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� DEVELOPMENT PLANNING
CITY OF RENTON
MAY 2 1 2004
RECEIVED
Geotechnical Engineering Report
Union Avenue short plat
Renton, Washington
For
Gough Development, Inc.
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Cornerstor�e 17625-130�Ave. NE, C102,Woodinville, WA 98072
Phone: 425•8441977
� G e��e�h�n i�al�. �nCr, Fax: 425-844-198T
April 8,2004
Gough Development, Inc.
c/o Davis Consulting,Inc.
27013 Pacific Highway South,
, PMB#353
Des Moines,WA 98198
Geotechnical Engineering Report
Union Avenue short plat
Renton,Washington
CG File No. 1627
Dear Mr.Davis:
�
INTRODUCTION
� This report presents the results of our geotechnical engineering investigation at your proposed residentia]
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Map in Figure 1.
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You have requested that we complete this report to evaluate subsurface conditions and provide
� recommendations for site development. For��use in preparing this report, we have been provided with
an electronic site survey,prepared by Anderson Surveyors.
PROJECT DESCRIPTION �
� The uregularly-shaped parcel is about 314 acre in size. We understand that the current plan is to constiuct
six single-family residences and an access roadway within the prope�rty. We have not been provided with
i a grading plan, but understand that site grading will include minor cuts and fills. We understand that
Honey Creek runs near a portion of the southern and western property lines, and that a 50-foot buffer has
_I been established from the creek.
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Geotechnical Engineering Report
Union Avenue short plat
Apri18,2004
CG File No. 1627
Page 2
SCOPE
'The purpose of this study is to explore and characterize the subsurface conditions and present
recommendarions for site development. Specifically, our scope of services as ouflined in our Services
Agreement, dated March 29,2004,includes the following:
1. Review available geologic maps of the site.
2. Explore the subsurface soil and ground water conditions with a subcontiracted backhoe.
3. Provide recommendations for site preparation and grading.
I 4. Provide foundation recommendations for the structures.
5. Provide recommendations for minim;��ng disturbance to creek during construction
6. Document our observations,conclusions, and recommendations in a written report.
SITE CONDITIONS
Surface Conditions
The project site is about 3/4 acre in size and has maximum dimensions of approximately 259 feet in the
east-west direction and 164 feet in the north-south direction. The site is bordered by Union Avenue NE to
the east, Honey Creek to the west and south, existing commercial property to the south, and existing
residential property to the north. A layout of the project site is shown on the Site Plan in Figure 2.
The site is generally flat-lying to gently sloping. The overall grade of the site slopes downward to the
west and south, towazd the steep-banked Honey C�eek. The site contains grassy areas, witli areas of
brush, blackberries, and small- to medium-sized trees. An existing residence is located in the central
' portion of the site, with a detached shed toward the west end. These structures are planned to be
demolished during construcrion.
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Geology
Most of the Puget Sound Region was affected by past intrusion of conrinental glaciation. The last period
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' of glaciation,the Vashon Stade of the Fraser Glaciarian, ended approximately 10,000 to 11,000 years ago.
Many of the geomorphic features seen today are a result of scouring and overriding by glacial ice. During
� the Vashon Stade, the Puget Sound region was overridden by over 3,000 feet of ice. Soil layers
overridden by the ice sheet were compacted to a much greater extent than those that were not. Part of a
� Cornerstone Geotechnical, Inc.
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Geotechnical Engineering Report
Union Avenue short plat
Apri18, 2004
CG File No. 1627
Page 3
typical glacial sequence includes recessional outwash sand underlain by glacial till. Glacia] till is an
unsorted mixture of sand, silt, and gravel that is deposited at the bottom of the glacier, which is
commonly referred to as "hardpan". The glacial till has been consolidated under the weight of the
c�ntinental glaciers. The till e�chibits both high strength and low permeability.
�ur site explorations encountered recessional outwash or aliuvium, glacial till, and advance outwash.
