Report (10) -CU- W U \ So Su a rm, .
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G l 9750 SW Nimbus Avenue
OFFICE COPY
Beaverton,OR 97008-7172
p 503-641-3478 fl 503-644-8034
June 28, 2017 RECEIVED 5970-6 GEOTECHNICAL RPT
Tigard-Tualatin School District MAR 112019
6960 SW Sandburg Street CITY OF TIGARD
Tigard, OR 97223 BUILDING DIVISION
Attention: Debbie Pearson/DAY CPM Services, LLC
SUBJECT: Geotechnical Investigation and Site-Specific Seismic Hazard Evaluation
Twality Middle School
Tigard, Oregon
At your request, GRI completed a geotechnical investigation for the planned improvements at Twality
Middle School in Tigard, Oregon. The Vicinity Map, Figure 1, shows the general location of the site. The
purpose of the investigation was to evaluate subsurface conditions at the site and develop geotechnical
recommendations for use in the design and construction of the proposed improvements. The investigation
included a review of existing geotechnical information for the site and surrounding area, subsurface
explorations, laboratory testing, and engineering analyses. As part of our investigation, GRI completed a
site-specific seismic-hazard evaluation to satisfy the requirements of the 2012 International Building Code
(IBC), which was adopted by the 2014 Oregon Structural Specialty Code (OSSC). This report describes the
work accomplished and provides conclusions and recommendations for use in the design and construction
of the proposed project.
PROJECT DESCRIPTION
We understand a substantial portion of the existing Twality Middle School will be demolished and rebuilt,
with the remaining portions remodeled under the 2016 Tualatin-Tigard School District Bond Program. The
Site Plan, Figure 2, shows the location of the existing school and associated improvements. Based on our
review of conceptual plans, we understand the entire school, except the southernmost portion that houses
the choir and band rooms, electrical and building-support rooms, STEM and engineering-robotics
classrooms, boys' bathroom and locker room, and main gym, will be demolished and rebuilt as part of this
project. The majority of the new school will consist of a single-story, at-grade structure, except for the
northeastern corner, which will be three stories. In general, the new school will be located within the
existing building footprint; however, the new building will extend 100 ft farther north than the existing
building. Although structural loads for the new building are not currently available, we anticipate the
column and wall loads will be on the order of 100 to 300 kips and 3 to 5 kips/ft, respectively.
We anticipate the finished floor elevation for the new school will be consistent with the existing school,
and cuts and fills to establish grade for the new school will be minimal. We understand a new bus loop
will surround the building on the east and north, and a new parking lot will be constructed immediately
west of the new building, adjacent to SW 97th Avenue. Although grading plans are not currently available,
we anticipate a cut on the order of 10 to 15 ft will be required along SW 97th Avenue to establish grade for
the new parking lot. To retain the cut, a permanent earth-support system, such as a soil nail, tied-back, or
mechanically stabilized earth wall, will be required. We anticipate the new bus loop and parking lot will
be paved with asphalt concrete (AC) pavement, and areas subjected to frequent heavy truck traffic, such as
trash-enclosure and service areas, will be paved with Portland cement concrete (PCC) pavement
Providing geotechnical,pavement,and environmental consulting services since 1984
SITE DESCRIPTION
General
The project site is developed with the existing school building, which will be demolished and rebuilt or
remodeled for this project. The existing school building is bordered by a parking lot, tennis courts, and
portable classrooms on the north; a football field and track on the east; residential structures on the south;
and a grass field on the west. The new bus loop will be constructed between the track and school
building, and the new parking lot will be constructed in the grass field immediately west of the school and
east of SW 97th Avenue. The southernmost portion of the existing school discussed above will remain in its
current configuration, and the remaining portions of the school, parking lot, tennis courts, and portable
classrooms will be removed as part of this project. Review of satellite imagery and our observations at the
site indicate the ground surface gently slopes downward from northwest to southeast across the site.
Geology
Published geologic mapping indicates the site is mantled with Missoula flood deposits, locally referred to
in the project area as the Willamette Silt Formation (Madin, 1990). In general, Willamette Silt is composed
of unconsolidated beds and lenses of silt and sand. Stratification within this formation commonly consists
of 4-to 6-in.-thick beds, although in some areas, the silt and sand are massive and the bedding is indistinct
or nonexistent. Based on explorations completed in the project vicinity, the Willamette Silt is underlain by
Columbia River Basalt at depths of about 27.5 to 75 ft.
SUBSURFACE CONDITIONS
General
Subsurface materials and conditions at the site were investigated between May 3 and May 5, 2017, with
three borings, designated B-1 through B-3; one cone penetrometer test (CPT) sounding, designated CPT-1;
and one dilatometer (DMT) sounding, designated DMT-1. The borings were advanced to depths of about
27.8 to 51.5 ft, the CPT probe to a depth of about 26.3 ft, and the DMT sounding to a depth of about 34 ft
below existing site grades. The approximate locations of the explorations completed for this investigation
are shown on Figure 2. Logs of the borings, CPT probe, and DMT sounding are provided on Figures 1A
through 6A. The field and laboratory programs conducted to evaluate the physical engineering properties
of the materials encountered in the explorations are described in Appendix A. The terms and symbols
used to describe the materials encountered in the explorations are defined on Tables 1A through 3A and in
the attached legend.
