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EarthSolutions
NW LLC
Geotechnical Engineering
Construction Observation/Testing
Environmental Services
15365 N.E.90th Street,Suite 100 Redmond,WA 98052
(425)449-4704 Fax (425)449-4711
www.earthsolutionsnw.com
GEOTECHNICAL ENGINEERING STUDY
PROPOSED SHORT PLAT
1400 ABERDEEN AVENUE NORTHEAST
RENTON,WASHINGTON
ES-7334
PREPARED FOR
MAINVUE WA, LLC
March 16, 2021
_________________________
Keven D. Hoffmann, P.E.
Senior Project Manager
_________________________
Kyle R. Campbell, P.E.
Principal Engineer
GEOTECHNICAL ENGINEERING STUDY
PROPOSED SHORT PLAT
1400 ABERDEEN AVENUE NORTHEAST
RENTON, WASHINGTON
ES-7334
Earth Solutions NW, LLC
15365 Northeast 90th Street, Suite 100
Redmond, Washington 98052
Phone: 425-449-4704 | Fax: 425-449-4711
www.earthsolutionsnw.com
03/16/2021
Geotechnical-Engineering Report
Important Information about This
Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.
While you cannot eliminate all such risks, you can manage them. The following information is provided to help.
The Geoprofessional Business Association (GBA)
has prepared this advisory to help you – assumedly
a client representative – interpret and apply this
geotechnical-engineering report as effectively as
possible. In that way, you can benefit from a lowered
exposure to problems associated with subsurface
conditions at project sites and development of
them that, for decades, have been a principal cause
of construction delays, cost overruns, claims,
and disputes. If you have questions or want more
information about any of the issues discussed herein,
contact your GBA-member geotechnical engineer.
Active engagement in GBA exposes geotechnical
engineers to a wide array of risk-confrontation
techniques that can be of genuine benefit for
everyone involved with a construction project.
Understand the Geotechnical-Engineering Services
Provided for this Report
Geotechnical-engineering services typically include the planning,
collection, interpretation, and analysis of exploratory data from
widely spaced borings and/or test pits. Field data are combined
with results from laboratory tests of soil and rock samples obtained
from field exploration (if applicable), observations made during site
reconnaissance, and historical information to form one or more models
of the expected subsurface conditions beneath the site. Local geology
and alterations of the site surface and subsurface by previous and
proposed construction are also important considerations. Geotechnical
engineers apply their engineering training, experience, and judgment
to adapt the requirements of the prospective project to the subsurface
model(s). Estimates are made of the subsurface conditions that
will likely be exposed during construction as well as the expected
performance of foundations and other structures being planned and/or
affected by construction activities.
The culmination of these geotechnical-engineering services is typically a
geotechnical-engineering report providing the data obtained, a discussion
of the subsurface model(s), the engineering and geologic engineering
assessments and analyses made, and the recommendations developed
to satisfy the given requirements of the project. These reports may be
titled investigations, explorations, studies, assessments, or evaluations.
Regardless of the title used, the geotechnical-engineering report is an
engineering interpretation of the subsurface conditions within the context
of the project and does not represent a close examination, systematic
inquiry, or thorough investigation of all site and subsurface conditions.
Geotechnical-Engineering Services are Performed
for Specific Purposes, Persons, and Projects,
and At Specific Times
Geotechnical engineers structure their services to meet the specific
needs, goals, and risk management preferences of their clients. A
geotechnical-engineering study conducted for a given civil engineer
will not likely meet the needs of a civil-works constructor or even a
different civil engineer. Because each geotechnical-engineering study
is unique, each geotechnical-engineering report is unique, prepared
solely for the client.
Likewise, geotechnical-engineering services are performed for a specific
project and purpose. For example, it is unlikely that a geotechnical-
engineering study for a refrigerated warehouse will be the same as
one prepared for a parking garage; and a few borings drilled during
a preliminary study to evaluate site feasibility will not be adequate to
develop geotechnical design recommendations for the project.
Do not rely on this report if your geotechnical engineer prepared it:
• for a different client;
• for a different project or purpose;
• for a different site (that may or may not include all or a portion of
the original site); or
• before important events occurred at the site or adjacent to it;
e.g., man-made events like construction or environmental
remediation, or natural events like floods, droughts, earthquakes,
or groundwater fluctuations.
Note, too, the reliability of a geotechnical-engineering report can
be affected by the passage of time, because of factors like changed
subsurface conditions; new or modified codes, standards, or
regulations; or new techniques or tools. If you are the least bit uncertain
about the continued reliability of this report, contact your geotechnical
engineer before applying the recommendations in it. A minor amount
of additional testing or analysis after the passage of time – if any is
required at all – could prevent major problems.
Read this Report in Full
Costly problems have occurred because those relying on a geotechnical-
engineering report did not read the report in its entirety. Do not rely on
an executive summary. Do not read selective elements only. Read and
refer to the report in full.
You Need to Inform Your Geotechnical Engineer
About Change
Your geotechnical engineer considered unique, project-specific factors
when developing the scope of study behind this report and developing
the confirmation-dependent recommendations the report conveys.
Typical changes that could erode the reliability of this report include
those that affect:
• the site’s size or shape;
• the elevation, configuration, location, orientation,
function or weight of the proposed structure and
the desired performance criteria;
• the composition of the design team; or
• project ownership.
As a general rule, always inform your geotechnical engineer of project
or site changes – even minor ones – and request an assessment of their
impact. The geotechnical engineer who prepared this report cannot accept
responsibility or liability for problems that arise because the geotechnical
engineer was not informed about developments the engineer otherwise
would have considered.
Most of the “Findings” Related in This Report
Are Professional Opinions
Before construction begins, geotechnical engineers explore a site’s
subsurface using various sampling and testing procedures. Geotechnical
engineers can observe actual subsurface conditions only at those specific
locations where sampling and testing is performed. The data derived from
that sampling and testing were reviewed by your geotechnical engineer,
who then applied professional judgement to form opinions about
subsurface conditions throughout the site. Actual sitewide-subsurface
conditions may differ – maybe significantly – from those indicated in
this report. Confront that risk by retaining your geotechnical engineer
to serve on the design team through project completion to obtain
informed guidance quickly, whenever needed.
This Report’s Recommendations Are
Confirmation-Dependent
The recommendations included in this report – including any options or
alternatives – are confirmation-dependent. In other words, they are not
final, because the geotechnical engineer who developed them relied heavily
on judgement and opinion to do so. Your geotechnical engineer can finalize
the recommendations only after observing actual subsurface conditions
exposed during construction. If through observation your geotechnical
engineer confirms that the conditions assumed to exist actually do exist,
the recommendations can be relied upon, assuming no other changes have
occurred. The geotechnical engineer who prepared this report cannot assume
responsibility or liability for confirmation-dependent recommendations if you
fail to retain that engineer to perform construction observation.
