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1 GEOTECHNICAL REPORT
OLYMPIC PIPELINE CULVERT REPLACEMENT
SW 23RD STREET AND LIND AVENUE
RENTON, WASHINGTON
HWA Project No. 8919-100
1 May 11, 1998
1
Prepared for:
R.W. Beck
U LTU"A" 1
HWAGEOSCIENCES INC.
U ,
HWAGEOSCIENCES INC.
1 19730-64TH AVE. W., SUITE 200
LYNNWOOD, WA 98036-5957
' May 11 1998 TEL. 425-774-0106 y FAX.425-774-2714
HWA Project No. 8919-100 E-MAIL hwa@hongwest.com
' R.W. Beck
1001 Fourth Avenue, Suite 2500
Seattle, Washington 98154
Attention: Mr. Michael Giseburt, P.E.
Subject: OLYMPIC PIPELINE CULVERT REPLACEMENT
SW 23 d Street and Lind Avenue
Renton, Washington
' Dear Mr. Giseburt:
' Pursuant with your request, HWA GeoSciences Inc. (formerly Hong West & Associates)
performed a geotechnical engineering study for the proposed Olympic Pipeline Culvert
Replacement project in Renton, Washington. The results of our study are presented in the
accompanying report. A draft of this report, dated July 10, 1997, was originally submitted
to the City of Renton and R.W. Beck for review. The following report has been revised to
include the review comments.
We appreciate the opportunity to provide geotechnical services on this project. Should
you have any questions or comments, or if we may be of further service, please call.
Sincerely,
HWA GEOSCIENCES INC.
-�1 1
' David L. Sowers, P.E. Scott L. Hardman, P.E.
Geotechnical Engineer Senior Geotechnical Engineer
' DLS:SLH:dls
1 GEOLOGY
GEOENVIRONMENTAL SERVICES
1 HYDROGEOLOGY
GEOTEC HNICAL ENGINEERING
TESTING & INSPECTION
' TABLE OF CONTENTS
' Page
1.0 INTRODUCTION................................................................................................ 1
1.1 GENERAL .................................................................................................. 1
' 1.2 PROJECT DESCRIPTION............................................................................... 1
2.0 FIELD AND LABORATORY INVESTIGATION............................................... 2
' 2.1 FIELD INVESTIGATION................................................................................ 2
2.2 LABORATORY TESTING.............................................................................. 2
3.0 GEOLOGIC AND SUBSURFACE CONDITIONS.............................................. 2
' 3.1 GENERAL GEOLOGIC CONDITIONS.............................................................. 2
3.2 SUBSURFACE CONDITIONS......................................................................... 3
3.3 GROUNDWATER CONDITIONS..................................................................... 3
4.0 CONCLUSIONS AND RECOMMENDATIONS................................................. 4
4.1 GENERAL.................................................................................................. 4
' 4.2 SEISMIC DESIGN PARAMETERS................................................................... 5
4.3 EXCAVATIONS AND TEMPORARY SHORING................................................ 5
4.3.1 Unsupported Sloped Excavations................................................ 6
' 4.3.2 Temporary Shoring..................................................................... 6
4.4 GROUNDWATER CONTROL/DEWATERING................................................... 7
4.5 BOX CULVERT STRUCTURE........................................................................ 9
4.5.1 Subgrade Preparation and Foundation Support........................... 9
4.5.2 Lateral Earth Pressures............................................................... 10
' 4.5.3 Estimated Settlement.................................................................. 11
4.6 24-INCH DIAMETER CULVERT.................................................................... 11
4.7 BACKFILL PLACEMENT AND COMPACTION ................................................. 12
' 5.0 UNCERTAINTIES AND LIMITATIONS ........................................................... 13
6.0 REFERENCES .................................................................................................... 15
' LIST OF FIGURES(FOLLOWING TEXT
Figure 1. Vicinity Map
' Figure 2. Site and Exploration Plan
Figure 3. Earth Pressures for Temporary Shoring
Figure 4. Lateral Earth Pressures for Permanent Structures
' Appendix A: Field Exploration
Figure A-1. Legend of Terms and Symbols Used on Exploration Logs
' Figure A-2. Log of Boring BH-1
Appendix B: Laboratory Investigation
' Figure B-1. Grain Size Distribution Test Results
1
' GEOTECHNICAL REPORT
OLYMPIC PIPELINE CULVERT REPLACEMENT
SW 23RD AVENUE AND LIND AVENUE
' RENTON, WASMNGTON
1.0 INTRODUCTION
1.1 GENERAL
' This report presents the results of our geotechnical study for the proposed Olympic
Pipeline Culvert Replacement project in Renton, Washington. The purpose of this study
' was to explore and evaluate the surface and subsurface conditions at the site, and provide
geotechnical recommendations for design and construction of a concrete box culvert to
replace two existing metal culverts. In addition, we address geotechnical issues for
construction of a proposed 24-inch diameter culvert to be constructed along the east side
of Lind Avenue. A summary of our findings and evaluation of site conditions is presented
in this report.
' A proposal for the performance of this eotechnical investigation was submitted by HWA
P P P g
to R.W. Beck, dated May 2, 1997. Authorization to proceed with this scope of work was
' subsequently given by R.W. Beck in a subconsultant agreement dated June 18, 1997. The
scope of work completed for the project, as described herein, was in general agreement
' with that outlined in the Subconsultant Agreement.
