HomeMy WebLinkAboutBPW03170 GEOTECHNICAL INVESTIGATION
SOUTH INTERCEPTOR PARALLEL: PHASE H
OAKESDALE AVENUE S.W.
RENTON, WASHINGTON
HWA Project No. 93093
September 19, 1994
Prepared for:
GARRY STRUTHERS ASSOCIATES, INC.
HIM
flONG WEST
Er AS SOCI ATE S, INC.
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flONGWEST
& ASSOCIATES, INC.
Geotechnical Engineering
September 19, 1994 Hydrogeology
HWA Project No. 93093 Geoenvi ron mental Services
Testing &Inspection
Garry Struthers Associates, Inc.
2955 80th Avenue S.E., Suite 102
Mercer Island, Washington 98040
Attention: Mr. Gary Thompson, P.E.
Subject: GEOTECHNICAL INVESTIGATION
South Interceptor Parallel: Phase II
Oakesdale Avenue S.W.
Renton, Washington
Dear Mr. Thompson:
In accordance with your request, Hong West & Associates, Inc. completed a geotechnical
investigation for Phase II of the Metro South Interceptor Parallel, located along Oakesdale
Avenue S.W., between about S.W. 31st Street and S.W. 43rd Street in Renton,
Washington. The results of our study are presented in the accompanying report.
We appreciate the opportunity to provide geotechnical services on this interesting and
challenging project, and look forward to providing further services during design review
and construction. Should you have any questions or comments, or if we may be of further
service, please do not hesitate to call.
Sincerely,
HONG WEST& ASSOCIATES, INC. �, 9
28265
NALC�—
ExP1AES
Steven R. Wright Scott L. Hardman, P.E.
Geotechnical Engineer Senior Geotechnical Engineer
SRW:SLH(93093R.doc)
19730-64th Avenue West
Lynnwood,WA 98036-5904
Tel. 206-774-0106
Fax. 206-775-7506
TABLE OF CONTENTS
Page
1.0 INTRODUCTION..............................................................................1
1.1 PROJECT BACKGROUND .......................................................1
1.2 PROJECT DESCRIPTION.........................................................2
1.3 AUTHORIZATION AND SCOPE OF WORK.................................2
2.0 FIELD AND LABORATORY INVESTIGATIONS ......................................4
2.1 FIELD EXPLORATION ...........................................................4
2.2 LABORATORY TESTING ........................................................4
3.0 SITE CONDITIONS ...........................................................................5
3.1 SURFACE CONDITIONS.........................................................5
3.2 GENERAL GEOLOGIC CONDITIONS ........................................5
3.3 SUBSURFACE CONDITIONS ...................................................6
3.3.1 Soils ........................................................................6
3.3.2 Groundwater ..............................................................8
4.0 CONSTRUCTION OF EXISTING INTERCEPTORS....................................9
4.1 EXISTING 72-INCH DIAMETER INTERCEPTOR ..........................9
4.2 EXISTING 108-INCH DIAMETER INTERCEPTOR....................... 10
5.0 CONCLUSIONS AND RECOMMENDATIONS ....................................... 11
5.1 EARTHQUAKE ENGINEERING .............................................. 11
5.1.1 Site Seismicity .......................................................... 11
5.1.2 Seismic Design Parameters ........................................... 12
5.1.3 Soil Liquefaction Potential............................................ 13
5.2 DEWATERING.................................................................... 14
5.2.1 Dewatering System Alternatives ..................................... 14
5.2.2 Impacts of Dewatering................................................. 16
5.2.3 Disposal of Dewatering Effluent ..................................... 17
5.3 EXCAVATION AND SHORING............................................... 17
5.3.1 Open Cut Excavations ................................................. 17
5.3.2 Laterally Supported Excavations ..................................... 18
5.4 RAILROAD TRACK UNDER-CROSSING................................... 19
5.4.1 Design Considerations for Jacked Pipe Installations .............. 19
5.4.2 Construction Considerations for Jacked Pipe Installations........ 20
5.5 SPRINGBROOK CREEK UNDER-CROSSING.............................. 21
5.5.1 Temporary Support for Springbrook Creek CMP's ............... 21
5.5.2 Jacking Circular Pipes under Springbrook Creek.................. 22
5.5.3 Jacking a Rectangular Structure under Springbrook Creek....... 22
5.6 PIPE SUPPORT AND TRENCH BACKFILL ............................... 22
5.6.1 Pipe Bedding ............................................................ 23
5.6.2 Trench Backfill ......................................................... 24
5.7 EXTERNAL LOADS IMPOSED ON BURIED PIPE....................... 25
5.8 BURIED STRUCTURES......................................................... 26
5.9 PIPE SETTLEMENT............................................................. 26
6.0 UNCERTAINTY AND LIMITATIONS.................................................. 27
7.0 REFERENCES................................................................................. 28
TABLE OF CONTENTS (continued)
TABLES
Table 1. Summary of Groundwater Depths/Elevations in HWA Explorations.................8
Table 2. Seismic Design Parameters.............................................................................12
Table 3. Estimated Externally Imposed Loads on Buried 108-inch Diameter
RidgePipe.....................................................................................................25
Table 4. Unit Weights for Backfill Soils.......................................................................26
FIGURES (Following Text)
Figure 1. Vicinity Map
Figure 2. - 4. Site and Exploration Plans
Figure 5. - 7. Generalized Geologic Cross-Sections
Figure 8. Summary of Potentially Liquefiable Zones
Figure 9. Lateral Earth Pressures for Cantilevered and Multiple Braced Excavations
Figure 10. Compaction Criteria for Trench Backfill
APPENDICES
Appendix A: Field Exploration
Figure A-L Legend of Terms Used on Exploration Soil Logs
Figure A-2. Legend of Symbols Used on Exploration Soil Logs
Figures A-3. -A-10. Boring Logs BH-1 to BH-4
Figure A-ll. Cone Penetrometer Test (CPT) Sounding Legend
Figures A-12. -A-]7. CPT Sounding Logs CPT-1 to CPT-6
Appendix B: Laboratory Testing
Table B-1. Summary of Atterberg Limits Test Results
Table B-2. Percent Passing U.S. No. 200 Sieve Test Results
Figures B-1. -B-4. Grain Size Distribution Curves
Figures B-5. -B-6. Consolidation Test Plots
Figures B-7. -B-10. Unconfined Compression Test Plots
93093R.doc ii HONG WEST& ASSOCIATES, INc.
GEOTECHNICAL INVESTIGATION
SOUTH INTERCEPTOR PARALLEL: PHASE II
OAKESDALE AVENUE S.W.
RENTON, WASHINGTON
1.0 INTRODUCTION
Hong West & Associates, Inc. (HWA) performed a geotechnical investigation for
Phase II of the Metro South Interceptor Parallel project, located along Oakesdale
Avenue S.W., between about S.W. 31st Street and S.W. 43rd Street in Renton,
Washington, as shown on the Vicinity Map, Figure 1. The purpose of the study is to
explore and evaluate the surface and subsurface conditions along the project alignment,
and based on the conditions encountered, provide recommendations pertaining to the
geotechnical aspects of the proposed improvements.
Based on the results of our study, geotechnical aspects of the proposed improvements
are considered feasible, provided the recommendations presented in this report are
implemented during design and construction.
1.1 PROJECT BACKGROUND
In the late 1960's, Metro's South Interceptor Sewer was constructed as the first phase
of the planned construction of parallel pipelines. The existing sewer, which consists of
1,100 feet of 90-inch diameter pipe, followed by 11,000 feet of 72-inch diameter
concrete pipe, intercepts wastewater flows from the area south of the East Division
Reclamation Plant at Renton.
An assessment of the hydraulic capacity restrictions on the existing interceptor system
was performed by others and the South Interceptor was identified as reaching hydraulic
capacity by 1995. It is estimated that the existing South Interceptor would flood
between the south Renton Trunk and the Kent Cross Valley Interceptor during a five
year storm event by 1995, unless additional capacity is added.
Based on the results of the hydraulic analysis, it was recommended by others that a
portion of the planned South Interceptor Parallel be constructed from the terminus of
the existing South Interceptor at S.W. 16th Street to S.W. 43rd Street by 1995. In
order to facilitate coordination with development activities by the Boeing Company at
its Longacres property, the design and construction of the South Interceptor Parallel
was divided in two phases. Phase I of the project, which was recently completed,
includes the northern 5,000 feet of the recommended Interceptor, while Phase II
includes the southern 4,200 feet. This report presents results of our on-site
investigation and geotechnical evaluations related to the design and construction of
Phase II of the South Interceptor Parallel.
September 19, 1994
HWA Project No. 93093
1.2 PROJECT DESCRIPTION
We understand that Phase II of this project involves the design and construction of an
interconnection structure at the southern terminus of Phase I. The interconnection
structure will be designed to tie the proposed interceptor to the southern terminus of
Phase I and the existing 72-inch diameter South Interceptor. In addition, the project
will include the design and construction of a new 108-inch diameter interceptor
approximately 4,200 feet in length, from the interconnection structure to S.W. 43rd,
along Oakesdale Avenue S.W., as shown on the Site and Exploration Plans, Figures 2
through 4. At the southern end of the project, a crossing structure at the intersection
of Oakesdale Avenue S.W. and S.W. 43rd Street will be designed and constructed.
The reinforced concrete structure will incorporate the proposed interceptor, the 36-inch
diameter South Renton trunk line, and the existing 72-inch diameter South Interceptor.
At this stage in project planning, it is anticipated that the proposed interceptor will
consist of a reinforced, pre-cast concrete pipe. It is anticipated that the proposed
interceptor will maintain an invert elevation that is approximately equivalent to that of
the existing 72-inch diameter interceptor, which ranges between about elevation 97 and
99 feet. Consequently the required excavation depths to the invert elevation of the
proposed interceptor will range between about 18 and 20 feet below the existing ground
surface.
At about Stations 78+60 and 79+50 the proposed interceptor will cross under two
separate Burlington Northern Railroad tracks. At these crossings, we understand the
pipe will be installed using either open cut, jacking, or tunneling techniques. At about
Station 82+75, the proposed interceptor will cross under Springbrook Creek, which is
presently transmitted under Oakesdale Avenue S.W. by four corrugated metal pipes
(CMP's). Due to the vertical alignment of the proposed interceptor, we understand
that there is not sufficient space between the top of the interceptor and the bottom of
the CMP's to install the 108-inch diameter pipe. As a result a low head structure with
transitions to the pipe on either side of the crossing will be required.
1.3 AUTHORIZATION AND SCOPE OF WORK
A proposal for the performance of this geotechnical investigation was submitted by
HWA to Garry Struthers Associates, Inc. (GSA) on August 16, 1993. The proposed
scope of services was subsequently authorized by Mr. Garry Struthers of GSA. The
scope of work for this project was described in our proposal letter and included the
following tasks:
1) Collect and review readily-available geotechnical and geologic
data for the project area;
93093R.DOC 2 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
2) Coordinate the field activities with the project team and obtain
utility clearances;
3) Plan and conduct a subsurface investigation along the proposed
alignment of the project, to obtain information relative to soil and
geologic conditions at the site;
4) Conduct laboratory testing to determine selected geotechnical
engineering properties of the on-site soils;
5) Perform engineering analyses and evaluation of data derived from
the subsurface investigation and laboratory testing program, with
respect to the proposed project;
6) Provide project management and participate in meetings related
to the geotechnical study, and;
7) Prepare this report containing the results of our geotechnical
investigation, including descriptions of surface and subsurface
conditions, a site plan showing borehole locations and other
pertinent features, geologic profiles, descriptions and results of
engineering analyses and laboratory testing performed, and
geotechnical engineering recommendations pertaining to the
following items:
a) Pipe bedding and foundation support;
b) Utility trench backfill;
c) Earth pressures on buried pipes;
d) Excavation shoring and dewatering;
e) Culvert and railroad under-crossings; and
f) General site excavation characteristics, earthwork
recommendations, and other construction considerations.
Environmental sampling and testing of the soil or groundwater to evaluate the potential
for the presence of hazardous materials along the proposed project alignment were not
within the scope of services authorized or performed.
93093R.DOC 3 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
2.0 FIELD AND LABORATORY INVESTIGATIONS
2.1 FIELD EXPLORATION
HWA personnel conducted a site reconnaissance and subsurface exploration program
between December 6 and 8, 1993 to characterize the surface and subsurface conditions
along the project alignment. The subsurface exploration consisted of drilling and
sampling four mud rotary borings (BH-1 through BH-4) to depths ranging from about
511/2 to 611/2 feet below the existing ground surface, and performance of six cone
penetrometer test (CPT) soundings (CPT-1 through CPT-6) to depths ranging from
about 34 to 45 feet. HWA personnel obtained disturbed Standard Penetration Test
(SPT) samples and relatively undisturbed Shelby tube samples at selected intervals in
each of the borings. In addition, we installed standpipe piezometers in each of the
boreholes. Approximate locations of the explorations performed are shown on the Site
and Exploration Plans, Figures 2 through 4. These figures also indicate approximate
locations of several selected exploratory borings conducted by a previous investigator j
(Metropolitan Engineers, 1967).
Field exploration methods are described and logs of the borings and CPT soundings are
contained in Appendix A. The borehole and CPT locations were established in the
field by GSA's survey crew and plotted on the project base map. The locations of the
boreholes and CPT soundings should be considered approximate and only as accurate
as the locating method implies.
2.2 LABORATORY TESTING
Laboratory tests were conducted on selected soil samples to characterize certain
engineering properties of the on-site soils. Laboratory tests included determination of
moisture content, grain-size distribution, and Atterberg Limits. In addition, four
relatively undisturbed samples were selected for consolidation and unconfined
compressive strength testing. Testing was conducted in general accordance with
appropriate American Society for Testing and Materials (ASTM) standards. The test
results, along with a discussion of laboratory test methodology, are presented in
Appendix B, or displayed where appropriate on the logs in Appendix A.
93093R.DOC 4 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
3.0 SITE CONDITIONS
The following section describes the general surface and subsurface conditions of the
project alignment. Interpretations of the site conditions are based on our site
reconnaissance, subsurface exploration, and available geologic and topographic maps.
3.1 SURFACE CONDITIONS
The project alignment, which follows Oakesdale Avenue S.W., is characterized by the
relatively level topography of the Duwamish Valley, with elevations ranging between
about 116 and 118 feet. Oakesdale Avenue S.W. is an existing five-lane, paved road
with curbs and gutters, which extends north-south through a mixed neighborhood of
commercial/industrial developments and undeveloped properties. In the vicinity of
Springbrook Creek, the adjoining properties exhibited vegetation indicative of wetland
areas. Between approximate Stations 72+00 and 86+00, we understand Shapiro and
Associates, Inc. has mapped wetlands in the vicinity of the project alignment.
Springbrook Creek flows generally from south to north in the vicinity of the project
alignment. Along the southern portion of the project alignment, Springbrook Creek,
which is located to the west of the alignment, flows towards the northeast. At
approximately Station 82+75, Springbrook Creek intersects the project alignment. At
this location, the creek is transmitted under Oakesdale Avenue S.W. by four 72-inch
diameter CMP's. North of the culvert crossing, Springbrook Creek parallels the
eastern side of the project alignment for a short distance, before once again flowing to
the northeast and away from the project alignment.
At approximately Station 79+50, the project alignment crosses a set of Burlington
Northern Railroad tracks that we understand is still in use. About 90 feet north of the
above described tracks, another set of railroad tracks cross the project alignment;
however, this set of tracks is no longer in use.
3.2 GENERAL GEOLOGIC CONDITIONS
The project alignment is located east of the Green River which lies within the north-
south trending Duwamish Valley. The Duwamish Valley occupies a glacially carved
trough sculpted by several glacial advances and retreats. The trough has subsequently
been partially filled with several hundred feet of post-glacial sediment consisting almost
entirely of alluvium from the three major rivers in the area; the Cedar, Green, and
White Rivers. Post glacial sediments have subsequently accumulated in the Duwamish
Valley since the retreat of the Vashon Glacier, about 13,000 years ago.
93093R.DOC 5 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
In the vicinity of the project site, near-surface deposits consist chiefly of Overbank
Flood Deposits which are composed of silt, sand, clay, and peat deposited by the Green
and White Rivers, during times when the White River flowed northward in the
Duwamish Valley. According to Mullineaux (1965), the Overbank Flood Deposits are
underlain by White River Sediments which consist of coarse to fine sand with interbeds
of silt and clay. These sediments are underlain at depth by Cedar River Deltaic
Deposits which consist of sand and gravel with interbedded layers of silt, clay, peat,
and at least one layer of volcanic ash.
