HomeMy WebLinkAboutRS_Geotechnical_Report_20210521_v1.pdfSECTION 37
GEOTECHNICAL REPORT
EarthSolutionsNWLLC
EarthSolutions
NW LLC
15365 N.E. 90th Street, Suite 100 Redmond, WA98052
(425) 449-4704 Fax (425) 449-4711
www.earthsolutionsnw.com
Geotechnical Engineering
Construction Observation/Testing
Environmental Services
UPDATED
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RENTON APARTMENTS
615 AND 617 WILLIAMS AVENUE SOUTH
RENTON, WASHINGTON
ES-5946.03
PREPARED FOR
GMD DEVELOPMENT, LLC
June 10, 2020
_________________________
Adam Z. Shier, L.G.
Project Geologist
_________________________
Kyle R. Campbell, P.E.
Principal Engineer
UPDATED
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RENTON APARTMENTS
615 AND 617 WILLIAMS AVENUE SOUTH
RENTON, WASHINGTON
ES-5946.03
Earth Solutions NW, LLC
15365 Northeast 90th Street, Suite 100
Redmond, Washington 98052
Phone: 425-449-4704 | Fax: 425-449-4711
www.earthsolutionsnw.com
06/10/2020
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
June 10, 2020
ES-5946.03
GMD Development, LLC
520 Pike Street, Suite 1010
Seattle, Washington 98101
Attention: Mr. Thomas Geffner
Dear Mr. Geffner:
Earth Solutions NW, LLC (ESNW) is pleased to present this report titled “Updated Geotechnical
Engineering Study, Proposed Renton Apartments, 615 and 617 Williams Avenue South, Renton,
Washington”. This report was updated to reference the most current plans and provide additional
subsurface exploration.
Based on the conditions observed during our fieldwork, the site is underlain primarily by a
relatively thick layer of very loose to medium dense alluvial sediments consisting predominately
of silt and sand layers. The seasonal groundwater level was observed at depths of about six to
nine feet below existing grades. Groundwater levels fluctuate and may become shallower during
the wetter winter months.
Based on the results of our study, the proposed apartment building should be supported by a pile
foundation system advanced through the loose soils to bear on firm native soils, or on
conventional shallow foundations after completion of a ground improvement program (rammed
aggregate piers, etc.). Recommendations for foundation design and other geotechnical
recommendations are provided in this study.
The opportunity to be of service to you is appreciated. If you have any questions regarding the
content of this geotechnical engineering study, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
Adam Z. Shier, L.G.
Project Geologist
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-5946.03
PAGE
INTRODUCTION ................................................................................. 1
General..................................................................................... 1
Project Description ................................................................. 2
SITE CONDITIONS ............................................................................. 2
Surface ..................................................................................... 2
Subsurface .............................................................................. 2
Groundwater ................................................................. 3
Geologically Hazardous Areas .............................................. 3
Seismic Hazard Areas .................................................. 4
Coal Mine Hazard Areas .............................................. 4
DISCUSSION AND RECOMMENDATIONS ....................................... 4
General..................................................................................... 4
Site Preparation and Earthwork ............................................. 5
Foundations ............................................................................ 6
Ground Improvement ................................................... 6
Pile Foundations .......................................................... 6
Building Slabs ......................................................................... 7
Retaining Walls ....................................................................... 7
Seismic Considerations ......................................................... 8
Drainage................................................................................... 8
Utility Trench Backfill ............................................................. 8
Pavement Sections ................................................................. 9
LIMITATIONS ...................................................................................... 9
Additional Services ................................................................. 9
Earth Solutions NW, LLC
Table of Contents
Cont’d
ES-5946.03
GRAPHICS
Plate 1 Vicinity Map
Plate 2 Subsurface Exploration Plan
Plate 3 Retaining Wall Drainage Detail
Plate 4 Footing Drain Detail
APPENDICES
Appendix A Subsurface Exploration
Boring and Test Pit Logs
Appendix B Laboratory Test Results
Earth Solutions NW, LLC
UPDATED
GEOTECHNICAL ENGINEERING STUDY
PROPOSED RENTON APARTMENTS
615 AND 617 WILLIAMS AVENUE SOUTH
RENTON, WASHINGTON
ES-5946.03
INTRODUCTION
General
This updated geotechnical engineering study was prepared for the proposed apartment building
to be constructed at 615 and 617 Williams Avenue in Renton, Washington. The purpose of this
study was to prepare geotechnical recommendations for the proposed development. Our scope
of services for completing this geotechnical engineering study included the following:
Subsurface exploration and laboratory testing of soil samples obtained during subsurface
exploration;
Engineering analyses, and;
Preparation of this report.
