Geotechnical Investigation GEOTECHNICAL INVESTIGATION
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CITY OF TIGARD LIBRARY
TIGARD, OREGON
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GEOCON Beaverton,OR 97008-6443
NORTHWEST Tel. (503)626-9889
GEOTECHNICAL Fax (503)626-8611
CONSULTANTS Mobile(503)516-5931
geoconnw@geoconnw.com
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MAY 2002
GEOCON
N O R T H W E S T, I N C.
GEOTECHNICAL CONSULTANTS _
Project No. P1150-05-01
May 10, 2000
City of Tigard
13125 SW Hall Boulevard
Tigard, Oregon 97223
Attention: Ms. Vannite Nguyen
Subject: CITY OF TIGARD LIBRARY
TIGARD, OREGON
GEOTECHNICAL INVESTIGATION
Dear Ms. Nguyen:
In accordance with our proposal number P02-05-45, dated April 18, 2002, and your
authorization, we have performed a geotechnical investigation for the proposed City of
Tigard Library in Tigard, Oregon. The accompanying report presents the findings of the
geotechnical investigation and conclusions and recommendations regarding the
geotechnical aspects of the proposed development. Based on the results of this
investigation, it is our opinion that the library site can be developed as proposed, provided
the recommendations of this report are followed. The primary geotechnical issue
associated with the project is the high moisture content of near surface soils.
If you have questions regarding this report, or if we may be of further service, please contact
the undersigned at your convenience.
Sincerely,
GEOCON NORTHWEST, INCORPORATED
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Heather Devine, P.E. Y Wesley Spang, Ph.D., P. .
Geotechnical Engineer President
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TABLE OF CONTENTS
1. PURPOSE AND SCOPE 1
2. SITE AND PROJECT DESCRIPTION 1
3. REGIONAL GEOLOGY AND SEISMIC HAZARDS 2
3.1. REGIONAL GEOLOGY 2
3.2. GEOLOGIC HAZARDS 2
4. SUBSURFACE EXPLORATION AND CONDITIONS 4
4.1. SITE EXPLORATION 4
4.2. SUBSURFACE CONDITIONS 6
5. LABORATORY TESTING 7
6. CONCLUSIONS AND RECOMMENDATIONS 7
_ 6.1. GENERAL 7
6.2. SITE PREPARATION 8
6.3. PROOF ROLLING 10
6.4. FILLS 10
6.5. SURFACE AND SUBSURFACE DRAINAGE 11
6.6. FOUNDATIONS 11
6.7. CONCRETE SLABS-ON-GRADE 12
6.8. RETAINING WALLS AND LATERAL LOADS 13
6.9. UBC DESIGN CRITERIA 15
6.10. EXCAVATION CHARACTERISTICS 16
6.11. PAVEMENT DESIGN 16
7. FUTURE GEOTECHNICAL SERVICES 18
8. LIMITATIONS 18
REFERENCES
MAPS AND ILLUSTRATIONS
APPENDIX A
FIELD INVESTIGATION
BORINGS
APPENDIX B
FIELD INVESTIGATION
IN SITU TESTING
APPENDIX C
LABORATORY TESTING
GEOTECHNICAL INVESTIGATION
1. PURPOSE AND SCOPE
This report presents the results of the geotechnical investigation for the proposed City of
Tigard Library in Tigard, Oregon. The site is located east of SW Hall Boulevard at the
intersection of SW O'Mara Street, as shown in Figure 1, Site Vicinity Map. The purpose of
the geotechnical investigation was to evaluate subsurface soil and geologic conditions at the
site and, based on the conditions encountered, provide conclusions and recommendations
pertaining to the geotechnical aspects of the proposed library construction.
The scope of the investigation consisted of a site reconnaissance, review of published
geological literature, and a field investigation. The field investigation consisted of two
exploratory borings to depths of 51.5 feet below the ground surface (bgs), four dilatometer
(DMT) soundings to depths of approximately 30 to 50 feet bgs, and a seismic cone
penetration (CPT) sounding, advanced to approximately 50 feet below the ground surface.
_ A detailed discussion of the field investigation is presented in Section 4 of this report.
Exploratory logs are presented in Appendices A and B.
Laboratory tests were performed on selected soil samples obtained during the investigation
to evaluate pertinent physical properties. Appendix C presents a summary of the laboratory
test results. The results of laboratory moisture content tests are presented on the boring
logs, located in Appendix A.
The recommendations presented herein are based on an analysis of the data obtained
during the investigation, laboratory test results and our experience with similar soil and
geologic conditions within the project vicinity. This report has been prepared for the
exclusive use of the City of Tigard and their agents, for specific application to this project, in
accordance with generally accepted geotechnical engineering practice. This report may not
contain sufficient information for purposes of other parties or other uses.
2. SITE AND PROJECT DESCRIPTION
The proposed library site is approximately 14.7 acres and is located within T2S, R1W,
Sections 1 and 2, in Washington County, Oregon, in the City of Tigard, on the east side of
the intersection of SW Hall Boulevard and SW O'Mara Street. The approximate location is
shown in Figure 1, Site Vicinity Map. The site is currently used as a pasture. Fanno Creek
flows adjacent to the east and north portions of the project site. Two structures are located
at the northwest portion of the site and three structures occupy the southwest portion.
P1150-05-01 - 1 - May 10, 2002
The proposed project consists of an on-grade two-story, 47,000 square foot library with
associated access roads, parking, pedestrian walkways, and landscaping. No basements
or underground structures are planned. Based on the observed topography of the site, it is
expected that site grading will consist of moderate cuts and fills.
3. REGIONAL GEOLOGY AND SEISMIC HAZARDS
3.1. Regional Geology
Based on the State of Oregon Department of Geology and Mineral Industries' (DOGAMI)
Open File Report 0-90-2, the site is mapped within an area of Pleistocene age fine-grained
facies to a depth of approximately 60 feet bgs. These Pleistocene age deposits are
characterized by brown to buff, unconsolidated beds and lenses of coarse-grained sand to
silt. The fine-grained facies are slack water fluvial and/or lacustrine deposits resulting from
repeated temporary inundation of the Willamette Valley by Late-Pleistocene glacial outburst
floods. These glacial floods originated in the Missoula Valley of Montana, passed through
eastern Washington, and followed the Columbia River downstream. When these large
floods entered the Portland Basin they flowed up the Willamette River and its tributaries,
flooding most of the Willamette and Tualatin Valleys up to an approximate elevation of 350
feet MSL. The last of these glacial floods, also thought to be one of the largest, occurred
about 12,400 years ago, establishing the minimum age of the silt deposit. Below the
surface deposit is a Pliocene age sandstone and conglomerate of inundated beds and
_ lenses of well sorted sand and gravel, typically referred to as the Troutdale Formation. The
Troutdale Formation occurs primarily in the valleys of the Willamette, Clackamas and Sandy
Rivers, as well as along many of their tributaries. Older bedrock units are mapped at a
depth of approximately 450 feet below the ground surface.
