HomeMy WebLinkAboutRS_Geotechincal_Report_230825_v1EarthSolutionsNWLLC
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
TALBOT ROAD PROPERTY
2103 TALBOT ROAD SOUTH
RENTON,WASHINGTON
ES-9099
PREPARED FOR
SEATTLE LLL, LLC
July 18, 2023
_________________________
Brian C. Snow, L.G.
Senior Staff Geologist
_________________________
Henry T. Wright, P.E.
Associate Principal Engineer
_________________________
Kyle R. Campbell, P.E.
Senior Principal Engineer
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL DEVELOPMENT
TALBOT ROAD PROPERTY
2103 TALBOT ROAD SOUTH
RENTON, WASHINGTON
ES-9099
Earth Solutions NW, LLC
15365 Northeast 90th Street, Suite 100
Redmond, Washington 98052
Phone: 425-449-4704 | Fax: 425-449-4711
www.earthsolutionsnw.com
07/18/2023
07/18/2023
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
July 18, 2023
ES-9099
Seattle LLL, LLC
325 – 118th Avenue Southeast, Suite 100
Bellevue, Washington 98005
Attention: Lili Lu
Dear Lili:
Earth Solutions NW, LLC (ESNW) is pleased to present this geotechnical report for the proposed
residential development to be constructed along the west side of Talbot Road South, just west of
the intersection with South 21st Street, in Renton, Washington. Based on the results of our
investigation, the proposed residential construction is feasible from a geotechnical standpoint.
Geologic stratigraphy observed at the subsurface exploration locations generally consisted of
about 8 to 30 feet of native glacial till deposits atop competent Renton Formation sandstone and
siltstone bedrock, which extended to the maximum exploration depth of about 80 feet below
existing grades and to the termination depth of all exploratory borings.
The subject site falls entirely within an area identified as a moderate/medium coal mine hazard
area per City of Renton GIS mapping. However, based on the results of our investigation, the
site can be classified as a low coal mine hazard area. In our opinion, the risk of surface
subsidence due to collapsing coal mine workings may be considered very low to negligible based
on the competent underlying geology and lack of coal mine related void space encountered at
the exploration locations. In our opinion, coal mine hazard area regulations and specialized
design considerations regarding potential surface subsidence are not necessary for this project.
As such, the typical residential structure proposed to be constructed on this site can be supported
on conventional spread and continuous foundations bearing on undisturbed competent native
soil, recompacted native soil, or new structural fill placed directly on a competent subgrade.
Competent native soil suitable for foundation support is expected to be encountered beginning
at depths of about two to three feet below existing grades across the site.
The native glacial till and underlying bedrock deposits exhibit very poor infiltration characteristics,
including high relative density, high fines content, and weak cementation. In our opinion, full
infiltration should be considered infeasible from a geotechnical standpoint.
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
Seattle LLL, LLC ES-9099
July 18, 2023 Executive Summary – Page 2
Earth Solutions NW, LLC
This report provides geotechnical analyses and recommendations for the proposed residential
development. The opportunity to be of service to you is appreciated. If you have any questions
regarding the content of this geotechnical engineering study, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
Brian C. Snow, L.G.
Senior Staff Geologist
Earth Solutions NW, LLC
Table of Contents
ES-9099
PAGE
INTRODUCTION ................................................................................. 1
General .................................................................................... 1
Project Description ................................................................. 2
SITE CONDITIONS ............................................................................. 3
Surface ..................................................................................... 3
Subsurface .............................................................................. 3
Topsoil and Fill ............................................................. 4
Native Soil ..................................................................... 4
Bedrock ......................................................................... 4
Geologic Setting ........................................................... 5
Groundwater ................................................................. 6
Geologic Critical Areas Review ............................................. 6
Coal Mine Hazard ......................................................... 7
Landslide Hazard.......................................................... 9
DISCUSSION AND RECOMMENDATIONS ....................................... 9
General .................................................................................... 9
Site Preparation and Earthwork ............................................. 10
Temporary Erosion Control ......................................... 10
Excavations and Slopes .............................................. 10
Structural Fill ................................................................ 11
In-situ and Imported Soil ............................................. 12
Wet Season Grading .................................................... 12
Subgrade Preparation .................................................. 13
Void Space Restoration ............................................... 13
Grading and Excavations in Bedrock ......................... 13
Foundations ............................................................................ 13
Retaining Walls ....................................................................... 14
Seismic Design ....................................................................... 15
Slab-on-Grade Floors ............................................................. 16
Utility Support and Trench Backfill ....................................... 16
Preliminary Pavement Sections ............................................. 17
Drainage................................................................................... 17
Infiltration Feasibility ................................................... 18
Preliminary Stormwater Vault Design ........................ 18
LIMITATIONS ...................................................................................... 20
Additional Services ................................................................. 20
Earth Solutions NW, LLC
Table of Contents
Cont’d
ES-9099
GRAPHICS
Plate 1 Vicinity Map
Plate 2 Boring Location Plan
Plate 3 Geologic Map
Plate 4 Historical Coal Mine Map K32 A
Plate 5 LiDAR-Based Shaded Relief Map
Plate 6 Retaining Wall Drainage Detail
Plate 7 Footing Drain Detail
APPENDICES
Appendix A Subsurface Exploration Logs
Appendix B Laboratory Test Results
Earth Solutions NW, LLC
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL DEVELOPMENT
TALBOT ROAD PROPERTY
2103 TALBOT ROAD SOUTH
RENTON, WASHINGTON
ES-9099
INTRODUCTION
General
This geotechnical engineering study was prepared for the proposed residential development to
be constructed on the west side of Talbot Road South, just west of the intersection with South
21st Street, in Renton, Washington. The purpose of this study was to provide geotechnical
recommendations to support the current development plans, as understood at the time of this
study. To fulfill our scope of services, the following tasks were completed:
Subsurface exploration to characterize the soil and groundwater conditions and to assess
potential coal mine hazards on site.
Laboratory testing of representative soil samples collected at the exploration locations.
Infiltration feasibility evaluation based primarily on our field observations and laboratory
analyses.
Engineering analyses and recommendations for the proposed residential development.
Literature review of historical coal mine maps and related documentation.
Preparation of this report.
The following documents and resources were reviewed as part of our report preparation:
Pre-Application Submittal, prepared by D.R. Strong Consulting Engineers, dated October
13, 2022.
Feasibility Layout, prepared by D.R. Strong Consulting Engineers, Project No. 22058,
dated July 28, 2022.
Geologic Map of the Renton Quadrangle, King County, Washington, by Mullineaux, D.R.,
dated 1965.
Web Soil Survey (WSS), online resource maintained by the Natural Resources
Conservation Service (NRCS) under the United States Department of Agriculture (USDA).
Seattle LLL, LLC ES-9099
July 18, 2023 Page 2
Earth Solutions NW, LLC
Soil Survey of King County Area, Washington, by Snyder, D.E., Gale, P.S., and Pringle,
R.F., USDA Soil Conservation Service, issued November 1973.
Geology of the Renton, Auburn, and Black Diamond Quadrangles, King County,
Washington: A Study of Cenozoic Bedrock and Surficial Deposits in the Southeastern Part
of the Puget Sound Lowland, Geological Survey Professional Paper 672, by Mullineaux,
D.R., United States Geological Survey, dated 1970.
Chapter 4 (Soil and Rock Classification and Logging) of the WSDOT Geotechnical Design
Manual, M 46-03.16, dated February 2022.
Geologic Information Portal, online resource maintained by the Washington State
Department of Natural Resources (DNR).
Faults and Earthquakes in Washington State, by Czajkowski and Bowman, endorsed by
the Washington State Department of Natural Resources, dated 2014.
