placed against subgrade walls should be compacted to between 90 and 92 percent. Care
should be taken when compacting fill against subsurface walls to avoid over-compaction and, hence
overstressing the walls.
We recommend that GeoEngineers be present during probing of the exposed subgrade soils for foundations
and pavement areas, and during placement of structural fill. We will evaluate the adequacy of the subgrade
soils and identify areas needing further work, perform in-place moisture-density tests in the fill to verify
compliance with the compaction specifications, and advise on any modifications to the procedures that
may be appropriate for the prevailing conditions.
6.11.2.4. Weather Considerations
Disturbance of near surface soils should be expected if earthwork is completed during periods of wet
weather. During dry weather, the soils will: (1) be less susceptible to disturbance; (2) provide better support
for construction equipment; and (3) be more likely to meet the required compaction criteria.
The wet weather season generally begins in October and continues through May in western Washington;
however, periods of wet weather may occur during any month of the year. For earthwork activities during
wet weather, we recommend that the following steps be taken:
■ The ground surface in and around the work area should be sloped so that surface water is directed
away from the work area.
■ The ground surface should be graded such that areas of ponded water do not develop.
■ The contractor should take measures to prevent surface water from collecting in excavations and
trenches.
■ Measures should be implemented to remove surface water from the work area.
■ Slopes with exposed soils should be covered with plastic sheeting or similar means.
■ The site soils should not be left uncompacted and exposed to moisture. Sealing the surficial soils by
rolling with a smooth-drum roller prior to periods of precipitation will reduce the extent to which these
soils become wet or unstable.
■ Construction traffic should be restricted to specific areas of the site, preferably areas that are surfaced
with materials not susceptible to wet weather disturbance.
■ Construction activities should be scheduled so that the length of time that soils are left exposed to
moisture is reduced to the extent practicable.
6.12. Infiltration Feasibility
A summary of groundwater measurements are provided in the groundwater conditions section above.
Based on discussions with the project civil engineer we understand that planned infiltration facilities would
likely extend a minimum of 8 feet below existing site grades. Based on these conditions the facilities would
likely extend into the groundwater or minimum separation requirements between the bottom of the
infiltration facility and the groundwater elevation would not be achieved. Therefore, we do not recommend
infiltration be completed at the site.
January 26, 2023 | Page 18 File No. 22042-005-00
6.13. Recommended Additional Geotechnical Services
The recommendations provided in this report are provided for preliminary planning and budgeting
purposes. We will need to revise our recommendations as the project advances and as the design develops.
GeoEngineers should be retained to review the project plans and specifications when complete to confirm
that our design recommendations have been implemented as intended.
During construction, GeoEngineers should evaluate foundation subgrades, evaluate structural backfill, and
provide a summary letter of our construction observation services. The purposes of GeoEngineers’
construction phase services are to confirm that the subsurface conditions are consistent with those
observed in the explorations and other reasons described in Appendix C, Report Limitations and Guidelines
for Use.
7.0 LIMITATIONS
We have prepared this report for the exclusive use of Velmeir Acquisition Services, L.L.C. and their
authorized agents for the 901 South Grady Way project in Renton, Washington.
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.
Please refer to Appendix C for additional information pertaining to use of this report.
8.0 REFERENCES
ASCE (2016). “SEI/ASCE 7-16, Minimum Design Loads for Buildings and Other Structures,” American
Society of Civil Engineers.
Cetin K.O., Bilge H.T., Wu J., Kammerer A. and Seed R.B., [2009]. “Probabilistic Models for Cyclic Straining
of Saturated Clean Sands.” J. Geotech. and Geoenv. Engrg., 135[3], 371-386.
City of Seattle, 2020. “Standard Specifications for Road, Bridge and Municipal Construction.”
International Code Council, 2018. “International Building Code.”
Idriss, I.M. and Boulanger, R.W., 2014. “CPT and SPT Based Liquefaction Triggering Procedures.”
Ishihara, K., and Yoshimine, M., 1992. “Evaluation of Settlements in Sand Deposits Following Liquefaction
During Earthquakes,” Soils and Foundations, 32(1), pp. 173-188.
Terracon Consultants, 2019, “Underground Storage Tank Permanent Removal from Service Report.”
Tokimatsu, K., and Seed, H.B., “Evaluation of Settlements in Sands Due to Earthquake Shaking,” Journal
of Geotechnical Engineering, ASCE, 113(GT8), 1987, pp. 861-878.
January 26, 2023 | Page 19 File No. 22042-005-00
Youd, et al., “Liquefaction Resistance of Soils: Summary Report from the 1996 NCEER and 1998
NCEER/NSF Workshops on Evaluation of Liquefaction Resistance of Soils,” Journal of
Geotechnical and Geoenvironmental Engineering, ASCE, October 2001, pp. 817-833.
Zipper Zeman Associates, 2002, “Subsurface Exploration and Geotechnical Engineering Evaluation,
Proposed Retail Development, S. Grady Way and Talbot Road, Renton, Washington.”
FIGURES
80thAveSRenton
M unic i pal
A irport
SW Langston Rd
S W 1 9 t h S t ShattuckAveSShattuckAveSS W 7 t h S tP
owellAveSWSW 3rd Pl
S 130 t h S t
S 134th St
S 1 3 2 n d S t
S W 1 2 t h S t
S 1 3 5th St
S
W
S
u
n
s
etBlvd Rai
ni
erAveSOakesdal
eAveSWS W 1 6 t h S tRe
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t
on
Ave S
ValleyFwyBoeing
Longacr es
Industr ial P ark
TalbotRdSS W 2 7t h S t
OakesdaleAveSW900
NE 4 t h S t
NE 5th Pl
N 4 t h S tGardenAveN
MainAveSN 3 r d S t
S E 160t h S tRentonAveSWellsAveSS4thStTalbotRdSS5thSt
S
18th
St
B
e
a
c
o
n
Wa
y
S
BensonRdSN
1
st
S
t
S 2 n d S t
N E 3 r d S t
TalbotRdSS 3 r d S t
116thAveSEPugetDrSEBensonDrSRiver v iew Par k -
RentonCedarRiver
Natural Zone
Cedar Riv er
Park -Renton
R e n t o n
S E 1 6 8 t h S t
S E 1 64th S t
113thAveSEBen
son
Rd
S
116thAveSEBensonDrS1
SITE
Vicinity Map
Figure 1
901 South Grady Way
Renton, Washington
3
A lpine Lak es
Wilderness
Kent
Tacoma
Seattle
Olympia
0 2,000
Feet
P:\22\22042005\GIS\2204200500_Project\2204200500_Project.aprx\2204200500_F01_VicinityMap Date Exported: 10/24/22 by maugustSource(s):
• ESRI
Coordinate System: NAD 1983 UTM Zone 10N
Disclaimer: This figure was created for a specific purpose and project. Any use of this figure
for any other project or purpose shall be at the user's sole risk and without liability to GeoEngineers.
The locations of features shown may be approximate. GeoEngineers makes no warranty or
representation as to the accuracy, completeness, or suitability of the figure, or data contained
therein. The file containing this figure is a copy of a master document, the original of which is
retained by GeoEngineers and is the official document of record.
Urgent Care
B-26
B-28
B-31
B-27
B-25
B-23
B-24
B-29
B-32
GEI-01
GEI-02
Figure 2
901 South Grady Way
Renton, Washington
Site Plan
P:\22\22042005\CAD\00\Geotech Report\2204200500_F02_Site Plan.dwg F02 Date Exported:11/29/2022 5:54 PM - by Majed FadhlW E
N
S
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.
Data Source: Apex Engineering. dated 09/02/2022.
& Barghausen Consulting Engineers. dated 07/28/2022.
Projection: WA State Plane, North Zone, NAD83, US Foot
Feet
0
Legend
60 60
Proposed Site Boundary
B-23 Boring by Zipper Zeman Associates, 2002
GEI-01 Cone Penetration Test by
GeoEngineers, 2022 (Current Study)
APPENDICES
APPENDIX A
Cone Penetration Tests Report
January 26, 2023 | Page A-1 File No. 22042-005-00
APPENDIX A
CONE PENETRATION TESTS REPORT
Subsurface soil and groundwater conditions were evaluated by completing two cone penetration tests
(CPTs; GEI-1 and GEI-2). The CPTs were completed by ConeTec, Inc. on November 2, 2022. The locations
of the CPTs were measured using handheld GPS equipment. The approximate CPT locations are shown on
the Figure 2.
