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41
February 26, 2007
-033-2
HWA Project No. 2007
Carolyn Belanich
7508 210'h Street SW
Edmonds, WA 98026
Attn: Mrs. Carolyn Belanich
Subject: GEOTECHNICAL INVESTIGATION
4-Unit Townhouse Development
7508 210t" Street SW
Edmonds Washington 98026
Dear Mrs. Belanich:
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RESU12
MAR 12 2007
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At your request, HWA GeoSciences Inc. (HWA) has undertaken and completed a
geotechnical investigation within your existing residential lot, for your proposed
townhouse development in Edmonds, Washington. This investigation has been
performed in support of the application required to obtain a building permit from the City
of Edmonds for the proposed 4-unit townhouse development at the subject site.
For the purposes of this investigation, HWA performed a review of the pertinent geologic
maps, conducted a site reconnaissance to observe local topographic features, excavated
5 shallow hand borings, and conducted 5 DCP (Dropweight Cone Penetrometer)
soundings to delineate in situ density/strength conditions of the site soils within the
footprint of the proposed development.
PROJECT LOCATION
The subject property consists of a developed 0-26 acre lot, located within the SW Y4,
Section 20, Township 27 N, and Range 4 E; situated at municipal address 7508 210"'
Street SW, in Edmonds, Washington (Snohomish County No. 00566900401002). The
approximate site location is depicted on Figure 1, the Project Site & Vicinity Map, —
PROPOSED DEVELOPMENT
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As currently proposed, the new development will consist of 4 townho
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units comprised of two duplex structures situated along the east and West
ly 22 feUL
sides of the lot served by a central shared driveway approximate
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M.
February 26, 2007
HWA Project No. 2007-033-21
wide, as shown on Figure 2, the Site & Development Layout Plan Map. Based on the
measurements depicted on the drawings, the planned townhouse units will occupy
roughly ± 1190 square feet each.
SITE OBSERVATIONS
Currently, an existing one-story wooden residential structure, built in 1953, occupies a
footprint area of approximately 1,544 square feet in the central portion of the 11,630
square foot lot- The townhouse development will require demolition of the existing
residential structure. The tot is relatively level in the front and ascends a slope in the
backyard to the south. Large trees are situated near the south property indicating lack of
disturbance in that area for many years. The configuration of the lot grading suggests
that the lot was leveled with fill to match the grade of 21& Street SW.
GEOLOGY
The published geologic map for the site area, "Composite Geologic Map ofthe Sno-King
Area" ' prepared by Booth, et al, 2004, shows that the site vicinity is underlain by Vashon
glacial till. Vashon till is the material which was deposited along the sole of the glacial
ice as lodgement till. it consists of an unsorted mixture of clay, silt, sand and gravel,
which is very dense, having been consolidated by the weight of greater than 2,000 feet of
ice. It is also known to contain scattered cobbles and boulders. This unit is locally"
referred to as "hardpan!', because of its induration and an appearance similar to concrete.
It has a very high strength and is suitable for foundations for structures. Till is relatively
impermeable, except where sandy zones are encountered. Generally, the till forms an
impervious layer below which surface water cannot penetrate. Where sand overlies the
till, water is often perched on top of the till.
SOELS
According to the Soil Conservation Map for Snohomish County (NRCS, online web soil
survey, 2007), the site is overlain by Alderwood — Urban Land complex, on 2 to
8 percent slopes. The Alderwood — Urban Land complex soils formed on glacial till
plains and contain at least 25% of Urban Land consisting of streets, buildings, parking
lots and other structures that obscure or alter the soils so that identification is not
possible. The runoff is slow and the erosion hazard is slight for these soils.
SITE EXPLORATION
On February 16'h, 2007, an HWA geologist conducted a limited shallow hand -exploration
program to evaluate near -surface conditions on the site. At that time, 5 hand borings:
were conducted to depths ranging from 3.0 to 4.8 feet, before refusing on coarse gravel or
cobbles. Site soil conditions were noted at each of the hand boring locations, which were
selected based on the location of proposed structures, as shown on the Site Plan provided
by the Architect. The approximate locations of our hand. borings are shown on Figure 2,
4-Unit Townhouse Development. 2
HWA GeoSciences. Inc.