King County Landslide Hazard Areas, Map 12-1, prepared by Tetra Tech, Inc. and
endorsed by the King County Flood Control District, dated May 2010.
King County Liquefaction Susceptibility, Map 11-5, prepared by Tetra Tech, Inc. and
endorsed by the King County Flood Control District, dated May 2010.
Renton Municipal Code (RMC) Title IV, Chapter 3, Section 4-3-050.
Project Description
The subject site consists of a single tax parcel (King County Parcel No. 722200-0175) located on
the west side of Talbot Road South, just west of the intersection with South 21st Street, in Renton,
Washington. Site-specific development plans were not available for review. However, per the
referenced feasibility layout, we understand the site is proposed to be developed with six
residential lots, an access road, a stormwater facility, and other associated improvements.
At the time of report submission, specific building load values were not available for review;
however, we anticipate that typical two- to three-story residential structures will be constructed,
consisting of relatively lightly loaded wood framing supported on conventional foundations.
Based on our experience with similar developments, we estimate wall loads of about 2 to 3 kips
per linear foot and slab-on-grade and column loading of 150 pounds per square foot (psf) will be
incorporated into the final design.
If the above design assumptions either change or are incorrect, ESNW should be contacted to
review the recommendations provided in this report. ESNW should review final designs to verify
the geotechnical recommendations provided in this report have been incorporated into the plans.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 3
Earth Solutions NW, LLC
SITE CONDITIONS
Surface
The subject site is located on the west side of Talbot Road South, just west of the intersection
with South 21st Street, in Renton, Washington. The site is comprised of a single tax parcel (King
County Parcel No. 722200-0175) and totals roughly 1.39 acres in area. The approximate site
location is depicted on Plate 1 (Vicinity Map).
Based on the Public Land Survey System (PLSS), the site is located in the southeast quarter of
the southeast quarter of section 19, township 23 north, range 5 east (SE 1/4 SE 1/4 S19, T23N,
R5E). Approximated site locations shown on Plates 3 through 5 (introduced in later sections of
this report) are based on measurements from PLSS section lines, which are illustrated on the
attached graphics. Please note that the map on Plate 4 delineates each quarter of sections 19
(SE 1/4), 20 (SW 1/4), 29 (NW 1/4), and 30 (NE 1/4) within T23N, R5E. Plates 3 and 5 do not
illustrate section quarters, but instead only depict section boundaries with respect to the PLSS.
The site is currently developed with a single-family residence, outbuildings, and associated
improvements. Undeveloped portions of the site are primarily surfaced with grasses and
landscaping areas. Surface topography descends from east to west at gentle gradients, with an
estimated 30 to 35 feet of total vertical relief across the site. The site is bordered to the north and
south by existing residential development, to the east by Talbot Road South, and to the west by
Shattuck Avenue South.
Subsurface
An ESNW representative observed, logged, and sampled five borings between May 15 and May
17, advanced at accessible locations within the property boundaries using a track-mounted mud-
rotary drill rig and operators retained by ESNW.
The subsurface exploration locations were selected to avoid existing improvements and utility
lines and based on historical coal mine mapping (described later in this report) in areas most
probable to encounter historical mine workings. The purpose of the subsurface exploration was
to assess and classify the site soils, to characterize the groundwater conditions within areas
proposed for new development, and to evaluate the risk of surface subsidence (and other
hazards) due to suspected historical coal mine workings near the subject site. The soil borings
were advanced to a maximum depth of about 80 feet bgs, and all explorations were terminated
within undisturbed, competent Renton Formation bedrock.
The approximate locations of the borings are depicted on Plate 2 (Boring Location Plan). Please
refer to the exploration logs provided in Appendix A for a more detailed description of subsurface
conditions. Representative soil samples collected at our exploration sites were analyzed in
general accordance with Unified Soil Classification System (USCS) and USDA methods and
procedures.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 4
Earth Solutions NW, LLC
Topsoil and Fill
Topsoil thickness was not directly observed during the subsurface exploration. Sampling
methods employed during mud-rotary drilling typically bypass surficial topsoil layers, and the
shallowest samples were collected at five feet bgs across the site during the exploration.
In any case, based on our experience in the project vicinity, typical topsoil sections range in
thickness from about 6 inches up to about 18 inches. It is possible that deeper or shallower
pockets of topsoil are present in localized areas across the site. Thickness of the topsoil layer is
heavily influenced historical site activities such as previous development, site grading, or
agricultural practices. Topsoil can commonly be characterized by its dark brown color, the
presence of fine organic material, and small root intrusions.
Fill was not encountered at the exploration locations. Fill may be present in isolated areas of the
site, such as the “dirt mounds” indicated on the referenced feasibility layout in the western site
portion, or in areas surrounding existing site improvements and utilities. However, deep (i.e.,
greater than five feet thick), widespread fills were not observed during the subsurface exploration
and are not expected to be present at the subject site.
Native Soil
In general, geologic stratigraphy can be characterized as glacial till deposits atop Renton
Formation siltstone and sandstone bedrock. Thickness of the glacial till deposit varied from about
8 feet in the western portion of the site near Shattuck Avenue South, up to about 30 feet in the
eastern portion near Talbot Road South.
Visual and laboratory classifications of the samples collected from the glacial till deposits
characterized the soils primarily as silty sand (USCS: SM) with minor amounts of scattered gravel.
The native soils frequently exhibited zones of light iron oxide staining and weak cementation,
which are typical of glacial till deposits. Blow counts recorded during the exploratory drilling
indicate the glacial till is chiefly in a very dense condition (i.e., N>50), with isolated areas of
medium dense to dense near surface deposits (i.e., at B-3, B-4, and B-5, within five feet of the
existing ground surface).
Based on the laboratory analyses, the silty sands contain considerable fines between about 42
and 49 percent. At boring B-2, the surficial soils were classified as a sandy silt, with fines contents
of up to about 58 percent. Soil moisture was characterized as moist to wet, and moisture content
typically ranged between about 10 and 20 percent.
Bedrock
Renton Formation bedrock was encountered at all five boring locations, and all borings were
terminated within very dense, undisturbed bedrock deposits. As noted above, depth to bedrock
varied from about 8 feet in the western portion of the site near Shattuck Avenue South, up to
about 30 feet in the eastern portion near Talbot Road South. The observed bedrock was visually
classified to include both sandstone and siltstone members of the Renton Formation. Trace to
minor amounts of coal, present in millimeter-scale laminations or as sand-sized clasts, was
observed throughout the explored bedrock strata and at variable depths.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 5
Earth Solutions NW, LLC
Relevant geotechnical descriptors were taken from the referenced WSDOT Geotechnical Design
Manual and incorporated into the characterization of bedrock encountered during the
investigation. As such, the sandstone member was primarily characterized as light gray (N7),
medium to coarse grained, fresh (Grade I), very weak to moderately weak rock (R1 to R2), with
isolated areas in the upper part of the formation characterized as moderate yellowish brown
(10YR 6/6) and slightly weathered (Grade II). Similarly, the deeper siltstone member was
characterized primarily as very dense, moist, light gray (N7), fine grained, fresh (Grade I),
extremely to very weak rock (R0 to R1). N-values recorded throughout the bedrock profile
observed during the exploration correlate to very dense deposits (i.e., N>50).
At all boring locations, sandstone was the first rock type encountered beneath the glacial till cap.
The sandstone member extended to the termination depth of borings B-3 and B-5. Underlying
the sandstone and extending to the termination depth of borings B-1, B-2, and B-4, siltstone was
encountered at depths of roughly 58 feet, 25 feet, and 40 feet, respectively.
