23-101488_Geotech_Letter_3-22-2315365 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
June 3, 2022
ES-8485
American Pride Lending, LLC
P.O. Box 1226
Kent, Washington 98035
Attention: Mr. Sikander Sekhon
Subject: Geotechnical Evaluation
Proposed Short Plat
2240 South 288th Street
Federal Way, Washington
Reference: H.H. Waldron
Geologic Map of the Poverty Bay Quadrangle, 1961
United States Department of Agriculture (USDA)
Natural Resources Conservation Service
Online Web Soil Survey (WSS) Resource
Federal Way Revised Code (FWRC) Chapter 19.145 – Environmentally Critical
Areas
King County Flood Control District
Liquefaction Susceptibility (Map 11-5), dated May 2010
King County Department of Natural Resources and Parks
2021 Surface Water Design Manual, dated July 23, 2021
Dear Mr. Sekhon:
As requested, Earth Solutions NW, LLC (ESNW) has prepared this geotechnical evaluation for
the subject site. We performed our work in general accordance with the scope of services
outlined in our proposal dated March 10, 2022, which was authorized by you on March 29, 2022.
A summary of the field investigation and pertinent geotechnical design recommendations and
conclusions are provided in this letter.
American Pride Lending, LLC ES-8485
June 3, 2022 Page 2
Earth Solutions NW, LLC
Project & Site Description
The subject site is located directly northwest of the intersection between South 288th Street and
23rd Place South in Federal Way, Washington. The approximate site location is illustrated on the
attached Vicinity Map (Plate 1). The site is comprised of one tax parcel (King County Parcel No.
332204-9023), totaling about 0.9 acres.
The subject site is currently unoccupied. Based on review of historical aerial photographs
available on the King County iMap, the site was previously developed with a single-family
residence which appears to have been removed sometime between 2002 and 2005; subsequent
to removal of the structure, the site appears to have been cleared and somewhat regraded
sometime between 2007 and 2009. Site topography gently descends to the southwest. Total
elevation change across the subject site is approximately 15 feet. Vegetation consists of field
grass and a few mature trees.
Based on conceptual plans communicated to us, we four new single-family homes will be
constructed on the subject site. Grading plans were not available at the time of this evaluation;
however, based on the existing site topography, we anticipate grading will consist of cuts and fills
of less than about 5 to 10 feet.
Subsurface
An ESNW representative observed, logged, and sampled three test pits on April 14, 2022. The
test pits were excavated within accessible areas of the site using a mini trackhoe and operator
retained by ESNW. The test pits were completed to assess soil conditions, classify site soils,
and characterize groundwater conditions within the proposed development area. The
approximate locations of the test pits are depicted on the attached Plate 2 (Test Pit Location
Plan). Please refer to the attached test pit logs for a more detailed description of subsurface
conditions. Representative soil samples collected at the test pit locations were analyzed in
general accordance with both Unified Soil Classification System (USCS) and USDA methods and
procedures.
Topsoil
Topsoil, was generally encountered within the upper 6 to 12 inches below the existing ground
surface (bgs). The topsoil was characterized by its dark brown color, the presence of fine organic
material, and root intrusions extending up to three feet bgs.
Fill
Fill was encountered at all test pit locations during our subsurface exploration extending to a
depth of approximately two feet bgs. The fill is characterized as silty sand with gravel in a loose
and moist condition. Based on the existing site conditions and review of historical aerial
photographs, we anticipate that fill will be encountered across the majority of the buildable site
area.
American Pride Lending, LLC ES-8485
June 3, 2022 Page 3
Earth Solutions NW, LLC
Native Soil
Underlying topsoil and fill, native soil was encountered as medium dense to very dense silty
gravel with varying amounts of sand (USCS: GW-GM and GM). Native soil relative density
generally increased with depth and becomes weakly cemented beginning at depths of roughly
three to four feet bgs. Native soil was generally encountered in a moist to wet condition.
