Report (59) AMP
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JUL ! 1018
CITY OF TIGARD
BUILDING DIVISION
Geotechnical Investigation and Consultation Services
Proposed Taco Bell Re-Development Site #15347
Tax Lot No. 1804
13305 SW Pacific Highway
Tigard (Washington County), Oregon
for
Weber Coastal Bells, LLC
opt®
oho
Project No. 1141.010.G
June 29,2018
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.71 ' REDMOND GEOTECHNICAL SERVICES
June 29, 2018
Ms. Lindsay Johnston
Weber Coastal Bells, LLC
840 Conger Street
P.O. Box 23408
Eugene,Oregon 97402
Dear Ms.Johnston:
Re:Geotechnical Investigation and Consultation Services,Tigard Taco Bell Re-Development Site
(#15347),13305 SW Pacific Highway,Tigard(Washington County),Oregon
Submitted herewith is our report entitled"Geotechnical Investigation and Consultation Services,
Tigard Taco Bell Re-Development Site(#15347), 13305 SW Pacific Highway,Tigard(Washington
County),Oregon".The scope of our services was outlined in our formal proposal to Ms. Lindsay
Johnston dated May 22,2018.Written authorization of our services was provided by Ms. Lindsay
Johnston on May 23,2018.
During the course of our investigation,we have kept you and/or others advised of our schedule and
preliminary findings.We appreciate the opportunity to assist you with this phase of the project.
Should you have any questions regarding this report,please do not hesitate to call.
Sincerely, tAVPROF
, I 0 • b:
Daniel M. Redmond, P.E.,G.E. l( a. , F� '�
President/Principal Engineer 0
4,9 is,‘1°- p�
Cc: Mr. Dave Reichert M. Res)
All County Surveyor's&Planners, Inc.
PO Box 20547 • PORTLAND, OREGON 97294 • FAX 503/286-7176 • PHONE 503/285-0598
TABLE OF CONTENTS
Page No.
INTRODUCTION l
PROJECT DESCRIPTION l
SCOPE OF WORK 2
SITE CONDITIONS 3
Site Geology 3
Surface Conditions 3
Subsurface Soil Conditions 3
Groundwater 4
Geologic and Seismic Setting 4
INFILTRATION TESTING 5
LABORATORY TESTING 5
SEISMICITY AND EARTHQUAKE SOURCES 5
Liquefaction 6
Landslides 7
Surface Rupture 7
Tsunami and Seiche 7
Flooding and Erosion 7
CONCLUSIONS AND RECOMMENDATIONS 8
General 8
Site Preparation 8
Foundation Support 9
Conventional Shallow Foundations 10
REDMOND GEOTECHNICAL SERVICES
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Table of Contents (continued)
Floor Slab Support 10
Retaining/Below Grade Walls 11
Pavements 12
Automobile Parking and Access Drives 12
Pavement Subgrade,Base Course and Asphalt Materials 12
Excavations/Slopes 13
Surface Drainage/Groundwater 13
Design Infiltration Rates 13
Seismic Design Considerations 14
EROSION CONTROL 14
CONSTRUCTION MONITORING AND TESTING 15
CLOSURE AND LIMITATIONS 15
LEVEL OF CARE 16
REFERENCES 17
FIGURES
figure No. 1 - Site Vicinity Map
Figure No. 2 - Site Exploration Plan
APPENDIX
Appendix A- Test Pit Logs and Laboratory Test Results
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GEOTECHNICAL INVESTIGATION AND CONSULTATION SERVICES
KENNEWICK TACO BELL RE-DEVELOPMENT SITE (#15347)
13305 SW PACIFIC HIGHWAY
TIGARD(WASHINGTON COUNTY), OREGON
INTRODUCTION
Redmond Geotechnical Services, LLC is please to submit to you the results of our Geotechnical
Investigation at the site of the existing and/or proposed new Taco Bell restaurant which is located to
the west of SW Pacific Highway and south of SW Park Street in Tigard(Washington County), Oregon.
The general location of the subject site,which encompasses approximately 1.1 total acres, is shown
on the Site Vicinity Map, Figure No. 1.
The purpose of our geotechnical investigation services at this time was to explore the existing
subsurface soils and/or groundwater conditions across the subject site and to develop and/or
provide appropriate geotechnical design and construction recommendations for the proposed new
Taco Bell project.
PROJECT DESCRIPTION
We understand that present plans are to re-develop the subject existing Taco Bell site and construct
a new Taco Bell structure at the subject site. Based on a review of the proposed site development
plan prepared by All County Surveyor's and Planners, Inc., we understand that the proposed new
restaurant structure will consist of the construction of an approximate 2,052 square feet building
which will be a total of one(1)story in height.Construction of the proposed new restaurant
structure is anticipated to consist of wood-framing.
Support for the new restaurant structure will include both conventional shallow strip (continuous)
and individual (spread)column footings as well as a concrete slab-on-grade floor.Structural loading
information,although unavailable at this time, is anticipated to result in maximum dead plus live
loads for the continuous(strip)and/or individual (column)footing loads on the order of about 1.5 to
2.0 kips per lineal foot(klf)and 10 to 25 kips, respectively.
Finish floor elevations for the proposed new restaurant building will reportedly be at about
Elevation 485 feet.As such,only minor site grading is anticipated for re-development of the site and
is expected to result in structural cuts and/or fills on the order of about one (1)feet or less.Other
associated site improvements for the new Taco Bell project will include new underground utility
services and landscaping as well as new paved parking and drive areas. Further,we understand that
re-development of the site will include the collection and on-site disposal of storm water.
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Project No. 1141.010.G
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SCOPE OF WORK
The purpose of our geotechnical studies was to evaluate the overall site subsurface soil and/or
groundwater conditions underlying the site with regard to the proposed new Taco Bell structure
construction and development at the site and any associated impacts or concerns with respect to
the new restaurant structure as well as provide appropriate geotechnical design and construction
recommendations for the project.Specifically,our geotechnical investigation included the following
scope of work items:
1. Review of available and relevant geologic maps and/or geotechnical reports for the subject
area.
2.A detailed field reconnaissance and subsurface exploration program of the soil and ground
water conditions underlying the site by means of three(3)exploratory test pits.The
exploratory test pits were advanced to depths of about six(6.0)feet beneath existing site
grades at the approximate locations as shown on the Site Exploration Plan, Figure No.2.
Additionally,field infiltration testing was performed in test hole TH-#2 at a depth of about four
(4)feet.
3. Laboratory testing to evaluate and identify pertinent physical and engineering properties of
the subsurface soils encountered relative to the planned site development and construction
at the site.The laboratory testing program included tests to help evaluate the natural (field)
moisture content and dry density, maximum dry density and optimum moisture content and
gradational characteristics as well as direct shear strength and "R"-value tests.
4.A literature review and engineering evaluation and assessment of the regional seismicity to
evaluate the potential ground motion hazard(s)at the subject site.The evaluation and
assessment included a review of the regional earthquake history and sources such as
potential seismic sources, maximum credible earthquakes,and reoccurrence intervals as
well as a discussion of the possible ground response to the selected design earthquake(s),
fault rupture, landsliding, liquefaction,and tsunami and seiche flooding.
5. Engineering analyses utilizing the field and laboratory data as a basis for furnishing
recommendations for foundation support of the proposed new restaurant structure.
Recommendations include maximum design allowable contact bearing pressure(s),
depth of footing embedment,estimates of foundation settlement, lateral soil resistance, and
foundation subgrade preparation.Additionally,construction and/or permanent subsurface
water drainage considerations have also been prepared. Further,our report includes
recommendations regarding site preparation, placement and compaction of structural fill
materials, suitability of the on-site soils for use as structural fill,criteria for import fill
materials,and preparation of foundation, pavement and/or floor slab subgrades.