3.2. Geologic Hazards
3.2.1 Landslide Hazard
Due to the relatively flat topography of the building site, landslide hazard is
considered negligible.
3.2.2 Crustal Faults
Based on the literature review, there are no identified faults mapped within the
boundaries of the site or within adjacent properties. Evidence was not encountered
P1150-05-01 -2- May 10, 2002
during the field investigation to suggest the presence of faults within the property.
The potential for fault displacement and associated ground subsidence at the site
is considered remote.
- 3.2.3 Soil Liquefaction Potential
Liquefaction can cause aerial and differential settlement, lateral spreading, and
sudden loss of soil shear strength. Soils prone to liquefaction are typically loose,
saturated sands and, to a lesser degree, silt. Liquefaction susceptible soils
typically consist of geologically young alluvial deposits and man-made fills. Recent
studies (Andrews, 2000) indicate that soils with 10% or more grainsize less than
_ 0.002mm and a liquid limit greater than or equal to 32 are not susceptible to
liquefaction. Laboratory test results of samples collected below the groundwater
table show the soils at this site to be non- plastic with approximately 10% to 11%
grainsize less than 0.002. Since both criteria are not satisfied, further analysis of
liquefaction susceptibility is required. Liquefaction analysis consists of computing
- the cyclic shear stresses induced in the soil by seismic shaking and calculating the
cyclic shear strength (resistance) of the soil that is available to resist the seismic
loading. Comparison of the soil shear strength to the induced seismic shear stress
determines the susceptibility of the underlying soil to liquefaction or shear strength
loss. The results of our analyses for the library site indicate that isolated soil
- lenses near a depth of 20 feet below the ground surface, comprising a total
thickness of approximately one foot, may be marginally susceptible to liquefaction
under a design Magnitude 6 earthquake. However, should liquefaction of these soil
lenses occur, it is estimated that dynamic settlement would be less than one inch.
The remaining soil profile has negligible potential for liquefaction.
3.2.4 Lateral Spread
Lateral spreading is a liquefaction related seismic hazard that may adversely
impact some sites. Areas subject to lateral spreading are underlain by liquefiable
- sediments and are sloping sites or flat sites adjacent to an open face. Due to the
proximity of the stream bank associated with Fanno Creek to the project site, an
analysis was conducted based on liquefaction of the lenses discussed above. This
-
analysis is dependent upon the average grain size and the percentage of fine-
grained material of the soils susceptible to liquefaction, as well as geometric
- relationships of slope heights and distances. Our analysis indicates that no
significant lateral spread deformation will occur within the library building pad under
a design Magnitude 6 earthquake.
P1150-05-01 -3- May 10, 2002
3.2.5 Ground Shaking Characteristics
The United States Geological Survey "National Seismic Hazard Mapping Project"
(1996), a probabilistic study reviewed for this site, incorporates the seismic
characteristics of faults and seismic zones, including fault location and geometry,
slip rate, and magnitude, to develop estimates of ground or bedrock shaking for
different return periods (or probability of exceedance at different time periods).
Large uncertainties exist in the probabilistic analyses due to the lack of significant
historical seismicity and the uncertainty associated with seismic source
characterization. The "National Seismic Hazard Mapping Project" estimated peak
bedrock horizontal accelerations of 0.19g, 0.27g, and 0.39g for return periods of
approximately 500, 1,000, and 2,500 years, respectively.
4. SUBSURFACE EXPLORATION AND CONDITIONS
4.1. Site Exploration
The subsurface soil conditions at the City of Tigard Library site were determined based on
the literature review, field exploration and laboratory testing. The field exploration was
completed on April 23, 2002 and consisted of two exploratory borings, four dilatometer
soundings and one seismic cone penetration sounding. The borings and soundings were
completed in the approximate locations shown in Figure 2, Site Plan.
4.1.1. Borings
Two borings, located within the proposed building footprint, were advanced to depths
of approximately 51.5 feet bgs. The borings were completed with a Mobile B-53 drill
rig equipped with mud rotary capabilities. A member of Geocon Northwest's
geotechnical engineering staff logged the subsurface conditions encountered within
each boring. Standard penetration tests (SPT) were performed at regular intervals by
driving a 2-inch outside diameter split spoon sampler 18 inches into the bottom of
the boring, in general accordance with ASTM D 1586. The number of blows to drive
the sampler the last 12 of the 18 inches are reported on the boring logs located in
Appendix A at the end of this report. Disturbed bag samples were obtained from the
SPT testing and returned to the soils laboratory for evaluation. Service providers
subcontracted by Geocon Northwest completed the drilling.
P1150-05-01 -4- May 10, 2002
Exploration logs describing the subsurface conditions encountered within the borings
are presented in Appendix A at the end of this report.
4.1.2. Cone Penetration Test
The cone penetration test is an in situ testing technique that provides an effective
method of delineating subsurface stratigraphy in areas of clays, silts, sands and fine
gravel. The testing equipment consists of a 35.6-mm diameter cone equipped with a
load cell, friction sleeve, strain gages, porous stone, and geophone. As the cone is
hydraulically pushed at a rate of 2 cm/sec, an electronic data acquisition system
records the tip resistance, sleeve friction, and pore pressure at 0.1-meter intervals.
_ This technique provides a nearly continuous profile of the subsurface conditions
encountered. Additionally, at selected depths, the advancement of the cone can be
suspended and pore water dissipation rates can be measured. Shear waves can be
generated at the ground surface and the travel time for the wave to reach the
geophone located within the cone recorded. Data from the CPT is used for both
shallow and deep foundation design, and liquefaction analyses. The ratio of the
sleeve friction to the tip resistance (the friction ratio) provides soil classification
information.
At this site a CPT sounding was advanced to a depth of approximately 50 feet below
the ground surface. The cone tip resistance and sleeve friction readings were
recorded every four inches along the length of each sounding. A shear wave was
generated at the ground surface at one-meter intervals within the upper thirty feet of
the sounding and at two-meter intervals from 30 to 50 feet. The travel time for each
shear wave to reach the cone tip was recorded. A shear wave velocity profile was
developed for the site and is provided, with logs of cone tip resistance, in Appendix
B.
4.1.3. Dilatometer Test
The dilatometer test provides a rational, cost-effective method to determine
engineering parameters for the design of earthworks and structural foundations. It is
particularly useful in silts and sands that can be difficult to sample or test by other
methods. The DMT is performed in situ by pushing a blade-shaped instrument into
the soil. The blade is equipped with an expandable membrane on one side that is
pressurized until the membrane moves horizontally into the surrounding soil.
Readings of the pressure required to move the membrane to a point that is flush with
the blade (A — pressure) and to a point 1.1 mm into the surrounding soil (B —
P1150-05-01 -5- May 10, 2002
pressure) are recorded. The pressure is subsequently released and, in permeable
soils below the groundwater table, a pressure reading is recorded as the membrane
returns to the flush position (C — pressure). In addition, the thrust required to
advance the blade to the desired test depth is recorded. The test sequence is
performed at 0.2-meter intervals to obtain a comprehensive soil profile. A material
index (ID), a horizontal stress index (KD) and a dilatometer modulus (ED) are obtained
directly from the dilatometer data.
