REVIEWED PLN BLD2023-0084+Geotech Report+1.20.2023_4.43.53_PM+3326299RECEIVED
Jan 312023
CITY OF EDMONDS
DEVELOPMENTSERVICES
DEPNRTMENT
Group Northwest, Inc.
October 5th 2022
Mr. Da Zhang
Email: da@truescapedesign.com
Subject: Geotechnical Engineering Investigation
Proposed Landscaping and Retaining Wall
18303 84th Pl W
Edmonds, Washington
Dear Mr. Zhang:
BLD2023-0084
Geolechnical Engineers, Geologists
& Environmental Specialists
G-5766
------- - - - - - -
Reviewed by
City of Edmonds ;
Planning Division
'---------------
At your request, GEO Group Northwest, Inc., conducted a geotechnical engineering
investigation at the above -subject location for a proposed new retaining wall and landscaping
design. The Edmonds property is primarily flat with a steep slope on the east most property line
dropping downslope to a roadway behind the property. We understand that the proposed
backyard landscaping project will involve a 4-foot-high retaining wall tracing the slope along the
east side of the property and adding a pool, patio, deck and pergola to the current yard. The City
of Edmonds has requested a geotechnical report evaluating the proposal consistent with the
requirements of ECDC 23.80.060 and .070. The scope of our services included a review of the
geologic maps of the area and providing a characterization of the subsurface soil conditions
encountered, preparation of test pit logs (attached) and preparation of this geotechnical report.
SITE CONDITIONS
Site Description
The project site is located in north Edmonds, Washington as illustrated in Plate I — Site Location
Map. The parcel is rectangle -shaped and consists of 0.36 Acres. It is primarily flat with a steep
slope on the east most property line dropping down to a road behind the property. The site is
bounded by other single family residential properties to the north and south, and is backed by
13705 Bel -Red Road • Bellevue, Washington 98005
Phone 425/649-8757 • Fax 425/649-8758
October 51h 2022 G-5766
Da Zhang Page 2
841h Avenue W to the east and 84th Place W to the west, in front of the property. The 1959 house
has a single story with a full basement and both floors have a total of 1687 square feet of living
space. There is also a 545 square foot detached garage on the property to the south side of the
house.
Description of Proposed Development
We understand that the proposed development will be a new 4-foot-high retaining wall spanning
the length of the east property line and a small portion of the north property line. There are
currently some rocks tracing a portion of the top of the slope. The project will also include
adding an above ground pool, patio, deck and pergola to the backyard area of the property. The
proposed concrete block retaining wall will be approximately 5 feet from the top of the slope,
and will be backfilled and the yard leveled. In the center of the yard, an at grade deck and a 20-
foot-long above grade Modpool will be to the east of the existing house. The Modpool is
approximately 12-14 feet away from the edge of the slope at its closest point and is proposed to
be supported on a compacted gravel base and a concrete pad and will be 5-5.5 feet high. To the
east of the existing garage, the proposed landscaping includes a paved patio, walkway and
pergola. Please see Plate 2- Site Plan.
SITE INVESTIGATION
Geologic Overview
Based on a review of the geologic map for the area, the project site overlies Glacial Till (Qvt).
Glacial Till deposits typically consist of very compact mixtures of sand, silt, clay, and gravel that
were overridden and over -consolidated by glacial ice during the Fraser glaciation period which
ended approximately 13,000 years ago. The site has a steep slope on the east side of the property
that is mapped as a city of Edmonds high landslide and erosion hazard area.
Subsurface Investigation
On September 20th 2022, a Staff Engineering Geologist from our firm, visited the site to perform
a visual reconnaissance of the site and investigate the subsurface soil conditions. Due to length of
the proposed wall, two hand augers were dug at different distances from the top of the slope, and
the entire north -south span of the slope was probed to observe the depths to dense soils. Two
hand auger borings were dug, the boring locations are illustrated in Plate 2 — Site Plan.