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SITE CONDITIONS
Site Geology
Available geologic mapping of the area and/or subject site(Geologic Map of the Beaverton
Quadrangle) indicates that the near surface soils are comprised of fine-grained fades(Qff)of
Pleistocene age.Characteristics include crudely to complexly layered, poorly consolidated medium
sand to silt deposited by one or more phases of catastrophic glacial outburst floods from late
Pleistocene Lake Missoula.Sediments of unit Qff occur along both sides of the Willamette and
Columbia Rivers, locally in the Gladstone-Oregon City area and throughout the Tualatin basin.The
thickness of unit Qff is typically 30 to 60 feet with a maximum thickness in the map area of about
180 feet. Unit Qff sediments were deposited beneath regionally ponded floodwaters the highest of
which reached an elevation of approximately 400 feet above sea level, based on distribution of ice-
rafted erratic(Allison, 1935). However,sediments that are clearly part of unit Qff are typically found
no higher than about 250 to 300 feet above sea level.Ponding of floodwaters to 400 feet above sea
level may not have happened sufficiently often or for a sufficient length of time to allow significant
sediment deposition at higher elevations. It is very difficult to distinguish unit Qff and QI in all but
the best outcrops, hence the contact between the two units is commonly drawn following the 300
foot elevation contour in the absence of site specific data. Evidence of liquefaction is commonly
observed in good exposures of unit Qff in the form of silt dikes that crosscut both bedding and
earlier dikes. It is not clear whether liquefaction occurred during multiple flood events,subsequent
earthquakes,or both.
Surface Conditions
The subject existing and/or proposed new Taco Bell development property is generally rectangular
in shape and encompasses a total area of approximately 1.1 acres.The existing and/or proposed
Taco Bell development property is roughly bounded to the east by SW Pacific Highway and to the
north,south and west by developed commercial properties.The subject existing and/or proposed
new Taco Bell restaurant site is presently improved and consists of an existing restaurant structure
and paved surface improvements as well as buried and/or underground utility services.
Topographically,the site is characterized as gently sloping terrain descending downwards towards
the northeast with overall topographic relief estimated at about ten (10)feet and is estimate to lie
between about Elevation 223 and Elevation 233 feet.
Subsurface Soil Conditions
Our understanding of the subsurface soil conditions underlying the site was developed by means of
three (3)exploratory test pits advanced to depths of about six(6.0)feet beneath existing site grades
on June 14, 2018.The location of the exploratory test pits were located in the field by marking off
distances from existing and/or known site features and are shown in relation to the existing and/or
proposed new Taco Bell structure and/or existing site improvements on the Site Exploration Plan,
Figure No. 2.
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Detailed logs of the test pit explorations, presenting conditions encountered at each location
explored, are presented in the Appendix, Log of Test Pits, Figure No's.A-4 and A-5.
The exploratory test pits were observed by staff from Redmond Geotechnical Services, LLC who
logged each of the test pit explorations and obtained representative samples of the subsurface soils
encountered across the site.Additionally,the elevation of the exploratory test pits were referenced
from an Existing Conditions Plan prepared by All County Surveyors& Planners, Inc. and are
considered as approximate.All subsurface soils encountered at the site and/or within the
exploratory test holes were logged and classified in general conformance with the Unified Soil
Classification System (USCS)which is outlined on Figure No.A-3.
The test pit explorations revealed that the subject site is underlain by native soil deposits comprised
of fine grained facies of Pleistocene age.Specifically,the subgrade soil materials were found to
consist of a surficial layer of topsoil materials composed of dark brown,very moist to wet,soft,
organic,clayey,sandy silt to a depth of about 10 to 12 inches.These surficial topsoil materials were
inturn underlain by medium to olive-brown,very moist to wet,soft to medium stiff, clayey,sandy
silt to the maximum depth explored of approximately 6.0 feet beneath existing site grades.These
underlying clayey,sandy silt subgrade soil deposits,which become medium stiff to stiff at a depth of
about 4 to 5 feet,are best characterized by relatively low to moderate strength and moderate
compressibility.
Groundwater
Groundwater,was not encountered within any of the exploratory test holes at the time of the
exploration work to a depth of at least 6.0 feet beneath existing site grades. However,seasonal
fluctuations of the groundwater table in the area and/or across the subject site should be expected.
Additionally,the presence of the near surface clayey, sandy silt subgrade soils beneath the site
suggests that groundwater could temporarily perch near the ground surface during periods of heavy
and/or prolonged rainfall.
GEOLOGIC AND SEISMIC SETTING
A seismic site-specific hazard study was not part of the scope of work for this project. However, we
have provided IBC design parameters in the recommendations section (Table 1) of this report in the
event that this information is required by others.The liquefaction potential of the foundation soils is
considered negligible due to the cohesive characteristics of the underlying clayey,sandy silt
subgrade soils.
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Project No. 1141.010.G
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INFILTRATION TESTING
To evaluate the feasibility of subsurface disposal of storm water,we were present at the site on
June 14,2018 and performed one (1)field infiltration test(see Figure No.A-10)within test hole
TH-#2 (see Site Exploration Plan, Figure No.2)at a depth of about four(4)feet.The testing consisted
of an encased single-sleeve falling head infiltration test in accordance with current EPA standards
and/or the City of Tigard/Washington County test method.
Specifically,one(1)test hole(TH-#2)was excavated with portable excavation equipment to a depth
of about four(4)feet beneath the existing site and/or surface grades.The subgrade soils
encountered within the test hole excavated at the site consisted of medium to olive-brown,very
moist to wet, medium stiff,clayey,sandy silt(ML).Following the excavation of the test hole,a 6-inch
diameter PVC pipe was inserted into the test hole to a depth of about four(4)feet. Water was then
placed into the plastic pipe and the clayey,sandy silt subgrade soils were presoaked and allowed to
saturate over time. Following the required saturation period,the plastic pipe was again filled with
water and the rate at which the water level dropped was monitored and recorded.The test was
repeated until consistent infiltration test results were obtained.
The results of the field infiltration testing at the site (see Field Infiltration Test Results, Figure No.A-
11)revealed that the ultimate soil infiltration rate of the underlying clayey, sandy silt subgrade soil
was approximately 0.6 inches per hour(in/hr).
LABORATORY TESTING
Representative samples of the on-site subsurface soils were collected at selected depths and
intervals from various test pit explorations and returned to our laboratory for further examination
and testing and/or to aid in the classification of the subsurface soils as well as to help evaluate and
identify their engineering strength and compressibility characteristics.The laboratory testing
consisted of visual and textural sample inspection, moisture content and dry density
determinations, maximum dry density and optimum moisture content,Atterberg Limits and
gradation analyses as well as direct shear strength and "R"-value tests. Results of the various
laboratory tests are presented in the Appendix, Figure No's.A-6 through A-10.
SEISMICITY AND EARTHQUAKE SOURCES
The seismicity of the southwest Washington and northwest Oregon area, and hence the potential
for ground shaking, is controlled by three separate fault mechanisms.These include the Cascadia
Subduction Zone (CSZ),the mid-depth intraplate zone,and the relatively shallow crustal zone.
Descriptions of these potential earthquake sources are presented below.
The CSZ is located offshore and extends from northern California to British Columbia.Within this
zone,the oceanic Juan de Fuca Plate is being subducted beneath the continental North American
Plate to the east.The interface between these two plates is located at a depth of approximately 15
to 20 kilometers(km).