The sandstone member was encountered in a relatively weathered condition at borings B-1 and
B-2, becoming unweathered and gray at depths between roughly 25 and 30 feet. At borings B-3
through B-5, unweathered sandstone was encountered at the upper bedrock surface and
extended to the termination depth or the contact with the underlying siltstone. In general, the
upper sandstone member was easily friable within the sample spoons, lacking strong
cementation and a fine-grained cohesive matrix. Siltstones encountered across the site were in
a relatively unweathered condition throughout the observed geologic profiles.
In general, drilling through the sedimentary rocks was relatively slow, and the drill rig exhibited
consistent drilling behavior indicating relatively uniform conditions and a lack of void spaces (such
as an abandoned coal mine tunnel). We utilized two different drilling bits within the bedrock units:
a tricone bit (standard bit for mud-rotary in the Puget Sound) was utilized to penetrate the upper
glacial till and sandstone bedrock strata where the probability of encountering gravel clasts was
higher (tricones are more durable through gravels). Once the boreholes were advanced through
the till and upper sandstone members, the drill rig was retooled with a drag bit, providing
increased drilling efficiency through the relatively dense and fine-grained lower sandstone and
siltstone members.
Evidence of both primary and secondary bedrock structures were observed within the collected
samples. Bedding was evidenced in both silt- and sandstone members by the presence of
millimeter-scale laminations, although some sections of bedrock were “massively” bedded (i.e.,
no bedding). Direct measurements of structural attitude and bedding orientation were not
possible; however, it should be noted that the observed laminations described above were in a
near-vertical orientation relative to the sampling spoon, indicating that sedimentary bedding
within the Renton Formation beneath the subject site dips at high angles relative to horizontal.
Geologic Setting
Geologic mapping of the area indicates the site is underlain primarily by Vashon-age ground
moraine (Qgt) deposits. Along the western property line and parallel with Shattuck Avenue South,
Renton Formation bedrock (Tr) is identified and extends west to the Green River valley floor. The
geologic map also depicts the presence of the Talbot Syncline just north of the subject site. A
portion of the referenced geologic map is included on Plate 3 of this report.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 6
Earth Solutions NW, LLC
Ground moraine deposits are synonymous with glacial till deposits and are locally divided into
“lodgment till” and “ablation till.” Lodgment till generally consists of a compact and unsorted
mixture of gravel, sand, silt, and clay that is commonly referred to as “hardpan.” Ablation till is
similar but is typically much less compact and coherent. Renton Formation bedrock is
characterized as arkosic sandstone, mudstone, and shale containing coal beds mostly near the
base or middle of the formation. Renton Formation bedrock is also characterized by its numerous
faults of small displacement and wavy bedding.
A syncline is a fold or “trough” in which initially horizontal and planar geologic strata are deformed
into concave upward geometry by compressional tectonic stresses. The fold axis, or the
centerline of the fold, crosscuts immediately north of the subject property in an east-southeast,
west-northwest orientation. A detailed characterization of regional geology is available in the
referenced Geological Survey professional paper.
The online WSS resource identifies Beausite gravelly sandy loam on 6 to 15 percent slopes (Map
Unit Symbol: BeC) as the primary soil unit underlying the site. Beausite soils formed in glacial
deposits underlain by sandstone at depth, and support vegetation including alder, fir, cedar, and
associated brush and shrubs. Per the referenced USDA soil survey, the native soils are
characterized with medium surface water runoff and moderate hazard of water erosion.
In our opinion, the site geology and soil conditions are consistent with the published resources
outlined in this section.
Groundwater
Groundwater was not observed at the boring locations primarily due to the pressurized injection
of drilling fluids utilized in mud-rotary drilling techniques, which inherently obscures the
observation of natural groundwater. However, based on the conditions encountered, in our
opinion, significant quantities of groundwater are unlikely to be present at the subject site. If
encountered, groundwater flow rates would be expected to be relatively light.
It should be noted that zones of perched groundwater seepage are common within glacial
deposits, particularly along sections of sloping topography, and groundwater seeps should be
expected within site excavations at depth. Groundwater seepage 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.
Geologic Critical Areas Review
ESNW reviewed Title IV, Chapter 3, Section 4-3-050 – Critical Areas Regulations – of the Renton
Municipal Code (RMC) to assess the presence of geologic critical areas at the subject site.
ESNW also reviewed the City of Renton’s online GIS “COR” mapping resource, which depicts
suspected critical areas throughout the jurisdiction. Regulated geologic critical areas within the
City of Renton (City) include steep slopes, landslide hazards, erosion hazards, seismic hazards,
and coal mine hazards.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 7
Earth Solutions NW, LLC
Based on our review, the critical areas mapping indicates a moderate coal mine hazard area is
present at the subject site. High and moderate landslide hazard areas are also indicated just off
the northwest property corner, and isolated areas of “regulated slopes” are mapped around the
site perimeters, most notably along the eastern property line. However, slope heights within
areas identified as regulated slopes are limited to about five feet maximum per the COR map
resource, and slope gradients are below the threshold to be classified as either “sensitive” or
“protected” slopes.
Coal Mine Hazard
The subject site falls entirely within an area identified as a moderate/medium coal mine hazard
area per City of Renton GIS mapping. Moderate/medium coal mine hazards are defined in the
RMC as: areas where mine workings are deeper than two hundred feet (200’) for steeply dipping
seams, or deeper than fifteen (15) times the thickness of the seam or workings for gently dipping
seams. These areas may be affected by subsidence.
Historical mine mapping available through Washington State DNR’s online Geologic Information
Portal indicates the subject site is bordered on both north and south sides by abandoned
underground coal mines, including the Old Patton and Sunbeam mines. We selected one map
(Coal Mine Map K32 A) from the DNR catalogue to include on Plate 4 of this report. In our
opinion, Map K32 A effectively and representatively illustrates the approximate site location and
surrounding historical coal mining activity.
Based on the historical mapping reviewed, it appears that mine entrances for the Sunbeam Mine
(south of the subject site) were opened along the lower portion of the eastern Green River valley
wall at elevations between roughly 50 and 65 feet. Records of the Old Patton Mine (north of the
subject site) are significantly less detailed than those of the Sunbeam mine; however, it is
presumed that mine entrances for the Old Patton Mine were opened in a similar fashion along
the eastern Green River valley wall.
Notably, the fold axis of the Talbot Syncline (also named the Patton Syncline), which crosscuts
the region in an east-southeast, west-northwest orientation, separates the Sunbeam and Old
Patton mines. Assuming the Talbot Syncline has relatively symmetrical fold geometry (and the
axial plane is relatively vertical), historical mine workings for the Old Patton mine are likely at
comparable elevations to those for the Sunbeam mine, as both mines are roughly equidistant
from the fold axis.
Based on topographic information available through the COR mapping resource, surface
elevations at the subject site range from roughly 166 feet in the northwest site corner to about
198 feet along the eastern property line. As depicted on the historical DNR coal mine maps,
mined-out areas within the Sunbeam Mine were surveyed at roughly elevation 69 feet. As such,
we would expect that historical coal mine workings would be at least 97 to 129 feet bgs assuming
horizontal geologic stratigraphy. However, per the geologic map, the Renton Formation
stratigraphy underlying the subject site and surrounding area are deformed into concave upward
geometry (a syncline). Based on our subsurface observations and structural measurements on
the geologic map, strata within the Renton Formation beneath the subject site dip at steep angles
towards the north. Per the historical coal mine mapping, dip angles within the mining zone of the
Sunbeam Mine are documented between 55 and 65 degrees to the north.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 8
Earth Solutions NW, LLC
As such, given the synclinal fold geometry and the relative location of the subject site roughly 200
to 500 feet north (down dip) of mapped, known mine workings, the coal seam targeted by the
nearby mining operations is expected to be deepest along the fold axis. Therefore, we would
expect that if mining operations had progressed directly beneath the subject site, the abandoned
workings would be deeper than the estimated elevations of coal mine workings assuming
horizontal stratigraphy above (i.e., 97 to 129 feet bgs), as the mining operation would have been
advanced down dip and at progressively lower elevations approaching the fold axis.