In addition, GRI is completing a concurrent geotechnical investigation for the Templeton Elementary
School located immediately southeast of Twality Middle School. As part of our Templeton Elementary
School investigation, three borings, designated B-1TE through B-3TE; three CPT probes, designated CPT-
1TE through CPT-3TE; and one DMT sounding, designated DMT-1TE, were completed between May 3 and
May 5, 2017. The borings were advanced to a depth of about 41.5 ft, the CPT probes to depths of about
42.3 to 76.3 ft, and the DMT sounding to a depth of about 40 ft below existing site grades at the
approximate locations shown on Figure 2. Logs of the explorations and results of laboratory testing
completed for the Templeton Elementary School project are included in Appendix B for reference.
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Sampling
Disturbed and undisturbed soil samples were obtained from the borings at 2.5-ft intervals of depth in the
upper 15 ft, 5-ft intervals to a depth of 40 ft, and 10-ft intervals below 40 ft. Disturbed soil samples were
obtained using a 2-in.-outside- diameter (O.D.) standard split-spoon sampler (SPT). Penetration tests were
conducted by driving the samplers into the soil a distance of 18 in. using a 140-lb hammer dropped 30 in.
The number of blows required to drive the SPT sampler the last 12 in. is known as the Standard Penetration
Resistance, or SPT N-value. SPT N-values provide a measure of the relative density of granular soils and
the relative consistency of cohesive soils. Relatively undisturbed soil samples were collected by pushing a
3-in.-O.D. Shelby tube into the undisturbed soil a maximum of 24 in. using the hydraulic ram of the drill
rig. The soil in the Shelby tubes was extruded in our laboratory and Torvane shear strength measurements
were recorded on selected samples.
Soils
For the purpose of discussion, the materials disclosed by our investigation have been grouped into the
following categories based on their physical characteristics and engineering properties:
1. PAVEMENT
2. Sandy SILT to Silty SAND
3. BASALT
The following paragraphs provide a detailed description of the materials encountered in the explorations
and a discussion of the groundwater conditions at the site.
1. PAVEMENT. Explorations B-2, B-3, CPT-1, and DMT-1 were advanced in existing paved areas and
encountered approximately 2 in. of AC pavement at the ground surface. The pavement is underlain
by about 6 to 14 in. of crushed-rock base (CRB) course.
2. Sandy SILT to Silty SAND. Interbedded layers of sandy silt to silty sand were encountered at the
ground surface in exploration B-1 and beneath the pavement in explorations B-2, B-3, CPT-1, and DMT-1.
The interbedded layers of sandy silt to silty sand extend to depths ranging from about 26 ft to the maximum
depth explored of 51.5 ft. The thicknesses of the interbedded layers typically range from about 2 in. to 15
ft; however, a layer of silty sand up to 35 ft thick was encountered in exploration B-3. The soils are
generally brown with varying degrees of rust mottling. In general, the sandy silt contains fine-to medium-
grained sand and up to a trace of clay, and the silty sand is fine to medium grained. However, up to 2.5-ft-
thick layers of clayey silt were encountered d at depths of 25 and 50 ft in borings B-2 and B-3, respectively.
g .p Y
The natural moisture contents of the silt and sand soils range from 24 to 32% and 17 to 33%, respectively.
The relative consistency of the sandy silt is very soft to stiff, based on N-values of 4 to 11 blows/ft, Torvane
shear strength values of 0.35 to 0.55 tsf, CPT tip-resistance values of about 10 to 60 tsf, and DMT
constrained modulus values of about 20 to 350 tsf, and is typically soft to medium stiff to a depth of 5 ft
and medium stiff to stiff below. The relative density of the silty sand is very loose to very dense, based on
N-values of 4 to 17 blows/ft, CPT tip resistance values of about 15 to 75 tsf, and DMT constrained modulus
values of about 125 to 1,500 tsf, and is typically medium dense. It should be noted the borings were
completed using solid-stem auger drilling techniques and SPT N-values tend to be underestimated in sandy
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soils below the groundwater level using this drilling method. Explorations B-3 and DMT-1 were
terminated in the sandy silt to silty sand deposit at depths of about 51.5 and 34.1 ft, respectively.