As part of our report preparation, the following documents were reviewed:
Architectural Site Plan, prepared by Studio19 Architects;
Geologic Map of the Renton Quadrangle, King County, Washington, 1965, by D.R.
Mullineaux;
Geologic Structure Map of Renton Coal Mine, 1920, by Watkins Evans;
Amendments to the King County Surface Water Design Manual, February 2010, Provided
by the City of Renton, and;
The Natural Resources Conservation Service Web Soil Survey (WSS).
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Project Description
We understand the site will be developed with an apartment building and associated
improvements. A preliminary site layout plan was available to us at the time of this report
preparation, and we anticipate the building will be six stories in height with one level of concrete
and five levels of wood frame supported on a post-tensioned concrete slab. No grading plans
were available at the time of writing this report; however, we anticipate the parking area will have
a finish floor elevation matching the existing grade. The building will likely incorporate a post-
tensioned slab configuration. If grades will be raised more than one foot, the recommendations
herein must be re-evaluated by ESNW.
We anticipate foundation loads will be on the order of 4 to 6 kips per lineal foot for continuous
footings, column loads on the order of 300 to 500 kips and slab-on-grade loading will likely be on
the order of 150 pounds per square foot (psf). A preload program to reduce settlement on site
will likely be necessary due to the soil conditions encountered.
If the above design assumptions are incorrect or change, ESNW should be contacted to review
the recommendations in this report. ESNW should review the final design to verify that our
geotechnical recommendations have been incorporated.
SITE CONDITIONS
Surface
The site is located at 615 and 617 Williams Avenue in Renton, Washington. The site is irregular
in shape and is bordered to the north and west by mixed commercial and residential properties,
to the south by South Grady Way and to the east by Williams Avenue South. The 617 address
is currently occupied by a billboard, and the 615 address contains a single-family residence. The
overall site topography is relatively flat with little discernible elevation change and vegetation
consists primarily of field grass with sparse trees near Williams Avenue. The limits of the property
are approximately delineated on the Subsurface Exploration Plan (Plate 2).
Subsurface
Two test pits were excavated across accessible areas of the site for purposes of assessing soil
conditions and characterizing the site soils on March 20, 2018. A boring was completed on April
5, 2018 to further classify the site soils. Three additional borings (B-101, B-102, and B-103) were
advanced across the subject site on May 22, 2020 as part of this updated geotechnical
engineering study. Please refer to the test pit and boring logs provided in Appendix A for a more
detailed description of the subsurface conditions. Additionally, two groundwater wells were
installed at boring locations B-101 and B-102 to monitor groundwater throughout the 2020-2021
winter season.
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Earth Solutions NW, LLC
At our test sites, a relatively deep topsoil layer was encountered extending up to about two feet
below existing grades. The topsoil was characterized by a dark brown color and organic content.
fill was not encountered; however, fill may be present in areas where former structures were
removed. Underlying the topsoil, very loose to medium dense alluvial and floodplain deposits
consisting of non-plastic silt (ML), silty fine sand (SM) and sand (SP, SP-SM) were encountered
extending to the maximum exploration depth of 46.5 feet. A thin layer of peat (PT) was
encountered at boring location B-1 and B-101 from about 21 to 21.5 feet below existing grade.
Soil conditions improved to a medium dense state at depths of about 20 to 30 feet. The
referenced geologic map of the area identifies alluvial soil deposits modified by widespread
artificial fill throughout the site and surrounding areas. The referenced WSS resource indicates
the site is underlain predominantly by Urban land (Ur) soils. This soil unit is used in areas of
extensive grading.
The soil conditions observed at our test sites generally correlates with historic fill underlain by
alluvial deposition.
Groundwater
The seasonal groundwater table was observed at an average depth of about six to nine feet
below existing grades during our fieldwork (March and April 2018) which occurred during a record
rainfall season and between 9 to 10 feet during our May 2020 fieldwork. However, the seasonal
high groundwater elevation may rise to a shallower depth than the elevation observed during our
fieldwork depending on the seasonal rainfall.
