HomeMy WebLinkAboutExhibit 19 - Geotechnical Report Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL DEVELOPMENT
LINDSAY ANNEXATION
8014, 8118, 8210, AND 8326 — 172ND STREET NORTHEAST
ARLINGTON, WASHINGTON
ES-9786
15365 NE 90t" Street, Suite 100 • Redmond, WA 98052 • (425) 449-4704
3130 Varney Lane, Suite 105 • Pasco, WA 99301 • (509) 905-0275
esnw.com
PREPARED FOR
MJS INVESTORS
June 28, 2024
Adam Z. Shier, L.G.
Project Geologist
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Henry T. Wright, P.E.
Associate Principal Engineer
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL DEVELOPMENT
LINDSAY ANNEXATION
8014, 8118, 8210, AND 8326 — 172ND STREET NORTHEAST
ARLINGTON, WASHINGTON
ES-9786
Earth Solutions NW, LLC
15365 NE 90t" Street, Suite 100 • Redmond, WA 98052 • (425) 449-4704
3130 Varney Lane, Suite 105 • Pasco, WA 99301 • (509) 905-0275
esnw.com
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GeolechnicalmEngineeping
SubWhile . . . following . . . . . _ . .cost overruns, claims, and help.
The Geoprofessional Business Association (GBA) will not likely meet the needs of a civil-works constructor or even a
has prepared this advisory to help you—assumedly different civil engineer.Because each geotechnical-engineering study
a client representative—interpret and apply this is unique,each geotechnical-engineering report is unique,prepared
geotechnical-engineering report as effectively as solely for the client.
possible. In that way, you can benefit from a lowered Likewise,geotechnical-engineering services are performed for a specific
exposure to problems associated with subsurface project and purpose.For example,it is unlikely that a geotechnical-
conditions at project sites and development of engineering study for a refrigerated warehouse will be the same as
them that,for decades, have been a principal cause one prepared for a parking garage;and a few borings drilled during
of construction delays, cost overruns, claims, a preliminary study to evaluate site feasibility will not be adequate to
and disputes. If you have questions or want more develop geotechnical design recommendations for the project.
information about any of the issues discussed herein,
contact your GBA-member geotechnical engineer. Do not rely on this report if your geotechnical engineer prepared it:
Active engagement in GBA exposes geotechnical • for a different client;
engineers to a wide array of risk-confrontation • for a different project or purpose;
techniques that can be of genuine benefit for • for a different site(that may or may not include all or a portion of
everyone involved with a construction project. the original site);or
before important events occurred at the site or adjacent to it;
e.g.,man-made events like construction or environmental
Understand the Geotechnical-Engineering Services remediation,or natural events like floods,droughts,earthquakes,
Provided for this Report or groundwater fluctuations.
Geotechnical-engineering services typically include the planning,
collection,interpretation,and analysis of exploratory data from Note,too,the reliability of a geotechnical-engineering report can
widely spaced borings and/or test pits.Field data are combined be affected by the passage of time,because of factors like changed
with results from laboratory tests of soil and rock samples obtained subsurface conditions;new or modified codes,standards,or
from field exploration(if applicable),observations made during site regulations;or new techniques or tools.If you are the least bit uncertain
reconnaissance,and historical information to form one or more models about the continued reliability of this report,contact your geotechnical
of the expected subsurface conditions beneath the site.Local geology engineer before applying the recommendations in it.A minor amount
and alterations of the site surface and subsurface by previous and of additional testing or analysis after the passage of time-if any is
proposed construction are also important considerations.Geotechnical required at all-could prevent major problems.
engineers apply their engineering training,experience,and judgment
to adapt the requirements of the prospective project to the subsurface Read this Report in Full
model(s). Estimates are made of the subsurface conditions that Costly problems have occurred because those relying on a geotechnical-
will likely be exposed during construction as well as the expected engineering report did not read the report in its entirety.Do not rely on
performance of foundations and other structures being planned and/or an executive summary.Do not read selective elements only.Read and
affected by construction activities. refer to the report in full.
The culmination of these geotechnical-engineering services is typically a You Need to Inform Your Geotechnical Engineer
geotechnical-engineering report providing the data obtained,a discussion About Change
of the subsurface model(s),the engineering and geologic engineering Your geotechnical engineer considered unique,project-specific factors
assessments and analyses made,and the recommendations developed when developing the scope of study behind this report and developing
to satisfy the given requirements of the project.These reports may be the confirmation-dependent recommendations the report conveys.
titled investigations,explorations,studies,assessments,or evaluations. Typical changes that could erode the reliability of this report include
Regardless of the title used,the geotechnical-engineering report is an those that affect:
engineering interpretation of the subsurface conditions within the context - the site's size or shape;
of the project and does not represent a close examination,systematic
inquiry,or thorough investigation of all site and subsurface conditions. the elevation,configuration,location,orientation,
function or weight of the proposed structure and
Geotechnical-Engineering Services are Performed the desired performance criteria;
the composition of the design team;or
for Specific Purposes, Persons, and Projects, . project ownership.
and At Specific Times
Geotechnical engineers structure their services to meet the specific As a general rule,always inform your geotechnical engineer of project
needs,goals,and risk management preferences of their clients.A or site changes-even minor ones-and request an assessment of their
geotechnical-engineering study conducted for a given civil engineer impact.The geotechnical engineer who prepared this report cannot accept
responsibility or liability for problems that arise because the geotechnical conspicuously that you've included the material for information purposes
engineer was not informed about developments the engineer otherwise only.To avoid misunderstanding,you may also want to note that
would have considered. "informational purposes"means constructors have no right to rely on
the interpretations,opinions,conclusions,or recommendations in the
Most of the "Findings" Related in This Report report.Be certain that constructors know they may learn about specific
Are Professional Opinions project requirements,including options selected from the report,only
Before construction begins,geotechnical engineers explore a site's from the design drawings and specifications.Remind constructors
subsurface using various sampling and testing procedures.Geotechnical that they may perform their own studies if they want to,and be sure to
engineers can observe actual subsurface conditions only at those specific allow enough time to permit them to do so.Only then might you be in
locations where sampling and testing is performed.The data derived from a position to give constructors the information available to you,while
that sampling and testing were reviewed by your geotechnical engineer, requiring them to at least share some of the financial responsibilities
who then applied professional judgement to form opinions about stemming from unanticipated conditions.Conducting prebid and
subsurface conditions throughout the site.Actual sitewide-subsurface preconstruction conferences can also be valuable in this respect.
conditions may differ-maybe significantly-from those indicated in
this report.Confront that risk by retaining your geotechnical engineer Read Responsibility Provisions Closely
to serve on the design team through project completion to obtain Some client representatives,design professionals,and constructors do
informed guidance quickly,whenever needed. not realize that geotechnical engineering is far less exact than other
engineering disciplines.This happens in part because soil and rock on
This Report's Recommendations Are project sites are typically heterogeneous and not manufactured materials
Confirmation-Dependent with well-defined engineering properties like steel and concrete.That
The recommendations included in this report-including any options or lack of understanding has nurtured unrealistic expectations that have
alternatives-are confirmation-dependent.In other words,they are not resulted in disappointments,delays,cost overruns,claims,and disputes.
