REVIEWED ENG BLD2023-0292+Geotechnical_Report+3.7.2023_3.34.40_PM+3407213.,.,.,.,.,.REVIEWED ,.,.,.,.•.•
BY
CITY OF EDMONDS
BUILDING DEPARTMENT
May 19, 2021
Updated January 4, 2022
ES-7515
RECEIVED
3/13/23
CITY OF EDMONDS
DEVELOPMENT
SERVICES DEPARTMENT
Select Homes, Inc.
8304 — 212t" Street Southwest
Edmonds, Washington 98026
Attention: Ms. Kayla Nichols
Subject: Geotechnical Evaluation
Proposed Single -Family Residences
8929 — 220t" Street Southwest
Edmonds, Washington
Earth
Solutions
NW«c
Earth Solutions NW LLC
Geotechnical Engineering, Construction
Observation/Testing and Environmental Services
Reference: Department of Ecology
Stormwater Management Manual for Western Washington
Amended December 2014
James P. Minard
Geologic Map of the Edmonds East and Part of the Edmonds West Quadrangles
Washington, 1983
United States Department of Agriculture (USDA)
Web Soil Survey (WSS)
Edmonds City Code
Chapter 23.80 (Geologically Hazard Areas)
RAM Engineering, Inc.
Preliminary Engineering Plans, revised October 13, 2021
Dear Ms. Nichols:
As requested, Earth Solutions NW, LLC (ESNW) has prepared this geotechnical evaluation report
for the proposed single-family residences. As part of our scope of services, we completed a
subsurface exploration, laboratory and engineering analyses, in -situ infiltration testing, and
prepared this written report with our findings and recommendations for the proposed project.
Based on our evaluation, the proposed project is feasible from a geotechnical standpoint. This
geotechnical evaluation has been updated to respond to City of Edmonds review comments.
15365 N.E. 90th Street, Suite 100 0 Redmond, WA 98052 6 (425) 449-4704 • FAX (425) 449-4711
Select Homes, Inc.
May 19, 2021
Updated January 4, 2022
Response to Comments
ES-7515
Page 2
The comments pertinent to the geotechnical aspects of the project are provided below, followed
by our responses. ESNW prepared the referenced geotechnical evaluation for the subject
project.
Review Comment SW32-1 — Expand or clarify the findings of this test as noted:
a) Text states test was at contact of till layer, but no layer distinction is shown in the boring
log at that elevation; explain/update as needed.
b) Expand on what was observed/noted to lead to the conclusion water travelled horizontally.
c) Expand engineering opinion of reason for this observation; it appears unusual to the
reviewer given the relatively uniform boring logs and without explanation from engineer.
d) Explain why perforated pipe connections are considered feasible given finding of
infiltration testing; if separation to hardpan layer is infeasibility criteria for all infiltration
BMPs, it would also appear to apply to perforated pipe connections.
ESNW Response — The following is provided as additional clarification as requested:
a) The infiltration test was completed at a depth of approximately four feet at TP-2, which is
the same depth noted on test pit log TP-2 where the material changes from brown and
loose to medium dense, to gray and medium dense to dense. This transition was
interpreted as the transition from weathered glacial till to unweathered glacial till.
b) This conclusion was based on the observation that the water from the infiltration test was
perched on the unweathered till and began to seep back into the test pit from that transition
level as the test pit was advanced deeper after completion of the infiltration test.
c) The test pit logs do not illustrate uniform soil conditions from top of the test pits to the
bottom of the test pits; changes in color, density, and cementation illustrate the change
from weathered till to unweathered till. The water from the infiltration test did not
significantly infiltrate vertically into the unweathered till and was observed to seep back
into the test pit as it was advanced deeper after completion of the test. Glacial till is a
widely documented and prevalent geologic deposit in the Puget Sound region, which
consists of weathered till within the upper few feet underlain by unweathered till. The
weathered till generally exhibits low to moderate hydraulic conductivity and the
unweathered till generally exhibits very low to negligible hydraulic conductivity. This is due
to the increased density and cemented nature of the unweathered till.
d) Based on proposed grades, the bottom of the perforated stub -out connection trenches
would be within the underlying unweathered till. In this respect, perforated stub -out
connections should be considered infeasible for the proposed project. We have updated
the BMP table in this report accordingly.