The alluvium consists of sediment placed as a point bar deposit by Honey Creek. Advance outwash
consists of sand and gravel deposited by glacial meliwater streams in front of the advancing glacier.
Explorations
Subsurface conditions were explored at the site on April 6, 2004, by excavating four test pits with a
backhoe. The test pits were excavated to depths of 6.0 to 12.0 feet below the ground surface. The
explorarions were located in the field by a geologist from this firm who also examined the soils and
geologic conditions encountered, and main#ained logs of the test pits. The approximate locations of the
test pits are shown on the Site Plan in Figure 2. The soils were visually classified in general accordance
with the Unified Soil Classification System,a copy of which is presented as Figure 3. The logs of the test_
pits are presented in Figures 4 and 5.
Subsurface Conditions
A brief description of the conditions encountered in aur explorations is included below. For a more
detailed description of the soils encountered,review the test pit logs in Figures 4 and 5.
Our explorations typically encountered a surficial ]ayer of topsoil that averaged less than 1 foot in
thiclmess. Test Pit 4 encountered 2 feet of surficial fill material that contained asphalt, concrete, and
metal fragments overlying topsoil. The topsoil consisted of loose, dark brown silty sand with organics.
Underlying the topsoil, a weathered soil horizon, approximately 1 to 2 feet in thickness, was encountered
in the explorations. The weathered horizon consisted of red-brown, loose to medium dense, sand or silty
sand with roots and gravel. Below the weathered horizon, Test Pits 3 and 4 encountered generally
medium dense to dense sand with varying amounts of silt,while Test Pits 1 and 2, Iocated in the vicinity
of Honey Creek, encountered gravelly sand. The soil color was predominantly gray with rust mottling at
depth, and the soil types were mostly alluvium/recessional outwash,with advance outwash encountered in
Test Pit 4. Test Pits 1,2 and 3 then encountered very dense silty sand with gravel. This soil is interpreted
as glacial till. Test Pits 1 and 3 were completed in this till. Below the rill, Test Pit 2 encountered gray
� Cornerstone Geotechnical, Inc.
Geotechnical Engineering Report
Union Avenue short plat
April 8, 2004
CG File No. 1627
Page 4
fine to medium sand with silt laminae. This soi] is interpreted as advance outwash. Test Pit 4 was
completed in very stiffrust-stained gray silt.
Hydrologic Conditions
Ground water seepage was encountered in Test Pit 4 at a depth of 10.5 feet. We consider this water to be
perched on the underlying siit layer. We also encountered rust-staining to various depths in our
explorations. The mottled zone is also a sign of perched water during the wet season. The thickness of
the mottled layer does not indicate full saturation of the unit. The dense to very dense till or very stiff silt
found at or below the mottled zone are considered poorly draining. During the wetter times of the year,
we expect perched water conditions will occur as pockets of water on top of layers of low permeable
soils. Perched water does not represent a regional ground water "table" within the upper soil horizons. ,
Volumes of perched ground water vary depending upon the time of year and the upslope recharge
conditions. Although wet conditions can exist due to perched ground water, flow volumes are expected to
be low.
GEOLOGIC HAZARDS
Landslide Hazards
The subject site is underlain by dense to very dense glacia] soils at shallow depths. These soils have very
high shear strength and high resistance against slope failures.
There is a potential that the surficial soils on the banks of Honey Creek could slough over time,
However, we did not observe any active evidence of sloughing, and the vegetation on the bank is
considered mature.
Erosion Iiazard
The erosion hazard criteria used for determination of affected areas include soil type, slope gradient,
vegetarion cover, and ground water conditions. The erosion potential is related to vegetative cover and
the specific surface soil types (group classification), which are related ta the underlying geologic units.
Over the majoriiy of the site we consider the erosion hazard to be slight with vegetative cover in place
and moderate when stripped of vegetation. The sloping bank of Honey Creek is considered to have
moderate potenrial for erosion when covered with vegetation and high when stripped of vegetation. Best
management practices (BMPs) and applicable codes should be followed during site grading to limit
Cornerstone Geotechnical, Inc.