3.3 SUBSURFACE CONDITIONS
3.3.1 Soils
Based on the soil conditions encountered in our exploratory boreholes, the project
alignment appears to be underlain by a sequence of fill overlying recent alluvial
deposits which extended to the full depth of our borings. The alluvial deposits were
divided into four general stratigraphic sequences, based on soil type, that appeared
somewhat consistent along the project alignment.
Listed below are descriptions of the soil deposits encountered in our exploration in the
order of stratigraphic sequence by which they were deposited, with the youngest units
described first. The generalized depth ranges given are for descriptive purposes only
and may not represent actual conditions at a given location.
• Fill - Fill was encountered at the ground surface in all of our
explorations. The fill, which was encountered directly over the
alluvial deposits, extended to depths ranging from about 11/2 to 3
feet. Typically, the fill consisted of medium dense, silty sand with
gravel. Based on our observations, it appears the fill material was
imported for use as a pavement base for Oakesdale Avenue S.W.
• Overbank Flood Deposits - This unit was encountered in all of our
subsurface explorations directly underlying the fill. The Overbank
Flood Deposits, consisting of very soft to soft, silt to sandy silt,
extended to depths ranging from about 11 to 18 feet below the
ground surface. In boring BH-3, a pocket of very loose, silty sand
with thin interbeds of peat and silt was encountered. Between the
depths of about 71/2 and 12 feet, CPT-6 encountered an interbed
which was interpreted as organic material (peat).
93093R.DOC 6 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
• Upper White River Sediments - A relatively consistent medium
dense, poorly graded sand with silt to silty sand deposit was
encountered in our exploration directly underlying the Overbank
Flood Deposits. Interbeds of soft silt were occasionally encountered
within this deposit. In general, the upper few feet of this deposit
exhibited a looser condition than the lower portion. In addition, the
upper portion of this unit at boring BH-2 and sounding CPT-2
appeared to consist of native material that was used as trench backfill
during construction of the existing 72-inch diameter interceptor.
• Lower White River Sediments - Lower White River Sediments were
encountered directly underlying the Upper White River Sediments at
depths ranging from about 28 to 38 feet below the existing ground
surface. This unit extended to a depth of about 59 feet below the
ground surface at BH-3, and to a depth of about 50 feet at BH-4. In
the remainder of our explorations, the base of this unit was not
penetrated. In general, this unit consists of alternating sequences of
very soft silt and lean clay with interbeds of very soft organic clay
and loose to medium dense, silty sand with varying amounts of
organics and shell fragments. Based on the subsurface explorations,
it appears that this unit becomes thicker towards the southern end of
the project alignment.
• Cedar River Deltaic Deposits - Cedar River Deltaic Deposits were
encountered in borings BH-3 and BH-4, directly underlying the
White River Sediments. The Cedar River Sediments consist of
medium dense to dense, silty sand with trace amounts of organics
and shell fragments. The upper limit of this formation was
penetrated at a depth of about 59 feet below the ground surface at
BH-3, and at a depth of about 50 feet at BH-4. The Cedar River
Sediments extended to the full depth of our explorations where
encountered. South of boring BH-3, this formation was not
encountered within the depths explored.
Generalized Geologic Cross-Sections along the project alignment are shown on Figures
5 through 7. The extrapolation of subsurface conditions between exploration locations
is for illustrative purposes only; actual conditions between explorations may vary
significantly from those shown. The boring and CPT logs in Appendix A provide more
detail relative to soil conditions encountered at specific locations.
93093R.DOC 7 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
Although extensive deposits of peat and organic soils are common in the Duwamish
Valley, significant layers of such materials were not encountered in the HWA
explorations; however, this does not preclude the possible presence of organic soils and
peat in localized areas under the project alignment.
3.3.2 Groundwater
Groundwater was encountered in all of the HWA explorations at depths of about 9 to
10 feet below the ground surface (approximate elevation 107 to 109 feet). Table 1
summarizes the groundwater conditions encountered on the dates noted.
Table 1.
Summary of Groundwater Depths/Elevations in HWA Explorations
Approx. Approx. Approx.
Ground Groundwater Groundwater
Exploration Surface Elev. Depth Elev.
Designation (feet) (feet) (feet)
CPT-1 117.7 9.5(') 108.2
CPT-2 117.2 9.5( ) 107.7
CPT-3 116.5 9( 107.5
CPT-4 118.3 107 3 108.3
CPT-5 117.1 9(F) 108.1
CPT-6 117.3 90 ) 108.3
BH-1 116.8 9.57 107.3
BH-2 117.5 9( ) 108.5
BH-3 117.2 9.5(2) 107.7
BH-4 116.8 9( ) 107.8
(1) Estimated at time of exploration, December 6, 1993.
(2) Measured on December 14, 1993.
The groundwater conditions reported above are for the specific dates and locations
indicated, and therefore, may not be indicative of other times and/or locations.
Furthermore, it is anticipated that groundwater conditions will vary depending on
season, local subsurface conditions, and other factors.
93093R.DOC 8 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
4.0 CONSTRUCTION OF EXISTING INTERCEPTORS
The following section briefly describes the techniques used and the subsurface
conditions encountered during construction of the existing 72- and 108-inch diameter
pipelines located immediately adjacent to or just to the north of the proposed
interceptor.
4.1 EXISTING 72-INCH DIAMETER INTERCEPTOR
Section 2 of the existing 72-inch diameter pipeline, which is located immediately
adjacent and parallel to the proposed alignment for Phase II of the South Interceptor
Parallel, was constructed in the late 1960's by Constructors Pamco. Based on a
telephone interview, as reported by others in a project technical memorandum dated
September 22, 1992, of Mr. John Sheldon, formerly with Constructors Pamco, the
following subsurface conditions were encountered and construction techniques were
used during installation of the existing 72-inch diameter interceptor:
• A crane was used to place the pipe sections, which were installed in
a 20- to 25-foot deep open trench excavated with a dragline. The
sides of the excavation stood at an inclination of about 1H:1V
(horizontal:vertical), but at this slope the side slopes were on the
verge of failure. In order to avoid failure of the trench sidewalls, the
excavated material had to be stockpiled away from the edge of the
trench. For the purpose of safety, a large laying box was used.
• Undesirable soils at the base of the trench were not over-excavated
and the pipe was laid on the excavated subgrade. The pipe was
installed 2 to 4 inches above the intended grade, to account for
settlement once the trench was backfilled.
• The trench excavation encountered large quantities of water, organic
silt, and peat that made construction difficult. The conditions in the
vicinity of S.W. 43rd Street were recalled as being particularly
difficult.
• Construction dewatering was accomplished using deep wells installed
in the underlying sand unit. The wells were installed along only one
side of the trench, on about 75-foot centers. Sand boils in the trench
bottom indicated that in many areas the well spacing was too great.
The extracted water was discharged on the ground about 300 feet to
one side of the excavation. Details regarding pump sizes and
pumping rates were not available.
93093R.DOC 9 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
• The lower one-third to one-half of the pipe was backfilled with
conventional concrete. The remainder of the trench was backfilled
with wet native materials which subsequently settled.
4.2 EXISTING 108-INCH DIAMETER INTERCEPTOR
The recently completed 108-inch diameter pipeline for Phase I of the South Interceptor
Parallel project is located just north of the proposed alignment for Phase II. Based on
several meetings with Tim Clark and Deborah Browne of Metro's Construction
Division, the following construction techniques were employed during installation of
the existing 108-inch diameter interceptor:
• Construction dewatering was performed using 18-inch diameter wells
spaced about 75 feet apart. The wells were located immediately
adjacent to the trench; however, the wells were installed along only
one side of the trench. Each well was equipped with one to two, 5
horsepower, submersible pumps. With 20 to 30 wells in operation,
between 3.3 and 3.5 million gallons of dewatering effluent were
generated per day. The dewatering effluent was routed through a
sediment trap prior to discharge to the existing 72-inch diameter
interceptor.
• In general, the contractor was able to use two stacked laying boxes
for support of the dewatered trench side walls. Tight sheeting was
used only in areas immediately adjacent to wetlands or in areas
where existing utilities needed protection from possible distress due
to loss of ground support.
• In order to help prevent the trench side walls from collapsing against
the sides of the laying boxes, steel sheets were driven between the
trench side walls and the outside edges of the laying boxes. The
steel sheets were embedded several feet below the base of the
excavation and bracing was placed near the top of the sheets to hold
them apart. Using this system, the contractor was able to excavate to
a depth of about 25 feet.
93093R.DOC 10 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
5.0 CONCLUSIONS AND RECOMMENDATIONS
Based on the results of the field exploration, laboratory testing, and engineering
analyses performed, it is our opinion that the proposed South Interceptor Parallel
project is feasible as planned, provided the recommendations of this report are
incorporated in project design and construction. Recommendations are provided below
for design and installation of the proposed interceptor.
5.1 EARTHQUAKE ENGINEERING
The project alignment lies within Seismic Zone 3 as defined by the Uniform Building
Code (UBC, 1988), which is commonly accepted for the design of structures in the
western United States. Seismic Zone 3 includes the Puget Sound region, and represents
an area susceptible to moderately high seismic activity. For comparison, much of
California and southern Alaska are defined as Seismic Zone 4, which is an area of
higher seismic risk. Consequently, moderate levels of earthquake shaking should be
anticipated during the design life of the proposed interceptor. The following sections
discuss seimicity and soil liquefaction potential at the project site.
5.1.1 Site Seismicity
The seismicity of northwest Washington is not as well understood as other areas of
western North America. Reasons for this include (1) relatively recent and sparse
population of the region resulting in incomplete historical records; and (2) deep and
relatively young glacial deposits and dense vegetation which obscure surface expression
of bedrock faults. However, historical records exist of strong earthquakes with local
Modified Mercalli Intensities up to VIII (characterized by structural damage such as
cracked walls and fallen chimneys).
During historical times since the late 1850's, 25 earthquakes of Magnitude (M) 5 and
greater have reportedly occurred in the eastern Puget Sound and north-central Cascades
region. Four events may have exceeded M 6.0. Researchers consider the North
Cascades earthquake of 1872, centered near Lake Chelan, the strongest (M 7.4)
historical earthquake in the region. In addition, earthquakes of M 7.2 occurred in
central Vancouver Island in 1918 and 1946. Other significant historical earthquakes in
the region include a 1949 event near Olympia (M 7.2), and a 1965 event centered
between Seattle and Tacoma (M 6.5).
Potential sources of earthquakes that may be significant to the site include (1) the
Cascadia subduction zone, along which the Juan de Fuca oceanic plate is being thrust
under the North American plate; and (2) shallow crustal faults that may generate
earthquakes in the vicinity of the site (Woodward-Clyde, 1992). In contrast to similar
geologic regimes having subducting plates, such as Alaska or Chile, no earthquakes
93093R.DOC 11 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
have been recorded in the Pacific Northwest from thrust fault type deformation between
plates (interplate earthquakes). However, some seismologist believe that the local
subduction zone has created interplate earthquakes (M A) in the past, and is capable of
future great earthquakes.
It is our opinion that random regional seismicity or shallow crustal earthquakes are
more critical to the proposed improvements than potential ground motions from a
postulated large subduction zone event. This primarily results from the relatively large
distance between the site and potential source areas for subduction zone earthquakes.
Significant ground accelerations could occur at the site in the event of a large
subduction earthquake on the Washington coast. However, the probability of the site
experiencing this magnitude of ground shaking would be quite small, given the large
recurrence interval of postulated subduction zone events.
5.1.2 Seismic Design Parameters
Following review of currently available literature (Grant et al., 1992; Shedlock and
Weaver, 1991; Galster and Laprade, 1991), we selected seismic design parameters for
the site (Table 2). The assumed earthquake magnitude is for a relatively deep-focus
crustal event, and the ground acceleration takes into account the deep alluvium soil
profile at the project site.
Table 2.
Seismic Design Parameters
Seismic Magnitude Peak Site Ground
Event (1V1) Acceleration (% )
100-Year Earthquake 7 0.2
We incorporated the above seismic event in the soil liquefaction analysis (Section
5.1.3), and suggest these values for use in seismic design of the proposed
improvements at the site.
Based on the soils encountered during the exploration program, UBC soil profile type
S3 should be assumed for the project. For use in design, this soil profile type
corresponds to a Site Coefficient of 1.5.
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5.1.3 Soil Liquefaction Potential
General:
When shaken by an earthquake, certain soils lose strength and temporarily behave as a
liquid. This phenomenon is know as soil liquefaction. Seismically induced
liquefaction typically occurs in loose, saturated, sandy materials commonly associated
with recent river, lake, and beach sedimentation. In addition, seismically induced
liquefaction can be associated with areas of loose, saturated fill.
Evaluation of Liquefaction Potential:
We evaluated the soil liquefaction potential of the site soils following procedures
suggested by Seed et al. (1985), utilizing the results of the Standard Penetration Tests
(SPT) performed in the borings, the CPT soundings, and laboratory grain size
characteristics. The analysis was performed assuming the 100-year design event listed
in Table 2.
Research by Seed and Idriss (1982) indicates that for relatively long period, low
frequency seismic waves (as would be induced by the event assumed in the analysis),
the presence of deep, soft soil deposits tend to amplify the seismic waves, causing an
increased maximum acceleration at the ground surface. The site acceleration utilized in
the analysis was adjusted to account for the influence of deep alluvium beneath the site.
For the purpose of the analysis, we assumed groundwater roughly 9 to 10 feet below
the existing ground surface, at approximate elevations of 107 to 109 feet. Materials
classifying as silt (ML) with more than approximately 80 percent fines, and all clay
(CL) deposits were considered non-liquefiable. Furthermore, the Seed et al.
methodology accounts for the effect of increasing fines content in decreasing soil
liquefaction potential.
HWA performed liquefaction potential computations using the computer program
LIQUEFY2 (Blake, 1989). The CPT data were converted to equivalent SPT N-values
based on the work of Jefferies and Davies (1992), and revised based on site-specific in-
situ test data. The semi-empirical method of liquefaction analysis developed by Seed et
al. (1985) is based on a correlation between measured SPT values and field
performance data. The available cyclic strength of the deposit is estimated from the
penetration resistance, and then compared with the cyclic stress ratio induced by the
assumed earthquake event.
Results of the liquefaction potential analyses performed for the individual borings and
CPT sounding are summarized on Figure 8. Depth intervals for soil layers considered
liquefiable under the assumed 100-year seismic event are indicated for each
exploration.
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Effects of Liquefaction:
Potential effects of soil liquefaction include temporary loss of bearing capacity,
liquefaction-induced settlement, and lateral spreading, all of which could result in
significant structural damage to the proposed interceptor. The liquefaction potential
analyses indicate that, for the level of ground shaking considered reasonable for use in
design, the potential for soil liquefaction at the site is moderate to high.
The liquefaction hazard appears restricted primarily to the loose, cohesionless silts and
loose silty sands of the Overbank Flood Deposits described in Section 3.3.1. In
general, the liquefiable soil zones occur predominantly above the proposed pipeline
invert level. In the vicinity of the pipe, these soils will be removed and replaced with
compacted backfill. We identified a few deeper potentially liquefiable zones; however,
as a practical matter, effects of soil liquefaction occurring deeper than about 50 feet are
not likely to manifest at the ground surface.
Based on the field and laboratory data, and the analyses performed, it is anticipated that
large areas of the site would experience liquefaction under the assumed seismic event.
Significant settlements are anticipated to occur in conjunction with such an event. We
consider general site failure or lateral spreading unlikely because of the flat site
topography over most of the site. However, in the vicinity of Springbrook Creek,
shallow lateral spreading could occur since the soil on each side of the stream channel
is unconfined. Such lateral spreading could potentially impact pipelines and structures
located within the affected area.
5.2 DEWATERING
Given the subsurface conditions encountered, the existing groundwater level, and the
proposed invert level of the pipeline, provisions to control subsurface water during
construction of the South Interceptor Parallel should be anticipated. The following
section discusses alternative dewatering systems, impacts of dewatering, and disposal of
dewatering effluent.
5.2.1 Dewatering System Alternatives
General:
If groundwater is encountered during excavation of the trench, we recommend a
dewatering system be implemented during construction that lowers the piezometric
surface below the base of the excavation. The design and implementation of the
dewatering system should be the responsibility of the contractor. Potential dewatering
techniques may include, but are not limited to, coffer dams, vacuum well points, and
deep wells. Regardless of the dewatering technique used, it should be installed and
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operated such that natural soils are prevented from being removed along with the
groundwater.
