HomeMy WebLinkAboutSWP2703061_3HWAutOSCIENCES INC.
GEOTECHNICAL REPORT
SW 27TH STREET CULVERT REPLACEMENT
RENTON, WASHINGTON
HWA Project No. 98032
October 26, 1998
Revised March 19, 1999
Prepared for:
R. W. BECK
1001 Fourth Avenue, Suite 2500
Seattle, Washington 98154
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U LT "IAA I
HINAGEOSCIENCES INC.
Ulm,
HWAGEOSCIENCES INC.
19730-64TH AVE_ W., SUITE 200
LYNNWOOD, WA 98036-5957
TEL.425-774-0106
October 26, 1998 FAX. 425-774-2714
Revised March 19, 1999 E-MAIL hwa@hongwest.com
HWA Project No. 98032
R. W. Beck
1001 Fourth Avenue, Suite 2500
Seattle, Washington 98154-1004
Attention: Mr. Michael Giseburt, P.E.
Subject: GEOTECHNICAL REPORT
SW 271h Street Culvert Replacement
Renton, Washington
Dear Mike:
Attached is our geotechnical report for the proposed SW 27`h Street Culvert Replacement
project in Renton, Washington. We understand two existing corrugated metal pipe
(CMP) arch culverts beneath the roadway alignment will be replaced with a concrete box
culvert. Previously, we prepared draft versions of the report dated October 9 and October
26, 1998. The following report has been modified to incorporate R.W. Beck's review
comments on the draft report. This report presents recommendations for foundation
support of the replacement culvert, subgrade preparation, lateral earth pressures,
dewatering and general earthwork considerations.
We appreciate the opportunity to provide geotechnical services on this project. Please call
if you have any questions or comments concerning our report, or if we may be of further
service.
Sincerely,
HWA GEOSCIENCES INC.
David L. Sowers, P.E.
Geotechnical Engineer
Enclosure: Geotechnical Report (1 copy)
44-10o,
W. Paul Grant, P.E.
Vice President
GEOLOGY
GEOENVIRONMENTAL SERVICES
HYDROGEOLOGY
GEOTECHNICAL ENGINEERING
TESTING & INSPECTION
TABLE OF CONTENTS
Page
1.0
INTRODUCTION.................................................................................................
1
1.1 GENERAL..................................................................................................
1
1.2 SITE AND PROJECT DESCRIPTION...............................................................
1
1.3 SCOPE OF SERVICES AND AUTHORIZATION.................................................
2
2.0
FIELD AND LABORATORY INVESTIGATIONS .............................................
2
2.1 FIELD INVESTIGATION...............................................................................
2
2.2 LABORATORY TESTING.............................................................................
3
3.0
GEOLOGIC AND SUBSURFACE CONDITIONS ..............................................
3
3.1 GENERAL GEOLOGIC CONDITIONS.............................................................
3
3.2 SOIL CONDITIONS......................................................................................
3
3.3 GROUNDWATER AND SURFACE WATER .....................................................
4
4.0
CONCLUSIONS AND RECOMMENDATIONS.................................................
4
4.1 GENERAL..................................................................................................
4
4.2 CULVERT STRUCTURE(S)...........................................................................
5
4.2.1 Mat Foundation Support and Subgrade Preparation ....................
5
4.2.2 Pile Foundation Support .............................................................
6
4.2.3 Lateral Earth Pressures...............................................................
7
4.2.4 Estimated Settlement..................................................................
8
4.3 BACKFILL PLACEMENT AND COMPACTION .................................................
9
4.4 EXCAVATIONS..........................................................................................
10
4.5 TEMPORARY AND PERMANENT SHORING ...................................................
11
4.6 GROUNDWATER CONTROL/DEWATERING...................................................
11
5.0
UNCERTAINTIES AND LIMITATIONS...........................................................
13
6.0
REFERENCES....................................................................................................
15
LIST OF FIGURES
Figure 1.
Vicinity Map
Figure 2.
Site and Exploration Plan- Alternative 1
Figure 3.
Site and Exploration Plan- Alternative 2
Figure 4.
Cross Section — Alternative 1
Figure 5.
Cross Section — Alternative 2
Figure 6.
Earth Pressures for Temporary Cantilevered Shoring
Figure 7.
Earth Pressures for Permanent Shoring
Appendices
Appendix A: Explorations
Figure A-1. Legend of Terms and Symbols Used on Exploration Logs
Figures A-2 — A-3. Logs of Borings BH-1 and BH-2
Table of Contents (continued)
Appendix B: Laboratory Test Results
Figure B-1. Plasticity Chart
Figures B-2 — B-3. Grain Size Distribution Test Results
98032f ii HWA GEOSCIENCES INC.
GEOTECHNICAL REPORT
SW 27T" STREET CULVERT REPLACEMENT
RENTON, WASIIINGTON
1.0 INTRODUCTION
1.1 GENERAL
This report presents the results of the geotechnical engineering study completed by HWA
GeoSciences Inc. (HWA) for the proposed SW 27`h Street Culvert Replacement project in
Renton, Washington. The project site is located in an industrial area south of Renton, and
is shown on the Vicinity Map, Figure 1. The intersecting alignments of SW 27`h Street
and Springbrook Creek are shown on the Site and Exploration Plans, Figures 2 and 3.
The existing and proposed culvert alignments are also shown on these figures.
1.2 SITE AND PROJECT DESCRIPTION
We understand that the City of Renton plans to replace two 128-inch wide by 83-inch high
corrugated metal pipe (CMP) culverts that convey surface water in Springbrook Creek
from the south side of SW 27t" Street to the north side of the street. Two alternatives
have been presented for replacing these culverts, and are designated as Alternatives 1 and
2. Alternative 1, shown on Figures 2 and 4, consists of a single 30-foot wide by 10-feet
high (inside dimensions) concrete culvert. Alternative 2, shown on Figures 3 and 5,
consists of a 30-foot wide by 6.7-feet high (inside diameter) concrete culvert that would
handle the main Springbrook Creek flow, and a second, 30-foot wide by 4.7-feet high
culvert that would provide capacity in storm, or heavy flow conditions. Each of the
culverts will be 120 feet long. The walls of the proposed concrete culvert(s) are
anticipated to be approximately 10 inches thick and the roof and floor will each be about
14 inches thick.
Current design options that are being considered by R. W. Beck include a four-sided box
culvert or a three -sided culvert with an open channel bottom. The culvert(s) will consist
of either pre -cast concrete sections or a cast -in -place structure. We understand a three -
sided culvert is preferred by the Department of Fisheries. Selection of the three -sided
culvert or four-sided box culvert options for the replacement culvert(s) will be based, in
part, on the most feasible construction methodology, cost, and anticipated performance.
At this time, the City has proposed using temporary wing walls and head walls for the
culvert(s) that would consist of a combination of steel sheet piling and quarry rip rap.
Permanent concrete walls would be constructed in the future when funding was available.
October 26, 1998
Revised March 19, 1999
HWA Project No. 98032
1.3 SCOPE OF SERVICES AND AUTHORIZATION
Our work was conducted in accordance with our proposal letter, submitted by HWA to
R. W. Beck on March 6, 1998. Verbal authorization for the work was subsequently given
by Mr. Michael Giseburt, project manager with R. W. Beck. The scope of work
completed for this project included performing two exploratory borings at the site,
performing laboratory testing, performing engineering analysis based on the conditions
observed in our explorations, and providing geotechnical engineering recommendations
for the proposed culvert(s).