CPT’s are a subsurface exploration technique in which a small-diameter steel tip with adjacent sleeve is
continuously advanced with hydraulically operated equipment. Measurements of tip and sleeve resistance
allow interpretation of the soil profile and the consistency of the strata penetrated. The tip resistance,
friction ratio and pore water pressure are recorded on the CPT logs. The logs of the CPT probes are included
in the attached report in Appendix A. The CPT soundings were backfilled in general accordance with
procedures outlined by the Washington State Department of Ecology.
PRESENTATION OF SITE INVESTIGATION RESULTS
901 South Grady Way Renton
Prepared for:
GeoEngineers, Inc
ConeTec Job No: 22-59-25016
--
Project Start Date: 02-NOV-2022
Project End Date: 02-NOV-2022
Report Date: 09-NOV-2022
Prepared by:
ConeTec Inc.
1237 S Director St
Seattle, WA 98108
-
Tel: (253) 397-4861
ConeTecWA@conetec.com
www.conetec.com
www.conetecdataservices.com
901 South Grady Way Renton
Introduction
The enclosed report presents the results of the site investigation program conducted by ConeTec Inc. for
GeoEngineers, Inc. at 901 S Grady Way, Renton, WA 98057. The program consisted of cone penetration
tests.
Project Information
Project
Client GeoEngineers, Inc.
Project 901 South Grady Way Renton
ConeTec project number 22-59-25016
An aerial overview from Google Earth including the CPTu test locations is presented below.
Rig Description Deployment System Test Type
C23-25Ton Truck Rig Integrated Push Cylinders CPTu
901 South Grady Way Renton
Coordinates
Test Type Collection Method EPSG Number
CPTu Consumer grade GPS 4326
Cone Penetrometers Used for this Project
Cone Description Cone
Number
Cross
Sectional
Area (cm2)
Sleeve
Area
(cm2)
Tip
Capacity
(bar)
Sleeve
Capacity
(bar)
Pore Pressure
Capacity
(bar)
EC870: T1500F15U35 870 15.0 225 1500 15 35
Cone 870 was used for all CPTu soundings
Cone Penetration Test (CPTu)
Depth reference Depths are referenced to the existing ground surface at the time of each
test.
Tip and sleeve data offset 0.1 meter
This has been accounted for in the CPT data files.
Additional plots • Advanced plots with Ic, Su, phi and N(60)/N1(60)
• Soil Behaviour Type (SBT) scatter plots
Calculated Geotechnical Parameter Tables
Additional information
The Normalized Soil Behaviour Type Chart based on Qtn (SBT Qtn) (Robertson,
2009) was used to classify the soil for this project. A detailed set of calculated
CPTu parameters have been generated and are provided in Excel format files in
the release folder. The CPTu parameter calculations are based on values of
corrected tip resistance (qt) sleeve friction (fs) and pore pressure (u2).
Effective stresses are calculated based on unit weights that have been assigned
to the individual soil behaviour type zones and the assumed equilibrium pore
pressure profile.
901 South Grady Way Renton
Limitations
This report has been prepared for the exclusive use of GeoEngineers, Inc. (Client) for the project titled
“901 South Grady Way Renton”. The report’s contents may not be relied upon by any other party without
the express written permission of ConeTec Inc. (ConeTec). ConeTec has provided site investigation
services, prepared the factual data reporting and provided geotechnical parameter calculations consistent
with current best practices. No other warranty, expressed or implied, is made.
The information presented in the report document and the accompanying data set pertain to the specific
project, site conditions and objectives described to ConeTec by the Client. In order to properly understand
the factual data, assumptions and calculations, reference must be made to the documents provided and
their accompanying data sets, in their entirety.
CONE PENETRATION TEST - eSeries
Cone penetration tests (CPTu) are conducted using an integrated electronic piezocone penetrometer and
data acquisition system manufactured by Adara Systems Ltd., a subsidiary of ConeTec.
ConeTec’s piezocone penetrometers are compression type designs in which the tip and friction sleeve
load cells are independent and have separate load capacities. The piezocones use strain gauged load cells
for tip and sleeve friction and a strain gauged diaphragm type transducer for recording pore pressure.
The piezocones also have a platinum resistive temperature device (RTD) for monitoring the temperature
of the sensors, an accelerometer type dual axis inclinometer and two geophone sensors for recording
seismic signals. All signals are amplified and measured with minimum sixteen-bit resolution down hole
within the cone body, and the signals are sent to the surface using a high bandwidth, error corrected
digital interface through a shielded cable.
ConeTec penetrometers are manufactured with various tip, friction and pore pressure capacities in both
10 cm2 and 15 cm2 tip base area configurations in order to maximize signal resolution for various soil
conditions. The specific piezocone used for each test is described in the CPT summary table presented in
the first appendix. The 15 cm2 penetrometers do not require friction reducers as they have a diameter
larger than the deployment rods. The 10 cm2 piezocones use a friction reducer consisting of a rod adapter
extension behind the main cone body with an enlarged cross sectional area (typically 44 millimeters
diameter over a length of 32 millimeters with tapered leading and trailing edges) located at a distance of
585 millimeters above the cone tip.
The penetrometers are designed with equal end area friction sleeves, a net end area ratio of 0.8 and cone
tips with a 60 degree apex angle.
All ConeTec piezocones can record pore pressure at various locations. Unless otherwise noted, the pore
pressure filter is located directly behind the cone tip in the “u2” position (ASTM Type 2). The filter is six
millimeters thick, made of porous plastic (polyethylene) having an average pore size of 125 microns (90 -
160 microns). The function of the filter is to allow rapid movements of extremely small volumes of water
needed to activate the pressure transducer while preventing soil ingress or blockage.
The piezocone penetrometers are manufactured with dimensions, tolerances and sensor characteristics
that are in general accordance with the current ASTM D5778 standard. ConeTec’s calibration criteria also
meets or exceeds those of the current ASTM D5778 standard. An illustration of the piezocone
penetrometer is presented in Figure CPTu.
CONE PENETRATION TEST - eSeries
Figure CPTu. Piezocone Penetrometer (15 cm2)
The ConeTec data acquisition systems consist of a Windows based computer and a signal interface box
and power supply. The signal interface combines depth increment signals, seismic trigger signals and the
downhole digital data. This combined data is then sent to the Windows based computer for collection
and presentation. The data is recorded at fixed depth increments using a depth wheel attached to the
push cylinders or by using a spring loaded rubber depth wheel that is held against the cone rods. The
typical recording interval is 2.5 centimeters; custom recording intervals are possible.
The system displays the CPTu data in real time and records the following parameters to a storage media
during penetration:
• Depth
• Uncorrected tip resistance (qc)
• Sleeve friction (fs)
• Dynamic pore pressure (u)
• Additional sensors such as resistivity, passive gamma, ultra violet induced fluorescence, if
applicable
CONE PENETRATION TEST - eSeries
All testing is performed in accordance to ConeTec’s CPTu operating procedures which are in general
accordance with the current ASTM D5778 standard.
Prior to the start of a CPTu sounding a suitable cone is selected, the cone and data acquisition system are
powered on, the pore pressure system is saturated with silicone oil and the baseline readings are recorded
with the cone hanging freely in a vertical position.
The CPTu is conducted at a steady rate of two centimeters per second, within acceptable tolerances.
Typically one meter length rods with an outer diameter of 1.5 inches (38.1 millimeters) are added to
advance the cone to the sounding termination depth. After cone retraction final baselines are recorded.
Additional information pertaining to ConeTec’s cone penetration testing procedures:
• Each filter is saturated in silicone oil under vacuum pressure prior to use
• Baseline readings are compared to previous readings
• Soundings are terminated at the client’s target depth or at a depth where an obstruction is
encountered, excessive rod flex occurs, excessive inclination occurs, equipment damage is likely
to take place, or a dangerous working environment arises
• Differences between initial and final baselines are calculated to ensure zero load offsets have not
occurred and to ensure compliance with ASTM standards
The interpretation of piezocone data for this report is based on the corrected tip resistance (qt), sleeve
friction (fs) and pore water pressure (u). The interpretation of soil type is based on the correlations
developed by Robertson et al. (1986) and Robertson (1990, 2009). It should be noted that it is not always
possible to accurately identify a soil behavior type based on these parameters. In these situations,
experience, judgment and an assessment of other parameters may be used to infer soil behavior type.
The recorded tip resistance (qc) is the total force acting on the piezocone tip divided by its base area. The
tip resistance is corrected for pore pressure effects and termed corrected tip resistance (qt) according to
the following expression presented in Robertson et al. (1986):
qt = qc + (1-a) • u2
where: qt is the corrected tip resistance
qc is the recorded tip resistance
u2 is the recorded dynamic pore pressure behind the tip (u2 position)
a is the Net Area Ratio for the piezocone (0.8 for ConeTec probes)
The sleeve friction (fs) is the frictional force on the sleeve divided by its surface area. As all ConeTec
piezocones have equal end area friction sleeves, pore pressure corrections to the sleeve data are not
required.