This Report Could Be Misinterpreted
Other design professionals’ misinterpretation of geotechnical-
engineering reports has resulted in costly problems. Confront that risk
by having your geotechnical engineer serve as a continuing member of
the design team, to:
• confer with other design-team members;
• help develop specifications;
• review pertinent elements of other design professionals’ plans and
specifications; and
• be available whenever geotechnical-engineering guidance is needed.
You should also confront the risk of constructors misinterpreting this
report. Do so by retaining your geotechnical engineer to participate in
prebid and preconstruction conferences and to perform construction-
phase observations.
Give Constructors a Complete Report and Guidance
Some owners and design professionals mistakenly believe they can shift
unanticipated-subsurface-conditions liability to constructors by limiting
the information they provide for bid preparation. To help prevent
the costly, contentious problems this practice has caused, include the
complete geotechnical-engineering report, along with any attachments
or appendices, with your contract documents, but be certain to note
conspicuously that you’ve included the material for information purposes
only. To avoid misunderstanding, you may also want to note that
“informational purposes” means constructors have no right to rely on
the interpretations, opinions, conclusions, or recommendations in the
report. Be certain that constructors know they may learn about specific
project requirements, including options selected from the report, only
from the design drawings and specifications. Remind constructors
that they may perform their own studies if they want to, and be sure to
allow enough time to permit them to do so. Only then might you be in
a position to give constructors the information available to you, while
requiring them to at least share some of the financial responsibilities
stemming from unanticipated conditions. Conducting prebid and
preconstruction conferences can also be valuable in this respect.
Read Responsibility Provisions Closely
Some client representatives, design professionals, and constructors do
not realize that geotechnical engineering is far less exact than other
engineering disciplines. This happens in part because soil and rock on
project sites are typically heterogeneous and not manufactured materials
with well-defined engineering properties like steel and concrete. That
lack of understanding has nurtured unrealistic expectations that have
resulted in disappointments, delays, cost overruns, claims, and disputes.
To confront that risk, geotechnical engineers commonly include
explanatory provisions in their reports. Sometimes labeled “limitations,”
many of these provisions indicate where geotechnical engineers’
responsibilities begin and end, to help others recognize their own
responsibilities and risks. Read these provisions closely. Ask questions.
Your geotechnical engineer should respond fully and frankly.
Geoenvironmental Concerns Are Not Covered
The personnel, equipment, and techniques used to perform an
environmental study – e.g., a “phase-one” or “phase-two” environmental
site assessment – differ significantly from those used to perform a
geotechnical-engineering study. For that reason, a geotechnical-engineering
report does not usually provide environmental findings, conclusions, or
recommendations; e.g., about the likelihood of encountering underground
storage tanks or regulated contaminants. Unanticipated subsurface
environmental problems have led to project failures. If you have not
obtained your own environmental information about the project site,
ask your geotechnical consultant for a recommendation on how to find
environmental risk-management guidance.
Obtain Professional Assistance to Deal with
Moisture Infiltration and Mold
While your geotechnical engineer may have addressed groundwater,
water infiltration, or similar issues in this report, the engineer’s
services were not designed, conducted, or intended to prevent
migration of moisture – including water vapor – from the soil
through building slabs and walls and into the building interior, where
it can cause mold growth and material-performance deficiencies.
Accordingly, proper implementation of the geotechnical engineer’s
recommendations will not of itself be sufficient to prevent
moisture infiltration. Confront the risk of moisture infiltration by
including building-envelope or mold specialists on the design team.
Geotechnical engineers are not building-envelope or mold specialists.
Copyright 2019 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, in whole or in part, by any means whatsoever, is strictly
prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of
GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document or its wording as a complement to or as an element of a report of any kind.
Any other firm, individual, or other entity that so uses this document without being a GBA member could be committing negligent or intentional (fraudulent) misrepresentation.
Telephone: 301/565-2733
e-mail: info@geoprofessional.org www.geoprofessional.org
March 16, 2021
ES-7334
MainVue WA, LLC
1110 – 112th Avenue Northeast, Suite 202
Bellevue, Washington 98004
Attention: Ms. Lisa Cavell
Greetings, Ms. Cavell:
Earth Solutions NW, LLC (ESNW) is pleased to present this geotechnical report for the subject
site. Our investigation indicates the proposed short plat is feasible from a geotechnical standpoint
generally as planned. The site is underlain primarily by recessional outwash sand, with varying
fines content.
The proposed residential structures can be supported on conventional spread and continuous
footings bearing on undisturbed competent native soil, compacted native soil, or new structural
fill. We anticipate competent native soil suitable for support of foundations will be encountered
beginning at a depth of about two feet below existing grades. Where loose or unsuitable soil
conditions are encountered 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.
This report provides geotechnical analyses and recommendations for the proposed short plat.
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
Keven D. Hoffmann, P.E.
Senior Project Manager
15365 N.E. 90th Street, Suite 100 • Redmond, WA 98052 •(425) 449-4704 • FAX (425) 449-4711
Earth Solutions NW LLC
Geotechnical Engineering, Construction
Observation/Testing and Environmental Services
Earth Solutions NW, LLC
Table of Contents
ES-7334
PAGE
INTRODUCTION ................................................................................. 1
General..................................................................................... 1
Project Description ................................................................. 2
SITE CONDITIONS ............................................................................. 2
Surface ..................................................................................... 2
Subsurface .............................................................................. 2
Topsoil and Fill ............................................................. 3
Native Soil ..................................................................... 3
Geologic Setting ........................................................... 3
Groundwater ................................................................. 3
Critical Areas Review ............................................................. 3
DISCUSSION AND RECOMMENDATIONS ....................................... 4
General..................................................................................... 4
Site Preparation and Earthwork ............................................. 4
Temporary Erosion Control ......................................... 4
In-Situ and Imported Soil ............................................. 5
Structural Fill ................................................................ 5
Subgrade Preparation .................................................. 6
Excavations and Slopes .............................................. 6
Foundations ............................................................................ 6
Seismic Design ....................................................................... 7
Slab-on-Grade Floors ............................................................. 8
Retaining Walls ....................................................................... 8
Drainage................................................................................... 9
Infiltration Testing & Design ....................................... 9
Permeable Pavement Design ...................................... 10
Soil Properties for Groundwater Protection .............. 11
Drywells & Gravel-filled Trenches .............................. 11
Utility Support and Trench Backfill ....................................... 11
LIMITATIONS ...................................................................................... 12
Additional Services ................................................................. 12
Earth Solutions NW, LLC
Table of Contents
Cont’d
ES-7334
GRAPHICS
Plate 1 Vicinity Map
Plate 2 Test Pit Location Plan
Plate 3 Retaining Wall Drainage Detail
Plate 4 Footing Drain Detail
APPENDICES
Appendix A Subsurface Exploration
Test Pit Logs
Appendix B Laboratory Test Results
Earth Solutions NW, LLC
GEOTECHNICAL ENGINEERING STUDY
PROPOSED SHORT PLAT
1400 ABERDEEN AVENUE NORTHEAST
RENTON, WASHINGTON
ES-7334
INTRODUCTION
General
This geotechnical engineering study was prepared for the proposed short plat to be constructed
southeast of the intersection between Northeast 15th Street and Aberdeen Avenue Northeast, in
Renton, Washington. This report was prepared to aid the subject project with respect to the
currently proposed site layout. To prepare this report, the following scope items or services were
completed:
Subsurface exploration to characterize the soil and groundwater conditions.