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The seismicity of the CSZ is subject to several uncertainties, including the maximum earthquake
magnitude and the recurrence intervals associated with various magnitude earthquakes.Anecdotal
evidence of previous CSZ earthquakes has been observed within coastal marshes along the
Washington and Oregon coastlines.Sequences of interlayered peat and sands have been
interpreted to be the result of large Subduction zone earthquakes occurring at intervals on the order
of 300 to 500 years,with the most recent event taking place approximately 300 years ago.A recent
study by Geomatrix(1995)suggests that the maximum earthquake associated with the CSZ is
moment magnitude (Mw)8 to 9.This is based on an empirical expression relating moment
magnitude to the area of fault rupture derived from earthquakes that have occurred within
Subduction zones in other parts of the world.An Mw 9 earthquake would involve a rupture of the
entire CSZ.As discussed by Geomatrix(1995)this has not occurred in other subduction zones that
have exhibited much higher levels of historical seismicity than the CSZ,and is considered unlikely.
For the purpose of this study an earthquake of Mw 8.5 was assumed to occur within the CSZ.
The intraplate zone encompasses the portion of the subducting Juan de Fuca Plate located at a
depth of approximately 30 to 50 km below western Washington and western Oregon.Very low
levels of seismicity have been observed within the intraplate zone in western Oregon and western
Washington. However,much higher levels of seismicity within this zone have been recorded in
Washington and California.Several reasons for this seismic quiescence were suggested in the
Geomatrix(1995)study and include changes in the direction of Subduction between Oregon,
Washington,and British Columbia as well as the effects of volcanic activity along the Cascade Range.
Historical activity associated with the intraplate zone includes the 1949 Olympia magnitude 7.1 and
the 1965 Puget Sound magnitude 6.5 earthquakes. Based on the data presented within the
Geomatrix(1995) report, an earthquake of magnitude 7.25 has been chosen to represent the
seismic potential of the intraplate zone.
The third source of seismicity that can result in ground shaking within the northwest Oregon and
southwest Washington area is near-surface crustal earthquakes occurring within the North
American Plate.The historical seismicity of crustal earthquakes in this area is higher than the
seismicity associated with the CSZ and the intraplate zone.The 1993 Scotts Mills(magnitude 5.6)
and Klamath Falls(magnitude 6.0),Oregon earthquakes were crustal earthquakes.
Liquefaction
Seismic induced soil liquefaction is a phenomenon in which loose,granular soils and some silty soils,
located below the water table,develop high pore water pressures and lose strength due to ground
vibrations induced by earthquakes. Soil liquefaction can result in lateral flow of material into river
channels,ground settlements and increased lateral and uplift pressures on underground structures.
Buildings supported on soils that have liquefied often settle and tilt and may displace laterally.Soils
located above the ground water table cannot liquefy, but granular soils located above the water
table may settle during the earthquake shaking.
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Our review of the subsurface soil test hole logs from our exploratory field explorations(TP-#1
through TP-#3) and laboratory test results indicates that the site is generally underlain by medium
stiff to stiff,clayey,sandy silt to depths of at least 6 feet beneath existing site grades. Additionally,
groundwater and/or groundwater seepage was not encountered at the site during our field
exploration work. In this regard,due to the cohesive and medium stiff to stiff nature of the clayey,
sandy silt subgrade soil deposits beneath the site, it is our opinion that the native clayey,sandy silt
subgrade soil deposits located beneath the site do not have the potential for liquefaction during the
design earthquake motions previously described.
Landslides
No ancient and/or active landslides were observed or are known to be present on the subject site.
Additionally,due to the relatively flat-lying to gently sloping nature of the subject site,the risk of
seismic induced slope instability at the site resulting in landslides and/or lateral earth movements
do not appear to present a serious potential geologic hazard.
Surface Rupture
Although the site is generally located within a region of the country known for seismic activity, no
known faults exist on and/or beneath the subject site. However,the Safari Fault is believed to be
located immediately adjacent to and/or to the south of the subject site.As such,the risk of surface
rupture due to faulting should be considered.
Tsunami and Seiche
A tsunami,or seismic sea wave,is produced when a major fault under the ocean floor moves
vertically and shifts the water column above it.A seiche is a periodic oscillation of a body of water
resulting in changing water levels,sometimes caused by an earthquake.A tsunami and seiche
should be considered a potential hazard at this site because the site is located near to the coast
and/or a significant body of water.
Flooding and Erosion
Stream flooding is a potential hazard that should be considered in lowland areas of Washington
County and Tigard.The FEMA(Federal Emergency Management Agency)flood maps should be
reviewed as part of the design for the proposed new Taco Bell structure and its associated site
improvements. Elevations of structures on the site should be designed based upon consultants
reports, FEMA(Federal Emergency Management Agency),and Washington County requirements for
the 100-year flood levels of any nearby creeks and/or streams.
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CONCLUSIONS AND RECOMMENDATIONS
General
Based on the results of our field explorations, laboratory testing,and engineering analyses, it is our
opinion that the site is generally suitable for the proposed new Taco Bell restaurant development
and its associated site improvements provided that the recommendations contained within this
report are properly incorporated into the design and construction of the project.
The primary features of concern at the site are 1)the presence of the existing site and/or surface
improvements across the site and 2)the moisture sensitivity of the near surface clayey,sandy silt
subgrade soils.
With regard to the presence of the existing site and/or surface improvements,we recommend that
all old and/or abandoned foundations and utility services be removed in their entirety down to firm
and suitable native subgrade soil approved by the Geotechnical Engineer. In regards to the moisture
sensitivity of the near surface clayey,sandy silt subgrade soils,we recommend that all site grading
and earthwork operations be scheduled (if possible)for the drier summer months which is typically
June through September.
The following sections of this report provide specific recommendations regarding subgrade
preparation and grading as well as foundation and floor slab design and construction for the new
Taco Bell development project.
Site Preparation
As an initial step in site preparation,we recommend that the proposed new Taco Bell building area
and its associated structural and/or site improvement area(s) be stripped and cleared of all existing
improvements,any existing undocumented fill materials,surface debris,existing vegetation,topsoil
materials,and/or any other deleterious materials present at the time of construction. In general,we
envision that the site stripping and clearing to remove existing site and/or surface improvements
will generally be about 6 to 12 inches. However, localized areas requiring deeper removals,such as
old and/or abandoned foundation remnants and/or utility services,will be encountered and should
be evaluated at the time of construction by the Geotechnical Engineer.The stripped and cleared
materials should be properly disposed of as they are generally considered unsuitable for use/reuse
as fill materials.
Following the completion of the site stripping and clearing work and prior to the placement of any
required structural fill materials and/or structural improvements,the exposed subgrade soils within
the planned structural improvement area(s)should be inspected and approved by the Geotechnical
Engineer and possibly proof-rolled with a half and/or fully loaded dump truck.Areas found to be soft
or otherwise unsuitable should be over-excavated and removed or scarified and recompacted as
structural fill. During wet and/or inclement weather conditions, proof rolling and/or scarification
and recompaction as noted above may not be appropriate.
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The on-site native silty sand subgrade soil materials are considered suitable for use/reuse as
structural fill materials provided they are free of organic materials,debris,and rock fragments in
excess of about 6 inches in dimension. If site grading is performed during wet or inclement weather
conditions,the use of the existing on-site silty sand subgrade soil materials may be difficult. In this
regard,during wet or inclement weather conditions,we.recommend that an import structural fill
material be utilized which should consist of a free-draining(clean)granular fill (sand &gravel)
containing no more than about 5 percent fines. Representative samples of the materials which are
to be used as structural fill materials should be submitted to the Geotechnical Engineer and/or
laboratory for approval and determination of the maximum dry density and optimum moisture
content for compaction.