If groundwater is encountered during construction within sand deposits, extreme care
should be taken to prevent groundwater from flowing into the excavation, thereby
creating a "quick" condition. Under "quick" conditions, the density of the natural
soils will be reduced, resulting in increased pipe settlement during and after
construction. Such conditions could also impact slope stability of open excavations.
To reduce the risk of creating a "quick" condition, we recommend the free water level
be kept at least 3 feet below the bottom of the excavation.
Based on the success of the dewatering methods used to construct the existing 72-inch
diameter interceptor, as described in Section 4.0, deep wells installed within the
underlying White River Sediments appear feasible for this project. Shallow wells and
closely spaced vacuum well points installed within the Overbank Flood Deposits may
also be used; however, the low permeability of this unit will greatly reduce the
effectiveness of these dewatering systems. Consequently, the spacing between the
wells may have to be reduced, thereby increasing the required number of wells or well
points.
As described in Section 4.0, the deep wells used for the construction of the existing 72-
inch diameter interceptor were installed along only one side of the trench on about 75-
foot centers. Sand boils along the trench bottom indicated that this space was too great
in many areas. Therefore, for planning purposes a spacing of between about 50 and 75
feet on center should be anticipated for deep dewatering systems. Well diameters,
spacing, depths, and pumping rates should be determined by qualified persons familiar
with dewatering system design. HWA can provide additional dewatering analysis if
desired. Should dewatering system design be performed by the contractor or others,
HWA should review the dewatering plan prior to construction.
Dewatering Adjacent to Wetlands:
During Phase II construction, sheet piles or other measures may be required in the
vicinity of the nearby wetlands in order to minimize potential impacts of the dewatering
system. In addition, similar shoring requirements may be required in areas to prevent
loss of ground support and possible distress to existing utilities. If, based on the design
of the sheet pile and dewatering system, it is determined that the water level in the
nearby wetlands will be affected, recharge wells may be required.
We suggest installing sheet piles in areas of observed standing water adjacent to the
interceptor at the time of construction. A contingency should be provided in the bid
documents for additional sheet piling, if during-construction monitoring indicates a
need for such. It is our opinion that the total length of sheet piling required for
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protection of the wetlands adjacent to the proposed interceptor may be reduced,
particularly if dewatering is performed within the sheet piles or on the side of the sheet
piles located furthest from the wetlands. This opinion is based on our general
understanding of site conditions; we have not performed detailed hydrogeologic studies
to evaluate the potential impact of dewatering on the nearby wetlands.
In order to define the relationship between groundwater, dewatering, and surface water
(wetlands), additional subsurface exploration, testing, and hydrogeologic evaluations
would be required. HWA can provide these services if required. Once such a study
has been performed, more definitive recommendations concerning the required lateral
extent of sheet piling required to protect the nearby wetlands could be provided.
5.2.2 Impacts of Dewatering
Based on our understanding of the project plans, it appears that the existing 72-inch
diameter sewer pipe, the two railroad crossings, Springbrook Creek, and the nearby
wetlands are major adjacent features that may be affected by a lowering of the water
table. The potential impacts of dewatering on these features are discussed below.
Dewatering of the utility trench will result in a lowering of the water table adjacent to
the excavation. As the water table is lowered, significant settlement of the surrounding
soil, in addition to the railroad tracks and the Springbrook Creek CMP's, could occur.
The magnitude of the settlement would depend on the amount of change in the water
level, the length of time the water was lowered, and the compressibility and
permeability of the soil. The magnitude of this settlement and potential impacts to
existing structures should be analyzed once a dewatering plan for the project has been
developed.
During dewatering and construction of the existing 72-inch diameter sewer pipe, the
effective stress on the soils beneath the pipe was increased. The higher effective stress
resulted in consolidation of the soils beneath the pipe. Once the dewatering operation
was terminated, the effective stress on the soils beneath the existing pipe decreased,
thereby resulting in minor rebounding of the soils. Dewatering the soils for the
proposed interceptor will similarly increase the effective stress on the soils beneath the
existing pipe. However, since these soils were previously consolidated, subsequent
dewatering will result in minor recompression of the soils with maximum settlements
expected to be within tolerable levels.
Due to the close proximity of Springbrook Creek to the central portion of the project
alignment, the impacts of dewatering on the creek were considered. However, due to
the low permeability of the Overbank Flood Deposits, we do not expect a significant
reduction in the water level of Springbrook Creek during limited periods of dewatering.
Also, if the special dewatering measures described in Section 5.2.1 are properly
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implemented during construction, we anticipate that dewatering can be completed with
only minimal draw-down adjacent to the wetlands.
5.2.3 Disposal of Dewatering Effluent
At this stage in the planning process, we understand the dewatering effluent will be
discharged to either a local storm sewer or recharge wells. Due to potential
environmental restrictions, we do not anticipate the disposal of dewatering effluent to
Springbrook Creek. Regardless of the method used to dispose of the dewatering
effluent, permits from appropriate agencies will be required. Accordingly, we
recommend that the time and cost associated with obtaining such permits be considered
in the construction schedule and budget. We also recommend that the dewatering
effluent be routed through sediment traps prior to disposal.
5.3 EXCAVATION AND SHORING
Due to the nature of the very soft/loose alluvial deposits, care must be taken during
construction to maintain stability of open excavations. The contractor should be aware
that on-site soils will not support vertical excavations without additional lateral support.
In addition, maintenance of safe working conditions, including temporary excavation
stability, is the responsibility of the contractor and all excavations must comply with
current federal, state, and local requirements. For planning purposes, it is
recommended that the proposed interceptor be installed within either open cut or shored
trench excavations. Specific recommendations for open cut and laterally supported
trench excavations are presented below.
5.3.1 Open Cut Excavations
Based on the soil conditions encountered in our subsurface explorations, the conditions
encountered during construction of the existing 72-inch diameter interceptor, and our
experience with similar soil types, it appears that the proposed interceptor could be
installed within a trench with open cut, unsupported side slopes. It is anticipated that
open cut temporary slopes up to 20 feet in depth with a maximum inclination of
11/211:1 V could be used during construction, provided an adequate dewatering system,
as described in Section 5.2, is operated and maintained during the excavation and sewer
installation process.
Due to the nature of the subsurface soils, localized sloughing of open cut trench side
walls may occur and should be anticipated. In addition, vibrations created by traffic
and construction equipment may cause some caving and raveling of trench walls. In
such areas, trench boxes or lateral support for the trench walls, as described below,
should be provided by the contractor to prevent loss of ground support and possible
distress to existing utilities and/or structures.
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I
We anticipated that excavation and pipe laying techniques similar to those used during
construction of Phase I (see Section 4.2) will be appropriate for Phase II construction,
provided an adequate dewatering system is operated and maintained and unanticipated
soil conditions are not encountered. However, it should be noted that successful
installation of the pipeline is also dependent on the contractor's methods and
experience. As such, the methods used during Phase I may or may not be successful
for Phase II, depending on the contractor's ability to implement the methods used to
successfully install the Phase I pipeline.
5.3.2 Laterally Supported Excavations
If conflicts with existing utilities, or the desire to preserve portions of the existing
pavement section and/or curbs and gutters of Oaksdale Avenue S.W., make the open
cut alternative unattractive, braced or cantilevered shoring support, such as driven
continuous or intermittent steel sheet piles, may be required. If cantilevered sh,et
piling is used, we estimate that the required depth of embedment below the base of the
excavation would be about 30 feet. If lateral bracing is used, the depth of the driven
sheeting could be significantly reduced. If braced sheeting is used, we estimate that the
required depth of embedment below the base of the excavation would be about 15 feet;
however, the actual depth of embedment required will depend on the location of the
bracing, the number of rows of bracing, and other factors.
The design of the shoring system should be performed by qualified persons with
experience in such designs. Lateral earth pressure diagrams for cantilevered and
multiple braced excavations were developed to aid in design of the shoring system.
These pressure diagrams are shown on Figure 9.
Recommendations for design and implementation of shoring and bracing systems for
the project are presented below.
• Shoring should be designed and constructed to support lateral loads
exerted by the soil mass, in addition to any surcharge loads from
construction equipment, construction materials, excavated soils, or
vehicular traffic.
I
• Sheet piles and steel sheets should be embedded in the Upper White
River Sediments at least 5 feet. However, a greater depth of
embedment may be required to maintain stability.
• Dewatering should begin well in advance of trench excavation.
During and after the excavation process, the bottom of the trench
should be at least 3 feet above the piezometric groundwater surface.
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• At locations where settlement could be detrimental to adjacent
structures, utilities, or pavements, the shoring system should be
designed to prevent significant lateral movement of the existing soils.
• Precautions should be taken during removal of the shoring or
sheeting materials to minimize disturbance of the pipe, underlying
bedding materials, and natural soils.
• Heavy construction equipment, construction materials, excavated
soil, and vehicular traffic should not be allowed within a distance,
measured from the edge of the excavation, equal to one-third the
depth of the excavation, unless the shoring system has been
specifically designed to support the additional loads.
5.4 RAILROAD TRACK UNDER-CROSSING
We understand that conventional open excavation and backfill methods for the
installation of the proposed interceptor may not be feasible at the railroad under-
crossing and that either jacking or tunneling techniques may be used at this location.
Of the two construction methods being considered, the tunneling alternative would
probably be more expensive and less attractive than the jacking alternative.
Based on the subsurface conditions observed in the exploratory borings and soundings,
it is anticipated that conventional jacking methods could be used to install the pipe
under the railroad tracks. The following sections discuss the design and construction
considerations associated with jacked pipe installations. If the project team elects to
pursue the tunneling alternative, geotechnical recommendations regarding this option
could be provided at a later time.
5.4.1 Design Considerations for Jacked Pipe Installations
Jacking pits will be required on each side of the jacked section of pipe. In order to
minimize the disturbance of the surrounding soil in the vicinity of the railroad
crossing, it may be necessary to construct temporary retaining structures along all four
sides of each jacking pit, forming an enclosed cell, or cofferdam. The design of the
temporary shoring systems, in addition to determining the size and depth of the jacking
pits, should be the responsibility of the contractor. In addition, the contractor should
determine the number and capacity of jacks required, based on anticipated soil types,
pipe size, and jacking distance.
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The earth pressure diagrams shown on Figure 9 may be used to aid in design of the
temporary shoring system for the jacking pits. Due to the soft/loose nature of the
native soils, the temporary shoring system should be designed to accommodate lateral
loads from the jacking abutment. Furthermore, the jacking abutment should be
designed such that the jacking force is uniformly distributed to the shoring system.
5.4.2 Construction Considerations for Jacked Pipe Installations
The usual construction sequence for jacking concrete pipe begins with the excavation of
pits on each side of the jacked section of the alignment. A steel or wood jacking
abutment is then installed against the far wall of the entrance pit. Hydraulic jacks and a
jacking frame are then installed.
Once the entrance pit has been prepared as described above, the first section of pipe is
equipped with a cutter, or shoe, lowered into the pit, positioned on the jacking frame,
and jacked forward. Material within the jacked section of pipe is then removed
through the pipe. The succeeding section of pipe is then lowered between the jacks and
the lead pipe and jacked forward. The excavation, soil removal, pipe insertion, and
jacking sequence is repeated until the lead section of pipe enters the receiving pit.
General recommendations pertaining to the jacking of concrete pipe are presented
below:
• Dewatering should begin prior to excavation of the entrance and
receiving pits. During and after the excavation process, the
bottoms of the jacking pits should be at least 3 feet above the
piezometric groundwater surface.
• Prior to jacking pipe, the jacking direction should be established
and guide rails installed in the bottom of the entrance pit. The
guide rails should be carefully set in a concrete slab.
• The lead pipe should be contained within a shield or equipped
with a cutter or shoe to protect the pipe from the mining
equipment used to excavate the tunnel bore.
• The stroke of the jack should be as long as possible to reduce the
number of spacers required, thereby reducing installation time
and cost. Ideally, the need for spacers would be eliminated by
using a jack with a stroke greater than the length of the pipe
section being jacked.
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• In order to minimize disturbance of natural soils adjacent to the
pipe, the material at the face of the tunnel bore should be
trimmed with care and the excavation should not excessively
precede the jacking operation.
• If needed, a bentonite slurry may be pumped between the tunnel
bore and the outside of the pipe to reduce frictional resistance.
• Once the jacking operation begins, the operation should be as
continuous as possible, thereby reducing the tendency of the
pipes to "set" when forward motion is interrupted.
• After the pipes have been jacked into their final positions, the
space between the tunnel bore and the outside of the pipe should
be backfilled with a pumpable grout.
5.5 SPRINGBROOK CREEK UNDER-CROSSING
At about Station 82+75, the proposed interceptor will cross under Springbrook Creek,
which is transmitted under Oaksdale Avenue S.W. by four CMP's. Due to the vertical
alignment of the proposed interceptor, there is not sufficient space between the top of
the proposed interceptor and the bottom of the CMP's to install the proposed 108-inch
diameter pipe. As a result, a low head structure with transition sections to the pipeline
on either side of the crossing will be required at this location.
Three alternative construction techniques for the Springbrook Creek crossing are
currently being considered. The alternatives include (1) temporarily supporting the
CMP's and constructing a conventional rectangular concrete box structure, (2)jacking
two 84-inch diameter concrete pipes in place, and (3)jacking a pre-cast rectangular
structure into place. The following sections describe our geotechnical
recommendations pertaining to each alternative.
5.5.1 Temporary Support for Springbrook Creek CMP's
Under this alternative, we understand the four CMP's would be temporarily supported
by hangers suspended from a braced frame composed of steel beams supported on four
piles. It is anticipated that the spacing between the piles would be about 18 feet across
the sewer trench and about 26 along the sewer trench. Considering this spacing, we
estimate that each pile would be required to support a working load of about 16 tons.
Recommended pile types for support of the braced frame include driven steel H-piles,
steel pipe piles, and timber piles. In order to provide a capacity of 16 tons, the piles
should penetrate the Upper White River Sediments by about 10 feet, thereby resulting
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in a total pile length of about 25 feet. However, actual penetration depths of the piles
should be based on actual driving resistance. Pile driving criteria should be developed
by the geotechnical consultant, using wave equation or other appropriate methods.
Once the existing CMP's have been supported by the pile supported frame, the material
beneath the CMP's would be removed and a cast-in-place, low head, rectangular
structure would be constructed. Due to the difficulty in adequately backfilling the
narrow space between the suspended CMP's and the top of the low head structure, a
Controlled Density Fill (CDF) should be used to fill the void.
5.5.2 Jacking Circular Pipes under Springbrook Creek
The second alternative for the Springbrook Creek crossing consists of individually
jacking two side-by-side, 84-inch diameter pipes under the Springbrook Creek CMP's.
On each side of these pipes, transition structures connected to the 108-inch diameter
interceptor would be required. Since the pipes would be jacked under the Springbrook
Creek CMP's, this alternative eliminates the need to backfill the small space between
the tops of the pipes and the bottoms of the CMP's.
The geotechnical design and construction recommendations presented in Section 5.4.1
and 5.4.2 are considered applicable to the jacking of the two pipes under the
Springbrook Creek CMP's, and should be reviewed for additional details.
5.5.3 Jacking a Rectangular Structure under Springbrook Creek
The third alternative for the Springbrook Creek crossing includes the concept of jacking
a pre-cast, concrete, low head, rectangular structure into place. Due to the difficulty
and expense associated with jacking a rectangular concrete structure, this alternative is
considered the least desirable. As a result, specific geotechnical recommendations for
this alternative will not be addressed at this time. However, if the project team decides
to further pursue this alternative, geotechnical recommendations for the jacking of the
rectangular structure could be provided.
5.6 PIPE SUPPORT AND TRENCH BACKFILL
Based on our field explorations, we anticipate the exposure of variable but generally
adequate subsoil conditions at pipe invert elevations; commonly loose to medium
dense, poorly graded sand with silt to silty sand. Relatively undisturbed natural soils
should provide suitable support for the proposed interceptor; however, if soft silt, clay,
or organic-rich soil is exposed along the bottom of the trench, we recommend it be
removed and replaced with properly compacted structural fill as described below.
i
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5.6.1 Pipe Bedding
Pipe bedding material, placement, compaction, and shaping should be in accordance
with the project specifications and the pipe manufacturer's recommendations. As a
minimum, the pipe bedding should meet the gradation requirements for Bedding
Material for Rigid Pipe, as described in Section 9-03.15 of the 1994 WSDOT Standard
Specifications for Road, Bridge, and Municipal Construction.
General recommendations relative to the bedding of the proposed sewer pipe are
presented below:
• Pipe bedding materials should be placed on relatively undisturbed
alluvium, or compacted fill soils. If the alluvial subgrade soils are
disturbed, the disturbed material should be removed and replaced
with compacted bedding material.