2.0 FIELD AND LABORATORY INVESTIGATIONS
2.1 FIELD INVESTIGATION
On April 27, 1998, HWA performed a subsurface exploration program that included
drilling two exploratory borings (designated BH-1 and BH-2) each advanced to depths of
59 feet below the ground surface. The drilling was subcontracted to Holocene Drilling of
Pacific, Washington. The borings were advanced using a truck -mounted, Mobile B-61
drill rig and hollow -stem auger. The borings were located approximately in the field by
pacing and taping distances from existing site features. The approximate boring locations
are plotted on Figure 2 and should only be considered as accurate as the locating method
implies.
A geotechnical engineer from HWA logged each of the explorations and recorded
pertinent information including sample depths, stratigraphy, soil engineering
characteristics, and groundwater occurrence. Standard Penetration Test (SPT) sampling
was performed using a 2-inch outside diameter split -spoon sampler and a 140-pound
hammer. During an SPT test, a sample is obtained by driving the sampler 18 inches into
the soil with the hammer free -falling 30 inches. The number of blows required for each 6
inches of penetration is recorded. The Standard Penetration Resistance ("N-value") of the
soil is calculated as the number of blows required for the final 12 inches of penetration.
This resistance, or N-value, provides a measure of relative density of granular soils and the
relative consistency of cohesive soils.
Soil samples were classified in the field and representative portions were placed in airtight
plastic bags. These soil samples were then returned to our laboratory for further
examination and testing. The soils were classified in general accordance with the
classification system described in Appendix A on Figure A-1. A key to the boring log
symbols is also presented in Figure A-1. The boring logs are presented on Figures A-2
98032f 2 HWA GEOSCIENCES INC.
October 26, 1998
Revised March 19, 1999
HWA Project No. 98032
and A-3. The stratigraphic contacts shown on the individual logs represent the
approximate boundaries between soil types.
2.2 LABORATORY TESTING
Laboratory tests were conducted on selected samples obtained from our borings to
characterize certain engineering and index properties of the project soils. Laboratory tests
included determination of in -situ moisture content, plasticity characteristics (Atterberg
Limits), and grain size distribution. In -situ moisture content test results are displayed on
the exploration logs in Appendix A, as appropriate. Plasticity characteristics are presented
in Appendix B on Figure B-1. Grain size distribution test results are presented on Figures
B-2 and B-3.
3.0 GEOLOGIC AND SUBSURFACE CONDITIONS
3.1 GENERAL GEOLOGIC CONDITIONS
Geologic information for the site was obtained from the Geologic Map of the Renton
Ouadrangle, King County, Washington (Mullineaux, D.R., 1965). The geologic map
indicates that the area is generally underlain by peat and recent alluvial deposits.
Alluvium, or river -deposited soil, typically consists of interbedded, discontinuous layers of
sand, silt, clay, and organic soils. Alluvium is typically unconsolidated and generally
exhibits low shear strength and high compressibility. Peat and organic soils, in particular,
can experience large deformations when loaded.
3.2 SOIL CONDITIONS
Based on the results of our explorations, the site appears generally underlain by alluvial
sands and silts, consistent with the geologic map. Along the SW 27`h Street alignment, the
alluvium is overlain by fill soils used to construct the roadway. Directly below the
roadway embankment fill, compressible organic silts were observed overlying the
alluvium.
Approximately 9 feet of a surficial roadway fill was encountered in the site borings. The
fill soils generally consisted of medium dense to very dense, slightly gravelly, silty sand. In
our analysis, we assumed that the fill soils had a in situ unit weight of 130 pounds per
cubic foot (pco. These fill materials were placed during original construction of SW 27`'
Street and the development of the industrial park. The pavement consisted of 7 inches of
asphalt over a negligible thickness of base course material.
98032f 3 HWA GEOSCIENCES INC.
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Revised March 19, 1999
HWA Project No. 98032
Organic silt was encountered below the fill to depths of about 17.5 feet (or 8.5 feet thick).
Based on the surrounding topography, it appears that little organic silt material was
removed during road construction. Below the organic silt, borings encountered
interbedded sands, silty sands and silts which ranged from loose to medium dense to soft
to very stiff. The alluvium extended to the full depth in each exploration.
3.3 GROUNDWATER AND SURFACE WATER
The Springbrook Creek flows north through the existing culverts. Surface water level
readings taken in September 1998 indicate the water in the culverts was about I1/2 feet
deep, or at Elevation 7.5 to 8 feet. Groundwater level readings taken during our
exploration program indicate the groundwater is at approximately Elevation 3 feet.
However, during drilling the groundwater level in the borings were not allowed to
stabilize and consequently the water level during drilling is typically lower than the static
groundwater level at the site.
It is anticipated that surface water and groundwater conditions will change in response to
rainfall, level of Springbrook Creek, time of year, and other factors.
4.0 CONCLUSIONS AND RECOMMENDATIONS
4.1 GENERAL
Based on our explorations, the SW 27`" Street alignment is underlain by compressible
organic silts that range from about Elevation 11 feet to Elevation 2.5 feet, or 8.5 feet
thick. In our opinion, further consolidation of the organic material may occur if additional
loads are applied to the materials. The silty sands and non -organic silts (alluvium) which
underlie the alignment are anticipated to provide greater support than the organic material,
providing the loads are well distributed.
We recommend the new structures be designed and constructed on mat foundations
founded on the more competent silty sands and silts, or on pile foundations. Four-sided
box culverts should be supported on mat foundations. The organic silts should be
overexcavated to approximately Elevation 2.5 feet and the overexcavations backfilled with
compacted crushed rock. Pile foundations should be used to support three -sided culverts.
We anticipate that use of strip footings to support the stem walls of a three -sided box
would create an excessive load on the underlying soils and would result in large potential
settlements. Foundations supported on strip footings would also be susceptible to scour.
Consequently, strip footing foundations are not recommended. For a pile supported
culvert, feasible piles types include auger -cast, driven timber piles, or driven pre -cast
98032f 4 HWA GEOSCIENCES INC.
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HWA Project No. 98032
concrete piles. Piles should be embedded well into the underlying alluvial sands to support
the design loads using skin friction and end bearing resistance.
In order create a habitat conducive to fish, we recommend the four -side box culvert(s) be
partially filled with bank run gravel or similar material. The culvert(s) may have to
deepened to accommodate the extra 1 to 2 feet of material and maintain design
stormwater flows.
Groundwater control will play a large role during construction with either mat foundations
or pile foundations. For mat foundations, dewatering will be required to lower the
groundwater level so that excavations and subgrade preparation can be performed during
relatively dry conditions. Pile foundations can be driven under wet or submerged
conditions, but dewatering will still be required to cast concrete pile caps and stem walls.
We anticipate rerouting Springbrook Creek using cofferdams and pumps, and then -
lowering the local groundwater level within the excavation using sumps and pumps. Wells
or well points may also be required depending on the type of culvert structure installed
and the depth of the excavation. Construction dewatering will depend on the time of year,
the level of Springbrook Creek, recent rainfall and other factors.
Geotechnical recommendations for subgrade preparation, mat foundation support, pile
foundations, backfill placement and compaction, temporary excavations and groundwater
control/dewatering are discussed in the following sections.
