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Engineering
Design Study
Proposed SR106 Realignment
Geotechnical Engineering Design Study
Proposed SR 106 Realignment
(Long Extension Alternative)
Union, Washington
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North Forty Transportation, L.L.C.
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January 22, 2003
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Geotechnical Engineering Design Study
Proposed SR 106 Realignment
(Long Extension Alternative)
Union, Washington Boston
Denver
Prepared for
North Forty Transportation, L.L.C.
Edmonds
January 22, 2003
7747
Eureka
Prepared by
Hart Crowser, Inc.
Jersey City
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WrneC. dams, C.E.G. J. Jeffrey Wagner, P.E.Sciate Principal Portland
Hart Crowser,Inc. Seattle
Five Centerpointe Drive,Suite 240
Lake Oswego, Oregon 97035-8652
Fax 503.320.6918
TO 503.620.7284
CONTENTS Page
INTRODUCTION 1
PURPOSE, SCOPE, AND LIMITATIONS 1
Purpose 1
Scope of Geotechnical Services 2
Limitations of Our Work 2
PROJECT UNDERSTANDING 2
The Site 2
SR 106 Realignment 2
GENERALIZED SUBSURFACE CONDITIONS 3
Geologic Setting 3
Subsurface Soil Conditions 4
Abundant Surficial and Isolated Subsurface Perched Water 6
GEOTECHNICAL ENGINEERING CONCLUSIONS AND RECOMMENDATIONS 6
General Considerations 6
Site Preparation 7
Road Cut Slopes and Fill Support g
MSE Wall Design Considerations 10
Drainage and Seepage Control 11
Structural Fill 13
Pavement Design Considerations 16
CONSTRUCTION CONSIDERATIONS 17
RECOMMENDED ADDITIONAL GEOTECHNICAL SERVICES 17
REFERENCES 19
Geology 19
Aerial Photographs 19
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7747 January 22,2003
CONTENTS Page
FIGURES
1 Vicinity Map
2 Site and Exploration Plan
3 Generalized Subsurface Cross-Section A-A' (Station 112+20)
APPENDIX A
FIELD EXPLORATIONS METHODS AND ANALYSIS A-1
Explorations and Their Location A-1
The Use of Auger Borings A-2
Standard Penetration Test(SPT) Procedures A-3
The Use of Hand Auger Borings A-3
FIGURES
A-1 Key to Exploration Logs
A-2 through A-6 Observation Well Logs HC-B1 through HC-135
A-7 through A-9 Hand-Auger Boring Log HC-HA1 through HC-HA7
APPENDIX B
LABORATORY TESTING PROGRAM B-1
Soil Classification B-1
Water Content Determinations B-1
Grain Size Analysis (GS) B-1
Atterberg Limits (AL) B-2
FIGURES
B-1 Unified Soil Classification (USC) System
B-2 Particle Size Distribution Test Report
B-3 Particle Size Distribution Test Report
B-4 Liquid and Plastic Limits Test Report
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7747 January 22,2003
GEOTECHNICAL ENGINEERING DESIGN STUDY
PROPOSED SR 106 REALIGNMENT
(LONG EXTENSION ALTERNATIVE)
UNION, WASHINGTON
INTRODUCTION
This report presents the results of our subsurface explorations and geotechnical
engineering design study for the proposed State Route (SR) 106 realignment,
located about 1.5 miles east of Union, Washington.
We have organized this report into several distinct sections as follows:
■ Purpose, Scope, and Limitations;
■ Our Understanding of the Project;
■ Generalized Subsurface Conditions;
■ Geotechnical Engineering Conclusions and Recommendations;
■ Construction Considerations; and
■ Recommended Additional Geotechnical Services.
The field data are presented in Appendix A, and the laboratory data are
presented in Appendix B.
PURPOSE, SCOPE, AND LIMITATIONS
Purpose
The purpose of our work is to provide North Forty Transportation, L.L.C. and
their design consultants with geotechnical engineering recommendations related
to the design and construction of the proposed development. For this study, we
make specific recommendations regarding:
■ Site preparation;
■ Road cut slopes and fill support;
■ Drainage and seepage control measures;
■ Selection, placement, and compaction of structural fill;
■ Pavement design;
■ Construction considerations; and
■ Additional geotechnical services.
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7747 January 22,2003
Scope of Geotechnical Services
Our scope of work for this project included:
■ Reviewing existing site geologic information;
■ Reviewing site aerial photos (see References) for indications of landslide
activity;
■ Advancing five hollow-stem auger borings and seven hand-auger borings;
■ Performing geotechnical laboratory soil testing;
■ Formulating geotechnical engineering design recommendations, design
alternatives, and considerations; and
■ Producing this geotechnical engineering design report.
Limitations of Our Work
We completed this work in accordance with our proposal dated April 11, 2002,
and contract change dated January 6, 2003. Our report is for the exclusive use
of North Forty Transportation, L.L.C., and their design consultants for specific
application to the subject project and site. We completed this report in
accordance with generally accepted geotechnical practices for the nature and
conditions of the work completed in the same or similar localities, at the time
the work was performed. We make no other warranty, express or implied.
PROJECT UNDERSTANDING
The Site
The site is located about 1.5 miles east of Union, Washington, as shown on
Figure 1. The road realignment location (see Figure 2) crosses a portion of
moderately steep (25 to 35 degrees) alder-covered slope, with wet areas, seeps,
and springs along the realignment that will require cut and fill slopes. The
topography along the alignment ranges from about 30 to 80 feet in elevation.
SR 106 Realignment
The project consists of the proposed realignment of about 2,600 linear feet of
SR 106 with about 1,000 linear feet of highway cut slope and about 600 linear
feet of fill slopes or embankments.
At this stage in the design, we have considered several alternatives of
configuring the side slopes for the road including mechanically stabilized earth
(MSE) walls, permanent soil nail walls between Stations 109+00 and 113+00,
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7747 January 22,2003
permanent cut and fill slopes, and/or a combination of these alternatives. We
understand the design team is currently intending to use cut slopes, but MSE
walls may be used in fill areas. Therefore, in this report, we discuss general
considerations for MSE walls and provide design recommendations for cut and
fill slopes.
GENERALIZED SUBSURFACE CONDITIONS
We advanced deep borings on an access road upslope of the highest portions of
the proposed open cuts (for stability analysis). We also completed shallow hand-
auger borings along other portions of the proposed realignment to assess soil
conditions (for pavement design by others). Exploration locations are shown on
Figure 2, and generalized subsurface conditions are shown on Figure 3.
Subsurface conditions presented herein are based on samples collected from
discrete boring locations in the field. Subsurface conditions at other locations
may vary. The nature and extent of any such variations may not become
apparent until additional explorations are performed or until construction
activities have begun. Logs of borings and laboratory test results are included in
Appendices A and B, respectively, at the end of this report.
Geologic Setting
The recent geologic history of the Puget Sound region has been dominated by
several glacial episodes. The most recent, the Vashon stade of the Fraser
glaciation, is responsible for most of the exposed geologic and topographic
conditions in the area. The Puget lobe of the Cordilleran ice sheet deposited a
heterogeneous deposit of proglacial lacustrine soil, advance outwash, lodgment
till, and recessional outwash. These deposits were placed upon either bedrock
or older pre-Vashon sediments and bedrock. Once the melting ice retreated
northward, it uncovered a sculpted landscape of elongate uplands and
intervening valleys. The project site is located within this type of terrain.
The geologic units encountered during drilling generally match those described
in geology references for the site (see References). These references and our
explorations at the site indicate the alignment is underlain by a coarse-grained
sequence of glacial, fluvial, and deltaic deposits. In general, glacially overridden
till, advance outwash, and pre-Vashon sands and gravels are predominant on the
slopes south of SR 106. The till exists on the steeper slopes to the east, while
the advance outwash and pre-Vashon sands and gravels exist on flatter slopes to
the west. North of SR 106, near the Hood Canal, post-glacial alluvial soils
overlying glacially overridden outwash deposits were encountered. Localized
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areas of man-made fill and/or native soil altered by man (i.e., fill) were
encountered near the ground surface in the general location of the sewage
treatment plant.
Subsurface Soil Conditions
Subsurface conditions encountered in our explorations generally indicate
somewhat different soil profiles on the eastern (higher elevations) compared to
the western (lower elevations) portions of the proposed realignment. The
following sections present soil conditions encountered along the eastern portion
of the proposed realignment followed by conditions to the west. We anticipate
soil conditions between/beyond the station ranges indicated below to be similar
to those in the nearest exploration.
Stations 107+00 to 117+00
Subsurface soils encountered in our explorations along the access road generally
consist of the following, in order of increasing depth.
Topsoil. Loose, dark brown, silty, gravelly Sand with abundant roots typically
was encountered to a depth of about 1 to 1.5 feet below the ground surface.
