HomeMy WebLinkAbout03247 - Technical Information Report - Geotechnical i
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Cornerstone
Geotechnical , Inc.
' Geotechnical Engineering Report
Sunset Boulevard Plat
Rentoo, Washington
Gough Development, Inc.
I
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��Ci�Y OF E ONNING
JUL 1 5 2004
RECEIVED
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Cornerstone 17625-130�'Ave. NE, C102, Woodinville, WA 98072
Phone: 425-844-1977
� G eotech n ical� �nCi. Fax: 425-844-1987
May 7, 2004
Gough Development, Inc. �
c/o Davis Consulting, Inc.
27013 Pacific Highway South
' PMB#353
Des Moines, Washington 98198
Geotechnical Engineering Report
Sunset Boulevard Plat
Renton,Washington
CG File No. 1628
Dear 1�Ir. Davis:
INTRODUCTION
This report presents the results of our geotechnical engineering investigation at your proposed 33-lot
residential development in Renton, Washington. The site is located at 4821 Sunset Boulevard NE, as
shown on the Vicinity Map in Figure 1.
You have requested that we complete this report to evaluate subsurface conditions and provide
recommendations for site development. For our use in preparing this report, we have been provided with
an electronic site survey,prepared by Anderson Sun-eyors.
PROJECT DESCRIPTION
We understand that the project will include development of 33 residential lots including access roads and
utilities. We have not been provided with cut and fill information on the site. The majority of the site
slopes down to Honey Creek, flowing through the northern portion of the property. Wetlands, delineated
by others, are located on either side of Honey Creek.
SCOPE
The purpose of this study is to explore and characterize the subsurface conditions and provide
recommendations for site development. Specifically, our scope of services for this report includes the
follo���in�:
Geotechnical Engineering Report �
Sunset Boulevard I
May 7, 2004 I
CG File No. 1628 I
Page 2 �
1. Review available geologic maps for the site area.
2. Explore the subsurface soil and ground water conditions with backhoe-excavated test pits.
3. Provide recommendations for site preparation and grading.
4. Provide recommendations for foundation support.
5. Provide recommendations for minimizing disturbance to creek during construction.
' 6. Prepare a geotechnical report summarizing our observations,conclusions and
recommendations.
SITE CONDITIONS
Surface Conditions
The irregularly-shaped project site has a maximum dimension of 601 feet in the north to south direction
and 330 feet in the east to west direction. The site is bordered by Sunset Boulevard to the north,
multifamily residential property to the west, and wooded land to the south and east. A layout of the Site
Plan is shown in Figure 2. From the southern end of the property, the ground surface is level, then slopes
down at an approximately 30 degree angle,then gently gades downward to the creek.
An existing residence is located toward the south end of the site, and is to be demolished for development.
T'he site is littered with scattered debris and machinery. A portion of the upper, southern half of the site is
covered with wood chips that extend out over the top of the steeply-sloping areas.
_ Geology
Most of the Puget Sound Region was affected by past intrusion of continental glaciation. The last period
of glaciarion, the Vashon Stade of the Fraser Glaciation,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
typical glacial sequence includes recessional outwash sand underlain by glacial till.
Our site explorations encountered glacial till. Glacial till is an unsorted mixture of sand, silt, and gravel I
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 continental glaciers. The till exhibits both high strength
and low permeabiliry.
Cornerstone Geotechnical, Inc.
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Geotechnical Engineering Report
Sunset Boulevard
May 7, 2004
GG File No. 1628
Page 3
Explorations
Subsurface conditions were explored at the site on April 6, 2004, by excavating five test pits with a
backhoe. The explorations were located in the field by a geologist from this firm who also examined the
soils and geologic conditions encountered, and maintained logs of the test pits. The test pits were
excavated to depths of 7.0 to 11.0 feet below the ground surface. 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 our explorations is included below. For a more
detailed description of the soils encountered,review the test pit logs in Figure 4 and 5.
