22-104098-Woodlands Lot 8 - Geotechnical (Soils) Report 9-8-2241 1
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PROPOSED WOODLANDS AT REDONDO CREEK -
RESIDENTIAL DEVELOPMENT
3023X - 20T" AVENUE SOUTH
FEDERAL WAY, WASHINGTON
ES-6637
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RMJ HOLDINGS, LLC
October 3, 2019
Updated March 25, 2020
J
Scott S. Riegel, L.G., L.E.G.
Senior Project Manager
R• CAM
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FGIS25/2020
Kyle R. Campbell, P.E.
Principal Engineer
GEOTECHNICAL ENGINEERING STUDY
PROPOSED WOODLANDS AT REDONDO CREEK
RESIDENTIAL DEVELOPMENT
3023X — 20TH AVENUE SOUTH
FEDERAL WAY, WASHINGTON
ES-6637
Earth Solutions NW, LLC
15365 Northeast 90t" Street, Suite 100
Redmond, Washington 98052
Phone: 425-449-4704 1 Fax: 425-449-4711
www.earthsolutionsnw.com
Geotechnical-Engineering Report
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.
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.
October 3, 2019
Updated March 25, 2020
ES-6637
RMJ Holdings, LLC
9675 Southeast 36th Street, Suite 105
Mercer Island, Washington 98040
Attention: Mr. Dmitriy Mayzlin
Dear Mr. Mayzlin:
Earth
Solutions
NWLLC
Earth Solutions NW LLC
Geotechnical Engineering, Construction
Observation/Testing and Environmental Services
Earth Solutions NW, LLC (ESNW) is pleased to present this report in support of a planned
residential development in Federal Way, Washington". Based on the results of our investigation,
the proposed project is feasible from a geotechnical standpoint. Our study indicates the site is
underlain primarily by glacial till deposits. During our subsurface exploration completed on April
12, 2019, groundwater seepage was not encountered at the test pit locations. However, it is our
opinion the contractor should be prepared to respond to discrete zones of groundwater seepage
during construction.
The proposed residential structures should be constructed on conventional continuous and
spread footing foundations bearing upon competent native soil, recompacted native soil, or new
structural fill placed directly on a competent native soil subgrade. In general, competent native
soil suitable for support of foundations will likely be encountered within the upper two to four feet
of existing grades. Where loose or unsuitable soil conditions are exposed at foundation subgrade
elevations, compaction of soils to the specifications of structural fill, or overexcavation and
replacement with suitable structural fill, will be necessary.
Based on our field observations of the glacial till deposits, infiltration is not feasible from a
geotechnical standpoint. The majority of glacial till deposits observed at the test pit locations
were medium dense to dense and contained significant silt content and are considered
impervious for practicable stormwater design purposes. Conventional methods of stormwater
management, such as on -site detention, dispersion, and/or connecting to existing stormwater
collection systems, may prove more practical.
15365 N.E. 90th Street, Suite 100 0 Redmond, WA 98052 0 (425) 449-4704 9 FAX (425) 449-4711
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
Pertinent geotechnical recommendations are
opportunity to be of service to you on this project.
this geotechnical engineering study, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
Scott S. Riegel, L.G., L.E.G.
Senior Project Manager
ES-6637
Executive Summary — Page 2
provided in this study. We appreciate the
If you have questions regarding the content of
Earth Solutions NW. LLC
Table of Contents
ES-6637
PAGE
INTRODUCTION.................................................................................
General.....................................................................................
Project Description................................................................. 2
SITE CONDITIONS............................................................................. 2
Surface..................................................................................... 2
Subsurface.............................................................................. 2
Topsoil and Fill............................................................. 3
NativeSoil........................................................... 3
Geologic Setting........................................................... 3
Groundwater................................................................. 3
Environmentally Critical Areas .............................................. 3
Erosion Hazard Areas .................................................. 4
DISCUSSION AND RECOMMENDATIONS .......................................
4
General.....................................................................................
4
Site Preparation and Earthwork .............................................
5
Temporary Erosion Control .........................................
5
Stripping.......................................................................
5
Excavations and Slopes ..............................................
6
In -situ and Imported Soils ...........................................
6
Structural Fill................................................................
7
Foundations............................................................................
7
SeismicDesign.......................................................................
7
Slab -on -Grade Floors.............................................................
8
RetainingWalls.......................................................................
8
Rockeries......................................................................
9
Drainage...................................................................................
9
Preliminary Infiltration Feasibility ...............................
9
Utility Support and Trench Backfill.......................................
9
Preliminary Pavement Sections .............................................
10
LIMITATIONS...................................................................................... 11
Additional Services................................................................. 11
Earth Solutions NW. LLC
GRAPHICS
Plate 1
Plate 2
Plate 3
Plate 4
APPENDICES
Appendix A
Appendix B
Table of Contents
Cont'd
ES-6637
Vicinity Map
Test Pit Location Plan
Retaining Wall Drainage Detail
Footing Drain Detail
Subsurface Exploration
Test Pit Logs
Laboratory Test Results
Earth Solutions NW. LLC
GEOTECHNICAL ENGINEERING STUDY
PROPOSED WOODLANDS AT REDONDO CREEK
RESIDENTIAL DEVELOPMENT
3023X — 20TH AVENUE SOUTH
FEDERAL WAY, WASHINGTON
ES-6637
INTRODUCTION
General
This geotechnical engineering study (study) was prepared for the proposed residential
development to be constructed northwest of the intersection between South 304th Street and 20th
Avenue South, in Federal Way, Washington. The purpose of this study was to develop
geotechnical recommendations for the proposed project. The scope of services for completing
this study included the following:
• Excavation of test pits for purposes of characterizing site soil conditions;
• Laboratory testing of soil samples collected at the test pit locations;
• Engineering analyses, and;
• Preparation of this report.