The dynamic pore pressure (u) is a measure of the pore pressures generated during cone penetration. To
record equilibrium pore pressure, the penetration must be stopped to allow the dynamic pore pressures
to stabilize. The rate at which this occurs is predominantly a function of the permeability of the soil and
the diameter of the cone.
CONE PENETRATION TEST - eSeries
The friction ratio (Rf) is a calculated parameter. It is defined as the ratio of sleeve friction to the tip
resistance expressed as a percentage. Generally, saturated cohesive soils have low tip resistance, high
friction ratios and generate large excess pore water pressures. Cohesionless soils have higher tip
resistances, lower friction ratios and do not generate significant excess pore water pressure.
A summary of the CPTu soundings along with test details and individual plots are provided in the
appendices. A set of files with calculated geotechnical parameters were generated for each sounding
based on published correlations and are provided in Excel format in the data release folder. Information
regarding the methods used is also included in the data release folder.
For additional information on CPTu interpretations and calculated geotechnical parameters, refer to
Robertson et al. (1986), Lunne et al. (1997), Robertson (2009), Mayne (2013, 2014) and Mayne and
Peuchen (2012).
PORE PRESSURE DISSIPATION TEST
The cone penetration test is halted at specific depths to carry out pore pressure dissipation (PPD) tests,
shown in Figure PPD-1. For each dissipation test the cone and rods are decoupled from the rig and the
data acquisition system measures and records the variation of the pore pressure (u) with time (t).
Figure PPD-1. Pore pressure dissipation test setup
Pore pressure dissipation data can be interpreted to provide estimates of ground water conditions,
permeability, consolidation characteristics and soil behavior.
The typical shapes of dissipation curves shown in Figure PPD-2 are very useful in assessing soil type,
drainage, in situ pore pressure and soil properties. A flat curve that stabilizes quickly is typical of a freely
draining sand. Undrained soils such as clays will typically show positive excess pore pressure and have
long dissipation times. Dilative soils will often exhibit dynamic pore pressures below equilibrium that then
rise over time. Overconsolidated fine-grained soils will often exhibit an initial dilatory response where
there is an initial rise in pore pressure before reaching a peak and dissipating.
Figure PPD-2. Pore pressure dissipation curve examples
PORE PRESSURE DISSIPATION TEST
In order to interpret the equilibrium pore pressure (ueq) and the apparent phreatic surface, the pore
pressure should be monitored until such time as there is no variation in pore pressure with time as shown
for each curve in Figure PPD-2.
In fine grained deposits the point at which 100% of the excess pore pressure has dissipated is known as
t100. In some cases this can take an excessive amount of time and it may be impractical to take the
dissipation to t100. A theoretical analysis of pore pressure dissipations by Teh and Houlsby (1991) showed
that a single curve relating degree of dissipation versus theoretical time factor (T*) may be used to
calculate the coefficient of consolidation (ch) at various degrees of dissipation resulting in the expression
for ch shown below.
ch =
T*∙a2 ∙√Ir
t
Where:
T* is the dimensionless time factor (Table Time Factor)
a is the radius of the cone
Ir is the rigidity index
t is the time at the degree of consolidation
Table Time Factor. T* versus degree of dissipation (Teh and Houlsby (1991))
Degree of
Dissipation (%) 20 30 40 50 60 70 80
T* (u2) 0.038 0.078 0.142 0.245 0.439 0.804 1.60
The coefficient of consolidation is typically analyzed using the time (t50) corresponding to a degree of
dissipation of 50% (u50). In order to determine t50, dissipation tests must be taken to a pressure less than
u50. The u50 value is half way between the initial maximum pore pressure and the equilibrium pore
pressure value, known as u100. To estimate u50, both the initial maximum pore pressure and u100 must be
known or estimated. Other degrees of dissipations may be considered, particularly for extremely long
dissipations.
At any specific degree of dissipation the equilibrium pore pressure (u at t100) must be estimated at the
depth of interest. The equilibrium value may be determined from one or more sources such as measuring
the value directly (u100), estimating it from other dissipations in the same profile, estimating the phreatic
surface and assuming hydrostatic conditions, from nearby soundings, from client provided information,
from site observations and/or past experience, or from other site instrumentation.
For calculations of ch (Teh and Houlsby (1991)), t50 values are estimated from the corresponding pore
pressure dissipation curve and a rigidity index (Ir) is assumed. For curves having an initial dilatory response
in which an initial rise in pore pressure occurs before reaching a peak, the relative time from the peak
value is used in determining t50. In cases where the time to peak is excessive, t50 values are not calculated.
Due to possible inherent uncertainties in estimating Ir, the equilibrium pore pressure and the effect of an
initial dilatory response on calculating t50, other methods should be applied to confirm the results for ch.
PORE PRESSURE DISSIPATION TEST
Additional published methods for estimating the coefficient of consolidation from a piezocone test are
described in Burns and Mayne (1998, 2002), Jones and Van Zyl (1981), Robertson et al. (1992) and Sully
et al. (1999).
A summary of the pore pressure dissipation tests and dissipation plots are presented in the relevant
appendix.
REFERENCES
ASTM D5778-12, 2012, "Standard Test Method for Performing Electronic Friction Cone and Piezocone
Penetration Testing of Soils", ASTM International, West Conshohocken, PA. DOI: 10.1520/D5778-12.
Burns, S.E. and Mayne, P.W., 1998, “Monotonic and dilatory pore pressure decay during piezocone tests”,
Canadian Geotechnical Journal 26 (4): 1063-1073. DOI: 1063-1073/T98-062.
Burns, S.E. and Mayne, P.W., 2002, “Analytical cavity expansion-critical state model cone dissipation in
fine-grained soils”, Soils & Foundations, Vol. 42(2): 131-137.
Jones, G.A. and Van Zyl, D.J.A., 1981, “The piezometer probe: a useful investigation tool”, Proceedings,
10th International Conference on Soil Mechanics and Foundation Engineering, Vol. 3, Stockholm: 489-495.
Lunne, T., Robertson, P.K. and Powell, J. J. M., 1997, “Cone Penetration Testing in Geotechnical Practice”,
Blackie Academic and Professional.
Mayne, P.W., 2013, “Evaluating yield stress of soils from laboratory consolidation and in-situ cone
penetration tests”, Sound Geotechnical Research to Practice (Holtz Volume) GSP 230, ASCE, Reston/VA:
406-420. DOI: 10.1061/9780784412770.027.
Mayne, P.W. and Peuchen, J., 2012, “Unit weight trends with cone resistance in soft to firm clays”,
Geotechnical and Geophysical Site Characterization 4, Vol. 1 (Proc. ISC-4, Pernambuco), CRC Press,
London: 903-910.
Mayne, P.W., 2014, “Interpretation of geotechnical parameters from seismic piezocone tests”, CPT’14
Keynote Address, Las Vegas, NV, May 2014.
Robertson, P.K., Campanella, R.G., Gillespie, D. and Greig, J., 1986, “Use of Piezometer Cone Data”,
Proceedings of InSitu 86, ASCE Specialty Conference, Blacksburg, Virginia.
Robertson, P.K., 1990, “Soil Classification Using the Cone Penetration Test”, Canadian Geotechnical
Journal, Volume 27: 151-158. DOI: 10.1139/T90-014.
Robertson, P.K., Sully, J.P., Woeller, D.J., Lunne, T., Powell, J.J.M. and Gillespie, D.G., 1992, “Estimating
coefficient of consolidation from piezocone tests”, Canadian Geotechnical Journal, 29(4): 539-550. DOI:
10.1139/T92-061.
Robertson, P.K., 2009, “Interpretation of cone penetration tests – a unified approach”, Canadian
Geotechnical Journal, Volume 46: 1337-1355. DOI: 10.1139/T09-065.
Sully, J.P., Robertson, P.K., Campanella, R.G. and Woeller, D.J., 1999, “An approach to evaluation of field
CPTU dissipation data in overconsolidated fine-grained soils”, Canadian Geotechnical Journal, 36(2): 369-
381. DOI: 10.1139/T98-105.
Teh, C.I., and Houlsby, G.T., 1991, “An analytical study of the cone penetration test in clay”, Geotechnique,
41(1): 17-34. DOI: 10.1680/geot.1991.41.1.17.
APPENDICES
The appendices listed below are included in the report:
• Cone Penetration Test Summary and Standard Cone Penetration Test Plots
• Advanced Cone Penetration Test Plots with Ic, Su(Nkt), Phi and N(60)Ic/N1(60)Ic
• Soil Behavior Type (SBT) Scatter Plots
• Pore Pressure Dissipation Summary and Pore Pressure Dissipation Plots
Cone Penetration Test Summary and Standard Cone Penetration Test
Plots
Job No:22-59-25016
Client:GeoEngineers, Inc.