4.2 CULVERT STRUCTURE(S)
4.2.1 Mat Foundation Support and Subgrade Preparation
Based on the results of our explorations, compressible organic soils extend to
approximately Elevation 2.5 feet. Below the compressible soils, we anticipate loose to
medium dense silty sands and medium stiff silts will be encountered. We anticipate the
silty sands and non -organic silts will provide adequate support of the proposed culvert,
providing they are not unduly disturbed during subgrade preparation. We anticipate that
the weight of the new structure will be slightly greater than the weight of the soil replaced
by the structure. We recommend using a net soil bearing pressure increase of 800 pounds
per square foot (pso for design of the culvert structure (i.e. the structure and backfill
should weigh only 800 psf more than the in situ soil it replaces).
We recommend using a mat foundation, or crushed rock pad, bearing directly on the loose
to medium dense silty sands and medium stiff silts to support the four-sided box culvert.
The crushed rock working pad will help to minimize damage to the subgrade during
placement of precast concrete culvert sections, or during placement of forms and steel
98032f 5 HWA GEOSCIENCES INC.
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Revised March 19, 1999
HWA Project No. 98032
reinforcing for the cast -in -place option. We recommend supporting the 10-foot high
culvert (Alternative 1) and the 6.7-foot high culvert (Alternative 2), on a 2-foot
(minimum) thick layer of crushed rock. For the 4.7-foot high culvert (also Alternative 2),
we recommend using 3 feet of crushed rock and "floating" the structure on the organic
silt; our calculations indicate that there is no increase in load for the 4.7-foot high
structure, located as shown on Figure 5. The crushed rock pad should extend beyond
each end of the box culvert a distance equal to the height of the pad (e.g. 2 feet on each
end for a 2-foot thick pad).
Excavation and subgrade preparation should be observed by the geotechnical consultant.
A geotextile fabric may be used below the crushed rock pad to provide a separation
barrier between the structural fill and the loose, saturated subgrade soils. The geotextile
will prevent the loss of aggregate into the subgrade and minimize upward pumping of fine
grained soil. However, the use of a geotextile will not eliminate the need to overexcavate.
Crushed rock for overexcavations and for the working pad should be placed and
compacted as described in Section 4.3.
4.2.2 Pile Foundation Support
If three -sided box culverts are used for the culvert replacement project, we recommend
supporting the abutments, or stem walls, using pile foundations. Compared to strip
footings, pile foundations will provide more support if the subgrade liquefies during a
seismic event, and the pile supported structure would be more resistant to potential scour,
and will exhibit negligible differential settlements. Pile foundations could consist of either
auger -cast piles, or driven piles such as timber or pre -cast concrete piles. The following
paragraphs present preliminary design recommendations and installation methods,
including potential pile embedments and diameters, for each of the recommended pile
types.
Auger -cast Piles — Auger -cast concrete piles consist of cast -in -place reinforced drilled
shafts. Auger -cast piles are installed by rotating a continuous -flight hollow -stem auger to
a pre -determined depth, and pumping a sand -cement grout under controlled pressure
through the center of the shaft as the auger is slowly withdrawn. By maintaining pressure
in the grout line and slowly extracting the auger no faster than an equivalent volume of
grout is pumped, a continuous column of concrete is formed. A single reinforcing rod can
be installed for the full pile length through the hollow -stem of the auger, and/or, a
reinforcing cage can be placed in the column.
The allowable capacity of auger -cast concrete piles at the site will vary with pile length
and diameter. Axial capacity is based on skin friction resistance and end bearing
98032f 6 HWA GEOSCIENCES INC.
October 26, 1998
Revised March 19, 1999
HWA Project No. 98032
resistance. For preliminary planning and estimating purposes, we anticipate a 24-inch
auger cast pile could support an average skin friction resistance of 2.5 kips per liner foot
of pile and a tip resistance of 10 kips per square foot. These allowable resistances include
a factor of safety of 2.5 for skin resistance and 3.0 for tip resistance. Based on this
estimate, a 24-inch auger -cast pile supporting an allowable design load of 65 tons (130
kips) would have to be approximately 40 feet long.
Driven Piles — Timber and pre -cast concrete piles could also be used to support the
proposed structure. Timber and pre -cast concrete piles can be easily driven into the
relatively loose to medium dense sands that underlie the site using a steam or diesel impact
hammer. Timber piles are the cheaper alternative of the two but are usually limited to
shorter lengths; 30 to 40 feet long timber piles are common, with longer lengths available
at higher cost. A 12-inch to 14-inch timber pile can be expected to support an allowable
axial capacity of approximately 1.5 kips per linear foot of pile (this includes a factor of
safety of 2.0) if embedded sufficiently into the alluvial soils at the site. Based on this
analysis, a 40-foot long pile will provide an allowable axial capacity of 30 tons, or 60 kips.
If timber piles are sufficiently embedded below the groundwater surface, chemical
treatment (creosote) is not necessary. However, if piles will be exposed to air for any
period of time, we recommend they be treated to resist decay.
Concrete piles can be cast in various lengths and diameters and are pre -stressed with steel
reinforcing. We anticipate 14-inch square and 16'/2-inch octagonal piles can support loads
of approximately 2 kips per linear foot and 2.5 kips per linear foot, respectively. Based on
this analysis, a 40-foot long pile will provide allowable axial capacities of 40 tons (80 kips)
and 50 tons (100 kips) per pile, respectively. The capacities per linear foot listed here
include both skin friction resistance and end bearing, and a factor of safety of 2.0.
4.2.3 Lateral Earth Pressures
For the four-sided box culvert founded on a mat foundation, it is anticipated that the
proposed structural walls will be restrained against rotation and will have relatively level
backfill. As such, the box culvert(s) should be designed for a horizontal at -rest equivalent
fluid weight of 55 pounds per cubic foot (pcf) above the design groundwater elevation and
91 pcf below the design groundwater elevation; the value of 91 pcf includes hydrostatic
pressure. These values should also be used for three -sided box culvert walls. This
recommendation assumes that the backfill behind the subsurface walls will consist of
properly compacted structural fill, and does not include adjacent surcharge loads. If the
below -grade walls will be subjected to the influence of surcharge loading during
construction, e.g. excavators or semi -trucks, within a horizontal distance equal to or less
than the height of the walls, the walls should be designed for the additional loads. We
98032f 7 HWA GEOSCIENCES INC.
October 26, 1998
Revised March 19, 1999
HWA Project No. 98032
typically assume traffic surcharge loading is equivalent to a uniformly distributed load at
the ground surface of 250 psf. Using this value, traffic surcharge loading within a distance
less than the height of the wall could be determined using an equivalent fluid weight of 75
pcf applied as a uniform rectangularly distributed load over the height of the wall.
During a seismic event, lateral earth pressures acting on below -grade structural walls will
increase by an incremental amount that corresponds to the earthquake loading. A
concomitant decrease in passive earth pressure also occurs. However, if at -rest earth
pressures are used in design, a conservative structural design that can readily
accommodate the temporary seismic overloading conditions generally results. Therefore,
it is our opinion that the dynamic incremental pressures from earthquake loading may be
neglected if the below -grade structures are designed based on at -rest earth pressures.
Lateral forces acting on the three -sided culvert will be resisted by the lateral stiffness of
the driven or drilled piles. HWA can provide criteria for calculating lateral capacities of
piles in the final report if this foundation option is selected.