In-situ infiltration testing.
Laboratory testing of representative soil samples collected on site.
Review of on-site critical areas.
Engineering analyses and recommendations for the proposed short plat.
The following documents and resources were reviewed as part of our report preparation:
Draft ALTA/NSPS Land Title Survey, prepared by Barghausen Consulting Engineers, Inc.,
dated November 21, 2020.
Geologic Map of King County, compiled by Derek B. Booth, Kathy G. Troost, and Aaron
P. Wisher, dated March 2007.
Online Web Soil Survey (WSS) resource, maintained by the Natural Resources
Conservation Service (NRCS) under the United States Department of Agriculture (USDA).
Liquefaction Susceptibility of King County (Map 11-5), endorsed by the King County Flood
Control District, dated May 2010.
Renton Municipal Code (RMC).
Online COR Maps Resource, maintained by the City of Renton.
2017 City of Renton Surface Water Design Manual.
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Earth Solutions NW, LLC
Project Description
We understand the existing residential structures will be removed, and a short plat will be
constructed. At the time this report was prepared, neither a formal site plan nor building load
values were available for review. However, we anticipate the proposed residential structures will
be two to three stories and constructed using relatively lightly loaded wood framing supported
atop conventional foundation systems. Based on our experience with similar developments, we
estimate wall loads of about 1 to 2 kips per linear foot and slab-on-grade loading of 150 pounds
per square foot (psf) will be incorporated into the final design.
Grade cuts and fills to establish individual-lot subgrade and finish grade elevations are expected
to be less than five feet. Retaining walls or rockeries may be constructed across the plat to
accommodate grade transitions, where necessary. A stormwater infiltration facility will likely be
constructed within the topographically low area of the site (southeastern corner).
If the above design assumptions either change or are incorrect, ESNW should be contacted to
review the recommendations provided in this report. ESNW should review final designs to verify
the geotechnical recommendations provided in this report have been incorporated into the plans.
SITE CONDITIONS
Surface
The subject site is located southeast of the intersection between Northeast 15 th Street and
Aberdeen Avenue Northeast, in Renton, Washington. The approximate location of the property
is illustrated on Plate 1 (Vicinity Map). The site is comprised of one tax parcel (King County
Parcel No. 334390-1680), totaling about 1.68 acres.
The site is currently occupied by a single-family residence and various outbuildings. The existing
topography descends generally from north to south, with an estimated 10 to 15 feet of elevation
change across the site. Vegetation consists mainly of lawn areas, with several scattered trees.
Subsurface
An ESNW representative observed, logged, and sampled six test pits on June 4, 2020. The test
pits were excavated at accessible locations within the property, using a trackhoe and operator
retained by our firm. 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 the test pit
locations were analyzed in general accordance with both Unified Soil Classification System
(USCS) and USDA methods and procedures.
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Earth Solutions NW, LLC
Topsoil and Fill
Topsoil was generally encountered within the upper six inches of existing grades at the test
locations. The topsoil was characterized by a dark brown color, the presence of fine organic
material, and small root intrusions.
Fill was encountered at TP-2 to a depth of roughly six inches below the existing ground surface
(bgs). The fill contained wire debris and trace root intrusions. Fill was not encountered elsewhere
on site.
Native Soil
Underneath the topsoil, the native soil consisted primarily of poorly graded sand with varying silt
content. Within roughly the upper two-and-one-half to five feet of existing grades, sand with
appreciable fines content (USCS: SP-SM or SM) was encountered. The native soil graded to
comparatively cleaner sand (USCS: SP) at depth, except at TP-4. The native deposits were
observed primarily in a “moist” or “moist to wet” condition at the time of the exploration. The
maximum exploration depth was roughly 18.5 feet bgs.
Geologic Setting
Based on our review of the referenced geologic map, the site is underlain by recessional outwash
(Qvr). Recessional outwash was deposited by glacial meltwater and is readily comprised of silt,
clay, sand, and gravel. The referenced WSS resource identifies Indianola loamy sand (Map Unit
Symbol: InC) across the site and surrounding area. The Indianola series was formed in eskers,
kames, and terraces.
Based on our field observations, the native soil encountered on site is generally consistent with
the information presented in the referenced geologic and soil mapping resources.
Groundwater
Groundwater was not encountered at the test locations during the June 2020 exploration.
Nonetheless, transient, perched groundwater seepage may develop seasonally and may be
encountered within site excavations depending on the time of year and extent of grading
activities. Seepage rates and elevations fluctuate depending on many factors, including
precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater
flow rates are higher during the winter, spring, and early summer months.
Critical Areas Review
To evaluate the presence of critical areas on site, we reviewed RMC Chapter 4-3 and the online
COR Maps resource. The RMC provides designation and definition criteria for identifying critical
areas and developing appropriate site development plans to limit adverse impacts to critical areas
both on and off site. Based on our review, the site is mapped within Zone 2 of a Wellhead
Protection Area (WPA). No other critical areas (including coalmine hazard, high erosion hazard,
flood hazard, landslide hazard, regulated slopes, and seismic hazard) are mapped on site or
immediately adjacent to the site.
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Earth Solutions NW, LLC
With respect to the mapped WPA, the proposal should comply with the requirements of RMC 4-
3-050, particularly concerning activities that are not permitted within a WPA. Residential plats
are commonly constructed within WPAs and critical aquifer recharge areas, including those that
incorporate stormwater infiltration into the final design. Based on our understanding of the
project, the proposal does not intend to incorporate activities that would adversely impact the
WPA or would otherwise be prohibited under the RMC. ESNW can provide additional consulting
and plan review services pertaining to the WPA, upon request.
DISCUSSION AND RECOMMENDATIONS
General
Based on the results of our investigation, construction of the proposed short plat is feasible from
a geotechnical standpoint. The primary geotechnical considerations associated with the
proposed development include site preparation and earthwork, suitability of on-site soil as
structural fill, subgrade preparation, temporary excavations, building foundations, and stormwater
facility construction.
Site Preparation and Earthwork
Site preparation activities should consist of installing temporary erosion control measures,
removing existing structural improvements, and performing site stripping within the designated
clearing limits. Subsequent earthwork activities will involve mass grading and utility installations.
Temporary Erosion Control
The following temporary erosion and sediment control (TESC) Best Management Practices
(BMPs) are offered:
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 a
stable access entrance surface. Placing geotextile fabric underneath the quarry spalls will
provide greater stability, if needed.
Silt fencing should be placed around appropriate portions of the site perimeter.
When not in use, soil stockpiles should be covered or otherwise protected to reduce the
potential for soil erosion, especially during periods of wet weather.