Marchetti (1980) developed a soil classification system based on the material index.
According to this system, soils with ID values less than 0.35 are classified as clay.
Soils classified as sand have an ID value greater than 3.3. Material index values
_ between 0.35 — 3.3 indicate silty clay to silty sand soils. In general, the soils at the
Tigard Library fall within the 0.35 to 3.3 range of silty clay to silty sand soils.
Empirical relationships between the horizontal stress index and the coefficient of
lateral earth pressure (K0) have been developed by Lunne et al. (1990) for clays and
_ by Schmertmann (1983) for uncemented sands. While Lunne's method makes use
of dilatometer data exclusively, Schmertmann utilizes both DMT and cone
penetration data to estimate Ko.
Since the DMT is strained controlled, the measured difference between the B-
pressure and A-pressure readings (corrected for membrane stiffness) and cavity
expansion theory, can be used to directly measure the soil stiffness. Assuming a
Poisson's ratio, the dilatometer modulus is correlated to shear modulus, Young's
modulus and constrained modulus.
The dilatometer soundings completed at this site were advanced to depths ranging
from approximately 30 feet below the ground surface to approximately 50 feet below
the ground surface. A member of Geocon Northwest's engineering staff recorded
the thrust and pressure readings every eight inches along the length of the
soundings. Logs of the dilatometer soundings performed at this site are provided in
Appendix B at the end of this report.
4.2. Subsurface Conditions
The subsurface explorations were widely spaced across the site and it is possible that some
local variations and possible unanticipated subsurface conditions exist. Based on the
conditions observed during the reconnaissance and field exploration, the subsurface
conditions, in general, consisted of the following:
P1150-05-01 -6- May 10, 2002
TOPSOIL — Approximately six to eight inches of organic topsoil was encountered in the
boring and sounding locations.
SANDY SILT TO SILTY SAND— In general, a medium stiff to stiff, fine-grained sandy silt
with occasional layers of silty fine-grained sand was encountered below the topsoil layer.
This deposit extended to a depth of approximately 25 feet below the ground surface.
SILT TO SILTY CLAY — Below the sandy silt, a deposit of stiff to very stiff silt to silty clay
was encountered.
SAND — Borings were terminated in a deposit of dense silty sand with varying percentages
of fine gravel. The dense sand deposit was encountered at a depth of approximately 44 to
—
46 feet below the ground surface.
GROUNDWATER —Groundwater was measured at a depth of approximately nine feet
below the ground surface in Boring B-1.
Subsurface conditions encountered during the field investigation appear to be consistent
with geologic conditions mapped within the region.
5. LABORATORY TESTING
Laboratory testing was performed on selected soil samples to evaluate moisture content,
_ compaction characteristics, California Bearing Ratio, and grain size distribution. Visual soil
classification was performed both in the field and laboratory, in general accordance with the
Unified Soil Classified System. Moisture content determinations (ASTM D2216) were
— performed on soil samples to aid in classifying the soil. Compaction characteristics and the
California Bearing Ratio for near surface samples were evaluated in substantial accordance
with ASTM D1557 and ASTM D1883, respectively. Grain size analyses were performed on
selected samples using procedures ASTM D1140 and ASTM D422.
"' Moisture contents are indicated on the boring logs, which are located in Appendix A of this
report. Other laboratory test results for this project are summarized in Appendix C.
6. CONCLUSIONS AND RECOMMENDATIONS
— 6.1. General
6.1.1. It is our opinion that the proposed project is geotechnically feasible, provided the
— recommendations of this report are followed. It is recommended that the project
P1150-05-01 -7- May 10, 2002
budget include costs for wet weather construction, regardless of the time of year
construction is scheduled to occur. Extra costs associated with wet weather
construction may include overexcavation of soft soils, geotextile separator fabric,
crushed rock backfill, and use of crushed rock for structural fills.
6.1.2. Moisture contents of near-surface soils were wet of optimum at the time of the
investigation. Recommendations for both dry- and wet-weather construction in
moisture-sensitive soils are provided, however, dry weather construction at this site
is recommended. If construction occurs during wet weather, substantial increases
in earthwork costs should be anticipated. Topsoil stripping and removal of existing
underground improvements will be required prior to construction.
6.2. Site Preparation
6.2.1. Prior to beginning construction, the areas of the site to receive fill, footings or
pavement should be stripped of vegetation, topsoil, non-engineered fill, previous
subsurface improvements, debris, and otherwise unsuitable material, down to firm
native soil. Stripping depths of up to 6 to 8 inches should be anticipated.
Excavations made to remove previous subsurface improvements should be
backfilled with structural fill per Section 6.4 of this report.
6.2.2. Recommendations for both dry weather and wet weather site preparation are
provided in the following sections. However, due to the moisture sensitive near-
surface soils, it is recommended that the site be prepared during dry weather.
6.2.3. Dry Weather Site Preparation
Subgrades in pavement and structural areas that have been disturbed during
stripping or cutting operations should be scarified to a depth of at least eight
inches. The scarified soil should be moisture conditioned as necessary to achieve
the proper moisture content, then compacted to at least 92% of the maximum dry
density as determined by ASTM D-1557. Minimum compaction for the eight inches
immediately underlying pavement sections should be 95%. Even during dry
weather it is possible that some areas of the subgrade will become soft or may
"pump," particularly in poorly drained areas. Soft or wet areas that cannot be
effectively dried and compacted should be prepared in accordance with Section
6.2.4.
P1150-05-01 -8- May 10, 2002
—
6.2.4. Wet Weather Site Preparation
— During wet weather, or when adequate moisture control is not possible, it may be
necessary to install a granular working blanket to support construction equipment
and provide a firm base on which to place subsequent fills and pavements.
—
Commonly, the working blanket consists of a bank run gravel or pit run quarry rock
(six to eight inch maximum size with no more than 5% by weight passing the US
-' Sieve No. 200). A member of Geocon Northwest's engineering staff should be
contacted to evaluate the suitability of the material before installation.
The working blanket should be installed on a stripped subgrade in a single lift with
trucks end-dumping off an advancing pad of granular fill. It should be possible to
strip most of the site with careful operation of track-mounted equipment. However,
during prolonged wet weather, or in particularly wet locations, operation of this type
— of equipment may cause excessive subgrade disturbance. In some areas final
stripping and/or cutting may require the use of a smooth-bucket trackhoe, or similar
equipment, working from an advancing pad of granular fill. After installation, the
working blanket should be compacted by a minimum of four complete passes with
a moderately heavy static steel drum or grid roller. It is recommended that Geocon
— Northwest be retained to observe granular working blanket installation and
compaction.
The working blanket must provide a firm base for subsequent fill installation and
compaction. Past experience indicates that about 18 inches of working pad is
normally required. This assumes that the material is placed on a relatively
undisturbed subgrade prepared in accordance with the preceding
recommendations. Areas used as haul routes for heavy construction equipment
may require a work pad thickness of two feet or more.
