geotechnical reportEarthSolutionsNWLLC
EarthSolutions
NW LLC
15365 N.E.90th Street,Suite 100 Redmond,WA 98052
(425)449-4704 Fax (425)449-4711
www.earthsolutionsnw.com
Geotechnical Engineering
Construction Observation/Testing
Environmental Services
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL DEVELOPMENT
10143 GROVE ROAD SOUTHEAST
THURSTON COUNTY (YELM),WASHINGTON
ES-9132
PREPARED FOR
COPPER RIDGE, LLC
May 9, 2023
_________________________
Brian C. Snow, G.I.T.
Senior Staff Geologist
_________________________
Scott S. Riegel, L.G., L.E.G.
Associate Principal Geologist
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL DEVELOPMENT
10143 GROVE ROAD SOUTHEAST
THURSTON COUNTY (YELM), WASHINGTON
ES-9132
Earth Solutions NW, LLC
15365 Northeast 90th Street, Suite 100
Redmond, Washington 98052
Phone: 425-449-4704 | Fax: 425-449-4711
www.earthsolutionsnw.com
05/09/2023
Geotechnical-Engineering Report
Important Information about This
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following information is provided to help.
The Geoprofessional Business Association (GBA)
has prepared this advisory to help you – assumedly
a client representative – interpret and apply this
geotechnical-engineering report as effectively as
possible. In that way, you can benefit from a lowered
exposure to problems associated with subsurface
conditions at project sites and development of
them that, for decades, have been a principal cause
of construction delays, cost overruns, claims,
and disputes. If you have questions or want more
information about any of the issues discussed herein,
contact your GBA-member geotechnical engineer.
Active engagement in GBA exposes geotechnical
engineers to a wide array of risk-confrontation
techniques that can be of genuine benefit for
everyone involved with a construction project.
Understand the Geotechnical-Engineering Services
Provided for this Report
Geotechnical-engineering services typically include the planning,
collection, interpretation, and analysis of exploratory data from
widely spaced borings and/or test pits. Field data are combined
with results from laboratory tests of soil and rock samples obtained
from field exploration (if applicable), observations made during site
reconnaissance, and historical information to form one or more models
of the expected subsurface conditions beneath the site. Local geology
and alterations of the site surface and subsurface by previous and
proposed construction are also important considerations. Geotechnical
engineers apply their engineering training, experience, and judgment
to adapt the requirements of the prospective project to the subsurface
model(s). Estimates are made of the subsurface conditions that
will likely be exposed during construction as well as the expected
performance of foundations and other structures being planned and/or
affected by construction activities.
The culmination of these geotechnical-engineering services is typically a
geotechnical-engineering report providing the data obtained, a discussion
of the subsurface model(s), the engineering and geologic engineering
assessments and analyses made, and the recommendations developed
to satisfy the given requirements of the project. These reports may be
titled investigations, explorations, studies, assessments, or evaluations.
Regardless of the title used, the geotechnical-engineering report is an
engineering interpretation of the subsurface conditions within the context
of the project and does not represent a close examination, systematic
inquiry, or thorough investigation of all site and subsurface conditions.
Geotechnical-Engineering Services are Performed
for Specific Purposes, Persons, and Projects,
and At Specific Times
Geotechnical engineers structure their services to meet the specific
needs, goals, and risk management preferences of their clients. A
geotechnical-engineering study conducted for a given civil engineer
will not likely meet the needs of a civil-works constructor or even a
different civil engineer. Because each geotechnical-engineering study
is unique, each geotechnical-engineering report is unique, prepared
solely for the client.
Likewise, geotechnical-engineering services are performed for a specific
project and purpose. For example, it is unlikely that a geotechnical-
engineering study for a refrigerated warehouse will be the same as
one prepared for a parking garage; and a few borings drilled during
a preliminary study to evaluate site feasibility will not be adequate to
develop geotechnical design recommendations for the project.
Do not rely on this report if your geotechnical engineer prepared it:
• for a different client;
• for a different project or purpose;
• for a different site (that may or may not include all or a portion of
the original site); or
• before important events occurred at the site or adjacent to it;
e.g., man-made events like construction or environmental
remediation, or natural events like floods, droughts, earthquakes,
or groundwater fluctuations.
Note, too, the reliability of a geotechnical-engineering report can
be affected by the passage of time, because of factors like changed
subsurface conditions; new or modified codes, standards, or
regulations; or new techniques or tools. If you are the least bit uncertain
about the continued reliability of this report, contact your geotechnical
engineer before applying the recommendations in it. A minor amount
of additional testing or analysis after the passage of time – if any is
required at all – could prevent major problems.
Read this Report in Full
Costly problems have occurred because those relying on a geotechnical-
engineering report did not read the report in its entirety. Do not rely on
an executive summary. Do not read selective elements only. Read and
refer to the report in full.
You Need to Inform Your Geotechnical Engineer
About Change
Your geotechnical engineer considered unique, project-specific factors
when developing the scope of study behind this report and developing
the confirmation-dependent recommendations the report conveys.
Typical changes that could erode the reliability of this report include
those that affect:
• the site’s size or shape;
• the elevation, configuration, location, orientation,
function or weight of the proposed structure and
the desired performance criteria;
• the composition of the design team; or
• project ownership.
As a general rule, always inform your geotechnical engineer of project
or site changes – even minor ones – and request an assessment of their
impact. The geotechnical engineer who prepared this report cannot accept
responsibility or liability for problems that arise because the geotechnical
engineer was not informed about developments the engineer otherwise
would have considered.
Most of the “Findings” Related in This Report
Are Professional Opinions
Before construction begins, geotechnical engineers explore a site’s
subsurface using various sampling and testing procedures. Geotechnical
engineers can observe actual subsurface conditions only at those specific
locations where sampling and testing is performed. The data derived from
that sampling and testing were reviewed by your geotechnical engineer,
who then applied professional judgement to form opinions about
subsurface conditions throughout the site. Actual sitewide-subsurface
conditions may differ – maybe significantly – from those indicated in
this report. Confront that risk by retaining your geotechnical engineer
to serve on the design team through project completion to obtain
informed guidance quickly, whenever needed.
This Report’s Recommendations Are
Confirmation-Dependent
The recommendations included in this report – including any options or
alternatives – are confirmation-dependent. In other words, they are not
final, because the geotechnical engineer who developed them relied heavily
on judgement and opinion to do so. Your geotechnical engineer can finalize
the recommendations only after observing actual subsurface conditions
exposed during construction. If through observation your geotechnical
engineer confirms that the conditions assumed to exist actually do exist,
the recommendations can be relied upon, assuming no other changes have
occurred. The geotechnical engineer who prepared this report cannot assume
responsibility or liability for confirmation-dependent recommendations if you
fail to retain that engineer to perform construction observation.
This Report Could Be Misinterpreted
Other design professionals’ misinterpretation of geotechnical-
engineering reports has resulted in costly problems. Confront that risk
by having your geotechnical engineer serve as a continuing member of
the design team, to:
• confer with other design-team members;
• help develop specifications;
• review pertinent elements of other design professionals’ plans and
specifications; and
• be available whenever geotechnical-engineering guidance is needed.
You should also confront the risk of constructors misinterpreting this
report. Do so by retaining your geotechnical engineer to participate in
prebid and preconstruction conferences and to perform construction-
phase observations.
Give Constructors a Complete Report and Guidance
Some owners and design professionals mistakenly believe they can shift
unanticipated-subsurface-conditions liability to constructors by limiting
the information they provide for bid preparation. To help prevent
the costly, contentious problems this practice has caused, include the
complete geotechnical-engineering report, along with any attachments
or appendices, with your contract documents, but be certain to note
conspicuously that you’ve included the material for information purposes
only. To avoid misunderstanding, you may also want to note that
“informational purposes” means constructors have no right to rely on
the interpretations, opinions, conclusions, or recommendations in the
report. Be certain that constructors know they may learn about specific
project requirements, including options selected from the report, only
from the design drawings and specifications. Remind constructors
that they may perform their own studies if they want to, and be sure to
allow enough time to permit them to do so. Only then might you be in
a position to give constructors the information available to you, while
requiring them to at least share some of the financial responsibilities
stemming from unanticipated conditions. Conducting prebid and
preconstruction conferences can also be valuable in this respect.