Temporary measures for controlling surface water runoff, such as interceptor trenches,
sumps, or interceptor swales, should be installed prior to beginning earthwork activities.
Dry soils disturbed during construction should be wetted to minimize dust.
When appropriate, permanent planting or hydroseeding will help to stabilize the site soil.
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Earth Solutions NW, LLC
Additional TESC BMPs, as specified by the project civil engineer and indicated on the plans,
should be incorporated into construction activities. TESC measures may be modified during
construction as site conditions require but should be discussed with and approved by the site
erosion control lead.
In-Situ and Imported Soil
On-site soil exposed during earthwork and grading activities will likely consist primarily of silty
sand and poorly graded sand with silt. The native soil possesses moderate moisture sensitivity
and will 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. If the on-site soil cannot be
successfully compacted, the use of an imported soil may be necessary.
In our opinion, a contingency should be provided in the project budget for export of soil that cannot
be successfully compacted as structural fill if grading activities take place during periods of rainfall
activity. We recommend avoiding construction-equipment tracking across the native soil and
generally active site work during periods of heavy rainfall; such disturbance has the potential to
degrade the native soil beyond a workable state.
Imported soil intended for use as structural fill should consist of a well-graded, granular soil with
a moisture content that is at (or slightly above) the optimum level. During wet weather conditions,
imported soil intended for use as structural fill should consist of a well-graded, granular soil with
a fines content of 5 percent or less (where the fines content is defined as the percent passing the
Number 200 sieve, based on the minus three-quarter-inch fraction).
Structural Fill
Structural fill is defined as compacted soil placed in foundation, slab-on-grade, roadway,
permanent slope, retaining wall, and utility trench backfill areas. Structural fill placed and
compacted during site grading activities should meet the following specifications and guidelines:
Structural fill material Granular soil*
Moisture content At or slightly above optimum †
Relative compaction (minimum) 95 percent (Modified Proctor)
Loose lift thickness (maximum) 12 inches
* Existing soil will not be suitable for use as structural fill unless at (or slightly above) the optimum moisture content
at the time of placement and compaction.
† Soil shall not be placed dry of optimum and should be evaluated by ESNW during construction.
With respect to underground utility installations and backfill, local jurisdictions may dictate the soil
type(s) and compaction requirements. Unsuitable material or debris must be removed from
structural areas if encountered.
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Earth Solutions NW, LLC
Subgrade Preparation
Following site stripping, ESNW should observe the subgrade to confirm soil conditions are as
anticipated and to provide supplementary recommendations for subgrade preparation, as
necessary. In general, foundation subgrade surfaces should be compacted in situ to a minimum
depth of one foot below the design subgrade elevation. Uniform compaction of the foundation
and slab subgrade areas will establish a relatively consistent subgrade condition below the
foundation and slab elements. Supplementary recommendations for subgrade improvement may
be provided at the time of construction and would likely include further mechanical compaction
or overexcavation and replacement with suitable structural fill.
Excavations and Slopes
Excavation activities are likely to expose medium dense silty sand and/or poorly graded sand.
Based on the soil conditions observed at the test pit locations, a maximum inclination of one-and-
one-half horizontal to one vertical (1.5H:1V) is recommended for temporary excavations and
slopes. Per Federal Occupation Safety and Health Administration and Washington Industrial
Safety and Health Act standards, the native soil classifies as Type C.
Steeper temporary inclinations with dense, undisturbed native soil (such as 1H:1V) may be
feasible but must be evaluated by ESNW on a case-by-case basis during construction.
Permanent slopes should be planted with vegetation to both enhance stability and minimize
erosion and should maintain a gradient of 2H:1V or flatter. An ESNW representative should
observe temporary and permanent slopes to confirm the slope inclinations are suitable for the
exposed soil conditions and to provide additional excavation and slope recommendations, as
necessary.
Foundations
The proposed residential structures can be supported on conventional spread and continuous
footings bearing on undisturbed competent native soil, compacted native soil, or new structural
fill. We anticipate competent native soil suitable for support of foundations will be encountered
beginning at a depth of about two feet bgs. Where loose or unsuitable soil conditions are
encountered 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.
Provided the structure 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
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Earth Solutions NW, LLC
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
settlement should occur during construction when dead loads are applied.
Seismic Design
The 2018 International Building Code (2018 IBC) recognizes the most recent edition of the
Minimum Design Loads for Buildings and Other Structures manual (ASCE 7-16) for seismic
design, specifically with respect to earthquake loads. Based on the soil conditions encountered
at the test pit locations, the parameters and values provided below are recommended for seismic
design per the 2018 IBC.
Parameter Value
Site Class D*
Mapped short period spectral response acceleration, S S (g) 1.437
Mapped 1-second period spectral response acceleration, S 1 (g) 0.492
Short period site coefficient, Fa 1.000
Long period site coefficient, Fv 1.808†
Adjusted short period spectral response acceleration, S MS (g) 1.437
Adjusted 1-second period spectral response acceleration, S M1 (g) 0.890†
Design short period spectral response acceleration, S DS (g) 0.958
Design 1-second period spectral response acceleration, S D1 (g) 0.593†
* Assumes medium dense native soil conditions, encountered to a maximum depth of 18.5 feet bgs during the June
2020 field exploration, remain medium dense (or dense) to at least 100 feet bgs.
† Values assume Fv may be determined using linear interpolation per Table 11.4-2 in ASCE 7-16.
As indicated in the table footnote, several of the seismic design values provided above are
dependent on the assumption that site-specific ground motion analysis (per Section 11.4.8 of
ASCE 7-16) will not be required for the subject project. ESNW recommends the validity of this
assumption be confirmed at the earliest available opportunity during the planning and early
design stages of the project. Further discussion between the project structural engineer, the
project owner, and ESNW may be prudent to determine the possible impacts to the structural
design due to increased earthquake load requirements under the 2018 IBC. ESNW can provide
additional consulting services to aid with design efforts, including supplementary geotechnical
and geophysical investigation, upon request.
Liquefaction is a phenomenon where saturated or loose soil suddenly loses internal strength and
behaves as a fluid. This behavior is in response to increased pore water pressures resulting from
an earthquake or another intense ground shaking. In our opinion, site susceptibility to liquefaction
may be considered low. The absence of a shallow groundwater table and the relatively dense
characteristics of the native soil were the primary bases for this opinion.
MainVue WA, LLC ES-7334
March 16, 2021 Page 8
Earth Solutions NW, LLC
Slab-on-Grade Floors
Slab-on-grade floors should be supported on firm and unyielding subgrades consisting of
competent native soil or at least 12 inches of new structural fill. Unstable or yielding subgrade
areas 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 each slab. The free-draining material should have 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). 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.
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. 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.
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. 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. If drainage is not provided, hydrostatic pressures
should be included in the wall design.
MainVue WA, LLC ES-7334
March 16, 2021 Page 9
Earth Solutions NW, LLC
Drainage
Discrete zones of perched groundwater seepage should be anticipated in 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 interceptor
trenches, interceptor swales, and sumps. ESNW should be consulted during preliminary grading
to both 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, foundation
drains should be installed along building perimeter footings. A typical foundation drain detail is
provided on Plate 4.