The following documents and maps were reviewed as part of preparing this study:
• Preliminary Grading Plan, Sheet PP-04, prepared by ESM Consulting Engineers, LLC,
dated March 12, 2020;
• Soils and Slope Exhibit prepared by ESM Consulting Engineers, LLC, dated 2018;
• Lidar-revised Geologic Map of the Poverty Bay 7.5' Quadrangle, King and Pierce Counties,
Washington, prepared by R.W. Tabor et al., dated 2014;
• King County Liquefaction Susceptibility Map, endorsed by the King County Flood Control
District, dated May 2010;
• Critical Areas Map, prepared by the City of Federal Way, Washington, dated May 2016;
• Chapter 19.145 of the Federal Way Revised Code (FWRC), and;
• Online Web Soil Survey (WSS) resource, provided by the United States Department of
Agriculture (USDA), Natural Resources Conservation Service.
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
Project Description
ES-6637
Page 2
The preliminary site layout indicates that 68 new single-family residences and associated
infrastructure improvements will be constructed. Level lots will be used where existing grades
are relatively level and daylight basements will be used where gradients are sloped. We
anticipate retaining walls and/or rockeries will likely be incorporated into final designs to
accommodate grade transitions, where necessary.
At the time of report submission, specific building load and grading plans were not available for
review; however, we anticipate the proposed structures will be two to three stories in height and
constructed utilizing relatively lightly loaded wood framing supported on a conventional
foundation system. Perimeter footing loads will likely be 1 to 2 kips per lineal foot. Slab -on -grade
loading is anticipated to be approximately 150 pounds per square foot (psf).
The proposed development will incorporate a stormwater detention pond in the northwest corner
of the site.
If the above design assumptions are incorrect or change, ESNW should be contacted to review
the recommendations provided in this report. ESNW should review final designs to confirm that
our geotechnical recommendations have been incorporated into the plans.
SITE CONDITIONS
Surface
The subject site is located northwest of the intersection between South 304th Street and 20th
Avenue South, in Federal Way, Washington. The approximate location of the property is
illustrated on Plate 1 (Vicinity Map). The property is comprised of two tax parcels (King County
Parcel Nos. 042104-9012 and -9221) totaling about 22.2 acres. The site is bordered to the north
by single-family residences, to the east by single-family residences and 20th Avenue South, to
the south by South 304th Street, and to the west by wetland buffer area and Highway 99. The
site is currently vacant and vegetated with moderate to heavy forest and undergrowth. The site
topography is characterized by a moderate westward facing slope spanning the property that
descends to a natural stream area. The slope grade reaches approximately 15 percent or slightly
greater near the wetland buffer where a stream is located.
Subsurface
A representative of ESNW observed, logged, and sampled eight test pits, excavated at accessible
locations within the site boundaries, on April 12, 2019 using a trackhoe and operator retained by
ESNW. The test pits were completed for purposes of assessing soil and groundwater conditions
within areas proposed for new development. The approximate locations of the test pits are
illustrated on the Test Pit Location Plan (Plate 2). Please refer to the test pit logs provided in
Appendix A for a more detailed description of subsurface conditions. Representative samples
collected at the test pit locations were analyzed in general accordance with Unified Soil
Classification System (USCS) and United States Department of Agriculture (USDA) methods and
procedures.
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
Topsoil and Fill
ES-6637
Page 3
Topsoil was encountered at most test pits and extended to depths of about 6 to 12 inches. The
topsoil was characterized by the observed dark brown hue, the presence of fine organics, and
moderate root intrusions.
Fill was not encountered during our exploration. We do not anticipate fill to be encountered at
the subject property. If fill is encountered during construction, ESNW can evaluate fill deposits,
as necessary.
Native Soil
Underlying topsoil and fill, native soils were encountered primarily as silty sand with gravel,
(USCS: SM). The native deposits were generally medium dense to very dense. Soils were
generally encountered in a dense, unweathered condition beginning at about three and one-half
feet Native soils were primarily encountered in a damp condition and extended to the maximum
exploration depth of approximately 16 feet below the existing ground surface (bgs).
Geologic Setting
The referenced geologic map resource identifies Vashon glacial till (Qvt) deposits as the primary
native soil unit underlying the subject site. As reported on the geologic map resource, the glacial
till consists of a nonsorted mixture of silt, sand, pebbles, cobbles, and boulders and is referred to
locally as "hardpan." The till was deposited directly from the glacier as it advanced over bedrock
and older Quaternary sediment. The referenced WSS resource identifies Alderwood series soils
with varying slopes (Map Unit Symbols: AgB, AgC, and AgD) as the primary soil units underlying
the subject site. Seattle muck deposits (Map Unit: Sk) is mapped within the wetland buffer area.
The Alderwood series was formed in glacial till and is located along ridges, upland plateau areas
and hills. Based on our field observations, on -site native soils are generally consistent with glacial
till (Qvt) deposits.