Earth Solutions NW. LLC
Select Homes, Inc.
May 19, 2021
Updated January 4, 2022
Protect Description
ES-7515
Page 3
The subject site is located at 8929 — 220th Street Southwest in Edmonds, Washington, as
illustrated on the attached Vicinity Map (Plate 1). The site consists of one tax parcel (Snohomish
County parcel number 0038030010-1000) totaling approximately 0.61 acres of land. The
property is currently developed with a single-family residence, outbuildings, and associated
improvements. Site topography is relatively level with less than about five feet of elevation
change. The subject site is bordered to the north, east, and west by single-family residences and
to the south by 220th Street Southwest.
Based on ESNW's understanding of the proposed development, the subject site will be
redeveloped with three single-family residences and associated improvements. We anticipate
grading activities will include cuts and fills of about two to four feet to establish the planned
building alignments. However, grading plans were not available at the time this report was
prepared. We understand infiltration and low impact development methods are being evaluated
for stormwater management. Site improvements will also include underground utility
installations.
At the time this report was prepared, specific building load values were not available. However,
we anticipate the proposed residential structures will consist of relatively lightly loaded wood
framing supported on conventional foundations. Based on our experience with similar
developments, we estimate wall loads on the order of one to two kips per linear foot and slab -on -
grade loading of 150 pounds per square foot (psf).
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 the
geotechnical recommendations provided in this report have been incorporated into the plans.
Subsurface Conditions
As part of this geotechnical evaluation, an ESNW representative observed, logged, and sampled
five test pits on October 16, 2020, excavated at accessible locations within the proposed
development area, using a mini-trackhoe and operator provided by the client. The approximate
locations of the test pits are depicted on the Test Pit Location Plan (Plate 2). Please refer to the
test pit logs provided as an attachment to this report for a more detailed description of subsurface
conditions. Representative soil samples collected at the test pit locations were analyzed in
general accordance with the Unified Soil Classification System (USCS) and USDA methods and
procedures.
Topsoil and Fill
Native topsoil was observed extending to depths of approximately two to nine inches below the
existing ground surface (bgs). The topsoil was characterized by dark brown color and fine organic
material.
Earth Solutions NW. LLC
Select Homes, Inc.
May 19, 2021
Updated January 4, 2022
ES-7515
Page 4
Fill was observed at test pit location TP-2. The fill was observed to extend to a maximum depth
of roughly 12 inches bgs. The fill was characterized primarily as topsoil and loose silty sand
(USCS: SM), and was encountered in a moist condition at the time of exploration. Additionally,
fill may be present within proximity to existing structural improvements. Where fill is encountered
during construction, ESNW should be consulted to evaluate the suitability for support of the
proposed structures and/or reuse as structural fill.
Native Soil
Underlying the topsoil and limited fill, native soil at the test pit locations was observed to consist
primarily of silty sand with and without gravel (USCS: SM). Silt gravel (USCS: GM) was observed
within the upper three feet at test pit location TP-5. Overall soil relative density generally
increased with depth, extending to the maximum exploration depth of about seven and one-half
feet bgs. The native soil was generally observed in a weakly cemented condition beginning at
about three and one-half to four feet bgs.
Geologic Setting
The referenced geologic map resource identifies Vashon till (Qvt) across the site and surrounding
areas. As reported on the geologic map resource, Vashon till typically consists of a nonsorted
mixture of clay, silt, sand, pebbles, cobbles, and boulders. The till was deposited directly by ice
advanced over previously deposited sediment and rocks. In addition, the referenced WSS
resource identifies Alderwood-urban land complex (Map Unit Symbol: 5) as the primary soil units
underlying the subject site. The Alderwood series was formed in glacial till plains. Based on our
field observations, native soils on the subject site are generally consistent with the geologic
setting outlined in this section.