Read Responsibility Provisions Closely
Some client representatives, design professionals, and constructors do
not realize that geotechnical engineering is far less exact than other
engineering disciplines. This happens in part because soil and rock on
project sites are typically heterogeneous and not manufactured materials
with well-defined engineering properties like steel and concrete. That
lack of understanding has nurtured unrealistic expectations that have
resulted in disappointments, delays, cost overruns, claims, and disputes.
To confront that risk, geotechnical engineers commonly include
explanatory provisions in their reports. Sometimes labeled “limitations,”
many of these provisions indicate where geotechnical engineers’
responsibilities begin and end, to help others recognize their own
responsibilities and risks. Read these provisions closely. Ask questions.
Your geotechnical engineer should respond fully and frankly.
Geoenvironmental Concerns Are Not Covered
The personnel, equipment, and techniques used to perform an
environmental study – e.g., a “phase-one” or “phase-two” environmental
site assessment – differ significantly from those used to perform a
geotechnical-engineering study. For that reason, a geotechnical-engineering
report does not usually provide environmental findings, conclusions, or
recommendations; e.g., about the likelihood of encountering underground
storage tanks or regulated contaminants. Unanticipated subsurface
environmental problems have led to project failures. If you have not
obtained your own environmental information about the project site,
ask your geotechnical consultant for a recommendation on how to find
environmental risk-management guidance.
Obtain Professional Assistance to Deal with
Moisture Infiltration and Mold
While your geotechnical engineer may have addressed groundwater,
water infiltration, or similar issues in this report, the engineer’s
services were not designed, conducted, or intended to prevent
migration of moisture – including water vapor – from the soil
through building slabs and walls and into the building interior, where
it can cause mold growth and material-performance deficiencies.
Accordingly, proper implementation of the geotechnical engineer’s
recommendations will not of itself be sufficient to prevent
moisture infiltration. Confront the risk of moisture infiltration by
including building-envelope or mold specialists on the design team.
Geotechnical engineers are not building-envelope or mold specialists.
Copyright 2019 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly
prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of
GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind.
Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent or intentional (fraudulent) misrepresentation.
Telephone: 301/565-2733
e-mail: info@geoprofessional.org www.geoprofessional.org
May 9, 2023
ES-9132
Copper Ridge, LLC
P.O. Box 73790
Puyallup, Washington 98373
Attention: Mr. Evan Mann
Dear Mr. Mann:
Earth Solutions NW, LLC (ESNW) is pleased to present this report to support the proposed
development. Based on the results of our investigation, construction of the proposed residential
structures is feasible from a geotechnical standpoint. Subsurface exploration indicates the site
is underlain by native soils consisting primarily of poorly to well-graded gravel with sand and
variable amounts of silt (USCS: GP, GW, GP-GM, GW-GM). The native soils were chiefly
observed to be in a damp and dense condition extending to the termination depth of all test pits
advanced across the site. Moderate to severe caving was noted at all test locations due to the
cohesionless nature of the native soils.
In general, competent native soil suitable for support of foundations will likely be encountered
beginning at depths of about two feet below the existing ground surface across the site. The
proposed structures can be constructed on conventional continuous and spread foundations
supported on competent native soil, recompacted native soil, or new structural fill placed directly
on competent native soil.
The gravel dominant native soils exhibit excellent infiltration characteristics, and will likely be
feasible for full infiltration pending a seasonal groundwater monitoring study. A local groundwater
table was encountered across the site during the March 2023 exploration beginning at depths
between about 12 to 14 feet below existing grades, and although seasonally high groundwater
elevations typically peak in the late winter and early spring months, further characterization of
groundwater fluctuations will likely be necessary to satisfy Thurston County requirements.
Pertinent geotechnical recommendations for the proposed residential development are provided
in this report. We appreciate the opportunity to be of service to you on this project. Please call if
you have any questions or if we can be of further assistance.
Sincerely,
EARTH SOLUTIONS NW, LLC
Brian C. Snow, G.I.T.
Senior Staff Geologist
15365 N.E. 90th Street, Suite 100 • Redmond, WA 98052 •(425) 449-4704 • FAX (425) 449-4711
Earth Solutions NW LLC
Geotechnical Engineering, Construction
Observation/Testing and Environmental Services
Earth Solutions NW, LLC
Table of Contents
ES-9132
PAGE
INTRODUCTION ................................................................................. 1
General .................................................................................... 1
Project Description ................................................................. 2
SITE CONDITIONS ............................................................................. 2
Surface ..................................................................................... 2
Subsurface .............................................................................. 3
Topsoil and Fill ............................................................. 3
Native Soil ..................................................................... 3
Geologic Setting ........................................................... 3
Groundwater ................................................................. 4
GEOLOGIC HAZARD AREAS EVALUATION ................................... 4
DISCUSSION AND RECOMMENDATIONS ....................................... 5
General .................................................................................... 5
Site Preparation and Earthwork ............................................. 5
Temporary Erosion Control ......................................... 6
Stripping ....................................................................... 6
In-situ and Imported Soil ............................................. 6
Structural Fill ................................................................ 7
Excavations and Slopes .............................................. 7
Subgrade Preparation .................................................. 8
Void Space Restoration ............................................... 8
Foundations ............................................................................ 8
Retaining Walls ....................................................................... 9
Slab-on-Grade Floors ............................................................. 10
Drainage................................................................................... 10
Preliminary Infiltration Evaluation .............................. 10
Seismic Design ....................................................................... 11
Utility Support and Trench Backfill ....................................... 12
Preliminary Pavement Sections ............................................. 12
LIMITATIONS ...................................................................................... 13
Additional Services ................................................................. 13
Earth Solutions NW, LLC
Table of Contents
Cont’d
ES-9132
GRAPHICS
Plate 1 Vicinity Map
Plate 2 Test Pit Location Plan
Plate 3 Retaining Wall Drainage Detail
Plate 4 Footing Drain Detail
APPENDICES
Appendix A Subsurface Exploration
Test Pit Logs
Appendix B Laboratory Test Results
Earth Solutions NW, LLC
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL DEVELOPMENT
10143 GROVE ROAD SOUTHEAST
THURSTON COUNTY (YELM), WASHINGTON
ES-9132
INTRODUCTION
General
This geotechnical engineering study (study) was prepared for the proposed residential
development to be constructed on the west side of Grove Road Southeast, just north of the
intersection with Old Yelm-McKenna Road Southeast, in the Yelm area of unincorporated
Thurston County, Washington. To complete our scope of services, we performed the following:
Subsurface exploration to characterize the soil and groundwater conditions.
Preliminary infiltration evaluation based primarily on our field observations and laboratory
analyses, including an estimate of infiltration rates using the grain size analysis method.
Installation of three groundwater monitoring piezometers at select exploration locations.
Laboratory testing of representative soil samples collected on site.
Engineering analyses for the proposed residential development.
Preparation of this report.
The following documents and resources were reviewed as part of our report preparation:
Preliminary Site Plan, prepared by AHBL, Job No. 2230128.10, dated March 23, 2023.
Geologic Framework for the Puget Sound Aquifer System, Washington and British
Columbia, U.S. Geological Survey, Professional Paper 1424-C: Surficial Hydrogeologic
Units of the Puget Sound Aquifer System, Washington and British Columbia, for the
Centralia Quadrangle, by Jones, M.A., dated 1999.