• In areas where the trench bottom encounters very soft or organic-
rich subgrade soils, it may be necessary to over-excavate the
unsuitable material and backfill with imported granular fill prior to
placing pipe bedding material. The granular backfill material
should meet the gradation requirements for Foundation Gravel, as
described in Section 9-03.17 of the 1994 WSDOT Standard
Specifications for Road, Bridge, and Municipal Construction.
• A minimum 6-inch thickness of bedding material should be provided
beneath the pipe. Larger thicknesses may be necessary to prevent
loosening and softening of the natural soils during pipe placement.
• Pipe bedding material should be placed in maximum 6-inch loose
lifts and compacted to a density of at least 90 percent of the
maximum dry density, as determined by ASTM D 1557 (Modified
Proctor).
• Prior to the installation of the pipe, the pipe bedding should be
shaped to fit the lower part of the pipe exterior with reasonable
closeness to provide continuous support along the pipe.
Alternatively, CDF (minimum 7 day compressive strength of 500
psi) placed on top of properly compacted bedding material may be
used as a "cradle" for the lower portion of the concrete pipe.
• If a CDF cradle is used beneath the pipe, it should be at least 6
inches thick and should extend up the sides of the pipe a height
equal to one-fourth the outside diameter of the pipe. The cradle
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should have a minimum width at least equal to the outside diameter
of the pipe plus 8 inches.
• Pre-cast concrete pipe supports should be provided on each side of
the joints between sections of pipe.
• Bedding around the pipe should be placed in layers and compacted
to obtain complete contact with the pipe. The bedding material
should be placed to a depth of at least 12 inches above the top of the
pipe.
• Once the trench has been completely backfilled, all shoring,
including sheeting, should be removed in a manner that prevents
disturbance to the pipe bedding. Shoring that is in direct contact
with CDF, if used, should be treated with a bond breaker to ensure
removal with minimum disturbance to the CDF.
5.6.2 Trench Backfill
In paved roadway and shoulder areas, we recommend that trench backfill consist of
Bank Run Gravel for Trench Backfill, as described in Section 9-03.19 of the 1994
WSDOT Standard Specifications for Road, Bridge, and Municipal Construction.
During placement of the initial lifts, the trench backfill material should not be
bulldozed into the trench or dropped directly on the pipe. Furthermore, heavy
vibratory equipment should not be permitted to operate directly over the pipe until a
minimum of 3 feet of backfill has been placed.
In order to minimize subsequent settlement of the trench backfill, it is recommended
that the trench backfill be placed in 8- to 12-inch, loose lifts and compacted using
mechanical equipment to at least 90 percent of the maximum dry density as determined
by ASTM D 1557 (Modified Proctor). In areas beneath the roadway pavement,
shoulders, and curbs, the upper 2 feet of the backfill, as shown on Figure 10, should be
compacted to at least 95 percent to provide an adequate subgrade for the pavement and
traffic loads. In areas where some settlement can be tolerated, such as landscape areas,
it is recommended that the backfill material be placed in loose lifts not exceeding 2 feet
and that each lift be compacted to at least 85 percent, with the upper 2 feet compacted
to at least 90 percent (see Figure 10).
It is anticipated that selected excavation spoils may be used as trench backfill if they are
placed at or near optimum moisture content and proper compaction control is utilized.
However, the native soils may be too wet to achieve the recommended compaction
requirements. If the material is not compacted as recommended, the potential for
backfill settlement may be increased. Therefore, excavation spoils should only be used
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in areas where post-construction settlements up to several inches above the top of the
pipe can be tolerated. In addition, if the native soils are to be used as trench backfill,
the height of the bedding material above the top of the pipe should be increased to at
least 4 feet, to minimize buoyancy uplift of the pipe during a seismic event.
5.7 EXTERNAL LOADS IMPOSED ON BURIED PIPE
In general, the load imposed on a buried pipe is dependent on several factors, including
the flexibility of the pipe, subsurface conditions, backfill conditions, width of the
trench, height of the backfill above the pipe, method of installation, an any surcharge
loads. For this project, backfill loads on a 108-inch diameter rigid reinforced concrete
pipe were estimated, assuming a backfill unit weight of 120 pounds per cubic foot
(pcf), for various depths of installation. In addition, vehicle live loads, including
impact factors, for HS-20 truck loading and Cooper E-80 train loading were estimated
using the methods presented in the "Concrete Pipe Design Manual," published by the
American Concrete Pipe Association, 1987 printing.
The estimated backfill and traffic loads, in pounds per lineal foot (plf), on the rigid
concrete sewer pipe for various depths of installation are presented in Table 3. Backfill
and traffic loads for intermediate fill heights may be interpolated. If changes are
proposed involving the size, type, or depth of the pipe, HWA should be notified for
review and revision of the estimated loads.
Table 3.
Estimated Externally Imposed Loads on Rigid
108-inch Diameter Sewer Pipe
Depth Estimated Live Estimated Live Estimated Load Estimated Load
to Top Load due to Load due to due to Backfill due to Backfill
of HS-20 Truck Copper E-80 (trench (jacked
Pipe Loading Train Loading installation; installation;
(feet) ( l f)(1) ( lf)(2) lf)(3) lf)(4)
5 1,330 18,800 7,000 6,000
10 650 8,740 15,000 11,000
15 NA 5,220 21,300 15,000
(1) Beyond a depth of 12 feet, truck live loads are considered insignificant. The
estimated truck loads include impact factors.
(2) Weight of track structure assumed to be 200 pounds per linear foot. The
estimated train loads include impact factors.
(3) Assumes a sand and gravel backfill weighing 120 pcf and a 14-foot wide trench
at the top of the pipe.
(4) Ignores the effect of cohesion of the soil along the limits of the prism of soil over
the bore, which slightly reduces the vertical earth load on the pipe.
93093R.DOC 25 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
5.8 BURIED STRUCTURES
Due to the high groundwater conditions along the project alignment, closed
interconnection structures such as vaults or manholes may be subjected to buoyant
uplift forces. Consequently, these elements should be designed to resist buoyant
forces. Uplift resistance may be provided by extending a flange at the bottom of the
buried structure. The weight of the soil directly over the flange assists in resisting
buoyant forces. Uplift resistance from backfill placed around these structures may be
determined utilizing the equivalent fluid unit weights presented in Table 4.
Table 4.
Unit Weights for Backfill Soils
Equivalent Fluid
Soil Type Groundwater Condition Unit Wei ht ( cf)
Native soil Above water table 110 pef
Native soil Below water table 45 pcf
Granular backfill Above water table 120pcf
Granular backfill Below water table 55 cf
Buried structures should also be designed to resist lateral forces exerted by the
surrounding backfill. For use in design, at-rest earth pressures equivalent to a fluid
weighing 60 pcf and 30 pcf, respectively, may be used for backfill soils above and
below the water table. In addition to the equivalent fluid weights for soil, hydrostatic
forces should be applied below the groundwater level.
5.9 PIPE SETTLEMENT
The imposed vertical stress on bearing soils from the buried pipe is expected to be less
than or close to the existing stress on the natural soils. Therefore, the soil at the
bearing elevation should experience very little, if any, increase in stress, provided
subgrade soils are not disturbed significantly during excavation and pipe installation.
Because of the small increase in stress, total post construction settlement of less than 2
inches, with differential settlements of less than 1 inch, is anticipated for properly
bedded pipe placed on relatively undisturbed natural soils. However, disturbance of ,
the bearing soils would result in increased settlement. Settlement of the proposed
pipeline will therefore be dependent upon the amount of disturbance of the bearing
soils, as well as the loads imposed on the subgrade soils.
i
93093R.DOC 26 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
6.0 UNCERTAINTY AND LIMITATIONS
The conclusions, recommendations, and opinions presented herein are (1) based upon
our evaluation and interpretation of the findings of our field and laboratory programs,
(2) based upon an interpolation of subsurface conditions between the exploratory
borings and CPT soundings, (3) based upon our understanding of the site layout and
improvements as described herein, (4) subject to confirmation of the actual conditions
encountered during construction, and (5) based on the assumption that sufficient
geotechnical observation, testing, and monitoring will be provided during construction.
Experience has shown that subsurface soil and groundwater conditions can vary
significantly over small distances. Inconsistent conditions can occur between
explorations and not be detected by a geotechnical study. If, during future site
operations, subsurface conditions are encountered which vary appreciably from those
described herein, HWA should be notified for review of the recommendations of this
report, and revision of such if necessary.
This report is issued with the understanding that is the responsibility of the owner, or
his representative, to ensure that the information and recommendations contained herein
are brought to the attention of appropriate design team personnel and incorporated into
the project plans and specifications, and the necessary steps are taken to see that the
contractor and subcontractors carry out such recommendations in the field.
Within the limitations of scope, schedule, and budget, HWA attempted to execute these
services in accordance with generally accepted professional principles and practices in
the fields of geotechnical engineering and engineering geology in the area at the time
the report was prepared. No warranty, expressed or implied, is made.
This firm 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 he considers any of the
recommended actions presented herein unsafe.
93093R.DOC 27 HONG WEST& ASSOCIATES, INC.
September 19, 1994
HWA Project No. 93093
7.0 REFERENCES
i
American Concrete Pipe Association, 1980, Concrete Pipe Handbook.
American Concrete Pipe Association, 1987, Concrete Pipe Design Manual.
Blake, T.F., 1989, LIQUEFY2, A Computer Program for the Empirical Prediction of
Earthquake-Induced Liquefaction Potential, User's Manual, 1986, 87p.
Galster, R.W. and W.T. Laprade, 1991, Geology of Seattle, Washington, United States
of America, Bulletin of the Association of Engineering Geologists, Vol. 28, No. 3,
August 1991.
Golder Associates, Inc., 1992, Geotechnical Engineering Study for Proposed 108-inch
Diameter Metro Sewer, Boeing-Longacres Park Development, Renton, Washington,
unpublished consultant report prepared for Sverdrup Corporation, August 14, 1992.
Grant, W.P., W.J. Perkins, and T.L. Youd, 1992, Evaluation of Liquefaction
Potential, Seattle, Washington, U.S. Geological Survey, Open-File Report 91-441-T,
44p.
HDR Engineering, Inc., C112M Hill, Adolfson Associates, Inc. and Fujiki and
Associates, Inc., 1992, South Interceptor Validation Study, Alternative Development
and Workshop and Final Alternative Development, unpublished technical memorandum
prepared for the Municipality of Metropolitan Seattle, September 22, 1992.
Jefferies, M.G. and M.P. Davies, 1992, Use of CPT Data to Estimate Equivalent SPT
N60, submitted to ASTM Geotechnical Testing Journal.
Metropolitan Engineers, 1967, Final Report, Soils Investigation, South Interceptor,
Section 2, Renton and Kent, Washington, unpublished report, October 30, 1967.
Mullineaux, D.R., 1965, Geologic Map of the Renton Quadrangle, King County,
Washington, U.S. Geologic Survey, Map No. CQ-405.
Mullineaux, D.R., 1970, Geology of the Renton, Auburn, and Black Diamond
Quadrangles, King County, Washington, U.S. Geologic Survey, Professional Paper
672.
Robertson, P.K. and R.G. Campanella, 1986, Guidelines for Use, Interpretation and
Application of CPT and CPTu, Third Edition, Soil Mechanics Series No. 79,
University of British Columbia, Vancouver, 196p.
93093R.DOC 28 HONG WEST& ASSOCIATES, INC.
I
September 19, 1994
HWA Project No. 93093
Seed, H.B. and I.M. Idriss, 1982, Ground Motions and Soil Liquefaction During
Earthquakes, Earthquake Engineering Research Institute, 134p.
Seed, H.B., K. Tokimatsu, L.F. Harder, and R.M. Chung, 1985, Influence of SPT
Procedures in Soil Liquefaction Resistance Evaluation, ASCE Journal of Geotechnical
Engineering Division, Vol. 111, No. GT12, pp. 1425-1445.
Shedlock, K.M. and C.S. Weaver, 1991, Program for Earthquake Hazards Assessment
in the Pacific Northwest, U.S. Geologic Survey Circular 1067.
Skempton, A.W., 1986, Standard Penetration Test Procedures and the Effects in Sand
of Overburden Pressure, Relative Density, Particle Size, Ageing, and
Overconsolidation, Geotechnique 36, No. 3, pp. 425-447.
Uniform Building Code, 1988, International Conference of Building Officials, 926p.
Washington State Department of Transportation/American Public Works Association,
1994, Standard Specifications for Road, Bridge, and Municipal Construction.
Woodward-Clyde Consultants, 1992, Seismic Hazard Evaluation for the Cedar Falls
Dam, unpublished consultant report prepared for Seattle Water Department, December
1992.
93093R.DOC 29 HONG WEST& ASSOCIATES, INC.
Syr 16th ST
"—SIB
LONGACRES
4 RACE TRACK
}
PROJECT W
SITE
SW 34th ST
a SW 41st ST
S 180th ST SW 4Jrd ST
0 1280 2560 5120
SCALE, 1'=2560'
SOUTH INTERCEPTOR VICINITY MAP
��WEST PARALLEL: PHASE ZL
&ASSOCIATES,INC. PROJECT NO.: 93093 FIGURE:
93093-A-020.0
LEGEND
BH-2 APPROXIMATE LOCATION AND DESIGNATION OF BOREHOLE
BY HWA, 1993
— CPT-2 APPROXIMATE LOCATION AND DESIGNATION OF
l CONE PENE_7RATION TEST (CPT) SOUNDING BY HWA, 1993
B33 T APPROXIMATE LOCATION AND DESIGNATION OF BOREHOLE
BY METROPOLITAN ENGINEERS, 1967
7 6 4
5 3
165,338 $ 201 ,993 $ 201 ,673 $ 223,015 $
200,041
I I
I
I I I II � II
I W W.I I I
W i 40' 40' I J
Z
IW it W "
\ °° � CPT-6 a =
y R-55.00 I M y R=55.00 16 I JS
G_90r00 OCfp=90'00'0crR=5."R - 35 00 f L=86.39 3 L^8639 p=& y 3 p=W38'2d'
L —17'W h � �_7EL N v L-BfL-87.01
--Tg W - - - W— , W--SD --, —Y W TELJ � (N —aEL
R 75.00 '� ST0. 55+87.9
52+00 53+00 54+00 55+ 0 �- TEL
�1 0
I 56+ 57+DO 58+ ,, SSp y
N 01'01'5YE 192.18 y N Oi'30'19'E 210.05 I' I_ 1 __ I +� +� 61+ a 62+00 +� ASS `:.�"- —17'
0 I_ ,_ t00 65+00
._p_._ b N Oi'29'54'E 3,6.53 y _426.845 6 N 0,'29'54.E I C J OAKESDALE AVE 8 1 N 01'29'54'E
\ �2" 5T0. �V_ R(/AKE$D —L] _
�r se+se.a ALE AVE �� c --_.�—
;,� _gam— ST0. 60+25.3
R- 35.00
�=90'00'0fl R!��90'00'00'
Z Z L=88.39 w
N N �
N N M
IM I
13 I
z N SE 1/4 SEC.25 T23N R,',E
�. �.