Groundwater
Groundwater seepage was not observed at the test pit locations during the fieldwork (October
2020). However, seepage should be expected in deeper excavations at this site, particularly
during the winter, spring, and early summer months. Groundwater seepage rates and elevations
fluctuate depending on many factors, including precipitation duration and intensity, the time of
year, and soil conditions.
Geologically Hazardous Areas Assessment
As part of this geotechnical evaluation, the referenced chapter of the ECC was reviewed. Based
on our investigation and review, there are no geologically hazardous areas present on or adjacent
to the site.
Earth Solutions NW. LLC
Select Homes, Inc.
May 19, 2021
Updated January 4, 2022
Foundations
ES-7515
Page 5
The proposed structures can be supported on conventional spread and continuous footings
bearing on undisturbed, competent native soil, compacted native soil, or new structural fill.
Competent native soils, suitable for support of the foundation, should be encountered beginning
at depths of approximately two to three feet bgs. Where loose or unsuitable soil conditions are
encountered at foundation subgrade elevations during site preparation activities, compaction of
the soils to the specifications of structural fill, or overexcavation and replacement with granular
structural fill will be necessary. Structural fill should consist of suitable granular soils compacted
to 95 percent of Modified Proctor (ASTM D1557). Compaction of the soil to the levels necessary
for use as structural fill will be difficult during wet weather conditions. Organic material exposed
at foundation subgrade elevations must be removed and grades restored with structural fill.
Provided the structures will be supported as described above, the following parameters can be
used for design of the new foundations:
• Allowable soil bearing capacity 2,500 psf
• Passive earth pressure 300 pcf (equivalent fluid)
• Coefficient of friction 0.40
The passive earth pressure and coefficient of friction values include a safety factor of 1.5. A one-
third increase in the allowable soil bearing capacity can be assumed for short-term wind and
seismic loading conditions.
With structural loading as expected, total settlement in the range of one inch is anticipated, with
differential settlement of about one-half inch. The majority of the settlements should occur during
construction, as dead loads are applied.
Seismic Considerations
The 2015 and 2018 International Building Code recognizes the American Society of Civil
Engineers (ASCE) for seismic site class definitions. In accordance with Table 20.3-1 of ASCE,
Minimum Design Loads for Buildings and Other Structures, Site Class D, should be used for
design.
In our opinion, the site susceptibility to liquefaction is negligible. The native soil relative density
and the absence of an established, shallow groundwater table are the primary bases for this
opinion.
Drainage
Temporary measures to control surface water runoff during construction would likely involve
passive elements such as interceptor trenches and sumps. ESNW should be consulted during
preliminary grading activities to evaluate seepage areas and provide recommendations to reduce
the potential for seepage -related instability.
Earth Solutions NW. LLC
Select Homes, Inc.
May 19, 2021
Updated January 4, 2022
ES-7515
Page 6
Finish grades should be designed to direct surface water away from structures and slopes.
Grades adjacent to buildings should be sloped away at a gradient of either at least 2 percent for
a horizontal distance of up to 10 feet or the maximum allowed by adjacent structures. In our
opinion, foundation drains should be installed along building perimeter footings.
Infiltration and LID Evaluation
As indicated in the Subsurface Conditions section, native soils encountered during our fieldwork
were characterized primarily as silty sand with and without gravel. Based on the results of USDA
textural analyses, the native soils at depth were classified primarily as gravelly loamy sand with
fines contents of about 18 percent.