Geologic Setting
The referenced geologic map identifies ground moraine deposits (Qgt) across the subject
property and surrounding area. As reported on the geologic map resource, ground moraine
deposits are comprised of compact, unoxidized glacial till. The material is typically very dense
and weakly cemented resulting from glacial overburden. Glacial till is commonly termed
“hardpan” in western Washington. Distinct features of the material are compactness, ability to
maintain near-vertical slopes, very low permeability, and a heterogenous internal structure
resembling a low-strength concrete. Based on our field observations, native soil likely to be
exposed during grading activities will be consistent with glacial till deposits.
The referenced WSS resource identifies arents of Alderwood material (Map Unit: AmC) as the
primary soil unit underlying the subject site. Soils of the arents of Alderwood series are
associated with glacial till ridge and hill landforms, which were modified by human grading activity.
The native soil observed is generally consistent with Alderwood series soil.
Groundwater
Groundwater was encountered at test pit locations TP-1 and TP-2 during the April 2022
subsurface exploration. The light groundwater seepage was observed at depths of about four
and five bgs. Additionally, light iron oxide staining was observed at all test pit locations at a depth
of about three feet bgs, which is indicative of seasonal groundwater seepage. Groundwater
seepage rates and elevations fluctuate depending on many factors, including precipitation
duration and intensity, the time of year, and soil conditions. In general, groundwater flow rates
are higher during the winter, spring, and early summer months.
Critical Areas Review
ESNW reviewed FWRC Chapter 19.145 to determine if geologically relevant critical areas
recognized by Federal Way (including erosion, landslide, and seismic hazard areas) exist on or
near the subject site. Our review indicates that these critical areas have not been mapped on
site or in proximity to the site. Based on our field observations, it is our opinion the site is correctly
mapped outside of the geologically relevant critical areas listed herein.
Discussion & Recommendations
The following sections provide discussion and recommendations to aid with the design and
construction of the proposed single-family residences and related improvements.
American Pride Lending, LLC ES-8485
June 3, 2022 Page 4
Earth Solutions NW, LLC
In-Situ and Imported Soil
Most of the in-situ soils encountered at the subject site have a moderate to high sensitivity to
moisture and were generally in a moist to wet condition at the time of exploration. Soils
anticipated to be exposed on site will degrade if exposed to wet weather and construction traffic.
Compaction of the soils to the levels necessary for use as structural fill may be difficult or
impossible during wet weather conditions. Soils encountered during site excavations that are
excessively over the optimum moisture content will likely require aeration or treatment prior to
placement and compaction. Conversely, soils that are substantially below the optimum moisture
content will require moisture conditioning through the addition of water prior to use as structural
fill. An ESNW representative should determine the suitability of in-situ soils for use as structural
fill at the time of construction.
Imported soil intended for use as structural fill should consist of a well-graded, granular soil with
a moisture content that is at (or slightly above) the optimum level. During wet weather conditions,
imported soil intended for use as structural fill should consist of a well-graded, granular soil with
a fines content of 5 percent or less (where the fines content is defined as the percent passing the
Number 200 sieve, based on the minus three-quarter-inch fraction).
Structural Fill
Structural fill is defined as compacted soil in foundation, slab-on-grade, driveway, retaining wall,
and utility trench areas. Soils placed in structural areas should be placed in maximum 12-inch
loose lifts 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). Fill should
be placed on a firm and level surface. ESNW should be consulted during early grading activities
to provide additional recommendations regarding structural fill placement, where necessary.
Excavations and Slopes
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, are recommended. The
applicable Federal Occupation Safety and Health Administration (OSHA) and Washington
Industrial Safety and Health Act (WISHA) soil classifications are also provided:
Loose soil 1.5H:1V (Type C)
Areas exposing groundwater seepage 1.5H:1V (Type C)
Medium dense soil 1H:1V (Type B)
Dense to very dense “hardpan” native soil 0.75H:1V (Type A)
American Pride Lending, LLC ES-8485
June 3, 2022 Page 5
Earth Solutions NW, LLC
ESNW can evaluate the feasibility of utilizing steeper temporary slopes at the time of construction.