In particularly soft areas, a heavy-grade, non-woven, non-degradable filter fabric
installed on the subgrade may reduce the thickness of working blanket required.
Construction practices can affect the amount of work pad necessary. By using
tracked equipment and special haul roads, the work pad area can be minimized.
The routing of dump trucks and rubber tired equipment across the site can require
extensive areas and thicknesses of work pad. Normally, the design, installation
and maintenance of a work pad are the responsibility of the contractor.
r
P1150-05-01 -9- May 10, 2002
Lime or cement treatment may be a suitable alternative wet-weather site
preparation technique for the subgrade conditions encountered at this site.
Successful lime or cement treatment is dependent upon moisture content of the
subgrade soils, weather conditions at the time of treatment, and adequate mixing
of the soil and lime or cement. Cement or lime treatment design is typically the
responsibility of the contractor.
6.3. Proof Rolling
Regardless of which method of subgrade preparation is used (i.e. wet weather or dry
weather), it is recommended that, prior to structural fill, on-grade slab, or pavement
construction, the subgrade or granular working blanket be proof-rolled with a fully-loaded
10- to 12-yard dump truck. Areas of the subgrade that pump, weave or appear soft or
muddy should be scarified, dried and compacted, or overexcavated and backfilled with
structural granular fill per Section 6.4. If a significant length of time passes between site
preparation and commencement of construction operations, or if significant traffic has been
routed over these areas, the subgrade should be similarly proof-rolled before fill, slab-on-
grade, or pavement construction begins. It is recommended that a member of our
geotechnical engineering staff observe the proof-roll operation.
6.4. Fills
It is anticipated that the proposed development will consist primarily of on-grade
improvements. . The following sections are presented in the event that minor fills are
required.
6.4.1 Structural fills should be constructed on a subgrade that has been prepared in
accordance with the recommendations in Section 6.2 of this report. Structural fills
should be installed in horizontal lifts not exceeding about eight inches in thickness,
and should be compacted to at least 92% of the maximum dry density for the
native silt soils, and 95% for imported granular material. Compaction should be
referenced to ASTM D-1557 (Modified Proctor). The compaction criteria may be
reduced to 85% in landscape, planter or other non-structural areas.
6.4.2 Dry Weather Fill Construction
During dry weather when moisture control is possible, structural fills may consist of
native material, free of topsoil, debris and organic matter, which can be compacted
to the preceding specifications. However, if excess moisture causes the fill to
pump or weave, those areas should be scarified and allowed to dry, and then be
P1150-05-01 - 10- May 10, 2002
recompacted, or removed and replaced with compacted granular fill as discussed
in Section 6.4.3. of this report.
The native, non-organic sandy silt would generally be acceptable for structural fills
during dry weather if properly moisture conditioned. Near-surface moisture
contents at the time of the field investigation ranged from approximately 25.0% to
36.3%. Lab tests indicate that the optimum moisture content for the near-surface
sandy silt soil is approximately 15.5% at a maximum dry density of approximately
113.5 pcf.
6.4.3 Wet Weather Fill Construction
During wet-weather grading operations, Geocon Northwest, Inc. recommends that
fills consist of well-graded granular soils (sand or sand and gravel) that do not
contain more than 5% material by weight passing the No. 200 sieve. In addition, it
is usually desirable to limit this material to a maximum six inches in diameter for
— future ease in the installation of utilities. Imported granular fill should be
compacted to at least 95% of the maximum dry density as determined by ASTM D
1557.
6.5. Surface and Subsurface Drainage
6.5.1. During site contouring, positive surface drainage should be maintained away from
foundation and pavement areas. Additional drainage or dewatering provisions may
be necessary if soft spots, springs, or seeps are encountered in subgrades.
Where possible, surface runoff should be routed independently to a storm water
— collection system.
6.5.2. Drainage systems should be sloped to drain by gravity to a storm sewer or other
positive outlet.
6.5.3. Drainage and dewatering systems are typically designed and constructed by the
contractor. Failure to install necessary subsurface drainage provisions may result
in premature foundation or pavement failure.
6.6. Foundations
6.6.1. Spread and perimeter foundation support for proposed structures may be obtained
— from the near-surface, firm, non-organic silt soil or from structural fill installed in
P1150-05-01 - 11 - May 10, 2002
accordance with our recommendations. Should footing subgrade elevations
coincide with naturally occurring soft layers, over-excavation to firm soils may be
required. The over-excavation should be backfilled with crushed rock in
accordance with Section 6.4.3.
6.6.2. Spread and perimeter footings should be at least 12 inches wide and should
extend at least 18 inches below the lowest adjacent pad grade. Based on
estimated maximum column loads of approximately 200 kips, foundations that are
supported on firm native soils or engineered fill may be designed for an allowable
soil bearing pressure of 3,000 pounds per square foot (psf).
6.6.3. Gravel or lean concrete may need to be placed in the bottom of the footing
excavation to reduce soil disturbance during foundation forming and construction.
6.6.4. The allowable bearing pressure given above may be increased by one-third for
short term transient loading, such as wind or seismic forces.
6.6.5. Lateral loads may be resisted by sliding friction and passive pressures. A base
friction of 40% of the vertical load may be used against sliding. An equivalent fluid
weight of 350 pcf may be used to evaluate passive resistance to lateral loads.
6.6.6. Foundation settlements for the loading conditions expected for this project are
estimated to be less than one inch, with not more than one-half inch occurring as
differential settlement.
6.6.7. Perched groundwater may be encountered at variable and unexpected locations
and depths. Geocon Northwest recommends that foundation drains be installed at
or below the elevation of perimeter footings to intercept potential subsurface water
that may migrate under the building pad.
6.7. Concrete Slabs-on-Grade
6.7.1. Subgrades in floor slab areas should be prepared in accordance with Section 6.2
of this report. Floor slab areas should be proof-rolled with a fully loaded 10- to 12-
yard dump truck to detect areas that pump, weave, or appear soft or muddy.
When detected these areas should be overexcavated and stabilized with
compacted granular fill.
P1150-05-01 - 12- May 10, 2002
6.7.2. A minimum six-inch thick layer of compacted 3/4-inch minus material should be
installed over the prepared subgrade to provide a capillary barrier and to minimize
subgrade disturbance during construction. The crushed rock or gravel material
should be poorly-graded, angular and contain no more than 5% by weight passing
the No. 200 Sieve.
6.7.3. A modulus of subgrade reaction of 100 pci is recommended for design.
6.7.4. The fine-grained near-surface soils at the site have high natural moisture contents
and low permeability. These characteristics indicate that high ground moisture
may develop under floor slabs during the life of the project. The difference in
moisture content and temperature between the air in the subgrade soil and the air
in the finished building may create a water vapor pressure differential between the
two environments. This pressure differential can force migration of moisture
through the slab. This migration of moisture can result in the loosening of flooring
materials attached with mastic, the warping of wood flooring, stained concrete, and
in extreme cases, mildewing of carpets and building contents. To retard the
migration of moisture through the floor slab, Geocon Northwest recommends
installing a 10-mil polyethylene vapor retarding membrane below the concrete slab.