February 26, 2007
HWA Project No. 2007-033-21
the Site & Exploration Plan Map. Hand boring logs were prepared from our
observations, and are presented on Figures 4 through 8- A legend of the terms and
symbols used on the exploration logs precedes them as Figure 3.
The hand auger borings at all locations were supplemented by utilizing a Dropweight
Cone Penetrometer (DCP) to check relative soil density/strength conditions. The DCP
consists of a steel extension shaft assembly, with a 60 degree hardened steel cone tip
attached to one end, which is driven into the subsoil by means of a sliding drop hammer.
The base diameter of the cone is 20 mm. The diameter of the shaft is 8 nim less than that
of the cone to ensure that at shallow penetration depths the resistance to penetration is
exerted on the cone alone. The DCP is driven by repeatedly dropping an 8 kg sliding
hammer from a height of 575 mm. The depth of cone penetration was measured after
each hammer drop and the soil shear strength is reported in terms of the DCP index. The
DCP index is based on the average penetration depth resulting from I blow of the 8 kg
hammer and is reported as millimeters per blow (mm/blow). The data obtained from the
DCP tests was correlated to approximate Standard Penetration Testing (SPT) blows per
foot, in order to evaluate the density/strength of the subgrade soils. The DCP data is
plotted on the appropriate Hand Boring Logs in Appendix A.
SOIL PROFILE
Typically, the near surface soils observed in the hand borings consisted of loose to
medium dense fill soils overlying weathered and unweathered glacial till soils. The soil
conditions are described briefly as follows:
Topsoil. Topsoil consisting of soft, dark brown, sandy silt, containing abundant rootlets
and organic material, was encountered at the surface at the location of all the hand
borings,. The topsoil layer encountered ranged from 0.33 to O.SO feet in thickness.
Undocumented Fill.- -Below the topsoil layer in all hand borings except 1411-5,
undocumented fill was encountered, consisting of loose to medium dense, gray to yellow
brown, sand with silt and gravel. This soil unit was only fully penetrated in HH-3 and
HH-4 where it was 4.4 and 3.4 feet thick, respectively. Hand borings, HH- I and HH-2
were terminated due to refusal on coarse gravel or cobbles and did not fully penetrate the
till. However DCP soundings indicate that dense native soils are as much as 8 to 10 feet
below existing grade at those locations. At the location of HH-5, native soil was
encountered below topsoil at an approximate depth of 0.4 below the existing ground
surface. Apparently, the fill thickens to the north towards 210dStreet SW.
Weathered Glacial Till — Weathered glacial till, consisting of medium dense/stiff,
reddish brown to gray, silty sand to sandy silt with gravel was encountered below the fill
at an approximate depth of 4.8 feet in HH-4; beneath old topsoil at 4.5 feet in HH-3; and,
beneath topsoil at 0.4 feet in HH-5. The thickness of this unit is unknown as it was too
deep to fully penetrate with hand tools. We expect, however, that the depth to dense silty
4-Unit Townhouse Development. 3 HWA GeoSciences Inc.
February 26, 2007
HWA Project No. 2007-033-21
sand till increases from south to north due to the amount of filling required to level those
areas nearer the street -
GROUND WATER
Ground water seepage was not observed in any of the hand borings. However, it is -
anticipated that ground water conditions will vary depending on the season, variations in
local subsurface conditions, and other factors. During wet season periods, it is possible
that ground water may become perched on the surface of the low permeability deposits at
other locations of this site.
GEOLOGIC HAZARDS
In accordance with the criteria contained in the City of Edmonds Code, Title 23-Natural
Resources; Chapter 23.80 — Geologically Hazardous Areas, the subject site is not situated
within an area designated as a potential erosion or landslide/steep slope or seismic
hazard.
The existing native soils consist of soils that were directly glacially consolidated, and are
dense. There are no steep slopes on the property and consequently no potential landslide
hazard.