4.2.4 Estimated Settlement
Differential settlement can occur between two foundation systems when one system settles
more quickly than the other. Because the site is underlain by compressible organic soils,
we anticipate that settlement of SW 27'I' Street will continue to occur. Potentially
differential settlement could occur between the settling roadway embankment/pavement
and a culvert structure not supported on organic material. Currently, the arch CMP
culverts are supported in/on the organic silt and are most likely settling at the same rate as
the surrounding roadway embankment. However, structures founded on piles and
structures founded on less compressible alluvial sands will settle at a noticeable different
rate. As a result, movement across the footprint of the new culvert(s) could cause
transverse cracking to develop in the pavement.
Bedding the box culvert structure in accordance with the recommendations described
above, including removal of soft and/or organic soils from below the new culvert, will help
reduce the potential for differential settlement. We anticipate that the culvert and backfill
will weigh slightly more than the existing soil that it will displace. In our opinion, this
pressure increase is relatively minor and potential settlement of the structure will depend
largely on the contractor's methods and the amount of subgrade disturbance which occurs
during construction.
The extent of disturbance to the subgrade will depend, in part, on whether the structure is
constructed in a dry or wet condition. Under ideal conditions, total post -construction
settlement of the four-sided box culvert structure due to the increase in load may be less
9803217 8 HWA GEOSCIENCES INC.
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Revised March 19, 1999
HWA Project No. 98032
than '/2 inch. However, based on the subsurface conditions anticipated and the disturbance
expected if construction is performed in the dry, we estimate total settlement may be on
the order of 1 inch. If construction is performed in the wet, we anticipate maximum
settlements will be on the order of 2 inches.
Settlement from construction of the new box culvert will impact the supporting backfill
soils around the existing utilities. Evaluations should be performed to verify that the
existing pipelines can accommodate the magnitudes of settlement estimated above, which
will depend on the method of installation.
Sand boils at the bottom of the excavation or subgrade soils disturbed during construction
could result in settlement of the structure. Occurrence of sand boils can be minimized by
proper construction dewatering, and/or providing sufficient sheet pile embedment below
the bottom of excavation to provide base stability. In the event of sand boils or subgrades
disturbed by construction activities, a minimum of the upper 12 inches of disturbed
material should be removed and replaced with compacted crushed rock.
4.3 BACKFILL PLACEMENT AND COMPACTION
All materials used for backfilling overexcavations of unsuitable soils, and used for the
crushed rock working pad should consist of materials meeting the requirements for
Crushed Surfacing Base Course, as described in Section 9-03.9(3) of the 1998 WSDOT
Standard Specifications for Road, Bridge, and Municipal Construction (1998 WSDOT
Standard Specifications). Materials used to backfill excavations for the culvert should
consist of Bank Run Gravel for Trench Backfill, as described in Section 9-03.19 of the
1998 WSDOT Standard Specifications.
The results of our investigation indicate the in situ fill soils, as denoted on our logs directly
below the pavement surface to a depth of approximately 8 to 9 feet (Elevation 11 feet),
may be used as structural fill. The existing fill soils are at/near their anticipated optimum
moisture content and contain about 10 to 20 percent fine grained (silt and clay) soil.
Consequently, care must be taken so that further moisture is not added to the excavated
soils. If organic materials are encountered in the existing fill they should be removed. The
organic rich silt underlying the existing fill should not be used as structural fill and should
only be used in areas where some settlement can be tolerated, such as landscaping areas.
Use of the existing fill is dependent on the ability of material to meet the compaction
criteria.
During placement of the initial lifts, the backfill material should not be bulldozed into the
excavation or dropped directly on the structure. Furthermore, heavy vibratory equipment
98032f 9 HWA GEOSCIENCES INC.
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Revised March 19, 1999
HWA Project No. 98032
should not be permitted to operate directly over the structure until a minimum of 3 feet of
backfill has been placed.
In order to minimize subsequent settlement of the excavation backfill, new pavements, and
existing utilities, we recommended that backfill soils be placed in horizontal lifts less than
8 inches in thickness, and compacted to at least 95 percent of maximum dry density, as
determined using test method ASTM D 1557 (Modified Proctor). The procedure to
achieve proper density of compacted fill depends on the size and type of compaction
equipment, the number of passes, thickness of the layer being compacted, and certain soil
properties. When access restricts the use of heavy equipment, smaller equipment can be
used, but the soil must be placed in thin enough lifts to achieve the required compaction.
4.4 EXCAVATIONS
Installation of the proposed culverts will involve open cuts. We anticipate excavations can
be accomplished with conventional equipment such as backhoes and trackhoes.
Excavations are anticipated to have maximum depths on the order of 20 feet below the
existing ground surface for the 30-foot by 10-foot box culvert (Alternative 1) and the 30-
foot by 6.7-foot box culvert (Alternative 2). Excavations for the 30-foot by 4.7-foot box
culvert (Alternative 2) will require excavations on the order of 17 feet below the pavement
surface.
Providing the site is dewatered below the depth of the cut, temporary excavations can be
sloped at 1'/2H:1 V (horizontal: vertical) or flatter. This allowable cut slope inclination is
applicable to excavations above the water table only. If excavations extend below the
water table, flatter side slopes will be required; the slope angle should be monitored and
adjusted in the field based on local subsurface conditions and the contractor's methods.
With time and the presence of seepage and/or precipitation, the stability of temporary
unsupported cut slopes can be significantly reduced. Therefore, all temporary slopes
should be protected from erosion by installing a surface water diversion ditch or berm at
the top of the slope and by covering the cut face with well -anchored plastic sheets. In
addition, the contractor should monitor the stability of the temporary cut slopes and adjust
the construction schedule and slope inclination accordingly.
Excavation and construction of the new culverts must be performed in a manner which
will not impact existing utilities. Temporary support and protection of the existing gas,
water, phone, and power lines must be must be provided and maintained during
construction. For existing utilities, we recommend using bracing or come -a -longs
strapped to H-beams to support large spans of the existing utilities and minimize sagging.
98032f 10 HWA GEOSCIENCES INC.
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HWA Project No. 98032
4.5 TEMPORARY AND PERMANENT SHORING
We understand a minimum of one lane of the existing roadway will be in use during
construction. Consequently, temporary shoring is expected to be required where
excavations encroach on the existing roadways. For these cases, we recommend using
steel sheet piling designed to withstand the lateral earth pressure and surcharge loading
against the shored wall. Design parameters for temporary sheet pile walls are shown on
Figure 6. We recommend that the contractor be required to submit a shoring/excavation
plan for the review of the project engineer prior to construction. The plan should be
required to contain specific measures for temporary support and protection of the existing
utilities and structures.
We understand that the City of Renton does not want to install permanent (concrete)
headwalls and wingwalls at the entrances to the proposed culvert(s). We propose
constructing headwalls and wingwalls with sheet piling and quarry riprap. For this
application, the sheet piling should be designed as shown on Figure 7. The fill and riprap
should be placed no steeper than 11/2H:1 V behind of and in front of the wall. Riprap
should meet the requirements for Hand Placed Riprap, as described in Section 9-13.2 of
the 1998 WSDOT Standard Specifications. We recommend the riprap extend the full
length of the sheet pile headwalls and wingwalls, and that the riprap should be piled at
least three feet high.
4.6 GROUNDWATER CONTROUDEWATERING
We recommend implementing construction dewatering measures before subgrade
excavation begins. Construction dewatering is important because it will be very difficult
to prepare subgrade, evaluate subsurface conditions, and construct structures underwater.