Installation of the membrane should be in conformance with product
manufacturer's specifications. A minimum 6-inch under-slab section of crushed
rock, as recommended in Section 6.7.2, should be placed as a capillary break
above the subgrade and below the vapor retarder. Any moisture that has
accumulated on the vapor retarding membrane should be removed prior to the
concrete pour. Concrete with a minimum compressive strength of 4000 psi and a
water/cement ratio of less than 0.48 is recommended. In the absence of freezing
temperatures, wet curing of the concrete slab is recommended.
6.8. Retaining Walls and Lateral Loads
6.8.1. The tables presented in the following sections summarize the recommendations for
design of retaining structures. These values represent estimates of the long-term
pressures that will develop in an active or at-rest state of stress. These values do
not include an allowance for hydrostatic pressures and assume that retaining
structures will be provided with a drainage system in accordance with subsequent
sections of this report. The design parameters in the following sections are for
conventional retaining walls and do not include a factor of safety. They also do not
include loading from traffic or other surcharges.
P1150-05-01 - 13- May 10, 2002
6.8.2. Restrained walls are those that are prevented from rotating more than 0.001 H
(where H equals the height of the retaining wall portion of the wall in feet) at the top
—
of the wall. Most basement walls and walls that are rigidly connected to buildings
or that make sharp bends fall into this category. Restrained walls should be
designed for pressures derived from the criteria provided in Table 1.
Table 1: Restrained Wall Design Criteria
r
Backfill Slope Equivalent Fluid
— Weight
H:V
lb/ft3
Level 60
3H:1V 80
2H:1V 105
6.8.3. Non-restrained walls are not restrained at the top and are free to rotate about the
base. Most cantilever retaining walls fall into this category. Non-restrained walls
should be designed for pressures derived from the criteria provided in Table 2.
Table 2: Non-Restrained Wall Design Criteria
Backfill Slope Equivalent Fluid
Weight
H:V
I b/ft3
Level 40
3H:1V 50
—
2H:1V 65
P1150-05-01 - 14- May 10, 2002
6.8.4. Retaining wall backfill should consist of free-draining granular material. To
minimize pressures on retaining walls, the use of open-graded crushed rock
— backfill with less than 5% by weight passing the No. 200 Sieve is recommended.
Retaining wall backfill should be compacted to 90% of ASTM D1557. Backfill,
within approximately five feet of retaining structures, should be compacted with
lightweight hand operated equipment. Use of other material and/or over-
compaction of the backfill could increase wall pressures.
6.8.5. If backfill is in direct contact with the wall, pressures against the back of the wall
—
can be assumed to act at a downward inclination of 20 degrees from the
horizontal. If friction is prevented by drainage membranes or water proofing
membranes, the pressures should be assumed to act horizontally.
6.8.6. Foundations or major loads should not be placed in a zone that extends back from
— the base of a retaining wall ata 1 H:1 V slope.
— 6.8.7. Retaining walls should be provided with drainage in order to alleviate lateral
hydrostatic pressures that may accumulate behind the wall. Retaining wall drains
should be positioned near the base of the retaining wall and should be protected
by a filter fabric to prevent internal soil erosion and potential clogging.
_ 6.8.8. The recommendations presented above are generally applicable to the design of
rigid concrete or masonry retaining walls having a maximum height of 10 feet. In
the event that walls higher than 10 feet or other types of walls are planned,
Geocon Northwest should be consulted for additional recommendations.
6.9. UBC Design Criteria
For buildings designed in accordance with the current Uniform Building Code (UBC) a soil
characteristic called "Soil Profile Type" is used to account for the effect of the underlying soil
conditions on bedrock motion.
Based on the Seismic Rehabilitation Guidelines published by the Federal Emergency
Management Agency (FEMA), where reliable shear wave velocity data are available for a
—
site, such data should be used to classify the site. The soil shear wave velocity determined
from the seismic cone penetrometer test was used to develop the average soil shear wave
— velocity within the upper 100 feet of the site. The shear wave velocity profile of the upper
50 feet, measured at the site, is shown in the shear wave velocity profile provided in
Appendix A. The average shear wave velocity from 50 to 100 feet was extrapolated from
P1150-05-01 - 15- May 10, 2002
—
the shear wave velocity recorded at the site at 50 feet below the ground surface and on
shear wave data provided in Open File Report 0-95-7 published by the State of Oregon
Department of Geology and Mineral Industries. Based on this information, the
calculated average soil shear wave velocity within the upper 100 feet, determined in
accordance with the procedures outlined in UBC Section 1636 "Site Categorization
Procedure", was approximately 825 feet per second. An average shear wave velocity
between 600 feet per second and 1200 feet per second places the site within Soil Profile
Type SD. It is recommended that a seismic zone factor of 0.3 for UBC Zone 3 be used for
structural seismic analysis of the proposed building. Seismic design coefficients of Ca equal
— to 0.36 and C, equal to 0.54 are recommended based on Soil Profile Type SD.
6.10. Excavation Characteristics
6.10.1. Based on the subsurface explorations, difficult excavation characteristics are not
anticipated.
6.10.2. Excavations deeper than four feet, or those that encounter groundwater, should be
—
sloped or shored in conformance with OSHA regulations. Shoring systems are
typically contractor designed.
6.10.3. Groundwater was encountered at approximately nine feet below the ground
surface during the field investigation. Perched groundwater at shallower depths
—
may occur in variable locations within the fine grained materials observed near the
surface. Excavation dewatering may be necessary if substantial flow of
— groundwater is encountered. Dewatering systems are typically designed and
installed by the contractor.
6.11. Pavement Design
-- 6.11.1. Near surface soil samples were evaluated to determine pavement design
parameters. A CBR of 3 at 95% compaction and a resilient modulus of 4,500
were used for pavement design.
_
6.11.2. Alternate pavement designs for both asphalt and portland cement concrete (pcc)
are presented in Tables 3 and 4. Pavement designs have been prepared in
accordance with accepted AASHTO design methods. A range of pavement
_ designs for various traffic conditions is provided in the tables. The designs assume
that the top eight inches of pavement subgrade will be compacted to 95% ASTM
D-1557. Specifications for pavement and base course should conform to current
Oregon State Department of Transportation specifications. Additionally, the base
P1150-05-01 - 16- May 10, 2002
rock should contain no more than 5% by weight passing a No. 200 Sieve, and the
asphaltic concrete should be compacted to a minimum of 91% of ASTM D2041.