I I
I I
I
0 50 100 200 SITE AND EXPLORATION PLAN
' SCALE: 1'=100' SOUTH INTERCEPTORSTA 51 +00 TO 65+50
BASE MAP PROVIDED BY GARRY STRUTHERS ASSOCIATES, INC. NNGWST PARALLEL: PHASE ]L
&ASSOCIATES.INC. PROJECT NO.: 93093 FIGURE: 2
93093—ad}-bmap
I
2 1
\ z
193,146 0 ,'57,764 [ _
I I \ Q
z I I \
\ �ti
�r
OL
9ti C�
to
r
3 Imi
_ o
b $ T N BH-3 636
u a
—7FL n
T$-- z tiS¢ R=483.34 \
—_ —' ice- —. ._- / A=14'I T54'
tY M 1YW --TEL— __
�-- - T _L=115.63
_gss + 88+00 89 logo
0 70+00 r,71+00 7z+00 OAKESDALE AVE
' ' 07�+oo DO
74+00
--111'-- -'- ' ' .J v 78+00 77+ 78+00 79
N OP29'S4'E 9 -�- d
OAKESDALE AVER N Ot'29 �'E 157 yam'—J J
v — 'mowST,t 73+08.75 N 0-1y52-9-37"E 514.15 -!SrS-
,Py N
b N R=55.00 I R=55.00 1/16 SEC110N UNE—
S A=90'00'001' A=90'0 oor t
cc
N I °a Lr BS..S9 t
� N �
Z I @I
UI
3
30. 30. SE 1/4 SEC.25 T 23N R4E
i I
I I I I
I 1 I
134,822 01 2
142,3040
�Q
BH—Z APPROXIMATE
LOCATION AND DESIGNATION OF BOREHOLE
BY HWA, 1993
CPT-2 APPROXIMATE LOCATION AND DESIGNATION OF
CONE PENETRAnON TEST (CPItj SOUNDING BY HWA, 1993
B33 APPROXIMATE LOCATION AND DESIGNATION OF BOREHOLE
BY METROPOLITAN ENGINEERS, 1967
0 50 100 200 SITE AND EXPLORATION PLAN
SCALE: 1"-100, iiiii =A SOUTH INTERCEPTOR STA 65+50 TO 79+00
BASE MAP PROVIDED BY GARRY STRUTHERS ASSOCIATES, INC. flONGWEST PARALLEL: PHASE IL
&ASSOCIATES,INC. PROJECT NO.: 93093 FIGURE: 3
93093-ad}-bmap
IFS
BH-2 APPROXIMATE LOCATION AND DESIGNATION OF BOREHOLE
T BY HWA. 1993
CPT-2 - APPROXIMATE LOCATION AND DESIGNATION OF
CONE PENETRATION TEST (CI-7) SOUNDING BY HWA, 1993
B33 + APPROXIMATE LOCATION AND DESIGNATION OF BOREHOLE
BY METROPOLITAN ENGINEERS, 1967
40'
Z
J
JP W II
3
d
vi
BH-1 kkkk I
CPT-3 R - 55.00 SO-._ � R - 55.00 CPT-1 I
L = S& -� L - 8&00 I ;
—1YW— A 83+1 87� —SD —° ° — — _ f w B37 I 48'
81+00 ,�== - .�--
_ 82+ \ +00 '84+00�"._� 85+00 -S.S RIF
I 86+00 87+00 88+00 89+00 'I
0 N 01.47-,0' 332.95 - _ W+aF 91+00 9
941' as -
5 — — -Ss— \\ k —Ss— i �� N ors3ssE 99z.63 OAKESDALE AVE h - i 93+
W - - _ -Ss-
� v -SS- -SS
OY it // .. - - _
BH-2 I/I6 SECTION UNE- - O
1Z ,� CPT-2
rN- H
R-463.34 N M
A=1936.41< V
L=150.52 W W �. SO'
N
NE 1/4 SEC.36 T23N R4E
70' R.R. Raw.
0 5o 100 200 = SITE AND EXPLORATION PLAN
SOUTH INTERC=PTOR STA 79+00 TO 93+00
BASE MAP PROVIDED BY GARRY STRUTHERS ASSOCIATES, INC. SCALE. 1"—_100' flONGWEST PARALLEL: PHASE ZL
ASSOCIATES,INC. PROJECT NO.: 93093 FIGURE: 41 93093-ad}-bmop
B33 CPT-6 BH-4
(PROF W.) (PROF W.)
120 Oc (tsf) 120
0 50 100 '150 200 250
VERY SOFT TO SOFT, DARK GRAY, SILT TO 3
SANDY SILT WITH ORGANIC MATTER AIJD SOME 2
110 PEAT LAYERS (OVERBANK FLOOD DEPOSITS) 2 110
4
? ? ? ? — ? ? ?
11
100 —_ 1001
PROPOSED 108—INCH LOOSE TO MEDIUM DENSE, VERY DARK GRAY TO < SILT 7
DIAMETER INTERCEPTOR DARK GRAY, POORLY GRADED SAND NTH SILT
TO SILTY SAND. (UPPER WHITE RIVER SEDIMENTS) —?
22
90 90
26
?
80 w __- ? ? �_ ' 25 80
1� ? ALTERNATING SEQUENCE` OF VERY SOFT, DARK GRAY ?
Z — ? TO VERY DARK GRAY, SILT AND LEAN CLAY WITH 2
0 —� INTERBEDS OF VERY SOFT ORGANIC CLAY AND LOOSE
a �"�_ TO MEDIUM DENSE SILTY SAND. (LOWER WHITE RIVER P
w LEGEND SEDIMENTS)
J
w 0 70
70 APPROXIMATE LOCATION AND DESIGNATION OF BOREHOLE ? —'---
BH-2 BY HWA, 1993 �" ?
12 STANDARD PENETRATION TEST (SPT) LOCATION WITH MEDIUM DENSE TO DENSE, VERY DARK GRAY 10 ?
PENETRATION RESISTANCE IN BLOWS PER FOOT TO DARK GRAY, SILTY SAND WITH SOME
SHELL FRAGMENTS. (CEDAR RIVER DELTAIC
P PUSHED SAMPLE DEPOSITS)
60 OBSERVED OR ESTIMATED GROUNDWATER ELEVATION 60
CPT-2 — APPROXIMATE LOCATION AND DESIGNATION OF
CONE PENETROMETER TEST (CPT) SOUNDING BY HWA, 1993
w goo I o CONE PENETROMETER TIP RESISTANCE (Oc) WITH DEPTH
50 50
B33 APPROXIMATE LOCATION AND DESIGNATION OF BOREHOLE
f BY METROPOLITAN ENGINEERS, 1967
?_ ASSUMED GEOLOGIC INTERPRETATION FOR AREAS BETWEEN
EXPLORATIONS (FOR GRAPHICAL PURPOSES ONLY)
40 40
50+00 55+00 60+00 65+00
NOTE:
THIS GENERALIZED SOIL PROFILE WAS COMPILED FROM AVAILABLE GENERALIZED GEOLOGIC
SUBSURFACE INFORMATION. IT IS INTERPRETIVE IN NATURE; ACTUAL
SOIL CONDITIONS BETWEEN EXPLORATIONS MAY VARY FROM SCALE: 1"=100 HORIZONTAL 1"=10 VERTICAL =A SOUTH INTERCEPTOR CROSS SECTION
THOSE SHOWN. floNG111 M PARALLEL: PHASE II STA. 50+00 TO STA. 65+50
&ASSOCIATES,INC. PROJECT NO.: 93093 FIGURE: 5
93093—B-001.2
CPT-5 8H-3 B36
(PRO W.) (PRO E.)
120 Oc (tsf) 120
0 50 100 150 200 250
VERY SOFT TO SOFT, DARK GRAY, SILT TO
SANDY SILT WITH ORGANIC MATTER AND 0
110 SOME PEAT LA'.,'ERS. (OVERBANK FLOOD
DEPOSITS) 2 110
— 0 _
SILTY SAND WITH _
? ? ? ? INTE BEDS OF
PEAT AND SILT
100 \2
? 100
11
PROPOSED 108—INCH LOOSE TO MEDIUM DENSE, VERY DARK GRAY
DIATEMTER INTERCEPTOR TO DARK GRAY POORLY GRADED SAND WITH
SILT TO SILTY SAND. (UPPER WHITE RIVER 20
90 SEDIMENTS) 90
20
w / w
25
z 80 ? Z / 80 zz
? ? ? ?
>
0
P SILTY SAND/ >
W
? � w
q
ALTERNATING SEQUENCES OF VERY SOFT, DARK GRAY 13 �
70 TO VERY DARK GRAY, SILT AND LEAN CLAY WITH -� 70
INTERBEDS OF VERY SOFT ❑RGANIC CLAY AND LOOSE
TO MEDIUM DENSE SILTY SAND. (LOWER WHITE RIVER
SEDIMENTS) 1
60 1 ? 60
MEDIUM DENSE TO DENSE, VERY DART( GRAY ? �_
TO DARK GRAY, SILTY SAND WITH SOME 31 ?
SHELL FRAGMENTS. (CEDAR RIVER D'._LTAIC
DEPOSITS)
50 50
40 40
66+00 70+00 75+00 79+00
NOTE: 000
THIS GENERALIZED SOIL PROFILE WAS COMPILED FROM AVAILABLE GENERALIZED GEOLOGIC
SUBSURFACE INFORMATION. IT IS INTERPRETIVE IN NATURE; ACTUAL SCALE: 1"=100' HORIZONTAL
SOIL CONDITIONS BETWEEN EXPLORATIONS MAY VARY FROM THOSE 1"=10' VERTICAL • SOUTH INTERCEPTOR CROSS SECTION
SHOWN. SEE FIGURE 5 FOR LEGEND OF SYMBOLS. flON �G7! PARALLEL: PEASE II
V STA. 65+50 TO STA, 79+00
&ASSOCIATES,INC. PROJECT NO.: 93093 FIGURE: 6
93093-B-002.1
CPT-4 BH-2 BH-1 CPT-2 CPT-1
(�� W) (Ptoa. 21.5' c.) (P1toa 21.2' �) (��' E.) (PR�w)
Oc (tsf)
120 0 50 100 160 200 250
ac (tsf) Oc (tsf) 120
0 70 Soo 150 200 250 0 30 100 '150 200 250
13 8
VERY SOFT TO SOFT, DARK GRAY,
12 7 SILTY TO SANDY SILT WITH ORGANIC
MATTER AND SOME PEAT LAYERS
110 3 (OVERBANK FLOOD DEPOSITS) 110
0-
0- 11 ? � ? ?
100 9 100
18 6
PROPOSED 108—INCH
LOOSE TO MEDIUM DENSE, VERY DARK DIAMETER INTERCEPTOR
12 GRAY TO DARK GRAY, POORLY GRADED
12 24 SAND WITH SILT TO SILTY SAND.
90 ? (UPPER WHITE RIVER SEDIMENTS) 90
4 1 0
P
w 0 1 _ ? ? ?
0 8p P 80
0
> 0
W
W
20 SILTY SAND 17-
70--L--IL ? � 70
0 0 ALTERNATING SEQUENCES OF VERY SOFT, DARK GRAY
TO VERY DARK GRAY, SILT AND LEAN CLAY WITH
INTERI3EDS OF VERY SOFT ORGANIC CLAY AND LOOSE
p 0 TO MEDIUM DENSE SILTY SAND. (LOWER WHITE RIVER SEDIMENTS)
60 ? ? 60
8 SILTY SAND 4
�-- ?
50 ? 50
MEDIUM DENSE TO DENSE, VERY DARK GRAY 9 ?
TO DARK GRAY, SILTY SAND WITH SOME SHELL
FRAGMENTS. (CEDAR RIVER DELTAIC DEPOSITS)
40 40
79+00 80+00 85-00 90+00 93+00
NOTE:
THIS GENERALIZED SOIL PROFILE WAS COMPILED FROM AVAILABLE GENERALIZED GEOLOGIC
SUBSURFACE INFORMATION. IT IS INTERPRETIVE IN NATURE; ACTUAL 1
SOIL CONDITIONS BETWEEN EXPLORATIONS MAY VARY FROM THOSE SOUTH INTERCEPTOR CROSS SECTION
SHOWN. SEE FIGURE 5 FOR LEGEND OF SYMBOLS. SCALE: 1"=100' HORIZONTAL ���
1"=10' VERTICAL PARALLEL: PHASE II STA. 79+00 TO STA. 93+00
&ASSOCIATES,INC.
PROJECT NO.: 93093 FIGURE: 7
93093-B-003.1
41+1
CPT-6 BH-4 CPT-5 BH-3 CPT-4 CPT-2
BH-2 CPT-3 CPT-1
120 I BH-1 I 120
------------
OVER:BANK
FLOOD
DEPC)SI TS
110 110
100 100
PROPOSED 108-INCH UPPER WHITE
DIAMETER INTERCEPTOR RIVER SEDIMENTS
90 80
P\
\ ? 80
80 -
< \ ? .
LOWE:R WHITE
RIVER SEDIMENTS
70 \ 70
- 60
ISO CEDAR RIVER
DELTIC DEPOSI IS
LEGEND
50 - ASSUMED GEOLOGIC INTERPRETATION '�?� 50
FOR AREAS BETWEEN EXPLORATIONS (FOR
GRAPHICAL PURPOSED ONLY)
LIQUEFIABLE SOIL ZONES UNDER
100-YEAR SEISMIC EVENT
40 40
NOTE:
THIS GENERALIZED SOIL PROFILE WAS COMPILED FROM AVAILABLE
SUBSURFACE INFORMATION. IT IS INTERPRETIVE IN NATURE; ACTUAL SCALE: 1"=400' HORIZONTAL SOUTH INTERCEPTOR LIQUEFIABLE
OF POTENTIALLY
SOIL CONDITIONS BETWEEN EXPLORATIONS MAY VARY FROM "=10' VERTICAL
THOSE SHOWN. floNG%VM PARALLEL: PHASE IL LIQUEFIABLE ZONES
1
&ASSOCIATES►INC. PROJECT NO.: 93093 FIGURE: 8
93093-B-009.2
15'
SOFT SILT
Hi
Hw
P2 P3
MINIMUM
P� ENVELOPE Q
H4 0.25H
H2 LOOSE SAND
Q
H
P5 /P4 PS P7 0.75H Hw,
SOFT /
SILT
H3
62.4H w' 30h1 Q
D
P6� P9 NOTES:
1 1. THE PRESSURE DIAGRAM RECOMMENDED FOR A
f�l MULTIPLE BRACED SYSTEM IS SEMI-EMPIRICAL.
NET PASSIVE DESIGN METHOD PROPOSED BY TERZAGHI AND
= P9 - P6 PECK SHOULD BE UTILIZED.
CANTILEVER/SINGLE BRACING 2. THE PRESSURE DIAGRAM BELOW THE BOTTOM OF THE MULTIPLE BRACING
EXCAVATION FOR A CANTILEVERED/SINGLE BRACED
SYSTEM MAY BE USED TO DETERMINE THE MINIMUM
P, = 62.4Hw PENETRATION DEPTH, D, FOR A MULTIPLE BRACED
SYSTEM.
P2= 40H I
P3= [5 x 105 - (Hi- 5) x 43] x 0.36 3. TO MINIMIZE POTENTIAL FOR PIPING, DEPTH OF
P4= P3 + 20H2 EMBEDMENT FOR 30TH SYSTEMS SHOULD BE GREATER
P5= 5 x 105 + (H l-5) x 43 + 53H 2 - 2 x 400 THAN 1.2 x Hw, WHERE Hw IS THE HEAD DIFFERENCE
P6= P5 + 40H3 BETW E SHE WATER LEVELS ON EACH SIDE OF THE
SHORP7= 15011 4
PS= 53H4 + (2 x 400)/1.5 4. ALL UNITS IN FEET AND POUNDS (ENGLISH UNITS).
P9= PS+ 40H 3
5. PASSIVE PRESSURES SHOWN ARE ALLOWABLE VALUES.
A FACTOR OF SAFETY OF 1.5 HAS BEEN INCLUDED.
H i = 15'
H2= 15' IN SECTION 1 (NORTH OF STA. 74+00)
H2= 25' IN SECTION 2 (SOUTH OF STA. 74+00)
LATERAL EARTH PRESSURES
SOUTH INTERCEPTOR FOR CANTILEVERED &
flONG%#twM PARALLEL: PHASE II MULTIPLE BRACED EXCAVATIONS
&ASSOCIAMINC. PROJECT NO.: 93093 FIGURE: 9
93093-8-004.2
NON—ROADWAY
AREAS _I ROADWAY AREAS
O 95 2 FEET
TRENCH
BACKFILL
• 90 VARIES
PIPE
PIPE VARIES
BEDDING
LEGEND
RECOMMENDED MINIMUM PERCENTAGE OF MAXIMUM DRY DENSITY,
90 WITH MODIFIED PROCTOR (ASTM D 1557) AS THE STANDARD
COMPACTION CRITERIA
SOUTH INTERCEPTOR PARALLEL: PHASE ]I FOR TRENCH BACKFILL
�ASSOCIATE SoINC. PROJECT: 93093 FIGURE: 10
93093-A-003.1
APPENDIX A
FIELD EXPLORATION
APPENDIX A
FIELD EXPLORATION
The field exploration program was performed December 6 through 8, 1993, and
consisted of a geotechnical reconnaissance, performance of 6 cone penetrometer test
(CPT) soundings, and advancement of 4 mud rotary borings. Northwest Cone
Exploration, Inc. and Gregory Drilling, Inc. provided cone penetrometer testing and
drilling services under subcontract to HWA. Borehole and CPT locations were
established in the field by Garry Struthers Associates' survey crew and plotted on the
Site and Exploration Plans (Figures 2 through 4).
Legends to the terms and symbols used on the boring and CPT sounding logs are
presented on Figures A-1, A-2, and A-11. Summary borehole logs are presented on
Figures A-3 through A-10. Logs of the CPT soundings are presented on Figures A-12
through A-17.