In -situ testing was completed in accordance with the small-scale pilot infiltration test (PIT)
procedure, as outlined in Volume III, Chapter 3, Page 526 of the 2014 SMMWW. The PIT was
completed at a depth of approximately four feet at TP-2. The testing was completed at the contact
with the unweathered glacial till. The in -situ rate obtained during testing was 23.0 inches per
hour (iph); however, based on conditions observed when advancing the test pit after completion
of the PIT, it was evident that much of the water infiltrated laterally within the upper weathered
soil.
We understand the proposed development area of the site is clustered due to tree retention and
ECDC 20.75.048. Due to the clustered houses and site improvements, we understand there is
limited remaining area for infiltration, bioretention, or dispersion systems and required minimum
setbacks. Based on the confining layer observed during the infiltration test, attempting to infiltrate
stormwater will create lateral flow along the confining layer and is ultimately not recommended
for limited setback conditions.
On -site Stormwater Management
Pursuant to City of Edmonds stormwater management requirements, implementation of on -site
stormwater BMPs are required for proposed developments in accordance with specified
thresholds, standards, and lists. The intent of BMP implementation is to infiltrate, disperse, and
retain stormwater runoff on site to the extent feasible. The table below summarizes our
evaluation of low impact development methods, as outlined in the referenced stormwater manual,
from a geotechnical standpoint. It is instructed in the referenced stormwater manual that BMPs
are to be considered in the order listed (from top to bottom) for each surface type, and the first
BMP that is determined to be viable should be used. For completeness, however, we have
evaluated each listed BMP for the proposed surface types.
Earth Solutions NW. LLC
Select Homes, Inc.
May 19, 2021
Updated January 4, 2022
ES-7515
Page 7
BMP
I Viable?
Limitations or Infeasibility Criteria
Lawns and Landscaped Areas
T5.13: Post -construction soil
quality and depth (Volume V,
Yes
None.
Chapter 5
Roofs
T5.30: Full dispersion (Volume V,
Maybe*
T5.30: Adequate vegetative flow paths will likely not be
Chapter 5)
available.
T5.10A: Downspout full infiltration
T5.10A: Shallow depth to low permeability soil and limited
systems (Volume III, Chapter 3)
No
setback space due to clustered development.
Roofs
Bioretention (Volume V, Chapter
NO
T5.10A: Shallow depth to low permeability soil and limited
7)
setback space due to clustered development.
T5.1013: Downspout dispersion
Maybe*
Adequate vegetative flow paths are likely not available.
systems (Volume III, Chapter 3)
T5.10C: Perforated stub -out
Based on proposed grades, the bottom of the perforated
connections (Volume III, Chapter
No
stub -out connection trenches would be within the
3)
underlying unweathered till.
T5.30: Full dispersion (Volume V,
Maybe*
Adequate vegetative flow paths are likely not available.
Chapter 5)
T5.15: Permeable pavement
Shallow depth to lower permeability soil would cause
(Volume V, Chapter 5)
No
saturation and instability of soil directly supporting the
pavement.
Bioretention (Volume V, Chapter
NO
T5.10A: Shallow depth to low permeability soil and limited
7)
setback space due to clustered development.
T5.12: Sheet flow dispersion
No flooding or erosion impacts are anticipated. However,
T5.11: Concentrated flow
Maybe*
adequate vegetative flow paths are likely not available.
dispersion Volume V, Chapter 5
* Viability stated from a geotechnical standpoint and should be determined by site storm designer with respect to
setbacks and flow paths.
Limitations
The recommendations and conclusions provided in this geotechnical evaluation report 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
locations may exist and may not become evident until construction. ESNW should reevaluate
the conclusions in this geotechnical evaluation report if variations are encountered.
Earth Solutions NW. LLC
Select Homes, Inc.
May 19, 2021
Updated January 4, 2022
Additional Services
ES-7515
Page 8
ESNW should be retained to provide additional geotechnical services in association with this
project, including testing and consulting services during construction. ESNW should have an
opportunity to review final project plans with respect to geotechnical recommendations provided
in this letter.
We trust this letter meets your current needs. Should you have questions, or if any additional
information is required, please call.