final,because the geotechnical engineer who developed them relied heavily To confront that risk,geotechnical engineers commonly include
on judgement and opinion to do so.Your geotechnical engineer can finalize explanatory provisions in their reports.Sometimes labeled"limitations,'
the recommendations only after observing actual subsurface conditions many of these provisions indicate where geotechnical engineers'
exposed during construction.If through observation your geotechnical responsibilities begin and end,to help others recognize their own
engineer confirms that the conditions assumed to exist actually do exist, responsibilities and risks.Read these provisions closely.Ask questions.
the recommendations can be relied upon,assuming no other changes have Your geotechnical engineer should respond fully and frankly.
occurred.The geotechnical engineer who prepared this report cannot assume
responsibility or liabilityfor confirmation-dependent recommendations fyou Geoenvironmental Concerns Are Not Covered
fail to retain that engineer to perform construction observation. The personnel,equipment,and techniques used to perform an
environmental study-e.g.,a"phase-one"or"phase-two"environmental
This Report Could Be Misinterpreted site assessment-differ significantly from those used to perform a
Other design professionals'misinterpretation of geotechnical- geotechnical-engineering study.For that reason,a geotechnical-engineering
engineering reports has resulted in costly problems.Confront that risk report does not usually provide environmental findings,conclusions,or
by having your geotechnical engineer serve as a continuing member of recommendations;e.g.,about the likelihood of encountering underground
the design team,to: storage tanks or regulated contaminants.Unanticipated subsurface
• confer with other design-team members; environmental problems have led to project failures.If you have not
• help develop specifications; obtained your own environmental information about the project site,
review pertinent elements of other design professionals'plans and ask your geotechnical consultant for a recommendation on how to find
specifications;and environmental risk-management guidance.
• be available whenever geotechnical-engineering guidance is needed.
Obtain Professional Assistance to Deal with
You should also confront the risk of constructors misinterpreting this Moisture Infiltration and Mold
report.Do so by retaining your geotechnical engineer to participate in While your geotechnical engineer may have addressed groundwater,
prebid and preconstruction conferences and to perform construction- water infiltration,or similar issues in this report,the engineer's
phase observations. services were not designed,conducted,or intended to prevent
migration of moisture-including water vapor-from the soil
Give Constructors a Complete Report and Guidance through building slabs and walls and into the building interior,where
Some owners and design professionals mistakenly believe they can shift it can cause mold growth and material-performance deficiencies.
unanticipated-subsurface-conditions liability to constructors by limiting Accordingly,proper implementation of the geotechnical engineer's
the information they provide for bid preparation.To help prevent recommendations will not of itself be sufficient to prevent
the costly,contentious problems this practice has caused,include the moisture infiltration.Confront the risk of moisture infiltration by
complete geotechnical-engineering report,along with any attachments including building-envelope or mold specialists on the design team.
or appendices,with your contract documents,but be certain to note Geotechnical engineers are not building-envelope or mold specialists.
GEOPROFESSIONAL
BUSINESS
SEA ASSOCIATION
Telephone:301/565-2733
e-mail:info@geoprofessional.org www.geoprofessional.org
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 GBAs 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.
v
June 28, 2024 Earth Solutions NW LLC
ES-9786
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
MJS Investors
11201 Southeast 8th Street, Suite 116
Bellevue, Washington 98004
Attention: Rob Risinger
Dear Rob:
Earth Solutions NW, LLC (ESNW) is pleased to present this geotechnical report to support the
proposed residential construction. Based on the results of our investigation, the proposed
construction is feasible from a geotechnical standpoint. Our field observations indicate the site is
underlain primarily by dense to very dense glacial till deposits.
The proposed residential structures may be supported on conventional continuous and spread
footing foundations bearing on competent native soil, compacted native soil, or new structural fill
placed directly on a competent subgrade. In general, we expect competent native soil suitable
for support of foundations will likely be encountered about two to four feet bgs. Where loose or
unsuitable soil conditions are exposed at foundation subgrade elevations, compaction of the soil
to the specifications of structural fill, or overexcavation and replacement with suitable structural
fill will likely be necessary.
The existing fill is generally underlain by topsoil and is not suitable for structural support as is and
should be removed and replaced with suitable structural backfill. Where encountered, fill intended
for reuse as structural fill must be primarily free of organic and deleterious material and should
be evaluated by ESNW at the time of construction.
Based on our review of the referenced topographic data, a portion of the site meets or exceeds
15 percent gradient, with isolated areas in the southern portion of the site meeting or exceeding
33 percent. As such, City of Arlington regulations regarding disturbance area will likely apply. The
development will likely need to be designed to accommodate the existing topography.
The native glacial till 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 NE 901h Street,Suite 100 • Redmond,WA 98052 • (425)449-4704
3130 Varney Lane,Suite 105 Pasco,WA 99301 • (509)905-0275
esnw.com
MJS Investors ES-9786
June 28, 2024 Executive Summary — Page 2
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
Adam Z. Shier, L.G.
Project Geologist
Earth Solutions NW, LLC
Table of Contents
ES-9786
PAGE
INTRODUCTION ................................................................................. 1
General .................................................................................... 1
Project Description ................................................................. 1
SITE CONDITIONS ............................................................................. 2
Surface..................................................................................... 2
Subsurface .............................................................................. 2
Topsoil and Fill............................................................. 2
NativeSoil..................................................................... 3
Geologic Setting........................................................... 3
Groundwater................................................................. 3
Geologic Hazard Areas Assessment..................................... 4
Landslide Hazard Areas............................................... 4
Slopes ........................................................................... 4
Discussion .................................................................... 5
DISCUSSION AND RECOMMENDATIONS ....................................... 5
General .................................................................................... 5
Site Preparation and Earthwork............................................. 6
Temporary Erosion Control......................................... 6
Excavations and Slopes .............................................. 7
StructuralFill ................................................................ 7
In-situ and Imported Soil ............................................. 8
Wet-Season Grading.................................................... 8
Existing Fill Removal and Replacement..................... 9
Foundations ............................................................................ 9
RetainingWalls ....................................................................... 10
SeismicDesign ....................................................................... 11
Liquefaction.................................................................. 11
Slab-on-Grade Floors ............................................................. 12
Utility Support and Trench Backfill ....................................... 12
Preliminary Pavement Sections............................................. 12
Drainage................................................................................... 13
Infiltration Feasibility ................................................... 14
Detention Pond Recommendations............................ 14
LIMITATIONS...................................................................................... 14
Additional Services................................................................. 14
REFERENCES .................................................................................... 15
Earth Solutions NW, LLC
Table of Contents
Cont'd
ES-9786
GRAPHICS
Plate 1 Vicinity Map
Plate 2 Test Pit Location Plan
Plate 3 Retaining Wall Drainage Detail
Plate 4 Footing Drain Detail
APPENDICES
Appendix A Subsurface Exploration Logs
Appendix B Laboratory Test Results
Earth Solutions NW, LLC
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RESIDENTIAL DEVELOPMENT
LINDSAY ANNEXATION
8014, 8118, 8210, AND 8326 — 172ND STREET NORTHEAST
ARLINGTON, WASHINGTON
ES-9786
INTRODUCTION
General
This geotechnical engineering study (study) was prepared for the proposed residential
construction to be located on the south side of 172nd Street Northeast at 8014, 8118, 8210, &
8326 — 172nd Street Northeast in Arlington, Washington. To fulfill our scope of services, the
following were completed:
• Subsurface exploration to characterize the soil and groundwater conditions.