Groundwater
During our subsurface exploration completed on April 12, 2019, groundwater seepage was not
encountered below existing grades. However, it is our opinion the contractor should anticipate,
and be prepared to respond to, localized zones of perched groundwater seepage during
construction. Groundwater seepage is common within relatively permeable lenses and/or at the
transition between weathered and unweathered dense to very dense native soil deposits. It
should be noted that 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 wet season (October through April).
Environmentally Critical Areas
Based on our review of the Federal Way Revised Code (FWRC) Section 19.145 -
Environmentally Critical Areas and the referenced critical areas map, the site is mapped within a
geologically hazardous area (erosion). Based on the available map data and field observations,
erosion hazard areas present on the subject site are delineated on Plate 2.
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
Erosion Hazard Areas
ES-6637
Page 4
The central portion of the site contains slopes that are inclined at 15 percent or greater and are
underlain by Alderwood series (AgD) soils. These conditions meet the criteria for erosion hazard
as defined by the FWRC. There are no buffers associated with erosion hazard areas per FWRE
Section 19.145.240 and protection mechanisms are related to temporary and permanent erosion
control measures. The current conceptual site plan indicates that some areas designated as
erosion hazards will be developed. In our opinion, temporary erosion control measures should
be designed to prevent silt -laden water to be discharged from the construction area. Erosion
control measures are discussed later in this report and provide general recommendations for
protecting site and surrounding areas from erosion related impacts. In any case, erosion control
measures should be actively maintained to ensure proper performance. Specific
recommendations for erosion control are provided later in this report. Provided the
recommendations in this report are incorporated into the plans, in our opinion, the proposed
project will not decrease slope stability on adjacent properties. The stormwater management
plans should ensure that discharge does not exceed pre -development conditions or applicable
regulatory conditions. The temporary and permanent erosion control measures shall ensure that
the adjacent wetland/stream corridor is adequately protected from erosion or related instability.
DISCUSSION AND RECOMMENDATIONS
General
Based on the results of our investigation, in our opinion, construction of the proposed residential
development is feasible from a geotechnical standpoint. The primary geotechnical
considerations associated with the proposed development include foundation support, slab -on -
grade subgrade support, the suitability of using on site soils as structural fill, and grading activities
within erosion hazard areas.
The proposed residential structures may be constructed on conventional continuous and spread
footing foundations bearing upon competent native soil, recompacted native soil, or new
structural fill placed directly on competent native soils. In general, competent native soil suitable
for support of foundations will likely be encountered within the upper two to four feet of existing
grades. Where loose or unsuitable soil conditions are exposed at foundation subgrade
elevations, compaction of soils to the specifications of structural fill, or overexcavation and
replacement with suitable structural fill, will be necessary.
Due to the dense condition and relatively high percentage of fines of the glacial till deposits across
the site, infiltration is not feasible from a geotechnical standpoint. We understand that a
stormwater detention pond will be constructed adjacent to the wetland buffer area.
This study has been prepared for the exclusive use of RMJ Holdings, LLC and their
representatives. A warranty is neither expressed nor implied. This study has been prepared in
a manner consistent with the level of care and skill ordinarily exercised by other members of the
profession currently practicing under similar conditions in this area.
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
Site Preparation and Earthwork
ES-6637
Page 5
Initial site preparation activities will consist of installing temporary erosion control measures,
establishing grading limits, performing clearing and site stripping, and removing structural
improvements. Subsequent earthwork activities will involve site grading and related
infrastructure improvements.
Temporary Erosion Control
The following temporary erosion control measures are offered:
• Temporary construction entrances and drive lanes, consisting of at least 12 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 the site perimeter.
• When not in use, soil stockpiles should be covered or otherwise protected.
• Temporary measures for controlling surface water runoff, such as interceptor trenches,
sumps, or swales, should be installed prior to beginning earthwork activities.
• Dry soils disturbed during construction should be wetted to minimize dust and airborne soil
erosion.
Additional Best Management Practices (BMPs), as specified by the project civil engineer and
indicated on the plans, should be incorporated into construction activities. Temporary erosion
control measures must be actively monitored and may be modified during construction as site
conditions require, to ensure proper performance.
Stripping
Topsoil was encountered within the upper 6 to 12 inches and root intrusions generally extended
about 6 inches below the topsoil. The organic -rich topsoil should be stripped and segregated
into a stockpile for later use on site or to export. The material remaining immediately below the
topsoil may have some root zones and will likely be variable in composition, density, and/or
moisture content. The material exposed after initial topsoil stripping will likely not be suitable for
direct structural support and will likely need to either be compacted in place or stripped and
stockpiled for reuse as fill; depending on the time of year stripping occurs, the soil exposed below
the topsoil may be too wet to compact adequately and may need to be aerated or otherwise
treated. ESNW should observe initial stripping activities to provide recommendations regarding
stripping depths and material suitability.