Sincerely,
EARTH SOLUTIONS NW, LLC
Adam Z. Shier, L.G.
Project Geologist
Attachments: Plate 1 — Vicinity Map
Plate 2 — Test Pit Location Plan
Test Pit Logs
Grain Size Distribution
�T'WR
�F WA 6.
Q
"� 53803
Fss/ONAL
01 /04/2022
Henry T. Wright, P.E.
Senior Project Manager
cc: RAM Engineering, Inc.
Attention: Mr. Rob Long, P.E. (Email only)
Earth Solutions NW. LLC
C ry
h r
203rtl Street Southwest
D ♦a < Glen Street < ZGlen Street Glen Street
'h,
Daley Street zDaley Sheet G Daley Street °
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//SSr Pei Sprague Street °' Sprague Street _
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\ Bell Street
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ayton Street Dayton Street
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Street N
a
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v
m
i
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Spruce streeta' Woodway
'D 80"/do/ l High School
da n Wdy oa
Hem.lock Way
p' J Laurel Street 215th Street Southwest
s Edmonds
wPm Street Chose Lake r"
m Pine Street 216th Street Southwest 216th Street Southwest A . c 216th Street Southwest _
l s 9 Elementary
11
D School
IFOrsyth Laneg zt 7th Street Southwest 1 ;
3
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01 Fir Street. 3 v ` A 218th Street Southwest
°
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o
Elm street — =220Ih.Street Southwest_ _—220th-Street.Southwest__
04 Elm
D222nd Street Southwest
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as Park
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\\d --- —
\ v Esperance —
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\ D d 228th_St[eeLSou[hwest of
7S
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oad .. 14 3
^ \ 231st Street Southwest
� 9othQa°°
232nd Street Southwest
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�F WA99
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% Edmonds 30 Maple Lane O,q
_
° 00 Heights N 234th Street Southwest gal a� 234th Street South
Nottingham Road K72~1 ill Madrona Lane
235Ih Place Southwest a
F 236th Street Southwest 236th Street Southwest
\ _
Reference: NORTH
County, Washington
arth 1 1Snohomish
i
[ENWIULC
OpenStreetMap.org
.Geotechnical Engineering, Construction
Vicinity Map
8929 - 220th Street Southwest
Edmonds, Washington
NOTE: This plate may contain areas of color. ESNW cannot be
responsible for any subsequent misinterpretation of the information
Drwn. MRS
Date 11 /18/2020
Proj. No. 7515
resulting from black & white reproductions of this plate.
Checked AZS
Date Nov. 2020
Plate 1
I I
¢zo I
- - - - 425_ 1_ _� II
r—T-1/�
------I— — — — ——
I �—■t I I
,I415
42�
I TP-3 1
TP-2
I
I I
II TP-41
I E]
I
n
t i
I I TP-5 1 —
I I
11 \ I
415
`420
22OTH STREET S.W.
LEGEND NORTH
TP-1 Approximate Location of 00�
— ■ — ESNW Test Pit, Proj. No.
ES-7515, Oct. 2020
Subject Site
Existing Building NOT - TO - SCALE
NOTE: The graphics shown on this plate are not intended for design ' ' '
purposes or precise scale measurements, but only to illustrate the 0.