Cone Penetrometer Tests
The field investigation was initiated with a CPT program designed to provide an initial
overview of the subsurface soil conditions. At each test location, a four channel
electronic cone was used to record tip resistance, sleeve friction, pore pressure, and
inclination. The testing was performed in general accordance with ASTM D 3441.
The resistance to continuous penetration encountered by the cone tip and adjacent
friction sleeve exhibits high sensitivity to changes in soil type, providing data on soil
behavior type and correlated strength parameters (Robertson and Campanella, 1986).
The CPT soundings were advanced to depths ranging from about 34 to 45 feet below
the existing ground surface.
Borings
Gregory Drilling, Inc. advanced 4 borings with a truck-mounted, CME 75 drill rig
equipped with a 140-pound hammer with a trip-release mechanism for performing
Standard Penetration Tests (SPT). Due to the presence of heaving sands along the
project alignment, which makes drilling with hollow stem augers difficult, the borings
were advanced using mud rotary drilling techniques. The borings were advanced to
depths ranging from about 511/2 to 611/2 feet below the existing ground surface.
At each boring location, SPT sampling was performed using a 2-inch outside diameter
split-spoon sampler and a standard 140-pound hammer in general accordance with
ASTM D 1586. During the test, a sample is obtained by driving the sampler 18 inches
into the soil with a hammer free-falling 30 inches. The number of blows required for
each 6 inches of penetration is recorded. The Standard Penetration Resistance ("N-
93093R.DOC A-1 HONG WEST& ASSOCIATES, INC.
value") of the soil is calculated as the number of blows required for the final 12 inches
of penetration. If a total of 50 blows is recorded within a single 6 inch interval, the
test is terminated, and the blow count is recorded as 50 blows for the number of inches
of penetration. This resistance, or N-value, provides a measure of the relative density
of granular soils and the relative consistency of cohesive soils.
In addition, relatively undisturbed soil samples were obtained for consolidation and
unconfined compression testing by introducing a thin-walled sampler (Shelby tube) into
the borehole and pushing the tube into the soil mass ahead of the lead auger a distance
of about 30 inches. Shelby tube sampling was performed in general accordance with
ASTM D 1587.
The borings were drilled under the full time observation of an HWA engineer. Soil
samples obtained from the split-barrel and thin-walled samplers were classified in the
field and representative portions were placed in air tight, plastic bags to prevent
moisture loss. These soil samples were returned to our Lynnwood, Washington
laboratory for further examination and testing. In addition, pertinent information
including soil sample depths, stratigraphy, soil engineering characteristics, and
groundwater occurrence was recorded. The stratigraphic contacts shown on the
individual borehole logs represent approximate boundaries between soil types; actual
transitions may be more gradual or abrupt. The soil and groundwater conditions
depicted are only for the specific dates and locations reported, and therefore, are not
necessarily representative of other locations and times.
As stated above, the hammer used to perform SPT sampling was equipped with a
trip-release mechanism, which generally delivers a higher energy than a "standard"
hammer equipped with a rope and cathead mechanism. Based on previous studies
(Skempton, 1986), a 79 percent energy ratio should be used in interpreting the
recorded SPT blow-counts obtained with a trip hammer, instead of the 60 percent
energy ratio for a safety hammer with a rope and cathead system. As such, N-
values measured with a trip hammer should be multiplied by 1.3 to convert them to
normalized SPT N-values, or N(60).
�I
93093R.DOC A-2 HONG WEST& ASSOCIATES, INC.
LEGEND OF TERMS USED ON EXPLORATION SOIL LOGS
Soil classifications presented on the exploration soil logs are based on visual field and laboratory
observations, using ASTM D 2488. Soil descriptions are presented in the following general order:
Density/consistency, color, modifier, MAJOR CONSTITUENT, minor constituent(s), moisture content,
soil structure(s), additional remarks.
DENSITY/CONSISTENCY
Density/consistency of soils encountered in exploratory borings is usually based on the Standard
Penetration Test (SPT) N-value or "blowcount", ASTM D 1586. Using this method, the sampler is
driven 18 inches with a 140-pound hammer falling 30 inches. The SPT N-value is the number of
blows for the last 12 inches of sampler drive.
Unconfined
Granular Soil SPT Cohesive Soil SPT Compressive
Density N-value Consistency N-value Strength (tsf)
Very loose 0-4 Very soft 0 - 2 < 0.25
Loose 4- 10 Soft 2 -4 0.25 -0.5
Medium dense 10-30 Medium stiff 4 - 8 0.5 - 1.0
Dense 30-50 Stiff 8 - 15 1.0 -2.0
Very dense > 50 Very stiff 15 - 30 2.0 -4.0
Hard > 30 > 4.0
MOISTURE CONTENT MINOR CONSTITUENTS
Estimated Percentage
Dry Little perceptible moisture Trace 0-5
Damp Some perceptible moisture, Some 5 - 12
probably below optimum
Moist Probably near optimum moisture Modifier (sandy, silty, 12-30
content etc.)
Wet Much perceptible moisture, Very (plus modifier) 30 -50
probably above optimum
TERMS DESCRIBING SOIL STRUCTURES
Bedded Composed of layers thicker than 1 cm, of varying color and/or texture.
Calcareous Containing a significant amount of calcium carbonate.
Cemented Rock or soil hardened by the precipitation of a mineral cement among the grains
of the sediment.
Fissured Containing shrinkage cracks, frequently filled with fine sand or silt, usually more
or less vertical.
Indurated A rock or soil hardened or consolidated by pressure, cementation, or heat.
Interbedded Composed of alternating beds of different soil types.
Laminated Composed of thin(< 1 cm) layers of varying color and/or texture.
Poorly graded Predominantly a single grain size, or having some intermediate sizes missing
("gap" graded).
Slickensided Having previously-sheared planes of weakness that are slick and glossy in
appearance.
Well graded Having a wide range of grain sizes, with substantial amounts of intermediate
particle sizes.
rr
U
+IONGWEST
& ASSOCIATES, INC. Figure: A-1
LEGEND OF SYMBOLS USED ON EXPLORATION SOIL LOGS
GRAPHIC SYMBOLS FOR SOIL TYPES SAMPLE TYPE SYMBOLS
NON-COHESIVE SOILS (<50% passing BOREHOLE SAMPLES
No. 200 sieve)
GW well graded gravel and gravel/sand mix ® 2.0" 00 Split Spoon (SPT)
GP poorly graded gravel, gravel/sand mix I Shelby Tube
• GM silty gravel, gravel/sand/silt mix ai 3.0" OD Split Spoon with Brass Rings
GC clayey gravel, gravel/sand/clay mix a Grab Sample (cuttings)
- SW well graded sand, gravelly sand m Core Run
SP poorly graded sand, little or no fines TEST PIT SAMPLES
SM silty sand, sand/silt mix Bag (bulk sample)
SC clayey sand, sand/clay mix O Grab (small volume)
COHESIVE SOILS (>50% passing I Shelby Tube
No. 200 sieve)
ML inorganic silt and very fine sand HAND BORING SAMPLES
/111 CL inorganic, low plasticity clay Non-standard penetration
(40 lb. hammer with 12 inch drop)
1: OL organic, low plasticity clay, silt/clay mix O Grab Sample (post hole)
MH inorganic, elastic silt, silt/sand mix I Shelby Tube
CH inorganic, high plasticity clay
ROTARY BOREHOLE SAMPLES
OH organic, medium to high plasticity clay Continuous Core Sample �
Pt peat and other highly organic soil
Note. The graphic symbols used for the various soil types are based
on symbols recommended in the Unified Soil Classification
System. Graphic logs are based on subjective field identi-
fication of soils, and laboratory data where available.
GROUNDWATER MONITORING WELL SYMBOLS ATTERBERG LIMITS
entonite Seal
Grout Backfill
PL LL
e.
�d uttings Backfill or Caved Hole
'a c
�6 �6 0 - Natural Moisture Content
o 'e
�c iezometer Casing PL — Plastic Limit
c o
LL - Liquid Limit
Y Groundwater Level (noted during drilling)
i Groundwater Level (measured in piezometer
after water level stabilized)
lotted Piezometer Casing ��
U�,
and Backfill +IONGWEST
& ASSOCIATES, INC.
Figure: A-2
HONG WEST 6 ASSOCIATES , INC . BORING LOG
DRILLING COMPANY: Gregory Drilling, Inc. TOTAL DEPTH: 61.5 Feet
DRILLING METHOD: Mud Rotary SURFACE ELEVATION: 116.75' Feet
SAMPLING METHOD: SPT, SHELBY MEASURING POINT EL.: Feet
Lu
V N N U)
Z a) 3
z • Moist. Cont. W
u, in m Lu a 1 Pen.Resistance
w W W -- D J J
_ CL
; a m U (blows/foot)
d M: Z O :> J
o an a s z f (n ch c DESCRIPTION 0 20 40 60 80
0 NA 8" ACP over 4" gravel base coarse.
Medium dense, brown, silty SAND with gravel,
8/5/3 8 27 moist. Fine to coarse grained sand, little to some
2" minus subrounded gravel.
5 (Fill) ......... .
3/4/3 7 NA Soft to very soft,dark gray, SILT, wet. Trace
L
fine grained sand, some scattered organics.
2/2/1 3 38 (Overbank Flood Deposits)
1
10 -
0/0/0 0 54 AL
Medium dense, very dark gray to dark gray,
SM
IVI 3/4/7 11 25 poorly graded SAND with silt, wet. Fine to medium
AL
grained sand, trace 3/8" minus subrounded gravel,
SM trace organics, with occasional thin lenses of silt.
4/5/4 9 28 `
(Upper White River Sediments)
Loose to medium dense, very dark gray to dark
gray, silty SAND, wet. Fine to medium grained
20 sand, trace 3/8" minus subrounded gravel, trace
2/2/4 6 36 organics, with occasional thin lenses of silt.
(Upper White River Sediments)
5/6/6 12 31
25
10/11/13 24 NA
o e
e e
° e
e °
Very soft, dark gray, SILT with sand, wet. Little e e
30 fine grained sand, trace organics. ..... ..
0/0/0 0 44 0e e
(Lower White River Sediments) °
e °
°
OH Very soft, black, organic CLAY, wet. °
35 ,,,, 0.
0/0/1 1 NA e
(Lower White River Sediments) 00 0 0
T ° e
PUSH NA 58 PLI - °
- L e °
q 00000000
40 See next page for description. 000000
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated.
PROJECT: South Interceptor Parallel BORING: BH- 1
LOCATION: Station 82+14, 21' LT PROJECT NUMBER: 93093
DATE COMPLETED: December 8, 1993
LOGGED BY: S.R. Wright PAGE: 1 OF 2 Figure' A-3
HONG WEST & ASSOCIATES , INC .
BORING LOG
W U
(, rn 22
N
Z
( - z u • Moist.Cont. W
(n U) m w o a 1 Pen. Resistance
= J N 3 o Cj (blows/foot)
m J
CL >
o U) a z x Cl) (nn DESCRIPTION 0 20 40 60 80
40 0/0/0 0 50 Very soft, dark gray, SILT, wet. Trace shells.
o °
(Lower White River Sediments) °
o o
1[] e o
%ooMedium dense, very dark gray, silty SAND, wet. °
45 Fine grained sand. ° °
5/8/9 17 34 °
(Lower White River Sediments) °
0 0
e e
e o
Very soft, very dark gray, organic CLAY, wet. *900000
50 ;I 1 Trace fine grained sand.
..;...:... e o
0/0/0 0 34 00
(Lower White River Sediments) 0o e
O O
° 0,0,
e00
0. e
55 0
0/0/0 0 48 e
I I I
I�III� oo.
O
I'I�1 0 O
0 O
Loose, dark gray, silty SAND, wet. Fine grained e °
sand, trace organics, trace shells.
60 e e
...:
0/0/4 4 29
(Lower White River Sediments) ° °
Borehole terminated at a depth of 61.5 feet,
December 8, 1993.
65 ...............................
Installed 2" diameter piezometer.
70 ... ... ...;..:...;...
75
I
80
PROJECT: South Interceptor Parallel BORING: BH- 1
LOCATION: Station 82+14, 21' LT PROJECT NUMBER: 93093
DATE COMPLETED: December 8, 1993
LOGGED BY: S.R. Wright PAGE: 2 OF 2
Figure: A4
HONG WEST & ASSOCIATES , INC . BORING LOG
DRILLING COMPANY: Gregory Drilling, Inc. TOTAL DEPTH: 61.5 Feet
DRILLING METHOD: Mud Rotary SURFACE ELEVATION: 117.50' Feet
SAMPLING METHOD: SPT, SHELBY MEASURING POINT EL.: Feet
W U
Z 3
O
v L) In z • Moist.Cont. W
Cn
cn V') m ui U a I Pen.Resistance
= J Cr N J F- O U
0
a J (blows/foot)
o Lu Cn a Z' x: (ni ccn DESCRIPTION
0 20 40 80 80
0 NA 6" ACP over 3" gravel base coarse.
SM Medium dense, brown, silty SAND with gravel,
moist. Fine to coarse grained sand, little r' minus
8/8/5 13 17 subrounded gravel. �I►
5 (Fill) .. .. ... ...
4/4/8 12 14 Medium dense, dark grayish brown, silty SAND,
moist to wet. Fine to medium grained sand.
5/4/5 9 18 •
(Overbank Flood Deposits?) i
10 Becoming dark gray and very loose.
0/1-12" 1 28 4
Very soft, dark grayish brown, organic SILT to
15
sandy SILT with organics, wet.
0/0/0 0 45
(Upper White River Sediments?)
Medium dense, very dark gray, poorly graded
SM
20 SAND with silt, wet. Fine to medium grained sand,
occasional lenses of silt, trace organics.
...........
8/10/8 18 20 r
(Upper White River Sediments)
SM Medium dense, very dark gray, silty SAND, wet.
25 Fine to medium grained sand, occasional lenses of
5I5/1 12 31 silt, trace organics.
(Upper White River Sediments) 0°
000000
000600*0
Very soft, dark gray to very dark gray, SILT, e
0.0.00
30 wet. Trace fine grained sand, trace organics, °
06
0/0/I I 44 trace shells. � e °
(Lower White River Sediments) °
000000
I PUSH NA 31 0
e 00 0o
0 0
e e
35 ... ...;....... 0
e e
0/0/0 0 57 °
e e
o e
e
°000000 o
e
° °
40 ° °
NOTE: This log of subsurface conditions applies only at the specified location and on the date Indicated.
PROJECT: South Interceptor Parallel BORING: BH-2
LOCATION: Station 80+08, 21.5' RT PROJECT NUMBER: 93093
DATE COMPLETED: December 8, 1993
LOGGED BY: S.R. Wright PAGE: 1 OF 2 Figure: A-5
HONG WEST & ASSOCIATES , INC .
BORING LOG
LLJ U
U H
Z y ;
v g z u • Moist.Cont. W
w w m Uj 0 J J 1 Pen. Resistance
= J CrN J O L) (blows/foot)
Q m J
Z > X
LLI o U) a Z' x ai ai DESCRIPTION 0 20 40 60 80
40 Very soft, dark gray to very dark gray, SILT, °
0/0/0 0 48 wet. Trace fine grained sand, trace organics, °
0 0
trace shells. ° °
0*000oe
(Lower White River Sediments) °
e e
45 Medium dense, very dark gray, silty SAND, wet.
3/8/12 20 34 Fine grained sand, trace organics.
e e
e e
(Lower White River Sediments) e e
° e
Very soft, very dark gray, organic CLAY, wet. °
e o e
Trace shells. e °
0/0/0 0 40 ;;;�; ♦ e e
(Lower White River Sediments)
e e
e °
t o o
55 ° e
...:...:...
0/0/0 0 45
o e
Loose, dark gray, silty SAND, wet. Trace shells.
60 ° o
...:.. ...:...:.. . e e
5/3/5 8 28 (Lower White River Sediments)
e e
Borehole terminated at a depth of 61.5 feet,
December 8, 1993.
Installed 2" diameter piezometer.
70 ...:...:..........
75 ....:....:...
80
PROJECT: South Interceptor Parallel BORING: BH-2
LOCATION: Station 80+08, 21.5' RT PROJECT NUMBER: 93093
DATE COMPLETED: December 8, 1993
LOGGED BY: S.R. Wright PAGE: 2 OF 2 Figure' A-6
HONG WEST & ASSOCIATES , INC . BORING LOG
DRILLING COMPANY: Gregory Drilling, Inc. TOTAL DEPTH: 61.5 Feet
DRILLING METHOD: Mud Rotary SURFACE ELEVATION: 117.2' Feet
SAMPLING METHOD: SPT, SHELBY MEASURING POINT EL.: Feet
W U
L) N 2C U)
Z y 3
0
U a z U Moist.Cont. M
u, u, CD w L a 1 Pen.Resistance
S J rL
03
� Z o < N J (blocs/foot)
o uai a z W Cnn DESCRIPTION
0 0 20 40 60 80
NA 6" ACP over 4" gravel base coarse.