Web Soil Survey (WSS) online resource, maintained by the Natural Resources
Conservation Service (NRCS) under the United States Department of Agriculture (USDA).
Soil Survey of Thurston County, Washington, prepared by Pringle, R.F., Soil Conservation
Service, Issued June 1990.
Copper Ridge, LLC ES-9132
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Earth Solutions NW, LLC
Liquefaction Susceptibility Map of Thurston County, Washington, Palmer, S. P. et al.,
dated September 2004.
Volcano Hazards from Mount Rainier, Washington, USGS Open-File Report 98-428, by
Hoblitt, R.P. et al., revised 1998.
Thurston County Drainage Design and Erosion Control Manual, June 2022 Edition,
prepared by Thurston County Water Resources Division, Department of Public Works.
Thurston County Code.
Project Description
The subject site is located off the west side of Grove Road Southeast, approximately 600 feet
north of the intersection with Old Yelm-McKenna Road Southeast, in the Yelm area of
unincorporated Thurston County, Washington.
Per the referenced site plan, the site will be developed with 24 new residential lots and associated
improvements. Designated open space / storm tracts are indicated on the site plans (also
illustrated on Plate 2) and, based on the subsurface conditions observed during the fieldwork, we
anticipate site stormwater will be managed primarily through infiltrative facilities in these areas.
At the time of report submission, specific building loads were not available for review; however,
based on our experience with similar developments, the proposed residential structures will likely
be two to three stories in height and constructed using relatively lightly loaded wood framing
supported on conventional foundations. Perimeter footing loads will likely be about 1 to 2 kips
per linear foot. Slab-on-grade loading is anticipated to be approximately 150 pounds per square
foot (psf).
If the above design assumptions are incorrect or change, ESNW should be contacted to review
the recommendations provided in this report. ESNW should review final designs to confirm that
appropriate geotechnical recommendations have been incorporated into the plans.
SITE CONDITIONS
Surface
The subject site is located on the west side of Grove Road Southeast, approximately 600 feet
north of the intersection with Old Yelm-McKenna Road Southeast, in the Yelm area of
unincorporated Thurston County, Washington. The site consists of a single tax parcel (Thurston
County Parcel No. 51540302700) and totals about five acres of land area. The approximate site
location is depicted on Plate 1 (Vicinity Map). The site is bordered to the north and south by
existing residential development, to the west by Fort Stevens Elementary School, and to the east
by Grove Road Southeast.
Copper Ridge, LLC ES-9132
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Earth Solutions NW, LLC
The site is currently developed with one single-family residence, outbuildings, and associated
improvements. The existing topography is relatively level with little to no discernable topographic
relief across the parcel. Vegetation consists primarily of field grasses, hedges, and landscaping
areas.
Subsurface
A representative of ESNW observed, logged, and sampled seven test pits at accessible locations
within the property boundaries on March 29, 2023, using a machine and operator provided by the
client. The test pits were completed to assess and classify the site soils and to characterize the
groundwater conditions within areas proposed for new development. The maximum exploration
depth was approximately 16 feet below the existing ground surface (bgs).
The approximate locations of the test pits are depicted on Plate 2 (Test Pit Location Plan). Please
refer to the test pit logs provided in Appendix A for a more detailed description of subsurface
conditions. Representative soil samples collected at our exploration locations were analyzed in
general accordance with Unified Soil Classification System (USCS) and USDA methods and
procedures.
Topsoil and Fill
Topsoil was generally encountered within the upper 18 to 24 inches of existing grades at the test
pit locations. Deeper or shallower pockets of topsoil may be encountered locally across the site.
Topsoil was characterized by its dark brown color, the presence of fine organic material, and
small root intrusions.
Fill was not encountered during our subsurface exploration. However, isolated areas of fill should
be expected surrounding the existing site improvements, including building foundations and utility
lines. If encountered, fill soils intended for reuse as structural fill should be primarily free of
organic and other deleterious material and should be evaluated for suitability by ESNW at the
time of construction.
Native Soil
Underlying the topsoil, native soils consisting primarily of poorly to well-graded gravel with sand
and variable amounts of silt (USCS: GP, GW, GP-GM, GW-GM). The native soils were chiefly
observed to be in a damp and dense condition and extended to the termination depth of all test
pits advanced across the site. Moderate to severe caving was noted at all test locations due to
the cohesionless nature of the native soils. Laboratory analyses of select samples indicates fines
content ranges between about two and eight percent.
Geologic Setting
Geologic mapping of the area identifies Vashon recessional outwash deposits of Pleistocene age
(Qvrg) as the primary geologic unit underlying the site. As reported on the geologic map resource,
the recessional outwash is described as moderately to poorly sorted gravel and sand with small
amounts of silt and clay, which include ice-contact deposits, glacial outwash alluvium, and small
amounts of ablation till.
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Earth Solutions NW, LLC
The online WSS resource identifies Spanaway gravelly and stony sandy loams as the primary
soil units underlying the site. The referenced soil survey characterizes Spanaway gravelly and
stony sandy loams with slow runoff and slight hazard of water erosion.
Based on the soil conditions encountered during our fieldwork, the native soils are representative
of recessional outwash deposits, consistent with the geologic and soils mapping resources
outlined in this section.
Groundwater
Groundwater was encountered in three of the seven test pits excavated, generally about 12 to
14 feet below existing surface grades, which is interpreted to represent the local table. It should
be noted that the remaining four test pits (where groundwater was not observed) were terminated
above the observed groundwater table elevation; given the observed subsurface geologic
conditions and our experience in the project vicinity, pervasive groundwater underlies the entire
project site and much of the surrounding region. The local groundwater table is likely subject to
seasonal fluctuations in elevation, and groundwater monitoring piezometers were installed at
three of the test pit locations (TP-1, -4, and -5) for future monitoring services, if requested.
Groundwater flow rates and elevations may fluctuate depending on many factors, including
precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater
flow rates are higher during the winter, spring, and early summer months. In any case,
groundwater conditions should be expected within deeper site excavations, particularly during
the wet season when groundwater elevations are likely to be higher. Depending on the timing,
depth, and extent of such excavations, temporary dewatering may be necessary.
GEOLOGIC HAZARD AREAS EVALUATION
ESNW reviewed Thurston County Code, Title 24 – Critical Areas, to evaluate the presence of
geologic hazard areas at the subject site. Geologic hazard areas in Thurston County include
those areas that because of their susceptibility to erosion, landsliding, earthquake, volcanic lahar,
liquefaction, or other geological events, are not suited to siting commercial, residential, or
industrial development consistent with public health or safety concerns.
Based on our review, the subject site does not contain geologic hazard areas as defined in
Thurston County Code. It is noted that the Nisqually River and associated floodplain, roughly
one mile east of the subject site, is a potential flow path for lahars originating on the flanks of Mt.
Rainier. However, the subject site is not located within an identified “lahar inundation zone” per
the referenced hazard mapping resources, and is therefore not located within a volcanic hazard
area.
Therefore, in our opinion, standard design elements may be used for this project.
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Earth Solutions NW, LLC
DISCUSSION AND RECOMMENDATIONS
General
Based on the results of our investigation, construction of the proposed residential structures is
feasible from a geotechnical standpoint. The primary geotechnical considerations associated
with the proposed project include foundation support, slab-on-grade support, and stormwater
facility installation and drainage.
Subsurface exploration indicates the site is underlain by native soils consisting primarily of poorly
to well-graded gravel with sand and variable amounts of silt (USCS: GP, GW, GP-GM, GW-GM).
The native soils were chiefly observed to be in a damp and dense condition extending to the
termination depth of all test pits advanced across the site. Moderate to severe caving was noted
at all test locations due to the cohesionless nature of the native soils.
In general, competent native soil suitable for support of foundations will likely be encountered
beginning at depths of about two feet below the existing ground surface across the site. The
proposed structures can be constructed on conventional continuous and spread foundations
supported on competent native soil, recompacted native soil, or new structural fill placed directly
on competent native soil.