Geotechnical Engineeri.ng Report
Union Avenue short plat
April S,2004
CG File No. 1627 �
Page 5
potenrial for erosion. We do not expect this site will require unusual or extreme erosion management
methods.
Liquefaction Hazard
The Puget Sound region is classified as Seismic Zone 3 by the Uniform Building Code (iJBC). Hazards
associated with seismicity include liquefaction. The type of soil most susceptible to liquefaction during
an earthquake is a saturated, loose, fine- to medium-grained sand deposi� A loose, saturated sand
deposit,when subjected to vibration, tends to compact and decrease in volume. The site subsurface soils
are dense to very dense glacisl till and glacially-consolidated advance outwash, which are not prone to
liquefacrion.
I CONCLUSIONS AND RECOMMENDATIONS
' General
It is our opinion that the site is comparible with the planned development. The underlying medium dense
� to very dense soils are capable of supporting the planned structtues and pavements. We recommend that
the foundarions for the s�uctures extend through any topsoil, loose, or disturbed soils, and bear on the
underlying medium dense to very dense,native soils, or on structural fill extending to these soils. Based �'
on our site explorations, we anricipate these soils will generally be encountered at typical footing depths.
It is ovr opinion that the 50-foot creek buffer will provide an acceptable geotechnical setback from the top
of the slope. I
The soils likely to be exposed during construction are extremely moisture sensitive and will distuxb easily
when wet or during wet conditions. We recommend that construcrion take place during the drier summer I!
months, if possible. If construction ta.kes place during the wet season, addirional expenses and delays ;
should be expected due to the wet conditions. Additional expenses could include additional depth of site �
stripping, export of on-site soil,the imp�rt of clean granular soil for fill, and the need to place a blanket of i
rock spalls in the access roads and paved areas prior to placing structural fill.
Creek Disturbance
The creek buffer planned should minimize disturbance to Honey Creek. We recommend best
management practices be used and erosion control measures correspond to appropriate local and state
guidelines. Silt fencing should be constructed and properly embedded downslope from all disiurbed
areas. Stockpiles that will be exposed for extended periods o£time in the wet season should be covered
Cornerstone Geotechnical, Inc.
Geotechnical Engineering Report
Union Avenue short plat
Apri18,2004
CG File No. i627
Page 6
with plastic. Starm water should be routed to an appropriate temporary storm water handli.ng system.
Outfall from this system should be dispersed through vegetated areas rather than in concentrated flows
into the creek. Discharge from the temporary storm water system should be carefully monitared daily. If
discharge water is found to concentrate or have a silt content exceeding regulatory limits, conections or
improvements to the storm water system should be implemented immediately.
Site Preparations and Grading
The first step of site preparation should be to strip the vegetation, fill, topsoil, or loose soils to expose
medium dense to very dense native soils in pavement and building areas. This material should be
removed from the site, or stockpiled far later use as landscaping fill. The resulting subgrade should be
compacted to a firm,non-yielding condition. Areas observed to pump or weave should be repaired prior
to placing hard surfaces.
The on-site glacial till,or other silty soil likely to be exposed during construction, is considered extremely
moisture sensitive,and the surface will disturb easily when wet. We expect these soils would be difficult,
if not impossible, to compact to structural fill specifications in wet weather. We recommend that
earthwork be conducted during the drier months. Additional expenses of wet weather or winter I
cons�-uction could include extra excavation and use of imported fill or rock spalls. During wet weather,
alternative site preparation methods may be necessary. These methods may include utilizing a smooth-
bucket hackhoe to complete site stripping and diverting construction traffic around prepared subgrades.
Disturbance to the grepared subgrade may be minimized by placing a blanket of rock spalls or imported
sand and gravel in traffic and roadway areas. Cutoff drains or ditches can also be helpfu] in reducing '
grading costs during the wet season. These methods can be evaluated at the time of construction.