CONCLUSIONS AND RECOMMENDATIONS
General
In summary, the soil conditions witffin the subject site proposed for the townhouse
development consists of dense, granular,. glacial till soils, overlain by loose to- medium
dense fill and topsoil layers at least 3.7 to 10 feet thick. The actual depth to dense, native,
soils at other locations within the development footprint will need to be verified in the
field during construction. In our opinion, the dense native sand (glacial till) will provide
adequate bearing for the residential foundation system. The topsoil and undocumented
fill materials are not recommended for foundation and floor slab support purposes.
Excavation and Temporary Shoring Requirements
Preparation for construction of conventional foundations will require the excavation and
removal of all undocumented fill beneath proposed footing and slab areas. Based on the
results of our investigation, these excavations will be atleast 4 feet deep or greater and
require excavation wall sloping and/or shoring to protect workers and existing structures
in accordance with Part N of WAC (Washington Administrative Code) 296-155. The fill
materials at the site classify as Type C soil. Unsupported excavations in Type C soils
must be inclined no steeper than 1!/2H: 1V (horizontal to vertical). Flatter slopes may be
required where ground water seepage occurs. Because of space constraints, we expect
shoring will be required along the east side of the excavation to protect the adjacent
4-Unit Townhouse Development. 4 HWA GeoSciences Inc.
February 26, 2007
RWA Project No. 2007-033-21
property, and underpinning will be needed on the south to protect the existing garage
foundation. Temporary excavation slopes should be protected from erosion, as
necessary, by covering the cui face with well -anchored plastic sheets. Maintenance of
safe working conditions, including temporary excavation stability, is the responsibility of
the contractor. Based on the soil conditions observed in our explorations, we anticipate
that the on -site soils can be excavated with conventional equipment such as backhoes and
loaders.
Foundations and Floor Slabs
Design Considerations: The proposed structure may be supported on footings bearing
directly on dense native soils, or properly compacted stru�tural fill, which may consist of
the existing on site undocumented fill soils that are removed and replaced under
controlled compaction. The recommended compaction level for structural fill placed
under footings and grade -supported slab levels is 95% Modified Proctor maximum dry
density (per ASTM D1557).
In our opinion, wall or column footings bearing in medium dense to dense, weathered
till could be designed for 4,000 pounds per square foot (psi) maximum allowable
bearing pressure. Footings bearing within structural fill placed over the dense to very
dense glacial till could be designed for g��ib �ftprp
ssures;.w: to 3POO PSL.�,
These values may be increased by 1/3 for short-term loads such as wind and seismic
eff�cts. It is not, however, recommended that foundations be designed for differing
bearing pressures, or be supported on dissimilar materials, to avoid potentially
undesirable differential settlements. Continuous footings should have a minimum
width of 18 inches, and column footings should have a minimum width of 24 inches,
regardless of bearing pressure corisiderations. Minimum f6oting widths may,
therefore, govern footing design. Footings should bear at least 24 inches below the
lowest adjacent exterior grade to provide for frost protection.
If footings are supported by structural fill, this fill should extend. beyond the outer
edges of the footings a minimum distance equal to the fill thickness below the
footing, measured at the level of the excavation base. If adjacent individual footings
are located at different elevations, it is recommended that the horizontal distance
between them be at least LS times the elevation difference between their bases.
Where adjoining continuous footings are at different elevations, the upper footing
should be stepped down to the lower footing.
Alternatively, if excavation of the existing undocumented fill is not desired, then the
structure could be founded on drilled piers, and a structural floor with crawl space may be
provided_ The actual embedment depth for pier foundation will vary dependent upon the
load capacity required by the structural engineer. For design purposes, we recommend
that the drilled pier or pile be considered to achieve its load capacity entirely from skin
friction effects. In this regard, we recommend that the allowable skin friction be taken as
4-Unit Townhouse Development. 5 HWA GeoSciences Inc.
February 26, 2007
HWA Project No. 2007-033-21
A-��pgfin the weathered and unweathered native glacial till soils below the level of the
fill ni��§. For example, aJ -foot diameter drilled concrete pile extending to a depth of
10 feet below existing groundsurface, would have an allowable load capacity of about
15 tons, assuming an average fill thickness of about 4 feet. The fill material should be
ignored in respect to providing vertical support capacity for pier foundations.