Our explorations typically encountered fill material that ranged from 1.0 to 9.0 feet in thiclrness. Test Pit
4 did not reach native material, meeting refusal on large concrete fragments. Test Pit 5, located
immediately down slope of Test Pit 4, encountered fill for 4S feet overlying native silty sand with gravel.
The fill consists of organic matter, wood scraps, metal,plastic,bottles, bricks, shingles, grass cuttings and
concrete. This fill was encountered in all of our explorations, except Test Pit 2, located in the
southwestern corner of the property. The topsoil at Test Pit 2 consisted of loosey dark brown silty sand
with organics, gravel and roots,and the underlying material consisted of inedium dense to very dense silty
sands, consistent with glacial till.
Hydrologic Conditions
Ground water seepage was encountered in most of our explorations. We consider this water to be
perched. We also encountered rust-staining to various depths in most of our explorations. This mottled
zone is 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 below this mottled zone is considered
poorly draining. During the wetter times of the year, we expect perched water conditions will occur as
pockets of water on top of the till layer. 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. The wetland areas are considered depressions in the till surface �I
where perched water and surface water runoff can accumulate.
Cornerstone Geotechnical, Inc. 'I
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Geotechnical Engineering Report I',
Sunset Boulevard '
May 7,2004 ,
CG File No. 1628 ',
Page 4 '
Erosion Hazard �'
The erosion hazard criteria used for determination of affected areas include soil type, slope gradient,
vegetation cover, and ground water conditions. The erosion potential is related to vegetative cover and
the specific surface soil types (group classification), which are related to the underlying geologic units.
Over the majority of the site we consider the erosion hazard to be slight with vegetative cover in place
, and moderate when stripped of vegetation. Best management practices (BMPs) and applicable codes
should be followed during site grading to limit potential for erosion. We do not expect this site will
require unusual or extreme erosion management methods.
Landslide Hazard
The site does not show evidence of having significant slope stability problems. T'he teirain within the site
is gently to moderately sloping, with no steep slopes other than existing fill embankments. Based on our
explorations, it is our opinion that the core of the hiilside is composed of dense glacial soils, and the
subject site is underlain by dense to very dense glacial till. The vertically-oriented trees at the site, taken
�vith the age of the existing residence,indicate that the site has performed well for many years. We would
expect that any failures associated with the slope to be a small, shallow slough-type movement. If these
- failures did occur, we expect that they would not pose a significant risk to the planned development.
�
CONCLUSIONS AND RECOMMENDATIONS
General
It is our opinion that the site is compatible with the planned development. T'he underlying medium dense
, to very dense glacial deposits are capable of supporting the planned structures and pavements. We ,
recommend that the foundations for the sh-uctures extend through any topsoil, artificial fill, loose, or '
disturbed soils, and bear on the underlying medium dense to very dense, native glacial soils, or on I,
structural fill extending to these soils. II
The soils likely to be exposed during construction, are extremely moisture sensitive and will disturb �
easily when wet or during wet conditions. We recommend that construction take place during the drier
summer months, if possible. If construction takes place during the wet season, additional expenses and
delays should be expected due to the wet conditions. Addirional expenses could include additional depth
of site stripping, export of on-site soil, the import of clean granular soil for fill, and the need to place a
blanket of rock spalls in the access roads and paved areas prior to placing structural fill.
Cornerstone Geotechnical, Inc.
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Geotechnical Engineering Report
Sunset Boulevard
May 7, 2004
CG File No. 1628
Page 5
Site Preparations and Grading
The first step of site preparation should be to strip the extensive amount of existing fill, topsoil, or loose
soils on the southern portion of the property. The fill is up to approximately 8 to 9 feet thick, possibly
thicker, and extends across much of the southern portion of the property. This material should be
excavated and removed from the site to expose medium dense to very dense native soils. 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
" construction could include extra excavation and use of imported fill or rock spalls. During wet weather,
alternarive site preparation methods may be necessary. T'hese methods may include utilizing a smooth-
bucket trackhoe to complete site stripping and diverting construction traffic around prepared subgrades.