This soil was typically wet in areas where seepage occurred and moist in
topographic high points along the access road. The topsoil typically was present
beneath a few inches of forest duff(i.e., leaves, humus, and decaying organic
material) and contained abundant roots and organic matter. The topsoil is not
suitable for use as structural fill and should be stripped during the site clearing
and grubbing. It may be suitable for reuse in landscape areas, but may contain
too many roots to be of practical use.
Localized Fill. Loose to medium dense, gravelly, silty Sand was encountered to
a depth of 7 feet in boring HC-B5 near the treatment plant. This loose to
medium dense soil appears to represent a zone of mixed Topsoil and
Weathered Glacial Till fill from construction of the bench on which the treatment
plant was constructed. Note that this fill was only encountered in one boring,
and we expect that this represents a localized condition. We expect that
localized overexcavation of loose fill for the road subgrade in this area would be
minor due to its proximity to the proposed realignment.
Wet Weathered Glacial Till. Beneath the Topsoil our explorations encountered
loose, wet, gray, orange, and brown, gravelly, silty to very silty Sand to a depth
of about 2 feet. This material is not suitable as structural fill and should be
discarded unless it can be moisture conditioned and used as landscape fill. It
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has a gradational composition similar to the underlying till except that exposure
to water and weathering has degraded it to a "mud-like" consistency.
Hand-auger borings at Stations 109+00 and 114+50 confirmed generally similar
surficial conditions at these locations. Both HC-HA1 and HC-HA2 encountered
the Topsoil and Wet Weathered Glacial Till with abundant surface seepage
noted.
Glacial Till. Glacial Till consisting of very dense, moist, brown, gravelly, silty to
very silty Sand was encountered beneath the Wet Weathered Glacial Till down
to an elevation of between 30 to 40 feet. Occasional isolated layers/zones of
wet, slightly silty to silty Sand and Gravel were encountered in some of the
borings, which appear to represent isolated zones of perched water. Drill
action, surface evidence, and exposures in nearby road cuts indicate that large
cobbles and boulders are present within this soil unit.
Advance Outwash. In borings advanced to lower elevations very dense, moist
to wet, brown, slightly silty, slightly gravelly to very gravelly Sand to very sandy
Gravel was encountered. The Advance Outwash was typically encountered
below about elevation 35 feet. Geologic maps (see References) of the area
show that this unit is exposed further to the west at lower elevations with flatter
slopes.
Hard Silt. Hard, moist, greenish gray, slightly sandy Silt was encountered in the
bottom of boring HC-133 at about elevation 22 feet. Since available geologic
maps of the area indicate that the Advance Outwash can be up to 200 feet
thick, we anticipate that the hard silt is a relatively thin layer.
No Indication of Old Landslide. Information from an initial site reconnaissance
noted features indicating the potential existence of an older landslide (i.e.,
different types of vegetation, seepage, topographic features, etc.). However,
subsurface conditions encountered in our deep explorations and our review of
aerial photographs of the site (see References) were not conclusive in this regard
and we identified no evidence of a potential old landslide failure plane or zone.
Stations 97+00 to 107+00
Our hand-auger borings in this area generally encountered similar soil types as
described above except that the Glacial Till and Localized Fill units appear to be
absent. Loose soil to a depth of about 2 feet overlying loose to medium dense
soil below 2 feet were encountered in these hand-auger borings. The hand-
augers appear to indicate a transition between Stations 106+00 and 101+00
from Glacial Till below 2 feet to Advance Outwash and/or an older unit of
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gravel/sand (see References). West of Station 101+00 soils generally consisted
of 1 to 1.5 feet of moist Topsoil (same as previous description except moist)
over loose to medium dense, gravelly Sand to gravelly, silty Sand (upper portion
of Advance Outwash or older gravel/sand deposit previously mentioned). Hand-
augers typically encountered refusal on gravels at depths shallower than 4 feet
and may not accurately represent deeper conditions and/or soil density.
Abundant Surficial and Isolated Subsurface Perched Water
Abundant surficial water was encountered perched on top of and within the
Wet Weathered Glacial Till. We observed this surface water seeping out of the
upslope cut of the exploration access road and in areas observed upslope of the
access road. Figure 2 shows three seepage locations upslope of the access road.
These three locations indicate the highest elevation where seepage was noticed
above the access road at the time our explorations were conducted. Noticeable
surficial seepage was also observed near HC-HA1 and HC-HA2.
Based on our observations of borehole samples, less frequent perched
groundwater was encountered in apparent isolated sand lenses within the
Glacial Till. We observed a more significant subsurface perched groundwater
zone in HC-135 downslope of the treatment plant. This area may require
retaining walls or additional measures to control seepage during construction.
Groundwater and seepage conditions represent those at the time of our
observations. Conditions may vary with time due to rainfall, temperature, and
other factors.
GEOTECHNICAL ENGINEERING CONCLUSIONS AND RECOMMENDATIONS
This section of the report presents our geotechnical engineering
recommendations for the design and construction of the proposed roadway.
We have developed our recommendations based on our current understanding
of the project and on our subsurface explorations. If significant variations are
observed at that time, we may need to modify our conclusions and
recommendations accordingly to reflect actual site conditions. If the nature or
location of the construction is different than we have assumed, Hart Crowser
should be notified so we can re-evaluate our recommendations.
General Considerations
Considering the site subsurface conditions and the proposed construction, we
anticipate that the major geotechnical issues for the project are: (1) retention of
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roadway cuts, (2) temporary and permanent drainage for the roadway and cut
slopes, and (3) subgrade support of the roadway fill.
As previously discussed, several different options were considered to support the
cut/fill for the proposed road realignment. As a result, we performed conceptual
design calculations for MSE walls and permanent soil nail walls. However, we
understand that the design team is currently planning to use permanent cut
slopes in cut areas, and that MSE walls could possibly still be used for roadway
fill sections. Therefore, the following sections provide more detailed design
recommendations for permanent cut and fill slopes, and present only a general
description of MSE wall considerations. Other recommendations concerning the
design and construction of the project including site preparation, structural fill,
and pavement sections are presented in the following sections.
Site Preparation
The degree of site preparation necessary is largely dependent on the final road
subgrade elevations along the final alignment and the soil conditions
encountered at those elevations. Based on the proposed road alignment
elevations provided by the project civil engineer (ESA), we recommend that
construction include the following site preparation activities:
1. Clearing and grubbing trees and stumps from the alignment. Stripping
unsuitable surficial organic (i.e., forest duff and topsoil containing roots,
humus, and other decaying plant material),wet, and/or unusable soils from
beneath the road and/or retaining wall (if applicable) areas. Some of the
topsoil and forest duff may be reusable in landscaped areas, but may be
more costly to segregate for reuse. Although the thickness of unusable
material will be highly variable, we recommend for planning purposes that
12 to 18 inches of Topsoil and about 12 to 18 inches of Wet Weathered
Glacial Till be stripped/removed.
2. Collecting, diverting, conveying, and possibly treating (if necessary to
maintain water quality) surficial seepage to avoid soil erosion, maintain slope
stability, maintain suitable soil subgrade, and good working conditions. As
previously indicated, abundant surficial seepage and localized subsurface
perched water are present and will need to be controlled during
construction using conventional means such as, but not limited to, ditches,
sumps, conveyance pipes and/or gutters, and site grading.
3. Overexcavating and replacing localized unsuitable soils (i.e., loose, soft,
disturbed, or wet material) with structural fill as necessary to attain road
subgrade elevations. This localized overexcavation and replacement is in
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addition to the stripping indicated in (1) above and may reach depths of up
to about 3 feet (e.g., near HC-HA5). These areas are typically delineated by
proof rolling the exposed surface with a heavy vibratory roller or loaded
dump truck to determine unsuitable subgrade areas. A representative from
Hart Crowser geotechnical engineering should observe the proof rolling and
probe the exposed subgrade to identify any unsuitable subgrade areas prior
to new fill placement. Unsuitable areas should be overexcavated and/or
compacted to a dense non-yielding condition prior to placement of
structural fill or the pavement section.
Road Cut Slopes and Fill Support
General Considerations
This section presents general design recommendations for:
■ Temporary cut slopes;
■ Permanent cut slopes; and
■ Permanent fill slopes necessary to achieve road grade elevations.
Recommended slopes for the cut and fill sections depend on the following:
■ The presence, quantity, and location of water;
■ The type, density, and strength of the soil;
■ The time that the soil is exposed to weather;
■ The depth of the cut;
■ Surcharge loading (i.e., existing or future structures, construction equipment,
or stockpiled soils, etc.) adjacent to the cut; and
■ Other factors.
We make the following general recommendations for cut and fill slopes.
■ Due to the variety of factors affecting slope stability, and their ability to
change with time and location, it is difficult to precisely calculate the actual
stability of slopes. Thus, it is critical to verify that subsurface conditions at
the time of construction match our design assumptions. Therefore, we
strongly recommend that Hart Crowser be on site during construction of the
slopes and drainage systems.