GEO Group Northwest, Inc.
October 51h 2022 G-5766
Da Zhang Page 3
The soil conditions encountered in the two borings were relatively similar, they typically had
medium dense, dry silty sand with a low fines content underlain by very dense silty sand with a
low fines content. The soil in Hand Auger 1 (HA-1), which was furthest to the west, became
dense at approximately 1.5 feet below ground surface and Hand Auger 2 (HA-2), which was
closest to the top of the slope in the east, became dense at a depth of 2.5 feet. The accessible soils
a few feet away from the proposed retaining wall were probed onsite. Overall, soils
approximately 5-10 feet from the top of the slope probed 6 inches to 1 foot, and soils closer to
the house 10-15 feet from the top of the slope probed approximately 0-6 inches. Hand Auger
logs are attached in Appendix A.
CRITICAL AREAS REVIEW AND EVALUATION
Per the City of Edmonds Critical Area map, the property has areas labeled as low, medium and
high landslide and erosion hazards onsite. The city of Edmonds has requested a geotechnical
report evaluating the proposal consistent with the requirements of ECDC 23.80.060 and .070.
The slope onsite is mapped as a high landslide hazard in the north-east corner and along the east
property line. This high landslide hazard portion of the slope extends over the property line 30-
40 feet. This slope is approximately 40 percent grade with 24 feet of vertical elevation change
from top to bottom. The slope is mapped as a medium landslide and erosion hazard throughout
the center and north-east side of the backyard, and as a low landslide and erosion hazard in the
front yard. From our observations onsite, the area designated as a medium landslide hazard is
primarily flat.
The proposed concrete block retaining walls will follow the contour of the slope rim, keeping the
wall an even 5 feet from the top of the slope along the entire east property line. As observed in
our subsurface exploration above, soil in HA-1, which was furthest to the west, became dense at
approximately 1.5 feet below ground surface and HA-2, which was closest to the top of the slope
in the east, became dense at a depth of 2.5 feet. The footing of the wall will bear down on the
dense native soils and will be backfilled to level the yard.
In our opinion, because of the dense native soils onsite that the retaining wall will bear on, the
slope face not being altered and the 5-foot-buffer atop the slope, the alteration of the critical area
will not increase the threat of the geological hazard to adjacent properties, adversely impact other
critical areas beyond predevelopment conditions. The wall being built on dense native soils 1-3
feet below the ground surface, and respecting a setback from the property line, in our opinion,
GEO Group Northwest, Inc.
October 51h 2022 G-5766
Da Zhang Page 4
designs the project so that the hazard is mitigated to a level equal to or less than predevelopment
conditions.
Based on the results of our subsurface investigation, in our opinion, the slopes on the property
showed no signs of deep instability in the dense native soils.
Buffer Recommendations
The subsurface soils onsite were observed to be dense to very dense at approximately 2.5 feet
below the ground surface 3-4 feet from the top of the slope and 1.5 feet below the ground surface
12 feet away. We recommend a buffer of 5 feet from the edge of the slope be in place for the
retaining wall.
CONCLUSIONS AND RECOMMENDATIONS
The project area within the site is underlain with a medium dense topsoil of weathered till above
stiff, sandy soils interpreted to be dense native Glacial Till. The subsurface soils onsite became
dense to very dense between 2 and 2.5 feet below the ground surface in the approximate location
of the proposed retaining wall. To the west of the wall where the proposed paved patio, modpool,
walkway and pergola are to be located, the depth to dense soils was approximately 1.5- 2 feet
below ground surface.
In our opinion, the retaining wall and the proposed landscaping modifications can be supported
with conventional concrete footing foundations that bear on dense native soils or on structural fill
that is placed on a subgrade of dense native soil. We recommend the proposed 4-foot-high wall
be a concrete block retaining wall, and should be constructed on the dense soils and backfilled
with structural fill. Proper backfill with free draining material should be installed behind the
wall. We recommend a buffer of 5 feet for the retaining wall from the top of the steep slope.