The gravel dominant native soils exhibit excellent infiltration characteristics, and will likely be
feasible for full infiltration pending a seasonal groundwater monitoring study. A local groundwater
table was encountered across the site during the March 2023 exploration beginning at depths
between about 12 to 14 feet below existing grades, and although seasonally high groundwater
elevations typically peak in the late winter and early spring months, further characterization of
groundwater fluctuations will likely be necessary to satisfy Thurston County requirements.
This study has been prepared for the exclusive use of Copper Ridge, LLC, and its
representatives. No warranty, expressed or implied, is made. This study has been prepared in
a manner consistent with the level of care and skill ordinarily exercised by other members of the
profession currently practicing under similar conditions in this area.
Site Preparation and Earthwork
Site preparation activities should consist of installing temporary erosion control measures,
establishing grading limits, performing site stripping, and removing existing structural
improvements. Subsequent earthwork activities will likely include additional site grading, utility
installations, and associated site improvements.
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Temporary Erosion Control
The following temporary erosion and sediment control Best Management Practices (BMPs) are
recommended:
Temporary construction entrances and drive lanes, consisting of at least six inches of
quarry spalls, should be considered to both minimize off-site soil tracking and provide
stable surfaces at site entrances. Placing geotextile fabric underneath the quarry spalls
will provide greater stability if needed.
Silt fencing should be placed around the appropriate portions of the site perimeter to
prevent offsite migration of sediment.
When not in use, soil stockpiles should be covered or otherwise protected (as necessary)
to reduce the potential for soil erosion, especially during periods of wet weather.
As necessary, temporary measures for controlling surface water runoff, such as
interceptor trenches, sumps, or interceptor swales, should be installed prior to beginning
earthwork activities. For this site, infiltration may also be considered for control of surface
water runoff.
Dry soils disturbed during construction should be wetted to minimize dust and airborne soil
erosion.
Additional Best Management Practices, as specified by the project civil engineer and indicated
on the plans, should be incorporated into construction activities. Temporary erosion control
measures may be modified during construction as site conditions require, as approved by the site
erosion control lead.
Stripping
Topsoil was encountered within the upper 18 to 24 inches of existing grades across the site. The
organic-rich topsoil should be stripped (as necessary) and segregated into a stockpile for later
use on site or to haul off site. However, over-stripping should be avoided. As such, ESNW should
observe initial stripping activities to provide recommendations regarding the required stripping
depths and material suitability.
In-situ and Imported Soil
The in-situ soils encountered at the subject site have a low sensitivity to moisture and were
generally in a damp condition at the time of exploration. Soils anticipated to be exposed on site
will likely be too dry to attain adequate compaction and will require moisture conditioning through
the addition of water prior to use as structural fill. However, where encountered, soils that are
excessively over the optimum moisture content will likely require aeration or treatment prior to
placement and compaction. An ESNW representative should determine the suitability of in-situ
soils for use as structural fill at the time of construction.
Copper Ridge, LLC ES-9132
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Earth Solutions NW, LLC
Imported soil intended for use as structural fill should be evaluated by ESNW during construction.
The imported soil must be workable to the optimum moisture content, as determined by the
Modified Proctor Method (ASTM D1557), at the time of placement and compaction. During wet
weather conditions, imported soil intended for use as structural fill should consist of a well-graded,
granular soil with a fines content of 5 percent or less (where the fines content is defined as the
percent passing the Number 200 sieve, based on the minus three-quarter-inch fraction).
Structural Fill
Structural fill is defined as compacted soil placed in foundation, slab-on-grade, roadway,
permanent slope, retaining wall, and utility trench backfill areas. Structural fill placed and
compacted during site grading activities should meet the following specifications and guidelines:
Structural fill material Granular soil*
Moisture content At or slightly above optimum†
Relative compaction (minimum) 95 percent (Modified Proctor)‡
Loose lift thickness (maximum) 12 inches
* Existing gravel soils will likely require moisture conditioning (addition of water) prior to placement and compaction.
† Soil shall not be placed dry of optimum and should be evaluated by ESNW during construction.
‡ Minimum relative compaction of 90% may be feasible for mass grading activities and should be evaluated by
ESNW during construction.
With respect to underground utility installations and backfill, local jurisdictions may dictate the soil
type(s) and compaction requirements. Unsuitable material or debris must be removed from
structural areas if encountered.
Excavations and Slopes
Based on the soil conditions observed at the subsurface exploration locations, excavation
activities are likely to expose cohesionless native gravel soils beginning at depths of
approximately 18 to 24 inches below the existing ground surface. The native cohesionless
gravels are classified as Type C soils, and the following Federal Occupation Safety and Health
Administration and Washington Industrial Safety and Health Act soil classifications and maximum
allowable temporary slope inclinations may be used:
Areas exposing groundwater seepage 1.5H:1V (Type C)
Cohesionless native soil 1.5H:1V (Type C)
Permanent slopes should be planted with vegetation to both enhance stability and minimize
erosion and should maintain a gradient of 2H:1V or flatter. An ESNW representative should
observe temporary and permanent slopes to confirm the slope inclinations are suitable for the
exposed soil conditions and to provide additional excavation and slope recommendations as
necessary. If the recommended temporary slope inclinations cannot be achieved, temporary
shoring may be necessary to support excavations.
Copper Ridge, LLC ES-9132
May 9, 2023 Page 8
Earth Solutions NW, LLC
Subgrade Preparation
Foundations should be constructed on competent native soil or structural fill placed directly atop
competent native soil. Loose or unsuitable soil conditions encountered below areas of footing
and slab elements should be remedied as recommended in this report. In general, foundation
subgrades on native cut surfaces should be compacted in-situ to a minimum depth of one foot
below the design subgrade elevation. Uniform compaction of the foundation and slab subgrade
areas will establish a relatively consistent subgrade condition below the foundation and slab
elements. ESNW should observe the foundation and slab subgrade prior to placing formwork.
Supplementary recommendations for subgrade improvement can be provided at the time of
construction and would likely include further mechanical compaction effort and/or overexcavation
and replacement with suitable structural fill.
Void Space Restoration
The process of removing the existing structures may produce voids where old foundations are
removed and where crawl space areas may have been present. Complete restoration of voids
from old foundation areas must be executed as part of the subgrade preparation activities. The
following guidelines for preparing subgrade areas should be incorporated into the final design:
Where voids and related demolition disturbances extend below planned subgrade
elevations, restoration of these areas should be completed. Structural fill should be used
to restore voids or unstable areas resulting from the removal of existing structural
elements.
Recompact, or overexcavate and replace, areas of existing fill exposed at the design
subgrade elevations. Overexcavations should extend into competent native soils and
structural fill should be utilized to restore subgrade elevations as necessary.
ESNW should confirm subgrade conditions, as well as the required level of recompaction
and/or overexcavation and replacement, during site preparation activities. ESNW should
also evaluate the overall suitability of prepared subgrade areas following site preparation
activities.
Foundations
The proposed structures can be constructed on conventional continuous and spread footing
foundations bearing on competent native soil, recompacted native soil, or new structural fill
placed directly on competent native soil. Provided site earthwork activities are completed in
accordance with our recommendations, suitable soil conditions should be exposed at foundation
subgrade elevations.
Where loose or unsuitable soil conditions are encountered at foundation subgrade elevations,
compaction of the soils to the specifications of structural fill, or overexcavation and replacement
with suitable structural fill will likely be necessary. A representative of ESNW should confirm
suitability of foundation subgrades at the time of construction. If deemed necessary, the
undisturbed weathered native soils may be compacted in-situ provided the soil is at or slightly
above the optimum moisture content.