Foundation support might also be achieved through driven, small diameter (4 inch),
heavy wall (Schedule 40 or better), pipe or pin piles. Such piles driven to refusal in the
underlying glacial till deposit would have a range of load support capacities ranging from
about 4 to 8 tons. Actual bearing capacity.of driven pin piles should, however, be
verified in the field during construction. In our opinion, the medium dense to dense,
weathered to unweathered, till will provide adequate bearing for a properly designed
grade beam and pile foundation system that would transfer wall loads directly to bearing
soils and support the slab should the fill settle in the future.
Because of the potential long-term occurrence of shallow perched water over till soils, we
recommend that perimeter foundation drains are provided around all exterior footings, or
at or near the base of all pile supported grade beams. The footing drains and all surface
drains should be separately tight -lined to discharge to a sewer or storm basin- Surface
and roof drains should not be inter -connected to prevent the potential clogging and
flooding of the foundation drains
Floor slabs may be supported at grade on structural fill comp�cted to the requirements
indicated above- If grade -supported slabs are employed, they must be underlain by a
capillary break layer comprised of clean, uniform, open -graded, washed rock or pea
gravel, to prevent future slab dampness which could be detrimental to floor coverings.
This capillary break layer should be at least 6 inches thick and should be in contact with,
or provided with suitable drainage outlets to the perimeter foundation drain system. A
plastic vapor barrier should be placed on top of the capillary break layer to isolate the
slab concrete from this layer, and should consist of plastic sheathing such as Visqueen.
Construction Considerations: Footing foundation excavations should be trimmed neat
and the excavation bottoms should be carefully prepared in order to minimize the amount
of over -excavation that may otherwise be required. The ground surface where structural,
fill, foundations, or slabs are to be placed should be proofrolled�. or suitably probed to
determine the presence and approximate extent of any soft or unstable -areas. Proof -
rolling or probing should be performed under full-time observation of an HWA
representative. Any soils that cannot be adequately recompacted should be over -
excavated and the unsuitable materials removed and replaced with compacted structural
fill to a depth that will provide a stable base. W-;.d4'dcbffimend4hat:HWA be retained to
obsi�iii&'fj6ting excavations, and placement and compaction of structural fill Oflor to
pouring concrete.
4-Unit Townhouse Development. 6
HWA GeoSclences Inc.
February 26, 2007
HWA Project No. 2007-033-21
Assuming construction is performed as recommended herein, we estimate that the total
and differential settlements for foundations will be less than 1 -inch and '/2 -inch,
respectively.
Seismic Considerations
Should it be necessary for a development of this type to be designed for seismic
conditions, we anticipate that the new structures would be designed in accordance with
the 2003 International Building Code (IBC) standards. In this regard, for seismic design,
the site is considered Site Class C, as described in Section 1615.1 of the 2003 IBC. For
the site location, the design maximum considered spectral response acceleration at short
periods, Sp,, is 1-26g. The design maximum considered spect-al response acceleration at
1 second peri6d, S1, is 0.43g.
Soil liquefaction is a phenomenon wherein loose, saturated, granular deposits temporarily
lose strength and behave as a liquid in response to earthquake shaking. Based on our
observation of relatively dense material at or close to the base of the hand borings and the
apparent absence of regional ground water at shallow depths, we consider the potential
for seismic liquefaction on the site to be negligible. Hence, seisn:licaUy induced
liquefaction instability is not considered to be an issue for this site.
IErosion Control during Construction
Best Management Practices (BMP's) as described in City of Edmonds Code must be
followed. These measures include an erosion control plan that addresses, limiting
activity during wet periods, placement of a silt retention system on the eastern side of the
property, and proper disposal or recompaction of any material that is disturbed on the
site.
CONDITIONS AND LIMITATIONS
We have prepared this letter report for Mrs. Carolyn Belanich and her agents, for use in
construction and permitting of the proposed 4-unit townhouse development on the subject
lot. Experience has shown that soil and ground water conditions can vary significantly
over small distances. hiconsistent conditions can occur between explorations and may
not be detected by a geotechnical study of this scope.