Placement of backfill material will also be difficult under submerged conditions.
Groundwater seepage into the open excavation will tend to destabilize side slopes and
increase lateral loads on temporary shoring systems. In addition, groundwater flow into
the excavation can cause sand boils or heaving at the bottom of excavations. Because of
these impacts dewatering should be accomplished so that culvert construction can be
completed in the dry. We recommend that temporary excavations be dewatered to
maintain the groundwater level at least 2 feet below the base of the excavation.
Dewatering should continue until the culvert has been placed and backfilled, and is capable
of resisting hydrostatic forces.
Recently, a box culvert crossing project was completed for the Olympic Pipe Line
Company at the nearby intersection of Lind Avenue and SW 23`d Street. Completed in
September, 1998, the subgrade conditions at the site were very similar to the conditions at
98032f I I HWA GEOSCIENCES INC
October 26, 1998
Revised March 19, 1999
HWA Project No. 98032
SW 27t' Street and dewatering of the site required the use of cofferdams, sumps, and deep
wells. Based on the experience at that site and the subsurface conditions observed in
boring BH-1 and BH-2, the following general guidelines can be used for dewatering
estimates. These estimates assume that construction occurs in the drier summer months
and that a storm event does not occur during the duration of the project.
Springbrook Creek should be dammed using cofferdams upstream and downstream of
the crossing (e.g. a combination of sand bags, ecology blocks, and steel sheets) and
then rerouted with pumps. The cofferdams will drop the surface water level in the
channel to slightly below the bottom of the existing arch culvert invert (to Elevation f
6 feet).
Sumps can be used to further drawdown the groundwater level about 2 to 3 feet,
depending on the spacing and depth of the sump (to Elevation f 3 to 4 feet).
12-inch wells located on 25- to 30-foot spacings and pumping 15 to 20 gallons per
minute can drawdown the groundwater level another 3 to 4 feet (to Elevation ± 0
feet). To accomplish this, wells should be between 20 and 30 feet deep.
In our opinion, a combination of the above dewatering measures will allow excavations to
extend to a depth of approximately 20 feet below the existing ground surface under ideal
weather conditions and allow construction to be completed in relatively dry conditions.
Extended dewatering could result in lowering the water table over a large area which
would cause settlement of the underlying alluvial soils. The magnitude of the settlement
and its lateral extent would depend on the amount of change in the water level; the length
of time the water level was lowered; and the compressibility, thickness, and permeability
of the underlying soils. Based on the soil conditions encountered during our site
investigation, and the proposed dewatering plan described above, we estimate that the
areas that may be impacted by groundwater drawdown could extend about 40 to 50 feet
away from dewatered excavations. We estimate maximum settlements of the soil within
this zone of influence as the result dewatering operations would be on the order of 1 to
1'/2 inches. Settlement will be greatest where groundwater drawdown is at a maximum,
and will decrease with increasing distance from the dewatered area; i.e. 20 feet from the
well the settlements may be approximately one-third of the above settlements, 50 feet from
the well the settlements are estimated to be negligible. Dewatering within a sheet pile
enclosed excavation with sufficient sheet pile embedment acting as a cut-off wall to
groundwater flow will result in less groundwater discharge and drawdown over smaller
areas. As a result, less settlement of the adjacent soils would be expected where sheet
piling is used.
98032f 12 HWA GEOSCIENCES INC.
October 26, 1998
Revised March 19, 1999
HWA Project No. 98032
The extent of dewatering-related groundwater drawdown should be monitored during
construction to minimize the potential for settlement damage. Prior to construction, the
contractor should determine an appropriate dewatering scheme and submit a dewatering
plan to the project engineer for review.
5.0 UNCERTAINTIES AND LIMITATIONS
We have prepared this report for use by the City of Renton and R. W. Beck in design of a
portion of this project. This report should be provided in its entirety to prospective
contractors for bidding or estimating purposes; however, the conclusions and
interpretations presented should not be construed as a warranty of the subsurface
conditions. Experience has shown that subsurface soil and groundwater conditions can
vary significantly over small distances. Inconsistent conditions can occur between
explorations and may 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.
We recommend that HWA be retained to review the plans and specifications and to
monitor the geotechnical aspects of construction, particularly construction dewatering,
excavation, subgrade preparation, bedding and backfill placement and compaction, and
pile driving (if necessary).
The scope of our work did not include environmental assessments or evaluations
regarding the presence or absence of wetlands or hazardous substances in the soil, surface
water, or groundwater at this site.
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.
•O
98032f 13 HWA GEOSCIENCES INC.
October 26, 1998
Revised March 19, 1999
HWA Project No. 98032
We appreciate this opportunity to be of service.
Sincerely,
HWA GEOSCIENCES INC.
J1� SO
0
. 'O �or3381rt3� k'¢
VALF�
EXPIRES
David L. Sowers, P.E.
Geotechnical Engineer
V�
W. Paul Grant, P.E.
Vice President
98032f 14 HWA GEOSCIENCES INC.
October 26, 1998
Revised March 19, 1999
HWA Project No. 98032
6.0 REFERENCES
Mullineaux, D. R., 1965, Geologic Map of the Renton Quadrangle, King County,
Washington, United States Geological Survey.
WSDOT, 1998, Standard Specifications for Road, Bridge, and Municipal Construction.
98032f 15 HWA GEOSCIENCES INC.
N
LL
900
enton
LFos If Course N f
900 Q. 169
900
900
Tukwila B,
G
Z
N
LLongacres Race Track i
167
515
181 PROJECT
LOCATION
103R A
Pg�
180 Or7lia 0T
® 1993 ReLome Mauvinst 1 i
NOT TO SCALE
SW 27TH STREET VICINITY MAP
CULVERT REPLACEMENT
fMGW"NaS INC RENTON, WASHINGTON
PROJECT NO.:98032 FIGURE: 1
D: JOBS 98032 98032001.DYG
SPRINGBROOK CREEK
LEGEND
BH-1 BORING DESIGNATION AND
APPROXIMATE LOCATION
A A'
��► CROSS SECTION LOCATION
REFERENCE: Base map provided by R. W. BECK.
0' 10' 0' 40'
SCALE: 1 "=20'
amn
HWAGEOSCIENCES INC.
SW 27TH STREET SITE AND
CULVERT REPLACEMENT EXPLORATION PLAN
RENTON, WASHINGTON ALTERNATIVE 1
PROJECT NO.:98032 FIGURE: 2
SPRINGBROOK CREEK
LEGEND
13H-1 BORING DESIGNATION AND
APPROXIMATE LOCATION
A A'
CROSS SECTION LOCATION
REFERENCE: Base map provided by R. W. BECK.
0' 10' 20' 40'
SCALE: 1 "=20'
SW 27TH STREET SITE AND
CULVERT REPLACEMENT EXPLORATION PLAN
HWAGEOSCIENCES INC RENTON, WASHINGTON ALTERNATIVE 2
PROJECT NO.:98032 FIGURE: 3
PROPOSED
LEGEND
T
m
EXISTING BOX CULVERT
N
o ARCH CULVERTS
A
a w
w
= SW 27TH STREET
At
WEST
= � o
�w ~
o
=� o
EAST
m "z PAVEMENT
ma N
20
20
14
g
-
23
nW
10
�����ti�ti�ti��ti�ti�
00 00 00 00
�:: op
o�0
/vn'y ^1...!i.�� I� T� .Y�. ?v 'r7.: di.i /'-:C• ...•.�� �.
n ^IL.LL• �n L.Ljd
0
...
r.