Structural Fill
General: All fill placed beneath buildings, pavements or other settlement sensitive features should be
placed as structural fill. Structural fill,by defuution, is placed in accordance with prescribed methods and
standards, and is monitored by an experienced geotechnical professional or soils technician. Field-
monitoring procedures would include the perf�rmance of a representative number of in-place density tests
to document the attainment of the desired degree of relative compaction.
Materials: Imported structural fill should consist of a good quality, free-draining granular soil, free of
organics and other deleterious material, and be well graded to a maximum size of about 3 inches.
Cornerstone Geotechnical, Inc.
Geotechnical Engineering Report
Union Avenue short plat
Apri18, 2004
CG File No. 1627
Page 7
Imported,aIl-weather structural fill should contain no more than 5 percent fines (soil finer than a Standard
U.S.No. 204 sieve),based on that fracrion passing the U.S. 3/4-inch sieve.
The on-site soils should be suitabte for use as s�uctural fill but their use will be dependent on moisture
content conlrol. Some drying of the native soils may be necessary in order to achieve compaction.
During warm, sunny days this could be accomplished by spreading the material in thin lifts and
compacting. Some aeration andlor addition of moisture may also be necessary. We expect that
compaction of the native soils to structural fill specifications would be difficult, if not impossible, during
wet weather.
Fill Placement: Following subgrade preparation, placement of the structtual fill may proceed. Fill
should be placed in 8- to 10-inch-thick uniform Iifls, and each lift should be spread evenly and be
thoroughly compacted prior to placement of subsequent lifts. All structural fill underlying building areas,
and within a depth of 2 feet below pavement and sidewalk subgrade, should be compacted to at Ieast 95
percent of its maximum dry density. Maximum dry density, in this report, refers to tbat density as
determined by the ASTM D 1557 compaction test procedure. Fill more than 2 feet beneath sidewalks and
pavement subgrades should be compacted to at least 90 percent of the maximum dry density. The �
moisture content of the soil to be compacted should be within about 2 percent of optimwn so that a �
readily compactable condition exists. It may be necessary to overexcavate and remove wet surficial soils ,
in cases where drying to a compactable condition is not feasible. All compaction should be accomplished i
by eqtupment of a type and size sufficient to attain the desired degree of compaction. �
Temporary and Permanent Slopes
Temporary cut slope stability is a function of many factors, such as flie type and consistency of soils, ��
depth of the cut, surcharge loads adjacent to the excavation, length of rime a cut remains open, and the �
presence of surface or ground water. It is exceedingly difficult under these variable conditions to estimate ��,
a stable temporary cut slope geometry. Therefore, it should be the responsibility of the contractor to ��
maintain safe slope configurations, since the contractor is continuously at the job site,able to observe the
nature and condition of the cut slopes, and able to monitor the subsurface materials and ground water
conditions encountered.
We anticipate temporary cuts for installation of utilities. For planning purposes, we recommend that
temporary cuts in the near-surface weathered soils be no greater than 1 Horizontal to 1 Vertical (1H:1V).
Cornerstone Geotechnical, Inc.
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Geotechnical Engineering Report
Union Avenue short plat
April 8, 2004
CG File No. 1627
Page 8
Cuts in the dense to very dense soils may stand at a 0.75H:1 V inclination or possibly steeper. If ground
water seepage is encountered,we would expect that flatter inclinations would be necessary.
We recommend that cut slopes be protected from erosion. Measures taken may include covering cut
slopes with plasric sheeting and diverting surface nuioff away from the top of cut slopes. We do not
recommend vertical slopes for cuts deeper than 4 feet, if worker access is necessary. We recommend that
cut slope heights and inclinations conform to local and WISHA/OSHA standards.
Final slope inclinations for structura] fill and the cuts in the native soils should be no steeper than 2H:1V.