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■ Open excavations made in proximity to existing structures and utilities (such
as near the Sewer Treatment Plant at about Station 108+00) should be made
with great care and attention. The contractor should be responsible for
verifying all existing utility locations and coordinating their relocation as
necessary prior to beginning construction.
■ The overall cut slopes may experience local softening or sloughing,
particularly where perched water is encountered. We recommend that a
contingency be included (in the project specifications) for geotextile and
quarry spalls/shot rock to aid in drainage treatment or repairs.
■ Implement drainage/seepage control recommendations outlined in the
Drainage/Seepage Control section of this report.
■ Keep construction equipment and activity at least 5 feet (horizontal) from
the top of slopes.
■ The contractor will need to take precautions to minimize both temporary
slope erosion from rainfall and potential dangers from loose, rolling cobbles
or boulders (until erosion control measures are established).
■ We recommend that periodic inspection of the slopes be performed after
completion of construction to ensure proper function of drainage systems.
Temporary Cut Slopes
Because of the variables involved, actual slope values required for stability in
temporary cut areas can only be estimated prior to construction. We
recommend for planning purposes that temporary open cuts be sloped at no
steeper than 1 horizontal:1 vertical (1 HA V) in the very dense, silty to very silty
granular soils (Glacial Till) and 1.5H:1 V in the medium dense, slightly silty
granular soils (Outwash). Groundwater conditions encountered at the time of
construction may dictate that slopes flatter than these will be necessary.
Stability of actual temporary cut slopes should be made the responsibility of the
contractor, since the contractor is in control of the construction operation and is
continuously present at the job site to observe the nature and conditions of the
subsurface material encountered.
Permanent Cut Slopes
We completed preliminary stability analyses to estimate appropriate permanent
slope angles to maintain stable conditions. Our global stability analyses were
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performed at what we feel is the critical section (i.e., Station 112+20 has the
greatest cut slope height). These preliminary analyses considered both static and
seismic (approximated using limit-equilibrium methods) loadings. These analyses
assume that the groundwater elevations are at least 5 feet below the roadway
elevations. Control of water in the slope is critical to controlling surface erosion
and maintaining a stable slope. Refer to Drainage/Seepage Control section
for recommended methods of controlling water in or on the slope.
These analyses resulted in factors of safety of 1.9 for static loading and slightly
greater than 1.0 for seismic loading (peak ground acceleration of 0.33 g
[g = 32.2 ft/sec2]) with 2H:1 V slopes. Based on our analyses, we recommend
that permanent cut slopes be constructed no steeper than 2H:1 V.
We recommend that Hart Crowser be retained to confirm slope stability once
slope configurations are finalized. We would be able to complete this work as
an addition to our original scope of work.
Permanent Fill Slopes/Embankments
Some segments of the realignment will require fill to attain grades. We
recommend the following:
■ Prepare all fill subgrade areas in accordance with the recommendations in
the Site Preparation and Structural Fill sections of this report.
■ Construct all fill slopes no steeper than 21-1:1 V.
■ Where fill is to be placed on slopes steeper than 61-1:1 V, construct benches
(i.e., hillside terraces) at least 5-foot horizontal and less than 5-foot high
excavated into slopes in accordance with Section 2-03.3(14) of the 2002
WSDOT Standard Specifications.
■ Overbuild the outside edge of slopes at least 5 feet beyond final slope lines
and cut back to ensure adequate compaction of structural fill out to the final
slope line.
If sufficient room for fill slopes is not available, MSE walls could be constructed
to attain road grades.
MSE Wall Design Considerations
Based on the aforementioned subsurface conditions, MSE walls are a feasible
method of earth retention for the short (less than 8-foot-high) fill sections of the
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highway realignment. Construction of MSE walls generally consists of
compacting the soil in lifts, placing reinforcing strips between lifts, and placing
wall facing panels on the downslope side to retain the soil. The successful
construction and performance of MSE walls is dependent on several factors such
as:
■ Suitability of supporting subgrade soils;
■ Presence, quantity, and ability to drain water from behind the wall;
■ Type, length, and spacing of reinforcement strips used;
■ Type and installation method of wall facing;
■ Surcharge loads and compaction effort near the wall face during
construction;
■ Consistency of the fill soil; and
■ Attention to construction details especially the connection of facing to
reinforcement.
Hart Crowser is able to provide more detailed MSE wall design information, at a
later date if necessary. However, due to the number of variables involved in
MSE wall design and the uncertainty of whether they will be used on the project,
we have only provided the aforementioned considerations.
Drainage and Seepage Control
Based on our observation of seepage visible at or near the ground surface
during our field work, we anticipate that the majority of surficial seepage would
be encountered between about Station 107+00 and 117+00. Areas of potential
surficial and subsurface seepage indicated in our explorations are noted on
Figures 2 and 3, respectively. Other seepage areas will likely become evident
during the course of construction and should be anticipated by the contractor.
A contingency plan should be added for rock or"blanket drains" to be placed
where wet areas are exposed.
Control Measures. Construction can include several methods to control water
to maintain open cuts, provide retaining wall drainage, and protect subgrade
soils from deterioration. Some of these include, but are not limited to
■ Construction of an interceptor trench upslope of the roadway cut (Stations
107+00 to 1 17+00);
■ Diversion ditches/berms to redirect seeping water;
■ Protection of the cut face with visqueen;
■ Ditch or pipe drain at toe of cut next to roadway; and/or
■ Performing work only during extended dry-weather periods.
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Obviously, construction costs will increase as more combinations of these
measures are required to control water and maintain the cut/fill slopes.
We make the following specific recommendations regarding methods to control
seepage/drainage.
■ Install a permanent interceptor drain and drainage ditch upslope of the
cut/fill slopes and/or work areas to divert surface water and seepage away
from the cut/fill face and/or work areas. Specific recommendations are as
follows:
• Slope drainage ditch at least 2 percent to reduce potential for sediment
accumulation and provide positive discharge.
• Key interceptor drain trench at least 1 foot into the Wet Weathered
Glacial Till.
• Use a minimum 4-inch-diameter perforated pipe surrounded on all sides
by at least 6 inches of drain material (see Drain Material in Structural
Fill section of this report).
• Wrap outside of drainage material with an appropriate geotextile fabric.
• Tightline drains/ditches to a suitable positive discharge point north and
lower in elevation than the proposed realignment subgrade elevation.
■ Install a permanent pipe drain at the toe of the cut slope incorporating the
interceptor drain recommendations above. The pipe iP e for this pipe
e
P
drain should be sized to handle the design flow calculated by the civil
engineer. For planning purposes in the geometric layout of the open-cut
slope, we have assumed that this will be about a 4-inch-diameter pipe (i.e.,
minimum trench width of 16 inches).
• The crown of the perforated pipe should be at least 1 foot below the
bottom of the road grade drainage layer described below.
■ Install a 6-inch-thick layer of drain material placed on the new road subgrade
and beneath the pavement section (see Drain Material in Structural Fill
section of this report).
■ Construct a drainage ditch, or curb and gutter, on the downslope side of the
roadway to collect and convey water from the aforementioned drainage
layer to the closest positive discharge point.
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■ Local areas of additional drainage and subgrade protection measures may be
necessary if significant groundwater seepage is encountered during site
excavations. Provisions should be available to supplement the drainage
system if recommended. Such additions may include additional ditching,
sumping and pumping, use of geotextile with quarry spalls/shot rock to
stabilize small slumps, and/or a greater width of the drainage material.
■ Slope all pavement to drain away from the roadway and provide adequate
runoff disposal.
■ Protect ditches (with quarry spalls, large crushed rock, geotextile erosion
control matting, etc.) conveying surface water to positive discharge points to
avoid erosion of soil. This is especially important for fill slopes and steeper
slopes where flow velocities will be greater.
Additional drainage system components will be required if MSE walls are
incorporated into the design. We have assumed that consideration of
treatment/disposal of turbid water will be designed by ESA. We are able to
assist in this effort if necessary.
Structural Fill
Material and soil that supports loads such as pavement or structures should be
considered structural fill.
General Considerations
Suitability of the on-site soils for reuse as densely compacted structural fill
depends upon the gradation and moisture content of the soil when placed. The
suitability of excavated site soils for compacted structural fill will depend upon
the gradation and moisture content of the soil when it is placed. As the amount
of fines (that portion passing the No. 200 sieve) increases, the soil becomes
increasingly sensitive to small changes in moisture content and adequate
compaction becomes more difficult to achieve. Soil containing more than about
5 percent fines cannot be consistently compacted to a dense non-yielding
condition when the water content is greater than about 2 percent above or
below the optimum water content.
Erosion Potential of Site Soils. Erosion during earthwork activities will need to
be controlled, especially during wet weather conditions. The fines content of
these soils indicates that they are susceptible to erosion, especially when placed
on slopes steeper than about 3HA V. Exposed slopes composed of these soils
may begin to erode in moderate rainfall or windy conditions. Effectiveness of
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filtration (e.g., silt fence or hay bales) may be limited by the high fines content of
the soil. Settling ponds or Baker tanks may be required for effective
sedimentation to maintain quality of water discharge.