0
11
10
w
w
24
28
Z
_
z
z -10
-
-10
o
3
7
z
0
Q
Q
w
16
18Ld
-20
28
24
28 .. .
22
-30
-30
52 : - ' ...
38
35
12
-40
-40
BORING DESIGNATION
AND APPROXIMATE LOCATION
TOP OF BORING
GROUNDWATER LEVEL DURING
DRILLING
10 SPT BLOWCOUNT
END OF BORING
0' S' 10' 20'
NOTE
® Location and elevations of existing and proposed culverts
SCALE: 1
FI LL "=10' are based on profiles provided by R.W. Beck.
ORGANIC SILT
SAND, SILTY SAND, SILT (ALLUVIUM) ,
SW 27TH STREET CROSS SECTION A -A
CRUSHED ROCK (PROPOSED FILL) CULVERT REPLACEMENT ALTERNATIVE 1
HWAGEOSCIENCES INC. RENTON, WASHINGTON
PROJECT NO.:98032 FIGURE: 4
LEGEND
r
co
0
L
M
A PROPOSED
w-- BOX CULVERTS
WEST o
= ��
=aUf
mvz PAVEMENT
20
10
I
—20
—30
�e7
EXISTING
ARCH CULVERTS o
w--� SW 27TH STREET
A'
EAST
--------------------
------------------
------------------
BORING DESIGNATION
AND APPROXIMATE LOCATION
TOP OF BORING
GROUNDWATER LEVEL DURING
DRILLING
10 SPT BLOWCOUNT
END OF BORING
0' 5' 10' 20'
® FI LL SCALE: 1 "=10'
ti ORGANIC SILT
SAND, SILTY SAND, SILT (ALLUVIUM) el
CRUSHED ROCK (PROPOSED FILL) ,
HWAGEOSCIENCES INC.
NOTE
Location and elevations of existing and proposed culverts
are based on profiles provided by R.W. Beck.
SW 27TH STREET CROSS SECTION A -A'
CULVERT REPLACEMENT ALTERNATIVE 2
RENTON, WASHINGTON
PROJECT NO.:98032 FIGURE: 5
ASSUME GROUNDWATER
AT GROUND SURFACE
FnR nFSIGN
)ILE WALL OR
ONE LEVEL
4TION
2' GROUNDWATER DRAW
7 DOWN IN EXCAVATION
62.4(H+2) ( 18(H+D) } 240D I
ULTIMATE
HYDROSTATIC ACTIVE EARTH PASSIVE EARTH
PRESSURE PRESSURE, psf PRESSURE, psf
NOTES:
1. Recommended lateral earth pressure values assume subsurface soils
consist of fill and alluvium.
2. The active and passive pressures do not include the effects of wall friction.
3. Sufficient embedment should be provided to achieve base stability,
and to minimize impacts of dewotering to surrounding areas.
4. Surcharge loads should be added to the active pressure where
appropriate.
5. A factor of safety has not been applied to the recommended
earth pressure values.
6. All units in feet and pounds
Yam' SW 27TH STREET EARTH PRESSURES FOR
CULVERT REPLACEMENT TEMPORARY SHORING
flONGWEST RENTON, WASHINGTON
&ASSOCIATES. INC. PROJECT NO.:98032 FIGURE: C
C:\JOBS\98032\98032006.DWG
1 1/21-1 1V MIN,
FILL
V
CANTILEVERED SHEET
PILE WALL
H
RIP RAP (see text)
STREAM BED
DESIGN
GROUNDWATER
LEVEL
D
15D (W+33)H 2O0D
ACTIVE EARTH ULTIMATE
PRESSURE, psf PASSIVE EARTH
PRESSURE, psf
NOTES:
1. Recommended lateral earth pressure values assume subsurface soils
consist of loose alluvium.
2. It is assumed that drainage is provided so that water pressures do
not act on the wall above the bottom of stream bed.
3. For contilevered walls, the embedded height of the wall, D, should
be at least 1.5 times the unsupported height.
4. The angle of the bockslope is rP.
SW 27TH STREET
CULVERT REPLACEMENT
HWAGEOSCIENCES INC. RENTON, WASHINGTON
tNl'C In rr\C.7.)UI\LJ
FOR PERMANENT SHORING
PROJECT NO.:98032
7
c:
APPENDIX A
FIELD EXPLORATIONS
RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALUE
COHESIONLESS SOILS
COHESIVE SOILS
Approximate
Approximate
Density
N (blowslft)
Relative Density(%)
Consistency
N (blows/ft)
Undrained Shear
Strength (psf)
Very Loose
0 to 4
0 15
Very Soft
0 to 2
<250
Loose
4 to 10
15 - 35
Soft
2 to 4
250 - 500
Medium Dense
10 to 30
35 - 65
Medium Stiff
4 to 8
500 - 1000
Dense
30 to 50
65 - 85
Stiff
8 to 15
1000 2000
Very Dense
over 50
85 - 100
Very Stiff
15 to 30
2000 - 4000
Hard
over 30
>4000
USCS SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS
GROUP DESCRIPTIONS
Coarse
Grained
Gravel and
Gravelly Soils
Clean Gravel
(little or no fines)
0 0
GW
Well -graded GRAVEL
-I
GP
Poorly -graded GRAVEL
Soils
More than
50% of Coarse
Gravel with
. 1�
GM
Silty GRAVEL
Fraction Retained
on No. 4 Sieve
Fines (appreciable
amount of fines)
GC
Clayey GRAVEL
Sand and
Clean Sand
SW
Well -graded SAND
More than
Sandy Soils
(little or no fines)
SID
Poorly -graded SAND
50% Retained
on No.
200 Sieve
Size
50% or More
of Coarse
Fraction Passing
No. 4 Sieve
Sand with
Fines (appreciable
amount of fines)
SM
Silty SAND
SC
Clayey SAND
MIL
SILT
Fine
Grained
Soils
silt
and Liquid Limit
Less than 50%
Clay
CL
Lean CLAY
_
—
OL
Organic SILT/Organic CLAY
Mf'I
Elastic SILT
50% or More
Passing
No. 200 Sieve
Size
Silt and Liquid Limit
Clay 50% or More
y
CH
Fat CLAY
01 I
Organic SILT/Organic CLAY
Highly Organic Soils
PT
PEAT
COMPONENT DEFINITIONS
COMPONENT
SIZE RANGE
Boulders
Larger than 12 in
Cobbles
3 in to 12 in
Gravel
3 in to No 4 (4.5mm)
Coarse gravel
3 in to 3/4 in
Fine gravel
3/4 in to No 4 (4.5mm)
Sand
No. 4 (4.5 mm) to No. 200 (0.074 mm)
Coarse sand
No. 4 (4.5 mm) to No. 10 (2.0 mm)
Medium sand
No. 10 12.0 mm) to No. 40 (0.42 mm)
Fine sand
No. 40 10.42 mm) to No. 200 (0.074 mm)
Silt and Clay
Smaller than No. 200 (0.074mm)
TEST SYMBOLS
%F Percent Fines
AL Atterberg Limits: PL = Plastic Limit
ILL = Liquid Limit
CBR California Bearing Ratio
CN Consolidation
DO Dry Density (pcf)
DS Direct Shear
GS Grain Size Distribution
K Permeability
MD Moisture/Density Relationship (Proctor)
MR Resilient Modulus
PID Photoionization Device Reading
PP Pocket Penetrometer
Approx. Compressive Strength (tsf)
SG Specific Gravity
TC Triaxial Compression
TV Torvane
Approx. Shear Strength (tsf)
UC Unconfined Compression
SAMPLE TYPE SYMBOLS
®2.0" OD Split Spoon (SPT)
(140 lb. hammer with 30 in. drop)
IShelby Tube
3.0" OD Split Spoon with Brass Rings
OSmall Bag Sample
Large Bag (Bulk) Sample
Core Run
Non-standard Penetration Test
(with split spoon sampler)
GROUNDWATER SYMBOLS
Q Groundwater Level (measured at
time of drilling)
1 Groundwater Level (measured in well or
open hole after water level stabilized)
COMPONENT PROPORTIONS
PROPORTION RANGE
DESCRIPTIVE TERMS
< 5%
Clean
5 - 12%
Slightly (Clayey, Silty, Sandy)
12 - 30%
Clayey, Silty, Sandy, Gravelly
30-50%
Very (Clayey, Silty, Sandy, Gravelly)
Components are arranged in order of increasing quantities.