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
Excavations and Slopes
ES-6637
Page 6
Excavation activities are likely to expose both medium dense soil (within the upper two to four
feet bgs) and dense soil at depth. Based on the soil conditions observed at the test pit locations,
the following allowable temporary slope inclinations, as a function of horizontal to vertical (H:V)
inclination, may be used. The applicable Federal Occupation Safety and Health Administration
(OSHA) and Washington Industrial Safety and Health Act (WISHA) soil classifications are also
provided:
• Loose to medium dense soil 1.5H:1 V (Type C)
• Areas containing groundwater seepage 1.5H:1V (Type C)
• Medium dense or dense glacial till 1 H:1 V (Type B)
Steeper inclinations within native, undisturbed soils may be considered, and must be
subsequently designed, by ESNW at the time of construction. Permanent slopes should be
planted with vegetation to enhance stability and to minimize erosion, and should maintain a
gradient of 2H:1 V or flatter. The presence of perched groundwater may cause localized
sloughing of temporary slopes due to excess seepage forces. An ESNW representative should
observe temporary and permanent slopes to confirm the slope inclinations are suitable for the
exposed soil conditions and to provide additional excavation and slope recommendations, as
necessary. If the recommended temporary slope inclinations cannot be achieved, temporary
shoring may be necessary to support excavations.
In -situ and Imported Soils
On -site soils are moisture sensitive, and successful use of on -site soils as structural fill will largely
be dictated by the moisture content at the time of placement and compaction. Remedial
measures, such as soil aeration and/or cement treatment (where approved by the local
jurisdiction or utility district), may be necessary as part of site grading and earthwork activities. If
the on -site soils 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, particularly if grading activities take
place during periods of extended rainfall activity. In general, soils with fines contents greater than
5 percent typically degrade rapidly when exposed to periods of rainfall.
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).
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
Structural Fill
ES-6637
Page 7
Structural fill is defined as compacted soil placed in foundation, slab -on -grade, roadway,
permanent slope, utility trench, and retaining wall backfill areas. Soils placed in structural areas
should be placed in loose lifts of 12 inches or less and compacted to a relative compaction of 95
percent, based on the laboratory maximum dry density as determined by the Modified Proctor
Method (ASTM D1557). More stringent compaction specifications may be required for utility
trench backfill zones depending on the responsible utility district or jurisdiction.
Foundations
The proposed residential structures can be constructed on conventional continuous and spread
footing foundations bearing upon competent native soil, recompacted native soil, or new
structural fill. In general, competent native soil suitable for support of foundations will likely be
encountered within the upper two to four feet of existing grades. Where loose or unsuitable soil
conditions are exposed at foundation subgrade elevations, compaction of soils to the
specifications of structural fill, or overexcavation and replacement with suitable structural fill, will
be necessary. Provided the foundations will be supported as prescribed, the following
parameters may be used for design:
• Allowable soil bearing capacity 2,500 psf
• Passive earth pressure 300 pcf (equivalent fluid)
• Coefficient of friction 0.40
A one-third increase in the allowable soil bearing capacity may be assumed for short-term wind
and seismic loading conditions. The above passive pressure and friction values include a factor -
of -safety of 1.5. With structural loading as expected, total settlement in the range of one inch and
differential settlement of about one-half inch is anticipated. The majority of settlement should
occur during construction, as dead loads are applied.
Seismic Design
The 2015 International Building Code recognizes the American Society of Civil Engineers (ASCE)
for seismic site class definitions. Based on the soil conditions encountered at the test pit
locations, in accordance with Table 20.3-1 of the ASCE Minimum Design Loads for Buildings and
Other Structures manual, Site Class D should be used for design.
The referenced liquefaction susceptibility map indicates the subject site maintains "very low to
low" liquefaction susceptibility. Liquefaction is a phenomenon where saturated and loose soils
suddenly lose internal strength in response to increased pore water pressures resulting from an
earthquake or other intense ground shaking. In our opinion, native site soils are not susceptible
to liquefaction. The relative densities of the native soils and the absence of a uniformly
established, shallow groundwater table were the primary bases for this consideration.
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
Slab -on -Grade Floors
ES-6637
Page 8
Slab -on -grade floors for the proposed residential structures should be supported on firm and
unyielding subgrades comprised of competent native soil, compacted structural fill, or new
structural fill. Unstable or yielding areas of the subgrades 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 slabs -on -grade. 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 vapor barriers below the slabs should be considered. If a vapor barrier
is to be utilized, it should be a material specifically designed for use as a vapor barrier and should
be installed in accordance with the specifications of the manufacturer.
Retaining Walls
Retaining walls must be designed to resist earth pressures and applicable surcharge loads. The
following parameters may be used for design:
• Active earth pressure (yielding condition)
At -rest earth pressure (restrained condition)
• Traffic surcharge (passenger vehicles)
Passive earth pressure
• Coefficient of friction
• Seismic surcharge
* Where applicable
** Where H equals the retained height (in feet)
35 pcf (equivalent fluid)
55 pcf
70 psf (rectangular distribution)*
300 pcf (equivalent fluid)
6H psf**
The above design parameters are based on a level backfill condition and level grade at the wall
toe. Revised design values will be necessary if sloping grades are to be used above or below
retaining walls. Additional surcharge loading from adjacent foundations, sloped backfill, or other
relevant loads should be included in the retaining wall design, where applicable.
Retaining walls should be backfilled with free -draining material or suitable sheet drainage 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 can consist of a less permeable soil, if desired. A perforated
drainpipe should be placed along the base of the wall and connected to an approved discharge
location. 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.
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
Rockeries
ES-6637
Page 9
Based on review of the referenced grading plan, rockeries will be used to accommodate grade
changes across the site. Final rockery heights and alignments were not completed at the time of
this report, but the conceptual configuration shown on the grading plan is generally acceptable
from a geotechnical standpoint. Most interior rockeries will be of low height; however, a taller
rockery is proposed along the east project area. This rockery, while taller than prescriptive code
allows, will reduce the overall grading required to construct the building pads and site
infrastructure. In our opinion, the proposed walls including the taller wall proposed along the east
project area will not increase impacts to adjacent sensitive areas. ESNW can provide a formal
rockery design, upon request.