We recommend the following:
■ Arrange the construction schedule such that the work can be accomplished
in dry weather to the maximum extent possible.
■ Protect slopes with plastic sheeting until revegetation has been established
to help mitigate erosion of slope faces.
■ Leave sufficient time for revegetation of the slopes.
■ Divert surface water from slope faces until revegetation has been
established. Typically, the Washington State Department of Transportation
requires hydroseeding for slope stabilization,be complete no later than
October 1.
■ Install typical erosion control measures, including but not limited to, silt
fences, hay bales, storm grate filter, etc. prior to construction. Maintain
these measures during and after construction until permanent erosion
control measures are established.
Reuse of On-Site Soils for Structural Fill
Based on our laboratory testing and visual comparison of samples, the majority
of on-site soils have more than about 10 percent, and often more than 25
percent, fines (see Figures B-2 and B-3), and typically appear to be near their
optimum water content for compaction. Thus, use of on-site soils for structural
fill will likely be successful only during extended periods of dry weather.
Therefore, we recommend assuming structural fill will consist of import soils for
MSE walls according to WSDOT specifications. Reusable soil must also be free
of organic and other deleterious material.
The on-site soils may be used in landscaped areas provided that they can be
compacted to a reasonable degree with construction equipment.
Selection of Import Fill
Standard import fills for the project should consist of the following material types
contained in the WSDOT/APWA 2002 Standard Specifications for Road, Bridge,
and Municipal Construction:
Hart Crowser Page 14
7747 January 22,2003
■ Gravel Borrow. Structural fill should conform to Gravel Borrow, Section
9-03.14(1) with the exception that material passing the No. 200 sieve should
not exceed 5 percent based on the minus 3/4-inch fraction.
■ Gravel Backfill for Walls. Fill behind walls should conform to Gravel Backfill
for Walls, Section 9-03.12(2) with the exception that material passing the No.
200 sieve should not exceed 3 percent based on the minus 3/4-inch fraction.
■ Base Course. Base course for roadways should conform to Crushed
Surfacing, Base Course, Section 9-03.9(3).
■ Drain Material. Drain material may consist of Gravel Backfill for Drains,
Section 9-03.12(4), Backfill for Sand Drains Section 9-03.13, or Sand
Drainage Blanket Section 9-03.13(1).
Placement and Compaction of Structural Fill
Before fill compaction control can begin, the compaction characteristics of each
soil type must be determined from representative samples. Representative
samples should be obtained from borrow and/or on-site areas as soon as
grading begins and additional samples should be obtained and tested whenever
characteristics of the borrow materials change. Determination of the
compaction characteristics should include optimum moisture content, maximum
dry density, and moisture content of the soils at the time of placement.
All fill for the project should be placed in accordance with Section 2 of the 2002
WSDOT, APWA Standard Specifications. We provide the following additional
recommendations where we feel clarification or importance of the item is
warranted.
■ The subgrade should be prepared as recommended in the Site
Preparation section.
■ The moisture content of the fill should be controlled within 2 percent of the
optimum moisture. Optimum moisture is the moisture content
corresponding to the maximum dry density as defined by the modified
Proctor test method (ASTM D 1557). If this cannot be achieved, Hart
Crowser should review the intended use of the fill on a case by case basis to
enable recommendations to be made as to feasibility of using the out-of-spec
fill versus necessity of using imported fill for a particular area of construction.
Hart Crowser Page 15
7747 January 22,2003
■ In wet subgrade areas, clean material with a gravel content (material coarser
than a U.S. No. 4 sieve) of at least 30 to 35 percent may be necessary to
provide adequate subgrade support for subsequent fill.
■ Structural fill should not contain cobbles or boulders greater than about
two-thirds of the lift thickness being placed, since these will make it difficult
to compact uniformly, especially when smaller equipment is used.
■ Structural fill placed below any retaining walls/foundations should extend
downward and outward from the footing edge at a slope of 1 H:2V.
Pavement Design Considerations
Actual pavement sections will be designed by others. This section presents
recommendations regarding general pavement subgrade preparation and
pavement design parameters.
Prepare all pavement areas as outlined in the Site Preparation section.
Based on our explorations, we anticipate the support soils for pavement sections
will be loose to medium dense, gravelly, slightly silty Sand from about Station
97+00 to 106+00 and dense, gravelly, silty to very silty Sand from about Station
106+00 to 117+00. All pavement subgrades, however, should be proof rolled
and compacted to a dense condition. Characterization of this material for use as
roadway subgrade would be based on an estimated California Bearing Ratio
(CBR) of 20 percent.
Recommended CBR values for imported fill will depend on soil gradation
characteristics of the soil. If the gradation of the compacted fill is similar to the
on-site soils, a similar CBR value can be used for design purposes. If the
gradation of the import fill varies from the natural, on-site soils, laboratory testing
should be accomplished once the borrow source has been identified to verify
the validity of the CBR value used in design. However, for preliminary pavement
design, we recommend using an estimated CBR of 20 percent for fill material,
assuming the material is compacted to a minimum of 95 percent of the
maximum dry density as determined by the modified Proctor test method (ASTM
D 1557).
Refer to Drainage/Seepage Control section for pavement subgrade
drainage recommendations.
Hart Crowser Page 16
7747 January 22,2003
CONSTRUCTION CONSIDERATIONS
Our observations indicate soil conditions at the site are likely to influence
construction in the following general ways.
■ Take care to control seepage/drainage to maintain good subgrade
conditions and maintain stable cut/fill slopes. Explorations and observations
indicate that abundant seepage likely will occur.
■ Avoid wet weather earthwork. Due to the high percentage of fines (typically
higher than 25 percent) in the native soils, these soils are moisture-sensitive
and will be difficult to compact, especially during wet weather.
■ Include conventional erosion control measures in construction planning.
Soils are more or less silty to very silty, which means they are susceptible to
erosion by wind and water.
■ Remove all organic topsoil prior to construction, or other soils with organic
material which may be encountered below the surface. Organic soils may
be suitable for use as landscape fill, but should not be left in-place below
pavement.
■ The contractor should anticipate the presence of boulders and cobbles,
which may require special handling to remove. We anticipate that
conventional heavy equipment (trackhoe and dozer with a ripper) could
generally be used to accomplish excavation.
RECOMMENDED ADDITIONAL GEOTECHNICAL SERVICES
Before construction begins, we recommend that Hart Crowser be retained to:
■ Meet with the design team periodically as the design plans become more
complete;
■ Review proposed cut slope design prior to the start of final plan preparation,
to estimate factors of safety for stability;
■ Review the final plans to see whether any changes in configuration or other
loadings have occurred that may affect slope stability;
Hart Crowser Page 17
7747 January 22,2003
■ Review the final plans and specifications to see that the geotechnical
engineering recommendations have been properly interpreted and
implemented into the design; and
■ If necessary, we are available to assist ESA in developing TESC plans, water
quality control measures and sampling and analysis, wetland permitting
issues, and salmon habitat creation questions.
During the construction phase of the project, we recommend that Hart Crowser
be retained to observe the following activities:
■ Cut slope excavation to verify that subsurface conditions match those
assumed in our stability analyses;
■ All subgrade preparation and subgrade surfaces prior to fill placement and
pavement section construction;
■ Placement and compaction of structural fill;
■ Installation of shoring (if applicable);
■ Installation of drainage system components; and
■ Other geotechnical considerations that may arise during course of
construction.
The purpose of these observations is to observe compliance with the design
concepts, specifications, or recommendations and to allow design changes or
evaluation of appropriate construction measures in the event that subsurface
conditions differ from those anticipated prior to the start of construction.
Hart Crowser Page 18
7747 January 22,2003
REFERENCES
Geology
Department of Ecology 1997. Costal Zone Atlas.
Molenaar, Dee, and John B. Noble 1970. Geology and Relate Ground-Water
Occurrence, Southeastern Mason County, Washington, State of Washington
Department of Water Resources, Water-Supply Bulletin No. 29.
Soil Survey, Mason County Washington, Series 1951, No. 9, Issued 1960.
Aerial Photographs
Department of Natural Resources, 1981.
Infrared Satellite Photo from UW Library, No title, No source, July 1980.
Microsoft TerraServer, USGS, July 10, 1990, 3km southwest of Tahuya,
Washington.
United States Army Corps of Engineers, 1944.
Washington State Department of Ecology, May 24, 2993, MAS0552.
F:\docs\iobs\7747\Investigation Report.doc
Hart Crowser Page 19
7747 January 22,2003
Figures
Vicinity Map
A s Pooif
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Note: Base map prepared from USGS 7.5 minute quadrangle 0 2000 4000
map of Union,Washington;dated 1985.