1.2 PROJECT DESCRIPTION
' Our understanding of the Olympic Pipeline Culvert Replacement project is based on
discussions with and information provided by Mr. Scott Woodbury with the City of
' Renton, and Mr. Mike Giseburt of R.W. Beck.
The existing and proposed culverts are shown on Figure 2. Presently, surface water flows
through two, 80-foot long, 18-inch diameter metal culverts towards a small pond
immediately west of Lind Avenue. The proposed culvert replacement project will involve
' removing the two existing culverts and replacing them with a single 10-foot wide by 4-
foot high (inside dimensions) pre-cast concrete structure approximately 80 feet long. Wall
thickness is anticipated to be about 8 inches. In the vicinity of the proposed replacement
' culvert are several other utilities, including a Seattle Water Department water line and
three Olympic Pipeline petroleum pipelines.
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' May 11 1998
HWA Project No. 8919-100
As part of the project improvements, a new 24-inch diameter culvert will be installed
' which crosses SW 23rd Street on the east side of Lind Avenue. A manhole is planned as
part of the culvert installation so that the pipe can"step" around existing utilities.
' 2.0 FIELD AND LABORATORY INVESTIGATION
' 2.1 FIELD INVESTIGATION
On June 20, 1997, a geotechnical engineer from HWA logged the drilling of one 39-foot
deep boring (131-1-1) at the approximate location shown on the Site and Exploration Plan,
' Figure 2. The boring was performed to evaluate the presence and depth to groundwater,
and soil conditions at the site. The boring was drilled with a track-mounted Mobile drill
rig, owned and operated by Holocene Drilling of Pacific, Washington under subcontract to
HWA. Appendix A presents additional information regarding field exploration methods.
As part of the exploration program, HWA personnel recorded pertinent information
including soil sample depths, stratigraphy, soil engineering characteristics, and
groundwater occurrence. Soils were classified in the field in general accordance with the
' classification system described on Figure A-1. A key to the exploration log symbols is
also presented on Figure A-1. The boring log is presented on Figure A-2.
2.2 LABORATORY TESTING
Soil samples obtained at selected intervals within the boring were placed in air-tight bags
' and taken to our laboratory for further examination and testing. Select soil samples were
tested for in situ moisture content and grain size distribution. Discussions of laboratory
' test methodology and test results are presented in Appendix B.
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
Quadrangle, King County, Washington (Mullineaux, 1965). The geologic map indicates
that the area is generally underlain by peat and alluvial deposits. Alluvium, or river-
deposited soils, typically consist of interbedded, discontinuous layers of sand, silt, clay,
and organic soils. Recent alluvium is typically unconsolidated and generally exhibits low
shear strength and high compressibility.
' Regional geologic information was also obtained from previous geotechnical studies in the
vicinity of the project (GeoEngineers, 1992; Hong Consulting Engineers, 1989). In
evaluating geotechnical issues for the project, we also relied on borings completed nearby
8919100.doc 2 HWA GEOSCIENCES INC.
' May 11 1998
HWA Project No. 8919-100
for the ongoing SW 23`d Street Drainage Channel Deepening project. Results of
' explorations completed for that project will be presented in a forthcoming report.
' 3.2 SUBSURFACE CONDITIONS
Based on the results of our explorations, the site appears underlain by alluvial sands and
silts, consistent with the geologic map. Locally, the alluvium appears overlain by fill soils
' used to backfill the existing utilities and construct the access road. The subsurface units
encountered in the explorations are described below in the order of stratigraphic sequence
' in which they were deposited, with the youngest units described first:
• Fill: Fill materials were observed extending about 5 feet below the ground surface.
The fill soils generally consisted of loose, poorly graded sand with silt, with interbeds
' of silt and clay with organic matter. In our opinion, these fill materials were used to
construct the Seattle Water Department's access road and for backfill of the water
' line. The proposed location of the new culvert is off the edge of this access road, and
consequently we do not anticipate these fill materials will be encountered along the
proposed culvert alignment. Some fill soils may be encountered, associated with the
' existing Olympic Pipeline petroleum lines which cross the proposed culvert alignment.
• Alluvium: Alluvial soils were encountered directly beneath the fill in boring BH-1.
' The alluvium consisted generally of interbedded, very loose to medium dense sand and
silty sand, to very soft to very stiff silt with varying amounts of sand. The alluvium
' extended to the full depth of the boring.
Although extensive deposits of peat and organic soils are common in the Duwamish
Valley, significant layers of such materials were not encountered in the boring conducted
on site. However, this does not preclude the possible presence of organic soils and peat in
localized areas under the culvert alignments.
3.3 GROUNDWATER CONDITIONS
' Groundwater seepage was observed in the exploration at a depth of 5 feet below the
existing ground surface (approximately Elevation 11 feet). Seepage was observed during
drilling near the contact between the fill materials and the underlying alluvium deposit.
Standing water was observed in wetland areas at the project site. It is anticipated that
groundwater conditions will change in response to rainfall, time of year, and other factors.
' 8919100.doc 3 HWA GEOSCIENCES INC.
' May 11, 1998
' HWA Project No. 8919-100
4.0 CONCLUSIONS AND RECOMMENDATIONS
' 4.1 GENERAL
We understand that the invert elevation of the box culvert will be at approximately
' Elevation 6.5 feet (based on datum NAVD88) and that the invert elevation of the 24-inch
diameter culvert will be from Elevation 8 to 9 feet. At the time of our field investigation
' the groundwater level was observed at 5 feet below the existing ground surface, or about
Elevation 11 feet.