Detailed recommendations regarding geotechnical aspects of the project are presented in the
following sections of this report.
Seismicity Evaluation
In accordance with the 2018 International Building Code, the site classification is Site Class C
(dense soil). Glacially consolidated soils have a high shear strength and the potential for
GEO Group Northwest, Inc.
October 51h 2022 G-5766
Da Zhang Page 5
landslides, liquefaction and/or lateral spreading is negligible during a strong motion earthquake.
In our opinion, the site is stable and the risk of a surface rupture, resulting from a large
magnitude seismic event, is very low. No seismic mitigation measures are recommended. Based
on the assigned Site Class C the design calculations per the 2018 IBC, are as follows:
SS = 1.303g Sms = 1.564 Sd, = 1.043
Si = 0.46lg Smi = 0.692 Sal = 0.461
The peak ground acceleration for the site, adjusted for the assigned site class, is 0.558 g based on
USGS seismic hazard design mapping per the 2018 IBC.
Pool Support
Soils that are anticipated to be acceptable for pool support were encountered at a depth of
approximately 2-2.5 feet bgs in the location of the proposed retaining wall and approximately
1.5-2 feet in the location of the other landscaping additions further from the slope. Based on
these findings, it is our opinion that new foundations for the project can consist of conventional
concrete footings or a structural slab that bear directly on dense or very dense native soils or on
compacted, crushed rock structural fill that has been placed on a subgrade of dense or very dense
native soils. Our recommended design criteria for conventional footing foundations supported
on native soils or crushed rock structural fill are provided below.
- Allowable bearing pressure, including all dead and live loads:
Undisturbed, dense or very dense soil = 2,000 psf
Structural fill placed on dense or very dense soil = 2,000 psf
- Minimum depth to base of perimeter footing below adjacent exterior grade = 18 inches
- Minimum depth to bottom of interior footings below top of floor slab = 12 inches
- Minimum width of wall footings = 16 inches
- Estimated post -construction settlement = 1/2 inch
- Estimated post -construction differential settlement across width = 1/2inch
A one-third increase in the above allowable bearing pressures can be used when considering
short-term transitory wind or seismic loads.
GEO Group Northwest, Inc.
October 5th 2022 G-5766
Da Zhang Page 6
Lateral loads against the building foundations can be resisted by friction between the foundation
and the supporting subgrade or by passive earth pressure acting on the buried portions of the
foundations. For the latter case, the foundations must be poured "neat" against the existing
undisturbed soil or be backfilled with compacted structural fill. Our recommended parameters
are as follows:
- Passive Pressure (Lateral Resistance)
350 pcf, equivalent fluid weight, for structural fill or competent undisturbed
native soil
- Coefficient of Friction (Friction Factor)
0.35 for structural fill or competent undisturbed native soil
Concrete Block Retaining Walls
We recommend that the block walls be supported either on a prepared, compacted subgrade
capable of supporting the wall load or on structural fills underlain by competent native soils. This
recommendation is applicable for low -height; independent walls which are primarily for limited
grade changes or hardscape improvements and have bearing pressures of 2,000 pounds per
square foot or less. The following recommended design parameters are applicable to fully
drained walls.
Passive Earth Pressure and Base Friction
The available passive earth pressure that can be mobilized to resist lateral forces may be assumed
to be equal to 350 pcf equivalent fluid weight for both undisturbed soils and engineered
structural fill. The base friction that can be generated between concrete and undisturbed bearing
soils or engineered structural fill may be based on an assumed 0.35. The soil design parameters
are allowable values and include a safety factor of 2.