Our scope of work did not include environmental assessments or evaluations regarding
the presence or absence of wetlands or hazardous substances in the soil, surface water, or
ground water at this site. HWA does not practice or consult in the field of safety
engineering. We do not direct the contractor's operations and we cannot be responsible
for the safety of personnel other than our own on the site; the safety of others is the
responsibility of the contractor. The contractor should notify the owner if any of the
recommended actions presented herein are considered unsafe.
0-0
4-Unit Townhouse Development. .7 HWA GeoSciences Inc.
February 26, 2007
HWA Project No. 2007-03 3-21
We appreciate the opportunity to be of service, and ftlLst that this report meets with your
requirements. However, if you have any questions regarding this report, or require
1
further assistance, please do no't hesitate to contact either of the undersigned at (425) 774-
0106.
Sincerely,
HWA GEOSCIENCES INC.
fEXPIRES 08124M76 '
Steven E. Greene, L.E.G. Lome A. Balanko, P.E.
Vice President/Senior Engineering Geologist President
Attachments: S G
Figure. I.:
Project Site Location and Vicinity Map
Figure 2:
Site Plan & Proposed Development Layout
Figure 3:
Legend of Symbols and Terms
Figure 4:
Log of HH-1 & DCP- I
Figure 5:
Log of HI-1-2 & DCP-2
Figure 6:
Log of HR-3 & DCP-3
Figure 7:
Log of HH-4 & DCP-4
Figure 8:
Log of HH-5 & DCP-5
4-Unit Townhouse Development 8 HWA GeoSciences Inc.
MAP NOT TO SCALE
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ULIMM', I HWAGEOSCIENCES INC.
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E PLAN & DEVELOPMENT LAYOUT
4 - UNIT TOWNHOUSE DEVELOPMENT
750821 YH ST. SW
EDMONDS WA 98026
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NORTH
FIGURE NO.
2007-033
r'DRILLING COMPANY: HWA Geosciences Inc. SURFACE ELEVATION: feet DATE STARTED: 02116/2007
DRILLING METHOD: Hand Bucket Auger DATE COMPLETED: 02116/2007
SAMPLING METHOD: dRAI3 LOGGED BY: D. Coltrane
LOCATION: See figure 2
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rootlets, moist. [UNDOCUMENTED FILL] 0
Hand hole terminated at 3.0 feet below ground surface due to
refusal on cobble.
No ground water seepage was observed.
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OTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and (herefora may not necessarily be indicative of other times and/or locations.
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BORING:
4 - Unit Townhouse Development HH-1
7508 21 Oth Street SW
1MGEOSCIENCHINC, Edmonds, Washington 98026 PAGE: I of I
PROJECT NO.: 2007-033-21 FIGURE: 4
BORING WITH OTHER PENETRATION TESTS 2007-033-2t.GPJ 2123tO7
or DRILLING COMPANY: HWA Geosciences Inc. SURFACE ELEVATION: :I: feet DATE STARTED: 0211612007
DRILLING METHOD: Hand Bucket Auger DATE COMPLETED: o2/1612007
SAMPLING METHOD: GRAB LOGGED BY: D. Coltrane
LOCATION: See figure 2
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SP Loose, yellow brown, SAND with silt and fine to mTdium S-2
SM gravel, rootlets, moist.
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brownish gray, SAND withsilt and fine tome( FlUm
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Hand hole terminated at 3.25 feet below ground surface due
to refusal on cobble.
No ground water seepage was observed.
1 5
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OTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
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BORING:
4 - Unit Townhouse Development HH-2
7508 21 Oth Street SW
HWAGEOSCIENCES INC. Edmonds, Washington 98026 PAGE: I of I
PROJECTmo.: 2007-033-21 FIGURE: 5
BORING WITH OTHER PENETRATION TESTS 2007-033-2l.GPJ 2123/07
01 DRILLING COMPANY: HWA Geosciences Inc. SURFACE ELEVATION:
:l: feet
DATE STARTED: 02/1612007
DRILLING METHOD: Hand Bucket Auger
DATE COMPLETED: 02/1612007
SAMPLING METHOD: GRAS
LOGGED BY: D. Coltrane
LOCATION: See figure 2
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rootlets, moist.
rWEATHERED TILLI
Hand hole terminated at 4.8 feet below g round surface due to
refusal on cobble.