Disturbance to the prepared 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 helpful in reducing
grading costs during the wet season. These methods can be evaluated at the time of construction.
Creek Disturbance
The planned buffer 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 disturbed areas. Stockpiles
that will be exposed for extended periods of time in the wet season should be covered with plastic. Storm
water should be routed to an appropriate temporary storm water handling 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 monitored daily. If discharge
water is found to concentrate or have silt content exceeding regulatory limits, corrections or
improvements to the storm water system should be implemented immediately.
Cornerstone Geotechnical, Inc.
Geotechnical Engineering Report
Sunset Boulevard
May 7,2004
CG File No. 1628
Page 6
Structural Fill
General: All fill placed beneath buildings, pavements or other settlement sensitive features should be
placed as structural fill. Structural fill,by definition, is placed in accordance with prescribed methods and
standards, and is monitored by an experienced geotechnical professional ar soils technician. Field-
monitaring procedures would include the performance of a representative number of in-place density tests
' to document the attainment of the desired degree of relative compaction.
�'Iaterials: Imported structural fill should consist of a good quality, free-draining gc-anular soil, free of
organics and other deleterious material, and be well graded to a maximum size of about 3 inches.
Imported, all-weather structural fill should contain no more than 5 percent fines(soil finer than a Standard
U.S. No. 200 sieve),based on that fraction passing the U.S. 3/4-inch sieve.
The on-site native soil can be used as structural fill, but its use will be dependent on moisture content
control. 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 and/or 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. The existing fill
contains abundant organic material and debris and, in our opinion, should not be considered for use as
structural fill. This can be evaluated during construction.
Fill Placement: Following subgrade preparation, placement of the structural fill may proceed. Fill
should be placed in 8- to 10-inch-thick uniform lifts, 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 least 95
percent of its maximum dry density. Maximum dry density, in this report, refers to that 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 optimum so that a
', readily compactable condition exists. It may be necessary to overexcavate and remove wet surficial soils ,i
in cases where drying to a compactable condition is not feasible. All compaction should be accomplished �
, by equipment of a type and size sufficient to attain the desired degree of compaction.
, Cornerstone Geotechnical, Inc.
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Geotechnical Engineering Report
Sunset Boulevard ,
May 7, 2004 '
CG File No. 1628 '
Page 7
Temporary and Permanent Slopes
Temporary cut slope stability is a function of many factors, such as the type and consistency of soils,
depth of the cut, surcharge loads adjacent to the excavation, length of time a cut remains open, and the
presence of surface or ground water. It is exceedingly difficult under these variable conditions to estimate
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
', temparary cuts in the near-surface weathered soils be no greater than 1 Horizontal to 1 Vertical (1H:1V).
Cuts in the dense to very dense soils may stand at a 1H:1V 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 plastic sheeting and diverting surface runoff away from the top of cut slopes. We do not
recommend vertical slopes for cuts deeper than 4 feet, if warker access is necessary. We recommend that
cut slope heights and inclinations conform to local and WISHA/OSHA standards.
Final slope inclinations for structural fill and the cuts in the native soils should be no steeper than 2H:1 V.
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 "trackrolled" into place. They would not meet the compaction
specification of structural fill. Final slopes should be vegetated and covered with straw or jute netting.
The vegetation should be maintained until it is established. �
Foundations '
Conventional, 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 I
overpoured with extra concrete.
Cornerstone Geotechnical, Inc.
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Geotechnical Engineering Report
Sunset Boulevard
May 7, 2004
CG File No. 1628
Page 8
Footings should extend at least 18 inches below- the lowest adjacent finished ground surface for frost
protection and bearing capacity considerations. Minimum foundation widths of 12 and 18 inches should
be used for continuous and isolated spread footings, respectively. Standing water should not be allowed
to accumulate in footing trenches. All loose or disturbed soil should be removed from the foundation
excavation prior to placing concrete.
' For foundarions constructed as outlined above, we recommend an allow�able design bearing pressure of
2,000 pounds per square foot (ps fl 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 40 feet. Higher soil
bearing values may be appropriate for footings founded on unweathered till, and with wider footings.