The active and at -rest design pressures are based on a fully drained wall condition and do not
include the effects of surcharges. For sloped ground above walls, a surcharge equivalent to
50 percent of the soil height above the wall (soil unit weight 125 pcf) should be used in addition
to the above soil pressure. Traffic and construction equipment surcharge may be considered as a
uniform surcharge equivalent to two (2) feet of soil acting over the full depth of the active
GEO Group Northwest, Inc.
October 51h 2022 G-5766
Da Zhang Page 7
pressure. Restrained walls designed should be backfilled after completing their lateral restraint is
in place or per the approval of the structural design engineer.
Drainage and Backfill
There should be approximately 12-18 inches of free draining crushed rock backfill. The backfill
in areas adjacent to retaining walls should be compacted with hand held equipment (such as a
jumping jack) or with a small hoe -pack.
Drainage
Water should not be allowed to stand in areas where footings, slabs, or pavements are to be
constructed. Final site grades should provide drainage away from structures. The pool should
not be drained into the critical area but should be connected to the storm system.
Footing drains, consisting of a 4-inch minimum diameter, rigid perforated drain pipe, should
extend around new perimeter foundations and be installed behind new retaining walls. Footing
drains should be bedded in washed drain rock and the rock wrapped with geotextile filter fabric,
such as Mirafi 140N, or equivalent. Drain rock should extend above the base of the vertical drain
mat. Roof and other drain lines should not be connected to the footing drain system. We
recommend installing a sump pump system if the footing drain system cannot drain by gravity to
a discharge location. Installation of clean -outs are recommended to allow periodic maintenance
of the drain system.
Grading and Earthwork
Erosion Control
Temporary erosion and sedimentation controls (TESCs), such as silt fences, should be installed
down -gradient of the areas to be disturbed to prevent sediment -laden runoff from being
discharged off site. Surface runoff should not be allowed to flow over the top of slopes into
excavations. During wet weather, exposed soils should be covered with plastic sheeting or straw
mulch. Stockpiled soils should be covered with plastic tarps. For permanent erosion control
disturbed soils should be landscaped and mulched upon completion of the site work.
A construction entrance consisting of 2- to 4-inch size crushed rock should be installed to
prevent tracking onto the street. The construction entrance area should be cleared and grubbed
prior to rock placement and we recommend underlaying the rock with a woven geotextile such as
Mirafi 500X, or equivalent, to provide separation between the rock and subgrade soil.
GEO Group Northwest, Inc.
October 51h 2022 G-5766
Da Zhang Page 8
Excavations and Slopes
Temporary excavation slopes should not be greater than the limits specified in local, state and
federal government safety regulations. We recommend that temporary cuts greater than 4 feet in
height be sloped at inclinations up to 1H:1V (Horizontal: Vertical) in loose to medium dense
soils. Temporary excavations in very dense, hardpan soils can be sloped near vertical under the
observation of the geotechnical engineer. Permanent cut and fill slopes should be inclined no
steeper than 2.5H:IV. Steeper permanent fill slopes can be achieved with the use of geogrid for
lateral reinforcement. Slopes that are to be maintained or mowed should be sloped at 3H:1V, or
less. Fill slopes should consist of granular material compacted to a minimum of 90 percent of the
material's maximum dry density. If supporting structural elements, the fill should be compacted
to the structural fill specification of 92 percent. Based on the subsurface findings, no
groundwater seepage is anticipated. If water seepage or other adverse conditions are
encountered, excavation should be halted, and the geotechnical engineer should be contacted to
review the site conditions.
Subgrade Preparation
Shallow subsurface soils at the project area on the site are anticipated to typically consist of
dense silty sand. If specific areas of especially soft soils, organics, or other deleterious materials
are encountered during this work, they should be over -excavated to an appropriate depth as
recommended by the geotechnical engineer and replaced with gravel or crushed rock.