No ground water seepage was observed.
OTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
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BORING:
4 - Unit Townhouse Development HH-3
7508 21 Oth Street SW
HWAGEOSCIENCESINC. Edmonds, Washington 98026 PAGE: 1 of 1
PROJECT NO.: 2007-033-21 FIGURE: 6
BORING WITH OTHER PENETRATION TESTS 2007-033,2 I.GPJ 2123107
OFDRILLING COMPANY: HWAGeosclences Inc. SURFACE ELEVATION: feet DATE STARTED: 02/1612007
DRILLING METHOD: Hand Bucket Auger DATE COMPLETED: 02116/2007
SAMPLING METHOD: GRAB LOGGED BY: D. Coltrane
LOCATION; Sea figure 2
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[UNDOCUMENTED FILL]
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SP Medium dense, gray, SAN D with silt and gravel, and trace
SM rootlets, moist. 8-3
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oxide mottling, moist. -0
Hand hole terminated at 4.2 feet below ground surface due to
refusal an cobble.
No ground water seepage was observed.
OTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
A
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5
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0 20 40 60 80 100
Water Content (%)
Plastic Limit 1 0 Liquid Limit
Natural Water Content
BORING:
4 - Unit Townhouse Development HH-4
=1 1 7 50 8 21 Oth Street SW
HWAGEOSCIENCESINC. Edmonds, Washington 98026 PAGE: 1 of I
PROJECT NO.- 2007-033-21 FIGURE: 7
BORING WITH OTHER PENETRATION TESTS 2007-033-2 I.GPJ 2123/07
DRILLING COMPANY: HWAGeosciences Inc. SURFACE ELEVATION:
feet
DATE STARTED: 02/16/2007
DRILLING METHOD: Hand Bucket Auger
DATE COMPLETED: 02116/2007
SAMPLING METHOD: GRAB
LOGGED BY: D. Coltrane
LOCATION: See figure 2
A Non -Standard Penetration Resistance (Blows per fool)
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(17.6 lb. weight, 22.6" drop)
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z
01 U)
(L
Q.
0
3:
D
0
W
DESCRIPTION
(0
W
W
IL :5
0
(D 0 10 20 30 40
50
Soft, dark brown, sandy SILT with rootlets, moist. A
FTOPSOIL1
Medium dense, orange brown, silly SAND with gravel, and S-1 A
rootlets, moist.
j: [WEATHERED TILL]
S-2
Till becoming gray brown, dense and less weathered. :>>
.............................. .........
0 : : . . i
Hand hole terminated at 3.0 feet below ground surface due to
refusal on cobble.
.............
No ground water seepage was observed. I . .
1 5
10
NOTE: This tog of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
I I . . I . . . . . - L-10
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1 0 Liquid Limit
Natural Water Content
BORNIG:
4 - Unit Townhouse Development HH-5
7508 21 Oth Street SW
IMAGEOSCIENCES INC. Edmonds, Washington 98026 PAGE: 1 of I
PROJECT NO.: 2007-033-21 FIGURE: 8
BORING WITH OTHER PENETRATION TESTS 2007-033-2l.GPJ 2123107
RELATIVE DENSITY OR CONSISTENCY VERSI IRRPT N_X/A I I IP
COHESIONLESS SOILS
COHESIVE SOILS
Density
N (blows/ft)
Approximate
Relative Density(-/.)
Consistency
N (blowsift)
_7P_P_r--'--1-
Undralned Shear
__71.
Strength (pso
4
15
4 250
Loose
4 to 10
35
Soft
2 to 4
250 - 500
Medium Dense
10 to 30
35 65
Medium Stiff
4 to 8
500 1000
Dense
30 to 60
65 85
stiff
8 to 15
1000 2000
Very Dense
overso
85 too
Very Stiff
16 1
USCS SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GROUP DESCRIPTIONS
Coarse
Gravel and
Clean Gravel
GW
Well -graded GRAVEL
Grained
Gravelly Gods
(little or no fines)
0, �'j �
Soi"s
bc
GP
Pocirly-graded GRAVEL
More than
Gravel with
GM
Silty GRAVEL
60% of Coarse
Fraction Retained
Fines (appreciable
on No. 4 Sieve
amount of fines)
GC
Clayey GRAVEL
Sand and
Clean Sand
Wall-9faded SAND
More than
Sandy Soils
(liffle or no fines)
SP
Poorly -graded SAND
50% Retained
50% or More
Sandwith
"I'l,
SMI
Silly SAND
on No.