It should be noted that groundwater elevations fluctuate depending on many factors, including
precipitation duration and intensity, the time of year, and soil conditions. In general, groundwater
levels are generally higher during the wetter, winter months. With respect to the proposed
development activities, groundwater should be expected in site excavations, particularly
underground utility and vault excavations. We understand underground building levels are not
planned as part of the proposed construction. In this respect, extensive measures for controlling
groundwater and temporary dewatering are not anticipated. However, temporary dewatering of
underground utility excavations should be expected throughout some areas of the site. Flowing
sand condition may be encountered depending on the time of year deeper excavations occur.
Additionally, two groundwater wells were installed at boring locations B-101 and B-102 to monitor
groundwater throughout the 2020-2021 winter season.
Geologically Hazardous Areas
As part of this study, the site and proposed development areas were evaluated for the presence
of geologically hazardous areas. As part of our evaluation, Chapter 4-3-050 of the Renton
Municipal Code was reviewed.
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Earth Solutions NW, LLC
Seismic Hazard Areas
Liquefaction is a phenomenon where saturated or loose soils suddenly lose internal strength in
response to increased pore water pressures resulting from an earthquake or other intense ground
shaking. The liquefaction susceptibility for the subject site in the current configuration is high.
We used the Liquefy5 computer program to assess the overall susceptibility of the site to
liquefaction and associated settlement resulting from the maximum credible earthquake event for
this area. We determined the peak ground acceleration (PGA) using the USGS online calculation
program that provides current information for a particular address location. Using this resource,
a design PGA of 0.4g was used. The computer model predicted significant settlement may occur
from liquefaction occurring after the site is subjected to the design PGA. We used this
assessment to aid in developing foundation support recommendations that would adequately
mitigate differential settlement and maintain adequate levels of life-safety subsequent to a design
earthquake event. We would expect total settlements in the range of five to ten inches and
differential settlements of between two to four inches may result from strong seismic shaking to
occur within the existing soils.
Providing a uniform subgrade and foundation support using either piles or a ground improvement
program will reduce the potential for differential settlement that may result from a strong seismic
event. With foundation support as recommended in this report, we do not anticipate life-safety
will be compromised resulting from liquefaction; however, damage should be expected from
seismic shaking.
Coal Mine Hazard Areas
We reviewed the referenced coal mine hazard mapping collection to classify existing coal mine
hazard areas on the site in general accordance with chapter 4-3-050 of the Renton Municipal
Code. Based on our document review, it appears that a mine opening located southwest of the
subject property was likely used as an access-way which trended south toward seam workings.
The mine entrance is located southwest of Parcel Number 172305-9069, and is not present on
the property. Based on the reviewed information, the site should be considered a “Declassified”
coal mine hazard because no records of coal mine activity are present on or within 500 feet of
the identified mine opening. The risk of subsidence or related damage associated with coal mine
hazards does not exist on this site.
DISCUSSION AND RECOMMENDATIONS
General
Based on the results of our updated study, construction of the proposed apartment building is
feasible from a geotechnical standpoint. The primary geotechnical considerations associated
with the proposed development include foundation support, minimizing post-construction
settlements, structural fill placement, and the suitability of the on-site soils for use as structural
fill.
GMD Development, LLC ES-5946.03
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Earth Solutions NW, LLC
The proposed apartment building should be supported by a pile foundation system advanced
through the loose soils to bear on firm native soils, or on conventional shallow foundations after
completion of a ground improvement program (rammed aggregate piers, etc.).
The presence of groundwater in excavations that extend below about six to nine feet should be
anticipated. The groundwater table will likely fluctuate throughout the year, depending on many
factors and may rise above the depth where it was observed during the fieldwork. Appropriate
de-watering measures should be incorporated into site designs prior to construction.
ESNW should review final site layout and plans to confirm the geotechnical recommendations in
this report have been incorporated into the plans and to provide supplemental recommendations,
as appropriate.
This study has been prepared for the exclusive use of the GMD Development, LLC and their
representatives. No warranty, expressed or implied, is made. This study has been prepared in
a manner consistent with the level of care and skill ordinarily exercised by other members of the
profession currently practicing under similar conditions in this area.
Site Preparation and Earthwork
With respect to earthwork, the primary considerations at this site are related to structural fill
compaction, moisture sensitivity of the site soils, and foundation support. From a geotechnical
standpoint, the soils encountered at the test sites may not be suitable for use as structural fill
depending on the moisture content at the time of grading. Successful use of the on-site soils will
largely be dictated by the moisture content of the soils at the time of placement and compaction.
The soils encountered at the test sites above the groundwater table were generally in a moist to
wet condition at the time of the exploration (March and April 2018). Soils encountered during site
excavations that are excessively over the optimum moisture content may require moisture
conditioning prior to placement and compaction.