Structural Fill
Structural fill is defined as fill soil supporting building foundations, floor slabs, pavements,
sidewalks or other fat work. Structural fill should be free of organic and other deleterious
substances and have a maximum fragment size of 3 inches. The site soils contain silt. It can be
difficult to achieve compaction with soils containing silt, especially during wet weather, subject
to the material's moisture content. During wet weather we recommend a free -draining granular
material containing no more than 5 percent fines content (silt and clay -size particles passing the
No. 200 mesh sieve). Other materials, such as recycled crushed concrete or crushed rock may be
used. The site soils should not be used as structural fills for the proposed development.
Structural fill should be placed and compacted at or near the material's optimum moisture
content and in lifts that are 10 inches thick or less. Below slab -on -grade floors, foundations, and
other structural elements, structural fill should be compacted to a minimum of 92 percent of the
GEO Group Northwest, Inc.
October 51h 2022 G-5766
Da Zhang Page 9
material's maximum dry density, as determined by ASTM Test Designation D-1557 (Modified
Proctor). For driveways, structural fill should be compacted to 90 percent, with the exception of
the top 12 inches which should be compacted to 95 percent. Fill behind retaining walls and next
to building foundation walls should be compacted to a minimum of 90 percent (92 percent if
supporting structural elements; if supporting pavements, the top 12 inches should be compacted
to 95 percent).
Utility trench backfill within the City right-of-way should be compacted to the specifications
required by the City, sewer or water district. Observation and compaction testing will be
required at the time of fill placement to document and verify that the compaction specifications
are achieved.
LIMITATIONS
The findings and recommendations stated herein are based on field observations, our experience
on similar projects and our professional judgment. The recommendations presented herein are
our professional opinions derived 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 and within the project schedule and budget constraints. No warranty is
expressed or implied. In the event that site conditions are found to differ from those described in
this report, we should be notified so that the relevant recommendations in this report can be
reevaluated and modified if appropriate.
CLOSING
We appreciate the opportunity to provide you with geotechnical engineering services for this
project. Please do not hesitate to contact us if you have any questions regarding this report.
Sincerely,
GEO Group Northwest, Inc.
GEO Group Northwest, Inc.
October 51h 2022
G-5766
Da Zhang Page 10
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Sophie Holt, G.I.T.
Staff Engineering Geologist
Attachments:
Plate I — Site Location Map
Plate 2 — Site Plan
William Chang, P.E.
Principal Engineer
Plate 3 — Geologic Critical Areas
Plate 4 — Typical Footing Drain
Appendix A — USCS Soil Classification Legend & Soil Boring Logs
GEO Group Northwest, Inc.
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Source: King County iMap, 2021
SITE LOCATION MAP
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GroupNorthwest Inc. � PROPOSED LANDSCAPING
- Geotechnical Engineers, Geologists, & 18303 84TH PL W
Environmental Scientists
EDMONDS, WASHINGTON
SCALE NONE DATE 10/5/2022 1 MADE SH CHKD WC I JOB NO. G-5766 I PLATE 1
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REMOVED \ REMOVED 1
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(E)HOUSE TYP.
�(E) SHRUBS BLOCK
TO REMAIN, RETAINING I
TYP. - WALL I
MAIN CONCRETE
ENTRY STEPS. TYP.
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OPE
(E I PATIO AT -GRADE
PAVED DECK
_ WALKWAY
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(EI GARAGE " 4" PAVED PATIO
WALKWAY
LEGEND
AND AUGER
LOCATION
HAND AUGER LOCATION
Group Northwest, Inc. PROPOSED LANDSCAPING
18303 84TH PL W
- Geotechnical Engineers, Geologists, &
Environmental Scientists EDMONDS, WASHINGTON
SCALE: NO SCALE DRAWN: SH TECKED: WC DATE: 10/5/2022 PROJECT NO.: G-5766 PLATE 2
1'
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ENVIRONMENTAL CRITICAL AREAS
Group Northwest, Inc. PROPOSED LANDSCAPING
18303 84TH PL W
- Geotechnical Engineers, Geologists, &
Environmental Scientists EDMONDS, WASHINGTON
SCALE: NO SCALE DRAWN: SH [CHECKED: WC DATE: 10/5/2022 PROJECT NO.: G-5766 PLATE 3
October 5th 2022
G-5766
Da Zhang Page 11
APPENDIX A
USCS Soil Classification Leizend & Soil Boring Logs
GEO Group Northwest, Inc.