• Laboratory testing of representative soil samples collected on site.
• Infiltration feasibility evaluation based on field observations and laboratory analyses.
• Engineering analyses and recommendations for the proposed residential construction.
• Preparation of this report.
Project Description
Based on review of the referenced feasibility exhibit, the site will be redeveloped with a series of
new residential lots, access roads, stormwater management facilities, and associated
improvements. At the time of report submission, specific grading and building plans were not
available for review. We anticipate grading for the project will include cuts and fills on the order
of 10 to 15 feet or less to achieve design subgrade and finish grade elevations for the access
drives and building areas. Based on our experience with similar projects, the proposed residential
structures will likely be two to three stories in height and constructed using relatively lightly loaded
wood framing. We anticipate perimeter footing loads will likely be 1 to 2 kips per linear foot,
isolated footing loads will be less than 20 kips, and slab-on-grade loading of 150 pounds per
square foot (psf).
If the above design assumptions either change or are incorrect, ESNW should be contacted to
review the recommendations provided in this report. ESNW should be contacted to review the
final design to confirm that our geotechnical recommendations have been incorporated into the
final plans.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 2
SITE CONDITIONS
Surface
The subject site is located on the south side of 17211 Street Northeast at 8014, 8118, 8210, &
8326 — 172nd Street Northeast in Arlington, Washington, as illustrated on the Vicinity Map (Plate
1). The site consists of five tax parcels (Snohomish County parcel nos. 310525-002-006-00,
310526-100-100, 31052600-100-200, 31052600-102-200, and 31052600-102-300) totaling
32.28 acres. The property is currently developed with a series of single-family residences,
outbuildings, and associated improvements. Undeveloped portions of the property are primarily
surfaced with lawn grass, landscaping areas, access driveways, and forested conditions.
In general, terrain across the subject site descends to the west with approximately 80 feet of
elevation change. Per the PDS Map Portal, an area containing a steep slope (i.e., greater than
33 percent gradient) is present in the western portion of the site. The site is bordered to the north
by 172nd Street Northeast, to the east and south by undeveloped parcels, and to the west by 79th
Avenue Northeast.
Subsurface
A representative of ESNW observed, logged, and sampled 25 test pits on April 2, 2024, advanced
at accessible locations within the property boundaries, using a mini-trackhoe and operator
retained by our firm. The test pits were completed to assess and classify the site soils, to
characterize the groundwater conditions within areas proposed for new development. The
maximum exploration depth was approximately 11 feet below the existing ground surface (bgs),
and all test pits were terminated in undisturbed native soil deposits.
The approximate locations of the test pits are depicted on Plate 2 (Test Pit Location Plan). Please
refer to the test pit logs provided in Appendix A for a more detailed description of subsurface
conditions. Representative soil samples collected at our exploration sites were analyzed in
general accordance with Unified Soil Classification System (USCS) and United States
Department of Agriculture (USDA) methods and procedures.
Topsoil and Fill
Topsoil was generally observed within the upper 4 to 18 inches of existing grades at the test
locations where historic grade modifications have not been made, characterized by its dark brown
color, the presence of fine organic material, and small root intrusions. Furthermore, an
approximately 24 to 36-inch-thick relic topsoil horizon was encountered at TP-6, TP-7, and TP-9
beginning at depths of about one to two feet bgs underlying reworked native material.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 3
Fills were encountered at seven of the test locations (primarily within Snohomish County parcel
number 31052600-102-200), extending up to three and one-half feet bgs. The fill generally
consisted of silty sand or dark brown topsoil (USCS: SM and TPSL, respectively). Where topsoil
fill was observed, the locations had been stripped of their upper weathered soil horizons during
past grading activities and topsoil fill had been placed atop unweathered glacial till.
Native Soil
Underlying the topsoil and fill, native soil consisting primarily of silty sand with gravel (USCS:SM)
was observed. The native silty sand soil was interpreted to be representative of glacial till
deposits, which were widely encountered across the site. The native glacial till deposits were
generally in a medium dense and weathered condition near surface, becoming very dense,
unweathered, and weakly to moderately cemented beginning at depths between roughly one and
one-half to four feet bgs. Some exploration locations appeared to have been stripped of the upper
weathered soil horizons during past grading activities. Laboratory analyses of representative
glacial till soil samples indicate the till deposits contain roughly 20 to 32 percent fines. All native
soil samples were primarily in a moist to wet condition at the time of exploration.
Geologic Setting
Geologic mapping of the area identifies Vashon till (Qvt) as the primary geologic unit underlying
the site. As reported on the geologic map, glacial till is a non-sorted mixture of silt, sand, and
gravel (diamicton), resembling a low strength concrete mix. The glacial till was deposited directly
beneath the glacier as it advanced over bedrock and older Quaternary deposits.
The referenced Web Soil Survey (WSS) identifies Tokul gravelly medial loam (0 to 8 percent
slopes) as the primary soil unit underlying the subject site. Tokul series soils were formed over
glacial till and volcanic ash. The referenced USDA soil survey characterizes this soil unit with
slow to medium surface water runoff, and slight to moderate hazard of water erosion. In general,
runoff and erosivity increase with slope gradient.
In our opinion, the soils observed during our subsurface exploration are generally consistent with
the geologic and soils mapping resources outlined in this section.
Groundwater
Groundwater seepage was observed at 14 of the test pit locations during the fieldwork (April
2024) at depths of about two to three and one-half feet bgs. Groundwater seepage is common
within glacial deposits, and the elevations and/or flow volumes of seepage can fluctuate
depending on many factors, including precipitation duration and intensity, the time of year, and
soil conditions. In general, groundwater elevations and flow rates are higher during the winter,
spring, and early summer months.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 4
Based on the observed groundwater condition, it is our opinion that the contractor should be
prepared to manage and respond to areas of heavy groundwater seepage. Temporary
dewatering and surface and groundwater controls may be necessary during construction, and in
our opinion, a contingency should be provided in the budget to account for groundwater
management.
Geologically Hazardous Areas Assessment
The presence of geologically hazardous areas at or near the subject site was evaluated by
reviewing Part VI of AMC Chapter 20.93 (Geologically Hazardous Areas) along with the
referenced county-wide hazard mapping resources. Geologically hazardous areas in the City of
Arlington include areas susceptible to erosion, sliding, seismicity, or other geological events.
The following sections provide a summary of on-site landslide hazards and slopes. Specific
regulations regarding development on sites with geologically hazardous areas can be found in
AMC 20.93.630.