In any case, an ESNW representative should observe temporary slopes to confirm inclinations
are suitable for the exposed soil conditions and to provide additional excavation and slope
stability recommendations, as necessary. If the recommended temporary slope inclinations
cannot be achieved, temporary shoring may be necessary to support excavations. Permanent
slopes should be graded to 2H:1V (or flatter) and planted with vegetation to enhance stability and
minimize erosion potential. Permanent slopes should be observed by ESNW prior to vegetation
and landscaping.
Foundations
In our opinion, the proposed single-family residential structures can be constructed on a
conventional continuous and spread footing foundation bearing on competent native soil,
recompacted native soil, or new structural fill placed directly on competent native soil. Competent
native soil suitable for support of foundations will likely be encountered beginning at depths of
about two to three feet bgs. Where loose or unsuitable soil conditions are exposed at foundation
subgrade elevations, compaction of the soil to the specifications of structural fill or overexcavation
and replacement with suitable structural fill will be necessary.
Provided the foundations will be supported as described above, the following parameters may be
used for design:
Allowable soil bearing capacity 2,500 psf
Passive earth pressure 300 pcf
Coefficient of friction 0.40
The passive earth pressure value provided above assumes the foundations will be backfilled with
structural fill. A factor-of-safety of 1.5 has been applied to the passive earth pressure and
coefficient of friction values provided in this section. For short-term wind and seismic loading, a
one-third increase in the allowable soil bearing capacity may be assumed. With structural loading
as expected, total settlement of about one inch and differential settlement of approximately one-
half inch is anticipated. Most of the anticipated settlement should occur during construction, as
dead loads are applied.
Slab-on-Grade Floors
Slab-on-grade floors should be supported on a suitable capillary break material underlain by a
compacted and competent subgrade. Structural fill in slab-on-grade areas should be compacted
to a minimum relative compaction of 95 percent. Unstable or yielding areas of the subgrade
should be recompacted, or overexcavated and replaced with suitable structural fill, prior to slab
construction.
American Pride Lending, LLC ES-8485
June 3, 2022 Page 6
Earth Solutions NW, LLC
Slab-on-grade areas should be provided with a minimum four-inch-thick capillary break. Capillary
break soils should consist of a granular, free-draining coarse sand and gravel soil that contains
less than 5 percent fines (percent passing the Number 200 sieve, based on the minus three-
quarter-inch fraction). To facilitate grading of the slab subgrade, the maximum aggregate size of
the capillary break material should generally be one-and-one-quarter inch. In areas where slab
moisture is undesirable, installation of a vapor barrier placed below the slab should be
considered. If a vapor barrier will be utilized, it should consist of a material specifically designed
for that use and should be installed in accordance with the specifications of the manufacturer.
Seismic Design
The 2018 International Building Code (2018 IBC) recognizes the most recent edition of the
Minimum Design Loads for Buildings and Other Structures manual (ASCE 7-16) for seismic
design, specifically with respect to earthquake loads. Based on the soil conditions encountered
at the test pit locations, the parameters and values provided below are recommended for seismic
design per the 2018 IBC.
Parameter Value
Site Class C*
Mapped short period spectral response acceleration, SS (g) 1.336
Mapped 1-second period spectral response acceleration, S1 (g) 0.458
Short period site coefficient, Fa 1.200
Long period site coefficient, Fv 1.500
Adjusted short period spectral response acceleration, SMS (g) 1.603
Adjusted 1-second period spectral response acceleration, SM1 (g) 0.687
Design short period spectral response acceleration, SDS (g) 1.069
Design 1-second period spectral response acceleration, SD1 (g) 0.458
*Assumes very dense soil conditions, encountered to a maximum depth of 10 feet bgs during the March 2022 field
exploration, remain very dense to at least 100 feet bgs. Based on our experience with the project geologic setting
(glacial till) across the Puget Sound region, soil conditions are likely consistent with this assumption.
Liquefaction is a phenomenon where saturated and loose cohesionless soil suddenly loses
internal strength and behaves as a fluid. This behavior is in response to increased pore water
pressures resulting from an earthquake or another intense ground shaking. In our opinion, site
susceptibility to liquefaction can be considered negligible. The composition and relatively dense
characteristics of the native soil were the primary bases for this opinion.