Project:901 South Grady Way Renton
Start Date:02-Nov-2022
End Date:02-Nov-2022
CONE PENETRATION TEST SUMMARY
Sounding ID File Name Date Cone
Assumed 1
Phreatic
Surface
(ft)
Final
Depth
(ft)
Latitude2
(deg)
Longitude2
(deg)
GEI-01 22-59-25016_CP01 02-Nov-2022 EC870: T1500F15U35 14.0 58.0 47.47182 -122.20735
GEI-02 22-59-25016_CP02 02-Nov-2022 EC870: T1500F15U35 12.7 59.2 47.47144 -122.20719
Totals 2 soundings 117.2
1. Phreatic surface based on pore pressure dissipation test unless otherwise noted. Hydrostatic profile applied to interpretation tables
2. Coordinates were collected using a handheld GPS - WGS 84 Lat/Long
Sheet 1 of 1
0 100 200 300
0
5
10
15
20
25
30
35
40
45
50
55
60
65
qt (tsf)Depth (feet)0.0 1.0 2.0 3.0
fs (tsf)
0.0 2.5 5.0 7.5
Rf (%)
0 50 100 1500
u (ft)
0 3 6 9
SBT Qtn
GeoEngineers
Job No: 22-59-25016
Date: 2022-11-02 14:56
Site: 901 South Grady Way Renton
Sounding: GEI-01
Cone: 870:T1500F15U35
Max Depth: 17.675 m / 57.99 ft
Depth Inc: 0.025 m / 0.082 ft
Avg Int: Every Point
File: 22-59-25016_CP01.COR
Unit Wt: SBTQtn (PKR2009)
SBT: Robertson, 2009 and 2010
Coords: Lat: 47.47182 Long: -122.20735
Undefined
Sand Mixtures
Sand Mixtures
Silt Mixtures
Clays
Clays
Clays
Silt Mixtures
Silt Mixtures
Silt Mixtures
Silt Mixtures
Silt Mixtures
Silt Mixtures
Silt Mixtures
Clays
Silt Mixtures
Silt Mixtures
Clays
Silt Mixtures
Silt Mixtures
Sands
Sand Mixtures
Clays
Silt Mixtures
Sands
Sand Mixtures
Sands
Sand Mixtures
Sands
Sand Mixtures
Silt Mixtures
Sand Mixtures
Silt Mixtures
Clays
Organic Soils
Silt Mixtures
Sand Mixtures
Silt Mixtures
Sands
Sand Mixtures
Sand Mixtures
Silt Mixtures
Silt Mixtures
Silt Mixtures
Sands
Undefined
10.0
Ueq(ft)
Refusal Refusal Refusal Refusal
Equilibrium Pore Pressure (Ueq)Assumed Ueq Dissipation, Ueq achieved Dissipation, Ueq not achieved Hydrostatic Line
The reported coordinates were acquired from hand-held GPS equipment and are only approximate locations. The coordinates should not be used for design purposes.
Prepunch Prepunch Prepunch Prepunch
0 100 200 300
0
5
10
15
20
25
30
35
40
45
50
55
60
65
qt (tsf)Depth (feet)0.0 1.0 2.0 3.0
fs (tsf)
0.0 2.5 5.0 7.5
Rf (%)
0 50 100 1500
u (ft)
0 3 6 9
SBT Qtn
GeoEngineers
Job No: 22-59-25016
Date: 2022-11-02 13:45
Site: 901 South Grady Way Renton
Sounding: GEI-02
Cone: 870:T1500F15U35
Max Depth: 18.050 m / 59.22 ft
Depth Inc: 0.025 m / 0.082 ft
Avg Int: Every Point
File: 22-59-25016_CP02.COR
Unit Wt: SBTQtn (PKR2009)
SBT: Robertson, 2009 and 2010
Coords: Lat: 47.47143 Long: -122.20718
Undefined
Sand Mixtures
Undefined
Sands
Sand Mixtures
Clays
Silt Mixtures
Silt Mixtures
Clays
Clays
Sand Mixtures
Silt Mixtures
Sands
Sand Mixtures
Silt Mixtures
Silt Mixtures
Sands
Clays
Sand Mixtures
Silt Mixtures
Clays
Sand Mixtures
Sands
Sand Mixtures
Silt Mixtures
Clays
Sand Mixtures
Sand Mixtures
Sand Mixtures
Clays
Clays
Clays
Silt Mixtures
Sand Mixtures
Sands
Sand Mixtures
Sands
Sand Mixtures
Sand Mixtures
Sands
Sand Mixtures
Sands
Sand Mixtures
11.1
Ueq(ft)
Refusal Refusal Refusal Refusal
Equilibrium Pore Pressure (Ueq)Assumed Ueq Dissipation, Ueq achieved Dissipation, Ueq not achieved Hydrostatic Line
The reported coordinates were acquired from hand-held GPS equipment and are only approximate locations. The coordinates should not be used for design purposes.
Prepunch Prepunch Prepunch Prepunch
Prepunch Prepunch Prepunch Prepunch
Advanced Cone Penetration Test Plots with Ic, Su, Phi and N(60)/N1(60)
0 100 200 300
0
5
10
15
20
25
30
35
40
45
50
55
60
65
qt (tsf)Depth (feet)0 50 100 1500
u (ft)
1.0 2.0 3.0 4.0
Ic (PKR 2009)
0.0 1.0 2.0 3.0 4.0
Su (Nkt) (tsf)
20 30 40 50 60
Phi (deg)
0 10 20 30 40 50
N60 (Ic RW1998) (bpf)
GeoEngineers
Job No: 22-59-25016
Date: 2022-11-02 14:56
Site: 901 South Grady Way Renton
Sounding: GEI-01
Cone: 870:T1500F15U35
Max Depth: 17.675 m / 57.99 ft
Depth Inc: 0.025 m / 0.082 ft
Avg Int: Every Point
File: 22-59-25016_CP01.COR
Unit Wt: SBTQtn (PKR2009)
Su Nkt: 15.0
SBT: Robertson, 2009 and 2010
Coords: Lat: 47.47182 Long: -122.20735
10.0
Ueq(ft)
Refusal Refusal Refusal Refusal Refusal Refusal
Equilibrium Pore Pressure (Ueq)Assumed Ueq Dissipation, Ueq achieved Dissipation, Ueq not achieved Hydrostatic Line
N1(60) (bpf)
The reported coordinates were acquired from hand-held GPS equipment and are only approximate locations. The coordinates should not be used for design purposes.
Prepunch Prepunch Prepunch Prepunch Prepunch Prepunch
0 100 200 300
0
5
10
15
20
25
30
35
40
45
50
55
60
65
qt (tsf)Depth (feet)0 50 100 1500
u (ft)
1.0 2.0 3.0 4.0
Ic (PKR 2009)
0.0 1.0 2.0 3.0 4.0
Su (Nkt) (tsf)
20 30 40 50 60
Phi (deg)
0 10 20 30 40 50
N60 (Ic RW1998) (bpf)
GeoEngineers
Job No: 22-59-25016
Date: 2022-11-02 13:45
Site: 901 South Grady Way Renton
Sounding: GEI-02
Cone: 870:T1500F15U35
Max Depth: 18.050 m / 59.22 ft
Depth Inc: 0.025 m / 0.082 ft
Avg Int: Every Point
File: 22-59-25016_CP02.COR
Unit Wt: SBTQtn (PKR2009)
Su Nkt: 15.0
SBT: Robertson, 2009 and 2010
Coords: Lat: 47.47143 Long: -122.20718
11.1
Ueq(ft)
Refusal Refusal Refusal Refusal Refusal Refusal
Equilibrium Pore Pressure (Ueq)Assumed Ueq Dissipation, Ueq achieved Dissipation, Ueq not achieved Hydrostatic Line
N1(60) (bpf)
The reported coordinates were acquired from hand-held GPS equipment and are only approximate locations. The coordinates should not be used for design purposes.