Table 3: Asphalt Concrete Pavement Design
Approx. Approx. Asphalt Crushed Rock
Number of Number of 18 Concrete Base Thickness
Trucks per Day Kip Design Axle Thickness (inches)
(each way) Load (1000) (inches)
Auto Parking 10 2.5 8
5 22 3.0 8
10 44 3.0 10
15 66 3.5 10
25 110 4.0 10
50 220 4.0 12
100 440 4.5 12
150 660 5.0 13
Table 4: Portland Cement Concrete Pavement Design
Approx. Approx. P.C.C. Crushed Rock
Number of Number of 18 Thickness Base Thickness
Trucks per Day Kip Design Axle (inches) (inches)
(each way) Load (1000)
25 110 6.0 6
—
50 220 7.0 6
100 440 8.0 6
150 660 8.5 6
200 880 8.5 6
250 1100 9.0 6
Pavement sections were designed using AASHTO design methods, with an
assumed reliability level (R) of 90%. Terminal serviceability of 2.0 for asphaltic
concrete, and 2.5 for portland cement concrete were assumed. The 18 kip design
axle loads are estimated from the number of trucks per day using State of Oregon
typical axle distributions for truck traffic and AASHTO load equivalency factors, and
assuming a 20 year design life. The concrete designs were based on a modulus of
P1150-05-01 - 17- May 10, 2002
rupture equal to 550 psi, and a compressive strength of 4000 psi. The concrete
sections assume plain jointed or jointed reinforced sections with no load transfer
devices at the shoulder.
_ 6.11.3. If possible, construction traffic should be limited to unpaved and untreated
roadways, or specially constructed haul roads. If this is not possible, the pavement
design should include an allowance for construction traffic.
7. FUTURE GEOTECHNICAL SERVICES
The analyses, conclusions and recommendations contained in this report are based on site
conditions as they presently exist, and on the assumption that the subsurface investigation
locations are representative of the subsurface conditions throughout the site. It is the nature
-- of geotechnical work for soil conditions to vary from the conditions encountered during a
normally acceptable geotechnical investigation. While some variations may appear slight,
_ their impact on the performance of structures and other improvements can be significant.
Therefore, it is recommended that Geocon Northwest be retained to observe portions of this
project relating to geotechnical engineering, including site preparation, grading, compaction,
-- foundation construction and other soils related aspects of construction. This will allow
correlation of observations and findings to actual soil conditions encountered during
construction and evaluation of construction conformance to the recommendations put forth
in this report.
A copy of the plans and specifications should be forwarded to Geocon Northwest so that
they may be evaluated for specific conceptual, design, or construction details that may
affect the validity of the recommendations of this report. The review of the plans and
specifications will also provide the opportunity for Geocon Northwest to evaluate whether
the recommendations of this report have been appropriately interpreted.
8. LIMITATIONS
Unanticipated soil conditions are commonly encountered during construction and cannot
always be determined by a normally acceptable subsurface exploration program. The
recommendations of this report pertain only to the site investigated and are based upon the
assumption that the soil conditions do not deviate from those disclosed in the investigation.
If variations or undesirable conditions are encountered during construction, or if the
P1150-05-01 - 18- May 10, 2002
proposed construction will differ from that anticipated herein, Geocon Northwest should be
notified so that supplemental recommendations can be given.
This report is issued with the understanding that the owner, or his agents, will ensure that
the information and recommendations contained herein are brought to the attention of the
architect and engineer for the project and incorporated into the plans and specifications.
The findings of this report are valid as of the present date. However, changes in the
conditions of a property can occur with the passage of time, whether they be due to natural
processes or the works of man on this or adjacent properties. In addition, changes in
applicable or appropriate standards may occur, whether they result from legislation or the
broadening of knowledge. Accordingly, the findings of this report may be invalidated wholly
or partially by changes outside our control. Therefore, this report is subject to review should
such changes occur.
If you have any questions regarding this report, or if you desire further information, please
contact the undersigned at (503) 626-9889.
GEOCON NORTHWEST, INC.
z C, -
Heather Devine, P.E. Wesley Spang, Ph.D., P.E.
Geotechnical Engineer President
P1150-05-01 - 19- May 10, 2002
REFERENCES
Andrews, D.C., Martin, G.R., 2000, Criteria for Liquefaction of Silty Soils, World Conference
on Earthquake Engineering.
-- Lunne, T., Robertson, P.K., Powell, J.J.M., 1997, Cone Penetration Testing In Geotechnical
Engineering Practice, E & FN Spon Publishers.
Mabey, M. A., Madin, I.P., 1995, Open-File-Report 0-95-7, "Downhole and Seismic Cone
Penetrometer Shear-Wave Velocity Measurements for the Portland Metropolitan
Area, 1993 and 1994," Oregon Department of Geology and Mining Industries.
Marchetti, S., 1980, "In Situ Tests by Flat Dilatometer,: Journal of Geotechnical Engineering,
ASCE, Vol. 106, No. GT3, Proc. Paper 15290, March, pp 299-321
National Center For Earthquake Engineering Research, 1997, "Proceedings of the NCEER
Workshop on Evaluation of Liquefaction Resistance of Soils," Technical Report
— NCEER 97-0022.
Oregon Department of Geology and Mineral Industries, 1994, Open-File Report 0-94-4.
Schmertmann, J.H., 1983, "DMT Digest No. 1," Internal Report of GPE Inc., April
Seed, H.B., and Idriss, I.M., 1982 Ground Motions and Soil Liquefaction During
— Earthquakes, Earthquake Engineering Research Institute. •
Stark, T.D., Olson, S.M., 1995, "Liquefaction Resistance Using CPT and Field Case
Histories," Journal of Geotechnical Engineering, Vol. 121, No. 12.
— United States Geologic Survey, 1996, "National Seismic Hazard Mapping Project."
http://geohazards.cr.usgs.gov/eq/.
I
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PROJECT NO. P1150-05-01
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REPRODUCED WITH PERMISSION GRANTED BY THOMAS BROTHERS MAPS. N
THIS MAP IS COPYRIGHTED BY THOMAS BROS.MAPS.IT IS UNLAWFUL TO COPY "`111
OR REPRODUCE ALL OR ANY PART THEREOF.WHETHER FOR PERSONAL USE OR
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GEOCON �( VICINITY MAP
NOR TIT WES T ��
CITY OF TIGARD LIBRARY
— GEOTECHNICAL CONSULTANTS TIGARD OREGON
8380 SW NIMBUS AVENUE . BEAVERTON,OREGON 97008 r
PHONE 503 626-9889 - FAX 503 626-8611
HD/RSS DSK/D000D DATE 5/13/02 PROJECT NO. P1150-05-01 FIG. 1
ORVIC
APPENDIX A
FIELD INVESTIGATION
BORINGS
The borings were completed April 23, 2002, and were advanced to an approximate depth of
51.5 feet below the ground surface. The approximate locations of borings are shown in
Figure 2.
The borings were advanced with a Mobile B-53 drill rig equipped with mud rotary
capabilities. Standard penetration tests (SPT) were conducted at regular intervals within the
borings. Disturbed bag samples were collected with a split spoon sampler and returned to
the laboratory for further testing.
Subsurface logs of the conditions encountered are presented in the following pages. Both
solid and dashed contact lines indicated on the logs are inferred from soil samples and
drilling characteristics, and should be considered approximate.