Readily available LiDAR mapping of the subject site reveals potential mining related disturbances
west of the site – apparent fill deposits and roadcuts are present on the eastern Green River
valley wall near the Sunbeam Mine entrance, and consistent with the depiction of historical mine
workings shown on the historical coal mine maps. However, mining related disturbances and
evidence of surface subsidence are not visible within the site boundaries on the LiDAR mapping.
A LiDAR-based shaded relief map of the subject site is included on Plate 5.
Geologic stratigraphy observed at the boring locations was generally characterized as about 8 to
30 feet of glacial till deposits atop competent Renton Formation sandstone and siltstone
bedrock. Undisturbed Renton Formation bedrock extended to the termination depth of all five
borings advanced across the property, and no evidence of open voids, loose or collapsed coal
mine workings, or thick coal seams was observed within any of the boreholes.
Historical mine maps do not illustrate mined-out areas directly beneath the subject site. However,
based on the COR mapping of moderate/medium coal mine hazard areas encompassing the
subject site, undocumented mining may have occurred. The subsurface explorations were
advanced to a maximum depth of about 80 feet bgs, and as such, we are unable to conclusively
rule out the presence of abandoned mine workings within the upper 200 feet of existing grades.
In consideration of the evidence and reasoning outlined above, however, it is our opinion that the
site can be classified as a low coal mine hazard. Low coal mine hazards are defined in the RMC
as: areas with no known mine workings and no predicted subsidence. While no mines are known
in these areas, undocumented mining is known to have occurred.
In our opinion, the risk of surface subsidence due to collapsing coal mine workings may be
considered very low to negligible based on the competent underlying geology and lack of coal
mine related void space encountered at the exploration locations. In our opinion, coal mine
hazard area regulations and specialized design considerations regarding potential surface
subsidence are not necessary for this project.
Per the RMC, any hazards found during development activities shall be immediately reported to
both ESNW and the Development Services Division. Any coal mine hazards shall be mitigated
prior to re-commencing construction based on supplemental recommendations or reports
prepared by the geotechnical professional.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 9
Earth Solutions NW, LLC
Landslide Hazard
High and moderate landslide hazard areas are indicated on the COR map resource just off the
northwest property corner. However, the referenced landslide hazard area map does not depict
the same hazard area. In our opinion, based on our observations of very dense glacial till and
competent Renton Formation bedrock underlying the subject site and topographic data depicted
on the COR map, the mapped landslide hazard area is in error. Slope gradients surrounding the
site generally fall below the 15 percent threshold to be classified as high or medium landslide
hazards. Low landslide hazard areas include any areas with slopes less than 15 percent.
Therefore, the site and immediately surrounding area can be classified as a low landslide hazard
area.
In our opinion, the risk of landsliding as a result of existing and/or proposed site development
activities should be considered very low to negligible on account of the very dense and competent
underlying geology.
DISCUSSION AND RECOMMENDATIONS
General
Based on the results of our investigation, the proposed residential construction is feasible from a
geotechnical standpoint. The primary geotechnical considerations associated with the proposed
project include earthwork, temporary excavations, structural fill requirements, subgrade
preparation, retaining wall foundation support, slab-on-grade support, utility support and trench
backfill, drainage, and stormwater management.
Geologic stratigraphy observed at the subsurface exploration locations generally consisted of
about 8 to 30 feet of native glacial till deposits atop competent Renton Formation sandstone and
siltstone bedrock, which extended to the maximum exploration depth of about 80 feet below
existing grades and to the termination depth of all exploratory borings.
The subject site falls entirely within an area identified as a moderate/medium coal mine hazard
area per City of Renton GIS mapping. However, based on the results of our investigation, the
site can be classified as a low coal mine hazard area. In our opinion, the risk of surface
subsidence due to collapsing coal mine workings may be considered very low to negligible based
on the competent underlying geology and lack of coal mine related void space encountered at
the exploration locations. In our opinion, coal mine hazard area regulations and specialized
design considerations regarding potential surface subsidence are not necessary for this project.
As such, the typical residential structure proposed to be constructed on this site can be supported
on conventional spread and continuous foundations bearing on undisturbed competent native
soil, recompacted native soil, or new structural fill placed directly on a competent subgrade.
Competent native soil suitable for foundation support is expected to be encountered beginning
at depths of about two to three feet below existing grades across the site.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 10
Earth Solutions NW, LLC
The native glacial till and underlying bedrock deposits exhibit very poor infiltration characteristics,
including high relative density, high fines content, and weak cementation. In our opinion, full
infiltration should be considered infeasible from a geotechnical standpoint.
This study has been prepared for the exclusive use of Seattle LLL, LLC, and its representatives.
A warranty is neither expressed nor implied. 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 and
performing site stripping within the designated clearing limits. Subsequent earthwork activities
may involve additional grading and utility installations.
Temporary Erosion Control
The following temporary erosion and sediment control (TESC) Best Management Practices
(BMPs) should be considered:
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.
When not in use, soil stockpiles should be covered or otherwise protected to reduce the
potential for soil erosion, especially during periods of wet weather.
Temporary measures for controlling surface water runoff, such as interceptor trenches,
sumps, or interceptor swales, should be installed prior to beginning earthwork activities.
Dry soils disturbed during construction should be wetted to minimize dust and airborne soil
erosion.
Additional TESC BMPs, as specified by the project civil engineer and indicated on the plans,
should be incorporated into construction activities. TESC BMPs may be modified during
construction as site conditions require and as approved by the site erosion control lead.
Excavations and Slopes
Based on the soil conditions observed at the exploration locations, excavation activities are likely
to expose medium dense to dense native soils within the upper five feet of existing grades,
transitioning to very dense, cemented, and competent glacial till or native Renton Formation
bedrock at depth. The presence of shallow perched groundwater seepage should be anticipated
within site excavations.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 11
Earth Solutions NW, LLC
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)
Loose soil and fill 1.5H:1V (Type C)
Medium dense to dense soil 1H:1V (Type B)
Dense to very dense native soil or bedrock 0.75H:1V (Type A)
Groundwater seepage should be anticipated during excavation activities, particularly if
excavations take place during the wet season. An ESNW representative should observe
temporary excavations to evaluate the presence of groundwater seepage. If seepage is not
observed, steeper temporary slope inclinations may be feasible, particularly where the native,
unweathered, and cemented “hardpan” glacial till deposits are exposed within relatively large,
open excavations.
As previously noted, coal mine related hazards found during development activities shall be
immediately reported to both ESNW and the Development Services Division for remediation.
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. Permanent slopes
should be planted with vegetation to both enhance stability and minimize erosion and should
maintain a gradient of 2H:1V or flatter.
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
The in-situ mineral soils may not be suitable for use as structural fill unless the soil is at (or slightly
above) the optimum moisture content at the time of placement and compaction. Soil shall not be
placed dry of the optimum moisture content and should be evaluated by ESNW during
construction.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 12
Earth Solutions NW, LLC
If native soil is placed below the optimum moisture content, settlement will likely occur during
periods of wet weather. As such, structural fill soils should be properly moisture conditioned, as
necessary, to ensure acceptability of the soil moisture content at the time of placement and
compaction. Native soil will be difficult or impossible to use as structural fill during extended wet
weather conditions. In this respect, moisture conditioning or treatment of the soils may be
necessary at some locations prior to use as structural fill.
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.
In-situ and Imported Soil
The in-situ soils encountered at the subject site have a high sensitivity to moisture and were
generally in a moist to wet condition at the time of exploration. Soils anticipated to be exposed
on site will degrade rapidly if exposed to wet weather and construction traffic. Compaction of the
soil to the levels necessary for use as structural fill may be difficult or impossible during wet
weather conditions, and are likely to be over the optimum moisture content immediately after
excavation.