Successful placement and compaction of the on-site soils during periods of extended
precipitation will likely be difficult. If the on-site soils cannot be successfully compacted, the use
of an imported soil may be necessary. Imported soil intended for use as structural fill should
consist of a well graded granular soil with a moisture content that is at or near 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 defined as the percent passing
the #200 sieve, based on the minus three-quarter inch fraction.
Structural fill is defined as compacted soil placed in foundation, slab-on-grade, and roadway
areas. Fills placed to construct permanent slopes and throughout retaining wall and utility trench
backfill areas are also considered structural fill. Soils placed in structural areas should be
compacted to a relative compaction of 95 percent, based on the maximum dry density as
determined by the Modified Proctor Method (ASTM D-1557) and placed in maximum 12 inch lifts.
Temporary construction entrances and drive lanes, consisting of at least 12 inches of quarry
spalls can be considered in order to minimize off-site soil tracking and to provide a relatively firm
temporary road surface. Erosion control measures should consist of silt fencing and surface
water runoff controls.
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Earth Solutions NW, LLC
Foundations
The soils underlying this site are relatively weak and contain compressible layers. Groundwater
was observed at a depth of about six to nine feet below existing grade. Foundations must be
designed to reduce the effects of liquefaction-induced settlement and provide adequate static
support for the new building.
Based on the results of our study and our understanding of the project, the proposed apartment
building should be supported by a pile foundation system advanced through the loose soils to
bear on firm native soils, or on conventional shallow foundations after completion of a ground
improvement program (rammed aggregate piers, etc.). Differential settlement between pile and
non-pile supported elements will occur.
Ground Improvement
Rammed aggregate piers (RAPs) stone columns or other vibro-installation intermediate elements
can be considered as ground-improvement for foundation support. Vibro-installed elements
provide ground improvement between elements, essentially providing ground improvement over
a uniform area. This method provides increased resistance to liquefaction-induced settlement
and would immediately improve the surrounding soil where installed. For preliminary design
considerations, we recommend ground improvement elements be installed to a minimum depth
of 40 feet. ESNW should review proposed designs to confirm the soil parameters used are
representative of the site conditions. For preliminary considerations, foundations supported by
ground improvement elements can be designed 4,000 pounds per square foot (psf) of allowable
bearing capacity.
Pile Foundations
If piles will be pursued for foundation support, we provide capacities for 18 inch diameter
augercast piles. Other pile diameters can also be considered, and should be assessed by ESNW.
The following allowable capacities for 18 inch diameter augercast piles should be used for
foundation design.
Allowable Capacities
* Allowable uplift capacity does not include weight of the pile or pier.
The above allowable capacity is based on a pile length of 40 feet to bear within the medium dense
to dense soil deposits. A higher pile capacity is possible, however, an additional boring would be
necessary to confirm soil conditions at depth. A representative of ESNW should observe the
installation of the foundations and assess pile foundation lengths based on the soil conditions
encountered during the installation.
Lateral Capacities
Diameter
(in.) Compression (kps) Uplift (kps)* 0.5 Inch (kips)
Deflection
1.0 Inch (kips)
Deflection
18 100 55 10 16
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Earth Solutions NW, LLC
Building Slabs
Building slabs should be structurally supported by the pile foundation system if piles are used. If
the ground improvement option is used for foundation support, building slabs can be supported
on grade provided ground improvement program includes slab areas. A capillary break
consisting of a minimum of four inches of free draining crushed rock or gravel should be placed
below the slab. The free draining material should have a fines content of five percent or less
(percent passing the #200 sieve, based on the minus three-quarters inch fraction). In areas
where slab moisture is undesirable, installation of a vapor barrier below the slab should be
considered.
Retaining Walls
If retaining walls will be used for this project, they should be designed to resist earth pressures
and applicable surcharge loads. For design, the following parameters can be assumed for
retaining wall design:
Active earth pressure (yielding condition) 35 pcf (equivalent fluid)
At-rest earth pressure (restrained condition) 55 pcf
Traffic surcharge (passenger vehicles) 70 psf (rectangular distributio n)*
Passive earth pressure 300 pcf (equivalent fluid)
Coefficient of friction 0.40
Seismic surcharge 8H psf**
* Where applicable
** Where H equals the retained height (in feet)
Additional surcharge loading from foundations, sloped backfill, or other loading 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 one foot of the wall
backfill can consist of a less permeable soil, if desired. A perforated drain pipe should be placed
along the base of the wall, and connected to an appropriate discharge location.