Approximate Scale in Feet
Seattle tf>
Union ---- ---- —
I&MCi11 OWS M-
7747 7102
WASHINGTON Figure 1
HC _
r, y
I P �''� -
Ili P,
01
Oj
HC$2
lulydcTle
T- .H6433 6�
\� i est P
East
Seep
At
�.• , "1
�� E �aborrAccess Road.
0 120 240
Scale in Feet
�o Highest Elevation of Observed Surficial Seepage
Surficial Seepage s
L A Cross Section Location and Designation ��,,�
Feet /1/•Vt�ozOwsm
7747 7102
Paure 2
Site and Exploration Plan
10
_ �� 1 % ■ lip � w
C•B9 E oo r /
-
\ SR 106 Realignment _- --
\ POST. //�
OFFICE i `II i Q _ / ,� /// \ ; 7
40
HC-3 idtller,
HC-HA5
East
Seep
Lj
1�Expioiobr�Aa�.�s�s'
o U Y
o Ld
� Q
Note: Base map prepared from an electronic file provided by Engineering Services
Associates entitled,"Alderbrook Soils Block.dwg,"dated May 15,2002(Existing 0 120 240
Features)and updated with electronic files provided by Collins Woerman entitled,
"Hart Crowser Road Alignment.dwg,"dated January 20,2003(Proposed Features). ---- --- Proposed Parking/Buildings Scale In Feet
__o Highest Elevation of Observed Surficial Seepage
Legend:
SR 106 Realignment
� Surficial Seepage A
•HC•131 Existing Features/Buildings Boring Number and Location e� e' �
'�" " Cross Section Location and Designation HA. ' '
50----- Existing Topography Elevation in Feet
■ HC-HA1 Hand-Auger Number and Location 7747 7/02
Figure 2
Appendix A
APPENDIX A
FIELD EXPLORATIONS METHODS AND ANALYSIS
II
II
Hart Crowser
7747 January 22,2003
APPENDIX A
FIELD EXPLORATIONS METHODS AND ANALYSIS
This appendix documents the processes Hart Crowser uses in determining the
nature of the site soils. The discussion includes information on the following
subjects:
■ Explorations and Their Location;
■ The Use of Auger Borings;
■ Standard Penetration Test(SPT) Procedures; and
■ The Use of Hand-Auger Borings.
Explorations and Their Location
Subsurface explorations for this project included five hollow-stem auger borings
and seven hand-auger borings. The exploration logs within this appendix show
our interpretation of the drilling (or augering), sampling, and testing data. They
indicate the depth where the soils change. Note that the change may be
gradual. In the field, we classified the samples taken from the explorations
according to the methods presented on Figure A-1 - Key to Exploration Logs.
This figure also provides a legend explaining the symbols and abbreviations used
in the logs.
Location of Explorations. Figure 2 shows the location of explorations, located
by hand taping or pacing from existing physical features. The ground surface
elevations at these locations were interpreted from elevations shown on Figure
2. The method used determines the accuracy of the location and elevation of
the explorations.
I
I
The locations of the explorations were also determined using a differentially
corrected global positioning system (DGPS) utilizing 1927 North American
i
Datum (NAD 1927), Washington State Plane South zone. However, the base
map used a different coordinate system and exploration locations were plotted
as described above. The following table lists the coordinates collected and is
intended for reference purposes.
I
I
I
I
I
Hart Crowser Page A-1
7747 January 22,2003
Exploration Northing in Easting in Feet
Feet
HC-B1 744,630 1,364,059
HC-B2 744,638 1,364,015
HC-B3 744,637 1,363,903
HC-B4 744,588 1,363,748
HC-B5 744,576 1,363,589
HC-HA1 744,838 1,364,156
HC-HA2 744,598 1,363,697
HC-HA3 744,623 1,363,306
HC-HA4 744,621 1,363,120
HC-HA5 744,582 1,362,926
HC-HA6 744,732 1,362,729
HC-HA7 744,883 1,362,615
East Seepage 744,517 1,364,145
Middle Seepage 744,543 1,364,105
West Seepage 744,498 1,363,893
Horizontal precision is less than 10 feet with one standard deviation from the
mean typically less than 25 feet, but equal to 71 feet for HC-HA6.
Note that the top of seepage areas identified on Figure 2 are at the approximate
locations of the DGPS coordinates. They were placed onto a map with the
DGPS coordinates then transferred, by scaling, to Figure 2.
The Use of Auger Borings
Five hollow-stem auger borings, designated HC-131 through HC-B5, were drilled
from May 3 to 7, 2002, to depths ranging from 30.4 to 61.5 feet below the
ground surface. The borings used a 4-1/4-inch inside diameter hollow-stem
auger and were advanced with both track and truck-mounted drill rigs
subcontracted by Hart Crowser. The drilling was continuously observed by an
engineer from Hart Crowser. Detailed field logs of each boring were prepared.
Using the Standard Penetration Test (SPT), we obtained samples at 2-1/2-to 5-
foot-depth intervals.
The borings logs are presented on Figures A-2 through A-6 at the end of this
appendix.
Hart Crowser Page A-2
7747 January 22,2003
Standard Penetration Test(SPT) Procedures
This test is an approximate measure of soil density and consistency. To be
useful, the results must be used with engineering judgment in conjunction with
other tests. The SPT (as described in ASTM D 1586) was used to obtain
disturbed samples. This test employs a standard 2-inch outside diameter split-
spoon sampler. Using a 140-pound hammer, free-falling 30 inches, the sampler
is driven into the soil for 18 inches. The number of blows required to drive the
sampler the last 12 inches only is the Standard Penetration Resistance. This
resistance, or blow count, measures the relative density of granular soils and the
consistency of cohesive soils. The blow counts are plotted on the boring logs at
their respective sample depths.
Soil samples are recovered from the split-barrel sampler, field classified, and
placed into water tight jars. They are then taken to Hart Crowser's laboratory for
further testing.
In the Event of Hard Driving
Occasionally very dense materials preclude driving the total 18-inch sample.
When this happens, the penetration resistance is entered on logs as follows:
Penetration less than six inches. The log indicates the total number of blows
over the number of inches of penetration.
Penetration greater than six inches. The blow count noted on the log is the
sum of the total number of blows completed after the first six inches of
penetration. This sum is expressed over the number of inches driven that
exceed the first 6 inches. The number of blows needed to drive the first six
inches are not reported. For example, a blow count series of 12 blows for 6
inches, 30 blows for 6 inches, and 50 (the maximum number of blows counted
within a 6-inch increment for SPT) for 3 inches would be recorded as 80/9.
The Use of Hand-Auger Borings
Seven hand-auger borings, designated HC-HA1 through HC-HA7, were
advanced across the site with hand-auger equipment. The hand-auger borings
were located by and advanced by an engineer from Hart Crowser. The engineer
observed the soil obtained from the auger borings and reported the findings on
a field log. Our engineer obtained representative samples of soil types for
testing at Hart Crowser's laboratory. He noted groundwater levels or seepage
during excavation. The density/consistency of the soils (as presented
parenthetically on the hand auger logs to indicate their having been estimated) is
Hart Crowser Page A-3
7747 January 22,2003
based on visual observation only as disturbed soils cannot be measured for in-
place density in the laboratory.
The hand-auger logs for the current study are presented on Figures A-7 through
A-9 at the end of this appendix.
F:\docs\iobs\7747\Investigation Report.doc
Hart Crowser Page A-4
7747 January 22,2003
Key to Exploration Logs
Sample Description
Classification of soils in this report is based on visual field and laboratory observations which include density/consistency,
moisture condition, grain size, and plasticity estimates and should not be construed to imply field nor laboratory testing unless
presented herein. Visual-manual classification methods of ASTM D 2488 were used as an identification guide.
Soil descriptions consist of the following:
Density/consistency, moisture, color, minor constituents, MAJOR CONSTITUENT,additional remarks.
Density/Consistency
Soil density/consistency in borings is related primarily to the Standard Penetration Resistance. Soil density/consistency in test
pits is estimated based on visual observation and is presented parenthetically on the test pit logs.