Soils encountered during site excavations that are excessively over the optimum moisture content
will likely require aeration or treatment prior to placement and compaction. Conversely, soils that
are substantially below the optimum moisture content will require moisture conditioning through
the addition of water prior to use as structural fill. An ESNW representative should be contacted
to evaluate the suitability of the in-situ soil for use as structural fill at the time of construction.
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).
Wet Season Grading
Earthwork activities that occur during the wet season may require additional measures to protect
both structural subgrades and soil intended for use as structural fill. Site-specific
recommendations can be provided at the time of construction and may include leaving cut areas
several inches above design subgrade elevations, covering working surfaces with crushed rock,
protecting structural fill soil from adverse moisture conditions, and additional TESC
recommendations. ESNW can assist in obtaining a wet season grading permit if required by the
governing jurisdiction.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 13
Earth Solutions NW, LLC
Subgrade Preparation
Following site stripping, ESNW should be contacted to observe the subgrade to confirm soil
conditions are as anticipated and to provide supplementary recommendations for subgrade
preparation, as necessary. Such supplementary recommendations for subgrade improvement
may be provided at the time of construction and would likely include further mechanical
compaction 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 the subgrade where existing structures have been removed
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 throughout areas
of future subgrade. 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 re-compaction
and/or overexcavation and replacement, during site preparation activities. ESNW should
also evaluate the overall suitability of prepared subgrade areas following site preparation
activities.
Grading and Excavations in Bedrock
Site grading and excavations may extend into the underlying and relatively competent sandstone
bedrock. The upper surface of Renton Formation bedrock will likely be rippable with conventional
equipment. However, areas of increased difficulty should be anticipated. In our opinion, the
contractor should be prepared with tiger-teeth-fitted excavator buckets for excavations that
extend into the sandstone bedrock, particularly in the western portion of the site where bedrock
was encountered within about eight feet of the existing ground surface. ESNW would be available
during initial mass grading activities to further evaluate rippability of the native bedrock with the
grading contractor, if requested.
Foundations
Typical two- to three-story residential structures constructed on this site can be supported on
conventional spread and continuous footings bearing on competent (undisturbed) native soil,
recompacted native soil, or new structural fill placed directly on a competent subgrade. Provided
site earthwork activities are completed in accordance with our recommendations, suitable soil
conditions should be exposed beginning at depths of about two to three feet bgs.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 14
Earth Solutions NW, LLC
An ESNW representative should be requested to confirm the suitability of foundation subgrades
at the time of construction. If deemed necessary, the undisturbed native soils may be compacted
in situ provided the soil is at or slightly above the optimum moisture content.
Due to the high moisture sensitivity of the site soils, foundation subgrade areas should be
protected from wet weather or areas of remediation should be anticipated; a layer of crushed rock
can be considered to protect foundation subgrade areas. If structural building pads are disturbed
during wet weather, remediation measures such as overexcavation and replacement with rock
may be necessary in some areas.
Provided the structure(s) 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. Most of the
anticipated 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.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 15
Earth Solutions NW, LLC
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 6.
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 and bedrock conditions
encountered at the exploration locations, the parameters and values provided below are
recommended for seismic design per the 2018 IBC.
Parameter Value
Site Class C*
Mapped short period spectral response acceleration, SS (g) 1.427
Mapped 1-second period spectral response acceleration, S1 (g) 0.486
Short period site coefficient, Fa 1.200
Long period site coefficient, Fv 1.500
Adjusted short period spectral response acceleration, SMS (g) 1.712
Adjusted 1-second period spectral response acceleration, SM1 (g) 0.728
Design short period spectral response acceleration, SDS (g) 1.142
Design 1-second period spectral response acceleration, SD1 (g) 0.486
* Assumes very dense native soil and bedrock conditions, encountered to a maximum depth of 80 feet bgs during
the May 2023 field exploration, remain very dense to at least 100 feet bgs.
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.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 16
Earth Solutions NW, LLC
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.
In our opinion, and consistent with the depiction on the referenced liquefaction susceptibility map,
site susceptibility to liquefaction may be considered very low to negligible. The absence of a
shallow groundwater table and the relatively dense and cemented characteristics of the native
soil and bedrock were the primary bases for this opinion.
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.
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-
quarter-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.
Utility Support and Trench Backfill
The native soils observed at the subsurface exploration locations are generally suitable for
support of utilities. Utility trench excavations may encounter bedrock; see above for a discussion
regarding excavations into bedrock.
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. Native soil
will be difficult or impossible to use as utility trench backfill during extended wet weather
conditions. In this respect, moisture conditioning or treatment of the soils may be necessary at
some locations prior to use as structural fill. 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.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 17
Earth Solutions NW, LLC
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.
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).
A minimum of two inches of HMA placed over three inches of asphalt-treated base (ATB).
An ESNW representative 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.
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.
If on-site roads are constructed with an inverted crown, additional drainage measures may be
recommended to assist in maintaining road subgrade and pavement stability.
Drainage
Groundwater seepage will likely be encountered within site excavations depending on the time
of year grading operations take place. Temporary measures to control surface water runoff and
groundwater during construction would likely involve passive elements such as interceptor
trenches, interceptor swales, and sumps. ESNW should be consulted during preliminary grading
to identify areas of seepage and provide recommendations to reduce the potential for seepage-
related instability. The contractor should be prepared to manage areas of groundwater seepage
in excavations.
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. In our opinion, a foundation
drain should be installed along building perimeter footings. A typical foundation drain detail is
provided on Plate 7.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 18
Earth Solutions NW, LLC
Infiltration Feasibility
Based on conditions encountered during the fieldwork, in our opinion, full infiltration should be
considered infeasible from a geotechnical standpoint. Near surface soils consisted of very dense,
weakly cemented glacial till deposits with fines contents between about 42 and 58 percent. The
high relative density, high fines content, and weak cementation of native glacial till soils will
severely limit in-situ hydraulic conductivity. In our opinion, the native glacial till soils and
underlying bedrock should be considered impermeable for design purposes.
If necessary to satisfy project objectives, limited infiltration applications may be feasible within
the upper weathered soil horizon. However, depending on the extent of proposed grade
modifications (i.e., grade cuts and fills), the upper weathered soils are unlikely to remain in an
undisturbed condition, precluding the design and implementation of shallow LID elements.
ESNW would be pleased to further investigate the feasibility of shallow LID elements, upon
request.
Preliminary Stormwater Vault Design
Based on the presence of impermeable glacial till and bedrock deposits, we anticipate a
stormwater detention vault will likely be utilized for stormwater management in the western
portion of the site.
Vault foundations should be supported on very dense, undisturbed native soil, bedrock, or
crushed rock placed on a competent subgrade surface. Based on observations made at boring
location B-1 (within Tract A), vault excavations would be expected to expose dense glacial till
deposits from the surface extending to roughly eight feet bgs. Deeper than eight feet, vault
excavations will likely expose slightly weathered, competent Renton Formation sandstone
bedrock. Minor perched groundwater seepage may be exposed depending on the time of year
excavations occur.
Storm vault designs must incorporate adequate buffer space from property boundaries such that
temporary excavations to construct the vault structure can be successfully completed. Perimeter
drains should be installed around the vault and conveyed to an approved discharge point. The
presence of perched groundwater seepage should be anticipated during excavation activities for
the vault; however, buoyancy is not expected to influence the vault design.