Drainage
Discrete zones of perched groundwater seepage should be anticipated in site excavations
depending on the time of year grading operations take place, particularly within deeper
excavations for utilities. Temporary measures to control surface water runoff and groundwater
during construction would likely involve interceptor trenches and sumps. ESNW should be
consulted during preliminary grading to identify areas of seepage and to provide
recommendations to reduce the potential for instability related to seepage effects.
Finish grades must be designed to direct surface water away from the new structures and/or
slopes. Water must not be allowed to pond adjacent to the new structure and/or slopes. In our
opinion, foundation drains should be installed along the building perimeter footings. A typical
foundation drain detail is provided on Plate 4.
Preliminary Infiltration Feasibility
As indicated in the Subsurface section of this study, native soils encountered during our fieldwork
were characterized primarily as medium dense to very dense glacial till deposits. Given the
compact nature and relatively high fines contents of the glacial till across the site, infiltration is
not feasible from a geotechnical standpoint. Conventional methods of stormwater management,
such as on -site detention and connecting to existing stormwater collection systems, may prove
more practical.
Utility Support and Trench Backfill
In our opinion, native soils may generally be suitable for support of utilities. Both organic -rich soil
and fill are considered unsuitable for direct support of utilities and should be removed at utility
grades, if encountered. Remedial measures, such as overexcavation and replacement with
structural fill and/or installation of geotextile fabric, may be necessary in some areas to provide
support for utilities. Groundwater may be encountered within deeper utility excavations, and
caving of trench walls may occur where groundwater is encountered. Temporary construction
dewatering, as well as temporary trench shoring, may be necessary during utility excavation and
installation as conditions warrant.
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
ES-6637
Page 10
In general, native soils may not be suitable for use as structural backfill throughout utility trench
excavations, unless the soils are at (or slightly above) the optimum moisture content at the time
of placement and compaction. Structural trench backfill should not be placed dry of the optimum
moisture content. Each section of the site utility lines must be adequately supported in
appropriate bedding material. Utility trench backfill should be placed and compacted to the
specifications of structural fill as previously detailed in this report, or to the applicable
specifications of the City of Federal Way or other responsible jurisdiction or agency.
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 subgrade areas may still exist after base grading activities. Areas
containing unsuitable or yielding subgrade conditions will require remedial measures, such as
overexcavation and/or placement of thicker crushed rock or structural fill sections, prior to
pavement. Cement treatment of the subgrade soil can also be considered for stabilizing
pavement subgrade areas if allowed by local jurisdictions.
For lightly loaded pavement areas subjected primarily to passenger vehicles, the following
preliminary pavement sections may be considered:
• A minimum of two inches of hot mix asphalt (HMA) placed over four inches of crushed
rock base (CRB), or;
• A minimum of two inches of HMA placed over three inches of asphalt treated base (ATB).
Heavier traffic areas generally require thicker pavement sections depending on site usage,
pavement life expectancy, and site traffic. For preliminary design purposes, the following
pavement sections for occasional truck traffic areas may be considered:
• Three inches of HMA placed over six inches of crushed rock base (CRB), or;
• Three inches of HMA placed over four -and -one-half inches of ATB.
The HMA, ATB and CRB materials should conform to WSDOT specifications. All soil base
material should be compacted to a relative compaction of 95 percent, based on the laboratory
maximum dry density as determined by ASTM D1557. Final pavement design recommendations,
including recommendations for heavy traffic areas, access roads, and frontage improvement
areas, can be provided once final traffic loading has been determined. Road standards utilized
by the City of Federal Way may supersede the recommendations provided in this report.
Earth Solutions NW. LLC
RMJ Holdings, LLC
October 3, 2019
Updated March 25, 2020
LIMITATIONS
ES-6637
Page 11
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 test pit locations may
exist and may not become evident until construction. ESNW should reevaluate the conclusions
provided in this study if variations are encountered.
Additional Services
ESNW should have an opportunity to review final project plans with respect to the geotechnical
recommendations provided in this report. ESNW should also be retained to provide testing and
consultation services during construction.
Earth Solutions NW. LLC
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Reference: NORTH
Earth Earth Solutions NWLLC
Solution
King County, Washington
NW LLC IF GeotechnicdEnjneering, Construction
Map 745
O''- ' and Environmental
By The Thomas Guide
Rand McNally
Vicinity Map
32nd Edition
Danilchik Property
Federal Way, Washington
NOTE: This plate may contain areas of color. ESNW cannot be
responsible for any subsequent misinterpretation of the information
Drwn. CAM
Date 04/25/2019
Proj. No. 6637
resulting from black & white reproductions of this plate.