SAND or GRAVEL Standard SILT or CLAY Standard Approximate
Density Penetration Consistency Penetration Shear Strength
Resistance(N) Resistance(N) in TSF
in Blows/Foot in BlowsfFoot
Very loose 0 4 Very soft 0 - 2 <0.125
Loose 4 - 10 Soft 2 4 0.125 - 0.25
Medium dense 10 30 Medium stiff 4 - 8 0.25 - 0.5
Dense 30 - 50 Stiff 8 - 15 0.5 1.0
Very dense >50 Very stiff 15 - 30 1.0 2.0
Hard >30 >2.0
Moisture Minor Constituents Estimated Percentage
Dry Little perceptible moisture Not identified in description 0- 5
Damp Some perceptible moisture, probably below optimum Slightly (clayey, silty,etc.) 5- 12
Moist Probably near optimum moisture content Clayey, silty,sandy,gravelly 12- 30
Wet Much perceptible moisture, probably above optimum Very (clayey,silty,etc.) 30- 50
Legends
Sampling Test Symbols Test Symbols
Boring Samples Test Pit Samples GS Grain Size Classification
® Split Spoon ® Grab (Jar) CN Consolidation
UU Unconsolidated Undrained Triaxial
Shelby Tube Bag CU Consolidated Undrained Triaxial
® Cuttings Shelby Tube CD Consolidated Drained Triaxial
m Core Run OU Unconfined Compression
DS Direct Shear
* No Sample Recovery
K Permeability
P Tube Pushed, Not Driven PP Pocket Penetrometer
Approximate Compressive Strength in TSF
Groundwater Observation Wells TV Torvane
Approximate Shear Strength in TSF
Im CBR California Bearing Ratio
Concrete Surface Seal MD Moisture Density Relationship
Riser Pipe AL Atterberg Limits
Bentonite Chips 9 Water Content in Percent
ATD— Groundwater Level on Date or I t— Liquid Limit
at Time of Drilling (ATD) Natural
2-Inch-Diameter,0.02-Inch Slot, Plastic Limit
PVC Well Screen PID Photoionization Detector Reading
10/20 Silica Sand CA Chemical Analysis
Native Material
DT In Situ Density Test
Y Groundwater Seepage (Test Pits) mmw
A
MWOWWWR
7747 7102
Figure A-1
Observation Well Log HC-B1
STANDARD PENETRATION LAB
Depth RESISTANCE TESTS
Soil Descriptions in Feet
Approximate Ground Surface Elevation in Feet:78 Sample • Blows per Foot
0 1 2 5 10 20 50 100
(Loose),wet,dark brown,gravelly,silty S-0
SAND with abundant organic material and _
1 roots. To soil 1 0
1 (Loose),wet, gray and brown, gravelly, 8
1 very silty SAND.(Wet Weathered Glacial 5
1_Til-— I S-1 89/10
----------------
Very dense,moist,brown,slightly gravelly ATD
to gravelly,silty to very silty SAND.(Glacial
Till)
4-inch-thick layer of moist to wet,slightly 10 S-2 50/3
silty SAND encountered in sampler.
15 S_3 e 50/4 GS
20
S-4 93110
25 S-5 50/3
Zone of sli htl silty SAND.
30 S-6 MEE 50/5
Bottom of Boring at 30.4 Feet.
Completed 05/03/02.
35
40
45
0
N
50
0
Q
O
U
i
i 55
a
c7
m
O
r
60
U
O
z
o
65
1.Refer to Figure A-1 for explanation of descriptions and symbols. 1 2 5 10 20 50 100
2.Soil descriptions and stratum lines are interpretive and actual changes • Water Content in Percent
may be gradual.
3.Groundwater level,if indicated,is at time of drilling(ATD)or for date t/
specified. Level may vary with time. as
4.Top of casing,inside stick up monument,approximately 4 feet above
ground surface. HA.du"0YMM
5.All borings advanced through access road base,about 1 foot thick,
consisting of 2-to 4-inch-diameter angular quarry spalls on Wet
Weathered Glacial Till. Access road cut typically is 1 to 2 feet below 7747 05102
adjacent upslope ground surface. Figure Q-2
6.ATD water level may reflect water seeping down from surface. Significant 9
seepage noted in upper 2 feet of access road cut upslope.
Boring Log HC-B2
STANDARD PENETRATION LAB
Depth RESISTANCE TESTS
Soil Descriptions in Feet
Approximate Ground Surface Elevation in Feet:79 Sample • Blows per Foot
0 1 2 5 10 20 50 100
(Loose),wet,dark brown,gravelly,silty
SAND with abundant organic material and _
1 roots. To soil f
1 (Loose),wet,gray and brown, gravelly, f
1 very silty SAND. (Wet Weathered Glacial 5
1_ Till-----------------f S-1
Very dense, moist,brown,gravelly to very
gravelly, silty to very silty SAND. (GlacialSZ
Till) 10 ATD
Zones of slightly silty SAND. S-2 80/11
15 •S-3
50/3
20 S-4
50/5
Zone of silty,very sandy GRAVEL with 25 S_5 A GS
reddish brown Clay infilling within the 8 99/11
Glacial Till.
30 S-6
i50/5
Sand content increases. 35 S-7 50/5
Very dense, moist to wet,brown, slightly
silty,very sandy GRAVEL. (Outwash?) 40
Bottom of Boring at 40.5 Feet. S-8 50/2 GS
Completed 05/03/02.
45
N
O
(7
N
n
� 50
0
0
0
U
U
i
= 55
a
C7
M
m
n
it o
n
60
O
J
C
Z
2
O
m 65
1.Refer to Figure A-1 for explanation of descriptions and symbols. 1 2 5 10 20 50 100
2.Soil descriptions and stratum lines are interpretive and actual changes • Water Content in Percent
may be gradual.
3.Groundwater level, if indicated,is at time of drilling(ATD)or for date AM
specified. Level may vary with time. as
4.All borings advanced through access road base,about 1 foot thick,
consisting of 2-to 4-inch-diameter angular quarry spalls on Wet LJ�e�Y'j�OrA
Weathered Glacial Till. Access road cut typically is 1 to 2 feet below HA. K �.�1 ER
adjacent upslope ground surface.
5.4-foot water level measured inside auger after drilling and water level 7747 05102
stabilized.
6.ATD water level may reflect water seeping down from surface. Significant Figure A-3
seepage noted in upper 2 feet of access road cut upslope.
Boring Log HC-B3
STANDARD PENETRATION LAB
Depth RESISTANCE TESTS
Soil Descriptions in Feet
Approximate Ground Surface Elevation in Feet:80 Sample . Blows per Foot
0 1 2 5 10 20 50 100
(Loose),wet,dark brown,gravelly,silty
SAND with abundant organic material and S-0 •
t roots. To soil f
(Medium stiff),wet, reddish brown,gravelly, S-1
` very sandy SILT. (Wet Weathered Glacial / 5
-Ti ll -----------------J S-2
Very dense,moist, brown(with gray in
sample S 1),gravelly,silty to very silty
SAND. Glacial Till
Dense,wet,brown,silty,gravelly SAND. 10 ATD S-3 • GS
(Interbed within Glacial Till)
Very dense,moist, brown,gravelly, silty to
very silty SAND. (Glacial Till) 15
S-4 97/10
Layer of moist to wet,slightly silty SAND 20 S-5 e
with trace Gravel in top 4 inches of 64/11
sampler.
Very dense,moist to wet,silty,very 25 (4.)S-6 50/4 GS
gravelly SAND. (Interbed within Glacial Till)
Very dense,moist, brown,silty to very silty,
gravelly to very gravelly SAND. (Glacial
Till) 30 (4.)S-7 50/6
Zone with some reddish brown Clay infilling 35 S-6 50/2
and wet zones where more gravelly.
40
80/10
Very dense, moist with occasional we 45 S-10 •
zones, reddish brown,slightly gravelly, 91/10
g slightly silty to silty SAND. (Transition into
Advance Outwash?)
50 S-11
0 50/6
c�
O
U
i 55
a
S-12 •
c7
m Hard, moist,greenish gray,slightly sandy
SILT with horizontal laminations and 60
o layers. S-13 •f r
L
0 Bottom of Boring at 61.5 Feet.
Q Completed 05/06/02.
m
165 1 2 5 10 20 50 100
• Water Content in Percent
1.Refer to Figure A-1 for explanation of descriptions and symbols. RV
2.Soil descriptions and stratum lines are interpretive and actual changes MR
may be gradual.
3.Groundwater level,if indicated,is at time of drilling(ATD)or for date LJ�n�Y"/�Or/�
specified. Level may vary with time. HAR �..�1 ER
4.Blow count may not be representative of density due to gravel.
5.All borings advanced through access road base,about 1 foot thick, 7747 05102
consisting of 2-to 4-inch-diameter angular quarry spalls on Wet
Weathered Glacial Till. Access road cut typically is 1 to 2 feet below Figure A-4
adjacent upslope ground surface.
Boring Log HC-B4
STANDARD PENETRATION LAB
Soil Descriptions Depth RESISTANCE TESTS
in Feet Sample • Blows per Foot
Approximate Ground Surface Elevation in Feet:70
1 2 5 10 20 50 100
(Loose),wet,dark brown,gravelly,silty
0
SAND with abundant organic material and
roots. (Topsoil)
Medium dense,moist to wet,brown and
reddish brown, gravelly,silty to very silty 5
SAND. (Wet Weathered Glacial Till) S-1
------------------------
Very dense,moist,brown,gravelly,silty to
very silty SAND.(Glacial Till) tio
15 S-3
50/5
Becomes gravelly to very gravelly,silty to 20 S-4
very silty SAND.