These higher values can be determined after a review of a specific design.
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 foundarion. 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 triangular equivalent fluid pressure distribution. We
recommend that an equivalent fluid density of 200 pounds per cubic foot (pc fl 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 0.40 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 resistance pressure to account
for required movements to generate these pressures. The friction coefficient does not include a factor of
safety.
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 fill
extending to these soils. Where moisture control is a concern,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 plastic sheeting, should be placed over the capillary break.
Cornerstone Geotechnical, Inc.
Geotechnical Engineering Report
Sunset Boulevard
May 7, 2004
CG File No. 1628
Page 9
Drainage
We recommend that runoff from impervious surfaces, such as roofs, drive«ay and access road�vays, be
collected and routed to an appropriate storm water discharge system. Final 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 lines, and be discharged into a storm drain system.
We recommend that footing drains be used around all of the structures where moisture control is
important. The underlying till will pond water that accumulates in the crawl space. It is good practice to
use footing drains installed at least 1 foot below planned finished floor slab or crawl space elevation to
provide drainage for the crawl space. At a minimum, the crawl space should be sloped to drain to an
outlet tied to the drainage system. If drains are omitted around slab-on-grade floors where moisture
control is important, the slab should be a minimum of 1 foot above surrounding grades.
Where used, footing drains should consist of 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
appropriate collection and discharge point. Crawl spaces should 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 from 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 de«ratering will not be needed to install utilities. Anticipated
ground water is expected to be handled with pumps in the trenches. 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 pockets. We do not expect significant volumes of water in these excavarions.
The soils likely to be exposed in utility trenches after site stripping are considered highly moisture
sensitive. We recommend that they be considered for trench backfill 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 the wet season, 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.
Cornerstone Geotechnical, Inc.
Geotechnical Engineering Report
Sunset Boulevard
May 7, 2004
CG File No. 1628
Page 10
Rockeries
Rockeries may be used to face stable cuts in the dense or glacial native soils. We recommend that ���e
review planned rockeries exceeding 6 feet in height without a backslope, or 4 feet in height with a
backslope and/or retaining fill. We recommend that rockeries be constructed to Associated Rockery
Contractors (ARC) guidelines and appropriate local standards. Rockeries retaining fill in excess of 4 feet
, should be specifically designed, and may require the use of soil reinforcing. Design of fill rockeries,
which may require geotextile reinforcement, is outside the scope of this report.
Pavement
T'he performance of roadway pavement is critically 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 and Grading subsection of this report. Prior to placing base material, the subgrade
soils should be compacted to a non-yielding state with a vibratory roller compactor and then proof-rolled
with a piece of heavy construction equipment, such as a fully-loaded dump truck. Any areas with
excessive weaving or flexing should be overexcavated and recompacted or replaced with a structural fill
or crushed 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 are consistent with those indicated by the explorations, and to provide
recommendations for design changes, should the conditions revealed during the work differ from those
anticipated. As part of our services, we would also evaluate whether or not earthwark and foundation
installation activities comply with contract plans and specifications.
USE OF THIS REPORT
We have prepared this report for Gough Development, Inc., 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 scope of our work does not include services related to construction safety precautions, and our
recommendations are not intended to direct the contractors' methods, techniques, sequences or
Cornerstone Geotechnical, Inc.
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Geotechnical Engineering Report '
Sunset Boulevard II
May 7, 2004 '',
CG File No. 1628 I
Page 11 I
procedures, except as specifically 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 report was prepared. No other conditions, expressed or implied, should be understood.
We appreciate the opportunity 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.
i
Kris Addis
Staff Geologist
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Cornerstone Geotechnical, Inc.