American Pride Lending, LLC ES-8485
June 3, 2022 Page 7
Earth Solutions NW, LLC
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 (unrestrained condition) 35 pcf (equivalent fluid)
At-rest earth pressure (restrained condition) 55 pcf
Traffic surcharge* (passenger vehicles)70 psf (rectangular distribution)
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).
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; a typical retaining wall drainage
detail (Plate 3) is attached to this letter. The upper 12 inches of the wall backfill may consist of a
less permeable soil, if desired. A sheet drain may be considered in lieu of free-draining backfill.
A perforated drainpipe should be placed along the base of the wall and connected to an approved
discharge location. If drainage is not provided, hydrostatic pressures should be included in the
wall design.
Drainage
Groundwater was encountered at test pit locations TP-1 and TP-2 at depths of about four feet
and five feet, respectively. Based on the encountered soil types, we anticipate groundwater
seepage to be common during subsurface excavations on the subject property, particularly during
utility excavations. Temporary measures to control groundwater seepage and surface water
runoff during construction will likely involve passive elements such as interceptor trenches and
sumps, as necessary.
Surface grades must be designed to direct water away from structures and slopes. The grade
adjacent to the buildings should be sloped away from the buildings at a gradient of at least 2
percent for a minimum horizontal distance of either 10 feet or as setbacks allow. In our opinion,
perimeter footing drains should be installed at or below the invert of the building footings. A
typical footing drain detail is provided on Plate 4 of this report. If footing drains are not installed,
we recommend backfilling footings with a relatively impermeable soil.
American Pride Lending, LLC ES-8485
June 3, 2022 Page 8
Earth Solutions NW, LLC
Preliminary Infiltration Evaluation
We understand on-site stormwater infiltration is being considered for the proposed project. Based
on existing grades, we would anticipate project grading to include cuts of about 5 to 10 feet, which
would expose weakly cemented, low permeability soil. Based on our subsurface observations of
glacial till deposits and indications of seasonal groundwater seepage (iron oxide staining) as
shallow as about three feet bgs, we do not recommend incorporating infiltration into the overall
stormwater design. However, ESNW can further evaluate the potential for limited infiltration
BMPs based on proposed site design, if requested.
Limitations
This letter has been prepared for the exclusive use of American Pride Lending, LLC and their
representatives. No warranty, express or implied, is made. The recommendations and
conclusions provided in this letter 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. If the design assumptions outlined in this letter either change or are incorrect, or if
construction conditions differ from those encountered during our fieldwork, ESNW should be
contacted to review the recommendations and conclusions provided in this letter.
Additional Services
ESNW should have an opportunity to review the final design with respect to the geotechnical
recommendations provided in this letter. ESNW should also be retained to provide testing and
consultation services during construction.
American Pride Lending, LLC ES-8485
June 3, 2022 Page 9
Earth Solutions NW, LLC
We trust this letter meets your current needs. Should you have any questions regarding the
content herein, or require additional information, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
Samuel E. Suruda, L.G. Henry T. Wright, P.E.
Senior Staff Geologist Associate Principal Engineer
Attachments: Plate 1 – Vicinity Map
Plate 2 – Test Pit Location Plan
Plate 3 – Retaining Wall Drainage Detail
Plate 4 – Footing Drain Detail
Test Pit Logs
Grain Size Distribution
cc: Encompass Engineering & Surveying
Attention: Ms. Heather Tatro (Email only)
06/03/2022
Drwn.CAM
Checked SES Date May 2022
Date 05/31/2022 Proj.No.8485
Plate 1
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
Vicinity Map
S.288th Street Short Plat
Federal Way,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.
Federal Way
SITE
Drwn.CAM
Checked SES Date May 2022
Date 05/31/2022 Proj.No.8485
Plate 2
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
TP-1TP-2
TP-3
s.288th street
Test Pit Location Plan
S.288th Street Short Plat
Federal Way,Washington
NOTE:This plate may contain areas of color.ESNW cannot be
responsible for any subsequent misinterpretation of the information
resulting from black &white reproductions of this plate.