In general, all site earthwork and grading activities should be scheduled for the drier summer
months(June through September)if possible. However, if wet weather site preparation and grading
is required, it is generally recommended that the stripping of topsoil materials and/or surface
vegetation be accomplished with a tracked excavator utilizing a large smooth-toothed bucket
working from areas yet to be excavated. In this regard,we recommend that areas in which
construction equipment will be traveling be protected by covering the exposed subgrade soils with a
woven geotextile fabric such as Mirafi FW404 followed by at least 12 inches or more of crushed
aggregate base rock. Further,the geotextile fabric should have a minimum Mullen burst strength of
at least 250 pounds per square inch for puncture resistance and an apparent opening size (AOS)
between the U.S.Standard No.70 and No. 100 sieves.
All structural fill materials placed within the new building and/or pavement areas should be
moistened or dried as necessary to near(within 3 percent)optimum moisture conditions and
compacted by mechanical means to a minimum of 92 percent of the maximum dry density as
determined by the ASTM D-1557(AASHTO T-180)test procedures.Structural fill materials should be
placed in lifts(layers)such that when compacted do not exceed about 8 inches.Additionally,all fill
materials placed within five(5) lineal feet of the perimeter(limits)of the proposed Taco Bell
structure and/or pavements should be considered structural fill.All aspects of the site grading
should be monitored and approved by a representative of Redmond Geotechnical Services, LLC.
Foundation Support
Based on the results of our investigation, it is our opinion that the site of the proposed new Taco
Bell development is suitable for support of the restaurant structure provided that the following
foundation design recommendations are followed.The following sections of this report present
specific foundation design and construction recommendations for the planned new Taco Bell
structure.
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Conventional Shallow Foundations
In general,conventional shallow continuous(strip)footings and individual(spread)column footings
for the proposed Taco Bell structure may be supported by approved native clayey, sandy silt
deposits and/or approved structural fill soil materials based on an allowable contact bearing
pressure of about 2,000 pounds per square foot(psf).This recommended allowable contact bearing
pressure is intended for dead loads and sustained live loads and may be increased by one-third for
the total of all loads including short-term wind or seismic loads.Additionally,the above
recommended allowable contact bearing pressure assumes that the site will be graded and/or filled
in such a way as to provide for a minimum of at least three(3)feet of structural fill beyond the outer
perimeter of the building foundations.
In general,continuous strip footings should have a minimum width of at least 16 inches and be
embedded at least 18 inches below the lowest adjacent finish grade (includes frost protection).
Individual column footings(where required)should be embedded at least 18 inches below grade
and have a minimum width of at least 24 inches.However,we point out that foundation excavations
performed during wet and/or inclement weather conditions may experience some deterioration of
the exposed bearing surfaces.As such,where foundation excavations are performed during periods
of wet and/or inclement weather,we recommend that the exposed foundation bearing surfaces be
covered with a 4-to 6-inch layer of compacted crushed aggregate for protection.
Total and differential settlements of foundations constructed as recommended above and
supported by approved native silty sand and/or by properly compacted structural fill materials are
expected to be well within the tolerable limits for this type of wood-framed structure and should
generally be less than about 1-inch and 1/2-inch, respectively.
Allowable lateral frictional resistance between the base of the footing element and the supporting
subgrade bearing soil can be expressed as the applied vertical load multiplied by a coefficient of
friction of 0.35 and 0.45 for sandy silt structural fill soils and/or for import gravel fill materials,
respectively. In addition,lateral loads may be resisted by passive earth pressures on footings poured
"neat"against in-situ (native)subgrade soils or properly backfilled with structural fill materials based
on an equivalent fluid density of 300 pounds per cubic foot(pcf).This recommended value inclu es
a factor of safety of approximately 1.5 which is appropriate due to the amount of movement
required to develop full passive resistance.
Floor Slab Support
We recommend that the concrete floor slab be underlain by a minimum of 4 inches of free-draining
(less than 5 percent passing the No. 200 sieve),well-graded,crushed rock.The crushed rock should
help provide a capillary break to prevent migration of moisture through the slab.Additional
moisture protection,where needed,can be provided by using a vapor retarding membrane and/or
10-mil polyolefin geo-membrane sheet such as StegoWrap. However,the use of a visqueen vapor
barrier covered with a protective layer of sand during wet and/or inclement weather conditions may
not be appropriate.
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The base course materials should be compacted to at least 95 percent of the maximum dry density
as determined by the ASTM D-1557 (AASHTO T-180)test procedures.Where floor slab subgrade
materials are undisturbed,firm and stable and where the underslab aggregate base rock section has
been prepared and compacted as recommended above,we recommend that a modulus of subgrade
reaction of 250 pci be used for design.
Retaining/Below Grade Walls
Retaining and/or below grade walls should be designed to resist lateral earth pressures imposed by
native soils or granular backfill materials as well as any adjacent surcharge loads. For walls which are
unrestrained at the top and free to rotate about their base,we recommend that active earth
pressures be computed on the basis of the following equivalent fluid densities:
Non-Restrained Retaining Wall Pressure Design Recommendations
Slope Backfill Equivalent Fluid Density/Silt Equivalent Fluid
(Horizontal/Vertical) (pcf) Density/Gravel(pcf)
Level 35 30
3H:1V 60 50
2H:1V 90 80
For walls which are fully restrained at the top and prevented from rotation about their base,we
recommend that at-rest earth pressures be computed on the basis of the following equivalent fluid
densities:
Restrained Retaining Wall Pressure Design Recommendations
Slope Backfill Equivalent Fluid Density/Silt Equivalent Fluid
(Horizontal/Vertical) (pcf) Density/Gravel (pcf)
Level 45 35
3H:1V 65 60
2H:1V 95 90
The above recommended values assume that the walls will be adequately drained to prevent the
buildup of hydrostatic pressures.Where wall drainage will not be present and/or if adjacent
surcharge loading is present,the above recommended values will be significantly higher.
Backfill materials behind walls should be compacted to 90 percent of the maximum dry density as
determined by the ASTM D-1557(AASHTO T-180)test procedures.Special care should be taken to
avoid over-compaction near the walls which could result in higher lateral earth pressures than those
indicated herein. In areas within three (3)to five(5)feet behind walls,we recommend the use of
hand-operated compaction equipment.
REDMOND GEOTECHNICAL SERVICES
Project No. 1141.010.G
Page No. 12
Pavements
Flexible pavement design for this project was determined on the basis of projected traffic volume
and loading conditions relative to one (1) laboratory subgrade soil strength characteristic of the
existing clayey silt fill soil materials. Based on a subgrade "R"-value of 32(Resilient Modulus=5,000
to 10,000)and utilizing the American Association of State Highway and Transportation Officials
(AASHTO) 1993"Design of Pavement Structures" manual, we have developed the following flexible
pavement section(s)for the access drives and automobile parking areas:
Asphaltic Concrete Crushed Base Rock
Thickness(inches) Thickness(inches)
Automobile Parking/Drive Areas 3.0 8.0
Note:The above minimum recommended asphalt concrete pavement section(s)assumes a
reliability factor of 75 percent and a subgrade soil classification of fair(MR=5,000 to
10,000).As such,the above recommended flexible pavement section(s)assume that the
subgrade soils will consist of approved(recompacted)silty sand fill soils. However,
where wet weather construction is anticipated and/or required,the use of an additional 4
inches of aggregate base rock and/or the use of a geotextile fabric may also be required.
Additionally,the above recommended flexible pavement section(s)assumes a design life
of approximately 20 years.