' We recommend implementing construction dewatering measures before excavating 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. We anticipate
dewatering can be accomplished using a combination of sumps and wellpoints. Use of
deep wells would also be feasible to facilitate dewatering. However, use of deep wells
' would result in groundwater drawdown over a larger area, which would produce greater
dewatering related settlements to adjacent structures.
' As proposed, installation of the proposed culverts will involve conventional open cuts.
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. The use of sheet piling to shore
excavations may be necessary in areas where dewatering and excavations would otherwise
impact existing utilities and roadways.
' Based on the conditions encountered in our exploration, the proposed box culvert is
underlain by soils capable of supporting the anticipated structural loads. We anticipate
that the weight of the new structure will be slightly greater than the weight of soil replaced
by the structure. Consequently, settlement on the order of 1 inch is anticipated from the
' additional loads.
Before placing the new concrete box culvert, subgrade preparation at the invert elevation
' may require placing a slab of lean concrete, or tremie slab, where loose, saturated soils are
encountered. If these subgrade soils are dewatered, a working pad of crushed rock could
be used instead. Some overexcavation of the subgrade will be required to place either the
' tremie slab or crushed rock pad. Additional overexcavations may be needed if highly
organic soils or peat are encountered at subgrade elevations.
Geotechnical recommendations for seismic design, excavations and temporary shoring,
groundwater control/dewatering, box culvert structure design, and backfill placement and
' compaction are discussed in further detail in the following sections.
' 8919100.doc 4 HWA GEOSCIENCES INC.
' May 11, 1998
' HWA Project No. 8919-100
4.2 SEISMIC DESIGN PARAMETERS
' The project alignment lies within Seismic Zone 3 as defined by the Uniform Building Code
(UBC, 1994). 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 pipeline. 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.
Detailed evaluation of soil liquefaction potential is beyond the scope of our work. Based
on our previous experience with similar soil conditions in Western Washington, the
' liquefaction potential of site soils is considered moderate to high during a strong seismic
event. In particular, loose sandy soil layers beneath the site are susceptible to liquefaction.
' Potential effects of soil liquefaction include temporary loss of bearing capacity,
liquefaction-induced settlement, and lateral spreading, which could result in damage to the
proposed culvert. It should be noted that the site is anticipated to have no greater seismic
' risk than surrounding developments. While the proposed culvert construction will not
mitigate the potential for seismic-induced liquefaction, installation of the culvert is not
anticipated to increase seismic risk or soil liquefaction potential at the site.
i
4.3 EXCAVATIONS AND TEMPORARY SHORING
' We understand conventional open excavations will be the primary method for installation
of the replacement culverts. Excavations are anticipated to have maximum depths on the
' order of 10 feet below the existing ground surface along the box culvert alignment, and
approximately 12 feet below the existing ground surface along the 24-inch culvert
alignment. We anticipate excavations for the culvert can be accomplished with
conventional equipment such as backhoes and trackhoes.
Excavation and construction of the new culverts must be performed in a manner which
' will not impact existing utilities. Shoring may be required in areas where the excavations
encroach upon the utilities. Temporary support and protection of the Olympic Pipeline
petroleum lines and other utilities must be provided and maintained during construction.
' This may require the use of struts or saddles to temporarily support the existing utilities
and minimize sagging. 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.
' 8919100.doe 5 HWA GEOSCIENCES INC.
tMay 11, 1998
' HWA Project No. 8919-100
Recommendations for unsupported sloped excavations and temporary shoring are
' presented in the following sections.
' 4.3.1 Unsupported Sloped Excavations
Maintenance of safe working conditions, including temporary excavation stability, is the
responsibility of the contractor. All temporary cuts in excess of 4 feet in height should be
' sloped in accordance with Part N of WAC (Washington Administrative Code) 296-155 or
shored. The existing fill and native sands and silts are generally classified as Type C soil.
' Excavations in Type C soils should be inclined no steeper than 1'/2H:1 V
(horizontal:vertical). The recommended allowable cut slope inclinations are 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.
4.3.2 Temporary Shoring
' Sheet pile walls are considered suitable for temporary support of excavations in areas
where open-cut excavations are not feasible or where additional support is required for
protection of existing utilities. General recommendations for design and implementation
of shoring systems for the project are presented below.
t • Design parameters for sheet pile walls used along the pipeline alignment are shown
on Figure 3. Such sheet pile walls should be designed and constructed to support an
equivalent fluid pressure of 21 pounds per cubic foot (pcf), plus hydrostatic water
' pressure (unit weight of water equal to 62.4 pcf). If the groundwater level is not at
the ground surface behind the excavation, then"H" is reduced to the effective height
' of water in the hydrostatic pressure equation. These recommended values assume
that groundwater will be drawn down from within sheet pile supported areas.
' • Surcharge loads from construction equipment, construction materials, excavated
soils, or vehicular traffic should be included in the shoring design.
' • To minimize the potential for excessive sheet pile deflections, use of horizontal
bracing may be needed to provide additional lateral support.
1
' 8919100.doc 6 HWA GEOSCIENCES INC.
' May 11, 1998
HWA Project No. 8919-100
• Precautions should be taken during removal of the shoring or sheeting materials to
' minimize disturbance to the culvert and underlying materials, underlying bedding
materials, natural soils, and adjacent utilities.