Landslide Hazard Areas
Section 20.93.600.b.2 of the AMC provides classification criteria for landslide hazard areas.
Utilizing topographic data available through PDS Map Portal, ESNW determined that criterion
E—any area with a slope of 33 percent or greater and with a vertical relief of 10 or more feet
(except areas composed of consolidated rock)—is met in some sloped areas of the western
portion of the site. In our opinion, all other landslide hazard designation criteria are not applicable
to the site. Unless alteration of the steep slope landslide hazard area is approved, minimum buffer
of 50 feet is required from all edges of a landslide hazard area, per AMC 20.93.630.b.2, and
buildings are required to be set back 15 feet from the nearest buffer edge per AMC 20.93.630.b.3.
It is our opinion that the relatively limited areas that appear to be sloped 33 percent or steeper
can be regraded in an engineered manner to effectively eliminate the potential landslide hazard.
If alteration of these areas is pursued, ESNW should be consulted during the development of
grading plans to provide additional recommendations.
Slopes
Slopes are categorized in AMC section 20.93.600.b.3 into moderate and steep slope categories.
Moderate slopes shall include any slope greater than or equal to 15 percent and less than 33
percent, while steep slopes shall include any slope greater than or equal to 33 percent. This
section of the AMC does not require a minimum height of vertical relief to be classified as a
moderate or steep slope. Based on review of the referenced topographic data, a portion of the
site meets or exceeds 15 percent gradient, with isolated areas in the western portion of the site
meeting or exceeding 33 percent.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 5
AMC section 20.93.630.c provides regulation criteria for development on sites with moderate and
steep slopes. Per table 20.93-2, allowable disturbance area is limited depending on slope
gradient. Table 20.93-2 is provided below for reference.
AMC Table 20.93-2: Slope Disturbance Allowed
Slope Disturbance Allowed
1-14% 100%
15-24% 60%
25-32% 45%
33% or greater 0%
Discussion
Certain exceptions to the regulations described above are permitted in the AMC regarding
development on landslide hazard areas and/or moderate and steep slopes. Several of these
exceptions require geotechnical analysis to demonstrate that the proposed development will not
adversely affect adjacent properties and/or that the proposal is designed to mitigate or essentially
eliminate the risk associated with the geologically hazardous area. ESNW recommends the
project team review the development proposal with respect to the requirements provided in the
AMC. As project plans progress, ESNW can provide additional consulting services pertaining to
geologically hazardous areas.
DISCUSSION AND RECOMMENDATIONS
General
In our opinion, the proposed construction is feasible from a geotechnical standpoint. The primary
geotechnical considerations associated with the proposed project include temporary excavations,
structural fill requirements, subgrade preparation, existing fill removal and replacement, utility
support and trench backfill, drainage, and stormwater management.
The proposed residential structures may be supported on conventional continuous and spread
footing foundations bearing on competent native soil, compacted native soil, or new structural fill
placed directly on a competent subgrade. In general, we expect competent native soil suitable
for support of foundations will likely be encountered about two to four feet bgs. Where loose or
unsuitable soil conditions are exposed at foundation subgrade elevations, compaction of the soil
to the specifications of structural fill, or overexcavation and replacement with suitable structural
fill will likely be necessary.
The existing fill is generally underlain by topsoil and is not suitable for structural support as is and
should be removed and replaced with suitable structural backfill. Where encountered, fill intended
for reuse as structural fill must be primarily free of organic and deleterious material and should
be evaluated by ESNW at the time of construction.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 6
Based on our review of the referenced topographic data, a portion of the site meets or exceeds
15 percent gradient, with isolated areas in the southern portion of the site meeting or exceeding
33 percent. As such, City of Arlington regulations regarding disturbance area will likely apply. The
development will likely need to be designed to accommodate the existing topography.
The native glacial till 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.
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
will likely involve additional mass grading and infrastructure 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 reduce 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.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 7
Excavations and Slopes
Based on the soil conditions observed at the exploration locations, excavation activities are likely
to expose loose to medium dense native soils within the upper two to four feet of existing grades,
becoming dense to very dense at depth. 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:1 V (Type C)
• Loose soil 1.51-1:1 V (Type C)
• Medium dense to dense soil 1 H:1 V (Type B)
• Very dense "hardpan" native soil 0.751-1:1 V (Type A)
Groundwater seepage should be anticipated during excavation activities, especially if
excavations take place during the wet season. An ESNW representative should be requested
observe temporary excavations to evaluate the presence of groundwater seepage. If seepage is
not observed, steeper temporary slope inclinations may be feasible pending evaluation by the
geotechnical engineer.
An ESNW representative should be requested to 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:1 V 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
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 8
The existing soil 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.
With respect to underground utility installations and backfill, local jurisdictions may dictate the soil
type(s) and compaction requirements. Areas of unsuitable material (such as peat, organic-rich
soil, and other debris) should be removed from structural areas and replaced with structural fill.
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
soils to the levels necessary for use as structural fill may be difficult to impossible during wet
weather conditions. 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 requested to determine the suitability of in-situ soils 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
The site soils are highly moisture sensitive; therefore, 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.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 9
Existing Fill Removal and Replacement
At several of the test locations, loose existing fill containing variable amounts of organic debris
was observed. The existing silty sand fill was encountered to depths of up to two feet bgs and
the buried relic organic soils was observed to depths of up to three and one-half feet bgs. The
existing fill is not suitable for structural support as is and should be removed and replaced with
suitable structural backfill. The following is recommended for fill removal and replacement in
structural areas.
• Remove existing fill soil, segregate organic and deleterious material from mineral soil,
stockpile, and protect from moisture; ESNW can evaluate suitability of remaining mineral
soil for reuse as structural fill, if requested.
• If moderate to heavy groundwater seepage is present following removal, place a layer of
quarry spalls on the exposed subgrade and cover with filter fabric to establish a stable
surface.
• Begin mass grading with structural fill, utilizing the stockpiled existing fill if deemed suitable
by ESNW. Aeration or cement treatment of existing fill may be necessary to meet the
specifications for structural fill.
Foundations
The proposed residential structures constructed on this site can be supported on conventional
spread and continuous footings bearing on competent (undisturbed) native soil, compacted native
soil, or new structural fill placed directly on a competent subgrade.
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. An ESNW representative should be requested to confirm
suitability of foundation subgrades at the time of construction. 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
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 10
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.
Retaining walls should be backfilled with free-draining material that extends along the height of
the wall and a distance of at least 18 inches behind the wall. The upper 12 inches of the wall
backfill may consist of a less permeable soil, if desired.
Drainage should be provided behind retaining walls such that hydrostatic pressures do not
develop. If drainage is not provided, hydrostatic pressures should be included in the wall design.
A perforated drainpipe should be placed along the base of the wall and connected to an approved
discharge location. A typical retaining wall drainage detail is provided on Plate 3.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 11
Seismic Design
The 2021 International Building Code (2021 IBC) recognizes ASCE 7-16 (formally known as the
Minimum Design Loads and Associated Criteria for Buildings and Other Structures manual) for
seismic design, specifically with respect to earthquake loads. Based on the soil conditions
encountered at the test pit and boring locations, the parameters and values provided below are
recommended for seismic design per the 2021 IBC.