Copper Ridge, LLC ES-9132
May 9, 2023 Page 9
Earth Solutions NW, LLC
Provided the structures will be supported as described above, the following parameters may be
used for design of the new foundations:
Allowable soil bearing capacity 2,500 psf
Passive earth pressure 300 pcf
Coefficient of friction 0.40
A one-third increase in the allowable soil bearing capacity can be assumed for short-term wind
and seismic loading conditions. The passive earth pressure and coefficient of friction values
include a safety factor of 1.5. With structural loading as expected, total settlement in the range
of one inch is anticipated, with differential settlement of about one-half inch. The majority of the
settlement should occur during construction as dead loads are applied.
Retaining Walls
Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The
following parameters may be used for retaining wall design:
Active earth pressure (unrestrained condition) 35 pcf
At-rest earth pressure (restrained condition) 55 pcf
Traffic surcharge (passenger vehicles) 70 psf (rectangular distribution)
Passive earth pressure 300 pcf
Coefficient of friction 0.40
Seismic surcharge 8H psf*
* Where H equals the retained height (in feet).
The passive earth pressure and coefficient of friction values include a safety factor of 1.5.
Additional surcharge loading from adjacent foundations, sloped backfill, or other loads should be
included in the retaining wall design.
Retaining walls should be backfilled with free-draining material that extends along the height of
the wall and a distance of at least 18 inches behind the wall. The upper 12 inches of the wall
backfill may consist of a less permeable soil, if desired.
Drainage should be provided behind retaining walls such that hydrostatic pressures do not
develop. If drainage is not provided, hydrostatic pressures should be included in the wall design.
A perforated drainpipe should be placed along the base of the wall and connected to an approved
discharge location. A typical retaining wall drainage detail is provided on Plate 3.
Copper Ridge, LLC ES-9132
May 9, 2023 Page 10
Earth Solutions NW, LLC
Slab-on-Grade Floors
Slab-on-grade floors should be supported on a firm and unyielding subgrade consisting of
competent native soil or at least 12 inches of new structural fill. Unstable or yielding areas of the
subgrade should be recompacted or overexcavated and replaced with suitable structural fill prior
to slab construction.
Where free-draining native gravel soils are not exposed at the subgrade, a capillary break
consisting of a minimum of four inches of free-draining crushed rock or gravel should be placed
below the slab. The free-draining material should have a fines content of 5 percent or less defined
as the percent passing the number 200 sieve, based on the minus three-quarters-inch fraction.
In areas where slab moisture is undesirable, installation of a vapor barrier below the slab should
be considered. If used, the vapor barrier should consist of a material specifically designed to
function as a vapor barrier and should be installed in accordance with the manufacturer’s
specifications.
Drainage
Finish grades must be designed to direct surface drain water away from structures and slopes.
Water must not be allowed to pond adjacent to structures or slopes. For preliminary planning
purposes installation of a foundation drain should be considered for the building perimeter
footings (a typical foundation drain detail is provided on Plate 4). However, due to the porous
nature of the native gravel deposits, eliminating the footing drain at some locations may be
feasible. In any case, the geotechnical engineer should be consulted to evaluate further the need
for footing drain applications at the time of foundation construction.
Preliminary Infiltration Evaluation
As indicated in the Subsurface section of this study, native soils encountered during our fieldwork
were characterized primarily as recessional outwash gravel deposits. The relatively clean gravels
observed in the project area exhibit favorable infiltration characteristics and will likely be feasible
for full infiltration, provided adequate separation from the local seasonal high groundwater level
is maintained. Groundwater mounding analyses may also be prudent depending on seasonal
groundwater fluctuations related to infiltration system design elevations.
Per Volume III – Appendix III-A of the June 2022 Thurston County Drainage and Erosion Control
Manual (Manual), we estimated design infiltration rates for select locations and depths using the
soil grain size analysis method (Method 3). The calculation parameters and results are provided
below:
Test Pit
ID
Sample
Depth
D10 D60 D90 f fines F testing F geometry F plugging I design
TP-1 12 ft 0.51 19.363 31.788 3.0% 0.40 1.0 1.0 92.75
TP-3 5 ft 0.385 15.069 30.258 7.4% 0.40 1.0 0.7 27.47
TP-3 10 ft 0.186 12.708 28.728 7.6% 0.40 1.0 0.7 10.99
TP-5 5 ft 0.73 27.021 61.967 3.1% 0.40 1.0 1.0 127.58
TP-7 11 ft 0.936 17.88 31.402 2.3% 0.40 1.0 1.0 594.38
Copper Ridge, LLC ES-9132
May 9, 2023 Page 11
Earth Solutions NW, LLC
Where D10, D60, and D90 are the grain sizes in mm for which 10 percent, 60 percent, and 90
percent of the sample is more-fine, ffines is the fraction of soil (by weight) that passes the number-
200 sieve, F testing, F geometry, and F plugging are mandatory correction factors prescribed by the
manual, and Idesign is the design infiltration rate reported in inches per hour.
Given the preliminary stage of project design, the value for Fgeometry was assumed at 1.0.
However, the value for Fgeometry is controlled by the proposed infiltration facility’s design, including
both facility width (W) and depth to the water table or impervious strata (D). The value of Fgeometry
must be between 0.25 and 1.0, and should be reevaluated as stormwater designs progress.
Based on the observed geologic conditions and the preliminary calculations outlined above, we
anticipate the maximum allowable design infiltration rate in Thurston County (30 inches per hour)
will generally be suitable for the proposed infiltration facilities. Per the Manual, in no circumstance
shall new infiltration facilities be designed with rates exceeding 30 inches per hour.
The values for Idesign provided above should be considered preliminary and should be reviewed
by ESNW as project plans develop, finalized facility geometries become available, and seasonal
groundwater fluctuations are further characterized.
Seismic Design
The 2018 International Building Code (2018 IBC) recognizes the most recent edition of the
Minimum Design Loads for Buildings and Other Structures manual (ASCE 7-16) for seismic
design, specifically with respect to earthquake loads. Based on the soil conditions encountered
at the test pit locations, the parameters and values provided below are recommended for seismic
design per the 2018 IBC.
Parameter Value
Site Class D*
Mapped short period spectral response acceleration, SS (g) 1.282
Mapped 1-second period spectral response acceleration, S1 (g) 0.462
Short period site coefficient, Fa 1
Long period site coefficient, Fv 1.838†
Adjusted short period spectral response acceleration, SMS (g) 1.282
Adjusted 1-second period spectral response acceleration, SM1 (g) 0.849†
Design short period spectral response acceleration, SDS (g) 0.855
Design 1-second period spectral response acceleration, SD1 (g) 0.566†
* Assumes dense native soil conditions, encountered to a maximum depth of 16 feet bgs during the March 2023
field exploration, remain dense to at least 100 feet bgs. Based on our experience with the project geologic setting
(recessional outwash), soil conditions are likely consistent with this assumption.
† Values assume Fv may be determined using linear interpolation per Table 11.4-2 in ASCE 7-16.
Copper Ridge, LLC ES-9132
May 9, 2023 Page 12
Earth Solutions NW, LLC
As indicated in the table footnote, several of the seismic design values provided above are
dependent on the assumption that site-specific ground motion analysis (per Section 11.4.8 of
ASCE 7-16) will not be required for the subject project. ESNW recommends the validity of this
assumption be confirmed at the earliest available opportunity during the planning and early
design stages of the project. Further discussion between the project structural engineer, the
project owner, and ESNW may be prudent to determine the possible impacts to the structural
design due to increased earthquake load requirements under the 2018 IBC. ESNW can provide
additional consulting services to aid with design efforts, including supplementary geotechnical
and geophysical investigation, upon request.
Liquefaction is a phenomenon that can occur within a soil profile as a result of an intense ground
shaking or loading condition. Most commonly, liquefaction is caused by ground shaking during
an earthquake. Soil profiles that are loose, cohesionless, and present below the groundwater
table are most susceptible to liquefaction. During the ground shaking, the soil contracts, and
porewater pressure increases. The increased porewater pressure occurs quickly and without
sufficient time to dissipate, resulting in water flowing upward to the ground surface and a liquefied
soil condition. Soil in a liquefied condition possesses very little shear strength in comparison to
the drained condition, which can result in a loss of foundation support for structures.