PROJECT NO. P1150-05-01
ce
BORING B 1 Z „ }
W
DEPTH 0 I-
H°I- H^ W'
SAMPLE OJ 30 SOIL F-¢W ��
-. FEET NO. = CLASS ELEV. (MSL.) DATE COMPLETED 4/23/02 ce�t�n w� �z
H O (USCS) I- 03O FIW
J CD EQUIPMENT B53 -MUD ROTARY I?ILI w m >-° E o
o-�.' 0 0
MATERIAL DESCRIPTION
- 30 - B1-9 1 MLI 30.6
Very stiff, saturated, gray, SILT, trace fine-grained
sand
- 32 -
- 34 -
B1-10 li.-I - CL Medium stiff, saturated, gray, Silty CLAY 8 31.3
- 36 - -f I-
- 38 - -1:1 _�
- 40 -
B1-11
1--i -I -Becomes very stiff 16 27.4
- 42 - _1 �"
- 44 -
-11: E.
- -B1-12 -"1-. 35 24.9
- - 46 - '
Dense, saturated, Silty, coarse-grained SAND to fine
T SW GRAVELIII
- 48 -
- 50 - Very stiff to hard, saturated, gray, fine-grained
B1-13 _ ML Sandy SILT, occasional to some coarse sand to fine 33 24.8
- - �'_" - gravel
BORING TERMINATED AT 51.5 FEET
Groundwater Measured At Approximately 9 Feet
- Figure A-2, Log of Boring B 1 TL
SAMPLE SYMBOLS 0 ... SAMPLING UNSUCCESSFUL C ... STANDARD PENETRATION TEST II ... DRIVE SAMPLE (UNDISTURBED)
-
=•= ... DISTURBED OR BAG SAMPLE 1-61 ... CHUNK SAMPLE Y ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. P1150-05-01
LU BORING B 1 z ^ } ^
W
DEPTH J 3 SOIL HUF- H^ ,......1-d•-'
SAMPLE O 0 '<C U
IN NO. = CLASS ELEV. (MSL.) DATE COMPLETED 4/23/02 ce¢ccn wd ti)
FEET H O (USCS) HH3 pU HW
Li1 MOLa EQUIPMENT B53 -MUD ROTARY w w m >-, E o
CL •-• O U
-
MATERIAL DESCRIPTION
- 0 _
Approximately 6-inches TOPSOIL
- 2 - _
Medium dense, moist, mottled, Silty, fine-grained
- - B1-1 11 -t SP SAND - 22 25.0
-
_ 4 _ f _
B1-2 _1 •-
_
- 6 - 1-.1 I -
-
B1-3 -i f I SM 3 35.9
- 8 - _ �_� Soft, wet, brown, fine-grained Sandy SILT _
- _ _ .-1- _
1.
- 10 _ B1-4 IEII 1-
-
12 B1-5 -i 1 Medium stiff, saturated, brown, fine-grained Sandy 6 41.7
- - 1 -1 SILT, some clay -
- 14 - : l -
- - Irl _
B1-6 i 1 SM Medium dense, saturated, brown, Silty, fine-grained 11 31.9
_ - 16 - _1-_I i SAND -
- 18 - i - - -
- - -
--1.-._1_
- 20 - i- 1 -
- B1-7r_.1 -. - Medium stiff, wet, brown, fine-grained Sandy SILT 7 31.1
-
- 22 - -1--1 1 _
- - i
_if I- -
- 24 - _-1 I- -
- -
B1-8 [ ML Very stiff, saturated, gray, SILT, trace fine-grained 17 35.4
- 26 - sand -
- 28 - _
• Figure A-1, Log of Boring B 1 TL
SAMPLE SYMBOLS 0 ... SAMPLING UNSUCCESSFUL 1111 ... STANDARD PENETRATION TEST U ... DRIVE SAMPLE (UNDISTURBED)
DISTURBED OR BAG SAMPLE Q ... CHUNK SAMPLE 3E ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. P1150-05-01
I- BORINGB2 z }
W
DEPTH ¢ HUI- H^ ,..1.\
SAMPLE p SOIL
1_.....1. U • r,..`""-,
IN NO = CLASS ELEV. (MSL.) DATE COMPLETED 4/23/02 ce�'cn w •• Hz
FEET 1_,--1, 2 (USCS) I-H3 oU HW
J EQUIPMENT B53 -MUD ROTARY Ct
w w m CC �o
0---,-, O U
MATERIAL DESCRIPTION
- 0
Approximately 8-inches TOPSOIL
- - -__1 il -- -
- 2 -
t I Medium dense, moist, brown to reddish-brown, Silty,
- - B2-1 -1 - fine-grained SAND - 12 26.4
- 4 - 1. II -
- -
6 - B2-2 1 �- -- SP - 6 36.3
i'-.
_1• I Loose, wet, brown, Silty, fine-grained SAND
1fI_ -
- -
- 8 - B2-3 - - _ -
1fI
- 10 B2-4 -
- -Medium dense, wet, brown, Silty, fine-grained _ 11 28.4
- - SAND
- 12 - .I _
- 14 - 1 ( -
- - B2-5 -i -f- -
-
- - 16 - _
- -
- 18 -
B2-6 I -Color change to gray - 16 23.3
i
-
-
- I
20 -
B2-7 -1-f I- 19 30.4
- - -i � � _
22 - 1- I
� I -
-1 -_
- 24 -
- — Stiff, saturated, gray, fine-grained Sandy SILT _
B2-8 SW 17 31.0
- 26 - -
., - 28 - - -
- Figure A-3, Log of Boring B 2 TL
SAMPLE SYMBOLS El ... SAMPLING UNSUCCESSFUL El ... STANDARD PENETRATION TEST El ... DRIVE SAMPLE (UNDISTURBED)
... DISTURBED OR BAG SAMPLE Q ... CHUNK SAMPLE 3E ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
PROJECT NO. P1150-05-01
w BORINGB2 z ^ }
W
DEPTH I-
0J 3 SOIL HZI—• ^ ��
SAMPLE p p I— LL (0
— FEET N0.IN CLASS ELEV. (MSL.) DATE COMPLETED 4/23/02 ceNuu) wc3 �z
H 2 (USCS) 1-H 3 0 H W
EQUIPMENT B53 -MUD ROTARY w w m o
O_X,-, 0 0
MATERIAL DESCRIPTION
—
30 B2 9 28 25.0
-Becomes very stiff
32 — - SM —
— — 34 — —
— 36 —
B2-10 L Very stiff, saturated, gray, SILT _ 33 24.7
— 38 — ML _
— 40 — '
B2-11 17 35.3
— 42 — —
—
— 44 —
1 Dense, saturated, gray, Silty, fine-grained SAND _
B2-12 i-fE- 36 34.9
— 46 — j '-I -
— — -1-
:I_�- SM _
— 48 — i- _
—
50 =B2-13 r: I_ �. _ 35 38.8
1
BORING TERMINATED AT 51.5 FEET
Groundwater Was Not Measured
..