' Trench boxes may be used to facilitate installation of the 24-inch diameter culvert. Trench
boxes should be adequately reinforced to withstand the lateral forces to which they will be
subjected. Trench boxes should be of sufficient size, both vertically and laterally, to
' support the excavation without excessive deformation of the natural soils.
Where a trench box is used to support excavations in the alluvial soils, one or both sides of
' the trench is likely to cave against the box. The caving may extend out on either side of
the trench for a distance approximately equal to the depth of the trench. Additional
' bracing or sheeting may be required where the near edge of the trench will be closer than
about 1.5 times the trench depth to settlement sensitive structures or utilities. The open
excavation behind the trench box should be backfilled as soon as practical after the trench
' box has been moved.
' 4.4 GROUNDWATER CONTROL/DEWATERING
Results of the field exploration program indicate that groundwater will be encountered
during construction of the replacement box culvert and new 24-inch diameter culvert.
Therefore, the need for temporary construction dewatering should be anticipated. Based
on the soils encountered and the proposed depth of excavations (see Section 4.1), it is our
' opinion that dewatering can be accomplished using wellpoints and sumps. It is the
contractor's responsibility to design, construct, and maintain an effective dewatering
system. Prior to construction, the contractor should determine an appropriate dewatering
' scheme and submit a dewatering plan to the project engineer for review. For preliminary
planning and costing purposes, the following general assessments are provided.
' Use of conventional wellpoints is considered appropriate for areas where soft silt with
sand deposits are present. For open-cut excavations, we estimate wellpoints on 2'h- to 5-
foot centers around the perimeter of the excavation will be required. Wellpoints should
' extend 15 to 20 feet deep. Sumps may be used in conjunction with the wellpoints,-
however, we consider it unlikely that dewatering can be accomplished entirely using
' sumps. Another alternative for construction dewatering is the use of deep wells. We
estimate 25-foot deep wells installed at 20 feet on center would be required, as a
minimum.
' Groundwater seepage into the open excavation will tend to destabilize side slopes and
increase lateral loads on 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 excavating and construction of the
8919100.doc 7 HWA GEOSCIENCES INC.
May 11, 1998
' HWA Project No. 8919-100
culvert 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.
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, we estimate that for a 7-foot deep open-cut excavation, 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'/z to 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, 40 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.
The extent of dewatering-related groundwater drawdown should be monitored during
construction to minimize the potential for settlement damage. A contingency should be
provided for installation of recharge wells should the dewatering system result in
significant lowering (e.g. 5 feet or more) of groundwater levels beneath the existing
utilities and roadways.
' An option to dewatering the site which will help minimize settlement of existing utilities
and roadways would be to construct the proposed structure(s) in a"wet" or submerged
condition. A potential difficulty with placing the structure in a submerged condition is that
' the foundation subgrade is difficult to prepare and can not be evaluated visually during
construction. We anticipate maximum settlements of approximately 1 inch due to the
increase in load if construction is performed under dry conditions, and subgrade
disturbance is minimized. However, if construction occurs in a submerged condition, we
anticipate total maximum settlements would be on the order of 2 to 3 inches, due to the
level of subgrade disturbance which may occur. Settlement of new structures and existing
' utilities is discussed further in Section 4.5.3.
8919100.doc 8 HWA GEOSCIENCES INC.
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HWA Project No. 8919-100
4.5 BOX CULVERT STRUCTURE
4.5.1 Subgrade Preparation and Foundation Support
Based on the results of our explorations, we anticipate very soft silt to very loose sand will
' be encountered at/near the proposed base of the box culvert. Before placing the box
culvert, we recommend stabilizing the subgrade with the use of either a crushed rock or
lean concrete working surface. Placement of a working surface will help to minimize
damage to the subgrade soil during placement of the box culvert. If a lean concrete
working surface is used, we anticipate the working surface will be useful to jack against
' for supporting existing utilities, or possibly bracing against for sheet pile walls, depending
on their configuration, as well as for sliding pre-cast sections beneath the existing
pipelines.
' A lean concrete working surface or tremie slab, can be poured directly on the subgrade in
either dry or wet conditions. The tremie slab is preferable to a crushed rock pad because
' the subgrade condition may be less than ideal and no compaction effort is required for the
lean concrete or controlled density fill (CDF) mix. If construction occurs in wet
' conditions, or underwater, it will be necessary to use a concrete tremie slab. The tremie
slab should be a minimum of 12 inches thick, requiring overexcavations extending into the
subgrade a similar depth.
' Crushed rock is an acceptable alternative to the tremie slab providing construction occurs
under dry conditions. The crushed rock pad should be a minimum of 24 inches thick, and
' would require overexcavating the subgrade a similar depth.
Although peat and highly organic soils were not encountered at anticipated subgrade
' elevations in boring BH-1, regional geologic conditions and explorations from nearby
geotechnical studies indicate the potential for discontinuous lenses and layers of peat and
' organic soils. In the event that soft, compressible soils are encountered at the anticipated
subgrade elevation for the tremie slab/crushed rock pad, the unsuitable soils should be
overexcavated and replaced. A geotextile fabric may be used below the tremie
slab/crushed rock pad if soft, organic soils are encountered at the bottom of the
overexcavation. In this case, use of the geotextile may help reduce the amount of required
overexcavation, but would not eliminate the need to overexcavate. The overexcavation
tprocess, if necessary, should be observed by the geotechnical consultant. The
overexcavated area should be backfilled with structural fill as described in Section 4.7.