The referenced liquefaction susceptibility map indicates the site maintains a very low
susceptibility to liquefaction. In our opinion, site susceptibility to liquefaction may be considered
very low to negligible. The relatively dense, gravel dominant, and clast supported native soil
deposits observed across the site exhibit very low susceptibility to liquefaction, and were the
primary bases for this opinion.
Utility Support and Trench Backfill
In our opinion, the on-site soil will generally be suitable for support of utilities. Use of the native
soil as structural backfill in the utility trench excavations will depend on the in-situ moisture
content at the time of placement and compaction. If native soil is placed below the optimum
moisture content, settlement will likely occur once wet weather impacts the trenches. As such,
backfill soils should be properly moisture conditioned, as necessary, to ensure acceptability of
the soil moisture content at the time of placement and compaction. Utility trench backfill should
be placed and compacted to the specifications of structural fill provided in this report or to the
applicable requirements of the presiding jurisdiction. Due to the presence of gravel outwash soils,
particles larger than six inches in size should be removed from utility trench native backfill
material.
Preliminary Pavement Sections
The performance of site pavements is largely related to the condition of the underlying subgrade.
To ensure adequate pavement performance, the subgrade should be in a firm and unyielding
condition when subjected to proof rolling with a loaded dump truck. Structural fill in pavement
areas should be compacted to the specifications previously detailed in this report. Soft, wet, or
otherwise unsuitable or yielding subgrade conditions will require remedial measures, such as
overexcavation and/or placement of thick crushed rock or structural fill sections, prior to
pavement.
Copper Ridge, LLC ES-9132
May 9, 2023 Page 13
Earth Solutions NW, LLC
We anticipate new pavement sections will be subjected primarily to passenger vehicle traffic. For
lightly loaded pavement areas subjected primarily to passenger vehicles, the following
preliminary pavement sections may be considered:
A minimum of two inches of hot-mix asphalt (HMA) placed over four inches of crushed
rock base (CRB), or;
A minimum of two inches of HMA placed over three inches of asphalt-treated base (ATB).
Heavier traffic areas generally require thicker pavement sections depending on site usage,
pavement life expectancy, and site traffic. For preliminary design purposes, the following
pavement sections for occasional truck traffic and access roadways may be considered:
Three inches of HMA placed over six inches of CRB, or;
Three inches of HMA placed over four and one-half inches of ATB.
A representative of ESNW should be requested to observe subgrade conditions prior to
placement of CRB or ATB. As necessary, supplemental recommendations for achieving
subgrade stability and drainage can be provided. If on-site roads will be constructed with an
inverted crown, additional drainage measures may be recommended to assist in maintaining road
subgrade and pavement stability.
Final pavement design recommendations, including recommendations for heavy traffic areas,
access roads, and frontage improvement areas, can be provided once final traffic loading has
been determined. Road standards utilized by the governing jurisdiction may supersede the
recommendations provided in this report. The HMA, ATB, and CRB materials should conform to
WSDOT specifications. All soil base material should be compacted to a relative compaction of
95 percent, based on the laboratory maximum dry density as determined by ASTM D1557.
LIMITATIONS
This study has been prepared for the exclusive use of Copper Ridge, LLC, and its
representatives. The recommendations and conclusions provided in this study are professional
opinions consistent with the level of care and skill that is typical of other members in the
profession currently practicing under similar conditions in this area. A warranty is not expressed
or implied. Variations in the soil and groundwater conditions observed at the test pit locations
may exist and may not become evident until construction. ESNW should reevaluate the
conclusions provided in this study if variations are encountered.
Additional Services
ESNW should have an opportunity to review final project plans with respect to the geotechnical
recommendations provided in this report. ESNW should also be retained to provide testing and
consultation services as needed during design and construction phases of the project.
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drawn MRS
Checked SSR Date April 2023
Date 04/26/2023 Proj.No.9132
Plate 1
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
Vicinity Map
10143 Grove Road S.E.Property
Thurston County (Yelm),Washington
Reference:
Thurston County,Washington
OpenStreetMap.org
NORTH
NOTE:This plate may contain areas of color.ESNW cannot be
responsible for any subsequent misinterpretation of the information
resulting from black &white reproductions of this plate.
SITEYelm
Plate
Proj.No.
Date
Checked
DrawnEarthSolutionsNWLLC GeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCNORTH
NOTE:This plate may contain areas of color.ESNW cannot be
responsible for any subsequent misinterpretation of the information
resulting from black &white reproductions of this plate.
NOTE:The graphics shown on this plate are not intended for design
purposes or precise scale measurements,but only to illustrate the
approximate test locations relative to the approximate locations of
existing and /or proposed site features.The information illustrated
is largely based on data provided by the client at the time of our
study.ESNW cannot be responsible for subsequent design changes
or interpretation of the data by others.
LEGEND
Approximate Location of
ESNW Test Pit,Proj.No.
ES-9132,Mar.2023
Subject Site
Existing Building
0 5 0 1 0 0 2 0 0
Sc ale in Feet1"=1 0 0 'TestPitLocationPlan10143GroveRoadS.E.PropertyThurstonCounty(Yelm),WashingtonMRS
SSR
05/09/2023
9132
2
TP-1
TP-1
TP-2
TP-3
TP-4
TP-5
TP-6
TP-7
GROVE ROAD S.EOpen Space/
Park/Storm
Open Space/
Park/Storm
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drawn MRS
Checked SSR Date April 2023
Date 04/26/2023 Proj.No.9132
Plate 3
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
NOTES:
Free-draining Backfill should consist
of soil having less than 5 percent fines.
Percent passing No.4 sieve should be
25 to 75 percent.
Sheet Drain may be feasible in lieu
of Free-draining Backfill,per ESNW
recommendations.
Drain Pipe should consist of perforated,
rigid PVC Pipe surrounded with 1-inch
Drain Rock.
LEGEND:
Free-draining Structural Backfill
1-inch Drain Rock
18"Min.
Structural
Fill
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
SCHEMATIC ONLY -NOT TO SCALE
NOT A CONSTRUCTION DRAW ING
Retaining Wall Drainage Detail
10143 Grove Road S.E.Property
Thurston County (Yelm),Washington
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drawn MRS
Checked SSR Date April 2023
Date 04/26/2023 Proj.No.9132
Plate 4
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
Slope
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
18"Min.
NOTES:
Do NOT tie roof downspouts
to Footing Drain.
Surface Seal to consist of
12"of less permeable,suitable
soil.Slope away from building.
LEGEND:
Surface Seal:native soil or
other low-permeability material.
1-inch Drain Rock
SCHEMATIC ONLY -NOT TO SCALE
NOT A CONSTRUCTION DRAW ING
Footing Drain Detail
10143 Grove Road S.E.Property
Thurston County (Yelm),Washington
Earth Solutions NW, LLC
Appendix A
Subsurface Exploration
Test Pit Logs
ES-9132
Subsurface conditions on site were explored on March 29, 2023 by excavating seven test pits
using a machine and operator provided by the client. The approximate locations of the test pits
are illustrated on Plate 2 of this study. The subsurface exploration logs are provided in this
Appendix. The test pits were advanced to a maximum depth of about 16 feet bgs.
The final logs represent the interpretations of the field logs and the results of laboratory analyses.
The stratification lines on the logs represent the approximate boundaries between soil types. In
actuality, the transitions may be more gradual.