Lightly compacted fills or common fills should be no steeper than 3H:1V. Common fills are defined as
fill material with some organics that are "tracla�olled" into place. They would not meet the compaction
specification of structural fill. Final slopes should be vegetated and covered with s�aw or jute netting.
The vegetation should be maintained until it is established.
Foundations
Convenrional shallow spread foundations should be founded on undisturbed, medium dense to very
dense, glacial soils, or be supported on structural fill extending to those soils. If the soil at the planned
bottom of footing elevation is not medium dense to very dense, it should be overexcavated to expose
suitable bearing soil, and the excavation should be filled with structural fill, or the footing may be
overpoured with extra concrete. i
Footings should extend at least 18 inches below the lowest adjacent finished ground surface for frost
protection and bearing capacity considerarions. Minimum foundation widths of 12 and 18 inches should
be used for continuous and isolated spread footings, respectively. Standing water should not be allowed I
to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation
excavation prior to placing concrete. �
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For foundauons constructed as outlined above, we recommend an allowable design bearing pressure of ',
2,000 pounds per square foot (psfl be used for the footing design. Uniform Building Code (UBC) �
guidelines should be followed when considering short-term transitory wind or seismic loads. Potential �
foundation settlement using the recommended allowable bearing pressure is estimated to be less than 1-
� inch total and '/Z-inch differential between footings or across a distance of about 30 feet: Higher soil
bearing values may be appropriate for footings founded on unweathered till, and with wider footings. I
These higher values can be determined after a review of a specific design.
Cornerstone Geotechnical, inc.
Geotechnical Engineering Report
Union Avenue short plat
April S,2004
CG File No. 1627
Page 9
Lateral loads can be resisted by friction between the foundation and subgrade soil, and by passive soil
resistance acting on the below-grade portion of the foundation. For the latter, the foundation must be
poured "neat" against undisturbed soil or backfilled with clean, free-draining, compacted structural fill.
Passive resistance may be calculated as a hiangular equivalent fluid pressure distribution. We
recommend that an equivalent fluid density of 200 pounds per cubic foot (pc� be used to calculate the
allowable lateral passive resistance for the case of a level ground surface adjacent to the footing. An
allowable coefficient of friction between footings and soil of 0.50 may be used, and should be applied to
the vertical dead load only. A factor of safety of 2.0 has been applied to the passive pressure to account
for required movements to generate these pressures. The friction coefficient does not include a factor of
safeiy.
Slabs-On-Grade
Slab-on-grade areas should be prepared as recommended in the Site Preparation and Grading
subsection. Slabs should be supported on medium dense to very dense native soils, or on structural filZ
extending to these soils. Where moisture control is a concem,we recommend that slabs be underlain by 6
inches of free-draining coarse sand or pea gravel for use as a capillary break. A suitable vapor barrier,
such as heavy plasric sheeting, should be placed over the capillary break.
Drainage �'
We recommend that runoff from impervious surfaces, sucn as roofs, driveway and access roadways, be �
collected and routed to an appropriate storm water discharge system. Fina1 site grades should allow for
drainage away from any buildings. We suggest that the finished ground surface be sloped at a gradient of '
3 percent minimum for a distance of at least 10 feet away from the buildings. Surface water should be
collected by permanent catch basins and drain Iines, and be discharged into a storm drain system.
Footing drains should be used around all of the structures where moishue control is important. The I
underlying till or silty soils will pond water that may accumulate in the crawlspace. It is good pracrice to ,
use footing drains installed at least 1 foot below planned finished floor slab or crawlspace elevation to �
provide drai.nage for the crawlspace. At a minimum,the crawlspace should be sloped to drain to an outlet
tied to the drainage system.
Where used, footing drains should consist af 4-inch-diameter, perforated PVC pipe that is surrounded by
free-draining material, such as pea gravel. Footing drains should discharge into tightlines leading to an
Cornerstone Geotechnical, Inc,
Geotechnical Engineering Report
Union Avenue short plat
April 8,2004
CG File No. 1627
Page 10
appropriate collection and discharge point. Crawlspaces shotald be sloped to drain, and a positive
connection should be made into the foundation drainage system. For slabs-on-grade, a drainage path
should be provided fr�m the capillary break material to the footing drain system. Roof drains should not
be connected to wall or footing drains.