Prepunch Prepunch Prepunch Prepunch Prepunch Prepunch
Prepunch Prepunch Prepunch Prepunch Prepunch Prepunch
Soil Behavior Type (SBT) Scatter Plots
GeoEngineers
Job No: 22-59-25016
Date: 2022-11-02 14:56
Site: 901 South Grady Way Renton
Sounding: GEI-01
Cone: 870:T1500F15U35
Legend
Sensitive, Fine Grained
Organic Soils
Clays
Silt Mixtures
Sand Mixtures
Sands
Gravelly Sand to Sand
Stiff Sand to Clayey Sand
Very Stiff Fine Grained
Depth Ranges
>0.0 to 7.5 ft
>7.5 to 15.0 ft
>15.0 to 22.5 ft
>22.5 to 30.0 ft
>30.0 to 37.5 ft
>37.5 to 45.0 ft
>45.0 to 52.5 ft
>52.5 to 60.0 ft
>60.0 to 67.5 ft
>67.5 to 75.0 ft
>75.0 ft
1
2
3
4
5
6
7 8
9
Qtn,cs = 70
Ic = 2.6
0.10 1.0 10.0
1.0
10.0
100
1000
Fr (%)QtnQtn Chart (PKR 2009)
Legend
Sensitive Fines
Organic Soil
Clay
Silty Clay
Clayey Silt
Silt
Sandy Silt
Silty Sand/Sand
Sand
Gravelly Sand
Stiff Fine Grained
Cemented Sand
1
2
3
4
5
6
7
8
9
10
11
12
0.0 2.0 4.0 6.0 8.0
1.0
10.0
100
1000
Rf(%)qt (bar)Standard SBT Chart (UBC 1986)
Legend
CCS (Cont. sensitive clay like)
CC (Cont. clay like)
TC (Cont. transitional)
SC (Cont. sand like)
CD (Dil. clay like)
TD (Dil. transitional)
SD (Dil. sand like)
CCS CC
TC
SC
CD
TD
SD
0.10 1.0 10.0
1.0
10.0
100
1000
Fr (%)QtnModified SBTn (PKR 2016)
GeoEngineers
Job No: 22-59-25016
Date: 2022-11-02 13:45
Site: 901 South Grady Way Renton
Sounding: GEI-02
Cone: 870:T1500F15U35
Legend
Sensitive, Fine Grained
Organic Soils
Clays
Silt Mixtures
Sand Mixtures
Sands
Gravelly Sand to Sand
Stiff Sand to Clayey Sand
Very Stiff Fine Grained
Depth Ranges
>0.0 to 7.5 ft
>7.5 to 15.0 ft
>15.0 to 22.5 ft
>22.5 to 30.0 ft
>30.0 to 37.5 ft
>37.5 to 45.0 ft
>45.0 to 52.5 ft
>52.5 to 60.0 ft
>60.0 to 67.5 ft
>67.5 to 75.0 ft
>75.0 ft
1
2
3
4
5
6
7 8
9
Qtn,cs = 70
Ic = 2.6
0.10 1.0 10.0
1.0
10.0
100
1000
Fr (%)QtnQtn Chart (PKR 2009)
Legend
Sensitive Fines
Organic Soil
Clay
Silty Clay
Clayey Silt
Silt
Sandy Silt
Silty Sand/Sand
Sand
Gravelly Sand
Stiff Fine Grained
Cemented Sand
1
2
3
4
5
6
7
8
9
10
11
12
0.0 2.0 4.0 6.0 8.0
1.0
10.0
100
1000
Rf(%)qt (bar)Standard SBT Chart (UBC 1986)
Legend
CCS (Cont. sensitive clay like)
CC (Cont. clay like)
TC (Cont. transitional)
SC (Cont. sand like)
CD (Dil. clay like)
TD (Dil. transitional)
SD (Dil. sand like)
CCS CC
TC
SC
CD
TD
SD
0.10 1.0 10.0
1.0
10.0
100
1000
Fr (%)QtnModified SBTn (PKR 2016)
Pore Pressure Dissipation Summary and Pore Pressure Dissipation Plots
Job No:22-59-25016
Client:GeoEngineers, Inc.
Project:901 South Grady Way Renton
Start Date:02-Nov-2022
End Date:02-Nov-2022
CPTu PORE PRESSURE DISSIPATION SUMMARY
Sounding ID File Name Cone Area
(cm2)
Duration
(s)
Test
Depth
(ft)
Estimated
Equilibrium Pore
Pressure Ueq
(ft)
Calculated
Phreatic
Surface
(ft)
GEI-01 22-59-25016_CP01 15.0 330.0 24.0 10.0 14.0
GEI-02 22-59-25016_CP02 15.0 350.0 23.8 11.1 12.7
Total Duration 11.3 min
Sheet 1 of 1
0 100 200 300 400
0.0
10.0
20.0
0.0
-10.0
-20.0
Time (s)Pore Pressure (ft)GeoEngineers
Job No:22-59-25016
Date:11/02/2022 14:56
Site:901 South Grady Way Renton
Sounding:GEI-01
Cone:870:T1500F15U35 Area=15 cm²
Trace Summary:
Filename:22-59-25016_CP01.ppd2
Depth:7.325 m / 24.032 ft
Duration:330.0 s
u Min:-13.6 ft
u Max:10.1 ft
u Final:10.1 ft
WT: 4.267 m / 13.999 ft
Ueq:10.0 ft
0 100 200 300 400
0.0
5.0
10.0
15.0
20.0
Time (s)Pore Pressure (ft)GeoEngineers
Job No:22-59-25016
Date:11/02/2022 13:45
Site:901 South Grady Way Renton
Sounding:GEI-02
Cone:870:T1500F15U35 Area=15 cm²
Trace Summary:
Filename:22-59-25016_CP02.ppd2
Depth:7.250 m / 23.786 ft
Duration:350.0 s
u Min:1.4 ft
u Max:13.2 ft
u Final:11.1 ft
WT: 3.869 m / 12.693 ft
Ueq:11.1 ft
APPENDIX B
Boring Logs from Previous Studies
January 26, 2023 | Page B-1 File No. 22042-005-00
APPENDIX B
BORING LOGS FROM PREVIOUS STUDIES
Included in this section are logs from previous studies completed in the immediate vicinity of the project
site.
■ The logs of nine borings (B-23 through B-29, B-31, and B-32) completed by Zipper Zeman Associates
in 2002 for the Renton Retail project.
r
FIELD EXPLORATION PROCEDURES AND LOGS
J-1470
Our field exploration program for this project included 43 borings and 3 cone
penetrometer probes advanced between September 19, 2002 and October 10, 2002. The
approximate exploration locations are shown on Figure 1, the Site and Exploration Plan.
Exploration locations were determined by measuring distances from existing site features with a
tape relative to an undated Draft Grading and Drainage Plan prepared by PacLand. As such, the
exploration locations should be considered accurate to the degree implied by the measurement
method. The following sections describe our procedures associated with the explorarion.
Descriptive logs of the explorations are enclosed in this appendix.
Soil Boring Procedures
Our exploratory borings were advanced using track- and truck-mounted drill rigs
operated by an independent drilling firm working under subcontract to our firm. The borings
were completed utilizing hollow-stem auger and mud rotary drilling methods. An experienced
geotechnical engineer from our firm continuously observed the borings logged the subsurface
conditions encountered, and obtained representative soil samples. All samples were stored in
moisture-tight containers and transported to our laboratory for further visual classification andF,`
testing. After each boring was completed, the borehole was bacicfilled with soil cuttings and
bentonite clay.
r
Throughout the drilling operation, soil samples were obtained at 2.5- to 5-foot depth
intervals by means of the Standard Penetration Test(ASTM: D-1586). This testing and sampling
procedure consists of driving a standard 2-inch outside diameter steel split spoon sampler 18
inches into the soil with a 140-pound hammer free falling 30 inches. The number of blows
required to drive the sampler through each 6-inch interval is recorded, and the total number of
blows struck during the final 12 inches is recorded as the Standard Penetration Resistance, or
s blow count" (N value). If a total of 50 blows is struck within any 6-inch interval, the driving is
stopped and the blow count is recorded as 50 blows for the actual penetration distance. The
resulting Standard Penetration Resistance values indicate the relative density of granular soils
and the relative consistency of cohesive soils.
Undisturbed samples were obtained by pushing a 3-inch outside diameter, seamless steel
I
Shelby tube into the soil using the hydraulic system on the drill rig in accordance with ASTM:D-
1587. Since the thin wall tube is pushed rather than driven, the sample obtained is considered to
r be relatively undisturbed. The samples were classified in the field by examining the ends of the
tube prior to sealing with plastic caps. The samples were then transported to our laboratory
where they were extruded for further classification and laboratory testing.