Checked SES
Date April 2019
Plate 1
c
510 —�----I---_-500
�Qo �U)480 LEGEND o - -7I62TP' 1
-
I I Approximate Location of �
TP1 App a
�� I I I I — ■ — ESNW Test Pit, Proj. No. J
ES-6637 April 2019
l,J TP-8 I,� 170 E2
\ y 1J�� =� i — �i'�Subject Site m m
5101 \i-i-I ='I TF�-5
TRILL
15% + Slope in AgD Soils
2■— i
Am B460
500
440
_ \_ _
AgD ----- �� \ `� '� ` �' �' 7T1470
_09
-=r�----=-�f--
-
i h` i I
.000,
� i
y - � I
\ AmB - �- _----------------------------- ,
� 0 75 150 300
I
/ / 1 "=150' _
� I Scale in Feet :
Storm Pond ' '
Ag D I y '
�+
I
45� �1 / I SkWWI Cc
AgC 000, NOTE: The graphics shown on this plate are not intended for design s
purposes or precise scale measurements, but only to illustrate the
4441 _ --- I approximate test locations relative to the approximate locations of
-------------------------r—=--__—_--_r-� _ existing and /or proposed site features. The information illustrated
PACIFIC HIGHWAY S.-------- is largely based on data provided by the client at the time of our Drwn. By
study. ESNW cannot be responsible for subsequent design changes MRS
or interpretation of the data by others.
Checked By
SSR
NOTE: This plate may contain areas of color. ESNW cannot be Date
responsible for any subsequent misinterpretation of the information 09/30/2019
resulting from black & white reproductions of this plate.
Proj. No.
6637
Plate
2
18" Min.
00 0� o oUoo
00
00 oo00�0 �o 0000 o B
00 o o 0 o00 0
0 o o° o °�` o° 'o o
00
o oa0 0 o�00 0 oo 8 o
00 ° o 0 0 o
o 0 o O o 0
oo
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0 0 o 0 o 0 0 o 0
0 0 0 o0 00C 0 o 0
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o 0 0 o ° �r.'r ?�0
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:
Qo0o O
0 o0 00 Free -draining Structural Backfill
1-inch Drain Rock
.}.r.r.r.
Structural
Fill
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
SCHEMATIC ONLY - NOT TO SCALE
NOT A CONSTRUCTION DRAWING
Retaining Wall Drainage Detail
Danilchik Property
Federal Way, Washington
Drwn. CAM Date 04/26/2019 Proj. No. 6637
Checked SES Date April 2019 Plate 3
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
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
r�r�r�r�r
SCHEMATIC ONLY - NOT TO SCALE
NOT A CONSTRUCTION DRAWING
Earth
Solutions
N W uc
Footing Drain Detail
Danilchik Property
Federal Way, Washington
Drwn. CAM Date 04/26/2019 Proj. No. 6637
Checked SES Date April 2019 Plate 4
Appendix A
Subsurface Exploration
Test Pit Logs
ES-6637
Subsurface conditions at the subject site were explored on April 12, 2019 by excavating eight
test pits 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 maximum exploration depth was approximately 16 feet bgs.
The final logs represent the interpretations of the field logs and the results of laboratory analyses.
The stratification lines on the logs represent the approximate boundaries between soil types. In
actuality, the transitions may be more gradual.
Earth Solutions NW. LLC
Earth Solutions NWLLC
SOIL CLASSIFICATION CHART
MAJOR DIVISIONS
SYMBOLS
TYPICAL
DESCRIPTIONS
GRAPH
LETTER
GRAVEL
AND
CLEAN
GRAVELS
''�
I.�•� �
� � A.
GW
WELL -GRADED GRAVELS, GRAVEL -
SAND MIXTURES, LITTLE OR NO
FINES
GRAVELLY
SOILS
(LITTLE OR NO FINES)
° �° o �°
o pOo p
Q Q oQ
GP
POORLY -GRADED GRAVELS,
GRAVEL - SAND MIXTURES, LITTLE
OR NO FINES
COARSE
GRAINED
SOILS
MORE THAN 50%
OF COARSE
GRAVELS WITH
FINES
o
Q
0
°°
o
'
p
GM
SILTY GRAVELS, GRAVEL - SAND -
SILT MIXTURES
FRACTION
RETAINED ON NO.
4 SIEVE
(APPRECIABLE
AMOUNT OF FINES)
�±�
V
CLAYEY GRAVELS, GRAVEL - SAND -
CLAY MIXTURES
SAND
AND
CLEAN SANDS
SW
WELL -GRADED SANDS, GRAVELLY
SANDS, LITTLE OR NO FINES
MORE THAN 50%
OF MATERIAL IS
LARGER THAN
SANDY
NO. 200 SIEVE
SIZE
SOILS
(LITTLE OR NO FINES)
::.
SP
POORLY -GRADED SANDS,
GRAVELLY SAND, LITTLE OR NO
FINES
SANDS WITH
FINES
c•M
c
SILTY SANDS, SAND - SILT
MIXTURES
MORE THAN 50%
OF COARSE
FRACTION
PASSING ON NO.