NOTE:The graphics shown on this plate are not intended for design
purposes or precise scale measurements,but only to illustrate the
approximate test locations relative to the approximate locations of
existing and /or proposed site features.The information illustrated
is largely based on data provided by the client at the time of our
study.ESNW cannot be responsible for subsequent design changes
or interpretation of the data by others.
LEGEND
Approximate Location of
ESNW Test Pit,Proj.No.
ES-8485,April 2022
Subject Site
Existing Building
TP-1
NOT -TO -SCALE
NORTH
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drwn.CAM
Checked SES Date May 2022
Date 05/31/2022 Proj.No.8485
Plate 3
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
NOTES:
Free-draining Backfill should consist
of soil having less than 5 percent fines.
Percent passing No.4 sieve should be
25 to 75 percent.
Sheet Drain may be feasible in lieu
of Free-draining Backfill,per ESNW
recommendations.
Drain Pipe should consist of perforated,
rigid PVC Pipe surrounded with 1-inch
Drain Rock.
LEGEND:
Free-draining Structural Backfill
1-inch Drain Rock
18"Min.
Structural
Fill
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
SCHEMATIC ONLY -NOT TO SCALE
NOT A CONSTRUCTION DRAW ING
Retaining Wall Drainage Detail
S.288th Street Short Plat
Federal Way,Washington
Geotechnical Engineering,Construction
Observation/Testing and Environmental Services
Drwn.CAM
Checked SES Date May 2022
Date 05/31/2022 Proj.No.8485
Plate 4
Earth Solutions NWLLCEarthSolutionsNWLLC
EarthSolutions
NW LLC
Slope
Perforated Rigid Drain Pipe
(Surround in Drain Rock)
18"Min.
NOTES:
Do NOT tie roof downspouts
to Footing Drain.
Surface Seal to consist of
12"of less permeable,suitable
soil.Slope away from building.
LEGEND:
Surface Seal:native soil or
other low-permeability material.
1-inch Drain Rock
SCHEMATIC ONLY -NOT TO SCALE
NOT A CONSTRUCTION DRAW ING
Footing Drain Detail
S.288th Street Short Plat
Federal Way,Washington
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
MC = 20.2%
MC = 9.4%
Fines = 11.7%
MC = 6.2%
MC = 6.0%
TPSL
SM
GW-
GM
Dark brown TOPSOIL, trace roots to 3' (Fill)
Brown silty SAND with gravel, loose to medium dense, moist (Fill)
Brown well-graded GRAVEL with silt and sand, medium dense, wet
-becomes gray, dense, moist, weakly cemented
[USDA Classification: extremely gravelly coarse sandy LOAM]
-light iron oxide staining
-light groundwater seepage
-becomes dense to very dense
Test pit terminated at 9.5 feet below existing grade. Groundwater seepage encountered at 4.0
feet during excavation. No caving observed.
1.0
2.0
9.5SAMPLE TYPENUMBERDEPTH(ft)0.0
2.5
5.0
7.5
PAGE 1 OF 1
TEST PIT NUMBER TP-1
NOTES Depth of Topsoil & Sod 8-12": brambles
LOGGED BY KTK
EXCAVATION METHOD
EXCAVATION CONTRACTOR NW Excavating
CHECKED BY HTW
DATE STARTED 4/14/22 COMPLETED 4/14/22
GROUND WATER LEVEL:
AT TIME OF EXCAVATION
GROUND ELEVATION
LATITUDE 47.34381 LONGITUDE -122.30325
PROJECT NUMBER ES-8485 PROJECT NAME S. 288th Street Short Plat
GENERAL BH / TP / WELL - 8485.GPJ - GRAPHICS TEMPLATE WITH LAT AND LONG.GDT - 5/31/22Earth 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 = 13.0%
MC = 19.7%
MC = 9.3%
MC = 8.5%
Fines = 35.5%
TPSL
SM
GM
Dark brown TOPSOIL (Fill)
Brown silty SAND with gravel, loose, moist (Fill)
Brown silty GRAVEL with sand, medium dense, wet
-becomes moist
-becomes gray, dense, weakly cemented, light iron oxide staining
-becomes dense to very dense
-light groundwater seepage
[USDA Classification: gravelly LOAM]
Test pit terminated at 10.0 feet below existing grade. Groundwater seepage encountered at 5.0
feet during excavation. No caving observed.