25 S-5
50/3
Zone of reddish brown Cla infillin 30 (4)S- s 50/2
Bottom of Boring at 30.8 Feet. (4.)S
Completed 05/03/02.
35
Auger refusal at 30.5 feet on large
cobble/boulder. Second SPT sample S-7
attempted to get sample of rock
unsuccessfully. 40
45
0
N
50
0
Q
0
U
= 55
a
c�
m
e
^ 60
c�
0
J
0
Z
121
m 165
1 2 5 10 20 50 100
• Water Content in Percent
1.Refer to Figure A-1 for explanation of descriptions and symbols. mmw
2.Soil descriptions and stratum lines are interpretive and actual changes
may be gradual.
3.Groundwater level,if indicated,is at time of drilling(ATD)or for date /./A A7'r�IO�AMrf1
specified. Level may vary with time. � A. R w� ��.7E
4. Blow count may not be representative of density due to gravel.
5.All borings advanced through access road base,about 1 foot thick, 7747 05102
consisting of 2-to 4-inch-diameter angular quarry spalls on Wet Figure A-5
Weathered Till. Access road cut typically is 1 to 2 feet below adjacent 9
upslope ground surface.
Observation Well Log HC-B5
STANDARD PENETRATION LAB
Depth RESISTANCE TESTS
Soil Descriptions in Feet
Approximate Ground Surface Elevation in Feet:60 Sample . Blows per Foot
p 1 2 5 10 20 50 100
(Loose),wet,dark brown,gravelly,silty
SAND with abundant organic material and S-1
roots. To soil
Loose to medium dense, moist,brown, S-2 •
gravelly,silty SAND with occasional roots. 5
(Topsoil and Weathered Glacial Till Fill S-3
from treatment plant bench
Dense, moist,gray with brown and orange S-4
mottling,slightly silty to silty,gravelly 10
SAND. (Weathered Glacial Till)
Medium dense,wet,brown and gray,
slightly silty,very sandy GRAVEL. o
(Interbed within Glacial Till) m S-5A GS
15 «�
Very dense,moist with occasional wet a
zones, brown with orange mottling, silty,
gravelly SAND.(Glacial Till) S-6
Some reddish brown Clay infilling. 20
Occasional wet,slightly silty zones. S-7 50/5
25
S-B 50/1
30
S-9 50/4
--------------------
Very dense,moist, brown,slightly gravelly,,
slightly silty SAND. (Transition to 35
Outwash?)
S-10 50/3
Bottom of Boring at 38.8 Feet. 40
Completed 05/07/02.
45
0
i7
N
n
� 50
0
a0.
0
U
= 55
a
0
m
a
60
0
J
Z
Z
Q
0
in 65
1 2 5 10 20 50 100
• Water Content in Percent
1.Refer to Figure A-1 for explanation of descriptions and symbols. f�
2.Soil descriptions and stratum lines are interpretive and actual changes
may be gradual.
3.Groundwater level,if indicated,is at time of drilling(ATD)or for date L/�nrt/�sO �/�
specified. Level may vary with time. rlAK �.I[ D-
4.Blow count may not be representative of density due to gravel.
5.All borings advanced through access road base,about 1 foot thick, 7747 05102
consisting of 2-to 4-inch-diameter angular quarry spalls on Wet
Weathered Glacial Till. Access road cut typically is 1 to 2 feet below Figure A-6
adjacent upslope ground surface.
Hand-Auger Boring Log HC-HA 1
Sample Water Depth SOIL DESCRIPTIONS
Content in Feet Approximate Ground Surface Elevation in Feet 45
Forest Duff over(very loose),wet(saturated),dark brown,silt( ry ) ( ) y,gravelly
S-1 SAND with abundant organic material and small roots. (Topsoil)
1 AT (Very loose to loose),wet,gray with reddish brown mottlin silty,
( ry ) g y g, gravelly
SAND. (Top of Wet Weathered Glacial Till?)
2
S-2 21
3 Bottom of Exploration at 2.8 Feet.
Completed 05/09/02.
4 Advanced in area with noticeable surface seepage. Refusal on large
gravel at 2.8 feet.
5-
Hand-Auger Boring Log HC-HA2
Sample Water Depth SOIL DESCRIPTIONS
Content in Feet Approximate Ground Surface Elevation in Feet:49
Forest Duff over wet,dark brown,silty,
(loose), gravelly SAND with
S-1 abundant small roots. (Topsoil)
1 AST (Loose),wet,brown with some gray and orange mottling, silty,S-2 13 ( ) 9 Y 9 9, gravelly NP
to 3-inch diameter SAND. To of Wet Weathered Glacial Till?
Bottom of Exploration at 1.5 Feet.
2 Completed 05/09/02.
3 Refusal on gravel at 1.5 feet. Advanced in area of old drainage ditch,but
no surface seepage noted during augering. Side wall sloughing below
water surface.
a
5
Hand-Auger Boring Log HC-HA3
N Sample Water Depth SOIL DESCRIPTIONS
Content inOFeet Approximate Ground Surface Elevation in Feet 53
Forest Duff over(loose),moist,dark brown,slightly silty,gravelly SAND
0 S-1 with abundant small roots. (Topsoil)
0 1 (Loose to medium dense), moist, reddish brown,slightly silty to silty
gravelly(up to 2-inch diameter)SAND.
= S-2 14
a 2 ----
0 (Medium dense),moist,brown,slightly silty,gravelly(up to 4-inch
a diameter)SAND. (Outwash?)
S-3 10 3
w
C7
a
IL
cr
Ui
C a Bottom of Exploration at 4.0 Feet.
o Completed 05/06/02.
J
5
No groundwater observed ATD. Refusal on gravel at 4 feet and very
difficult augering last foot.
fW
u
H/. K"OWSCJ?
1.Refer to Figure A-1 for explanation of descriptions and symbols.
2.Soil descriptions and stratum lines are interpretive and actual changes 7747 05102
may be gradual.
3.Groundwater conditions,if indicated,are at time of excavation. Conditions Figure A-7
may vary with time.
Hand-Auger Boring Log HC-HA4
Sample Water Depth SOIL DESCRIPTIONS
Content in Feet Approximate Ground Surface Elevation in Feet:52
Forest Duff over(loose),moist,dark brown, silty, ravel)
S-1 2a ( ) ty gravelly(up to 1 inch
diameter)SAND with abundant small roots. (Topsoil)
-----------------------------------
1 (Loose),moist,reddish brown,silty,slightly gravelly SAND.(Bottom of
Topsoil?)
2
S-2 20
S-3 32 (Soft to medium stiff),moist to wet,gray with orange mottling,slightly
3 gravelly,sandy SILT. (Top of Wet Weathered Glacial Till?)
4 Bottom of Exploration at 4.0 Feet.
Completed 05/06/02.
5
Refusal on gravel at 4 feet. No groundwater observed ATD.
Hand-Auger Boring Log HC-HA5
Sample Water Depth SOIL DESCRIPTIONS
Content in Feet Approximate Ground Surface Elevation in Feet:58
Forest Duff over(loose),moist,dark brown,silty,gravelly SAND with small
S 1 roots. (Topsoil)
1
(Loose to medium dense),moist,tan to brown, slightly silty,gravelly SAND
that becomes siltier with depth. (Transition between Weathered Glacial Till
2 and Outwash as move West?)
S-2 12
3
Bottom of Exploration at 3.3 Feet.
Completed 05/08/02.
4
Refusal on gravel at 3.3 feet. No groundwater observed ATD.
5-
Hand-Auger Boring Log HC-HA6
o Sample Water Depth SOIL DESCRIPTIONS
Content in Feet Approximate Ground Surface Elevation in Feet:45
0 Forest Duff over(loose),moist, black, silt
o g-1 ( ) y,gravelly(up to 3-inch diameter)
� SAND with abundant small roots. To soil
o S-2 g t (Loose),moist,reddish brown,silty,gravelly(up to 3-inch diameter) SAND.
Bottom of Topsoil?)
(Loose to medium dense),moist,brown,gravelly(up to 3-to 4-inch
S-3 14 diameter)SAND with trace Silt. (Outwash?)
0 2 Bottom of Exploration at 2.0 Feet.
cL
Completed 05/08/02.
3
Lu
Refusal on gravel at 2 feet. No groundwater observed ATD.
a
a
a a
w
c�
O
J
5
MW
(`R
/Z oWSER
1.Refer to Figure A-1 for explanation of descriptions and symbols.
2.Soil descriptions and stratum lines are interpretive and actual changes 7747 05102
may be gradual.
3.Groundwater conditions,if indicated,are at time of excavation. Conditions Figure A-8
may vary with time.
Hand-Auger Boring Log HC-HA7
Sample Water Depth SOIL DESCRIPTIONS
Content in Feet Approximate Ground Surface Elevation in Feet 36
S-1 Forrest Duff over(loose),moist,black,silty to very silty,gravelly(up to
__ 3 inch diametej SAND with abundant small roots.�To�soih______
ND.(Loose), moist,reddish brown,silty,gravelly SA (Bottom of Topsoil?)