ofCoarse
200 Sieve
Fraction Passing
Fines (appreciab�e
Size
No. 4 Sieve
amount of fines)
sc
Clayey SAND
ML
I SILT
Fine
Silt
Grained
and Liquid Limit
Clay Less than 50%
rganIc CLAY
MH I
Elastic SILT
50% or More
Silt Liquid Limit
Passing
and 50% or More
71�
CH
Fat CLAY
No. 200 Sieve
Clay
OH
Organic SILT/Organic CLAY
Size
Highly Organic Soils
PT
PEAT
COMPONENT DEFINITIONS
SIZE RANGE
'ou
' Bouldefs
Larger than 12 in
LCOMPONENT
Cobbles
3 in to 12 in
Gravel
el
3 in to No 4 (4.5mm)
Coarse gravel
. vat
3 in to 314 in
Fine gravel
314 In to No 4 (4.5mm)
Sand
No. 4 (4.6 mm)i to No. 200 (0.074 rnm)
Coarse sand
No. 4 (4.5 mm) to No. 10 (2.0 mm)
Meclurn send
No. 10 (2.0 mm) to No. 40 (0.42 mm)
Fine sand
No. 40 (0.42 mm) to No. 200 (0.074 mm)
Silt and Clay
Smaller than No. 200 (0.074mm)
TEST SYMBOLS
%F
Percent Fines
AL
Atterberg Limits: PIL = Plastic Limit
LL = Liquid Limit
CBR
California Bearing Ratio
CN
Consolidation
DO
Dry Density (pcf)
IDS
Direct Shear
GS
Grain Size Distribution
K
Permeability
MD
Moisture/Density Relationship (Proctor)
MR
Resilient Modulus
PID
Photolonization Device Reading
PP
Pocket Penetrometer
Approx, Compressive Strength (li
SG
Specific Gravity
TC
Triaxial Compression
TV
Torvane
Approx. Shear Strength (tsf)
LIC
Unconfined Compression
SAMPLE TYPE SYMBOLS
2.Ul OD Split Spoon (SPT)
(140 1b. hammer with 30 in, drop)
Shelby Tube
3-1/4'OD Split Spoon with Brass Rings
0
Small Bag Sample
Large Bag (Bulk) Sample
Core Run
ZNon-standard
Penetration Test
(3.U'OD split spoon)
GROUNDWATER SYMBOLS
Groundwater Level (measured at
time of drilling)
Groundwater Level (measured in well or
open hole after water level stabilized)
COMPONENT PROPORTIONS
PROPORTION RANGE
DESCRIPTIVE TERMS
< 5%
Clean
5-12%
Slightly (Clayey, Silty, Sandy)
12-30%
Clayey, Silty, Sandy, Gravelly
30 - 6DO/o
Very (Clayey, Silty, Sandy, Gravelly)
Components are arranged In order of increasing quantities.
NOTES: Soil classifications presented on exploration logs are based on visual and laboratory observation.
Soil descriptions are presented in the following general order: MOISTURE CONTENT
Densityloonsistency, color, moiffner (if any) GROUP NAME, a"ons to group name (ilany), moisfure DRY Absence of moisture, dusty,
content Proportion, gradation, and angularity otconsfituents, additional comments. dry to the touch.
(GEOLOGIC INTERPRETATICAll MOIST Damp but no visible water,
Please refer to the discussion In the report text as well as the exploration logs for a more WET Visible free water, usually
complete description of subsurface conditions. soll Is below water table.
=A 4 - Unit Townhouse Development LEGEND OF TERMS AND
7508 21 Oth Street SW SYMBOLS USED ON
HWAGEOSCIENCESINC Edmonds, Washington 98026 EXPLORATION LOGS
LEGEND 2007-033-2l.GPJ 2123107 PROJECT NO.: 2007-033-21 FIGURE! 3