4 SIEVE
(APPRECIABLE
AMOUNT OF FINES)
cC
�7
CLAYEY SANDS, SAND - CLAY
MIXTURES
INORGANIC SILTS AND VERY FINE
ML
SANDS, ROCK FLOUR, SILTY OR
CLAYEY FINE SANDS OR CLAYEY
SILTS WITH SLIGHT PLASTICITY
FINE
GRAINED
SOILS
SILTS
AND LIQUID LIMIT
LESS THAN 50
CLAYS
CL
INORGANIC CLAYS OF LOW TO
MEDIUM PLASTICITY, GRAVELLY
CLAYS, SANDY CLAYS, SILTY CLAYS,
LEAN CLAYS
OL
ORGANIC SILTS AND ORGANIC
SILTY CLAYS OF LOW PLASTICITY
MORE THAN 50%
OF MATERIAL IS
SMALLER THAN
NO. 200 SIEVE
MH
INORGANIC SILTS, MICACEOUS OR
DIATOMACEOUS FINE SAND OR
SILTY SOILS
SIZE
SILTS
AND LIQUID LIMIT
CLAYS GREATER THAN 50
CI I
INORGANIC CLAYS OF HIGH
PLASTICITY
OH
ORGANIC CLAYS OF MEDIUM TO
HIGH PLASTICITY, ORGANIC SILTS
HIGHLY ORGANIC SOILS
'/ ` 1/ 01/ 01/ N
\„ \„ „
0 0„
PT
PEAT, HUMUS, SWAMP SOILS WITH
HIGH ORGANIC CONTENTS
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.
y Earth Solutions NW, LLC TEST PIT NUMBER TP-1
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-6637 PROJECT NAME Danilchik Property
DATE STARTED 4/12/19 COMPLETED 4/12/19 GROUND ELEVATION 516 ft TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION ---
LOGGED BY SES CHECKED BY SSR AT END OF EXCAVATION ---
NOTES Depth of Topsoil & Sod 12": duff AFTER EXCAVATION -
L
=
}�
H L
U
2
w
Lu
g
TESTS
Uj
Q O
MATERIAL DESCRIPTION
❑
a- Z
�
W
U
Q
U
0
Dark brown TOPSOIL, root intrusions to 1'
TPSL ,'/. i.i
1.0
515.0
Brown silty SAND with gravel, medium dense, damp
MC = 9.40%
-becomes gray, dense to very dense (unweathered till)
Fines = 26.10%
[USDA Classification: very gravelly sandy LOAM]
5
SM
MC = 6.20%
becomes very dense
10
MC = 5.60% 11.5
504.5
Test pit terminated at 11.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
y Earth Solutions NW, LLC TEST PIT NUMBER TP-2
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-6637 PROJECT NAME Danilchik Property
DATE STARTED 4/12/19 COMPLETED 4/12/19 GROUND ELEVATION 504 ft TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION ---
LOGGED BY SES CHECKED BY SSR AT END OF EXCAVATION ---
NOTES Depth of Topsoil & Sod 12": duff AFTER EXCAVATION -
L
=
}�
H L
U
2
w
Lu
g
TESTS
Uj
Q O
MATERIAL DESCRIPTION
❑
a- Z
�
W
U
Q
U
0
TOPSOIL
TPSL ,'/. i.i
1.0
503.0
Brown silty SAND with gravel, medium dense, moist
MC = 10.20%
-becomes gray, dense to very dense, damp
MC = 4.80%
5 SM
MC = 9.90%
MC = 7.000/, 9.0
[USDA Classification: very gravelly LOAM] 495.0
Fines = 34.10%
Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
y Earth Solutions NW, LLC TEST PIT NUMBER TP-3
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-6637 PROJECT NAME Danilchik Property
DATE STARTED 4/12/19 COMPLETED 4/12/19 GROUND ELEVATION 470 ft TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION ---
LOGGED BY SES CHECKED BY SSR AT END OF EXCAVATION ---
NOTES Depth of Topsoil & Sod 12" AFTER EXCAVATION -
L
=
}�
H L
U
2
w
g
TESTS
0- O
MATERIAL DESCRIPTION
❑
�Z
0
U
Q
U
0
TOPSOIL
TPSL ,'/. i.i
1.0
469.0
Brown silty SAND with gravel, medium dense, damp
MC = 9.10%
becomes gray, dense to very dense
5 SM
becomes moist
MC = 11.90% 9'0
461.0
Test pit terminated at 9.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
y Earth Solutions NW, LLC TEST PIT NUMBER TP-4
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-6637 PROJECT NAME Danilchik Property
DATE STARTED 4/12/19 COMPLETED 4/12/19 GROUND ELEVATION 470 ft TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION ---
LOGGED BY SES CHECKED BY SSR AT END OF EXCAVATION ---
NOTES Depth of Topsoil & Sod 12": duff AFTER EXCAVATION -
L
=
}�
H L
U
2
w
Lu
g
TESTS
Uj
Q O
MATERIAL DESCRIPTION
❑
a- Z
�
W
U
Q
U
0
TOPSOIL
TPSL ,'/. i.i
1.0
469.0
Brown silty SAND, medium dense, moist
MC = 11.40%
-becomes gray, dense to very dense, damp
MC = 9.50%
5
SM
increasing silt
10
increasing sand
MC = 4.20%
15
MC = 7.200/( . 15.5
[USDA Classification: very gravelly sandy LOAM] 454.5
Fines = 19.40%
Test pit terminated at 15.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
y Earth Solutions NW, LLC TEST PIT NUMBER TP-5
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-6637 PROJECT NAME Danilchik Property
DATE STARTED 4/12/19 COMPLETED 4/12/19 GROUND ELEVATION 502 ft TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION --
LOGGED BY SES CHECKED BY SSR AT END OF EXCAVATION --