Parameter Value
Site Class C*
Mapped short period spectral response acceleration, Ss (g) 1.044
Mapped 1-second period spectral response acceleration, Si (g) 0.372
Short period site coefficient, Fa 1.200
Long period site coefficient, F„ 1.500
Adjusted short period spectral response acceleration, SMs (g) 1.253
Adjusted 1-second period spectral response acceleration, SM1 (g) 0.559
Design short period spectral response acceleration, SIDS (g) 0.835
Design 1-second period spectral response acceleration, SD1 (g) 0.372
* Assumes very dense soil conditions, encountered to a maximum depth of 11 feet bgs during the April 2024 field
exploration, remain very dense to at least 100 feet bgs. Based on our experience with the project geologic setting
(glacial till) across the Puget Sound region, soil conditions are likely consistent with this assumption.
Liquefaction
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. Fine sand or silt soil profiles that are loose, cohesionless, and inundated with
groundwater 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,
the native soils are characterized with a very low or negligible susceptibility to liquefaction. The
composition and relatively high density of the native soil were the primary bases for this opinion.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 12
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 soils observed at the subsurface exploration locations are generally suitable for support of
utilities. Use of the native soil as structural backfill in the utility trench excavations will depend on
the in-situ moisture content at the time of placement and compaction. If native soil is placed below
the optimum moisture content, settlement will likely occur once wet weather impacts the trenches.
As such, backfill soils should be properly moisture conditioned, as necessary, to ensure
acceptability of the soil moisture content at the time of placement and compaction. Native soil will
be difficult or impossible to use as utility trench backfill during extended wet weather conditions.
In this respect, aeration or treatment of the soils may be necessary 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.
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 paving.
Where applicable, 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:
• Two inches of hot-mix asphalt (HMA) placed over four inches of crushed rock base (CRIB),
or;
• Two inches of HMA placed over three inches of asphalt-treated base (ATB).
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 13
Heavier traffic areas generally require thicker pavement sections depending on site usage,
pavement life expectancy, and site traffic. For preliminary design purposes, the following
pavement sections for occasional truck traffic and access roadways areas may be considered:
• Three inches of HMA placed over six inches of CRIB, or;
• Three inches of HMA placed over four-and-one-half inches of ATB.
A representative of ESNW should be requested to observe subgrade conditions prior to
placement of CRIB 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, upon request. Road standards utilized by the governing jurisdiction may
supersede the recommendations provided in this report. The HMA, ATB, and CRIB 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
D 1557.
If on-site roads will be constructed with an inverted crown, additional drainage measures must be
included in the road design to assist in maintaining road subgrade and pavement stability. ESNW
can provide further consultation and design considerations regarding roadway drainage if
inverted crowns will be included in the project design, upon request.
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.
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 4.
If buildings will incorporate crawl spaces rather than slab-on-grade, in our opinion, a crawl space
drain system will provide adequate drainage in lieu of perimeter footing drains. The crawl space
drain must provide positive drainage to an appropriate outlet.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 14
Infiltration Feasibility
The City of Arlington adopts the Washington State Department of Ecology Stormwater
Management Manual for Western Washington (2019 SWMMWW)for design and implementation
of new stormwater facilities. Based on our review of the 2019 SWMMWW, limiting factors for on-
site infiltration can be found in Volume V, Chapter 5, Section 5.6 "Site Suitability Criteria" (SSC);
specifically, SSC-1 and SSC-5.
The dense, cemented, and unweathered glacial till soils (hardpan) observed at depths beginning
at about two to four feet bgs generally exhibit very poor soil infiltration characteristics, which is
exhibited by the zones of perched groundwater seepage and iron oxide staining. In our opinion,
the unweathered glacial soils should be considered impermeable for stormwater design
purposes. The use of full infiltration systems for stormwater control is not recommended for this
site.
Detention Pond Recommendations
ESNW understands a detention pond will be constructed near the western property boundary on
parcel no. 31052600-100-200. ESNW should have the opportunity to review the proposed
detention pond plans. Of particular concern is detention pond berm construction and preventing
hydraulic communication with surrounding perched groundwater. Pond berms should include a
keyway and material should be consistent with applicable governing jurisdiction specifications.
Pond berm construction should be observed by ESNW representatives on a nearly full-time basis
to ensure that the material placed is within specifications, geometry is consistent with the plans
and to provide additional recommendations, where applicable.
LIMITATIONS
This study has been prepared for the exclusive use of MJS Investors 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.
Earth Solutions NW, LLC
MJS Investors ES-9786
June 28, 2024 Page 15
REFERENCES
• Feasibly Exhibit, prepared by ESM Consulting Engineers, LLC, dated November 14, 2023
• Geologic Map of the Arlington West 7.5-minute Quadrangle, Snohomish County,
Washington, by James P. Minard, dated 1985
• WSS, maintained by the Natural Resources Conservation Service under the USDA
• Soil Survey of Snohomish County Area, Washington, by Debose and Klungland, United
States Department of Agriculture, Soil Conservation Service, issued July, 1983
• Snohomish County Geologic Hazards Seismic Hazard Areas Map, dated February 1, 2016
• Snohomish County Geologic Hazards Mine Hazard Areas Map, dated February 1, 2016
• Liquefaction Susceptibility Map of Snohomish County, Washington, prepared by Palmer,
S.P. et al., endorsed by the Washington State Department of Natural Resources, dated
September 2004
• AMC
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Lindsay Annexation
Arlington, Washington
NOTE:This plate may contain areas ofcolor.ESNW cannot be Drawn MRS Date 06/13/2024 PrOj. No. 9786
responsible for any subsequent misinterpretation ofthe information
resulting from black&White reproductions ofthis plate. Checked AZS Date June 2024 Plate 1
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purposes or precise scale measurements,but only to illustrate the •
' approximate test locations relative to the approximate locations of
400 existing and/or proposed site features.The information illustrated
TP-S1� ' is largely based on data provided by the client at the time of our
study.ESNWcannotbe responsible forsubsequent des changes
______ '� I `, i or interpretation ofthe data by others.
Drawn
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410
NOTE:This plate may contain areas of color.ESNW cannot be Checked
responsible for any subsequent misinterpretation of the infomration AZS
resulting from black&white reproductions of this plate. Date
06/12/2024
Proj. No.
9786
Plate
2
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NOTES: (Surround in Drain Rock)
• 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 SCHEMATIC ONLY- NOT TO SCALE
of Free-draining Backfill, per ESNW NOT A CONSTRUCTION DRAWING
recommendations.
• Drain Pipe should consist of perforated,
rigid PVC Pipe surrounded with 1-inch
Drain Rock.
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Lindsay Annexation
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Drawn MRS Date 06/13/2024 Proj. No. 9786
Checked AZS Date June 2024 Plate 3
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to Footing Drain.
SCHEMATIC ONLY- NOT TO SCALE
• Surface Seal to consist of NOT A CONSTRUCTION DRAWING
12" of less permeable, suitable
soil. Slope away from building.