The enclosed boring logs describe the vertical sequence of soils and materials
encountered in each boring, based primarily upon our field classifications and supported by our
subsequent laboratory examination and testing. Where a soil conta.ct was observed to be
gradational, our logs indicate the average contact depth. Where a soil type changed between
sample intervals, we inferred the contact depth. Our logs also graphically indicate the blow
T" count, sample type, sample number, and approximate depth of each soil sample obtained from
the boring, as well as any laboratory tests performed on these soil samples. If any groundwater
was encountered in a borehole, the approximate groundwater depth, and date of observation, is
FIELD EXPLORATION PROCEDURES AlV'D LOGS
J-1470
Our field explorarion program for this project included 43 borings advanced between
October September 19, 2002 and October 10, 2002. The approxunate exploration locations are
shown on Figure 1, the Site and Exploration Plan. Exploration locations were deternuned by
measuring distances from exisring site features with a tape relative to an undated Draft Grading
and Drainage Plan prepared by PacLand. As such, the exploration locations should be
considered accurate to the degree implied by the measurement method. The following sections
describe our procedures associated with the exploration. Descriptive logs of the explorations are
enclosed in this appendix.
Soil Boring Procedures
Our exploratory borings were advanced using track- and truck-mounted drill rigs
operated by an independent drilling firm working under subcontract to our firm. The borings
were completed utilizing hollow-stem auger and mud rotary drilling methods. An experienced
geotechnical engineer from our firm continuously observed the borings logged the subsurface
conditions encountered, and obtained representative soil samples. All samples were stored in
moisture-tight containers and transported to our laboratory for further visual classification and
testing. After each boring was completed, the borehole was backfilled with soil cuttings and
bentonite clay.
Throughout the drilling operation, soil samples were obtained at 2.5- to 5-foot depth
intervals by means of the Standard Penetration Test(ASTM: D-1586). This testing and sampling
procedure consists of driving a standard 2-inch outside diameter steel split spoon sampler 18
inches into the soil with a 140-pound hammer free falling 30 inches. The number of blows
required to drive the sampler through each 6-inch interval is recorded, and the total number of
blows struck during the final 12 inches is recorded as the Standard Penetration Resistance, or
blow count" (N value). If a total of 50 blows is struck within any 6-inch interval, the driving is
stopped and the blow count is recorded as 50 blows for the actual penetration distance. The
resulting Standard Penetration Resistance values indicate the relative density of granular soils
and the relative consistency of cohesive soils.
Undisturbed samples were obtained by pushing a 3-inch outside diameter, seamless steel
Shelby tube into the soil using the hydraulic system on the drill rig in accordance with ASTM:D-
1 87. Since the thin wall tube is pushed rather than driven, the sample obtained is considered to
be relatively undisturbed. The samples were classified in the field by examining the ends of the
tube prior to sealing with plastic caps. The samples were then transported to our laboratory
where they were extruded for further classification and laboratory testing.
The enclosed boring logs describe the vertical sequence of soils and materials
encountered in each boring, based primarily upon our field classifications and supported by our
subsequent laboratory examination and testing. Where a soil contact was observed to be
gradational, our logs indicate the average contact depth. Where a soil type changed between
sample intervals, we inferred the contact depth. Our logs also graphically indicate the blow
count, sample type, sample nurnber, and approximate depth of each soil sample obtained from
the boring, as well as any laboratory tests performed on these soil samples. If any groundwater
was encountered in a borehole, the appro cimate groundwater depth, and date of observation, is
I
depicted on the log. Groundwater depth estimates are typically based on the moisture content of
soil samples, the wetted portion of the drilling rods, the water level measured in the borehole
after the auger has been extracted.
The boring logs presented in this appendix are based upon the drilling action, observation
of the samples secured, laboratory test results, and field logs. The various types of soils are
indicated as well as the depth where the soils or characteristics of the soils changed. It should be
noted that these changes may have been gradual, and if the changes occurred between samples
intervals, they were inferred.
Electric Cone Penetrometer Probes
A local exploration company under subcontract to our firm performed three electric cone
penetrorneter probes for this project on Septernber 26, 2002. The descriptive soil interpretations
presented on the cone penetrometer probe logs have been developed by using this classification
chart as a guideline. It consists of a steel cone that is hydraulically pushed into the ground at up
to 40,000 pounds of pressure. Sensors on the tip of the cone collect data. Standard cone
penetrometers collect information to classify soil type by using sensors that measure cone-tip
pressure and friction. The detailed interpretive logs of the static cone penetrometer probes
accomplished for this study are presented subsequently.
PROJECT:Renton Retail JOB NO. J-1470 BORING B-23 PAGE 1 OF
Location: Renton,WA Approximate Elevation: 34.5 feet
Soil Description Penetration Resistance y
am a m
c 0 Standard Blows per foot Other
o v v Z C7 Z F-
0 10 20 30 40
1.5±inches ASPHALT above 3 inches medium
dense,damp,brown,gravelty SAND above loose,
L _ _ _ _' _ 1 '_ _ "
moist,black,pinic,and red,silty SAND with trace
GRAVEL(coal a d shale fragments)
f T T T __ __
S_ 1- - ,- - - ; ;-- ; -- ; - - ; -- ; - - ,o nnc
5
SZ s nnc
Very loose,wet,black,pink,red,silty SAND(coal and __ _ qTp _ _ _
shale fragments)
S-3 MC 3 3 MC
r- Q
Very soft,wet,gray,SILT and fine sandy SILT i , ; ; ; ' ; ; ;2
Boringcompletedat11.5feetonS/25/02.
Groundwater encountered at approximately 7.5 feet at
time of drilling.
r ' _r" r ' _ * '
15
i- -;-- -- ; - -;--'-- - - --- --
r --;- -; - - ; -- r--r-- : - -,--,--
A.
Z
i , , , , , ,
25
Explanation o o Zo so ao so
Monitoring Well Key
I 2-inch O.D.split spoon sample Moisture Content
0 Clean Sand
3-inch I.D Shelby.tube sample Cuttings Plastie Limit Naturel Liquid Limit
No Recovery Bentonite
Grout
Groundwater level at time of drilling
ATD or date of ineasurement B Screened Casing
Zipper Zeman Associates,Inc.BORING LOG Figure A-1
Geotechnical8 Environmental Consultants
Date Drilled:9125l02 Logged By:DCW
PROJECT: Renton Retail JOB NO. J-1470 BORING B-24 PAGE 1 OF
Location: Renton,WA Approximate Elevation: 34 feet
Soii Description
L Penetration Resistance a
x
y
Q- °'a a
m Standard Biows per foot Other j H
o Nl v Z C9 Z I°i
0 70 20 30 40
4±inches ASPHALT above 4.5±inches medium
dense,damp,brown,graveliy SAND above very loose, --_—____
moist,grading to wet,Wack and reddish orange,silty
SAND(coal and sedimentary rocfc fragments-fill) w
r ' ' r ' 'r' _ ____' , ___'' 7 '_
S i--; - - , _ . ; __ 3 MC
5
S-2 3 MC
r - - ; -- ,- - ----1 --;-- --
aTo ---- - --- - - •--•- • -•- --- --
3_3 2 MC
Very soft,wet,gray,SILT and sandy SILT
r
10
S
Boringcompletedat11.5feeton9/25/02. 1- ----
Groundwater encountered at approximately 6.5 feet at
time of drilfing. r _ 'r' ' r''T'''_ '
5
i , . .
r.-,
Z
f_ f _ _ ! __ _ _T__T __T_ _ T_____
I ' ' ' I
Explanation o o Zo so ao. so
I
Monitoring Well Key
2-inch O.D.split spoon sample
0 Clean Sand
Moisture Content
3-inch I.D Shetby tube sample Cuttings Plastic Limit Natural Liquid Limk
No Recovery Bentonite
Grout
Groundwater level at time of drilling
ATD or date of ineasurement Screened Casing
Zipper Zeman Associates,Inc.BORING LOG Figure A-1
Geotechnical&Environmental Consultants
Date Drilled:9J25IO2 Logged By: DCW
PROJECT: Renton Retail JOB NO. J-1470 BORING 8-25 PAGE 1 OF 3
Location: Renton,WA Approximate Elevation: 33 feet
Soii Description Penetration Resistance
t aa a 3 ; c
Q F z Standard Blows perfoot Other Z
0 10 20 30 40
inc es asp a over in es oose,mois, ar
brown,silry,graveliy SAND(Fiq)
r-
f _' f_ _ _ _ _ i __ i_ _ _ , _
Loose,mast,black,COALTAILINGS(Fill)
S-1 6
5
Very loose,moist,black,COAL TAILINGS(Fill)5-z 3
i- - - ; - . - -;-- --; , -- --
ATD
g_g 5
Soft,wet,dark brown,ORGANIC SILT with sorne sand
1 O
interbedded with gray,SAND with some s lt and gravel
G
S-4 7 GSA
Loose,saturated,gray SAND with some gravel and _
Vacesilt
i .