In general, and in anticipation for groundwater seepage to be present within the vault excavation,
Type A and C soils (as described in the Excavations and Slopes section of this report) should be
expected.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 19
Earth Solutions NW, LLC
The following parameters can be used for stormwater vault design:
Allowable soil bearing capacity 5,000 psf
(very dense glacial till or competent
Renton Formation Bedrock)
Active earth pressure (unrestrained) 35 pcf
Active earth pressure (unrestrained, hydrostatic) 80 pcf
At-rest earth pressure (restrained) 55 pcf
At-rest earth pressure (restrained, hydrostatic) 100 pcf
Coefficient of friction 0.40
Passive earth pressure 350 pcf
Seismic surcharge 8H psf*
* Where H equals the retained height.
The passive earth pressure and coefficient of friction values include a safety factor of 1.5. The
vault walls should be backfilled with free-draining material or suitable common earth if a sheet
drain material is used. The upper one foot of the wall backfill can consist of a less permeable
soil, if desired. A perforated drainpipe should be placed along the base of the wall and connected
to an approved discharge location. If the elevation of the vault bottom is such that gravity flow to
an outlet is not possible, the portion of the vault below the drain should be designed to include
hydrostatic pressure. Design values accounting for hydrostatic pressure are included above.
ESNW should observe grading operations for the vault and the subgrade conditions prior to
concrete forming and pouring to confirm conditions are as anticipated, and to provide
supplemental recommendations as necessary. Additionally, ESNW should be contacted to
review final vault designs to confirm that appropriate geotechnical parameters have been
incorporated into the design.
We anticipate native soil will be used as vault backfill. Detention vault backfill should conform to
the specifications of structural fill previously detailed in this report. The native soil is moisture
sensitive and will settle once impacted by wet weather if placed below the optimum moisture
content. ESNW recommends placing the native soil at or slightly above the optimum moisture
content. Native soil placed substantially above the optimum moisture content will require
additional time or remediation prior to supporting a structure.
Seattle LLL, LLC ES-9099
July 18, 2023 Page 20
Earth Solutions NW, LLC
LIMITATIONS
This study has been prepared for the exclusive use of Seattle LLL, 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 neither expressed nor
implied. Variations in the soil and groundwater conditions observed at the exploration 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 BCS Date June 2023
Date 06/07/2023 Proj.No.9099
Plate 1
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
Vicinity Map
Talbot Road Property
Renton,Washington
Reference:
King 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.
SITE
Renton
Plate
Proj.No.
Date
Checked
DrawnEarthSolutionsNWLLC GeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCBoringLocationPlanTalbotRoadPropertyRenton,WashingtonNORTHLEGEND
Approximate Location of
ESNW Boring,Proj.No.
ES-9099,May 2023
Subject Site
Existing Building
Proposed Lot Number
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.
0 2 5 5 0 1 0 0
Sc ale in Feet1"=5 0 '
MRS
BCS
06/15/2023
9099
2
B-1
1
B-2
B-3
B-4
B-5
B-1
TALBOT ROAD S.TALBOT ROAD S.1 2 3
4
5
6
Tract A
170
180 190170
180
190SHATTUCK AVENUE S.
Plate
Proj.No.
Date
Checked
DrawnEarthSolutionsNWLLC GeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCCAM
BCS
06/15/2023
9099
3
Reference:
Geologic Map of The Renton Quadrangle,
King County,Washington
By D.R.Mullineaux
1965
GeologicMapTalbotRoadPropertyRenton,WashingtonNORTH
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.
Approximate
Site Location
Plate
Proj.No.
Date
Checked
DrawnEarthSolutionsNWLLC GeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCCAM
BCS
06/15/2023
9099
4
Reference:
Geologic Structure Map of Renton Coal Mine,
Renton Coal Company,Renton,Washington.
Washington Department of Natural Resources,
Historical Coal Mine Map K32 A
HistoricalCoalMineMapK32ATalbotRoadPropertyRenton,WashingtonNORTH
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.
Approximate
Site Location
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drawn CAM
Checked BCS Date June 2023
Date 06/15/2023 Proj.No.9099
Plate 5
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
Approximate
Site LocationPotentialMining
Related Disturbances
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.
NORTH
LiDAR-Based Shaded Relief Map
Talbot Road Property
Renton,Washington
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drawn MRS
Checked BCS Date June 2023
Date 06/15/2023 Proj.No.9099
Plate 6
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
Talbot Road Property
Renton,Washington
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drawn MRS
Checked BCS Date June 2023
Date 06/15/2023 Proj.No.9099
Plate 7
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
Talbot Road Property
Renton,Washington
Earth Solutions NW, LLC
Appendix A
Subsurface Exploration Logs
ES-9099
Subsurface conditions on site were explored between May 15 and May 17, 2023, by advancing
five borings using a track-mounted mud-rotary drill rig and operators retained by ESNW. The
approximate locations of the exploration sites are illustrated on Plate 2 of this study. The
exploration logs are provided in this Appendix. The borings were advanced to a maximum depth
of about 80 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)
165.0
SS
SS
100
100
15-22-26
(48)
11-20-24
(44)
MC = 13.4
Fines = 49.2
MC = 20.0
SM
Bedrock
Gray silty SAND, dense, moist
[USDA Classification: slightly gravelly LOAM]
-light iron oxide staining
-minor scattered fine gravel
-machine chatter
SANDSTONE (Renton Formation Bedrock), moderate yellowish brown
(10YR 6/6), medium to coarse grained, slightly weathered (Grade II), very
weak to moderately weak rock (R1 to R2)
-heavily oxidized to about 30'
-mm scale laminations
-poorly graded medium to coarse sand grains with silty matrix
8.0DEPTH(ft)0.0
2.5
5.0
7.5
10.0
12.5
15.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/15/23 COMPLETED 5/15/23
GROUND WATER LEVEL:
GROUND ELEVATION 173 ft
LATITUDE 47.46082 LONGITUDE -122.21248
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 1 OF 6
BORING NUMBER B-1
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
143.0
SS
SS
SS
100
100
100
17-50/5"
22-22-32
(54)
50/6"
MC = 16.6
MC = 19.5
MC = 19.5
Bedrock
SANDSTONE (Renton Formation Bedrock), moderate yellowish brown
(10YR 6/6), medium to coarse grained, slightly weathered (Grade II), very
weak to moderately weak rock (R1 to R2) (continued)
-smooth, consistent rig behavior to BOH
-becomes moderate yellowish brown (10YR 6/6) and light gray (N7)
-trace coal present in mm scale laminations and sand-sized clasts
-trace coal present in mm scale laminations
30.0DEPTH(ft)15.0
17.5
20.0
22.5
25.0
27.5
30.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/15/23 COMPLETED 5/15/23
GROUND WATER LEVEL:
GROUND ELEVATION 173 ft
LATITUDE 47.46082 LONGITUDE -122.21248
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 2 OF 6
BORING NUMBER B-1
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
90
100
91
42-50/4"
24-50/6"
40-50/5"
MC = 17.3
MC = 16.2
MC = 18.0
Bedrock
SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to
coarse grained, fresh (Grade I), very weak to moderately weak rock (R1
to R2)
-sample is easily friable
-trace coal in sand-sized clasts
-easily friableDEPTH(ft)30.0
32.5
35.0
37.5
40.0
42.5
45.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/15/23 COMPLETED 5/15/23
GROUND WATER LEVEL:
GROUND ELEVATION 173 ft
LATITUDE 47.46082 LONGITUDE -122.21248
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 3 OF 6
BORING NUMBER B-1
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
118.0
115.0
SS
SS
SS
100
0
67
25-30-
50/6"
50/6"
12-12-15
(27)
MC = 16.4
MC = 27.8
Bedrock
ML
Bedrock
SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to
coarse grained, fresh (Grade I), very weak to moderately weak rock (R1
to R2) (continued)
-minor scattered coal fragments
-inch scale dark brown organic beds
-consistent drilling behavior
-no recovery
Gray SILT, medium dense, wet
SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained,
fresh (Grade I), extremely to very weak rock (R1 to R2)
55.0
58.0DEPTH(ft)45.0
47.5
50.0
52.5
55.0
57.5
60.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/15/23 COMPLETED 5/15/23
GROUND WATER LEVEL:
GROUND ELEVATION 173 ft
LATITUDE 47.46082 LONGITUDE -122.21248
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 4 OF 6
BORING NUMBER B-1
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
100
100
100
50/3"
32-50/4"
50/3"
MC = 12.4
MC = 15.5
MC = 13.4
Bedrock
SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained,
fresh (Grade I), extremely to very weak rock (R1 to R2) (continued)
-trace fine sand
-very slow, consistent drilling to BOH
-weak to moderately lithified
-retool rig with "drag bit", slightly increased drilling efficiencyDEPTH(ft)60.0
62.5
65.0
67.5
70.0
72.5
75.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/15/23 COMPLETED 5/15/23
GROUND WATER LEVEL:
GROUND ELEVATION 173 ft
LATITUDE 47.46082 LONGITUDE -122.21248
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 5 OF 6
BORING NUMBER B-1
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
92.5
SS
SS
100
100
50/2"
50/1"
MC = 11.2
MC = 22.1
Bedrock
SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained,
fresh (Grade I), extremely to very weak rock (R1 to R2) (continued)
Boring terminated at 80.5 feet below existing grade. No groundwater
encountered during drilling. Boring backfilled with grout.