LEGEND:
V
Surface Seal: native soil or
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1-inch Drain Rock
Footing Drain Detail
Lindsay Annexation
Arlington, Washington
Drawn MRS Date 06/13/2022 Proj. No. 9786
Checked AZS Date June 2024 Plate 4
Appendix A
Subsurface Exploration Logs
ES-9786
Subsurface conditions on site were explored on April 2, 2024, by advancing 25 test pits using a
machine and an operator retained by ESNW. The approximate locations of the test pits are
illustrated on Plate 2 of this study. The test pit logs are provided in this Appendix. The test pits
were advanced to a maximum depth of about 11 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.
Earth Solutions NW, LLC
I
a) Well-graded gravel with Moisture Content Symbols
��, GW or without sand, little to
o .� O Dry
Absence of moisture,dusty,d to Cement grout
c 4 no fines y dry
U j L 11 the touch ATD=At time surface seal
of drilling
O c 0 Bentonite
0 0 Lo oo° uoan Poorly graded gravel with Damp-Perceptible moisture,likely below chips
Z Static water
�o o v o O GP or without sand, little to optimum MC 1
no fines level(date) Grout
> 0 Moist-Damp but no visible water, likely seal
(D a) U at/near optimum MC - Filter pack with
0o ao o blank casing
Silty gravel with or without section
0 0 a) o o GM Sand Wet-Water visible but not free draining,
N �_ likely above optimum MC Screened casing
or Hydrotip with
U) O � o SaturatedNVater Bearing-Visible free filter pack
- Z
U) > Clayey gravel with or water,typically below groundwater table End cap
O to GC LL ^ without sand
a) a) 0 Terms Describing Relative Density and Consistency
_ c
Coarse-Grained Soils: Test Symbols&Units
Well-graded sand with
o a) $W Or without gravel, little to Density SPT blows/foot Fines=Fines Content
rn o " a) a�°°°°°°°°°°° ( )
0 0 M > c no fines Very Loose <4
UO o Loose 4 to 9 MC=Moisture Content(%)
U (A a:•.::..:•.:.:
M -- "t LO::,•;::::;.•. Poorly graded sand with DD-D Density cf
a) o v :.:::;;.• $p or without gravel, little to
Medium Dense 10 to 29 -Dry y(P )
(3) 0 Z no fines Dense 30 to 49 Str=Shear Strength(tsf)
O a) Very Dense >_50
O Silty sand with or without PID=Photoionization Detector(ppm)
M cn`.,.'
0 ":'`' SM Fine-Grained Soils: OC=Organic Content(%)
c c::: ::•..:. gravel
o Consistency. SPT blows/foot CEC=Cation Exchange Capacity(meq/100 g)
C - NN Very Soft <2
M LL — Clayey sand with or LL=Liquid LimitU) ^ SC without gravel Soft 2 to 3
Medium Stiff 4 to 7 PL=Plastic Limit(%)
o Silt with or without sand Stiff 8 to 14 PI=Plasticity Index(%)
LO Very Stiff 15 to 29
C: ML or gravel; sandy or
U gravelly silt Hard >_30
a�
Clay of low to medium
(3) U u, Component Definitions
a>i � IS CL plasticity; lean clay with
U) N .- or without sand or gravel; Descriptive Term Size Range and Sieve Number
00 E _ _ sandy or gravelly lean clay Boulders Larger than 12"
— J
Cn N U) Cobbles 3"to 12"
�o zo _= GL Organic clay or silt of
low plasticity Gravel 3"to No.4(4.75 mm)
o (n J Coarse Gravel 3"to 3/4"
c U — Fine Gravel 3/4"to No.4(4.75 mm)
O Elastic silt with or without Sand No.4(4.75 mm)to No.200(0.075 mm)
O 0 MH sand or gravel; sandy or Coarse Sand No.4(4.75 mm)to No. 10(2.00 mm)
c O U) g gravelly elastic silt Medium Sand No. 10(2.00 mm)to No.40(0.425 mm)
E 2 N 0 Fine Sand No.40(0.425 mm)to No.200(0.075 mm)
0 U o Clay of high plasticity; Silt and Clay Smaller than No.200(0.075 mm)
CH fat clay with or without
sand or gravel; sandy or Modifier Definitions
U gravelly fat clay
—_ Percentage by
U) Weight(Approx.) Modifier
_� Organic clay or silt of
J OH medium to high plasticity <5 Trace(sand,silt,clay,gravel)
I'llI'll5 to 14 Slightly(sandy,silty,clayey,gravelly)
U
rn C .o PT
Peat, muck, and other 15 to 29 Sandy,silty,clayey,gravelly
2)U) — highly organic soils
Q >_30 Very(sandy,silty,clayey,gravelly)
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
ii FILL Made Ground 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.
Y Earth Solutions NWuc
Geoteehnieat Engineering,Construction EXPLORATION LOG KEY
qWEObservatioa/Testing and Environmental Services
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-1
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 402 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15081 LONGITUDE -122.11826
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
TPSL ..\a 0.6 -roots,probed 9"-12" 401.4
Brown silty SAND with gravel,medium dense, moist to wet
GB MC=39.1 SM
2.0 400.0
Gray silty SAND with gravel, medium dense to dense,moist
2.5
GB MC=16.7 -heavy iron oxide staining,probed 4"
-weakly cemented,becomes dense to very dense
SM -probed 1"-2"
5.0
GB MC=11.9 7.0 395.0
Test pit terminated at 7.0 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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.
a
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-2
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 405 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15008 LONGITUDE -122.11920
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
TPSL Dark brown TOPSOIL
0.5 -roots 404.5
Brown silty SAND with gravel,medium dense, moist
SM
1.5 403.5
Gray silty SAND with gravel,dense to very dense, moist
GB MC=19.5 -light groundwater seepage,probed 0"-1"
2.5
moderately cemented
GB MC=10.3
5.0 SM
7.5
GB MC=11.0 8.0 397.0
Test pit terminated at 8.0 feet below existing grade.Groundwater seepage encountered at
2.0 feet during excavation. No caving observed.
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
N complete understanding of subsurface conditions.
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-3
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 412 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14937 LONGITUDE -122.11820
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
TPSL i o 7 -roots,probed 18" 411.3
Brown silty SAND with gravel,loose to medium dense, moist to wet
GB MC=47.0
SM
2.0 410.0
Gray silty SAND with gravel,dense,moist
2.5 -moderate groundwater seepage
GB MC=17.3 -weakly cemented,light iron oxide staining
probed 6"
SM -probed 0"-1"
5.0
GB MC=11.1 7.0 405.0
Test pit terminated at 7.0 feet below existing grade.Groundwater seepage encountered at
2.0 feet during excavation. No caving observed.