GMD Development, LLC ES-5946.03
June 10, 2020 Page 8
Earth Solutions NW, LLC
Seismic Considerations
The 2015 IBC recognizes ASCE for seismic site class definitions. If the project will be permitted
under the 2015 IBC, in accordance with Table 20.3-1 of ASCE, Minimum Design Loads for
Buildings and Other Structures, Site Class E, should be used for design.
In our opinion, liquefaction susceptibility at this site is high due to the soil gradation and
groundwater conditions. Foundations must be designed to resist or reduce the effects of
liquefaction-induced settlement, which can be mitigated using either ground improvement or
piles, as discussed earlier in this report.
Drainage
The seasonal groundwater table was observed at an average depth of approximately six to nine
feet below existing grades during our fieldwork (March and April 2018). As such, the presence
of groundwater should be expected in deeper site excavations, such as those required for utility
improvements or detention vault areas. Temporary measures to control groundwater seepage
and surface water runoff during construction will likely involve interceptor trenches and sumps,
as necessary. Where heavy seepage conditions are encountered, particularly in deeper
excavations, conventional dewatering methods such as pumping wells or well points may be
necessary.
Perimeter drains should be installed below the invert of foundations or pile caps and grade
beams. A typical perimeter drain detail is provided on Plate 3.
Utility Trench Backfill
In our opinion, the soils observed at the test sites are not suitable for direct support of utilities in
the current condition and will require stabilization prior to installing utilities. Moderate to heavy
caving of the site soils should be expected during deeper site excavations. Means of shoring or
sloping excavation walls should be accounted for prior to construction. Organic or highly
compressible soils encountered in the trench excavations should not be used for supporting
utilities. Subgrade stabilization will likely be required and may consist of quarry spalls placed
over a woven geotextile such as Mirafi 500X or approved alternative. In general, the on-site soils
observed at the test sites are not suitable for use as structural backfill in the utility trench
excavations due to the predominately fine-grained texture. Moisture conditioning of the soils may
be necessary at some locations prior to use as structural fill. Utility trench backfill should be
placed and compacted to the specifications of structural fill provided in this report, or to the
applicable specifications of the city or county jurisdictions, as appropriate.
GMD Development, LLC ES-5946.03
June 10, 2020 Page 9
Earth Solutions NW, LLC
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 proofrolling with a loaded dump truck. Structural fill in pavement
areas should be compacted to the specifications detailed in the Site Preparation and Earthwork
section of this report. It is possible that soft, wet, or otherwise unsuitable subgrade areas may
still exist after base grading activities. Areas containing unsuitable or yielding subgrade
conditions may require remedial measures such as overexcavation and 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 relatively lightly loaded pavements subjected to automobiles and occasional truck traffic, the
following sections can be considered:
Two inches of asphalt concrete (AC) placed over four inches of crushed rock base (CRB),
or;
Two inches of AC 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 can be considered:
Three inches of asphalt concrete (AC) placed over six inches of crushed rock base (CRB),
or;
Three inches of AC placed over four and one-half inches of asphalt treated base (ATB).
The AC, ATB and CRB materials should conform to WSDOT specifications.
ESNW can provide appropriate pavement section design recommendations for truck traffic areas
and right-of-way improvements, as necessary. Additionally, the City of Renton Pavement Design
Standards may supersede the recommendations provided in this report.
LIMITATIONS
The recommendations and conclusions provided in this 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. A warranty is not
expressed or implied. Variations in the soil and groundwater conditions observed at the test pit
and boring locations may exist, and may not become evident until construction. ESNW should
reevaluate the conclusions 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 provide testing and
consultation services during construction.
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drwn. CAM
Checked AZS Date June 2020
Date 06/09/2020 Proj. No. 5946.03
Plate 1
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
Vicinity Map
Renton Apartments
Renton, Washington
Reference:
King County, Washington
OpenStreetMap.org
NORTH
NOTE: This plate may contain areas of color. ESNW cannot be
responsible for any subsequent misinterpretation of the information
resulting from black & white reproductions of this plate.
Renton
SITE
Plate
Proj. No.
Date
Checked By
Drwn. ByEarth Solutions NWLLCGeotechnical Engineering,ConstructionObservation/Testing and Environmental ServicesEarthSolutionsNWLLCEarthSolutionsNWLLCss..ggrr aadd yyww aayywwiilllliiaammssaavveennuueess..TP-1
TP-2
B-1
B-101
B-102
B-103
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 Boring, Proj. No.