Infiltration Testing & Design
In accordance with the 2017 City of Renton Surface Water Design Manual (2017 RSWDM), one
small-scale Pilot Infiltration Test (PIT) was completed during the fieldwork. The PIT was
completed at TP-3 by excavating a test pit with a roughly three-foot by four-foot base infiltration
surface. The infiltration test was completed at a depth of about five feet bgs and followed the PIT
procedure prescribed in the 2017 RSWDM.
Based on the results of the PIT, the following design parameters are recommended:
Imeasured (measured infiltration rate; TP-3) 44 inches per hour (in/hr)
Ftesting 0.5 (small-scale PIT)
Fgeometry 0.75 (assumed)
Fplugging 0.9 (medium sand)
Idesign (calculated infiltration rate; TP-3) 14.8 in/hr
ESNW should be contacted to review stormwater management plans if infiltration is used for
design. Supplementary recommendations and/or testing may be necessary depending on the
size, depth, and siting of infiltration facilities.
Per pages 5-51 and 5-52 of the 2017 RSWDM, the native soil underneath an infiltration facility is
expected to inherently possess specific characteristics to minimize groundwater contamination.
The test results provided in the Soil Properties for Groundwater Protection section of this report
indicate the native soil in the proposed infiltration facility area does not meet the groundwater-
protection requirements, mainly due to suboptimal cation exchange capacity (CEC) values and
rapid infiltration rates. Accordingly, water quality treatment will need to be provided prior to
infiltration.
MainVue WA, LLC ES-7334
March 16, 2021 Page 10
Earth Solutions NW, LLC
Permeable Pavement Design
We understand permeable pavement may be incorporated into the final design. Because the
permeable roadway surface would be used for occasional emergency vehicle access, the design
must comply with H-20 loading specifications. Based on the soil conditions encountered at the
exploration locations, the following permeable pavement sections are offered to meet H-20
loading specifications from a geotechnical standpoint:
Permeable base course (for either permeable asphalt or permeable concrete)
o Minimum thickness: 12 inches
o Material: Permeable ballast per WSDOT 9-03.9(2), or approved equivalent
o Void content: 30 to 40 percent
Permeable asphalt
o Minimum thickness: 3 inches of permeable warm-mix asphalt (WMA) underlain by
4 inches of asphalt-treated permeable base
o Permeable hot-mix asphalt (HMA) is allowed in lieu of WMA, but WMA is preferred
Permeable concrete
o Minimum thickness: 6 inches
o Unit weight: 120 to 135 pcf
o Void content: 18 to 20 percent
Per page C-76 of the 2017 RSWDM, the native soil underneath the permeable pavement surface
must meet minimum CEC and organic content (OC) values of 8 meq/100 g and 1.0 percent,
respectively. The test results provided in the Soil Properties for Groundwater Protection section
of this report indicate the native soil expected to underlie permeable pavement areas will not
meet these minimum requirements. Accordingly, a six-inch sand layer must be included in the
design beneath the permeable pavement.
ESNW should be retained to observe pavement installation activities and provide applicable
consulting and testing services. Supplementary recommendations may be provided at the time
of construction, as needed.
MainVue WA, LLC ES-7334
March 16, 2021 Page 11
Earth Solutions NW, LLC
Soil Properties for Groundwater Protection
Representative soil samples were analyzed for CEC, OC, and grain size distribution. The results
of the relevant testing are summarized in the table below, and the laboratory data is provided in
Appendix B.
Test
Pit
Depth
(ft bgs)
CEC
(meq/100 g)
OC
(%)
% Passing
No. 4 Sieve
% Passing
No. 40 Sieve
% Passing
No. 100 Sieve
TP-1 2.0 5.6 2.5 99.8 67.0 10.3
TP-2 2.0 7.9 3.4 (not sieved)
TP-3 5.0 3.7 1.4 (not sieved)
TP-3 10.5 2.8 1.1 98.3 23.0 2.1
TP-4 2.5 5.4 2.5 (not sieved)
TP-5 3.0 5.1 2.0 100 82.5 24.4
TP-6 2.5 8.1 3.8 99.6 78.0 25.4
Drywells & Gravel-filled Trenches
Where drywells and/or gravel-filled trenches are incorporated into the final design, it is our opinion
the dominant soil grain size should be considered “medium sand”. Per page C-47 of the 2017
RSWDM, drywells must contain at least 90 cubic feet of gravel per 1,000 square feet of
impervious surface served. Gravel-filled trenches must be at least 30 feet in length per 1,000
square feet of impervious surface served. ESNW can provide additional consulting services and
recommendations for full infiltration BMPs, upon request.
Utility Support and Trench Backfill
In our opinion, the native soil will likely be suitable for support of utilities. Remedial measures
may be necessary in some areas to provide support for utilities, such as overexcavation and
replacement with structural fill and/or placement of geotextile fabric. Groundwater seepage may
be encountered within utility excavations, and caving of trench walls should be anticipated given
the cohesionless nature of site soils. Depending on the time of year and conditions encountered,
dewatering or temporary trench shoring may be necessary during utility excavation and
installation.
In general, the native soil may not be suitable for use as structural backfill throughout utility trench
excavations unless the soil is at (or slightly above) the optimum moisture content at the time of
placement and compaction. Moisture conditioning of the soil may be necessary at some locations
prior to use as structural fill. Each section of the utility lines must be adequately supported in
appropriate bedding material. Utility trench backfill should be placed and compacted to the
specifications of structural fill previously detailed in this report or to the applicable specifications
of the presiding jurisdiction.
MainVue WA, LLC ES-7334
March 16, 2021 Page 12
Earth Solutions NW, LLC
LIMITATIONS
This study has been prepared for the exclusive use of MainVue WA, LLC, and its representatives.
The recommendations and conclusions provided in the geotechnical engineering 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. No warranty, express or
implied, is made. Variations in the soil and groundwater conditions observed at the test pit
locations may exist and may not become evident until construction. ESNW should reevaluate
the conclusions provided in this geotechnical engineering study if variations are encountered.
Additional Services
ESNW should have an opportunity to review the final design with respect to the geotechnical
recommendations provided in this report. ESNW should also be retained to provided testing and
consultation services during construction.
Drwn.MRS
Checked KDH Date Mar.2021
Date 03/09/2021 Proj.No.7334
Plate 1
Earth Solutions NWLLC
Geotechnical Engineering,Construction
EarthSolutionsNWLLC
EarthSolutions
NW LLC Obser vation/Testing and Environmental Services
Vicinity Map
Vaughn Short Plat
Renton,Washington
NOTE:This plate may contain areas of color.ESNW cannot be
responsible for any subsequent misinterpretation of the information
resulting from black &white reproductions of this plate.
Reference:
King County,Washington
OpenStreetMap.org
NORTH
SITE
Renton
Plate
Proj.No.