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 Test Pit Location Plan
study. ESNW cannot be responsible for subsequent design changes 8929 - 220th Street Southwest
or interpretation of the data by others. Edmonds, Washington
NOTE: This plate may contain areas of color. ESNW cannot be Drwn. MRS Date 11 /18/2020 Proj. No. 7515
responsible for any subsequent misinterpretation of the information
resulting from black & white reproductions of this plate. Checked AZS Date Nov. 2020 Plate 2
Earth Solutions NWLLC
SOIL CLASSIFICATION CHART
MAJOR DIVISIONS
SYMBOLS
TYPICAL
DESCRIPTIONS
GRAPH
I LETTER
GRAVEL
AND
CLEAN
GRAVELS
• �••
.�
GW
WELL -GRADED GRAVELS, GRAVEL -
SAND MIXTURES, LITTLE OR NO
FINES
° �a o �a
o p�o p
Q oQ
GAP
POORLY -GRADED GRAVELS,
GRAVEL - SAND MIXTURES, LITTLE
OR NO FINES
GRAVELLY
SOILS
(LITTLE OR NO FINES)
COARSE
GRAINED
SOILS
MORE THAN 50%
OF COARSE
GRAVELS WITH
FINES
°
�0
00
D
O
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
SP
POORLY -GRADED SANDS,
GRAVELLY SAND, LITTLE OR NO
FINES
LARGER THAN
N0. 200 SIEVE
SIZE
SANDY
SOILS
(LITTLE OR NO FINES)
SANDS WITH
FINES
c
SM
SILTY SANDS, SAND - SILT
MIXTURES
MORE THAN 50%
OF COARSE
FRACTION
PASSING ON NO.
4 SIEVE
(APPRECIABLE
AMOUNT OF FINES)
CC
S
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
CL
INORGANIC CLAYS OF LOW TO
MEDIUM PLASTICITY, GRAVELLY
CLAYS, SANDY CLAYS, SILTY CLAYS,
LEAN CLAYS
FINE
GRAINED
SOILS
SILTS
AND LIQUID LIMIT
LESS THAN 50
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 LIQUID LIMIT
AND GREATER THAN 50
CLAYS
CH
INORGANIC CLAYS OF HIGH
PLASTICITY
OH
ORGANIC CLAYS OF MEDIUM TO
HIGH PLASTICITY, ORGANIC SILTS
HIGHLY ORGANIC SOILS
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.
Earth Solutions NW, LLC TEST PIT NUMBER TP-1
YPRII 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-7515 PROJECT NAME 8929 - 220th Street Southwest
DATE STARTED 10/16/20 COMPLETED 10/16/20 GROUND ELEVATION
EXCAVATION CONTRACTOR Client Provided LATITUDE LONGITUDE
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY AZS CHECKED BY HTW SL AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 6": ivy/forest duff
w
_
CL
~W
_
wJ
CO
TESTS
Q O
MATERIAL DESCRIPTION
p
d7
W
Q Z
(�
0
TPSL '. : 0.5
Dark brown TOPSOIL, roots
Tan silty SAND, loose to medium dense, moist
MC = 6.3%
SM
. 3.0
Gray silty SAND, medium dense, moist
MC = 5.9%
weakly cemented
5 MC = 2.2%
SM
MC = 4.0% 7.5
Test pit terminated at 7.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
r Earth Solutions NW, LLC
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
TEST PIT NUMBER TP-2
PAGE 1 OF 1
PROJECT NUMBER ES-7515 PROJECT NAME 8929 - 220th Street Southwest
DATE STARTED 10/16/20 COMPLETED 10/16/20 GROUND ELEVATION
EXCAVATION CONTRACTOR Client Provided LATITUDE LONGITUDE
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY AZS CHECKED BY HTW S7 AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 2": grass
w
CL
_
w
~W
J g
TESTS
_
Q O
u/i
Q z
0
SM
MC = 10.5%
SM
MC = 4.9%
Fines = 18.1 %
5
SM
MC = 13.6%
Finpc = 1R F0/
MATERIAL DESCRIPTION
0.3� Dark brown TOPSOIL (Fill)
1.0 Tan silty SAND, loose, moist (Fill)
1.5 Dark brown TOPSOIL
Brown silty SAND, loose to medium dense, moist
Gray silty SAND, medium dense to dense, moist
[USDA Classification: slightly gravelly loamy SAND]
-infiltration test at 4', groundwater seepage from test
-increasing gravel
[USDA Classification: gravelly loamy SAND]
Test pit terminated at 7.5 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
Earth Solutions NW, LLC TEST PIT NUMBER TP-3
YPRII 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-7515 PROJECT NAME 8929 - 220th Street Southwest
DATE STARTED 10/16/20 COMPLETED 10/16/20 GROUND ELEVATION
EXCAVATION CONTRACTOR Client Provided LATITUDE LONGITUDE
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY AZS CHECKED BY HTW SL AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 2": ivy
w
_
CL
~W
_
wJ
g
TESTS
Q O
MATERIAL DESCRIPTION
p
CL
Q Z
(�
0
TPSL —n
Dark brown TOPSOIL, roots
Brown silty SAND, loose to medium dense, moist
MC = 6.4%
SM
2.5
Gray silty SAND, medium dense to dense, moist
MC = 3.0%
SM
-weakly cemented
5
MC = 5.1 % 6.0
Test pit terminated at 6.0 feet below existing grade due to refusal on till. No groundwater
encountered during excavation. No caving observed.