NOTES: Soil classifications presented on exploration logs are based on visual and laboratory
observation in general accordance with ASTM D 2487 and ASTM D 2488. Soil descriptions MOISTURE CONTENT
are presented in the following general order:
DRY Absence of moisture, dusty,
Densiry/consistency, color, modifier (if any) GROUP NAME, additions to group name (if any), moisture content. dry to the touch.
Proportion, gradation, and angularity of constituents, additional comments. (GEOLOGIC INTERPRETATION) MOIST Damp but no visible water.
Please refer to the discussion in the report text as well as the exploration logs for a more WET Visible free water, usually
complete description of subsurface conditions. soil is below water table.
LEGEND OF TERMS AND
SW 27th Street Culvert Replacement SYMBOLS USED ON
HWAGEOSCIENCES INC. Renton, Washington EXPLORATION LOGS
PROJECT NO.: 98032 FIGURE: A-1
LEGEND 98032 9/26/98
DRILLING COMPANY: Holocene LOCATION: See Figure 2
DRILLING METHOD: HSA, split spoon sampler DATE COMPLETED: 4/27/98
SURFACE ELEVATION: 21 t Feet LOGGED BY: MB
5
10
15
20
25
30
35
0
Q
J
U
¢
w
w
U .-
x
a
co
Q r
(n
~
Standard Penetration Resistance
>-
Z
c
w
3
(140 lb. weight, 30" drop)
w
(n m
Z
♦ Blows per foot
=
Lu
a.
a
0 Ncc
w
D
=
2
2
Z o
=
O
a
DESCRIPTION (n
a)
a
O
t7
0 10 20 30 40 50
Uj
O
7" asphalt concrete.
SM
Medium dense to very dense, dark yellowish
brown, slightly gravelly, silty SAND, moist.
Fine to coarse sand. Fine to coarse, angular to
subrounded gravel.
(FILL)
Dark brown silt containing organic matter in
the sampler tip.
OH
Soft, very dark borwn, ORGANIC SILT, moist.
Contains organics, wood, leaves, reeds.
i/
/j
/j
/j
/j
/j
SM
Loose to medium dense, dark grayish brown to
very dark brown, silty SAND, wet. Fine to
medium sand.
(ALLUVIUM)
Very stiff, dark gray, sandy SILT, wet Fine
ML
sand.
Loose to dense, very dark gray, silty SAND,
SM
wet. Fine to coarse sand. Contains silty
layers.
--------------------------
•
S-1
16-28-28
...... ...... ...... _...... ...... ....... ...... _...... E...... _ ..
5
S-2
13-17-6
....... ...... ...... `...... €......_...... ...... _ .......- .
10
1
S-3
1-1-2 —
......''s...... _ ...... ...... ............'...................15
Q
S-4
2-7-10 —
............ ............ ...... :...... _...... ..... _ .
2 0
S-5
2-5-5
.....:....
...... _...... ...... _...... ...... z......€......_...... . _ ..
2 5
S-6
7-14-14 %F
........................_............ _....................30
S-7
4-4-3 %F
...... _...... ...... _...... ...... _...... ......_...... _ ..
5
S-8
3-8-10
40
4
0 20 40 60 80 100
Water Content (%)
Plastic Limit 1--0 Liquid Limit
Natural Water Content
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
1
SW 27th Street Culvert Replacement BORING: BH-1
HMGEOSCIENCES INC Renton, Washington PAGE: 1 of 2
PROJECT NO.: 98032 FIGURE: A-2
BORING 98032 1019/98
DRILLING COMPANY: Holocene
LOCATION: See Figure 2
DRILLING METHOD: HSA, split spoon sampler
DATE COMPLETED: 4/27/98
SURFACE ELEVATION: 21 t Feet
LOGGED BY: MB
cn
a
0:
w
W
U
U
a
Q r
U
H Standard Penetration Resistance
�
Z
u~i
Lo
3 (140 lb. weight, 30" drop)
Jo
J J
w co
w
Z ♦Blows per foot
Z o
0 a) Q DESCRIPTION
can ai
a
0
0
0 10 20 30 40 50
Lu
0
40
:.
SP
Medium dense to dense, dark gray, fine to
SAND.
40
medium
S-9
11-11-13
GS
45
Encountered some shells.
....... ...... ...... ...•••• ......- • • - -
45
�S-10
8-11-11
50-
55-
60-
65-
70-
75-
End of borehole at 59.0 feet.
Groundwater seepage observed at 17.5 feet at
time of boring.
alm"I
�S-11 10-18-20
�S-12 6-7-5
......_...... ....... ...... :...... ............ _ ............ _ ...... 6 0
...... :...... _...... :...... ;...... :....... ......I )---65 1
210"1
....... ............ ...... ...... _...... 1 �-75 1
80J 80
0 20 40 60 80 100
Water Content M
Plastic Limit 1-0 Liquid Limit
Natural Water Content
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
0 USW 27th Street Culvert Replacement BORING: BH-1
HMGEOSCIENCES INC Renton, Washington PAGE: 2 of 2
PROJECT NO.: 98032 FIGURE: A-2
BORING 98032 10/9/98
DRILLING COMPANY: Holocene LOCATION: See Figure 2
DRILLING METHOD: HSA, split spoon sampler DATE COMPLETED: 4/27/98
SURFACE ELEVATION: 20 t Feet LOGGED BY: MB
rn
In
J
U
5
1E
2C
2E
30
35
0
DESCRIPTION
M
W
d Co
Q r
H
H
Standard Penetration Resistance
Z
c~n c
w
3
(140 lb. weight, 30" drop)
w w
w cD
o
♦ Blows per foot
d 0_
= H
W
D
2
ZO
2
O
o.
ai vai
a _,
O
O
0 10 20 30 40 50
LU
0
S-1 7-7-7
S-2 3-4-5
S-3 1-2-3
S-4 2-2-4
S-5 5-2-9 GS
S-6 5-11-13
MW
15 1
20 1
25 1
M
S-7 2-2-1
_...... _...... _. ...... _.. 35
S-8 2-6-10 GS
4 40
0 20 40 60 80 100
Water Content M
Plastic Limit 1-0---i Liquid Limit
Natural Water Content
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
SM
Loose to medium dense, dark yellowish brown,
slightly gravelly, silty SAND, moist. Fine to
coarse sand. Fine to coarse subrounded
gravel. Trace organics, grass, roots.