Date
Checked By
Drwn.ByEarthSolutionsNWLLCGeotechnicalEngineering,ConstructionObservation/TestingandEnvironmentalServicesEarthSolutionsNWLLCEarthSolutionsNWLLCTestPitLocationPlanVaughnShortPlatRenton,WashingtonNORTH
NOT -TO -SCALE
NOTE:This plate may contain areas of color.ESNW cannot be
responsible for any subsequent misinterpretation of the information
resulting from black &white reproductions of this plate.
NOTE:The graphics shown on this plate are not intended for design
purposes or precise scale measurements,but only to illustrate the
approximate test locations relative to the approximate locations of
existing and /or proposed site features.The information illustrated
is largely based on data provided by the client at the time of our
study.ESNW cannot be responsible for subsequent design changes
or interpretation of the data by others.
LEGEND
Approximate Location of
ESNW Test Pit,Proj.No.
ES-7334,June 2020
Subject Site
Existing Building
TP-1
MRS
KDH
03/09/2021
7334
2
TP-1
TP-2
TP-3
TP-4
TP-5
TP-6ABERDEEN AVENUE N.E.N .E. 1 5 T H S TR EE T
300
290
300
290292
294
296
298
302
304
306
292
294
296
298
302
304
306
Drwn.MRS
Checked KDH Date Mar.2021
Date 03/09/2021 Proj.No.7334
Plate 3
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC Geotechnical Engineer ing,C onstr uction
Observation/Testing and Environmental Services
Retaining Wall Drainage Detail
Vaughn Short Plat
Renton,Washington
NOTES:
Free-draining Backfill should consist
of soil having less than 5 percent fines.
Percent passing No.4 sieve should be
25 to 75 percent.
Sheet Drain may be feasible in lieu
of Free-draining Backfill,per ESNW
recommendations.
Drain Pipe should consist of perforated,
rigid PVC Pipe surrounded with 1-inch
Drain Rock.
LEGEND:
Free-draining Structural Backfill
1-inch Drain Rock
18"Min.
Structural
Fill
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
SCHEMATIC ONLY -NOT TO SCALE
NOT A CONSTRUCTION DRAWING
Drwn.MRS
Checked KDH Date Mar.2021
Date 03/09/2021 Proj.No.7334
Plate 4
Earth Solutions NWLLC
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
EarthSolutionsNWLLC
EarthSolutions
NW LLC
Footing Drain Detail
Vaughn Short Plat
Renton,Washington
Slope
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
18"Min.
NOTES:
Do NOT tie roof downspouts
to Footing Drain.
Surface Seal to consist of
12"of less permeable,suitable
soil.Slope away from building.
LEGEND:
Surface Seal:native soil or
other low-permeability material.
1-inch Drain Rock
SCHEMATIC ONLY -NOT TO SCALE
NOT A CONSTRUCTION DRAW ING
Earth Solutions NW, LLC
Appendix A
Subsurface Exploration
Test Pit Logs
ES-7334
Subsurface conditions on site were explored on June 4, 2020. Six test pits were excavated using
a trackhoe and operator retained by our firm. 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 18.5 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.
GRAVEL
AND
GRAVELLY
SOILS
CLAYEY GRAVELS, GRAVEL - SAND -
CLAY MIXTURES
WELL-GRADED SANDS, GRAVELLY
SANDS, LITTLE OR NO FINES
POORLY-GRADED SANDS,
GRAVELLY SAND, LITTLE OR NO
FINES
SILTY SANDS, SAND - SILT
MIXTURES
CLAYEY SANDS, SAND - CLAY
MIXTURES
INORGANIC SILTS AND VERY FINE
SANDS, ROCK FLOUR, SILTY OR
CLAYEY FINE SANDS OR CLAYEY
SILTS WITH SLIGHT PLASTICITY
INORGANIC CLAYS OF LOW TO
MEDIUM PLASTICITY, GRAVELLY
CLAYS, SANDY CLAYS, SILTY CLAYS,
LEAN CLAYS
ORGANIC SILTS AND ORGANIC
SILTY CLAYS OF LOW PLASTICITY
INORGANIC SILTS, MICACEOUS OR
DIATOMACEOUS FINE SAND OR
SILTY SOILS
INORGANIC CLAYS OF HIGH
PLASTICITY
SILTS
AND
CLAYS
MORE THAN 50%
OF MATERIAL IS
LARGER THAN
NO. 200 SIEVE
SIZE
MORE THAN 50%
OF MATERIAL IS
SMALLER THAN
NO. 200 SIEVE
SIZE
MORE THAN 50%
OF COARSE
FRACTION
PASSING ON NO.
4 SIEVE
MORE THAN 50%
OF COARSE
FRACTION
RETAINED ON NO.
4 SIEVE
SOIL CLASSIFICATION CHART
(APPRECIABLE
AMOUNT OF FINES)
(APPRECIABLE
AMOUNT OF FINES)
(LITTLE OR NO FINES)
FINE
GRAINED
SOILS
SAND
AND
SANDY
SOILS
SILTS
AND
CLAYS
ORGANIC CLAYS OF MEDIUM TO
HIGH PLASTICITY, ORGANIC SILTS
PEAT, HUMUS, SWAMP SOILS WITH
HIGH ORGANIC CONTENTS
LETTERGRAPH
SYMBOLSMAJOR DIVISIONS
COARSE
GRAINED
SOILS
TYPICAL
DESCRIPTIONS
WELL-GRADED GRAVELS, GRAVEL -
SAND MIXTURES, LITTLE OR NO
FINES
POORLY-GRADED GRAVELS,
GRAVEL - SAND MIXTURES, LITTLE
OR NO FINES
SILTY GRAVELS, GRAVEL - SAND -
SILT MIXTURES
CLEAN
GRAVELS
GRAVELS WITH
FINES
CLEAN SANDS
(LITTLE OR NO FINES)
SANDS WITH
FINES
LIQUID LIMIT
LESS THAN 50
LIQUID LIMIT
GREATER THAN 50
HIGHLY ORGANIC SOILS
DUAL SYMBOLS are used to indicate borderline soil classifications.
The discussion in the text of this report is necessary for a proper understanding of the nature
of the material presented in the attached logs.