SOIL CLASSIFICATION & PENETRATION TEST DATA EXPLANATION
MAJOR DIVISION
CLEAN
GRAVELS
GRAVELS
(little or no
(More Than Half
fines)
COARSE-
Coarse Fraction is
GRAINED SOILS
Larger Than No. 4
Sieve)
DIRTY
GRAVELS
(with some
fines)
SANDS
CLEAN
SANDS
(More Than Half
More Than Half
Coarse Fraction is
(little or no
by Weight Larger
Smaller Than No.
fines)
Than No. 200
4 Sieve)
Sieve
DIRTY
SANDS
(with some
fines)
SILTS
Liquid Limit
(Below A -Line on
< 50%
Plasticity Chart,
Liquid Limit
FINE-GRAINED
Negligible
SOILS
Organics)
> 50%
CLAYS
Liquid Limit
(Above A -Line on
< 50%
Plasticity Chart,
Liquid Limit
Negligible
Organics)
> 50%
Less Than Half by
Weight Larger
Liquid Limit
Than No. 200
ORGANIC SILTS
<50°/
Sieve (i.e., fines)
& CLAYS
(Below A -Line on
Plasticity Chart)
Liquid Limit
> 50%
HIGHLY ORGANIC SOILS
UNIFIED
SOIL CLASSIFICATION SYSTEM (USCS)
GROUP
TYPICAL DESCRIPTION
LABORATORY CLASSIFICATION CRITERIA
SYMBOL
WELL GRADED GRAVELS, GRAVEL -SAND
Cu = (1360 / D10) greater than 4
GW
MIXTURE, LITTLE OR NO FINES
CONTENT
Cc = (D30)2 / (D10 " D60) between 1 and 3
OF FINES BELOW
POORLY GRADED GRAVELS, AND GRAVEL -SAND
5 %
CLEAN GRAVELS NOT MEETING ABOVE
GP
MIXTURES LITTLE OR NO FINES
REQUIREMENTS
GM
SILTY GRAVELS, GRAVEL -SAND -SILT MIXTURES
GM: ATTERBERG LIMITS BELOW "A" LINE.
CONTENT
or P.I. LESS THAN 4
OF FINES EXCEEDS
CLAYEY GRAVELS, GRAVEL -SAND -CLAY
12%
GC: ATTERBERG LIMITS ABOVE "A" LINE.
GC
MIXTURES
or P.I. MORE THAN 7
WELL GRADED SANDS, GRAVELLY SANDS,
Cu = (1360 / D10) greater than 6
SW
LITTLE OR NO FINES
CONTENT
Cc = (D30)2 / (D10 " D60) between 1 and 3
OF FINES BELOW
POORLY GRADED SANDS, GRAVELLY SANDS,
5%
CLEAN SANDS NOT MEETING ABOVE
SP
LITTLE OR NO FINES
REQUIREMENTS
SM
SILTY SANDS, SAND -SILT MIXTURES
ATTERBERG LIMITS BELOW "A" LINE
with P.I. LESS THAN 4
CONTENT OF FINES
EXCEEDSI2%
ATTERBERG LIMITS ABOVE "A" LINE
SC
CLAYEY SANDS, SAND -CLAY MIXTURES
with P.I. MORE THAN 7
ML
MH
CL
CH
OL
OH
Pt
SOIL PARTICLE SIZE
U.S. STANDARD SIEVE
FRACTION
Passing
Retained
Size
Sieve
Sieve
(mm)
(mtze
SILT / CLAY
#200
0.075
SAND
FINE
#40
0.425
#200
0.07E
MEDIUM
#10
2.00
#40
0.425
COARSE
#4
4.75
#10
2.00
GRAVEL
FINE
0.75"
19
#4
4.75
COARSE
3"
76
0.75"
19
COBBLES