>12%Fines<5%FinesHighlyOrganicSoilsSiltsandClaysLiquidLimit50orMoreSiltsandClaysLiquidLimitLessThan50Fine-GrainedSoils-50%orMorePassesNo.200SieveCoarse-GrainedSoils-MoreThan50%RetainedonNo.200SieveSands-50%orMoreofCoarseFractionPassesNo.4SieveGravels-MoreThan50%ofCoarseFractionRetainedonNo.4Sieve>12%Fines<5%FinesGW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
MH
CH
OH
PT
Well-graded gravel with
or without sand,little to
no fines
Poorly graded gravel with
or without sand,little to
no fines
Silty gravel with or without
sand
Clayey gravel with or
without sand
Well-graded sand with
or without gravel,little to
no fines
Poorly graded sand with
or without gravel,little to
no fines
Silty sand with or without
gravel
Clayey sand with or
without gravel
Silt with or without sand
or gravel;sandy or
gravelly silt
Clay of low to medium
plasticity;lean clay with
or without sand or gravel;
sandy or gravelly lean clay
Organic clay or silt of
low plasticity
Elastic silt with or without
sand or gravel;sandy or
gravelly elastic silt
Clay of high plasticity;
fat clay with or without
sand or gravel;sandy or
gravelly fat clay
Organic clay or silt of
medium to high plasticity
Peat,muck,and other
highly organic soils
EEaarrtthh SSoolluuttiioonnss NNWW LLC
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
EXPLORATION LOG KEYFillFILLMadeGround
Classifications of soils in this geotechnical report and as shown on the exploration logs are based on visual
field and/or laboratory observations,which include density/consistency,moisture condition,grain size,and
plasticity estimates,and should not be construed to imply field or laboratory testing unless presented herein.
Visual-manual and/or laboratory classification methods of ASTM D2487 and D2488 were used as an
identification guide for the Unified Soil Classification System.
Terms Describing Relative Density and Consistency
Coarse-Grained Soils:
Fine-Grained Soils:
SPT blows/foot
SPT blows/foot
Test Symbols &Units
Fines =Fines Content (%)
MC =Moisture Content (%)
DD =Dry Density (pcf)
Str =Shear Strength (tsf)
PID =Photoionization Detector (ppm)
OC =Organic Content (%)
CEC =Cation Exchange Capacity (meq/100 g)
LL =Liquid Limit (%)
PL =Plastic Limit (%)
PI =Plasticity Index (%)
Component Definitions
Descriptive Term Size Range and Sieve Number
Smaller than No.200 (0.075 mm)
Boulders
Modifier Definitions
Percentage by
Weight (Approx.)
<5
5 to 14
15 to 29
>30_
Modifier
Trace (sand,silt,clay,gravel)
Slightly (sandy,silty,clayey,gravelly)
Sandy,silty,clayey,gravelly
Very (sandy,silty,clayey,gravelly)
Moisture Content
Dry -Absence of moisture,dusty,dry to
the touch
Damp -Perceptible moisture,likely below
optimum MC
Moist -Damp but no visible water,likely
at/near optimum MC
Wet -Water visible but not free draining,
likely above optimum MC
Saturated/Water Bearing -Visible free
water,typically below groundwater table
Symbols
Cement grout
surface seal
Bentonite
chips
Grout
seal
Filter pack with
blank casing
section
Screened casing
or Hydrotip with
filter pack
End cap
ATD =At time
of drilling
Static water
level (date)
_>50
Density
Very Loose
Loose
Medium Dense
Dense
Very Dense
Consistency
Very Soft
Soft
Medium Stiff
Stiff
Very Stiff
Hard
<4
4 to 9
10 to 29
30 to 49
<2
2 to 3
4 to 7
8 to 14
15 to 29
_>30
EEaarrtthh
NNWWLLC
EarthSolutions
NW LLC
Cobbles
Gravel
Coarse Gravel
Fine Gravel
Sand
Coarse Sand
Medium Sand
Fine Sand
Silt and Clay
Larger than 12"
3"to 12"
3"to No.4 (4.75 mm)
3"to 3/4"
3/4"to No.4 (4.75 mm)
No.4 (4.75 mm)to No.200 (0.075 mm)
No.4 (4.75 mm)to No.10 (2.00 mm)
No.10 (2.00 mm)to No.40 (0.425 mm)
No.40 (0.425 mm)to No.200 (0.075 mm)
338.5
325.0
MC = 4.0
MC = 5.7
Fines = 3.0
MC = 7.4
TPSL
GP
Dark brown TOPSOIL
-few gravels
Brown poorly graded GRAVEL with sand, dense, damp
-many cobbles
-scattered boulders
-severe caving TOH to BOH
[USDA Classification: extremely gravelly coarse SAND]
-groundwater table at time of digging
Test pit terminated at 15.0 feet below existing grade. No groundwater table encountered
at 14.0 feet during excavation. Caving observed from TOH to BOH.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not
surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for a
complete understanding of subsurface conditions.
1.5
15.0SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
PAGE 1 OF 1
TEST PIT NUMBER TP-1
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 3/29/23 COMPLETED 3/29/23
GROUND WATER LEVEL:
GROUND ELEVATION 340 ft
LATITUDE 46.93978 LONGITUDE -122.58597
LOGGED BY BCS CHECKED BY SSR
NOTES
SURFACE CONDITIONS Pasture grass
AT TIME OF EXCAVATION 14 ftAT TIME OF EXCAVATION 14 ft
AFTER EXCAVATION
PROJECT NUMBER ES-9132 PROJECT NAME 10143 Grove Road S.E. Property
GENERAL BH / TP / WELL - 9132.GPJ - GINT US.GDT - 5/9/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
338.0
331.0
MC = 6.6
MC = 4.1
TPSL
GW
Dark brown TOPSOIL
-scattered gravel
Brown well-graded GRAVEL with sand, dense, damp
-abundant cobbles
-scattered boulders
-severe caving to TOH to BOH
Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during
excavation. Caving observed from TOH to BOH.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not
surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for a
complete understanding of subsurface conditions.
2.0
9.0SAMPLE TYPENUMBERDEPTH(ft)0
5
PAGE 1 OF 1
TEST PIT NUMBER TP-2
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 3/29/23 COMPLETED 3/29/23
GROUND WATER LEVEL:
GROUND ELEVATION 340 ft
LATITUDE 46.93983 LONGITUDE -122.58656
LOGGED BY BCS CHECKED BY SSR
NOTES
SURFACE CONDITIONS Pasture grass
AT TIME OF EXCAVATIONAT TIME OF EXCAVATION
AFTER EXCAVATION
PROJECT NUMBER ES-9132 PROJECT NAME 10143 Grove Road S.E. Property
GENERAL BH / TP / WELL - 9132.GPJ - GINT US.GDT - 5/9/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
338.0
335.0
332.0
330.0
MC = 5.8
Fines = 7.4
MC = 6.5
Fines = 7.6
TPSL
GW
GP-
GM
GW-
GM
Dark brown TOPSOIL
-scattered gravel
Brown well-graded GRAVEL with sand, dense, damp
-abundant cobbles, scattered boulders
Brown poorly graded GRAVEL with silt and sand, dense, damp
[USDA Classification: extremely gravelly coarse sandy LOAM]
-moderate to severe caving from TOH to BOH
Brown well-graded GRAVEL with silt and sand, dense, damp
[USDA Classification: extremely gravelly coarse sandy LOAM]
Test pit terminated at 10.0 feet below existing grade. No groundwater encountered during
excavation. Caving observed from TOH to BOH.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not
surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for a
complete understanding of subsurface conditions.