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
MH
CH
OH
PT
Earth Solutions NW LLC
292.5
290.5
275.5
MC = 9.5%
Fines = 5.0%
CEC =
5.6 meq/100g
OC = 2.5%
MC = 6.0%
Fines = 3.1%
MC = 4.7%
MC = 4.6%
MC = 4.9%
Fines = 2.1%
MC = 7.9%
MC = 6.4%
MC = 5.9%
TPSL
SP-
SM
SP
0.5
2.5
17.5
Dark brown TOPSOIL
Brown poorly graded SAND with silt, medium dense, moist
[USDA Classification: slightly gravelly SAND]
Gray poorly graded SAND, medium dense, moist
[USDA Classification: slightly gravelly SAND]
-notably coarser
[USDA Classification: slightly gravelly coarse SAND]
Test pit terminated at 17.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
NOTES Depth of Topsoil & Sod 6": grass
GROUND ELEVATION 293 ft
LOGGED BY KTK
EXCAVATION METHOD
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 6/4/20 COMPLETED 6/4/20
AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
PAGE 1 OF 1
TEST PIT NUMBER TP-1
PROJECT NUMBER ES-7334 PROJECT NAME Vaughn Short Plat
GENERAL BH / TP / WELL - 7334.GPJ - GINT STD US.GDT - 3/16/21Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
290.5
287.5
272.5
MC = 12.3%
CEC =
7.9 meq/100g
OC = 3.4%
MC = 6.6%
Fines = 4.5%
MC = 8.8%
MC = 8.0%
MC = 7.7%
MC = 7.5%
Fines = 3.5%
MC = 6.1%
TPSL
SP-
SM
SP
0.5
3.5
18.5
Dark brown TOPSOIL, trace roots to 1.5', wire debris (Fill)
Brown poorly graded SAND with silt, medium dense, moist to wet
Gray poorly graded SAND, medium dense, moist
[USDA Classification: slightly gravelly SAND]
-notably coarser
[USDA Classification: slightly gravelly SAND]
Test pit terminated at 18.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
NOTES Depth of Topsoil & Sod 6": grass
GROUND ELEVATION 291 ft
LOGGED BY KTK
EXCAVATION METHOD
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 6/4/20 COMPLETED 6/4/20
AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
PAGE 1 OF 1
TEST PIT NUMBER TP-2
PROJECT NUMBER ES-7334 PROJECT NAME Vaughn Short Plat
GENERAL BH / TP / WELL - 7334.GPJ - GINT STD US.GDT - 3/16/21Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
290.5
288.0
280.5
MC = 7.5%
CEC =
3.7 meq/100g
OC = 1.4%
MC = 16.5%
MC = 13.0%
Fines = 1.1%
CEC =
2.8 meq/100g
OC = 1.1%
TPSL
SP-
SM
SP
0.5
3.0
10.5
Dark brown TOPSOIL
Brown poorly graded SAND with silt, medium dense, moist
Gray poorly graded SAND, medium dense, moist
-infiltration test
-increased moisture content to BOH due to infiltration test
-notably coarser
[USDA Classification: slightly gravelly coarse SAND]
Test pit terminated at 10.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
NOTES Depth of Topsoil & Sod 6": grass
GROUND ELEVATION 291 ft
LOGGED BY KTK
EXCAVATION METHOD
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 6/4/20 COMPLETED 6/4/20
AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0
5
10
PAGE 1 OF 1
TEST PIT NUMBER TP-3
PROJECT NUMBER ES-7334 PROJECT NAME Vaughn Short Plat
GENERAL BH / TP / WELL - 7334.GPJ - GINT STD US.GDT - 3/16/21Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
302.5
298.5
293.5
MC = 12.0%
CEC =
5.4 meq/100g
OC = 2.5%
MC = 22.2%
MC = 20.9%
TPSL
SP-
SM
SM
0.5
4.5
9.5
Dark brown TOPSOIL
Brown poorly graded SAND with silt, medium dense, moist to wet
Brown silty SAND, medium dense, wet
-light iron oxide staining
-notably coarser
-becomes gray
Test pit terminated at 9.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
NOTES Depth of Topsoil & Sod 6": grass
GROUND ELEVATION 303 ft
LOGGED BY KTK
EXCAVATION METHOD
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 6/4/20 COMPLETED 6/4/20
AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0
5
PAGE 1 OF 1
TEST PIT NUMBER TP-4
PROJECT NUMBER ES-7334 PROJECT NAME Vaughn Short Plat
GENERAL BH / TP / WELL - 7334.GPJ - GINT STD US.GDT - 3/16/21Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
297.5
294.0
289.0
MC = 11.5%
Fines = 10.4%
CEC =
5.1 meq/100g
OC = 2.0%
MC = 8.8%
MC = 6.6%
TPSL
SP-
SM
SP
0.5
4.0
9.0
Dark brown TOPSOIL
Brown poorly graded SAND with silt, medium dense, moist to wet
[USDA Classification: slightly gravelly SAND]
Gray poorly graded SAND, medium dense, moist
Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
NOTES Depth of Topsoil & Sod 6": grass
GROUND ELEVATION 298 ft
LOGGED BY KTK
EXCAVATION METHOD
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 6/4/20 COMPLETED 6/4/20
AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0
5
PAGE 1 OF 1
TEST PIT NUMBER TP-5
PROJECT NUMBER ES-7334 PROJECT NAME Vaughn Short Plat
GENERAL BH / TP / WELL - 7334.GPJ - GINT STD US.GDT - 3/16/21Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
297.5
293.0
288.0
MC = 13.5%
Fines = 14.7%
CEC =
8.1 meq/100g
OC = 3.8%
MC = 5.9%
MC = 5.2%
TPSL
SM
SP
0.5
5.0
10.0
Dark brown TOPSOIL
Brown silty SAND, medium dense, moist to wet
[USDA Classification: slightly gravelly SAND]
Gray poorly graded SAND, medium dense, moist
Test pit terminated at 10.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
NOTES Depth of Topsoil & Sod 6": grass
GROUND ELEVATION 298 ft
LOGGED BY KTK
EXCAVATION METHOD
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY KDH
DATE STARTED 6/4/20 COMPLETED 6/4/20
AT TIME OF EXCAVATION ---
AT END OF EXCAVATION ---
AFTER EXCAVATION ---SAMPLE TYPENUMBERDEPTH(ft)0
5
10
PAGE 1 OF 1
TEST PIT NUMBER TP-6
PROJECT NUMBER ES-7334 PROJECT NAME Vaughn Short Plat
GENERAL BH / TP / WELL - 7334.GPJ - GINT STD US.GDT - 3/16/21Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
Earth Solutions NW, LLC
Appendix B
Laboratory Test Results
ES-7334
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
3
D100
140
Specimen Identification
1
fine
6
HYDROMETER
304
5.0
3.1
2.1
4.5
3.5
101/2
COBBLES
Specimen Identification
4
coarse
20 401.5 8 14
USDA: Brown Slightly Gravelly Sand. USCS: SP-SM.
USDA: Gray Slightly Gravelly Sand. USCS: SP.
USDA: Gray Slightly Gravelly Coarse Sand. USCS: SP.
USDA: Gray Slightly Gravelly Sand. USCS: SP.
USDA: Gray Slightly Gravelly Sand. USCS: SP.
6 60
PERCENT FINER BY WEIGHTD10
0.263
0.29
0.491
0.234
0.34
0.399
0.422
0.913
0.366
0.568
GRAIN SIZE DISTRIBUTION
100
2.77
2.38
3.29
2.92
2.69
LL
TP-01
TP-01
TP-01
TP-02
TP-02
0.144
0.177
0.278
0.125
0.211
3/4
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
GRAVEL SAND
9.5
9.5
9.5
4.75
9.5
%Silt
1.20
1.13
0.95
1.19
0.96
TP-01
TP-01
TP-01
TP-02
TP-02
2 2003
Cc CuClassification
%Clay
16
PID60 D30
coarse SILT OR CLAYfinemedium
GRAIN SIZE IN MILLIMETERS
3/8 50
2.0ft.