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.
a
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-4
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 206 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15034 LONGITUDE -122.11812
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
-probed 9"-12"
1.0 205.0
Brown silty SAND with gravel,loose to medium dense, moist to wet
GB MC=34.1 [USDA Classification:very gravelly sandy LOAM]
Fines=29.1 SM
2.5
3.0 203.0
Gray silty SAND with gravel,dense,moist to wet
-probed 1"-2"
GB MC=24.2 moderate iron oxide staining
5.0
SM
moderately cemented, becomes very dense
7.5 M1 GB MC=12.2 7.5 198.5
Test pit terminated at 7.5 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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.
a
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-5
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 402 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15099 LONGITUDE -122.11931
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
TPSL:\"r . -probed 12"-16"
-. 1.5 400.5
Brown silty SAND,loose to medium dense,moist
GB MC=13.6
2.5 SM
3.5 398.5
Gray silty SAND with gravel,dense to very dense, moist
-probed 0"
tj GB MC=18.2
-moderately cemented
5.0 SM
C'B MC=13.5 6.5 395.5
Test pit terminated at 6.5 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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.
a
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-6
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 406 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14958 LONGITUDE -122.11970
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Brown silty SAND,loose,moist(Fill)
SM -probed 16"
1.0 405.0
Dark brown TOPSOIL(Fill)
TPSL
12.0 404.0
GB MC=25.0 Gray silty SAND with gravel,dense to very dense, moist to wet
2.5
-probed 0"
-moderate iron oxide staining
SM
5.0
GB MC=10.6 7.0 399.0
Test pit terminated at 7.0 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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.
a
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-7
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 407 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14899 LONGITUDE -122.12014
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Brown silty SAND,loose,moist(Fill)
SM -probed 12"-16"
1.5 405.5
Dark brown TOPSOIL(Fill)
2 5 TPSL
13.0 404.0
Gray silty SAND with gravel,dense to very dense, moist
GB MC=19.3 -light groundwater seepage,probed 0"
-heavy iron oxide staining
5.0 SM
-strongly cemented
GB MC=12.3 7.0 400.0
Test pit terminated at 7.0 feet below existing grade.Groundwater seepage encountered at
3.0 feet during excavation. No caving observed.
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.
a
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-8
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 407 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14831 LONGITUDE -122.12005
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Brown silty SAND,loose,moist
-probed 12"-16"
SM
1.5 405.5
Gray silty SAND with gravel,dense,moist
GB MC=15.5
2.5
-heavy iron oxide staining,weakly cemented
SM
5.0
GB MC=11.0 6.5 400.5
Test pit terminated at 6.5 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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.
a
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-9
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 409 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14870 LONGITUDE -122.11976
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Brown silty SAND,very loose to loose,moist(Fill)
-probed 24"
GB MC=26.0 SM [USDA Classification:gravelly LOAM]
Fines=41.5 -cobbles
2.0 407.0
Dark brown TOPSOIL(Fill)
2.5 TPSL
-roots,probed 12"
3.0 406.0
Gray silty SAND with gravel,dense,moist
-light groundwater seepage
GB MC=19.7 -weakly cemented
-probed 0"
5.0 SM
GB MC=12.2 7.0 402.0
Test pit terminated at 7.0 feet below existing grade.Groundwater seepage encountered at
3.0 feet during excavation. No caving observed.
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.
a
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-10
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 404 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14864 LONGITUDE -122.12066
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
TPSL i -probed 12"
0.7 403.3
Brown silty SAND,loose to medium dense,moist
SM
-light groundwater seepage
2.0 402.0
Gray silty SAND with gravel,dense,moist
2.5 -light groundwater seepage
GB MC= 16.4 -iron oxide staining
SM -moderately cemented, probed 0"
5.0
GB MC=10.4 6.5 397.5
Test pit terminated at 6.5 feet below existing grade.Groundwater seepage encountered at
2.0 feet during excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-11
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 404 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14923 LONGITUDE -122.12054
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL(Fill)
TPSL
light groundwater seepage
1.5 402.5
Gray silty SAND with gravel,dense,moist
GB MC=19.8
2.5
moderate iron oxide staining
SM
5.0
GB MC=9.9 J 1.� 7.0 397.0
Test pit terminated at 7.0 feet below existing grade.Groundwater seepage encountered at
2.0 feet during excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-12
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 407 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14930 LONGITUDE -122.12000
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL(Fill)
-probed 12"
TPSL
12.0 405.0
Gray silty SAND with gravel,dense,moist
2.5
GB MC=41.7 -light groundwater seepage
-moderate iron oxide staining
SM -weakly cemented
5.0
GB
MC=11.7 7.0 400.0
Test pit terminated at 7.0 feet below existing grade.Groundwater seepage encountered at
2.0 feet during excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-13
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 403 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14996 LONGITUDE -122.12029
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Exposed soil AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
TPSL Dark brown TOPSOIL, roots
0.5 -probed 12" 402.5
Brown silty SAND with gravel,loose,wet
GB MC=78.5 SM
2.0 401.0
GB MC=24.0 Gray silty SAND with gravel,dense,moist
2.5
probed 0"
-iron oxide staining
SM
5.0
-becomes very dense,moderately cemented
GB MC=8.5 7.0 396.0
Test pit terminated at 7.0 feet below existing grade.Groundwater seepage encountered at
2.0 feet during excavation.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-14
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 389 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14959 LONGITUDE -122.12214
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
TPSL .
Dark brown TOPSOIL, roots
b 0.6 388.4
Brown silty SAND,medium dense,wet
GB MC=39.6 SM -probed 10"
2.5
3.0 386.0
Gray silty SAND with gravel,very dense,moist
GB MC=12.7
-probed 0"
5.0
SM -strongly cemented
GB MC=7.4 6.5 382.5
Test pit terminated at 6.5 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-15
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 400 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.14963 LONGITUDE -122.12124
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ w~ _
wv J TESTS 0-O MATERIAL DESCRIPTION
❑ �Z o
Q O
U)
0.0
Dark brown TOPSOIL(Fill)
TPSL
1.6 398.4
Gray silty SAND with gravel,dense to very dense, moist
GB MC=17.7
2.5
SM
5.0
GB MC=7.6 6.0 394.0
Test pit terminated at 6.0 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-16
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 400 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15040 LONGITUDE -122.12091
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
TPSL N'.
0.7 399.3
Brown silty SAND with gravel,medium dense,wet
GB MC=53.7 SM -probed 2"
2.5 2.5 397.5
Gray silty SAND with gravel,dense,moist
-heavy groundwater seepage
GB MC=14.0
-probed 0"-1"
SM
5.0
6.5 393.5
Test pit terminated at 6.5 feet below existing grade.Groundwater seepage encountered at
2.5 feet during excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-17
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 403 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15044 LONGITUDE -122.11984
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
TPSL i,.,i i; -probed 8"-10"
0.8 402.2
Brown silty SAND,loose to medium,moist to wet
SM
GB MC=43.7
2.0 401.0
Gray silty SAND with gravel,dense,moist
2.5 -moderate groundwater seepage
-moderate iron oxide staining
GB MC=11.5 [USDA Classification:very gravelly sandy LOAM]
Fines=20.2
-moderately cemented
SM
5.0
GB MC=8.3 7.0 396.0
Test pit terminated at 7.0 feet below existing grade.Groundwater seepage encountered at
2.0 feet during excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-18
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 400 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15102 LONGITUDE -122.11972
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
probed 18"
1.0 399.0
Brown silty SAND with gravel,loose,wet
GB MC=42.7 SM
2.5
3.0 397.0
Gray silty SAND with gravel,dense,moist to wet
GB MC=17.7
-probed 0"
5.0
SM
7.5
IN GB I MC=11.6 8.0 392.0
Test pit terminated at 8.0 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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
N complete understanding of subsurface conditions.