' If the subgrade is prepared as described above, the alluvial sands and silts are anticipated
to provide adequate foundation support. For design purposes, we recommend an
' allowable soil bearing pressure of 1,000 pounds per square foot (psf) for use in design of
8919100.doc 9 HWA GEOSCIENCES INC.
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' HWA Project No. 8919-100
the culvert structure (our calculations indicate that the increase in load of the new
structure will be less than 1,000 psf).
t 4.5.2 Lateral Earth Pressures
Lateral earth pressures against below-grade structures will depend upon the inclination of
any adjacent slopes, type of backfill, degree of wall restraint, method of backfill
' placement, degree of backfill compaction, drainage provisions, and magnitude and location
of any surcharge loads. At-rest soil pressure is exerted on a subsurface structure or wall
' when it is restrained against rotation.
For this project, it is anticipated that the proposed structural walls will be restrained
' against rotation and will have relatively level backfill. As such, the box culvert should be
designed for a horizontal at-rest equivalent fluid pressure of 52 pounds per cubic foot
(pcf) above the design groundwater elevation and 87 pcf below the design groundwater
' elevation. The value of 87 pcf includes hydrostatic pressure. The configuration of the
earth pressures generated is shown on Figure 4.
The above recommendations regarding at-rest earth pressures assume 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 structures will be subjected to the
influence of surcharge loading within a horizontal distance equal to or less than the height
of the walls, the walls should be designed for the additional horizontal pressure using a
suitable method for modeling surcharge loads.
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.
' Winds earthquakes, and unbalanced earth and water loads subject structures to lateral
q
' forces. Lateral forces on a structure will be resisted by a combination of sliding resistance
of its base or footing on the underlying soil and passive earth pressure against the buried
portions of the structure, as shown on Figure 4. The sliding resistance of cast-in-place
' concrete on structural fill may be calculated using a coefficient of friction of 0.4.
' 8919100.doc 10 HWA GEOSCIENCES INC.
May 11, 1998
' HWA Project No. 8919-100
4.5.3 Estimated Settlement
The likely mechanisms for settlement are from poor bearing support immediately below
the box culvert, or consolidation of underlying compressible soils under new loads.
' Bedding the culvert structure in accordance with the recommendations described above,
including removal of soft and/or organic soils from below the alignment, will help reduce
' the potential for differential settlement. We anticipate the culvert and backfill will weigh
slightly more than the soil it displaces. While this pressure increase is minor, settlement of
the structure will also depend in part on the contractor's methods and the amount of
' subgrade disturbance which occurs during construction.
Based on the conditions of the site and the extent of site preparation that will be required
' for this project, some disturbance to subgrade soils should be expected. 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 due to
the increase in load may be less 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 to 3 inches, as
described in Section 4.4.
' Settlement from construction of the new box culvert will impact the supporting backfill
soils around the existing Olympic pipelines. Evaluations should be performed to verify
fthat 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 or lean concrete.
' 4.6 24-INCH DIAMETER CULVERT
The project includes construction of the new 24-inch culvert along the east side of Lind
Avenue. The new culvert will connect the drainage swale on the north side of the SW 23`d
' Street to the wetland area on the south side of the roadway. As proposed, the new culvert
will intersect several utilities which parallel SW 23`d Street, crossing beneath two fiber
' optic lines and two Olympic pipelines, and crossing over the City of Seattle's 60-inch
' 8919100.doc 11 HWA GEOSCIENCES INC.
May 11, 1998
HWA Project No. 8919-100
diameter waterline. A manhole will be used to accommodate the grade change of the
' culvert and facilitate crossing the existing utilities.
Our explorations in the project vicinity indicate that shallow groundwater will be
encountered during culvert and manhole installation. We anticipate trench boxes or steel
sheets can be used to shore the excavation. As described in Section 4.4, the method of
construction, dry or wet, will determine the amount of settlement adjacent utilities and
' roadways could exhibit. If construction takes place in dry conditions, dewatering should
be performed within shored excavations so that nearby utilities are not impacted by
groundwater level drawdown; in particular the City of Seattle 60-inch water line, which is
especially sensitive to ground movement. An option to dewatering in this area, and one
which would be less detrimental to utilities and which was discussed for the box culvert,
' would be to construct the 24-inch culvert in submerged conditions. Depending on the
method of construction selected, the contractor should submit a plan for temporary
support of the existing utilities during construction, for review prior to construction.
' We anticipate loose sand/silty sand and soft to stiff silt will be encountered at/near the
base of the proposed culvert. We anticipate these soils should provide adequate support
' of the proposed culvert, providing they are not disturbed during subgrade preparation.
Providing the sands and silts are not laden with organic matter, the culvert sections can be
' placed directly on the exposed subgrade; no bedding soil is necessary. If very soft,
organic-rich subgrade soils are present at the subgrade elevation of the culvert or subgrade
soils are unduly disturbed, it may be necessary to over-excavate these unsuitable materials
' and backfill with more suitable materials. We recommend over-excavating and backfilling
the soft soils to a maximum depth of 2 feet below the pipe invert with crushed rock.
' Materials meeting the specification for pipe bedding, as described in Section 9-03.15 of
the 1998 W SDOT Standard Specifications for Road, Bridge, and Municipal Construction
(WSDOT Standard Specifications), should be used to backfill around the culvert to a
' depth of at least 6 inches above the top of the pipe for the full width of the trench. Pipe
bedding material, placement, compaction, and shaping should be in accordance with the
' project specifications and the pipe manufacturer's recommendations.