Pavement Subgrade,Base Course&Asphalt Materials
The above recommended pavement section(s)were based on the design assumptions listed herein
and on the assumption that construction of the road and/or pavement section(s)will be completed
during an extended period of reasonably dry weather.All thicknesses given are intended to be the
minimum acceptable. Increased base rock sections and the use of geotextile fabric may be required
during wet and/or inclement weather conditions and/or in order to adequately support construction
traffic and protect the subgrade during construction.Additionally,the above recommended
pavement section(s)assume that the subgrade will be prepared as recommended herein,that the
exposed subgrade soils will be properly protected from rain and construction traffic,and that the
subgrade is firm and unyielding at the time of paving. Further, it assumes that the subgrade is
graded to prevent any ponding of water which may tend to accumulate in the base course.
Pavement base course materials should consist of well-graded 1-1/2 inch and/or 3/4-inch minus
crushed base rock having less than 5 percent fine materials passing the No.200 sieve.The base
course and asphaltic concrete materials should conform to the requirements set forth in the latest
edition of the Oregon Department of Transportation,Standard Specifications for Highway
Construction.The base course materials should be compacted to at least 95 percent of the
maximum dry density as determined by the ASTM D-1557(AASHTO T-180)test procedures.The
asphaltic concrete paving materials should be compacted to at least 92 percent of the theoretical
maximum density as determined by the ASTM D-2041(Rice Gravity)test method.
REDMOND GEOTECHNICAL SERVICES
•
1
Project No. 1141.010.G
Page No. 13
Excavations/Slopes
Temporary excavations of up to about four(4)feet in depth may be constructed with near vertical
inclinations.Temporary excavations greater than about four(4)feet but less than eight (8)feet
should be excavated with inclinations of at least 1 to 1 (horizontal to vertical) or properly
braced/shored.Where excavations are planned to exceed about eight(8)feet,this office should be
consulted.All shoring systems and/or temporary excavation bracing for the project should be the
responsibility of the excavation contractor.
Surface Drainage/Groundwater
We recommend that positive measures be taken to properly finish grade the site so that drainage
waters from building and landscaping areas as well as adjacent properties or buildings are directed
away from the new restaurant structure foundations and/or floor slabs.All roof drainage should be
directed into conduits that carry runoff water away from the restaurant building to a suitable
outfall. Roof downspouts should not be connected to foundation drains. A minimum ground slope
of about 2 percent is generally recommended in unpaved areas around the building.
Groundwater and/or groundwater seepage was not encountered at the site within any of the
exploratory test pits at the time of excavation. However,groundwater elevations in the area may
fluctuate seasonally and may temporarily pond/perch near the ground surface during periods of
prolonged rainfall. In this regard, based on our current understanding of the project,we are
generally of the opinion that the anticipated static groundwater levels beneath the site are below
the existing site grades.As such, based on our current understand of the site grading required to
bring the subject site to finish design grades,we are of the opinion that an underslab drainage
system is not required for the proposed Taco Bell structure. However,a foundation drain is
recommended for any perimeter foundations as well as any below grade and/or retaining walls.A
typical perimeter footing and/or retaining wall drain detail is shown on Figure No. 3.
Design Infiltration Rates
Based on the results of our field infiltration testing,we recommend using the following infiltration
rates to design the storm water infiltration and/or disposal systems for the project:
Subgrade Soil Type Recommended Infiltration Rate
clayey,sandy SILT(ML) 0.3 inches per hour(in/hr)
Note:A safety factor of two(2)was used to calculate the above recommended design
infiltration rate(s).Additionally,given the gradational variability of the on-site clayey,
sandy silt subgrade soils beneath the site, it is generally recommended that field testing
be performed during and/or following construction of the on-site storm water infiltration
system in order to confirm that the above recommended design infiltration rates are
appropriate.
REDMOND GEOTECHNICAL SERVICES
• Asphalt or landscaping soil as required
(slope surface to drain)—see Note 3
iYN�
6"seal of compacted native soil
2 (tandsca.:. areas only)
4 General Backfill
1 Undersiab drain .
5'from wall line '('''•:;.12"min •
t Chimney Drainage Zone
... ,...;?....i..,...,....... :::::::::..*::::':..:.:•..i.:;:."::::':.::::.:. ft. 12"minimum cover over pipe,
'.::' 6"minimum cover over footing
,00• O :00 00 .0,,.1 • A:.'
c::1(, •,?: o , vr,,v^�-0G vo 4
o' '�ir.�GUn a � . Filter Fabric
Drain Gravel
• Preferred Perforated
s . Drain Pipe Location
(-
2
SCHEMATIC-NOT TO SCALE
NOTES:
1. Filter Fabric to be non-woven geotextile (Amoco 4545,Mirafi 140N,or equivalent)
2. Lay perforated drain pipe on minimum 0.5%gradient,widening excavation as required.
Maintain pipe above 2:1 slope,as shown.
3. All-granular backfill is recommended for support of slabs,pavements,etc.(see text for
structural f►lf)•
4. Drain gravel to be clean,washed %"to 1W gravel.
5. General backfill to be on-site gravels,or'/.""-0 or 1W-0 crushed rock compacted to 92%
Modified Proctor(AASHTO T-160).
6. Chimney drainage zone to be 12'wide(minimum)zone of clean washed,medium to coarse
sand or drain gravel if protected with filter fabric. Alternatively,prefabricated drainage structures
(Miradrain 6000 or similar)may be used.
PEREIMETER FOOTING/RETAINING WALL DETAIL
Project No. 1141.O10.G TIGARD TACO BELL SITE Figure No. 3
Project No. 1141.010.G
Page No. 14
Seismic Design Considerations
Structures at the site should be designed to resist earthquake loading in accordance with the
methodology described in the 2014 and/or latest edition of the State of Oregon Structural Specialty
Code(OSSC)and/or Amendments to the 2015 International Building Code(IBC).The maximum
considered earthquake ground motion for short period and 1.0 period spectral response may be
determined from the Washington Structural Specialty Code and/or Figures 1613(1)and 1613(2)of
the 2009 National Earthquake Hazard Reduction Program (NEHRP)"Recommended Provisions for
Seismic Regulations for New Buildings and Other Structures" published by the Building Seismic
Safety Council.We recommend Site Class"D" be used for design per Table 1613.5.2.
Using this information,the structural engineer can select the appropriate site coefficient values(Fa
and Fv)from Tables 1613.5.3 (1)and 1613.5.3(2)of the 2015 IBC to determine the maximum
considered earthquake spectral response acceleration for the project. However,we have assumed
the following response spectrum for the project:
Table 1.IBC Seismic Design Parameters
Site
Class Ss Si Fa Fv SMS SM. SOS Sol
D 0.965 0.421 1.114 1.579 1.075 0.665 0.716 0.443
Notes: 1.Ss and Si were established based on the USGS 2015 mapped maximum considered
earthquake spectral acceleration maps for 2%probability of exceedence in 50 years.
2. Fa and Fv were established based on IBC 2015 tables 1613.5.3 (1)and 1613.5.3 (2) using
the selected Ss and Si values.
EROSION CONTROL
During our field exploration program,we did not observe soil types that would generally be
considered highly susceptible to erosion. In our opinion,the primary concern regarding erosion
potential will occur during construction, in areas that have recently been stripped and/or cleared of
surface vegetation. Erosion at the site during construction can be minimized by implementing a
project erosion control plan which should include the judicious use of straw bales and silt fences. If
used,these erosion control devices should be in place and remain in place throughout all of the site
grading and construction operations. Erosion and sedimentation of exposed subgrade soils can also
be minimized by quickly re-vegetating exposed areas of soil and by staging construction such that
large areas of the subject site are not denuded and exposed at the same time.Areas of exposed soil
requiring immediate and/or temporary protection against exposure should be covered with either
mulch or erosion control netting/blankets.Areas of exposed soil requiring permanent stabilization
measures should be seeded with an approved grass seed mixture or hydroseeded with an approved
seed-mulch-fertilizer mixture.