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.
80.5DEPTH(ft)75.0
77.5
80.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/15/23 COMPLETED 5/15/23
GROUND WATER LEVEL:
GROUND ELEVATION 173 ft
LATITUDE 47.46082 LONGITUDE -122.21248
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 6 OF 6
BORING NUMBER B-1
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
160.0
SS
SS
100
100
21-31-45
(76)
50/4"
MC = 6.0
Fines = 57.8
MC = 13.2
ML
Gray sandy SILT, medium dense, moist
-rig chatter, becomes very dense
[USDA Classification: slightly gravelly LOAM]
-light iron oxide staining
-minor scattered fine gravel
-significant machine chatter
15.0DEPTH(ft)0.0
2.5
5.0
7.5
10.0
12.5
15.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/16/23 COMPLETED 5/16/23
GROUND WATER LEVEL:
GROUND ELEVATION 175 ft
LATITUDE 47.46107 LONGITUDE -122.21214
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 1 OF 3
BORING NUMBER B-2
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
150.0
SS
SS
SS
89
100
100
18-32-46
(78)
50/6"
50/2"
MC = 17.8
MC = 17.3
MC = 10.4
Bedrock
Bedrock
SANDSTONE (Renton Formation Bedrock), moderate yellowish brown
(10YR 6/6) and light gray (N7), medium to coarse grained, slightly
weathered (Grade II), very weak to moderately weak rock (R1 to R2)
-relatively friable rock
-slow drilling
SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained,
fresh (Grade I), extremely to very weak rock (R0 to R1)
-moderately to strongly lithified
-very slow, consistent drilling to BOH
25.0DEPTH(ft)15.0
17.5
20.0
22.5
25.0
27.5
30.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/16/23 COMPLETED 5/16/23
GROUND WATER LEVEL:
GROUND ELEVATION 175 ft
LATITUDE 47.46107 LONGITUDE -122.21214
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 2 OF 3
BORING NUMBER B-2
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
134.5
SS
SS
SS
100
100
100
50/5"
50/3"
50/3"
MC = 13.7
MC = 11.4
MC = 14.9
Bedrock
SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained,
fresh (Grade I), extremely to very weak rock (R0 to R1) (continued)
-moderately abundant coal (approximately 20 to 40 percent of sample)
present in mm scale laminations
-laminations are near vertical in orientation
-minor coal (approximately 10 o 15 percent of sample) present in mm
scale laminations
-laminations are near vertical in orientation
Boring terminated at 40.5 feet below existing grade. No groundwater
encountered during drilling. Boring backfilled with grout.
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.
40.5DEPTH(ft)30.0
32.5
35.0
37.5
40.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/16/23 COMPLETED 5/16/23
GROUND WATER LEVEL:
GROUND ELEVATION 175 ft
LATITUDE 47.46107 LONGITUDE -122.21214
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 3 OF 3
BORING NUMBER B-2
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
172.0
SS
SS
100
100
4-6-10
(16)
27-50/3"
MC = 18.9
Fines = 42.3
MC = 12.7
SM
Bedrock
Gray silty SAND, medium dense, moist
[USDA Classification: slightly gravelly fine sandy LOAM]
-minor scattered fine gravel
-light iron oxide staining
SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to
coarse grained, fresh (Grade I), very weak to moderately weak rock (R1
to R2)
-smooth consistent rig behavior to BOH
10.0DEPTH(ft)0.0
2.5
5.0
7.5
10.0
12.5
15.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/16/23 COMPLETED 5/16/23
GROUND WATER LEVEL:
GROUND ELEVATION 182 ft
LATITUDE 47.46083 LONGITUDE -122.21201
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 1 OF 4
BORING NUMBER B-3
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
92
100
67
20-50/6"
50/5"
17-18-23
(41)
MC = 14.3
MC = 17.9
MC = 17.7
Bedrock
SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to
coarse grained, fresh (Grade I), very weak to moderately weak rock (R1
to R2) (continued)
-near vertical, mm scale coal laminations 0-15% coal
-slow drilling, retool rig from tricone bit to drag bit
-easily friable
-near vertical / steeply diping mm scale coal laminations 0-15% coalDEPTH(ft)15.0
17.5
20.0
22.5
25.0
27.5
30.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/16/23 COMPLETED 5/16/23
GROUND WATER LEVEL:
GROUND ELEVATION 182 ft
LATITUDE 47.46083 LONGITUDE -122.21201
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 2 OF 4
BORING NUMBER B-3
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
100
100
100
50/3"
50/5"
50/5"
MC = 18.2
MC = 16.5
MC = 18.2
Bedrock
SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to
coarse grained, fresh (Grade I), very weak to moderately weak rock (R1
to R2) (continued)
-trace coal present in mm scale, near vertical laminationsDEPTH(ft)30.0
32.5
35.0
37.5
40.0
42.5
45.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/16/23 COMPLETED 5/16/23
GROUND WATER LEVEL:
GROUND ELEVATION 182 ft
LATITUDE 47.46083 LONGITUDE -122.21201
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 3 OF 4
BORING NUMBER B-3
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
136.5
SS 100 50/3"MC = 15.3 Bedrock
Boring terminated at 45.5 feet below existing grade. No groundwater
encountered during drilling. Boring backfilled with grout.
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.