NOTES Depth of Topsoil & Sod 12": duff AFTER EXCAVATION -
L
=
}�
H L
U
2
w
g
TESTS
0- O
MATERIAL DESCRIPTION
❑
�Z
0
U
Q
U
0
Dark brown TOPSOIL, minimal root intrusions
TPSL ,'/. i.i
1.0
501.0
Brown silty SAND with gravel, medium dense, damp
MC = 13.00%
becomes gray, dense to very dense
5
SM
MC = 11.20%
10
MC = 8.10% 12.5
489.5
Test pit terminated at 12.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
y Earth Solutions NW, LLC TEST PIT NUMBER TP-6
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-6637 PROJECT NAME Danilchik Property
DATE STARTED 4/12/19 COMPLETED 4/12/19 GROUND ELEVATION 512 ft TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION ---
LOGGED BY SES CHECKED BY SSR AT END OF EXCAVATION ---
NOTES Surface Conditions: gravel fill AFTER EXCAVATION -
L
=
}�
H L
U
2
w
Lu
g
TESTS
Uj
Q O
MATERIAL DESCRIPTION
❑
2 Z
U
Q
U
0
GP 0.5
Gray poorly graded GRAVEL (Fill) 511.5
Brown silty SAND with gravel, medium dense, moist
MC = 11.70%
-becomes gray, dense to very dense
5
SM
MC = 12.30%
-becomes very dense
Fines = 49.20%
[USDA Classification: gravelly LOAM]
10
-becomes damp
MC = 7.40% 14.0
498.0
Test pit terminated at 14.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
y Earth Solutions NW, LLC TEST PIT NUMBER TP-7
15365 N.E. 90th Street, Suite 100 PAGE 1 OF 1
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-6637 PROJECT NAME Danilchik Property
DATE STARTED 4/12/19 COMPLETED 4/12/19 GROUND ELEVATION 492 ft TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION --
LOGGED BY SES CHECKED BY SSR AT END OF EXCAVATION --
NOTES Depth of Topsoil & Sod 6": duff AFTER EXCAVATION -
L
=
}�
H L
U
2
w
Lu
g
TESTS
Uj
Q O
MATERIAL DESCRIPTION
❑
2 Z
U
Q
U
0
TPSL �.. 0.5
TOPSOIL 491.5
Brown silty SAND with gravel, medium dense, wet
MC = 19.80%
-becomes gray, dense to very dense, moist
5
SM
10 MC = 10.00% 10.0
482.0
Test pit terminated at 10.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
y Earth Solutions NW, LLC TEST PIT NUMBER TP-8
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052 PAGE 1 OF 1
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-6637 PROJECT NAME Danilchik Property
DATE STARTED 4/16/19 COMPLETED 4/16/19 GROUND ELEVATION 490 ft TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
EXCAVATION METHOD AT TIME OF EXCAVATION ---
LOGGED BY SES CHECKED BY SSR AT END OF EXCAVATION ---
NOTES Depth of Topsoil & Sod 12" AFTER EXCAVATION -
L
=
}�
H L
U
2
w
g
TESTS
0- O
MATERIAL DESCRIPTION
❑
�Z
0
U
Q
U
0
Dark brown TOPSOIL, root intrusions to 1.5'
TPSL
,'/. i.i
1.0 489.0
Brown silty SAND with gravel, medium dense, damp
becomes gray, dense to very dense
5
SM :.
10
MC = 10.30%
15
MC = 8.70% 16.0 [USDA Classification: slightly gravelly loamy SAND] 474.0
Fines = 15.80% Test pit terminated at 16.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
Appendix B
Laboratory Test Results
ES-6637
Earth Solutions NW. LLC
Earth Solutions NW
1805 - 136th Place N. E., Suite 201
milm- I'm
Bellevue, Washington 98005
loan Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-6637
U.S. SIEVE OPENING IN INCHES
GRAIN SIZE DISTRIBUTION
PROJECT NAME Danilchik Property
U.S. SIEVE NUMBERS I HYDROMETER
GRAIN SIZE IN MILLIMETERS
GRAVEL.
SAND
COBBLES
SILT OR
CLAY
coarse
fine
coarse medium fine
Specimen Identification
a
Classification
Cc
Cu
•
TP-01
3.50ft.
USDA: Brown Very Gravelly Sandy Loam. USCS: SM with Gravel.
a m
TP-02
9.00%
USDA: Gray Very Gravelly Loam. USCS: SM with Gravel.
a ♦
TP-04
15.50ft.
USDA: Gray Very Gravelly Sandy Loam. USCS: SM with Gravel.
*
TP-06
8.00ft.
USDA: Gray Gravelly Loam. USCS: SM.
W. o
TP-08
16.00ft.
USDA: Gray Slightly Gravelly Loamy Sand. USCS: SM.
Specimen Identification
D100
D60
D30
D10
LL
PL
PI
%Silt %clay
L 0
TP-01
3.5%
19
2.539
0.121
26.1
m
n
TP-02
9.Oft.
19
1.373
34.1
L ♦
V
TP-04
15.5ft.
3.989
0.273
19.4
z *
TP-06
8.Oft.
�19
0.172
49.2
O
TP-08
16.Oft.
9.5
1 0.212
0.123
15.8
Report Distribution
ES-6637
EMAIL ONLY RMJ Holdings, LLC
9675 Southeast 36' Street, Suite 105
Mercer Island, Washington 98040
Attention: Mr. Dmitriy Mayzlin
EMAIL ONLY ESM Consulting Engineers, Inc.
33400 — 8t" Avenue South, Suite 205
Federal Way, Washington 98003
Attention: Ms. Savanna Nagorski
Earth Solutions NW. LLC