ES-5946.03, May 2020
Approximate Location of
ESNW Boring, Proj. No.
ES-5946, April 2018
Approximate Location of
ESNW Test Pit, Proj. No.
ES-5946, March 2018
Subject Site
Proposed Building
Existing Building
TP-1
NOT - TO - SCALE
NORTH Subsurface Exploration PlanRenton ApartmentsRenton, Washington
B-101
B-1
CAM
AZS
06/09/2020
5946.03
2
Drwn. CAM
Checked AZS Date June 2020
Date 06/09/2020 Proj. No. 5946.03
Plate 3
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Retaining Wall Drainage Detail
Renton Apartments
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. CAM
Checked AZS Date June 2020
Date 06/09/2020 Proj. No. 5946.03
Plate 4
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Footing Drain Detail
Renton Apartments
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 DRAWING
Earth Solutions NW, LLC
Appendix A
Subsurface Exploration
Boring and Test Pit Logs
ES-5946.03
The subsurface conditions at the site were explored by excavation two test pits and drilling four
boring. The approximate exploration locations are illustrated on Plate 2 of this report. The logs
are provided in this Appendix. The subsurface exploration was completed in March and April
2018 and May 2020. The boring was excavated to a maximum depth of 46.5 feet below existing
grades.
Logs of the borings excavated by ESNW are presented in Appendix A. 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
SS
SS
SS
SS
SS
33
33
50
50
67
2-2-2
(4)
1-2-2
(4)
1-1-1
(2)
1-6-1
(7)
2-2-2
(4)
MC = 26.40%
MC = 30.30%
MC = 58.40%
MC = 41.20%
Fines = 68.20%
MC = 30.10%
SM
ML
SM
Brown silty SAND, very loose, moist
Gray sandy SILT, very loose, moist to wet
[USDA Classification: LOAM]
Gray silty SAND, very loose, wet
-groundwater table
6.0
13.0
NOTES Surface Conditions: field grass
GROUND ELEVATION
LOGGED BY AZS
DRILLING METHOD HSA
HOLE SIZE
DRILLING CONTRACTOR Boretec1, Inc.GROUND WATER LEVELS:
CHECKED BY KRC
DATE STARTED 5/22/20 COMPLETED 5/22/20
AT END OF DRILLING ---
AFTER DRILLING ---
AT TIME OF 14.5 ft
(Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
20
PAGE 1 OF 3
BORING NUMBER B-101
PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments
GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
SS
SS
100
100
100
100
100
1-2-2
(4)
2-3-2
(5)
5-3-8
(11)
7-11-11
(22)
8-15-11
(26)
MC = 35.10%
MC = 108.90%
MC = 24.60%
MC = 11.90%
MC = 9.50%
MC = 15.80%
Fines = 4.10%
SM
SP
Gray silty SAND, very loose, wet (continued)
-1"-2" sand lens
-6" organic lens (peat)
Gray poorly graded SAND, loose, wet
-trace organics
-becomes poorly graded sand with gravel
-becomes medium dense
[USDA Classification: gravelly coarse SAND]
25.0
42.9
(Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)20
25
30
35
40
PAGE 2 OF 3
BORING NUMBER B-101
PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments
GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS 100 9-8-10
(18)MC = 23.90%
SP
Gray poorly graded SAND with gravel, medium dense, wet (continued)
Boring terminated at 46.5 feet below existing grade. Groundwater table
encountered at 14.5 feet during drilling. 2" PVC standpipe installed to bottom of
boring. Lower 20.0 feet slotted. Well ID: BJZ554. Boring backfilled with
bentonite/sand.