1.0
2.0
10.0SAMPLE TYPENUMBERDEPTH(ft)0.0
2.5
5.0
7.5
10.0
PAGE 1 OF 1
TEST PIT NUMBER TP-2
NOTES Depth of Topsoil & Sod 8-12": grass
LOGGED BY KTK
EXCAVATION METHOD
EXCAVATION CONTRACTOR NW Excavating
CHECKED BY HTW
DATE STARTED 4/14/22 COMPLETED 4/14/22
GROUND WATER LEVEL:
AT TIME OF EXCAVATION
GROUND ELEVATION
LATITUDE 47.34381 LONGITUDE -122.30368
PROJECT NUMBER ES-8485 PROJECT NAME S. 288th Street Short Plat
GENERAL BH / TP / WELL - 8485.GPJ - GRAPHICS TEMPLATE WITH LAT AND LONG.GDT - 5/31/22Earth 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 = 12.1%
MC = 10.8%
Fines = 22.9%
MC = 9.2%
MC = 8.2%
TPSL
SM
GM
Dark brown TOPSOIL (Fill)
Brown silty SAND with gravel, loose, moist (Fill)
Brown silty GRAVEL with sand, medium dense, moist
-light iron oxide staining
[USDA Classification: very gravelly sandy LOAM]
-becomes gray, dense, weakly cemented
-becomes dense to very dense
Test pit terminated at 10.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
0.5
2.0
10.0SAMPLE TYPENUMBERDEPTH(ft)0.0
2.5
5.0
7.5
10.0
PAGE 1 OF 1
TEST PIT NUMBER TP-3
NOTES Depth of Topsoil & Sod 6": grass
LOGGED BY KTK
EXCAVATION METHOD
EXCAVATION CONTRACTOR NW Excavating
CHECKED BY HTW
DATE STARTED 4/14/22 COMPLETED 4/14/22
GROUND WATER LEVEL:
AT TIME OF EXCAVATION
GROUND ELEVATION
LATITUDE 47.34368 LONGITUDE -122.30407
PROJECT NUMBER ES-8485 PROJECT NAME S. 288th Street Short Plat
GENERAL BH / TP / WELL - 8485.GPJ - GRAPHICS TEMPLATE WITH LAT AND LONG.GDT - 5/31/22Earth 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
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
3
D100
140
Specimen Identification
1
fine
6
HYDROMETER
304
11.7
35.5
22.9
101/2
COBBLES
Specimen Identification
4
coarse
20 401.5 8 14
USDA: Brown Extremely Gravelly Coarse Sandy Loam. USCS: GW-GM with Sand.
USDA: Gray Gravelly Loam. USCS: SM with Gravel.
USDA: Brown Very Gravelly Sandy Loam. USCS: GM with Sand.
6 60
PERCENT FINER BY WEIGHTD10
1.032
0.171
17.862
0.551
3.915
GRAIN SIZE DISTRIBUTION
100
335.22
LL
TP-01
TP-02
TP-03
3/4
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS
GRAVEL SAND
75
37.5
37.5
%Silt
1.12
TP-01
TP-02
TP-03
2 2003
Cc CuClassification
%Clay
16
PID60 D30
coarse SILT OR CLAYfinemedium
GRAIN SIZE IN MILLIMETERS
3/8 50
3.0ft.
10.0ft.
3.5ft.
3.00ft.
10.00ft.
3.50ft.
PL
PROJECT NUMBER ES-8485 PROJECT NAME S. 288th Street Short Plat
GRAIN SIZE USDA ES-8485 S. 288TH STREET SHORT PLAT.GPJ GINT US LAB.GDT 5/12/22Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711