1
S-2 9
2 (Loose to medium dense),moist,brown,gravelly SAND with trace Silt.
(Outwash?)
S-3 6 3
4 Bottom of Exploration at 4.0 Feet.
Completed 05/08/02.
5
No groundwater observed ATD.
N
O
N
t`
r
0
a cc
V
U
V
a
a
F
v
n
r`
w
Q
a
a
C0
U
MrV
N
AW
1. Refer to Figure A-1 for explanation of descriptions and symbols.
2.Soil descriptions and stratum lines are interpretive and actual changes 7747 05102
may be gradual.
3.Groundwater conditions,if indicated,are at time of excavation. Conditions Figure A-9
may vary with time.
Appendix B
APPENDIX B
LABORATORY TES
TING PROGRAM
Hart Crowser
7747 January 22,2003
APPENDIX B
LABORATORY TESTING PROGRAM
A laboratory testing program was performed for this study to evaluate the basic
index and geotechnical engineering properties of the site soils. The tests
performed and the procedures followed are outlined below.
Soil Classification
Field Observation and Laboratory Analysis. Soil samples from the explorations
were visually classified in the field and then taken to our laboratory where the
classifications were verified in a relative) controlled laboratory environment.
Y rY
Field and laboratoryobservations
o o s include density/consistency, moisture
condition, and grain size and plasticity estimates.
The classifications of selected samples were checked b laboratory p y y tests such as
Atterberg limits determinations and grain size analyses. Classifications were
made in general accordance with the Unified Soil Classification (USC) System,
ASTM D 2487, as presented on Figure B-1.
Water Content Determinations
Water contents were determined for most samples recovered in the explorations
in general accordance with ASTM D 2216, as soon as possible following their
arrival in our laboratory. Water contents were not determined for very small
samples nor samples where large gravel contents would result in values
considered unrepresentative. The results of these tests are plotted at the
respective sample depth on the exploration logs. In addition, water contents are
routinely determined for samples subjected to other testing. These are also
presented on the exploration logs.
Grain Size Analysis (GS)
Grain size distribution was analyzed on representative samples in general
accordance with ASTM D 422. Wet sieve analysis was used to determine the
size distribution greater than the U.S. No. 200 mesh sieve. The size distribution
for particles smaller than the No. 200 mesh sieve was determined by the
hydrometer method for a selected number of samples. The results of the tests
are presented as curves on Figures B-2 and B-3 plotting percent finer by weight
versus grain size.
Hart Crowser Page B-1
7747 January 22,2003
Atterberg Limits (AL)
We determined Atterberg limits for selected fine-grained soil samples. The liquid
limit and plastic limit were determined in general accordance with ASTM D
4318. The results of the Atterberg limits analyses and the plasticity
characteristics are summarized in the Liquid and Plastic Limits Test Report,
Figure B-4. This relates the plasticity index (liquid limit minus the plastic limit) to
the liquid limit. The results of the Atterberg limits tests are shown graphically on
the boring logs as well as where applicable on figures presenting various other
test results.
F:\docs\jobs\7747\Investigation Report.doc
Hart Crowser Page B-2
7747 January 22,2003
Unified Soil Classification (USC) System
Soil Grain Size
Size of Opening In Inches Number of Mesh per Inch
(US Standard) Grain Size in Millimetres
N N 'Q a0 N � Oo O
(0 V N�� M in r) O N Y too N O O O O O O O O O p O
O O O O O O O O O co W O Cl) N Cq (P V 17 N '- o) O en N Go (p M N
O O O co10 V M N O O O O O 0 0 O O O O
Grain Size in Millimetres
COBBLES GRAVEL SAND SILT and CLAY i
Coarse-Grained Soils Fine-Grained Soils j
Coarse-Grained Soils
_
GW GP J� GM GC SW SP SM I SC
Clean GRAVEL<5%fines GRAVEL with>12%fines Clean SAND<5%fines SAND with>12/o fines
GRAVEL>50%coarse fraction larger than No.4 SAND>50%coarse fraction smaller than No.4
Coarse-Grained Soils>50%larger than No.200 sieve
r D60`,>4 for G W (D30)2
G Wand S W D >6 for S W & 1< <3 G P and S P Clean GRAVEL or SAND not meeting
10, D10 X D60j requirements for G W and S W
G M and S M Atterberg limits below A line with PI<4 G C and S C Atterberg limits above A Line with PI>7
*Coarse-grained soils with percentage of fines between 5 and 12 are considered borderline cases requiring use of dual symbols.
D10,D30,and D60 are the particles diameter of which 10,30,and 60 percent,respectively,of the soil weight are finer.
Fine-Grained Soils
ML CL OL MH CH OH Pt
SILT CLAY Organic SILT CLAY Organic Highly
Organic
j Soils with Liquid Limit<50% Soils with Liquid Limit>50% Soils
Fine-Grained Soils>50%smaller than No.200 sieve
60 1 60
50 C H 50
40 40
C L
30 30
5
a- 20 MHorOH 20
10 — CL - ML ML 10
or0L
0 0 10 20 30 40 50 60 70 80 90 0100
Liquid Limit
Arm
�As
r i.Yz/CROWSM-
HC StandardslStandard Repoli FguresrGrain Size(&1).CDR 7747 6102
Figure 8-1
PARTICLE SIZE DISTRIBUTION TEST REPORT
100
90
80
70
w 60
W
Z
LL
Z 50
W
U
Of
W
40
a
i
30
20
10
0
200 100 10 1 0.1 0.01 0.001
GRAIN SIZE- mm
%+ 3" GRAVEL %SAND % FINES
CRS. FINE CRS. MEDIUM FINE SILT CLAY
i
0 0.0 0.0 11.2 7.7 12.3 19.8 49.0
0 0.0 7.1 46.0 15.5 10.2 4.8 16.4
0 0.0 19.3 38.0 8.2 1 15.2 1 11.3 8.0
LL PI D85 D60 1350 D30 D15 1310 Cc Cu
0 3.00 0.197 0.0821
❑ 15.5 7.34 5.31 1.76
o 21.1 11.7 7.63 0.995 0.288 0.125 0.68 93.47
MATERIAL DESCRIPTION USCS NAT. MOIST.
o Slightly gravelly,very silty SAND SM 12%
o Silty,very sandy GRAVEL GM 10%
o Sli tly siltv,very sandy GRAVEL GP-GM 8%
Remarks: Project: Alderbrook SR 106 Relocation
o Small sample size
❑ Small sample size Client:
o Small sample size o Source:HC-B1 Sample No.: S-3B
❑ Source: HC-B2 Sample No.: S-5B
o Source: HC-B2 Sample No.: S-8
A
uA. WCRAL � ��++�� 7747 5/21/2002
J40WSM Figure No. B-2
PARTICLE SIZE DISTRIBUTION TEST REPORT
g
100
80
70
w 60
Z
�L Z 50
W
U
lr
a 40
90
20
10
0
200 100 10 1 0.1 0.01 0.001
GRAIN SIZE- mm
% +3..
°h GRAVEL % SAND % FINES
CRS. FINE CRS. MEDIUM FINE SILT CLAY
0 0.0 19.3 7.8 3.6 8.5 35.0 25.8
13 0.0 19.0 21.9 9.7 13.0 23.0 13.4
0 0.0 11.7 1 37.2 12.6 15.5 13.7 9.3
LL PI D85 D60 D50 D30 D15 D10 Cc Cu
0 25.2 0.397 0.226 0.0932
11 20.6 4.99 2.15 0.307 0.100
0 16.4 7.79 4.41 0.859 0.191 0.0861 1.10 90A 1
MATERIAL DESCRIPTION USCS NAT. MOIST.
o Silty,gravelly,medium to fine SAND SM 13%
❑ Silty,very gravelly SAND SM 9%
o Slightly silty,very sandy GRAVEL GW-GM 9%
Remarks: Project: Alderbrook SR 106 Relocation
o Small sample size
❑ Small sample size Client:
o Small sample size o Source: HC-B3 Sample No.: S-3
❑ Source:HC-B3 Sample No.: S-6
o Source: HC-B5 Sample No.: S-5
A
V 7747 5/21/2002
HN�TCROWSM Figure No. B-3
LIQUID AND PLASTIC LIMITS TEST REPORT
60 Dashed line indicates the approximate
upper limit boundary for natural soils
50 / O
/
40 '
x /
w /
U 30 /
H /
U
20
G\o`
/
10
7 --- ,
4 —
� 5 ML or OL MH or OH
10 30 50 70 90 110
LIQUID LIMIT
Location + Description LL PL PI -200 Uscs
• Source:HC-B3 Sample No.: S-13
SILT 26 25 1 ML
Remarks: Project: Alderbrook SR 106 Relocation
•
Client:
Location:
A
V 7747 5/21/2002
HAWCR0WSER Figure No. B-4