REDMOND GEOTECHNICAL SERVICES
Project No. 1141.010.G
Page No. 15
CONSTRUCTION MONITORING AND TESTING
We recommend that Redmond Geotechnical Services,LLC be retained to provide construction
monitoring and testing services during all earthwork operations for the proposed new Taco Bell
development.The purpose of our monitoring services would be to confirm that the site conditions
reported herein are as anticipated,provide field recommendations as required based on the actual
conditions encountered,document the activities of the grading contractor and assess his/her
compliance with the project specifications and recommendations. It is important that our
representative meet with the contractor prior to grading to help establish a plan that will minimize
costly over-excavation and site preparation work.Of primary importance will be observations made
during site preparation,structural fill placement,footing excavations and construction as well as
retaining wall backfill.
CLOSURE AND LIMITATIONS
This report is intended for the exclusive use of the addressee and/or their representative(s)to use
to design and construct the proposed new Taco Bell structure and its associated site improvements
described herein as well as to prepare any related construction documents.The conclusions and
recommendations contained in this report are based on site conditions as they presently exist and
assume that the explorations are representative of the subsurface conditions between the
explorations and/or across the study area.The data, analyses,and recommendations herein may
not be appropriate for other structures and/or purposes.We recommend that parties
contemplating other structures and/or purposes contact our office. In the absence of our written
approval,we make no representation and assume no responsibility to other parties regarding this
report.Additionally, Redmond Geotechnical Services, LLC assumes no responsibility and/or liability
for any engineering judgment,inspections,and/or testing services performed by others or for
problems which may arise due to the lack of understanding and/or inspection during construction.
It is the owners/developers responsibility for insuring that the project designers and/or contractors
involved with this project implement our recommendations into the final design plans,specifications
and/or construction activities for the project. Further,in order to avoid delays during construction,
we recommend that the final design plans and specifications for the project be reviewed by our
office to evaluate as to whether our recommendations have been properly interpreted and
incorporated into the project.
If during any future site grading and construction,subsurface conditions different from those
encountered in the explorations are observed or appear to be present beneath excavations,we
should be advised immediately so that we may review these conditions and evaluate whether
modifications of the design criteria are required.We also should be advised if significant
modifications of the proposed site development are anticipated so that we may review our
conclusions and recommendations.
REDMOND GEOTECHNICAL SERVICES
Project No. 1141.010.G
Page No. 16
LEVEL OF CARE
The services performed by the Geotechnical Engineer for this project have been conducted with that
level of care and skill ordinarily exercised by members of the profession currently practicing in the
area under similar budget and time restraints. No warranty or other conditions,either expressed or
implied, is made.
REDMOND GEOTECHNICAL SERVICES
Project No. 1141.010.G
Page No. 17
REFERENCES
•
Adams,John, 1984,Active Deformation of the Pacific Northwest Continental Margin:Tectonics,v.3,
No.4, p.449-472.
Applied Technology Council,ATC-13, 1985, Earthquake Damage Evaluation Data for California.
Atwater, B.F., 1992,Geologic evidence for earthquakes during the past 2000 years along the Copalis
River,southern coastal Washington:Journal of Geophysical Research,v.97, p. 1901-1919.
Atwater, B.F., 1987a,A periodic Holocene recurrence of widespread, probably coseismic Subsidence
in southwestern Washington: EOS,v.68, no.44.
Atwater, B.F., 1987b, Evidence for great Holocene earthquakes along the outer coast of Washington
State:Science,v. 236, no.4804, pp.942-944.
Campbell, K.W., 1990, Empirical prediction of near-surface soil and soft-rock ground motion for the
Diablo Canyon Power Plant site,San Luis Obispo County,California: Dames& Moore report to
Lawrence Livermore National Laboratory.
Carver,G.A., and Burke, R.M., 1987, Late Holocene paleoseismicity of the southern end of the
Cascadia Subduction zone [abs.]: EOS,v.68, no.44, p. 1240.
Chase, R.L.,Tiffin, D.L.,Murray,J.W., 1975,The western Canadian continental margin: In Yorath, C.J.,
Parker, E.R.,Glass, D.J.,editors,Canada's continental margins and offshore petroleum exploration:
Canadian Society of Petroleum Geologists Memoir 4, p.701-721.
Crouse,C.B., 1991a,Ground motion attenuation equations for earthquakes on the Cascadia
Subduction Zone: Earthquake Spectra,v. 7, no.2, pp.201-236.
Crouse,C.B., 1991b, Errata to Crouse(1991a), Earthquake Spectra,v.7, no. 3,p. 506.
Darienzo,M.E.,and Peterson, C.D., 1987, Episodic tectonic subsidence recorded in late Holocene
salt marshes, northern Oregon central Cascadia margin:Tectonics,v.9, p. 1-22.
Darienzo, M.E.,and Peterson,C.D., 1987, Episodic tectonic subsidence recorded in late Holocene
salt marshes northwest Oregon [abs]: EOS,v. 68, no.44, p. 1469.
EERI (Earthquake Engineering Research Institute), 1993,The March 25, 1993, Scotts Mill Earthquake,
Western Oregon's Wake-Up Call: EERI Newsletter,Vol. 27, No.5, May.
Geologic Map and Database (Open File Report 00-367)of the Roseburg Quadrangle, Douglas and
Coos Counties,Oregon dated 2000.
REDMOND GEOTECHNICAL SERVICES
Project No. 1141.010.G
Page No. 18
Geomatrix, 1995 Seismic Design Mapping,State of Oregon: Final Report to Oregon Department of
Transportation,January.
Geologic Map Series(GMS-49), Map of Oregon Seismicity, 1841-1986 dated 1986.
Geologic Map Series(GMS-97), Geologic Map of the Beaverton Quadrangle,Washington County,
Oregon dated 1995.
Grant, W.C.,and McLaren,D.D., 1987, Evidence for Holocene Subduction earthquakes along the
northern Oregon coast [abs]: EOS v.68,no.44,p. 1239.
Grant,W.C.,Atwater, B.F.,Carver,G.A., Darienzo, M.E., Nelson,A.R., Peterson,C.D., and Vick,G.S.,
1989, Radiocarbon dating of late Holocene coastal subsidence above the Cascadia Subduction zone-
compilation for Washington,Oregon,and northern California, [abs]: EOS Transactions of the
American Geophysical Union,v.70, p. 1331.
International Conference of Building Officials (ICBO), 1994, Uniform Building Code: 1994 Edition,
Whittier,CA. 1994.
Joyner,W.B.,and Boore, D.M., 1998, Measurement,characterization and prediction of strong
ground motion: Earthquake Engineering and Soil Dynamics II—Recent Advances in Ground Motion
Evaluation,ASCE Geotech.Special Publ. No. 20, p.43-102.
Riddihough, R.P., 1984, Recent movements of the Juan de Fuca plate system:Journal of Geophysical
Research,v.89, no. 88, p.6980-6994.
Youngs, R.R., Day,S.M.,and Stevens,J.L., 1998, Near field ground motions on rock for large
Subduction earthquakes: Earthquake Engineering and Soil Dynamics II—Recent Advances in Ground
Motion Evaluation,ASCE Geotech.Special Publ. No. 20, p.445-462.