45.5DEPTH(ft)45.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/16/23 COMPLETED 5/16/23
GROUND WATER LEVEL:
GROUND ELEVATION 182 ft
LATITUDE 47.46083 LONGITUDE -122.21201
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 4 OF 4
BORING NUMBER B-3
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
171.0
SS
SS
67
100
14-14-19
(33)
25-41-
50/5"
MC = 17.4
Fines = 48.4
MC = 12.7
SM
Brown silty SAND, dense, moist
[USDA Classification: slightly gravelly LOAM]
-light iron oxide staining
-trace scattered fine gravel
-becomes gray, very dense
-reduced oxide staining, weakly cemented
-significant drilling resistance
-rig chatter
15.0DEPTH(ft)0.0
2.5
5.0
7.5
10.0
12.5
15.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/17/23 COMPLETED 5/17/23
GROUND WATER LEVEL:
GROUND ELEVATION 186 ft
LATITUDE 47.46091 LONGITUDE -122.21164
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 1 OF 4
BORING NUMBER B-4
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
161.0
SS
SS
SS
100
100
100
36-45-
50/5"
29-35-47
(82)
50/5"
MC = 16.6
Fines = 47.7
MC = 13.4
MC = 14.9
SM
Bedrock
Brown silty SAND, very dense, moist
[USDA Classification: slightly gravelly LOAM]
-scattered fine to medium gravel in cemented, silty sand matrix
-scattered fine gravel
-weakly cemented
SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to
coarse grained, fresh (Grade I), very weak to moderate weak rock (R1 to
R2)
-friable rock
25.0DEPTH(ft)15.0
17.5
20.0
22.5
25.0
27.5
30.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/17/23 COMPLETED 5/17/23
GROUND WATER LEVEL:
GROUND ELEVATION 186 ft
LATITUDE 47.46091 LONGITUDE -122.21164
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 2 OF 4
BORING NUMBER B-4
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
146.0
SS
SS
SS
100
100
100
50/4"
31-50/5"
50/3"
MC = 13.7
MC = 15.7
MC = 13.2
Bedrock
Bedrock
SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to
coarse grained, fresh (Grade I), very weak to moderate weak rock (R1 to
R2) (continued)
-mm scale coal laminations
-bedding plane is near vertical
-decreasing grain size
SILTSTONE (Renton Formation Bedrock), light gray (N7), fine grained,
fresh (Grade I), extremely to very weak rock (R0 to R1)
-trace coal present in mm scale laminations
-laminations are near vertical in orientation
-increasing sand content
40.0DEPTH(ft)30.0
32.5
35.0
37.5
40.0
42.5
45.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/17/23 COMPLETED 5/17/23
GROUND WATER LEVEL:
GROUND ELEVATION 186 ft
LATITUDE 47.46091 LONGITUDE -122.21164
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 3 OF 4
BORING NUMBER B-4
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
140.5
SS 100 50/3"MC = 20.0 Bedrock
Boring terminated at 45.5 feet below existing grade. No groundwater
encountered during drilling. Boring backfilled with grout.
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.
45.5DEPTH(ft)45.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/17/23 COMPLETED 5/17/23
GROUND WATER LEVEL:
GROUND ELEVATION 186 ft
LATITUDE 47.46091 LONGITUDE -122.21164
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 4 OF 4
BORING NUMBER B-4
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
177.0
SS
SS
39
100
7-7-6
(13)
25-50/6"
MC = 19.4
MC = 12.2
Fines = 48.1
SM
Gray silty SAND, medium dense, moist
-minor scattered fine to medium gravel
[USDA Classification: slightly gravelly LOAM]
-becomes very dense, weakly cemented
15.0DEPTH(ft)0.0
2.5
5.0
7.5
10.0
12.5
15.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/17/23 COMPLETED 5/17/23
GROUND WATER LEVEL:
GROUND ELEVATION 192 ft
LATITUDE 47.46099 LONGITUDE -122.21118
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 1 OF 4
BORING NUMBER B-5
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
162.0
SS
SS
SS
100
100
82
50/6"
50/5"
40-50/5"
MC = 11.4
MC = 11.1
MC = 11.1
SM
Gray silty SAND, very dense, moist
-slight rig chatter
-trace sand-sized coal fragments incorporated into glacial till deposit
30.0DEPTH(ft)15.0
17.5
20.0
22.5
25.0
27.5
30.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/17/23 COMPLETED 5/17/23
GROUND WATER LEVEL:
GROUND ELEVATION 192 ft
LATITUDE 47.46099 LONGITUDE -122.21118
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 2 OF 4
BORING NUMBER B-5
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
100
100
100
50/5"
50/4"
50/6"
MC = 12.6
MC = 14.7
MC = 16.5
Bedrock
SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to
coarse grained, fresh (Grade I), very weak to moderate weak rock (R1 to
R2)
-friable rock
-poorly graded medium to coarse sand grains in silty sand matrixDEPTH(ft)30.0
32.5
35.0
37.5
40.0
42.5
45.0
(Continued Next Page)SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/17/23 COMPLETED 5/17/23
GROUND WATER LEVEL:
GROUND ELEVATION 192 ft
LATITUDE 47.46099 LONGITUDE -122.21118
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 3 OF 4
BORING NUMBER B-5
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
141.5
SS
SS
100
100
50/5"
50/4"
MC = 15.9
MC = 16.3
Bedrock
SANDSTONE (Renton Formation Bedrock), light gray (N7), medium to
coarse grained, fresh (Grade I), very weak to moderate weak rock (R1 to
R2) (continued)
-massive (no bedding)
Boring terminated at 50.5 feet below existing grade. No groundwater
encountered during drilling. Boring backfilled with grout.
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.
50.5DEPTH(ft)45.0
47.5
50.0 SAMPLE TYPENUMBERDRILLING CONTRACTOR Holocene Drilling
DATE STARTED 5/17/23 COMPLETED 5/17/23
GROUND WATER LEVEL:
GROUND ELEVATION 192 ft
LATITUDE 47.46099 LONGITUDE -122.21118
LOGGED BY BCS CHECKED BY HTW
NOTES
SURFACE CONDITIONS Field grass
AT TIME OF DRILLINGAT TIME OF DRILLING
AFTER DRILLING
PAGE 4 OF 4
BORING NUMBER B-5
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GENERAL BH / TP / WELL - 9099.GPJ - GINT US.GDT - 7/18/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
Earth Solutions NW, LLC
Appendix B
Laboratory Test Results
ES-9099
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
49.2
57.8
42.3
48.4
47.7
101/2
COBBLES
Specimen Identification
4
coarse
20 401.5 8 14
USDA: Gray Slightly Gravelly Loam. USCS: SM.
USDA: Gray Slightly Gravelly Loam. USCS: Sandy ML.
USDA: Gray Slightly Gravelly Fine Sandy Loam. USCS: SM.
USDA: Brown Slightly Gravelly Loam. USCS: SM.
USDA: Gray Slightly Gravelly Loam. USCS: SM.
6 60
PERCENT FINER BY WEIGHTD10
0.143
0.089
0.17
0.151
0.167
GRAIN SIZE DISTRIBUTION
100
LL
B-01
B-02
B-03
B-04
B-04
3/4
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
GRAVEL SAND
19
19
19
19
19
%Silt
B-01
B-02
B-03
B-04
B-04
2 2003
Cc CuClassification
%Clay
16
PID60 D30
coarse SILT OR CLAYfinemedium
GRAIN SIZE IN MILLIMETERS
3/8 50
5.0ft.
5.0ft.
5.0ft.
5.0ft.
15.0ft.
5.00ft.
5.00ft.
5.00ft.
5.00ft.
15.00ft.
PL
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GRAIN SIZE USDA ES-9099 TALBOT ROAD PROPERTY.GPJ GINT US LAB.GDT 6/2/23Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
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
48.1
101/2
COBBLES
Specimen Identification
4
coarse
20 401.5 8 14
USDA: Gray Slightly Gravelly Loam. USCS: SM.
6 60
PERCENT FINER BY WEIGHTD10
0.158
GRAIN SIZE DISTRIBUTION
100
LL
B-05
3/4
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
GRAVEL SAND
19
%Silt
B-05
2 2003
Cc CuClassification
%Clay
16
PID60 D30
coarse SILT OR CLAYfinemedium
GRAIN SIZE IN MILLIMETERS
3/8 50
10.0ft.
10.00ft.
PL
PROJECT NUMBER ES-9099 PROJECT NAME Talbot Road Property
GRAIN SIZE USDA ES-9099 TALBOT ROAD PROPERTY.GPJ GINT US LAB.GDT 6/2/23Earth 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-9099
Seattle LLL, LLC
Attention: Lili Lu
D.R. Strong Consulting Engineers
Attention: Maher Joudi, P.E.