2.0
5.0
8.0
10.0SAMPLE TYPENUMBERDEPTH(ft)0
5
10
PAGE 1 OF 1
TEST PIT NUMBER TP-3
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 3/29/23 COMPLETED 3/29/23
GROUND WATER LEVEL:
GROUND ELEVATION 340 ft
LATITUDE 46.94022 LONGITUDE -122.58624
LOGGED BY BCS CHECKED BY SSR
NOTES
SURFACE CONDITIONS Pasture grass
AT TIME OF EXCAVATIONAT TIME OF EXCAVATION
AFTER EXCAVATION
PROJECT NUMBER ES-9132 PROJECT NAME 10143 Grove Road S.E. Property
GENERAL BH / TP / WELL - 9132.GPJ - GINT US.GDT - 5/9/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
338.0
325.0
MC = 6.6
MC = 5.6
TPSL
GW
Dark brown TOPSOIL
-scattered gravel
Brown well-graded GRAVEL with sand, dense, moist
-abundant cobbles, scattered boulders
-severe caving from TOH to BOH
-groundwater table
Test pit terminated at 15.0 feet below existing grade. Groundwater table encountered at
12.5 feet during excavation. Caving observed from TOH to BOH.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not
surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for a
complete understanding of subsurface conditions.
2.0
15.0SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
PAGE 1 OF 1
TEST PIT NUMBER TP-4
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 3/29/23 COMPLETED 3/29/23
GROUND WATER LEVEL:
GROUND ELEVATION 340 ft
LATITUDE 46.94038 LONGITUDE -122.58632
LOGGED BY BCS CHECKED BY SSR
NOTES
SURFACE CONDITIONS Pasture grass
AT TIME OF EXCAVATION 12.5 ftAT TIME OF EXCAVATION 12.5 ft
AFTER EXCAVATION
PROJECT NUMBER ES-9132 PROJECT NAME 10143 Grove Road S.E. Property
GENERAL BH / TP / WELL - 9132.GPJ - GINT US.GDT - 5/9/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
338.0
324.0
MC = 4.1
Fines = 3.1
TPSL
GW
Dark brown TOPSOIL
-scattered gravel
Brown well-graded GRAVEL with sand, dense, damp
-abundant cobbles
-scattered boulders
[USDA Classification: extremely gravelly loamy coarse SAND]
-moderate to severe caving from TOH to BOH
-groundwater table
Test pit terminated at 16.0 feet below existing grade. Groundwater table encountered at
12.5 feet during excavation. Caving observed from TOM to BOH.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not
surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for a
complete understanding of subsurface conditions.
2.0
16.0SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
PAGE 1 OF 1
TEST PIT NUMBER TP-5
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 3/29/23 COMPLETED 3/29/23
GROUND WATER LEVEL:
GROUND ELEVATION 340 ft
LATITUDE 46.94032 LONGITUDE -122.58554
LOGGED BY BCS CHECKED BY SSR
NOTES
SURFACE CONDITIONS Pasture grass
AT TIME OF EXCAVATION 12.5 ftAT TIME OF EXCAVATION 12.5 ft
AFTER EXCAVATION
PROJECT NUMBER ES-9132 PROJECT NAME 10143 Grove Road S.E. Property
GENERAL BH / TP / WELL - 9132.GPJ - GINT US.GDT - 5/9/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
338.5
330.0
MC = 7.0
MC = 5.4
TPSL
GW
Dark brown TOPSOIL
-scattered gravel
Brown well-graded GRAVEL with sand, dense, damp
-abundant cobbles
-scattered boulders
-moderate to severe caving from TOH to BOH
Test pit terminated at 10.0 feet below existing grade. No groundwater encountered during
excavation. Caving observed from TOH to BOH.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not
surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for a
complete understanding of subsurface conditions.
1.5
10.0SAMPLE TYPENUMBERDEPTH(ft)0
5
10
PAGE 1 OF 1
TEST PIT NUMBER TP-6
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 3/29/23 COMPLETED 3/29/23
GROUND WATER LEVEL:
GROUND ELEVATION 340 ft
LATITUDE 46.94079 LONGITUDE -122.58569
LOGGED BY BCS CHECKED BY SSR
NOTES
SURFACE CONDITIONS Pasture grass
AT TIME OF EXCAVATIONAT TIME OF EXCAVATION
AFTER EXCAVATION
PROJECT NUMBER ES-9132 PROJECT NAME 10143 Grove Road S.E. Property
GENERAL BH / TP / WELL - 9132.GPJ - GINT US.GDT - 5/9/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
338.0
329.0
MC = 5.7
MC = 4.5
Fines = 2.3
TPSL
GW
Dark brown TOPSOIL
-scattered gravel
Brown well-graded GRAVEL with sand, dense, damp
-abundant cobbles
-scattered boulders
-moderate to severe caving from TOH to BOH
-increasing moisture content - likely capillary fringe
[USDA Classification: extremely gravelly coarse SAND]
Test pit terminated at 11.0 feet below existing grade. No groundwater encountered during
excavation. Caving observed from TOH to BOH.
LIMITATIONS: Ground elevation (if listed) is approximate; the test location was not
surveyed. Coordinates are approximate and based on the WGS84 datum. Do not rely on
this test log as a standalone document. Refer to the text of the geotechnical report for a
complete understanding of subsurface conditions.
2.0
11.0SAMPLE TYPENUMBERDEPTH(ft)0
5
10
PAGE 1 OF 1
TEST PIT NUMBER TP-7
EXCAVATION CONTRACTOR Client Provided
DATE STARTED 3/29/23 COMPLETED 3/29/23
GROUND WATER LEVEL:
GROUND ELEVATION 340 ft
LATITUDE 46.94072 LONGITUDE -122.58674
LOGGED BY BCS CHECKED BY SSR
NOTES
SURFACE CONDITIONS Pasture grass
AT TIME OF EXCAVATIONAT TIME OF EXCAVATION
AFTER EXCAVATION
PROJECT NUMBER ES-9132 PROJECT NAME 10143 Grove Road S.E. Property
GENERAL BH / TP / WELL - 9132.GPJ - GINT US.GDT - 5/9/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
Earth Solutions NW, LLC
Appendix B
Laboratory Test Results
ES-9132
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
3
D100
140
Specimen Identification
1
fine
6
HYDROMETER
304
3.0
7.4
7.6
3.1
2.3
101/2
COBBLES
Specimen Identification
4
coarse
20 401.5 8 14
USDA: Brown Extremely Gravelly Coarse Sand. USCS: GP with Sand.
USDA: Brown Extremely Gravelly Coarse Sandy Loam. USCS: GP-GM with Sand.
USDA: Brown Extremely Gravelly Coarse Sandy Loam. USCS: GW-GM with Sand.
USDA: Brown Extremely Gravelly Loamy Coarse Sand. USCS: GW with Sand.
USDA: Brown Extremely Gravelly Coarse Sand. USCS: GW with Sand.
6 60
PERCENT FINER BY WEIGHTD10
1.877
5.588
2.662
5.464
5.1
19.363
15.069
12.708
27.021
17.88
GRAIN SIZE DISTRIBUTION
100
37.98
39.12
68.29
37.01
19.10
LL
TP-01
TP-03
TP-03
TP-05
TP-07
0.51
0.385
0.186
0.73
0.936
3/4
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
GRAVEL SAND
37.5
37.5
37.5
75
37.5
%Silt
0.36
5.38
3.00
1.51
1.55
TP-01
TP-03
TP-03
TP-05
TP-07
2 2003
Cc CuClassification
%Clay
16
PID60 D30
coarse SILT OR CLAYfinemedium
GRAIN SIZE IN MILLIMETERS
3/8 50
12.0ft.
5.0ft.
10.0ft.
5.0ft.
11.0ft.
12.00ft.
5.00ft.
10.00ft.
5.00ft.
11.00ft.
PL
PROJECT NUMBER ES-9132 PROJECT NAME 10143 Grove Road S.E. Property
GRAIN SIZE USDA ES-9132 10143 GROVE ROAD S.E. PROPERTY.GPJ GINT US LAB.GDT 4/7/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
Earth Solutions NW, LLC
Report Distribution
ES-9132
EMAIL ONLY Copper Ridge, LLC
P.O. Box 73790
Puyallup, Washington 98373
Attention: Mr. Evan Mann