REDMOND GEOTECHNICAL SERVICES
Appendix A
Test Pit Logs and Laboratory Test Results
APPENDIX
FIELD EXPLORATIONS AND LABORATORY TESTING
•
FIELD EXPLORATION
Subsurface conditions at the site were explored by advancing three(3)exploratory test pits on June
14,2018.The approximate location of the test pit explorations are shown in relation to the existing
site features and/or the proposed new Taco Bell structure on the Site Exploration Plan, Figure No. 2.
The test holes were advanced using portable excavation equipment in general conformance with
ASTM Methods in Vol.4.08, D-1586-94 and D-1587-83.The test holes were advanced to depths of
about six(6)feet beneath existing site grades. Detailed logs of the exploratory test holes are
presented on the Log of Test Pits, Figure No's. A-4 and A-5.The soils were classified in accordance
with the Unified Soil Classification System(USCS),which is outlined on Figure No.A-3.
The exploration program was coordinated by a field engineer who monitored the exploration
activity,obtained representative samples of the subsurface soils encountered,classified the soils by
visual and textural examination, and maintained continuous logs of the subsurface conditions.
Disturbed and/or undisturbed samples of the subsurface soils were obtained at appropriate depths
and/or intervals and placed in plastic bags and/or with a thin walled ring sample.
Groundwater and/or groundwater seepage was not encountered within any of the exploratory test
holes at the time of excavation to depth of at least 6.0 feet beneath existing site grades.
LABORATORY TESTING
Pertinent physical and engineering characteristics of the soils encountered during our subsurface
investigation were evaluated by a laboratory testing program to be used as a basis for selection of
soil design parameters and for correlation purposes.Selected tests were conducted on
representative soil samples.The program consisted of tests to evaluate the existing(in-situ)
moisture-density, maximum dry density and optimum moisture content,Atterberg Limits and
gradational characteristics as well as direct shear strength and "R"-value testing.
Dry Density and Moisture Content Determinations
Density and moisture content determinations were performed on both disturbed and relatively
undisturbed samples from the test pit explorations in general conformance with ASTM Vol.4.08 Part
D-216.The results of these tests were used to calculate existing overburden pressures and to
correlate strength and compressibility characteristics of the soils.Test results are shown on the test
pit logs at the appropriate sample depths.
REDMOND GEOTECHNICAL SERVICES
A
A-2
Maximum Dry Density
One(1) Maximum Dry Density and Optimum Moisture Content test was performed on a
representative sample of the existing clayey,sandy silt subgrade soils in accordance with ASTM Vol.
4.08 Part D-1557.This test was conducted to help establish various engineering properties for
use/reuse as structural fill.The test results appear on Figure No.A-6.
Atterberg Limits
Two(2) Liquid Limit(LL)and Plastic Limit(PL)tests were performed on representative samples of
the sandy, clayey silt subgrade soils in accordance with ASTM Vol.4.08 Part D-4318-85.These tests
were conducted to facilitate classification of the soils and for correlation purposes.The test results
appear on Figure No. A-7.
Gradation Analysis
Gradation analyses were performed on representative samples of the clayey,sandy silt subgrade
soils in accordance with ASTM Vol.4.08 Part D-422.The test results were used to classify the soil in
accordance with the Unified Soil Classification System (USCS).The test results are shown graphically
on Figure No.A-8.
Direct Shear Strength Test
One(1) Direct Shear Strength test was performed on an undisturbed and/or remolded sample of the
native clayey,sandy silt subgrade soils at a continuous rate of shearing deflection(0.02 inches per
minute) in accordance with ASTM Vol.4.08 Part D-3080-79.The test results were used to determine
engineering strength properties and are shown graphically on Figure No.A-9.
"R"-Value Test
One(1) "R"-value test was performed on a representative sample of the existing clayey,sandy silt
subarade soils in general conformance with ASTM Vol.4.08 Part D-2844.The test results were used
to help evaluate the subgrade soils supporting and performance capabilities when re-compacted
and subjected to vehicle and/or traffic loading.The test results are shown on Figure No.A-10.
The following figures are attached and complete the Appendix:
Figure No.A-3 Key To Exploratory Test Pit Logs
Figure No's.A-4 and A-5 Log of Test Pits
Figure No.A-6 Maximum Density/Expansion Index Test Results
Figure No.A-7 Plasticity Chart and Data
Figure No.A-8 Gradation Test Results
Figure No.A-9 Direct Shear Strength Test Results
Figure No.A-10 "R"-Value Test Results
Figure No.A-11 Field Infiltration Test Results
REDMOND GEOTECHNICAL SERVICES
PRIMARY DIVISIONS GROUP
SYMBOL SECONDARY DIVISIONS
' t
GRAVELS CLEAN GW Well graded gravels, gravel-sand mixtures, little or no
Q GRAVELS fines.
J
CE 0 MORE THAN HALF (LESS 7HAN Poorly graded gravels or gravel-sand mixtures, little or
p d OF COARSE 5% FINES) G P no fines.
Cr) 2 p FRACTION IS
z GRAVEL GM Silty gravels, gravel-sand-silt mixtures, non-plastic fines.
u
LARGER THAN WITH
Z 0 r in NO. 4 SIEVE FINES GC Clayey gravels, gravel-sand-clay mixtures, plastic fines.
. CLEAN
Q ~ _ SANDS
cc u' SANDS SW Well graded sands, gravelly sands, little or no fines.
W < LD ORE THAN HALF (LESS THAN
cc E J5% FINES)
OF COARSES P Poorly graded sands or gravelly sands, little or no fines.
0 W FRACTION IS
0O SANDSu) SM Silty sands,sand-silt mixtures, non-plastic fines.
0 SMALLER THAN WITH
NO. 4 SIEVE FINES SC Clayey sands, sand-clay mixtures, plastic fines.
N ML Inorganic silts and very fine sands, rock flour, silty or
J LL SILTS AND CLAYS clayey fine sands or clayey.silts with slight plasticity.
_ Q w to
O
t/p ua LIQUID LIMIT IS C L Inorganic clays of low to medium plasticity, gravelly
J Q w clays, sandy clays, silty clays, lean clays.
'Q LESS THAN 50%
Z_ z N O OL Organic silts and organic silty clays of low plasticity.
-' o SILTS AND CLAYS MH Inorganic silts,micaceous or diatomaceous fine sandy or
►- d silty soils, elastic silts.
C 2
w 0 Z LIQUID LIMIT IS CH Inorganic clays of high plasticity, fat clays.
Z Q
it 2 2 1 GREATER THAN 50%
OH Organic clays of medium to high plasticity,organic silts.
HIGHLY ORGANIC SOILS Pt Peat and other highly organic soils.
DEFINITION OF TERMS
U.S. STANDARD SERIES SIEVE CLEAR SQUARE SIEVE OPENINGS
200 40 10 4 3/4" 3" 12"
SAND GRAVEL
SILTS AND CLAYS -- COBBLES BOULDERS
FINE MEDIUM COARSE FINE COARSE
GRAIN SIZES
NOSAN-PLASTIC S AND BLOWS/FOOTf CLAYS AND STRENGTH$ (BLOWS/FOOTf
NON-PLASTIC SILTS PLASTIC SILTS
VERY LOOSE 0 - 4 VERY SOFT 0 - 1/4 0 - 2
LOOSE 4 -10 SOFT 1/4 - 1/2 2 - 4
FIRM 1/2 - 1 4 - 8
MEDIUM DENSE 10 -30 STIFF 1 - 2 g _ 16
DENSE 30 - 50 VERY STIFF 2 - 4 16 - 32
VERY DENSE OVER 50 HARD OVER 4 OVER 32
RELATIVE DENSITY CONSISTENCY
#Number of blows of 140 pound hammer falling 30 inches to drive a 2 inch 0.D.(1-3/8 inch I.D.)
split spoon CASTM D-1586).