Placement and compaction of backfill materials placed in the trench above the pipe
' bedding is discussed in the following section.
4.7 BACKFILL PLACEMENT AND COMPACTION
All materials used for backfilling overexcavations of unsuitable soils, and used for the
crushed rock working surface 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. Materials used to backfill excavations for the box culvert and
8919100.doc 12 HWA GEOSCIENCES INC.
' May 11, 1998
HWA Project No. 8919-100
24-inch diameter 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 soils contain a high percentage of fine-
grained material and are generally too wet for compacting. Consequently, it is our opinion
that soils encountered during excavating will not be suitable for reuse as backfill. The
excavated soils may be used in areas where some settlement can be tolerated, such as
' landscaping areas.
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
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 and potential
' impacts of such settlement on the existing utilities, it is 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.
It is imperative that the contractor protect the existing pipelines during placement and
compaction of backfill soils around the culverts.
' 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 and
1
8919100.doc 13 HWA GEOSCIENCES INC.
' May 11 1998
HWA Project No. 8919-100
shoring systems, excavation, subgrade preparation, bedding and backfill placement and
' compaction.
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'O
We appreciate this opportunity to be of service.
' Sincerely,
' HWA GEOSCIENCES INC.
' �1U so({.� ,t L. HA
crsr
' EXPIRES 1EXPIRES I i
' David L. Sowers, P.E. Scott L. Hardman, P.E.
Geotechnical Engineer Senior Geotechnical Engineer
t
' 8919100.doc 14 HWA GEOSCIENCES INC.
May 11 1998
' HWA Project No. 8919-100
6.0 REFERENCES
GeoEngineers, 1992,Report, Geotechnical Engineering Services, Proposed Puget
' Western Business Park, Renton, Washington, consultant report prepared for Puget
Western, Inc., dated March 27, 1992.
' Hong Consulting Engineers, Inc., 1989, Geotechnical Soil Investigation, Panther Creek,
SR 167—P-9 Channel Project, Renton, Washington, consultant report prepared for
R.W. Beck, dated June 2, 1989.
' Mullineaux, D.R., 1965, Geologic Map of the Renton Quadrangle, King County,
Washington, U. S. Geological Survey.
Uniform Building Code, 1994, Structural Engineering Design Provisions, published by the
International Conference of Building Officials, Vol. 2, 1339 p.
' Washington State Department of Transportation/American Public Works Association,
1998, Standard Specifications for Road, Bridge, and Municipal Construction.
' 8919100.doc 15 HWA GEOSCIENCES INC.
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1�' , OLYMPIC PIPELINE VICINITY MAP
' Y CULVERT REPLACEMENT
HWAGEOSCIENCES INC RENTON, WASHINGTON
PROJECT NO.:8919-100 FIGURE: 1
' D: S 100\8919001.DWO
9 01.
tASSUME GROUNDWATER
AT GROUND SURFACE
' FOR DESIGN —
�k\
' CANTILEVERED SHEET PILE WALL OR
SHEET PILE WALL WITH ONE LEVEL
OF BRACING
' BRACING/STRUT
H
1
' BOTTOM OF EXCAVATION '
2' 2' GROUNDWATER DRAW
' T DOT EXCAVATION
' D
t
62.4(H+2) 21(H+D) 24OD
' ULTIMATE
HYDROSTATIC ACTIVE EARTH PASSIVE EARTH
PRESSURE PRESSURE PRESSURE
1
' 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 dewatering to surrounding areas.
4. Surcharge loads should be added to the active pressure where
appropriate.
' S. A factor of safety has not been applied to the recommended
earth pressure values.
6. All units in feet and pounds.
OLYMPIC PIPELINE EARTH PRESSURES FOR
IF01' CULVERT REPLACEMENT TEMPORARY SHORING
HWAGEOSCIENCESINC RENTON, WASHINGTON
' PROJECT NO.:8919-100 FIGURE: 3
C: JOBS 8919-100 8919003.OWG
STRUCTURE
DESIGN GROUNDWATER IH1
LEVEL
+ H 2 +
1
e G - .°
' 62.4H 2 25H 2 5211 1 0.4 x NORMAL FORCE 295H1 142H2 62.41-12
AT-REST SLIDING PASSIVE
' EARTH PRESSURES RESISTANCE RESISTANCE
' NOTES
1, H1 AND H2 MEASURED IN FEET; EQUIVALENT FLUID WEIGHT IN POUNDS PER CUBIC FOOT (pcf).
' 2. RECOMMENDED PASSIVE RESISTANCE AND FRICTION FACTOR INCLUDE A FACTOR OF SAFETY OF ABOUT 1.5.
3. EARTH AND HYDROSTATIC PRESSURES SHOULD BE COMBINED BELOW THE DESIGN GROUNDWATER LEVEL.
' 4. REFER TO REPORT TEXT FOR DISCUSSION OF DESIGN GROUNDWATER LEVEL.
5. RECOMMENDED EARTH PRESSURES ASSUME PROPERLY COMPACTED STRUCTURAL FILL ADJACENT TO
' STRUCTURES.