Utilities
Our explorations indicate that specific deep dewatering will not be needed to install utilities. Anricipated
ground water is expected to be handled with pumps in the �enches. We also expect that some ground
water seepage may develop during and following the wetter times of the year. We expect this seepage to
mostly occur in pocicets. We do not expect significant volumes of water in these excavations.
The soils likely to be exposed in utility trenches after site stripping are considered moderately to highly
moishue sensitive. We recommend that they be considered for trench backfiIl during the drier portions of
the year. Provided these soils are within 2 percent of their optimum moisture content, they should be
suitable to meet compaction specifications. During wet weather, it may be difficult to achieve
compaction specifications and soil amendment with kiln dust or cement may be needed to achieve proper
compaction with the on-site materials. ,
Pavement
The performance of roadway pavement is crirically related to the conditions of the underlying subgrade.
We recommend that the subgrade soils within the roadways be treated and prepared as described in the
Site Preparation �nd Grading subsection of this report. Prior to placing base material, the subgrade '
soils should be cornpacted to a non-yielding state with a vi-bratory roller compactor and then proof-rolled
with a piece of heavy construction equipment, such as a fully-loaded dump iruck. Any areas with
excessive weaving �r fle��ing should be overexcavated and recompacted or replaced with a structural fill�
ar cntshed rock placed and compacted in accordance with recommendations provided in the Structural
Fill subsection of this report. '
MONITORING
We should be retained to provide monitoring and consultation services during construction to confirm that
the conditions encountered aze consistent with those indicated by the explorations, and to provide
recommendations for design changes, should the conditions reveaIed during the work differ from those
Cornerstone Geotechnical, Inc.
Geotechnical Engineering Report
Union Avenue short plat
Apri18, 2004
CG File No. 1627
Page 11
anricipated. As part of our services, we would also evaluate whether or not earthwork and foundation
installation acrivities comply with contract plans and specificarions.
USE OF THIS REPORT
We have prepared this report for Gough Development and its agents, for use in planning and design of
this project. The data and report should be provided to prospective contractors for their bidding and
estimating purposes,but our report, conclusions and interpretations should not be construed as a warranty
of subsurface conditions.
The sc�pe of our work does not include services related to construction safety precautions, and our
recommendarions are not intended to direct the contractors' methods, techniques, sequences or
procedures, except as specificaAy described in our report, for consideration in design. There are possible
variations in subsurface conditions. We recommend that project planning include contingencies in budget
and schedule, should areas be found with conditions that vary from those described in this report.
Within the limitations of scope, schedule and budget for our work, we have strived to take care that our
work has been completed in accordance with generally accepted practices followed in this area at the time
this repart was prepared. No other condirions, expressed or implied, should be wzderstood. I
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Cornerstone Geotechnical, Inc.
i
Geotechnical Engineering Report
Union Avenue short plat
April 8,2004
CG File No. 1627
Page 12
We appreciate ttie opporhinity to be of service to you. If there are any questions concerning this report or
if we can provide additional services,please call.
Sincerely,
Cornerstone Geotechnical, Inc.
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Jeff Laub
Project Geologist
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Cornerstone Geotechnical, Inc.