Medium dense,brown, silty SAND with gravel,
moist. Fine to coarse grained sand, little to some
2" minus subrounded gravel.
5— (Fill)
0/0/0 0 45 Very soft, dark gray, SILT, moist to wet.
Occasional lenses of fine sand, trace to little
1/1/1 2 42 organics.
(Overbank Flood Deposits) i
10
0/0/0 0 61 i
Very loose,very dark gray, silty SAND, wet. Fine
15 grained sand, occasional 2" thick interbeds of
1/1/1 2 80 peat and silt. lip
(Overbank Flood Deposits?)
SM Medium dense, very dark gray, silty SAND, wet.
20 Fine to medium grained sand, with thin lenses of
:...:..
5/5/8 11 34 silt.
(Upper White River Sediments)
25
5/8/12 20 28 e e
o °
e e
Medium dense, very dark gray, poorly gradedSM
e °
30 SAND with silt, wet. Fine to medium grained sand, e e
7/9/11 20 28 with thin lenses of silt. e °
e e
(Upper White River Sediments) e 0.0.00.0.0
o
o e
° o
e e
35 :. .:...;... .. e e
8/13/12 25 30 Trace organics.
o o °
e °
o °
°
ML Very soft, very dark gray, SILT, wet. (Lower q
40 White River Sediments)
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated.
PROJECT: South Interceptor Parallel BORING: BH-3
LOCATION: Station 74+19, 0.4' RT PROJECT NUMBER: 93093
DATE COMPLETED: December 7, 1993
LOGGED BY: S.R. Wright PAGE: 1 OF 2
Figure: A-7
i
HONG WEST & ASSOC I ATES , INC .
BORING LOG
W U
U H U)
z y Z
O
z C6 • Moist.Cont. M
Cn Cn co U a I Pen.Resistance
2 J ¢ tO J H O U
(blows/foot)
F a 3 Q N m
� J
a Z O � f
LLJ
o vai a z s >U-) U) DESCRIPTION 0 20 40 60 80
40 ML Very soft, very dark gray, SILT, wet.
0/0/0 0 NA °
(Lower White River Sediments) e
I PUSH NA 41
PL�L
°
45 pl Stiff, dark gray, sandy SILT, wet. Trace fine ° °°
8/7/6 13 31 grained sand, trace organics. J *
.0000000
(Lower White River Sediments) °
Very soft, very dark gray, organic CLAY, wet. ° °
o 0
50o.1/1-12" 1 48 (Lower White River Sediments) °° o
°
° °
, ° °
° °
Very soft, dark gray, sandy SILT, wet. Some fine ° °
55 grained sand. ° °
0/1-17' o
I 30 (Lower White River Sediments)
° o °
°
Dense, very dark gray, silty SAND, wet. Fine
60 grained sand. ° °
12/15/16 31 27 y °
(Cedar River Deltaic Deposits)
Borehole terminated at a depth of 61.5 feet,
December 7, 1993.
65
Installed 3/4" diameter piezometer.
70 ............
75
80
PROJECT: South Interceptor Parallel BORING: BH-3
LOCATION: Station 74+19, 0.4' RT PROJECT NUMBER: 93093
DATE COMPLETED: December 7, 1993
LOGGED BY: S.R. Wright PAGE: 2 OF 2
Figure: A-8
HONG WEST & ASSOCIATES , INC . BORING LOG
DRILLING COMPANY: Gregory Drilling, Inc. TOTAL DEPTH: 51.5 Feet
DRILLING METHOD: Mud Rotary SURFACE ELEVATION: 116.84' Feet
SAMPLING METHOD: SPT, SHELBY MEASURING POINT EL.: Feet
uJ U
U H aC U)
Z 3
< t O
z u Moist.Cont. M
Cn m w o c l Pen.Resistance
2 J ¢ ' J O U
(blows/foot)
� CL 3 Q � m J
d 2 Z O > 2:
o W a z � (n U) DESCRIPTION
0 0 20 40 60 80
NA g ACP over 5" gravel base coarse.
Medium dense, brown, silty SAND with gravel,
moist. Fine to coarse grained sand, little to some
2/2/1 3 23 2" minus subrounded gravel.
5 (Fill) ... ...
2!1/1 2 29 Soft, dark gray, SILT with sand to sandy SILT,
moist to wet. Fine to coarse grained sand, trace
1/I/1 2 21 to little 1/2"minus subrounded gravel.
(Overbank Flood Deposits)
1
2/2/2 4 26
Medium dense, very dark gray, poorly graded
i5 SAND with silt, wet. Fine grained sand.
......
....
3/4/7 11 28 �
(Upper White River Sediments)
Medium stiff, very dark gray, SILT, wet. Trace
20 fine grained sand, trace organics.
2/2/5 7 38
(Upper White River Sediments) L
Medium dense, very dark gray to dark gray,
SM 25 poorly graded SAND with silt, wet. Fine to medium
IV grained sand, trace 3/8" minus subrounded
5/9/13 22 25 : M: , ,:
gravel.
00000000
(Upper White River Sediments) °
° °
° °
30 ° °
........
8/12/14 26 24 ° °
° °
°
o
° °
o
35 ... ...:.........
° °
6/12/13 25 27 °
° 0 °
° °
00000000
° °
Very soft, dark gray, lean CLAY, wet. Trace fine ° o66o
40 grained sand. (Lower White River Sediments) °
NOTE: This log of subsurface conditions applies only at the specified location and on the date Indicated.
PROJECT: South Interceptor Parallel BORING: BH-4
LOCATION: Station 64+42, 0.4' LT PROJECT NUMBER: 93093
DATE COMPLETED: December 7, 1993
LOGGED BY: S.R. Wright PAGE: 1 OF 2 Figure: A-9
I
HONG WEST & ASSOCIATES , INC .
BORING LOG
W in
U m M �
Z i
Q t O
w �, z • Moist.Cont. M
U) U) m W U Q I Pen.Resistance
2 ¢ '^ r O U
Z o M J (blows/foot)
LU o ai a z f Cn Ln DESCRIPTION 0 20 40 60 80
40 1/1/1 2 45 See previous page for description.
° 0 °
' OL Very soft, very dark gray, organic CLAY, wet.
I PUSH NA 48 : PILL 0° °
(Lower White River Sediments) o 0
0000000
45 Very soft, dark gray, sandy SILT, wet. Some fine .. ........• °
0/0/0 0 o
38 grained sand,trace organics, trace shells. .00o oe
° °
(Lower White River Sediments) °
000000oo
Medium dense, dark gray, silty SAND, wet. Some
50 fine grained sand, trace organics, trace shells.
3/5/5 10 28 °
(Cedar River Deltaic Deposits) °
Borehole terminated at a depth of 51.5 feet,
December 7, 1993.
Installed 3/4" diameter piezometer.
60 .......:...:...
65
70 ............ ........... ...
75 ... ...�...........
80
PROJECT: South Interceptor Parallel BORING: BH-4
LOCATION: Station 64+42, 0.4' LT PROJECT NUMBER: 93093
DATE COMPLETED: December 7, 1993
LOGGED BY: S.R. Wright PAGE: 2 OF 2 Figure: A-10
HONG WEST & ASSOCIATES , INC . BORING LOG
DRILLING COMPANY: TOTAL DEPTH: Feet
DRILLING METHOD: SURFACE ELEVATION: Feet
SAMPLING METHOD: MEASURING POINT EL.: Feet
in
w _ Z' g 0
� O
z Moist.Cont. W
�- cn in CD w o a l Pen.Resistance
S J 'r H J F.: O U
LU
(blows/foot)
a (n m J
a x Z o >
LU
o can Lou z a uri ch DESCRIPTION 0 20 40 60 80
0 {�
f4 Organic Material (soil behavior type 2)
Lean Clay (soil behavior type 3).
Silt to Lean Clay (soil behavior type 4).
Silt to Sandy Silt (soil behavior type 5).
Silty Sand to Sandy Silt (soil behavior type 6).
Silty Sand (soil behavior type 7).
Sand with Silt to Silty Sand (soil behavior type
5 8) :...:...
Sand to Sand with Silt (soil behavior type 9).
Soil behavior types determined using
Robertson and Campanella, 1988.
Water level estimated from CPTu test results.
10
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated.
PROJECT: South Interceptor Parallel BORING: LEGEND
LOCATION: Renton, Washington PROJECT NUMBER: 93093
DATE COMPLETED:
LOGGED BY: PAGE: 1 OF 1
Figure: A-11
Cone Penetration Test - CPT 1
CPT Tat :CPTI
Teat Date:06 Dec 1993 Page 1 of 1 Ground Surf.Elev.:118 R
Operaw:Northwest Cam Exploration Water Table Depth :9.5 R
L)I-Sdm :METRO South Iaarccptor Parallel:Phase U
0c (tsf) PWP (tsf) Friction (tsf) Bq Fr. Ratio M N60
0 50 100 150 200 250-1 -.4 .2 .8 1.4 2 0 1 2 3 4 5 -.5 -.25 0 .25 .5 0 2 4 6 6 10 0 8 15 24 32 40
0 0
5 5
10 f0
15 15
w
w
m
m 20 20
c
Inn >`
G
25 n 25
0
LN '.
(9 L '.
L '.
N
D (n •
4130 30
11
L L
N L
w
y
0 M •
35 35
40 40
45 45
50 Qc normalized for 50 Bq=dU/(Qc-ov) Pr Ratio=100'P/(Qc-0v)
►.� unequal wW area effects Gamma—110 pcf Gamma 110 pcf
lam+
N
PROJECT NO.93093 DATE: 13 Dec 1993 DRAWN BY:K.R.Brown Hong West& Associates Inc.
Cone Penetration Test - CPT2
CPT Teat :CPT2 117 1t
Teat Dots:06 Dec 1993 Page I of 1 Ground Surf.Elev.
Operator:Northwest Cone Exploration Water Table Depth 9.5 R
Location :METRO South Interceptor Parallel:Phase 11
Oc (tsf) PWP (tsf) Friction (tsf) Bq Fr. Ratio M N60
0 50 100 '150 200 250-1 -.4 .2 .B 1.4 2 0 t 2 3 4 5 -.5 -.25 0 .25 .5 0 2 4 6 B 10 0 8 16 24 32 40
O O
5 5
10 to -eT 1 �1 I I
15 19
w
m 20 20
w
L
T
N C
O L
7 25 25
o
L ~
O L
J
D U)
m 30 w 30
L
L
L y
Y ,ti
6 C
O
35 eO 35
40
40
Sir-
45
45
50 50
o
B4=dU/(Qc- v) Pr Ratio= 100'P/(QriOV)
Qc normalized for� unequal and area effects m Gama-110 pcf Gaming '110 pot
W
PROJECT NO.93093 DATE: 13 Der 1993 DRAWN BY:K.R.Brown Hong West&Associates Inc.
Cone Penetration Test - CPT3
CPT Test :CP73
Test Date:06 Doc 1993 Page I of 1 Oround Surf.Elev.: 117 R
Opa m:Northwest Cow Ssplorattom Wster Table Depth 9 R
Location :MI'1'RO South Imteceeptw Parallel:Phase B
Oc (tsf) PWP (tsf) Friction (tsf) Bq Fr. Ratio M N60
0 50 100 150 200 250-1 -.4 .2 .6 1.4 2 0 1 2 3 4 5 -.5 -.25 0 .25 .5 0 2 4 6 a 10 0 B 16 24 32 40
p 4 0
f1
C CI
5 5
10 10
15 15
u
0
m 2p 20
L r
N � .
Q
25
o 0 25
L q
c '
z �
o
m3p 30
c
c ,
n c '
oh+
35 35
40 40 -CI La
45 45
r•
50 Qc normalized for 50 Bq=dIJ/(Qc-ov) Pr Rado=100'P/(Qc-ov)
fD unequal end area effeM Gamma- 110 pcf Gamma-110 pcf
Mom+
PROJECT NO.93093 DATE: 13 Dec 1993 DRAWN BY:K.R.Browm Hong West& Associates Inc.
Cone Penetration Test - CPT4
CPT Tat :CPT4
Teat Date.06 Dec 1993 Page 1 of l around Surf.Hev.: I18 R
Operator:Northwest Cone Exploradm Water Table Depth 10 ft
l.omdon :METRO South Interceptor Parallel:Pbme B
Oc (tsf) PWP (tsf) Friction (tsf) Bq Fr. Ratio M N60
0 50 100 150 200 250-1 -.4 .2 .8 1.4 2 0 1 2 3 4 5 -.5 -.25 0 .25 .5 0 2 4 6 B 10 0 8 16 24 32 40
0 0
5 5
f0 10
f5 15
N
u
W 20 20
L
T
D IL
325 0 . 25
0
z
o to
m30 d 30
L
t L
u
a
O M
35 35
40 40
45 45
oil
QQ�
50 Qc normalized for 50 Bq=dU/(Qc-ov) Pr Ratio=100*P/(Qc-ov)
unequal end area effects Gamma-Ito pcf Gamma.— 110 pcf
eo
LA
PROJECT NO.93093 DATE: 13 Dec 1993 DRAWN BY:K.R.Brown Hong West& Associates Inc.
Cone Penetration Test - CPT5
CPT Test :CPTS
Test Data:06 Dec 1993 Page 1 of 1 Oround Surf.mov.: 117 1t
Operator:Northwest Cone Exploration Wear Table Depth : 9 ft
Locatlou :METRO South Interceptor Parallel:Phase II
Oc (tsf) PWP (tsf) Friction (tsf) Sq Fr. Ratio M N60
0 50 100 150 200 250-1 -.4 .2 .8 1.4 2 0 1 2 3 4 5 -.5 -.25 0 .25 .5 0 2 4 6 8 10 0 e 16 24 32 40
0 0
5 5
10 10
15 15
u
w 20 20
L T
N C
[S
D W
3 25 0 25
o
to L
L al
2
O N
m30 1030
L L
N e,
CI
O ~
95 35
40 40
45 45
oil
SO normalized for 50 Bq=dU!(Qc-ov) Pr Ratio= IOOeP/(Qc ov)
unequal and area effects Gamma-110 pcf Gamma=110 pcf
fD
1
r
o�
PROJECT NO.93093 DATE: 13 Dec 1993 DRAWN BY:K.R.Brown Hong West& Associates Inc.
Cone Penetration Test - CPT6
CPT Teat :CPT6
Teat Date:06 Dec 1993 Page 1 of 1 Ground Surf.Elev.:117 ft
Operator:Northwest Cone Exploration Water Table Depth 9 ft
Locatkm :METRO South fntareptor Parallel:Phase II
0c (tsf) PWP (tsf) Friction (tsf) Bq Fr. Ratio W N60
0 50 100 150 200 250-1 -.4 .2 .8 1.4 2 0 1 2 3 4 5 -.5 -.25 0 .25 .5 0 2 4 5 B 10 0 6 16 24 32 40
0 0
5 -- -- 5
4
so 4f 10
z z
15 15
m
m 20 20
L
7 T
(n L
Q •
D
3 25 a ' 25
� L
3 L
o
m 30 - 3o
L
L L
N N
C
O
35 35
40 40
45 45
Oil L
ram.
50 50
Qc normalized for Bq=dU/(QC-ov) Pr Ratio=100'P/(Qc-w)
r 1 unequal and area effects Gamma-I10 pcf Gamma 110 pcf
fD
t
4
PROJECT NO.93093 DATE: 13 Dec 1993 DRAWN BY:K.R.Brown Hong West & Associates Inc.
APPENDIX B
LABORATORY TESTING
APPENDIX B
LABORATORY TESTING
Representative soil samples recovered from the borings were returned to the HWA
laboratory for further examination and testing. Selected soil samples were used for
determination of index properties and characterization of engineering parameters.
Laboratory tests, as described below, included determination of moisture content,
Atterberg Limits, and grain size distribution. One-dimension consolidation and
unconfined compression tests were also performed.
Moisture Content Testing
The moisture content of all recovered samples was determined in general accordance
with ASTM D 2216. The test results are shown on the appropriate boring logs,
Appendix A.
Atterberg Limits Testing
The liquid limit (LL), plastic limit (PL), and plasticity index (PI) of several selected
samples were determined in general accordance with ASTM D 4318. The tests were
conducted on selected fine-grained soil samples for classification, and to aid in
estimating soil compressibility and shear strength using empirical correlations. The test
results are summarized below and are shown on the appropriate boring logs.