i
r ' ' r' 'r ' ' r''r'' r''t' 'i
15
Loose,wet,gray,silty SAND with some organics,Vace S-5 M''
8 2U0
gravel interbedded with sandy SILT i - ;- - ; ' "; '" ; ''; "';' '; '-'- -
20
Grades to medium dense
S-6 11 GSA
i . , --' - -
r-- , -- - - ,--, --
r - 25
Explanation o o zo so ao so
Monitoring Well Key
f ` I 2-inch O.D.spiit spoon sample Clean Sand
Moistu e Content
3-inch I.D Shelby tube sample CUttiflg5 Plastic Limit Natural Liquid Limit
No Recovery
Bentonite
Grout
Groundwater level at time of drilling
AT°or date of ineasurement 8 Screened Casing
Zipper Zeman Associates,tnc.BORING LOG Figure A-1
Geotechnical 8 Environmental Consultants
Date Drilled:9/24l02 Logged By CRT
PROJECT: Renton Retail JOB NO. J-1470 BORING B-25 PAGE 2 OF 3
Location: Renton,WA Approximate Elevation: 33 feet
Soil Description
m
Penetration Resistance
r aa aa :; 0 c
Q N N Z
SWndard Blows per foot Other > m
0 10 20 30 40
Z
Medium dense to dense,wet,gray,gravelly SAND to S_
sandy GRAVEL with some silt,Vace organics
c_-
f __ i _T __T__T_ __ __
T`
r i
30
s-s 2a
z 35
s-s 20
1- - - L - - -1 - -i-- 1- ---
j i . i i i .
i i i i i
r ' ' r _' r ' ' r " _r_ ' t' 'r'' '''r
40
Loose to medium dense,wet,gray,silty SAND with 5-10 11
some gravel with interbedded PEAT(3')
k r - - --r -- r --r- - --- ---- --
6
i , i
i . i
45
Medium dense to dense,wet,gray,gravelly SAND with S-11 37 I
somesiltandtraceorganics
1 '' L" 1''' ''
Medium dense,wet,gray,silty SAND with some gravel
and peaty organics(1^,i -- f '- f ' ' I- 'T'T''T' 'T''?' '
50
Explanation o io zo so ao so
Monito ing Well Key
I2-inch O.D.split spoon sample
0 Clean Sand
MOiSture Content
3-inch I.D Shelby tube sample Cuttings plastic Limit Natural uquw um c
No Recovery Bentonite
Grout
Groundwater level at time of drilling
ATD or date of ineasurement B Screened Casing
Zipper Zeman Associates,Inc.BORING LOG Figure A-1
Geotechnical8 Environmental Consultants
Date Drilled:9124/02 Logged By:CRT
PROJECT:Renton Retaii JOB NO. J-1470 BORING 8-25 PAGE 3 OF 3
Location: Renton,WA Approximate Elevation: 33 feet
Soil Description Penetration Resistance y
c ` 0 caaa °:
Q N Z Standard Blaws per foot Other
0 10 20 30 40
Z
Medium dense,wet,gray,silty SAND with some grevel 12 zo
and peaty organics(t")
t
1- -1 --
i i i i .
I
f _T _ i __
1 _
T _ T T t
t__ _ i__a__1__ __ .
I
nmm
i i i i
55
Medium dense,wet,gray,silty,fine SAND S-13 17
g;z
60
Loose,wet,gray,silty SAND interbedded with sandy _— S-14 9
SILT
i--1- -'--
i i i
i
T_ _ i __1__
L_'
1 _ _ __
L_l__ 1__ __ _'
65
Medium dense,saturated,gray,silty SAND interbedded __^ 5-15 20
withsandySlLT
Very dense,damp,light gray,silty SANDSTONE
70
oar
Boring completed at 70 feet on 9l24/02 S-16
Groundwater seepage observed at 6.5 feet at time of
driliing
1 ' - '
t ' '- -, --
f_t _ _ _ _ __T_ T_ _ T ' __
75
Explanation o 0 2o ao ao so
Monitoring Wetl Key
I
F : I 2-inch O.D.split spoon sample Moisture Content
Clean Sand
3-inch I.D Shelby tube sampie Cuttings Plastie Limit Natural Uquid L(mit
No Recovery Bent nite
Grout
Groundwater levei at time of drilling
f....
ATD or date of ineasurement 8 Screened Casing
Zipper Zeman Associates, Inc.BOR NG LOG Figure A-1
Geotechnical& Environmental Consultants
Date Drilied: 9/2M02 Lagged By: CRT
PROJECT:Renton Retail JOB NO. J-1470 BORING B-26 PAGE 1 OF
Location: Renton,WA Approximate Elevation: 32 feet
Soil Description Penetration Resistance
i = `
fl' a a- w
m 0 16 Standard Bbws per foot Other j y
G tn V Z C7 Z H
0 10 20 30 40 50
urface grave over medium dense,moist,brown,silry,
sandy GRAVEL(RII)
T _ ' ' t_T_ _ T__ i_ '
Loose,moist,black,silty SAND,COAL TAILINGS,
some organic wood dabris(Fill)
S 11
5
Very loose,moist,block,silty SAND with COAL S-2 3
TAILINGS wootl debris and organics(F11)
Very soft,wet,black,organic SILT with some wood — -
MC=1az%
iragments 3
ATD . -
I - - --' -- ' -- ' - - , -- - --
1 ATT
Very soft,wet to saturated,greenish ray,sandy SILT S-4 1 MC
with some day interbedded with silty SAND
t-- - ,
w
i _- _ _ t T _T_ T_ i __
i r i i i
L L 1 1 1 1 1
15
Ve soft,wet,bro ra ,sil SAND interbedded with
M tt676
Y 9 Y tY S-5 2 200W
siItySANDa dPEAT(4")
20
Medium dense,wet,gray,sitry SAND with some brow
organics and Vace gravel S-6 16
Boring completed at 21.5 feet on 9/26/02
Groundwater seepage observed at B feet at time of
driiling 1 - -; -- --- ; - , -'--
T _ __ T__7 _ __
25
Explanation o o 2o so ao so
I
Monitoring Well Key
2-inch O.D.split spoon sample Moisture Content
Clean Sand
3-inch!.D Shelby tube sample Cuttings Plastic Limit Naturel Liquid Limft
No Recovery Bentonite
Grout
Groundwater level at time of drilling
ATD
or date of ineasurement B Screened Casing
Zipper Zeman Associates,Inc.BORING LOG Figure A-1
Geotechnicai&Environmental Consultants
Date Drilled: 9126102 Logged By: CRT
PROJECT:Renton Retail JOB NO. J-1470 BORING B-27 PAGE 1 OF
Location: Renton,WA Approximate Elevation: 31 feet
Soil Description Penetration Resistance H
m °' m = ctaaa ::
Q.3 0 1° Standard Blows per foot Other y
o f 2 C7 Z 1
0 10 20 30 40
Medium dense gradi g to very loose,moist grading to
wet(below 4.5 feet),brown,gray,and black,grevelly,
s'silty SAND(Fill) k
r - - r - - r - - *- - - -' -t--
a'' ' "'a'"1''
S-1 16 MC
r - - ; - - r - - r - -r --
i --,-- ; ,--
5 ATD - -` -- ` -- ` - - `--` - - '--'- - ' -- '--
S-z
r- - r - - r•- ; - , -
3 MC
Soft to very soft,wet,gray,SILT with interbeds of
saturated,greenish-gray,fine to medium SAND,
irtegular horizons of fibrous wganics up to 0.25 inches
hick S_3 3
10
s-a
Boringcompletedat11.5feeton9/25/02. 1-- '- -1-- -
i_
Groundwater encountered at approximately 4.5 feet at
timeofdriilin9
15
20
i ; -
T_ _ i_ _ _ ' __l'_
GJ
Expianation o 0 20 3 ao so
Monitoring Well Key
I2-inch O.D.split spoon sample
Clean Sand
Moisture Content
3-inch I.D Shelby tube sample Cuttings plastie Umit Natural uquia um c
No Recovery
Bentonite
Grout
Groundwater level at time of driiling
ATD or date of ineasurement E Screened Casing
Zipper Zeman Associates,Inc.BORlNG LOG Figure A-1
Geotechnical& Environmental Consuftants
Date Drilled:9/25l02 Logged By:DCW
PROJECT: Renton Retail JOB NO. J-1470 BORING B-28 PAGE 1 OF
Location: Renton,WA Approximate Elevation: 32.5 feet
Soil Description
m 6
Penetration Resistance y
L aa a y 0 3 c
a Standard Blows per foot Other j y
C t/ t/ Z C7 3
Z H
0 10 20 30 40
Loose to medium dense,damp,brown,gravelly SAND
Fillj
r'' ' ' r'" r''T"'r'_i'_t"'
Medium stiff to soft,moist to wet,dark brown,sandy
SILT with some fine organics(FI1) S-t 1 5 MC
5
S'2
1 -- ;- !- -; -r -- 1 -- - ' _ 3 MC
qTp
Very soft.wet.9raY.SILT with some wood fiber g g 1 MC
horizons
10
2
Boringcompletedat11.5feeton9l25/02. i --1 - - = - -
Groundwater encountered at approximately 7.5 feet at
v
time of drilling. r '' r' ' r ' " r ''T ''T' " . t '
15
20
L - '- - '- i --
i f T ' T_'T_T_ 1 1 __
25
Explanation o o Zo so ao so
Monitoring Well Key
I2-inch O.D.split spoon sample
Clean Sand
MolstU e Content
3-inch I.D Shelby tube sample Cuttings Plastic Limit Natural Llqutd Llmlt
No Recovery
Bentonite
Grout
Groundwater level at time of drilling
ATo or date of ineasurement B Screened Casing
Zipper Zeman Associates,Inc.BORING LOG Figure A-1
Geotechnical 8 Environmental Consultants
Date Drilled:9/25102 Logged By: DCW
PROJECT:Renton Retail JOB NO. J-1470 BORING B-29 PAGE 1 OF
Location: Renton,WA Approximate Elevation: 33 feet
Soil Description Penetration Resistance yma orG1 0 3 =Q m O. = 41
m a
i°
Standard Btows per foot Other y
o V7 fn Z (7 3 Z H
0 10 20 30 40
3.5±inches ASPHALT above 4±of inedium dense,
damp,brown,gravelly SAND above very loose,moist, _____________ i _ _ _ _ __ _: __
black,silty SAND(coal fragments)with scattered
horizons of brown,gravelly SAND(FiA)
r -- ------- - - - -
s-' 3 MC
5
s-z L - -; - ` -. -;- -.- _ , _ _ Mc
A - - - -- - - - - -- - • - ; - -• -- --
Very loose,saturated,gray,fine SAND with some sitty
zones and scattered fibrous organics r-- --; -'; '' , ' -- - -; -
S'3 1 MC
10
Bonngcompletedat11.5feeton9/25/02.