' ASSUMPTIONS
TOTAL SOIL UNIT WEIGHT = 120 pcf
' BUOYANT SOIL UNIT WEIGHT = 57.6 pcf
UNIT WEIGHT OF WATER = 62.4 pcf
' SOIL FRICTION ANGLE = 35"
SOIL/CONCRETE FRICTION ANGLE = 30-
1
1 OLYMPIC PIPELINE LATERAL EARTH PRESSURES
CULVERT REPLACEMENT FOR PERMANENT STRUCTURES
HWAGEOSCIENCESINC. RENTON, WASHINGTON
' PROJECT NO.:891 9-1 00 FIGURE: 4
C: J08S 8919-100 8919004.DWG
' APPENDIX A
' FIELD EXPLORATION
' APPENDIX A
' FIELD EXPLORATION
The field investigation consisted of drilling and sampling one exploratory boring, to a
' maximum depth of approximately 39 feet. The field exploration program was completed
on June 20, 1997 under the full-time observation of an HWA engineer. The boring was
' located approximately in the field by taping distances from known site features and plotted
on the Site and Exploration Plan, Figure 2. A legend to the terms and symbols used on
the exploration logs is presented on Figure A-1. A summary boring log is presented on
Figure A-2.
Geotechnical drilling was performed by Holocene Drilling of Pacific, Washington, under
' subcontract to HWA. The boring was drilled with a Mobile track-mounted drill rig
advancing a 4'/4-inch I.D., continuous flight hollow stem auger.
' During drilling, the HWA representative recorded pertinent information including soil
sample depths, stratigraphy, soil engineering characteristics, and groundwater occurrence.
' The stratigraphic contacts shown on the boring log represent the approximate boundaries
between soil types, actual transitions may be more gradual. The soil and groundwater
conditions depicted are only for the specific date and location reported, and therefore, are
' not necessarily representative of other locations and times.
At intervals within the boring, Standard Penetration Test (SPT) sampling was performed
' in general accordance with ASTM D-1586 using a 2-inch outside diameter split-spoon
sampler and a standard 140-pound hammer. During the test, a sample is obtained by
driving the sampler 18 inches into the soil with a hammer free-falling 30 inches per stroke.
' The number of blows required for each 6 inches of penetration is recorded. The SPT
Resistance ("N-value") of the soil is calculated as the number of blows required for the
final 12 inches of penetration. The N-value provides a measure of the 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 air-tight
plastic bags. These soil samples were then returned to our Lynnwood, Washington
laboratory for further examination and testing.
' 8919100.doc A-1 HWA GEOSCIENCES INC.
RELATIVE DENSITY OR CONSISTENCY VERSUS SPT N-VALUE TEST SYMBOLS
COHESIONLESS SOILS COHESIVE SOILS %F Percent Fines
Approximate AL Atterberg Limits: PL = Plastic Limit
Approximate LL = Liquid Limit
Density N(blows/ft) Consistency N(blows/ft) Undrained Shear q
Relative Density(%) Strength(psf) CBR California Bearing Ratio
Very Loose 0 to 4 0 15 Very Soft 0 to 2 <250 CN Consolidation
Loose 4 to 10 15 35 Soft 2 to 4 250 - 500 DO Dry Density (pcf)
Medium Dense 10 to 30 35 - 65 Medium Stiff 4 to 8 500 - 1000 DS Direct Shear
Dense 30 to 50 65 85 Stiff 8 to 15 1000 - 2000 GS Grain Size Distribution
Very Dense over 50 85 - 100 Very Stiff 15 to 30 2000 - 4000 K Permeability
Hard over 30 >4000 MD Moisture/Density Relationship (Proctor)
' MR Resilient Modulus
USCS SOIL CLASSIFICATION SYSTEM
PID Photoionization Device Reading
MAJOR DIVISIONS GROUP DESCRIPTIONS PP Pocket Penetrometer
Approx.Compressive Strength(tsf)
Gravel and ° 0 GW Well-graded GRAVEL SG Specific Gravity
Coarse Clean Gravel TC Triaxial Compression
Grained Gravelly Soils (little or no fines)
GP I Poorly-graded GRAVEL TV Torvane
Soils Approx. Shear Strength (tsf)
More than
50%of Coarse Gravel with GM Silty GRAVEL UC Unconfined Compression
Fraction Retained Fines(appreciable
on No.4 Sieve amount of fines) GC I Clayey GRAVEL SAMPLE TYPE SYMBOLS
Sand and Clean Sand
SW Well-graded SAND ® 2.0" OD Split Spoon (SPT)
Sandy Soils (little or no fines) (140 lb.hammer with 30 in.drop)
More than Sp Poorly-graded SAND
50%Retained Shelby Tube
50%or More
on No. y
Sand with SM Silt SAND
of Coarse � 3.0"OD Split Spoon with Brass flings
200 Sieve Fraction Passing Fines(appreciable
' Size No.4 Sieve amount of fines) SC Clayey SAND O p
Small BagSample
Fine Silt
ML SILT Large Bag (Bulk)Sample
Grained and Liquid Limit
Less than 50% N
CL Lean CLAY Core Run
Soils Clay =
OL Organic SILT/Organic CLAY � Non-standard Penetration Test
(with split spoon sampler)
MH Elastic SILT