#Unconfined compressive strength in tons/sq.ft.as determined by laboratory testing or approximated
by the standard penetration test CASTM 0-1586), pocket penetrometer, torvane, or visual observation.
KEY TO EXPLORATORY TEST PIT LOGS
Unified Soil Classification System (ASTM D-2487)
.r REDMOND
EOiECHNICAL TIGARD TACO BELL SITE
T
, 'I Tigard, Oregon
SERVICES
PO Box 20547 • PORTLAND, OREGON 97294 PROJECT NO. DATE
Figure A-3
1141 .010.G 6/29/18
• . t
BACKHOE COMPANY: Redmond Geotechnical BUCKET SIZE: 3 inches DATE:6/1 4/1 8 r
w } wZ L.
WW m2 zW oz to
ON SOIL DESCRIPTION
J
a1!- H 0~ 0 00
2 c.) Cl,-.- TEST PIT NO. TH-#1 ELEVATION 225 ' ±
—o
ML Dark brown, very moist to wet, soft,
organic, clayey, sandy SILT (Topsoil)
- X 27.7
ML Medium to olive-brown, very moist to wet,
- soft to medium stiff, clayey, sandy SILT '
5— X 28. 1I
Becomes medium stiff to stiff at 5 feet
Total Depth = 6.0 feet
- No groundwater encountered at time of '
exploration '
-
10— I
I
—
—
—
15
TEST PIT NO. TH-#2 ELEVATION 227 ' ±
0
ML Dark brown, very moist to wet, soft,
_ �*, organic, clayey, sandy SILT (Topsoil)
ML Medium to olive-brown, very moist to wet,
soft to medium stiff, clayey, sandy SILT
5-- Becomes medium stiff to stiff at 5 feet
Total Depth = 6.0 feet
_ - .. • . . _ - -encountered at-time--of
_ exploration
10--- ■
15
LOG OF TEST PITS
PROJECT NO. 1141 .010 .G TIGARD TACO BELL SITE FIGURE NO. A-4
REDMOND GEOTECHNICAL SERVICES
I . A
•
BACKHOE COMPANY: Redmond Geotechnical BUCKET SIZE: 3 inches DATE: 6/1 4/1 8
w sit
0.w m2 zcc
c01 y1-7 vv SOIL DESCRIPTION
Q Ili�' OW ozO-
O yce- TEST PIT NO, TH-##3 ELEVATION 229 ±
—o
-
_ML Dark brown, very moist to wet, soft,
organic, clayey, sandy SILT (Topsoil )
- X 27.2 ML Medium to olive-brown, very moist to wet,
soft to medium stiff, clayey, sandy SILT
5- Becomes medium stiff to stiff at 4 feet
Total Depth = 6 . 0 feet
No groundwater encountered at time of
exploration
10—
15
TEST PIT NO. ELEVATION
0 -
5-
10-
15
LOGI OF TEST PITS
PROJECT NO. 1141 .010 .G _ TIGARD TACO BELL SITE 1FIGURENO. A-5
REDMOND GEOTECHNICAL SERVICES
.771
MAXIMUM DENSITY TEST RESULTS
MAXIMUM OPTIMUM
SAMPLE SOIL DESCRIPTION DRY DENSITY MOISTURE
LOCATION (pcf) CONTENT(%)
TH-#1 Medium to olive-brown, clayey, sandy 110.0 18.0
SILT (ML)
2. 0 '
EXPANSION INDEX TEST RESULTS
SAMPLE INITIAL COMPACTED FINAL VOLUMETRIC EXPANSION EXPANSIVE
LOCATION MOISTURE (%) DRY DENSITY MOISTURE (%) SWELL(%) INDEX CLASS.
(pcf)
MAXIMUM DENSITY&EXPANSION INDEX TEST RESULTS
iPROJECT NO.: 1141 .010.G1 TIGARD TACO BELL SITE FIGURE NO.: A-6
REDMOND GEOTECHNICAL SERVICES
1
60 -
50
CH \..
4.
40 --
X
O CL
z
30> —
I-
V MH
P.-
0 20 or—
d
a OH
10
4 L �'�,�'„^CL-MIr ML or OL
0 ML
0 10 20 30 40 50 60 70 80 90 100
LIQUID LIMIT C%)
NATURAL PASSING UNIFIED
KEY BORING SAMPLE LIQUID PLASTICITY LIQUIDITY SOIL
SYMBOL NO. DEPTH WATER LIMIT INDEX NO. 200 INDEX CLASSIFICATION
CONTENT SIEVE SYMBOL
(feet) % % % %
F. TH-#1 2.0 27.7 28. 2 4.4 82.3 ML
PLASTICITY CHART AND DATA
REDMONDdi TIGARD TACO BELL SITE
t` c`/ EO"I"ECI•INIG'AI.. Tigard, Oregon
• SERVICES
PROJECT NO. DATE
PO Box 20547 • PORTLAND, OREGON 97294 Figure A-7
_1141 .010.G _ 6129/18
2. 5
2 .0
1 . 5
crE-
cc •
w1 .0
v7
0.5 `
0.0
0.0 0 .5 1 .0 1 . 5 2 .0 2. 5 3 .0
NORMAL PRESSURE (KSF)
SAMPLE DATA TEST DATA
DESCRIPTION: Medium to olive-brown, TEST NUMBER 1 2 3 4
clayey, sandy SILT (ML) NORMAL PRESSURE(KSF) 0.5 1 .5 2.5
SHEAR STRENGTH(KSF) 0.5 1 . 1 1 .6
BORING NO.: TH-#1 INITIAL H2O CONTENT(%) 18.0 18.0 18.0
DEPTH(It.): 2.0 ELEVATION(It): FINAL H2O CONTENT(°;) 18.4 15. 5 11 .2
��s
TEST RESULTS INITIAL DRY DENSITY(PCF) 98.0 98.0 98.0
APPARENT COHESION(C): 250 psf FINAL DRY DENSITY(PCF) 98.7 103.3 107.7
APPARENT ANGLE OF INTERNAL FRICTION(0); 28 O STRAIN RATE: 0. 02 inches per minute
DIRECT SHEAR TEST DATA
REDMOND
ZIP
TIGARD TACO BELL SITE
`, GEOTECHNICAL Tigard, Oregon
SERVICES
PO Box 20547 • PORTLAND. OREGON 97294 PROJECT NO DATE
Figure A-9
1141 .010.G 1 6/29/18
•
Infiltration Test Results
Location:Tigard Taco Bell Date:June 14, 2018 Test Hole:TH-#2
Depth to Bottom of Hole:4.0 feet Hole Diameter:6 inches Test Method: Encased Falling Head
Tester's Name: Daniel M. Redmond, P.E.,G.E.
Tester's Company: Redmond Geotechnical Services, LLC Tester's Contact Number:503-285-0598
Depth (feet) Soil Characteristics
0-0.75 Dark brown Topsoil
0.75-4.0 Medium to olive-brown,clayey,sandy SILT(ML)
Time Interval Measurement Drop in Water Infiltration Rate Remarks
Time (Minutes) (inches) (inches) (inches/hour)
9:00 0 36.00 ---- Filled w/12" water
9:20 20 36.37 0.37 1.10
9:40 20 36.69 0.32 0.95
10:00 20 36.96 0.27 0.80
10:20 20 37.20 0.24 0.70
10:40 20 37.42 0.22 0.65
11:00 20 37.63 0.21 0.62
11:20 20 37.83 0.20 0.60
11:40 20 38.03 0.20 0.60
Infiltration Test Data Table
Figure No.A-11