(FILL)
ORGANIC
OH
Medium stiff, very dark brown, SILT,
moist. Contains organics, peat, reeds, leaves.
/j
SM
Loose to medium dense, dark grayish brown,
silty SAND, moist to wet. Fine to medium
sand. Trace organics, grass.
(ALLUVIUM)
--------------------------
Soft to stiff, very dark grayish brown, very
ML
sandy SILT, moist to wet. Fine to medium
sand.
At 27.5 feet grades to very stiff SILT with
trace of fine sand. Contains trace fibrous
organics matter.
At 32.5 feet grades to dark gray, sandy SILT,
wet. Fine sand. Trace shells in sampler tip.
Medium dense to dense, dark gray, silty SAND,
rSM
wet. Fine to medium sand. Trace organics,
wood fragments.
BOA SW 27th Street Culvert Replacement BORING: BH-2
HMGEOSCIENCES INC Renton, Washington PAGE: 1 of 2
PROJECT NO.: 98032 FIGURE: A-3
BORING 98032 1019/98
DRILLING COMPANY: Holocene LOCATION: See Figure 2
DRILLING METHOD: HSA, split spoon sampler DATE COMPLETED: 4/27/98
SURFACE ELEVATION: 20 t Feet LOGGED BY: MB
to
Q
J
U
1 45
1 50
1 55
1 60
1 65
75
DESCRIPTION
End of borehole at 59.0 feet.
Groundwater seepage encountered at 17.5 feet
at time of boring.
W
Lu coQ
0
H
LU
Standard Penetration Resistance
>- Z
ai c
(140 lb. weight, 30" drop)
J J
LU)+' CO
w
Z
Blows per foot
=
Q N
3
W
D
Z o
N U)
a'
O
Q
0 10 20 30 40 50
0
40
S-9
13-14-14
` • ` I
�S-10 12-12-16
�S-11 15-23-29 ` ?
�S-12 9-15-20
)-50 1
i-55 I
♦-60 1
J L
80 0 20 40 60 80 100 80
Water Content M
Plastic Limit 1--0 Liquid Limit
Natural Water Content
NOTE: This log of subsurface conditions applies only at the specified location and on the date indicated
and therefore may not necessarily be indicative of other times and/or locations.
ff"M& I SW 27th Street Culvert Replacement BORING: BH-2
HMGEOSCIENCES INC Renton, Washington PAGE: 2 of 2
PROJECT NO.: 98032 FIGURE: A-3
BORING 98032 10/9/98
APPENDIX B
LABORATORY TEST RESULTS
80
70
CL
X 60
OOF
w
0
Z
y. 50
F-
U_
F-
Q 40
o_
30
20
40
50 60 70
80 90 100 110 120 30
0
50
LIQUID LIMIT (LL)
SYMBOL
SAMPLE DEPTH (ft)
CLASSIFICATION
% MC
LL Pt
CL
CH
CL-ML
1 14
1
PI
%Fines
•
BH-1
S-3
12.5 - 14.0
(OH) Very dark brown, organic SILT
81
120
73
47
MZ1 SW 27th Street Culvert Replacement PLASTICITY CHART
HWAGEOSCIENCES INC. Renton, Washington
PROJECT NO.: 98032 FIGURE: g-1
HWAATTB 98032 1011/98
U.S. STANDARD SIEVE SIZES
3/4"
3" 1-1/2" 15/8" 3/8" #4 #10 #20 #40 #60 #100 #200
100
90
80
i-
2
70
W
} 60
m
W 50
Z
U-
I,— 40
Z
w
M 30
LU
0_
20
10
0
50 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001 0.0005
GRAIN SIZE IN MILLIMETERS
RAVEL
RAVEL
SAND
SILT
CLAY
i
1 1
1
I
1
1
I
1
1
1 I
I
I
1
1
I
1
1
1
I 1
I
I
I
I
1
1
1
1-r
I
I 1
I
I
I
1
I
I
I
1 I
1
I
1
1
I
I
1
I
t 1
1
1
1
I
1
1
1
1
1 I
1
1
1
1
1
1
1
1 i
I
1
I
I
I
I
i
1
1 1
1
I
I
I
I
1
i
I
I I
1
1
1
I
I
1
I
1
I I
I
1
1
I
I
1
1
1
I I
I
1
I
I
1
1
1
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1 I
I
I
I
I
I
1
1
I
1 I
1
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I
I
1
1
1
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I 1
I
I
I
I
I
1
I
I
I 1
1
1
I
I
I
1
I
1 1
1
I
t
I
I
1
1
I
1 1
1
1
I
1
I
I
i
I
1 1
I
I
1
1
I
I
I
I
I I
I
1
I
1
I
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1
1
I 1
I
1
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1
1
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1
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1
1
I 1
1
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I
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1
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1
1
1
1
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1 I
1 1
I
1
1
I
I
1
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I
1
1
1
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1
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1
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1
SYMBOL SAMPLE DEPTH (ft) CLASSIFICATION % MC LL PL PI %Gravel %Sand °,6 Fines
• BH-1 S-6 27.5 - 29.0 (ML) Very dark brown, sandy SILT 30 77.9
■ BH-1 S-7 32.5 - 34.0 ISM) Very dark grayish brown, very silty SAND 29 49.7
♦ BH-1 S-9 42.5 - 44.0 ISM) Very dark gray, silty SAND 22 1.0 85.1 13.9
GRAIN SIZE
a1
"T"ASW 27th Street Culvert Replacement DISTRIBUTION
HWAGEOSCIENCES INC. Renton, Washington TEST RESULTS
PROJECT NO.: 98032 FIGURE: B-2
HWAGRSZ 98032 10/1/98
GRAIN SIZE
a1
"T"ASW 27th Street Culvert Replacement DISTRIBUTION
HWAGEOSCIENCES INC. Renton, Washington TEST RESULTS
PROJECT NO.: 98032 FIGURE: B-2
HWAGRSZ 98032 10/1/98
7771--
U.S. STANDARD SIEVE SIZES
3/4"
3"
1-1/2" 15/8" 3/8" #4 #10 #20 #40 #60 #100 #200
100
—
90
80
70
60
W 50
z
LL
40
z
W
U
30
a.
20
10
50 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001 0.0005
GRAIN SIZE IN MILLIMETERS
GRAVEL
SAND
SILT
CLAY
Coarse
Fine
Coarse
Medium
Fine
SYMBOL
SAMPLE
DEPTH (ft)
CLASSIFICATION
% MC
LL
PL
PI
%Gravel
°h Sand
%Fines
•
■
BH-2
BH-2
S-5
S-8
22.5 - 24.0
37.5 - 39.0
(ML) Very dark grayish brown, very sandy SILT
(SM) Very dark gray, silty SAND
37
24
0.0
1.1
38.6
77.5
61.4
21.4
GRAIN SIZE
1
a "T"A
SW 27th Street Culvert Replacement DISTRIBUTION
HWAGEOSCIENCES INC. Renton, Washington TEST RESULTS
PROJECT NO.: 98032 FIGURE: B-3
HWAGRSZ 98032 10/1198