' 50%or More Silt
Liquid Limit 11
Passing and Clay 50%or More CH Fat CLAY GROUNDWATER SYMBOLS
No.200 Sieve y
/ Q Groundwater Level (measured at
Size OH Organic SILT/Organic CLAY =
= time of drilling)Highly Organic Soils PT PEAT = Groundwater Level (measured in well or
open hole after water level stabilized)
COMPONENT DEFINITIONS COMPONENT PROPORTIONS
COMPONENT SIZE RANGE PROPORTION RANGE DESCRIPTIVE TERMS
Boulders Larger than 12 in
< 5°,6 Clean
' Cobbles 3 in to 12 in
Gravel 3 in to No 4(4.5mm) 5 - 12% Slightly (Clayey,Silty, Sandy)
Coarse gravel 3 in to 3/4 in
Fine gravel 3/4 in to No 4(4.5mm)
12 -30°,U Clayey,Silty,Sandy,Gravelly
' 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(2.0 mm)to No.40(0.42 mml 30-50% Very(Clayey,Silty,Sandy,Gravelly)
Fine sand No.40(0.42 mm)to No. 200(0.074 mm)
i Silt and Clay Smaller than No. 200(0.074mm) 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. Sod descriptions MOISTURE CONTENT
are presented in the following general order:
' DRY Absence of moisture,dusty,
Density/consistency,color,modifier(if any)GROUP NAME,additions to group name(if anyl,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
9601 Olympic Pipeline Culvert Replacement SYMBOLS USED ON
' HWAGEOSCIENCES INC Renton, Washington EXPLORATION LOGS
PROJECT NO.: 8919-100 FIGURE: A-1
' LEGEND 89191 4/18/98
' DRILLING COMPANY: Holocene LOCATION: See Figure 2
DRILLING METHOD: Track Mounted Mobile, 4-1/4" ID HSA DATE COMPLETED: 6/20/97
SURFACE ELEVATION: 16 t Feet LOGGED BY: David Sowers
' rn cc w
w
co Q w uj
Q r Standard Penetration Resistance
t Z S2 c W (140 lb. weight, 30" drop) m
-j O w w U)( 0 ♦ Blows per foot
w�
m d a cc 3 w D ~
n H < Z:o F- � w
' o N Q DESCRIPTION N (n o_— O 0 0 10 20 30 40 50
0 SP Loose, dark brown to dark reddish brown, 0
SM poorly graded SAND with silt, moist.
(FILL) S-1 1-2-3
t Interbeds of silt and clay with trace organics
5 Q ................... ............_ .. .. _ .. . _ . 5
ML Very soft to soft, dark gray, SILT with fine
' sand, wet.
(ALLUVIUM) S-2 1-1-2
Interbeds of fine to medium sand.
' 10
S-3 1/12"-1
SP Very loose, dark gray, poorly graded fine to
_............ ...... .. _ .. _ .. _ .. 10
- - -
- - - - - - - - - - - - - - - - - - - - - - _ ..
1 5 medium SAND, wet. ..- - 15
ML Very stiff, very dark gray sandy SILT, wet. Fine
' sand. S-4 6-11-8 GS
20 _............ ............_...... .. _ .. _ .. 20
' SM Loose, dark grayish brown, silty SAND, wet
Fine to medium sand. S-5 3-3-3 GS
' ...... .. ...... _...... 25
25
SP Medium dense, dark grayish brown, poorly
graded SAND, wet.Trace silt. Fine to coarse
sand. S-6 4-10-12
30 •......_...- ......_............_ .. .. _ .. ......_ .. 30
S-7 7-7-7
35 ...._............_
......:......
S-8 4-11-11
' Bottom of boring at 39 feet.
40
40 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.
Olympic Pipeline Culvert Replacement BORING: BH-1
' HWAGEOSCIENCES INC. Renton, Washington PAGE: 1 of 2
PROJECT NO.: 891 9-1 OO FIGURE: A-2
' BORING 89191 4/18/98
' APPENDIX B
' LABORATORY TESTING
' APPENDIX B
' LABORATORY TESTING
' HWA personnel performed laboratory tests in general accordance with appropriate ASTM
test methods. We tested selected soil samples from the exploratory borings to determine
moisture content and grain size distribution. The test procedures and test results are
' briefly discussed below.
' Moisture Content
Laboratory tests were conducted to determine the moisture content of selected soil
' samples, in general accordance with ASTM D-2216. Test results are indicated at the
sampled intervals on the boring log in Appendix A.
tGrain Size Distribution
Grain size distribution was determined for selected samples in general accordance with
' ASTM D-422. Results of these analyses are plotted on Figure B-1.
' 8919100.doc B-1 HWA GEOSCIENCES INC.
GRAVEL SAND SILT CLAY
Coarse Fine Coarse I Medium I Fine
U.S. STANDARD SIEVE SIZES
3/4"
3" 1-1/2" 1 5/8" 3/8" #4 #10 #20 #40 #60 #100 #200
100
90
80
2 70Uj
+
60
W 50 +—i
LL
F— 40
Uj
U 30
LLJ
CL
20
50 10 5 1 0.5 0.1 0.05 0.01 0.005 0.001 0.0005
GRAIN SIZE IN MILLIMETERS
SYMBOL SAMPLE DEPTH (ft) CLASSIFICATION % MC LL PL PI %Gravel % Sand % Fines
• BH-1 S-4 17.5 - 1 9.0 (ML)Very dark gray, sandy SILT. 24 0.4 36.3 63.3
■ BH-1 S-5 22.5 - 24.0 (SM) Dark grayish brown, silty SAND. 30 0.2 62.1 37.7
GRAIN SIZE
1
Olympic Pipeline Culvert Replacement DISTRIBUTION
HWAGEOSCIENCES INC. Renton, Washington TEST RESULTS
PROJECT NO.: 89 1 9-1 OO FIGURE: B-1
HWAGRSZ 89191 4/18/98
a