- Figure A-4, Log of Boring B 2 TL
SAMPLE SYMBOLS El ... SAMPLING UNSUCCESSFUL in ... STANDARD PENETRATION TEST U ... DRIVE SAMPLE (UNDISTURBED)
Al
DISTURBED OR BAG SAMPLE Q ... CHUNK SAMPLE 3E ... WATER TABLE OR SEEPAGE
NOTE: THE LOG OF SUBSURFACE CONDITIONS SHOWN HEREON APPLIES ONLY AT THE SPECIFIC BORING OR TRENCH LOCATION AND AT THE
DATE INDICATED. IT IS NOT WARRANTED TO BE REPRESENTATIVE OF SUBSURFACE CONDITIONS AT OTHER LOCATIONS AND TIMES.
APPENDIX B
FIELD INVESTIGATION
IN SITU TESTING
The in situ testing was completed April 23, 2002 and consisted of four dilatometer
—
soundings and one seismic cone penetration sounding.
The cone penetration sounding was advanced in the approximate location shown in Figure
2. Data was recorded every four inches along the length of the sounding. Shear waves
— were introduced at the ground surface at one-meter intervals in the upper 30 feet within the
sounding. Between depths of 30 and 50 feet shear waves were introduced at 2-meter
intervals. Logs of the recorded tip resistance and friction ratio as well as a shear wave
velocity profile are provided in the following pages.
— The dilatometer soundings were advanced in the approximate locations shown in Figure 2.
A member of Geocon Northwest's geotechnical engineering staff recorded dilatometer
readings every eight inches along the sounding. Dilatometer data is provided herein.
Tigard Library
rar
y
Oporatoc W.MCC/A.MEE CPT Date/Time: 04-23-02 15:03
Sounding: CPT-1 Location: Tigard,Oregon
Cone Used: 457 TC Job Number: P1150-05'01
Tip Resistance Friction Ratio
Qt(Tomft^2) Fs/Qt(%)
�
0.00 800.000.00 7.00
0.00
/ / / / / / 1 1 1 /
5.00 — - -
_~ 10.00 — - -
15.00 — - -
20.00 — - - -
-
25.00 — - -
Depth
ouoo — - -
35.00 —
:::
—
50.00
Maximum
' -------- '
Maomumoepth~4S.e7fee Depth Increment=0.16 fee
Appendix B-1
- New Tigard Library
Shear Wave Velocity Profile
0
i
I I
5 I i
_ ri ,,1
!III
10
Ili illI
I I
I
15
I
I 1
I
I
20
I
_ 1
Q 25
0
30 I II 1
11 1
i
1
i i I
— 35 1
1 I I
'
40 i I
I
—
I I
i
45
i
I 1 1
1
I
s
50 1
1 I
—
400 600 800 1000 1200
Shear Wave Velocity (ft/sec)
Dilatometer D-1 Tigard Library P1150-05-01
Tigard,OR April 26,2002
DMT-1
Modulus M(tsf)
0 500 1000 1500 2000 2500
0
•
10 -
20 -
a
30 -
40
l
50 - •
60 -
Dilatometer D-2 Tigard Library P1150-05-01
Tigard,OR April 26,2002
DMT-2
Modulus M(tsf)
0 200 400 600 800 1000 1200 1400 1600
0
5 -
10 -
15 -
20 -
s 25
m
30 -
35 -
40
45
50
Dilatometer D3 Tigard Library P1150-05-01
Tigard,OR March 20,2002
DMT-3
Modulus M(tsf)
0 500 1000 1500 2000 2500
0
5 -
10 -
15 -
20 -
2
25 -
as
30
35
40 -
45 -
50 -
Dilatometer D-4 Tigard Library P1150-05-01
Tigard,OR April 26,2002
_ DMT-4
Modulus M(tsf)
0 500 1000 1500 2000 2500
5
10 -
15 -
1
a
m
0
20 - >
25 -
30 -
35 -
APPENDIX C
LABORATORY TESTING
_ Laboratory tests were performed in accordance with generally accepted test methods of the
American Society for Testing and Materials (ASTM) or other suggested procedures.
Selected soil samples were tested for their maximum dry density and optimum moisture
content, California Bearing Ratio, in situ moisture content, and grain size distribution.
Moisture contents are indicated on the boring logs in Appendix A. Other results of
laboratory tests performed are summarized in the following pages.
1
— TABLE C-1
SUMMARY OF PLASTICITY INDEX RESULTS
ASTM D 4318
Sample Depth (ft) Liquid Limit Plastic Limit Plasticity Index
No.
B1-5 12-13.5 NP
B1-7 20-21.5 NP
B2-4 10-11.5 NP
— TABLE C-2
MODIFIED PROCTOR RESULTS
ASTM D 1557
— Sample No. Depth Material Description Maximum Dry Optimum
(ft) Density Moisture
(pcf)
Content
—
(% dry wt.)
Composite 1.0—3.5 Sandy Silt 113.5 15.5
CALIFORNIA BEARING RATIO (ASTM D 1883): A CBR value of 3 was used for pavement
design.
I ► 1 i 1 1 I 1 1 I 1 f ► 1 1 I r
Grain Size Distribution (ASTM D1140 and D 422)
Sample B1-5
Depth= 12-13.5 feet
'GRAVEL' SAND
I SILT I CLAY
100 -
I I
I I
- I - - -I.
I I
I I
80 - - -
I I
-' - - _ -
I I
a) 60 -1 - - —r -
3 i 1
az 1 1
at
4 I
40 � �
(9 I I
ai
a I I
I - - - - . -- + - - -
I I
•
20 a i
I I
- - - -
I I
I I
0 , , 1 , ,' , . I , 1 i 1 1 , 1 1 1 - 1 , 1 , , 1 0 , , - , , 1
10 1 0.1 0.01 0.001
Grain size(mm)
► ► ► ► I I I I I I I I I i I I I ••
Grain Size Distribution (ASTM D1140 and D 422)
Sample B1-7
Depth = 20-21.5 feet
I GRAVEL` SAND I SILT I CLAY
100
I I
I
- - .- - _
I I
80 �. _
I I
-I I _ - - - _ —
4 60 I _ _ -
3 I I
pN I _ I
_ - -
t I
2 �
40 ' - - - - - -
1
a I •
I I
I I
• I
20 - s 1
-
1
1 I
1 I
0I
i
10 1 0.1 0.01 0.001
Grain size(mm)
I I I I I 1 I 1 I I I I I 1 ► ► I ► ►
Grain Size Distribution (ASTM D1140 and D 422)
Sample B2-4
Depth = 10-11.5 feet
I GRAVEL I SAND I SILT I CLAY I
100
I II I
I
I I
I I
80 - , - - -- - • - - -
I I
60 1 _ -4--
1
1
b - I - - - I - - - -
aI
a0; 40 - 1 - - - - I -
P-i I I
— - I _ _ _ - -I-- _ - - _
I I
I I
20 . 1
I I N
I I - - —
I I
0 - ' — ' / 1 1 1 .'I I S - - - 1 1 1
10 1 0.1 0.01 0.001
Grain size(mm)