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01995 Thomas Bros. Maps _ ,
Cornerstone Phone:(425)844-1977 Sunset Boulevard
�1 Fax:(425)844-1987
.�:�Y= Geotechnical� IIIC. FileNumber 1628 Figure ,)
17625-130th Ave NE, C-102 •Woodinvilie, WA• 98072
Site Plan
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� // '�, � ; . � � , �- � � � � g ;� Number and Approximate
�
��'� ! � �'; ,, t �`4 � � ' + � . � - �n n ` ' Location of Test Pit
; . . • ! . � �` � ' i _ � =
� Approximate areas with significant fills o so �Zo
Scale 1"=60'
Cornerstone Phone:{425)844-1977 Sunset Boulevard
Fax:(425)844-1987
� Reference: Site Plan based on scanned version ofelectronic site survey, provided byAnderson Surveyors � ,. Geotechnical� �nC. File Number Figure
`�� 17625-130th Ave NE,C-102 •Woodinville,WA• 98072 1 fi28 2
Unified Soil Classification System II
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 NO.4 GRAVEL
siEv� WITH FINES GM SILTYGRAVEL
GC CLAYEY GRAVEL
MORE THAN 50%
RETAINED ON SAND CLEAN SAND SW y�LL-GRADED SAND,FINE TO COARSE SAND
' number 200 SIEVE
SP POORLY-GRADED SAND
MORE THAN 50°k OF
COARSE FRACTION SAND
PASSES NO.4 SIEVE �TH FINES SM SILTY SAND
SC CLAYEY SAND
SILTAND CLAY INORGANIC ML SILT
FINE-
GRAINED LIQUID LIMIT CL CLAY
LESS THAN 50%
SOILS ORGANIC OL ORGANIC SILT, ORGANIC CLAY
MORE THAN 50% SILTAND CLAY INORGANIC
PASSES NO.200 SIEV MH SILT OF HIGH PLASTICITY,ELASTIC SILT '
LIQUID LIMIT CH CLAY OF HIGH PLASTICITY,FAT CLAY
50°�OR MORE
ORGANIC OH ORGANIC CiAY,ORGANIC SILT
HIGHLY ORGANIC SOILS pT PEAT
NOTES:
SOIL MOISTURE MODIFIERS
1) Field classification is based on Dry-Absence of moisture, dusty, 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
tests is based on ASTM D 2487-83. Wet-Visible free water or saturated, ',
3) Descriptions of soil density or usually soil is obtained from
consistency are based on below water table
interpretation of blowcount data,
visual appearance of soils, and/or
test data. �
_ Unified Soil Classification S stem '
Cornerstone Phone:(425)844 1977 y I
�� Geotechnical, Inc. Fax:(425)844-1987 �
Fi ure 3 '
17625-130th Ave NE,C-102 •Woodinville,WA• 98072 g
LOG OF EXPLORATION
DEPTH USC SOIL DESCRIPTION II
TEST PIT ONE
0.0-1.0 ASSORTED DEBRIS(WOOD SCRAPS,SHINGLES,CONCRETE) F( ILL) I
1.0-2.5 ML DARK BROWN SANDY SILT WITH ORGANIC MATTER AND ROOTS (SOFT, MOIST)
(TOPSOI L)
2.5-6.0 SM/ML RUST-STAINED GRAY-BROWN SANDY SILT WITH OCCASIONAL GRAVEL
INTERBEDDED WITH BLUE GRAY SILTY SAND WITH TRACE ORGANICS (LOOSE TO
MEDIUM DENSE/SOFT TO MEDIUM STIFF,MOIST TO WET)