Groundwater e countered at approximately 7.0 feet at
time of drilling.
r- - r--r - -r-- r' -T-'1 '
5
i i
2
i , , , - --
r --*--r - -r-- r -1- -t --
25
Explanation o o zo so ao 50
Monitoring Well Key
I2-inch O.D.split spoon sample Clean Sand
Moisture Content
3-inch t.D Shelby tube sample Cuttings Plasdc Llmit Natural Liquid Um(t
No Recovery
Bentonite .
Grout
Groundwater level at time of drilling
ATD or date of ineasurement B Screened Casing
Zipper Zeman Associates,Inc.BORING LOG Figure A-1
Geotechnical 8 Environmental Consultants
Date Drilled:9/25102 Logged By: DCW
PROJECT: Renton Retail JOB NO. J-1470 BORING B-30 PAGE 1 OF
Location: Renton,WA Approximate Elevation: 34 feet
Soil Description
D
Penetration Resistance y
r
m d - m a
r a a °' °;
Qy y Z Siandard Blows perfoot Other Z
0 10 20 30 40
Medium dense,damp,brown,gravelly SAND(Fill)
i
r-- r''r- -r- -r -- 't'-T'- -'
Very loose,mast grading to saturated,black,red,and
beige,silty SAND and sandy SILT(coal fragments-filq
S-1 M 5856 3 MC
5
S-2
A. ; -- ;- - - - ;- - i -- ; -- - - ,MF-59x 2 MC
r-- ; -- --r -;- ;- ;--
g'3 MC=58% 1 MC
Very stiff,wet,gray,SILT with trace fine SAND and
fibrous organics S-4 0
Boringcompletedat11.5feeton9/25/02. 1--, -- ,
Groundwater encountered at approximately 5.5 feet at
time of drilling.
r'-r--r--r"r- , -T-- r--1-
1 - 1 --
a '' -' '- '- --
15
20
1 - -L -- i- -1- -
r __ f __ ' T _ _T__T''T'_ _ '
2g
Explanation o o Zo so ao so
I
Monitoring Well Key
2-inch O.D.split spoon sample Clean Sand
Moisture Content
3-inch I.D Shelby tube sample Cuttings Plastie Lfmft Naturel Uquld Limit
No Recovery Bentonite
Grout
Groundwater level at time of drilling
aro or date of ineasurement B Screened Casing
Zipper Zeman Associates,Inc.BORING LOG Figure A-1
Geotechnical 8 Environmental Consultants
Date Drilled:9/25IO2 Logged By:DCW
PROJECT:Renton Retail JOB NO. J-1470 BORING B-31 PAGE 1 OF 1
Location: Renton,WA Approximate Elevation: 32 feet
Soii Description Penetration Reslstance
c
y a a °. :'
o N Z Standard Bbws per foot Other j FZ
0 10 20 30 40
Medium dense grading to very loose,damp to moist,
brown and dark gray,silty SAND with trace gravel(Fill) —_-----_
r - -- - -, -- - -r- -,--.--, - -
r- S i -- 3 MC
5 ----------------------------------------------
Verysoft.wet,darkbrownandgray,SlLTwithsome -- ---
fine sand and organic material interbeds S-2 i ; ; ; i ; ; 1
0 MC
r--
ATD
Loose to very loose,saturated,grey,fine SANO with
some fine and fibrous organics S-3 5 MC
10
4
Boring completed at 11.5 feet on 8/25/02. L _ _L__1__1. _ l __
Groundwater encountered at approximately 7.5 feet at
time of drilling.
w- - r ''r'' r "'r ' 'r' 'r' , _' T' '' '
15
20
1- -1 --i- -1 - -
T ' 'T_ _ T _ _T_' 1
25
Explanation o o zo so ao so
Monitoring Well Key
I2-inch O.D.split spoon sample
Clean Sand
Moisture Content
3-inch I.D Shelby tube sample Cuttings plastic limit Nawr Uquid Ltmit
No Recovery Bentonite
Grout
Groundwater level at time of drilling
ATD or date of ineasurement B Screened Casing
Zipper Zeman Associates,Inc.BORING LOG Figure A-1
Geotechnlcal&Environmental Consultants
Date Drtlled:9/25l02 Logged By:DCW
PROJECT:Renton Retail JOB NO. J-1470 BORING B-32 PAGE 1 OF
Location: Renton,WA Approximate Elevation: 33 feet
Soil Description Penetration Resistance
x mm d °' `
Y a °.
Q y y Z Standard Blaws perfoot Other FZ
0 10 20 30 40
Medium dense,damp,brown,silty,gravelly SAND(FII)
T _ _'._i' _T__T. 'i'_ "
Medium stiff,moist to wet,black and brown,silty SAND _ _
coal fragments-fill)
S , t- - - - - - - -: , ,5 200
1 - -; - - ; - -
r- -r - - , -,--,--
5 ATD
Very loose,wet,black,SAND with some fine roots and g_2 MC=5i9 Z MC
wood fibers(coal fragments-fill)
r - -r--r - - r ; - ; - - ; --;- ; -
Very loose,saturated,gray-brown,fine SAND
S'3 4 MC
10
s-a 3
Boring completed at 11.5 feet on 9/25l02. L_' L_ '1' 1' "1 '_
f'''Groundwater encountered at approximately 4.5 feet at
Gme of drilling.
w- r"" r'" r "r "r'_r_' '1"7 '
2
L ,
f ' ' T ' _T_ _ _T'-T__l __
25
Explanation o io zo ao ao so
Monitoring Well Key
I2-inch O.D.split spoon sample
Clean Sand
MoiStu e Content
3-inch I.D Shelby tube sample Cuttings Plastie LimR Na uroi Liquid Limit
No Recavery
Bentonite
Grout
Groundwater level at time of drilling
aro or date of ineasurement B Screened Casing
Zipper Zeman Associates,inc.BORING LOG Figure A-'1
Geotechnical&Environmental Consultants
Date Drilled:9125/02 Logged By:CRT
APPENDIX C
Report Limitations and Guidelines for Use
January 26, 2023 | Page C-1 File No. 22042-005-00
APPENDIX C
REPORT LIMITATIONS AND GUIDELINES FOR USE 1
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 Velmeir Acquisition Services, L.L.C. 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 901 South Grady Way project in Renton, 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.
January 26, 2023 | Page C-2 File No. 22042-005-00
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.
January 26, 2023 | Page C-3 File No. 22042-005-00
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 contractors 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.
January 26, 2023 | Page C-4 File No. 22042-005-00
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.
If Client desires these specialized services, they should be obtained from a consultant who offers services
in this specialized field.