76 mm to 203 mm
BOULDERS
> 203 mm
ROCK
> 76 mm
FRAGMENTS
ROCK
>0.76 cubic meter in volume
INORGANIC SILTS, ROCK FLOUR, SANDY SILTS
OF SLIGHT PLASTICITY
60
INORGANIC SILTS, MICACEOUS OR
50
DIATOMACEOUS, FINE SANDY OR SILTY SOIL
INORGANIC CLAYS OF LOW PLASTICITY,
40
GRAVELLY, SANDY, OR SILTY CLAYS, LEAN
X
W
CLAYS
30
INORGANIC CLAYS OF HIGH PLASTICITY, FAT
H
CLAYS
U
20
ORGANIC SILTS AND ORGANIC SILTY CLAYS OF
Q
LOW PLASTICITY
d
10
7
ORGANIC CLAYS OF HIGH PLASTICITY
4
0
0 10 20 30 40 50 60 70 80 90 100
PEAT AND OTHER HIGHLY ORGANIC SOILS I LIQUID LIMIT (%)
GENERAL GUIDANCE FOR ENGINEERING PROPERTIES OF SOILS, BASED ON STANDARD
PENETRATION TEST (SPT) DATA
SANDY SOILS
SILTY & CLAYEY SOILS
Unconfined
Blow Counts
Relative
Friction Angle
Blow Counts
N
Density, %
.1, degrees
Description
P
N
Strength Clu,
Description
P
tsf
0-4
0 -15
Very Loose
< 2
< 0.25
Very soft
4-10
15 - 35
26 - 30
Loose
2-4
0.25 - 0.50
Soft
10-30
35 - 65
28 - 35
Medium Dense
4-8
0.50 - 1.00
Medium Stiff
30-50
65 - 85
35 - 42
Dense
8 - 15
1.00 - 2.00
Stiff
> 50
85 - 100
38 - 46
Very Dense
15 - 30
2.00 - 4.00
Very Stiff
> 30
> 4.00
Hard
Group Northwest, Inc.
Geotechnical Engineers, Geologists, &
Enviro nmental Scientists
13705 Bel -Red Road Bellevue, WA 98005
Phone (425) 649-8757 E-mail: info@geogrourpnw.com PLATE Al
HAND -AUGER BORING: HA-1
LOGGED BY SH LOG DATE: 9/20/2022
GROUND ELEV.
DEPTH
ft.
USCS
SOIL DESCRIPTION
SAMPLE
No.
Water
%
OTHER TESTS/
COMMENTS
SM
Silty Sand topsoil with grass, leaves, medium dense
-Probe 6" at 0.5'
1
S1
Probe 0-1" at 1.5'
2
SM
SAND, dense, yellow, dry, some gravel, approximately 5-10% fines
Total depth = 1.75 feet
3
Groundwater not encountered.
4
5
6
LOGGED BY SH
HAND -AUGER BORING: HA-2
LOG DATE: 9/20/2022
GROUND ELEV.
DEPTH
ft.
USCS
SOIL DESCRIPTION
SAMPLE
No.
Water
%
OTHER TESTS/
COMMENTS
Probe 6" at 0.5'
1
SM
Silty Sand with gravel, grass, leaves, medium dense, dry
2
Probe 1-0" at 1.5'
3
SAND dense yellow, dry, some gravel, approximately 5-10% fines
Total depth = 2.5 feet
4
Groundwater not encountered.
5
6
7
Group Northwest, Inc.
Geotechnical Engineers, Geologists, &
Environmental Scientists
HAND AUGER BORING LOGS
PROPOSED LANDSCAPING
18303 84T" PL W
EDMONDS, WASHINGTON