6.0-10.0 SM/ML RUST-STAINED BLUE GRAY SILTY SAND INTERBEDDED WITH RUST-STAINED GRAY
SANDY SILT(MEDIUM DENSE/STIFF,WET)
� 10.0-11.0 SM BROWN-GRAY SILTY SAND WITH GRAVEL(VERY DENSE,MOIST)(TILL)
SAMPLES WERE COLLECTED AT 1.0,3.0, 10.0 AND 11.0 FEET
GROUND WATER SEEPAGE WAS ENCOUNTERED AT 4.0 FEET
TEST PIT CAVING WAS ENCOUNTERED FROM 4.0 TO 5.0 FEET
TEST PIT WAS COMPLETED AT 11.0 FEET ON 04/06/04
TEST PIT TWO
0.0-1.5 SM DARK BROWN SILTY SAND WITH ORGANICS, GRAVEL AND ROOTS(LOOSE, MOIST)
(TOPSOIL)
1.5-3.0 SM RED-BROWN SILTY SAND WITH GRAVEL AND ROOTS (LOOSE TO MEDIUM DENSE,
MOIST)(WEATHERED TILL)
3.0-5.0 SM BROWN-GRAY SILTY FINE TO MEDIUM SAND WITH GRAVEL AND OCCASIONAL
COBBLES(DENSE,WET)
5.0-6.0 SM/ML RUST-STAINED GRAY SILTY FINE SAND WITH SILT SEAMS (DENSE TO VERY
DENSE,MOIST)
6.0-7.0 SM GRAY BROWN SILTY SAND WITH GRAVEL(VERY DENSE, MOIST)(TILL)
SAMPLES WERE COLLECTED AT 3.0,3.5 AND 6.0 FEET
SLIGHT GROUND WATER SEEPAGE WAS ENCOUNTERED AT 6.0 FEET
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 7.0 FEET ON 04/06/04
TEST PIT THREE
0.0-8.0 SM DARK BLUE-GRAY SILTY SAND WITH PURPLE-COLORED ORGANICS, CONCRETE,
PLASTIC,BRICK, ROOTS,AND GRASS CUTTINGS(LOOSE,WET)(FILL)
8.0-11.0 SM/ML RUST-STAINED RED-BROWN SANDY SILT WITH ROOTS INTERBEDDED WITH RED
BROWN SILTY FINE SAND(MEDIUM DENSE/STIFF,MOIST)
SAMPLES WERE COLLECTED AT 4.0 AND 11.0 FEET
GROUND WATER SEEPAGE WAS ENCOUNTERED AT 8.0 FEET
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 11.0 FEET ON 04/06/04 ',
TEST PIT FOUR '�
0.0-9.0 SM GRAY SILTY SAND WITH GRAVEL, BRICKS, GRASS CUTTINGS, PLASTIC BOTTLES, I
PLASTIC BAGS, WOOD, OCCASSIONAL COBBLES AND LARGE BLOCKS OF I
CONCRETE(1 FT X 3 FT X 3 FT)(LOOSE, MOIST) FLILL) I
SAMPLE WAS COLLECTED AT 8.0 FEET �I
GROUND WATER SEEPAGE WAS NOT ENCOUNTERED I,
TEST PIT CAVING WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 9.0 FEET ON 04/06/04
CORNERSTONE GEOTECHNICAL, INC.
FILE NO 1628
FIGURE 4
�
LOG OF EXPLORATION
DEPTH USC SOIL DESCRIPTION
� TEST PIT FIVE
0.0-2.0 SM BROWN SILTY SAND WITH GRAVEL, METAL, WOOD, LARGE CONCRETE BLOCKS,
PLASTIC,ROOTS,BRICK,ASPHALT(LOOSE, MOIST) F( ILL)
- 2.0-4.5 ML BROWN SANDY SILT WITH GRAVEL, A LARGE CEDAR STUMP AND ORGANIC
MATTER(LOOSE, MOIST) F( ILL)
, 4.5-7.5 SM RUST-STAINED BLUE GRAY SILTY SAND WITH GRAVEL AND ORGANICS (MEDIUM
DENSE,MOIST TO WET)
7.5- 8.0 SM BROWN GRAY SILTY SAND WITH GRAVEL(DENSE TO VERY DENSE, MOIST)(TILL)
, NO SAMPLES WERE COLLECTED
GROUND WATER SEEPAGE WAS ENCOUNTERED AT 6.0 FEET
TEST PIT CAVfNG WAS NOT ENCOUNTERED
TEST PIT WAS COMPLETED AT 8.0 FEET ON 04/06/04
CORNERSTONE GEOTECHNICAL, INC.
FILE NO 1628
FIGURE 5
� _--