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-19
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 391 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15143 LONGITUDE -122.12137
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
TPSL ..a robed 4"
0.6 p 390.4
Brown silty SAND,loose to medium dense,wet
GB MC=40.8 SM
2.5 2.5 388.5
Gray silty SAND with gravel,dense to very dense, moist
-light groundwater seepage
GB MC=17.4
-probed 0"
5.0
SM -weakly cemented
GB MC=9.0 7.0 384.0
Test pit terminated at 7.0 feet below existing grade.Groundwater encountered at 2.5 feet
during excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-20
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 394 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15067 LONGITUDE -122.12156
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
TPSL i,. a i; -probed 10"
0.8 393.2
Brown silty SAND,medium dense,wet
SM
GB MC=41.8
2.0 392.0
Gray silty SAND with gravel,dense,moist
2.5 -light groundwater seepage
GB MC=16.8 -moderately cemented, probed 0"
iron oxide staining
SM
5.0
GB I MC=8.7 7.0 387.0
Test pit terminated at 7.0 feet below existing grade.Groundwater seepage encountered at
2.0 feet during excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-21
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 384 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15110 LONGITUDE -122.12206
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
probed 12"
1.0 383.0
Brown silty SAND,medium dense,moist to wet
GB MC=39.0 SM
2.0 382.0
Gray silty SAND,dense, moist
2•5 -probed 0"
GB MC=19.5 -moderate iron oxide staining
-weakly cemented
SM
5.0
GB MC=8.7 7.0 377.0
Test pit terminated at 7.0 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-22
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 336 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15084 LONGITUDE -122.12432
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Brown silty SAND,loose,wet(Fill)
SM
-probed 18"
1.5 334.5
Dark brown TOPSOIL(Fill)
2.5 TPSL
13.5 332.5
Gray silty SAND with gravel,dense,moist
-heavy groundwater seepage
GB MC= 18.9 -probed 1"
-light iron oxide staining
5.0
becomes medium dense to dense
GB MC= 13.6
7.5 SM
N 10.0
W
N
H
[USDA Classification:gravelly sandy LOAM]
GB MC=15.5 11.0 325.0
Fines=31.9 Test pit terminated at 11.0 feet below existing grade.Groundwater seepage encountered
at 3.5 feet during excavation. No caving observed.
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.
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-23
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 347 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15152 LONGITUDE -122.12423
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
TPSL ..a robed 10"
0.6 p 346.4
Brown silty SAND,loose to medium dense,moist
GB MC=22.0
SM
2.5
3.0 344.0
Gray silty SAND with gravel,very dense,moist
-light groundwater seepage
GB MC=12.1
5.0 SM
GB MC=19.2 7.0 340.0
Test pit terminated at 7.0 feet below existing grade.Groundwater seepage encountered at
3.0 feet during excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-24
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 368 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15077 LONGITUDE -122.12301
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ ~w _
wv J TESTS Q O MATERIAL DESCRIPTION
❑ a-Z o
Q O
U)
0.0
Dark brown TOPSOIL
probed 10"
1.0 367.0
Brown silty SAND with gravel,loose to medium dense, moist to wet
GB MC=16.4 SM
2.5
-probed 6"
3.5 364.5
Gray silty SAND with gravel,dense,moist
GB MC=15.8 -probed 0"
5.0
-moderately cemented
SM
7.5
GB MC=14.7 8.0 360.0
Test pit terminated at 8.0 feet below existing grade.No groundwater encountered during
excavation. No caving observed.
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
N complete understanding of subsurface conditions.
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
.. 15365 NE 90th Street,Suite 100 TEST PIT NUMBER TP-25
Redmond,WA 98052 PAGE 1 OF 1
Office(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
DATE STARTED 4/2/24 COMPLETED 4/2/24 GROUND ELEVATION 358 ft
EXCAVATION CONTRACTOR NW Excavating LATITUDE 48.15139 LONGITUDE -122.12363
LOGGED BY AZS CHECKED BY RAC GROUND WATER LEVEL:
NOTES SZ AT TIME OF EXCAVATION
SURFACE CONDITIONS Field grass AFTER EXCAVATION
w
_ w~ _
wv J TESTS 0-O MATERIAL DESCRIPTION
❑ �Z o
Q O
U)
0.0
Dark brown TOPSOIL
probed 8"
1.0 357.0
Brown silty SAND with gravel,medium dense, moist
2.5 SM
GB MC= 15.0
4.0 354.0
Gray silty SAND with gravel,dense,moist
5.0 SM
GB MC=11.1 6.0 352.0
Test pit terminated at 6.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
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.
N
W
N
H
N
7
H
Z_
a
c7
r
rn
J
J
W
a
x
m
J
W
Z
W
Appendix B
Laboratory Test Results
ES-9786
Earth Solutions NW, LLC
,. 15365 NE 90th Street,Suite 100 GRAIN SIZE DISTRIBUTION
Redmond,WA 98052
NoOffice(425)449-4704 1 esnw.com
Branch Office:Pasco, WA
PROJECT NUMBER ES-9786 PROJECT NAME Lindsay Annexation
U.S.SIEVE OPENING IN INCHES U.S.SIEVE NUMBERS I HYDROMETER
6 4 3 2 1 1/23/8 3 4 6 810 14 16 20 30 40 50 60 100 140 200
100
95
90
85
80
75
70
65
Lu 6
w 0
� 55
m
w 50
z
LL
H 45
z
w
40
w
a
35
30
25
20
15
10
5-
0-
100 10 1 0.1 0.01 0.001
o GRAIN SIZE IN MILLIMETERS
COBBLES GRAVEL SAND SILT OR CLAY
coarse fine coarse medium fine
z
Specimen Identification Classification Cc CU
a
z • TP-04 1.50ft. USDA: Brown Very Gravelly Sandy Loam. USCS: SM with Gravel.
m TP-09 1.00ft. USDA: Brown Gravelly Loam. USCS: SM with Gravel.
z A TP-17 3.00ft. USDA: Gray Very Gravelly Sandy Loam. USCS: SM with Gravel.
z
a
* TP-22 11.00ft. USDA: Gray Gravelly Sandy Loam. USCS: SM with Gravel.
z
z
Specimen Identification D100 D60 D30 D10 LL PL PI %Silt F %Clay
6 • TP-04 1.5ft. 37.5 1.246 0.081 29.1
w
o m TP-09 1.0ft. 19 0.287 41.4
w A TP-17 3.Oft. 37.5 2.37 0.164 20.2
N
z * TP-22 11.0ft. 19 0.359 31.9
a