Table B-1.
Summary of Atterberg Limits Test Results
Depth Soil
Boring (feet) LL I PL PI Classification
BH-1 36'/2 - 38'/z 56 28 28 OH
BH-3 42 - 44 38 25 13 ML
=B�-� 42 - 44 44 25 19 OL
Grain Size Distribution
The grain size distributions of selected soil samples were determined in general
accordance with ASTM D 422. Grain size distribution curves for the tested samples
are presented on Figures B-1 through B-4. Several samples were washed on the U.S.
93093R.DOC B-1 HONG WEST& ASSOCIATES, INC.
Standard No. 200 sieve to determine the percentage of fines. Table B-2 summarizes
the test results.
Table B-2.
Percent Passing U.S. No. 200 Sieve Test Results
Percent Passing
Sample Depth U.S. No. 200
Boring (feet) Sieve
BH-1 71/2 - 9 90
BH-1 16 - 171/2 45
BH-1 20 - 211/2 47
BH-1 231/2 - 25 24
BH-2 5 - 61/2 22
BH-2 71/2 - 9 24
BH-2 10 - 111/2 23
BH-2 20 - 211/2 10
BH-2 32 - 34 86
BH-3 20 - 211/2 25
BH-3 25 - 261/2 17
BH-4 15 - 161/2 13
BH-4 20 -211/2 84
Consolidation Testing
One-dimensional consolidation tests were conducted on several relatively undisturbed
soil samples extruded from the recovered Shelby tubes. The testing was conducted in
general accordance with ASTM D 2435, using a fixed-ring consolidometer. The
primary purpose of the consolidation test is to aid in the estimation of potential
consolidation and secondary settlement characteristics of a soil upon placement of
additional loads. The test results are presented on Figures B-5 and B-6.
Unconfined Compressive Strength Testing
Unconfined compressive strength tests were conducted on several relatively undisturbed
samples extruded from the recovered Shelby tubes. The testing was conducted in
general accordance with ASTM D 2166, using strain-controlled application of the axial
load. The test results provide an approximate value of the strength of cohesive soils in
terms of total stresses. The test results are presented on Figures B-7 through B-10.
93093R.DOC B-2 HONG WEST& ASSOCIATES, INC.
HONG WEST & ASSOCIATES, INC.
. GRAIN SIZE DISTRIBUTION
Project: METRO South Interceptor, Station 82+14 Test Hole Number: BH-1
---------------------------------------------------------------------------------------
------------------------------
------------------- Renton,--Washington- - - --------------------------------------------- Sample Number: S—5
- - - - ---------------
Project Number: 93093 Depth: 13.5-15.0 feet
-------------------------------------- p
---------------------------------------------------
Date Tested: 12-23-93 Sample Description:
-------------------------------------------------------------
Remarks: ------Dark...Bray, poorly graded SAND-------------------- Gravel: 0.0__ ---
-------------------------with_-silt- (SP—SM� ----------------------- Sand: ------------88.9
-- SP------- --------------------- -----------------------------
Fines: 11.1
---------------------------------------------------------------------------------------------------- ---------------------------------------------
Clay Silt Sand Gravel
Fine Medium Crse Fine Crse
SIEVE SIZES
100
200 100 60 40 30 20 16 10 4 3/8 3/4 1 3/2 2 3
I 1 I I I I I I I I
I i I I I I I I I
90 —————— ——— —————————————— ——J— —L———J—1—I—— —— —— —— —
I I I I I I I I I I
1 I I I I I I I I I
I I I I I --80 —————— ————————————————— I I I I I 1I I
—
I I
I 1 I I I I I I I 1
I I 1 I I I I 1 I I
J I 1 I I I I I I I I
Q 60 —————— ————————————————— ——J--L --J-1-1-- ———— --1--- - 1-1-1--
I I I I I 1 I I 1 I
V)
50 ------ - ---------------- —_
-
I 1 I I I I I I
W I I I I I I 1 I I I
CU40 ------ ----------------- --- r---1—r- -- ---- ---t -I— -- t— t—I--
� I I I I I I
W
W
30 —————— ———— ————————————— ——J —L———J—1—1—— —— —— ——1 —
I I I 1 1 I I I I I I
I I I I I I I I I I
20 I 1 1 1 -- I —I- - - I I
______ ____ _____________ _ _
I I 1 I 1 I I I I I
I I I 1 I I I I
I I I I 1 1 I I I I
I I I I 1 I I I I I
0
5 2 5 2 5 2 5 2 5 2 5
0.001 0.01 0.1 1 10
GRAIN SIZE — MILLIMETERS
Figure: B-1
HONG WEST & ASSOCIATES, INC.
. GRAIN SIZE DISTRIBUTION
Project: METRO South Interceptor, Station 80+08 Test Hole Number: BH-2
--------------------------------------------------------------------------------------- ------------------------------
Renton, Washington Sample Number: S-7
- ---------- -- ---------------------------------------------------- ---------------------------------
Project Number: 93093 Depth: 25.0-26.0 feet
---------------------------------------------------------------------- ---------------------------------------------------
Date Tested: 12-23-93 Sample Description:
---------------------------
Remarks: Dark gray,__silty SAND_ (SM)_ _ Gravel: 0.0
-------------
Sand: 76.6
---------------------------------------------------------------------------------------------------- -------------------------------------------
__-_-__-_- Fines: 23.4
- - ------------------------------------------------------------------------------------------- -------------------------------------------
Clay Silt Sand Gravel
Fine Medium Crse Fine Crse
SIEVE SIZES
100
00 200 100 60 40 30 20 16 10 4 3/8 3/4 1 3/2 2 3
I I I I I I I I I I
I I I I I I I I I I
90 —————— —————————————— ——— ——J——L ——J—1—I—— ———— —— 1 —�— —
I I I I I 1 I I I I
80 —_ I—_ I I I I I I
______ _________________ _
I I I I I I 1 I I I
I I I I I 1 I I I
W
—————— —————————— ———————0 __1_ Y___-i_t._f—_ ____ __- _I___t_t_1__
J I I I I I i I I I I
J 1 I I 1 I I I I I I
Q 60 —————— ————————————————— --J--L---J-1—L— ———— --1 -1--- 1-1—I--
I
N I I I I I I I I I
H 50 ' —'---'—'—'-- I I I I
------ -----------------
z I 1 I I I
UI I I I I 1 I I
W I I I I I I I I I I I
O_ 30 _ _1
—————— ——————— —————————— —J——L———J—1—1—— ——— —
I I I I I 1 I I I
I I I I I 1 I I I I
20 I I I I
I I I I I 1 I I I I
I I I I I I I I I I
10 ______ _ _ __ _ _ _ __________ __y __ __ __ .�
I I I I I I I 1 I I
I I I I I I I I I I
0
5 2 5 2 5 2 5 2 5 2 5
0.001 0.01 0.1 1 10
GRAIN SIZE — MILLIMETERS
Figure: B
1
HONG WEST & ASSOCIATES, INC.
. GRAIN SIZE DISTRIBUTION
Project: METRO South Interceptor, Station 74+19 Test Hole Number: BH-3
--- ----------------------------------------------------------------------' ------------------------------
Renton, Washington Sample Number: S-8
---------------------------------------------------------------------------------------------------- ---------------------------------
Project Number: 93093 Depth: 30.0-31 .5 feet
---------------------------------------------------------------------- ---------------------------------------------------
Date Tested: 12-23-93 Sample Description:
------------------------------------------------------------------------------
Remarks: _ Dark... ray, poorly graded SAND Gravel: 1 .5
----------------------- -----------------------------------------
with silt (SP—SM� Sand: 90.5
--SP---S -------------------------------------------- - -----------------------
------------ -------------------------------------------------------------------------------------- Fines: 8.0
---------------------------------------------------------------------------------------------------- ---------------------------------------------
Clay Silt Sand Gravel
Fine Medium Cne Fine Crse
SIEVE SIZES
O 0 200 100 60 40 30 20 16 10 4 3 8 3/4 1 3/2 2 3
I I I I I I I I I I
I I I I I I I I I
90 ------ ----------------- -- J- -L ----� -I-- - --- --J-1---1-1-I--
I I I I I I I I I I
I 1 I I I 1 I I 1
___ ___ __________ ____
I - I --- I- -I- I I I I I
I I I I I I I I I I
I I I I I I I I I I
LLJ70 ------ ----------------- --1-- -
J I I I I I I I 1 1 I
Q ------ ----------------- --J ----L---J-L-1 -I---1-1-I- -
60 I I I I I ____ -- I i I
V) I I I I I I
F- 50 1 I I I I I I I I
------ --- --------------
I I I I I I I I I I
Z I I I I I I I I I I
W I I I I I I I I
40 ------ --- ----------- --- --1- -r--- ,-+---- ---- -----I---t-t-I- -
W I I 1 I I I I I I I
I a_ 30 —————— ——— — ——————— —————— ——J—— ---J-1-1-- --J—I---1-1-1--
I I I I I I I
I I I I I I I I I I
20 i I I I I I I I
__ ____ ________ _____ ___
1 I I I I I I I I I
I I I 1 I I I I I I
I I I I I I I I I
10 ______ _____ ___ _ _______ _
I I I I I i 1 I I I
I I I I I I 1 I 1 I
0
5 2 5 2 5 2 5 2 5 2 5
0.001 0.01 0.1 1 10
GRAIN SIZE - MILLIMETERS
Figure: B-3
HONG WEST & ASSOCIATES, INC . -
. GRAIN SIZE DISTRIBUTION
Project: METRO South Interceptor, Station 64+42 Test Hole Number: BH-4
--------------------------------------------------------------------------------------- ------------------------------
Renton, Washington Sample Number: S-7
---------------------------------------------------------------------------------------------------- ---------------------------------
Project Number: 93093 Depth: 25.0-26.5 feet
---------------------------------------------------------------------- ---------------------------------------------------
Date Tested: 12-23-93 Sample Description:
Remarks: ____Dark_ gray, poorly graded SAND Gravel: 0:4
_________________________with silt (SP-SM) Sand: 92.9
- ---------- ----------- -------------------------------------------- -------------------------------------------
Fines: 6.7
---------------------------------------------------------------------------------------------------- ---------------------------------------------
Clay Silt Sand Gravel
Fine Medium LTFine Crse
SIEVE SIZES
200 100 60 40 30 20 16 10 4 3 8 3/4 1 3/2 2 3
100
1 I I I I I I I I I i I
I I 1 I I —— —— --
I I I I I
90 J--L �—� —I1—I---1-1—I--
------ ----- - -- ------- -- -- ——— —
I I I I 1 I I I I I
I I I I I I I I I I i
80 __ ___ I — I — I
I I I I I I I I
I I I I I I 1 I I I
wI I I I I I I I I 70 ------ --------------- -- ---- ---- -+—I-- -- -- -- + -I---t-t-1- -
J
Q ---- —J--L— J—L—I-- ———— -- 1—I---1-1—I--
60 ————— — —————————— — I I I I I I
N I I I I I I I I I I
H 50 ------ ----------------- I -- I -1- -- I I I
-
I
I I I I I I I I I
------ ---- -
W
CL I I I I I I I 1 I
30 —————— —— — — —— ——————————— ——J—— ---J—L—I-- -- 1 —I— --1-1-1--
I I I I I I I 1 I
I I 1 I I I I I I I
I I I I t I I I I
______ ________________ _ _
Q —___ _ __ _ _ ___ _I___—___I_
I I I I I I I I I I
I I I I I I I
I I I I I I I I 1 I
I I I i I I I I I I
0
5 2 5 2 5 2 5 2 5 2 5
0.001 0.01 0.1 1 10
GRAIN SIZE — MILLIMETERS
Figure: B-
HONG WEST & ASSOCIATES, INC.
Consolidation Test Results
Project: South Interceptor Porollel: Phose 11 Test No. 1
Location: Renton, Washington Boring: BH-1, S-11
Depth (ft.): 36.5-38.5
Project Number: 93093 Diameter (in.): 2.5
Date Tested: 12-20-93 Assumed Sp. Gravity. 2.65
1.4
1.3
1.2
0
a
o'
>° 1,1
1.0
0.9
0.1 1 10 100
Pressure (ksf)
INITIAL FINAL
Height (in.) 1.0 0.819 Sample Description: Dark gray,
Water Content % 49.1 37.0 Organic Clay (OH)
Wet Density (pcf) 103.7 95.2
Dry Density (pcf) 69.6 69.6 Liquid Limit: 55.9
Saturation % 94.5 100 Plastic Limit: 27.8
93093-A-001.2
Figure: B-5
HONG WEST & ASSOCIATES, INC. I
Consolidation Test Results
II
Project: South Interceptor Parollel: Phase II Test No. 2
Location: Renton, Washington Boring: BH-4, S-10A
Depth (ft.): 42-44 I
Project Number: 93093 Diameter (in.): 2.5
Date Tested: 12-22-93 Assumed Sp. Gravity. 2.7
1,4
I
1,3
I
°' 1.2
0
0
o' I
> 1,1
I
1.0 I
I
0.9
0.1 1 10 100
Pressure (ksf) I
INITIAL FINAL
Height (in.) 1.0 0.8661 Sample Description: Gray, Organic
Water Content % 44.8 37.5 Clay (OL)
Wet Density (pcf) 106.4 116.7 I
Dry Density (pcf) 73.5 84.9 Liquid Limit: 44.3
Saturation % 99.7 100 Plastic Limit: 24.6
93093-A-002.1
Figure: B-6
UNCONFINED COMPRESSION TEST
PROJECT: METRO-South Interceptor
PROJECT No.: 93093 DATE: 12-21-1993
2.5
0.5
0.00% 5.00% 10.00% 15.00% 20.00%
PERCENT STRAIN
Sample No.: S-11 A Test Type: Un. Com
Sample Location: BH-1 Sample Length (in): 5.5
Depth(ft): 36.5-38.5 Sample Diameter (in): 2.8
Soil Classification: OH Peak Stress (ksf): 1.07
Moisture Content(%): 54.1
Dry Density(pcf): 68.7 I
Liquid Limit(%): 55.9 Failure Mode:
Plastic Limit(%): 27.8
GO
iHONGWEST
&ASSOCIATES.INC. Figure: B-7
UNCONFINED COMPRESSION TEST
PROJECT: METRO-South Interceptor
PROJECT No.: 93093 DATE: 12-21-1993
2.5
1.5
w -- --` . _ - --- --- ---- - - -- ...... -
i
1
0.00% 5.00% 10.00% 15.00% 20.00%
PERCENT STRAIN
Sample No.: S-8a Test Type: Un. Com
Sample Location: BH-2 Sample Length (in): 5.5
Depth(ft): 32-34 Sample Diameter (in): 2.8
Soil Classification: SM Peak Stress (ksf): 0.81
Moisture Content(%): 31.5
Dry Density(pcf): 89.4
Liquid Limit(%): N/A Failure Mode:
Plastic Limit(%): N/A
GO
+LONG WEST
&ASSOCIATES•INC. Figure: B-8
UNCONFINED COMPRESSION TEST
PROJECT: METRO-South Interceptor
PROJECT No.: 93093 DATE: 12-21-1993
2.5'-
2
1.5 -
V)
Cn
0.5
0
0.00% 5.00% 10.00% 15.00% 20.00%
PERCENT STRAIN
Sample No.: S-10a Test Type: Un. Com
Sample Location: BH-3 Sample Length (in): 5.5
Depth(ft): 42-44 Sample Diameter (in): 2.8
Soil Classification: ML Peak Stress (ksf): 1.58
Moisture Content(%): 43.6
Dry Density(pcf): 78.3
Liquid Limit(%): 37.6 Failure Mode:
Plastic Limit(%): 25.3
GO
+IONGWEST
& ASSOCIATES,INC. Figure• B-9
UNCONFINED COMPRESSION TEST
PROJECT: METRO-South Interceptor
PROJECT No.: 93093 DATE: 12-21-1993
2.5 -
2 -
Ln
...............
Cn
.........
A
0.5
0.00% 5.00% 10.00% 15.00% 20.00%
PERCENT STRAIN
Sample No.: S-10a Test Type: Un. Com
Sample Location: BH-4 Sample Length (in): 5.5
Depth(ft): 42-44 Sample Diameter (in): 2.8
Soil Classification: OL Peak Stress (ksf): 1.71
Moisture Content(%): 44.8
Dry Density(pcf): 77
Liquid Limit(%): 44.3 Failure Mode:
Plastic Limit(%): 24.6 N
G
+IONGWEST
&ASSOCIATES,INC. Figure• B-10