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Unified Soil Classification System
MAJOR DIVISIONS GROUP GROUP NAME
SYMBOL
GRAVEL CLEAN GRAVEL GW WELL-GRADED GRAVEL,FINE TO COARSE GRAVEL
COARSE-
GRAINED MORE THAN 50%OF GP POORLY-GRADED GRAVEL
COARSE FRACTION
SOILS RETAINED ON N0.4 GRAVEL
SIEVE WITH FINES GM si�N�w�v��
GC CLAYEY GRAVEL
MORE THAN 5D°h
RETAINED ON SAND CLEAN SAND SW WELL-GRADED SAND,FINE TO COARSE SAND
number 200 SIEVE
SP POORLY-GRADED SAIVD
MORE THAN 5Q96 OF
COARSE FRACTION SAND
PASSES NO.4 SIEVE �TH FINES SM SII.TY SAND
SC CLAYEY SAND
SILTAND CLAY INORGANIC ML SILT
FINE-
GRAINED LIQUID UMIT CL C�AY
LESS THAN 509b
SOILS ORGANiC
OL ORGANIC SILT, ORGANIC CLAY
MORETHAN 50°k SIITAND CLAY �
PASSES N0.200 SIEV INORGANIC MH SILT OF HIGH PLASTICITY,ELASTIC SILT �
LIQUID LIkA1T CH CU1Y OF HIGH PLASTICITY,FAT CLAY
509b OR MORE
ORGAN{C OH ORGANIC CLAY,ORGANIC S1LT
HIGHLY ORGANIC SOILS pT PEa,r
NOTES:
SOIL MOISTURE MODIFIERS
1) Field classification is based on Dry-Absence of moPsture, dusry, dry
visual examination of soil in general to the touch
accordance with ASTM D 2488-83.
2) Soil classification using laboratory Moist-Damp, but no visible water
j tests is based on ASTM D 2487-83. W�t-Visible free water or saturated,
3) Descriptions of soil density or usually soil is obtained from
,� consistency are based on below water table
� interpretation �f blowcount data,
visual appearance of soils, and/or
test data.
Cornerstone Phone:(425)844-1977 Unified Soil Classification System
�
( ;� Ge�teCh n�Ca�� �nC. Fax:(425)844-1987 'I
17625-130th Ave NE,C-102•Woodinville,WA• 98072 Figure 3
1
� LOG OF EXPLORAT}ON
DEPTH USC SOIL DESCRIPTIOfV
TEST PIT ONE
0.0-1.0 SM DARK BROWN SILTY SAND WITH GRAVEL,ORGANICS AND ROOTS(LOOSE, MOIST}
(TOPSOIL)
1.0-2.Q SP RED-6ROWN FINE TO MEDfUM SAND WITH GRAVEL AIVD ROOTS (LOOSE TO
MEDIUM DENSE,MOIST)(WEATHERED ALLUVIUM)
2.0-3.0 SP BROWN FINE TO MEDIUM SANq WITH GRAVEL(MEDIUM DENSE,MbIST)
3.5-5.0 SW �RAY (WITH RUST STAINING AT 4.5 FEET) GRAVELLY FINE TO COARSE SAND
(MEDIUM DENSE TO DENSE,MOIST)(ALLUVIUM/RECESSI�NAL OUTWASH)
5.0-6.0 SM GRAY SILTY FINE TO MEDIUM SAND WITH GRAVEL(VERY DENSE,MOIST)(TILL)
SAMPLES WERE C�LLECTED AT 2.0,3.5 AND 6.0 FEET
GROUND WATER SEEPAGE WAS NOT ENCAUNTERED
TEST PIT CAVING WAS NOT OBSERVED
TEST PIT WAS COMPLETED AT 6_0 FEET ON 416/04
TEST PIT7W0