46.5SAMPLE TYPENUMBERDEPTH(ft)45
PAGE 3 OF 3
BORING NUMBER B-101
PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments
GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
SS
SS
33
50
33
50
67
2-2-1
(3)
1-1-0
(1)
1-1-1
(2)
1-0-1
(1)
1-1-0
(1)
MC = 13.30%
MC = 43.60%
MC = 82.30%
MC = 37.30%
MC = 92.90%
SM
ML
Brown silty SAND, very loose, moist
Gray SILT, very loose, wet
-wood debris
-wood debris
-groundwater table
4.5
NOTES Surface Conditions: grass
GROUND ELEVATION
LOGGED BY AZS
DRILLING METHOD HSA
HOLE SIZE
DRILLING CONTRACTOR Boretec1, Inc.GROUND WATER LEVELS:
CHECKED BY KRC
DATE STARTED 5/22/20 COMPLETED 5/22/20
AT END OF DRILLING ---
AFTER DRILLING ---
AT TIME OF 13.0 ft
(Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
20
PAGE 1 OF 3
BORING NUMBER B-102
PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments
GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
SS
SS
100
100
100
100
100
2-2-4
(6)
2-4-9
(13)
4-6-5
(11)
2-4-4
(8)
3-4-6
(10)
MC = 30.00%
MC = 16.90%
Fines = 4.10%
MC = 26.90%
MC = 18.30%
MC = 20.70%
ML
SP-
SM
SP
Gray SILT, very loose, wet (continued)
Gray poorly graded SAND with silt, loose, wet/saturated
[USDA Classification: very gravelly coarse SAND]
Gray poorly graded SAND with gravel, medium dense, wet/saturated
-becomes loose
-becomes medium dense
20.5
25.5
(Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)20
25
30
35
40
PAGE 2 OF 3
BORING NUMBER B-102
PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments
GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS 100 5-5-7
(12)MC = 16.20%
SP
Gray poorly graded SAND with gravel, medium dense, wet/saturated
(continued)
Boring terminated at 46.5 feet below existing grade. Groundwater table
encountered at 13.0 feet during drilling. 2" PVC standpipe installed to bottom of
boring. Lower 20.0 feet slotted. Well ID: BJZ555. Boring backfilled with
bentonite/sand.
46.5SAMPLE TYPENUMBERDEPTH(ft)45
PAGE 3 OF 3
BORING NUMBER B-102
PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments
GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
SS
SS
33
67
50
100
2-1-0
(1)
1-1-0
(1)
1-1-1
(2)
2-5-7
(12)
2-2-2
(4)
MC = 38.70%
MC = 38.00%
MC = 77.20%
MC = 40.40%
Fines = 64.40%
MC = 27.50%
ML
SP
Brown sandy SILT, very loose, moist to wet
-wood debris
-becomes gray
-wood debris
[USDA Classification: LOAM]
Gray poorly graded SAND, very loose, wet
-groundwater table
13.0
NOTES Surface Conditions: grass
GROUND ELEVATION
LOGGED BY AZS
DRILLING METHOD HSA
HOLE SIZE
DRILLING CONTRACTOR Boretec1, Inc.GROUND WATER LEVELS:
CHECKED BY KRC
DATE STARTED 5/22/20 COMPLETED 5/22/20
AT END OF DRILLING ---
AFTER DRILLING ---
AT TIME OF 13.5 ft
(Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
20
PAGE 1 OF 3
BORING NUMBER B-103
PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments
GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
SS
SS
100
100
100
100
100
2-2-1
(3)
4-5-9
(14)
4-4-3
(7)
2-3-3
(6)
4-6-6
(12)
MC = 14.50%
MC = 23.50%
MC = 19.00%
MC = 34.20%
MC = 24.00%
SP
ML
SM
Gray poorly graded SAND, very loose, wet (continued)
-4" silt lens
-becomes loose
Gray SILT, loose, wet
Gray silty SAND, medium dense, wet
35.0
38.0
(Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)20
25
30
35
40
PAGE 2 OF 3
BORING NUMBER B-103
PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments
GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS 9-15-10
(25)MC = 21.90%
SM
Gray silty SAND, medium dense, wet (continued)
Boring terminated at 46.5 feet below existing grade. Groundwater table
encountered at 13.5 feet during drilling. Boring backfilled with bentonite.