4.0ft.
12.0ft.
5.0ft.
16.0ft.
2.00ft.
4.00ft.
12.00ft.
5.00ft.
16.00ft.
PL
PROJECT NUMBER ES-7334 PROJECT NAME Vaughn Short Plat
GRAIN SIZE USDA ES-7334 VAUGHN SP.GPJ GINT US LAB.GDT 10/22/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
3
D100
140
Specimen Identification
1
fine
6
HYDROMETER
304
1.1
10.4
14.7
101/2
COBBLES
Specimen Identification
4
coarse
20 401.5 8 14
USDA: Gray Slightly Gravelly Coarse Sand. USCS: SP.
USDA: Brown Slightly Gravelly Sand. USCS: SP-SM.
USDA: Brown Slightly Gravelly Sand. USCS: SM.
6 60
PERCENT FINER BY WEIGHTD10
0.45
0.165
0.166
0.846
0.278
0.314
GRAIN SIZE DISTRIBUTION
100
3.03
3.78
LL
TP-03
TP-05
TP-06
0.279
3/4
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
GRAVEL SAND
9.5
4.75
9.5
%Silt
0.86
1.33
TP-03
TP-05
TP-06
2 2003
Cc CuClassification
%Clay
16
PID60 D30
coarse SILT OR CLAYfinemedium
GRAIN SIZE IN MILLIMETERS
3/8 50
10.5ft.
3.0ft.
2.5ft.
10.50ft.
3.00ft.
2.50ft.
PL
PROJECT NUMBER ES-7334 PROJECT NAME Vaughn Short Plat
GRAIN SIZE USDA ES-7334 VAUGHN SP.GPJ GINT US LAB.GDT 10/22/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
Am Test Inc.
13600 NE 126TH PL
Suite C
Kirkland, WA 98034
(425) 885-1664
www.amtestlab.com
Professional
Analytical
Services
ANALYSIS REPORT
EARTH SOLUTIONS NW Date Received: 10/19/20
15365 NE 90TH ST Date Reported: 10/27/20
REDMOND, WA 98052
Attention: KEVEN HOFFMANN
Project Name: VAUGHN SP
Project #: ES-7334
All results reported on an as received basis.
_________________________________________________________________________________________________
AMTEST Identification Number 20-A017147
Client Identification TP 01, 2'
Sampling Date 06/04/20
Conventionals
PARAMETER RESULT UNITS Q D.L.METHOD ANALYST DATE
Cation Exchange Capacity 5.6 meq/100g 0.5 SW-846 9081 JDR 10/27/20
Miscellaneous
PARAMETER RESULT UNITS Q D.L.METHOD ANLST DATE
Organic Matter 2.5 %SM 2540G DM 10/23/20
_________________________________________________________________________________________________
AMTEST Identification Number 20-A017148
Client Identification TP 02, 2'
Sampling Date 06/04/20
Conventionals
PARAMETER RESULT UNITS Q D.L.METHOD ANALYST DATE
Cation Exchange Capacity 7.9 meq/100g 0.5 SW-846 9081 JDR 10/27/20
EARTH SOLUTIONS NW
Project Name: VAUGHN SP
AmTest ID: 20-A017148
Miscellaneous
PARAMETER RESULT UNITS Q D.L.METHOD ANLST DATE
Organic Matter 3.4 %SM 2540G DM 10/23/20
_________________________________________________________________________________________________
AMTEST Identification Number 20-A017149
Client Identification TP 03, 5'
Sampling Date 06/04/20
Conventionals
PARAMETER RESULT UNITS Q D.L.METHOD ANALYST DATE
Cation Exchange Capacity 3.7 meq/100g 0.5 SW-846 9081 JDR 10/27/20
Miscellaneous
PARAMETER RESULT UNITS Q D.L.METHOD ANLST DATE
Organic Matter 1.4 %SM 2540G DM 10/23/20
_________________________________________________________________________________________________
AMTEST Identification Number 20-A017150
Client Identification TP 03, 10.5'
Sampling Date 06/04/20
Conventionals
PARAMETER RESULT UNITS Q D.L.METHOD ANALYST DATE
Cation Exchange Capacity 2.8 meq/100g 0.5 SW-846 9081 JDR 10/27/20
Miscellaneous
PARAMETER RESULT UNITS Q D.L.METHOD ANLST DATE
Organic Matter 1.1 %SM 2540G DM 10/23/20
EARTH SOLUTIONS NW
Project Name: VAUGHN SP
AmTest ID: 20-A017151
_________________________________________________________________________________________________
AMTEST Identification Number 20-A017151
Client Identification TP 04, 2.5'
Sampling Date 06/04/20
Conventionals
PARAMETER RESULT UNITS Q D.L.METHOD ANALYST DATE
Cation Exchange Capacity 5.4 meq/100g 0.5 SW-846 9081 JDR 10/27/20
Miscellaneous
PARAMETER RESULT UNITS Q D.L.METHOD ANLST DATE
Organic Matter 2.5 %SM 2540G DM 10/23/20
_________________________________________________________________________________________________
AMTEST Identification Number 20-A017152
Client Identification TP 05, 3'
Sampling Date 06/04/20
Conventionals
PARAMETER RESULT UNITS Q D.L.METHOD ANALYST DATE
Cation Exchange Capacity 5.1 meq/100g 0.5 SW-846 9081 JDR 10/27/20
Miscellaneous
PARAMETER RESULT UNITS Q D.L.METHOD ANLST DATE
Organic Matter 2.0 %SM 2540G DM 10/23/20
EARTH SOLUTIONS NW
Project Name: VAUGHN SP
AmTest ID: 20-A017153
_________________________________________________________________________________________________
AMTEST Identification Number 20-A017153
Client Identification TP 06, 2.5'
Sampling Date 06/04/20
Conventionals
PARAMETER RESULT UNITS Q D.L.METHOD ANALYST DATE
Cation Exchange Capacity 8.1 meq/100g 0.5 SW-846 9081 JDR 10/27/20
Miscellaneous
PARAMETER RESULT UNITS Q D.L.METHOD ANLST DATE
Organic Matter 3.8 %SM 2540G DM 10/23/20
_________________________________
Kathy Fugiel
President
Earth Solutions NW, LLC
Report Distribution
ES-7334
EMAIL ONLY MainVue WA, LLC
1110 – 112th Avenue Northeast, Suite 202
Bellevue, Washington 98004
Attention: Ms. Lisa Cavell
EMAIL ONLY Barghausen Consulting Engineers, Inc.
18215 – 72nd Avenue South
Kent, Washington 98032
Attention: Mr. Barry Talkington, P.E.
Mr. Tom Barghausen, P.E.