0.0-1.0 SM - DARK BROWN SILTY SAND WITN GRAVEL, ORGANICS, ROOTS AND CLAY PIPE
FRAGMENTS{LOOSE,MOIST)(TOPSOIUFILL)
7.0-2.0 SP RED-BRaWN F1NE TO MEDfUM SAND WITH GRAVEL A►VD ROOTS (LOOSE TO
MEDIUM DENSE,MOIST){WEATHERED ALLUVIUM)
2.0-B.0 SW GRAY(WITH RUST STAINING AT 7.0 FEET)GRAVELLY FINE TO COARSE SAND WITH
SCATTERED COBBLES UP TO 12 INCHES IN DIAMETER(MEDIUM DENSE TO DENSE,
MOIST)(ALLUVIUM/RECESSIONAL OUTWASH)
8.0-9.0 SM GRAY SILTY FINE TO MEDIUM SAND WITH GRAVEL(VERY DENSE,MOIST)(TILL)
9.0-1D.0 SP-SM GRAY FINE TO MEDIUM SAND WITH SILT LAMINAE AND TRACE GRAVEL (VERY
DENSE,MOIST)(ADVANCE OUTWASH)
SAMPLE WAS COLLECTED AT 10.0 FEET
GROUND WATER SEEPAGE WAS NOT ENCOUNTERED
TEST P1T CAVING WA5 NOT OBSERVED
TEST PIT WAS COMPLETED AT 10.0 FEET ON 4/6/04 �
TEST PIT THREE
0.0-0.2 SM �ARK BfiOWN GRAVELLY SILTY SAND WITH ORGANICS AND ROOTS (LOOSE,
MOIST)(TOPSOIUGRAVEL FILL}
0.2-1.0 SM RED-BROWN SILTY SAND WITH GRAVEL AND TRACE ROOTS (LOOSE TO MEDIUM
DENSE, MOIS�(WEATHERED ALLUVIUM)
1.0-2.5 SM BROWN-GRAY SILTY SAND WITH GRAVEL AND TRACE ROOTS (MEDIUM DENSE,
MOlST}
2.5-4.5 SP-SM GRAY (WITH RUST STAINING AT 4.0 FEEf) FINE TO MEDIUM SAND WITH 51LT,
TRACE GRAVEL AND TRACE ROOTS{MEDIUM DENSE,MOIST)(ALLUVIUM)
4.5-7.0 SM GRAY SILTY FINE TO MEDIUM SAND WiTH GRAVEL (DENSE TO VERY DENSE,
MOIST)(TILL)
SAMPLE WAS COLLECTED AT 3.0 FEET
GROUND WATER 5EEPAGE WAS iVOT ENCOUNTERED
TEST PIT CAVING WAS NOT OBSERVED
TEST PIT WAS COMPLETED AT 7.0 FEET ON 4/6/04
CORNERSTONE GEOTECHNICAL, INC.
FILE NO 1627
FIGURE 4
• LOG OF EXPLORATION
DEPTN USC SOIL DESCRIPTION
TEST PIT FOUR
0.0-2.0 SW GRAY GRAVELLY SAND WITH ASPHALT CHUNKS, METAL FRAGMENTS AND
CONCRETE(LOOSE,NfO1ST)(FILL)
2.D-3.0 5M DARK BROWN SILTY SAND WITH ORGANICS AND ROOTS (LOOSE, MOIST)
(TOPSOIL)
3.0-4.5 5M RED-BROWN SIITY SAND WITH GRAVEL AND ROOTS (LOOSE TO MEDIUM DENSE,
MOIS�(WEATHERED OUTWA3H)
4.5-6.5 SP-SM RUST-STAINED GRAY FINE TO MEDIUM SANQ WITH 51LT (MEDIUM DEfVSE TO
DENSE,MOIST)(ADVANCE OUTWASH)
6.5-'10.5 SP-SM BROWN-GRAY FINE TO MEDIUM. SAND WITH SILT (DENSE, MOIST TO WET)
(ADVANCE OUTWASH)
10.5-12.0 ML RUST-STAINED GRAY SILT(VERY STIFF, MOIST 70 WET)
SAMPLES WERE COLLECTED AT 7.5 AND 11.0 FEET
SLIGHT GROUND WATER SEEPAGE WAS ENCOUNTERED AT 10.5 FEET
TEST PIT CAVING WAS NOT OBSERVED
TEST PIT WAS COMPLETED AT 12.0 FEET ON M6104
CORNERSTONE GEOTECHNICAL, INC.
FILE NO 1627
FIGURE 5