Earth Solutions NW, LLC TEST PIT NUMBER TP-4
YPRII 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-7515 PROJECT NAME 8929 - 220th Street Southwest
DATE STARTED 10/16/20 COMPLETED 10/16/20 GROUND ELEVATION
EXCAVATION CONTRACTOR Client Provided LATITUDE LONGITUDE
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY AZS CHECKED BY HTW SL AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 6": grass/exposed soil
w
_
CL
~W
_
wJ
g
TESTS
Q O
MATERIAL DESCRIPTION
p
CL
Q Z
(�
0
TPSL '. : 0.5
Dark brown TOPSOIL
Brown silty SAND, loose to medium dense, moist
MC = 9.0%
SM
2.0
Gray silty SAND, medium dense to dense, moist
MC = 2.1 %
-weakly cemented
SM
5
MC = 8.1 % 7.0
Test pit terminated at 7.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
Earth Solutions NW, LLC TEST PIT NUMBER TP-5
YPRII 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-7515 PROJECT NAME 8929 - 220th Street Southwest
DATE STARTED 10/16/20 COMPLETED 10/16/20 GROUND ELEVATION
EXCAVATION CONTRACTOR Client Provided LATITUDE LONGITUDE
EXCAVATION METHOD GROUND WATER LEVEL:
LOGGED BY AZS CHECKED BY HTW SL AT TIME OF EXCAVATION
NOTES Depth of Topsoil & Sod 9": grass
w
_
CL
~W
_
wJ
g
TESTS
Q O
MATERIAL DESCRIPTION
p
CL
Q Z
(�
0
TPSL
Dark brown TOPSOIL, roots
a.� 0.7
°
°
Brown silty GRAVEL with sand, loose to medium dense, moist
MC=7.1% °
Fines = 20.0% GM 0
° °
[USDA Classification: very gravelly sandy LOAM]
3.0
Gray silty SAND, medium dense to dense, moist
MC = 2.4%
-weakly cemented
5 SM
MC = 10.6% 7.0
Test pit terminated at 7.0 feet below existing grade. No groundwater encountered during
excavation. No caving observed.
Earth Solutions NW, LLC GRAIN SIZE DISTRIBUTION
15365 N.E. 90th Street, Suite 100
Redmond, Washington 98052
Telephone: 425-449-4704
Fax: 425-449-4711
PROJECT NUMBER ES-7515 PROJECT NAME 8929 - 220th Street Southwest
U.S. SIEVE OPENING IN INCHES U.S. SIEVE NUMBERS I HYDROMETER
6 4 3 2 1 5 1 1/2W 3 4 6 810 1416 20 30 40 50 60 100140 200
100
95
90
85
80
75
70
65
w 60
55
m
w
50
z
LL
45
z
w
� 40
w
a
35
30
25
20
15
10
5
0
100 10 1 0.1 0.01 0.001
GRAIN SIZE IN MILLIMETERS
COBBLES
GRAVEL
SAND
W
N
U)
z