46.5SAMPLE TYPENUMBERDEPTH(ft)45
PAGE 3 OF 3
BORING NUMBER B-103
PROJECT NUMBER ES-5946.03 PROJECT NAME Renton Apartments
GENERAL BH / TP / WELL - 5946-3.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
SS
SS
SS
22
94
78
100
67
6-4-3
(7)
1-1-1
(2)
3-3-3
(6)
1-1-1
(2)
2-3-4
(7)
MC = 38.10%
MC = 31.60%
MC = 28.90%
MC = 28.70%
MC = 30.50%
SM
TPSL
SM
SM
SP-
SM
ML
1.0
1.5
3.5
8.0
15.5
Brown silty SAND, loose, damp (Fill)
TOPSOIL (Fill)
Brown silty SAND, loose, damp (Fill)
Brown silty SAND, very loose, wet
Gray poorly graded SAND with silt, loose, wet
-groundwater seepage at 9'
-becomes very loose
Gray SILT with sand, loose, wet
NOTES
GROUND ELEVATION
LOGGED BY SES
DRILLING METHOD HSA
HOLE SIZE
DRILLING CONTRACTOR Holocene Drilling GROUND WATER LEVELS:
CHECKED BY SSR
DATE STARTED 4/5/18 COMPLETED 4/5/18
AT TIME OF DRILLING ---
AT END OF DRILLING ---
AFTER DRILLING ---
(Continued Next Page)SAMPLE TYPENUMBERDEPTH(ft)0
5
10
15
20
PAGE 1 OF 2
BORING NUMBER B-1
PROJECT NUMBER ES-5946 PROJECT NAME Renton Mixed-Use
GENERAL BH / TP / WELL - 5946.GPJ - GINT STD US.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
SS
SS
100
100
3-5-9
(14)
7-10-16
(26)
MC = 64.10%
Fines = 98.80%
MC = 196.00%
MC = 38.10%
Fines = 56.60%
ML
PT
ML
21.0
21.5
26.5
Gray SILT with sand, loose, wet (continued)
[USDA Classification: LOAM]
PEAT, wood debris
Gray SILT with sand, medium dense, wet
[USDA Classification: LOAM]
Boring terminated at 26.5 feet below existing grade. Groundwater seepage
encountered at 9.0 feet during drilling. Boring backfilled with bentonite.SAMPLE TYPENUMBERDEPTH(ft)20
25
PAGE 2 OF 2
BORING NUMBER B-1
PROJECT NUMBER ES-5946 PROJECT NAME Renton Mixed-Use
GENERAL BH / TP / WELL - 5946.GPJ - GINT STD US.GDT - 6/10/20Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
RECOVERY %BLOWCOUNTS(N VALUE)TESTS
U.S.C.S.MATERIAL DESCRIPTION
GRAPHICLOG
MC = 15.00%
MC = 26.60%
Fines = 12.80%
MC = 35.80%
Fines = 52.50%
MC = 63.70%
SM
SP-
SM
ML
Dark brown silty SAND, medium dense, damp (Fill)
-large debris
Brown poorly graded SAND with silt, dense, moist
Gray SILT with sand, dense, wet
-caving from 5.5' to BOH
[USDA Classification: LOAM]
-groundwater table at 7'
Test pit terminated at 9.0 feet below existing grade. Groundwater table encountered at 7.0 feet
during excavation. Caving observed from 5.5 feet to BOH.
3.5
5.5
9.0
NOTES Surface Conditions: grass
GROUND ELEVATION
LOGGED BY SES
EXCAVATION METHOD
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY SSR
DATE STARTED 3/20/18 COMPLETED 3/20/18
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
AT TIME OF 7.0 ft
SAMPLE TYPENUMBERDEPTH(ft)0
5
PAGE 1 OF 1
TEST PIT NUMBER TP-1
PROJECT NUMBER ES-5946 PROJECT NAME Renton Mixed-Use
GENERAL BH / TP / WELL - 5946.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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
MC = 23.30%
Fines = 58.40%
MC = 25.50%
MC = 42.70%
Fines = 46.50%
MC = 27.50%
SM
ML
SM
Brown silty SAND, medium dense, damp (Fill)
Brown SILT with sand, medium dense, moist
Black silty SAND, dense, wet
-groundwater table at 6'
-bedded with ML
Test pit terminated at 7.0 feet below existing grade. Groundwater table encountered at 6.0 feet
during excavation. No caving observed.
2.0
5.0
7.0
NOTES
GROUND ELEVATION
LOGGED BY SES
EXCAVATION METHOD
TEST PIT SIZE
EXCAVATION CONTRACTOR NW Excavating GROUND WATER LEVELS:
CHECKED BY SSR
DATE STARTED 3/20/18 COMPLETED 3/20/18
AT END OF EXCAVATION ---
AFTER EXCAVATION ---
AT TIME OF 6.0 ft
SAMPLE TYPENUMBERDEPTH(ft)0
5
PAGE 1 OF 1
TEST PIT NUMBER TP-2
PROJECT NUMBER ES-5946 PROJECT NAME Renton Mixed-Use
GENERAL BH / TP / WELL - 5946.GPJ - GRAPHICS TEMPLATE.GDT - 6/10/20Earth 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-5946.03
Earth Solutions NW, LLC
Report Distribution
ES-5946.03
EMAIL COPY GMD Development, LLC
520 Pike Street, Suite 1010
Seattle, Washington 98101
Attention: Mr. Thomas Geffner