3. BASALT. Extremely soft (RO) to very soft (R1) basalt of the Columbia River Basalt Group was
encountered beneath interbedded layers of sandy silt to silty sand at depths of about 26 to 40 ft in
explorations B-1, B-2, CPT-1, and DMT-1. The basalt is predominantly decomposed to decomposed. The
joints and fractures displayed some staining and are filled with black secondary mineralization. N-values
of 50 blows for 2.5 to 5 in. of sampler penetration and CPT tip-resistance values of about 240 to 430 tsf
were recorded in the basalt. Explorations B-1, B-2,CPT-1, and DMT-1 were terminated in basalt at depths
of about 26.3 to 40.5 ft.
Groundwater
Our review of U.S. Geological Survey (USGS) groundwater data suggests the regional groundwater level at
the site typically occurs at depth in the highly fractured, hard basalt that underlies the site. However,
groundwater was encountered at depths of 16 to 29 ft below the ground surface in borings B-1 through B-
3. Explorations completed for this project and our experience in the project vicinity indicate perched
groundwater occurs in the silt and sand soils that mantle the site throughout the year. We anticipate the
local perched groundwater level typically occurs at depths of 20 to 25 ft below the ground surface during
the normally dry summer and fall months and may approach the ground surface during the wet winter and
spring months or during periods of heavy or prolonged precipitation.
CONCLUSIONS AND RECOMMENDATIONS
General
Subsurface explorations completed for this investigation indicate the site is mantled with interbedded layers
of medium-stiff sandy silt and medium-dense silty sand. The interbedded layers of sandy silt and silty sand
extend to depths ranging from 26 ft to greater than 51.5 ft and are underlain by basalt. We anticipate the
local perched groundwater level typically occurs at depths of 20 to 25 ft below the ground surface
throughout the year; however, perched groundwater may approach the ground surface during the wet
winter months and following periods of intense or prolonged precipitation.
In our opinion, foundation support for new structural loads can be provided by conventional spread and
wall foundations established in firm, undisturbed, native soil or compacted structural fill. The primary
geotechnical considerations associated with construction of the proposed building and associated
improvements include the presence of fine-grained soils at the ground surface that are extremely sensitive
to moisture content and the potential for shallow, perched groundwater conditions. The following sections
of this report provide our conclusions and recommendations for use in the design and construction of the
project.
Seismic Considerations
General. We understand the project will be designed in accordance with the 2012 IBC with 2014 OSSC
modifications. For seismic design, the 2012 IBC references the American Society of Civil Engineers (ASCE)
document 7-10, titled "Minimum Design Loads for Buildings and Other Structures" (ASCE 7-10). A site-
specific seismic-hazard evaluation was completed for the project in accordance with the 2014 OSSC.
Details of the site-specific seismic-hazard evaluation and the development of the recommended response
spectra are provided in Appendix C.
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Code Background. The 2012 IBC and ASCE 7-10 seismic hazard levels are based on a Risk-Targeted
Maximum Considered Earthquake (MCER) with the intent of including the probability of structural collapse.
The ground motions associated with the probabilistic MCER represent a targeted risk level of 1% in 50 years
probability of collapse in the direction of maximum horizontal response with 5% damping. In general,
these risk-targeted ground motions are developed by applying adjustment factors of directivity and risk
coefficients to the 2% probability of exceedance in 50 years, or 2,475-year return period, hazard level
(MCE) ground motions developed from the 2014 USGS Unified Hazard Tool. The risk-targeted
probabilistic values are also subject to a deterministic limit. The code-based, ground-surface, MCER-level
spectrum is typically developed using the mapped bedrock spectral accelerations, Ss and Si, and
corresponding site coefficients, Fa and F,,,to account for site soil conditions.
Site Response. In accordance with Section 20.4.2 of ASCE 7-10, the site is classified as Site Class D, or a
stiff-soil site, based on an estimated Vs3o of about 1,200 ft/sec in the upper 100 ft of the soil profile.
However, our analysis has identified a potential risk of seismically induced settlement at the site. In
accordance with ASCE 7-10, sites with soils vulnerable to failure or collapse under seismic loading should
be classified as Site Class F, which requires a site-specific site-response analysis unless the structure has a
fundamental period of vibration less than or equal to 0.5 sec. The design response spectrum for sites with
structures having a fundamental period of less than or equal to 0.5 sec can be derived using the non-
liquefied subsurface profile. For periods greater than 0.5 sec, the code requires a minimum spectral
response value equal to 80% of Site Class E.
We anticipate the new structure will have a fundamental period of less than 0.5 sec; therefore, the code-
based Site Class D conditions are appropriate for design of the structure. The maximum horizontal-
direction spectral response accelerations were obtained from the USGS Seismic Design Maps for the
coordinates of 45.4141° N latitude and 122.7750° W longitude. The Ss and Si parameters identified for
the site are 0.96 and 0.42 g, respectively, for Site Class B, or bedrock conditions. To establish the ground-
surface MCER spectrum, these bedrock spectral coefficients are adjusted for site class using the short- and
long-period site coefficients, Fa and Fv, in accordance with Section 11.4.3 of ASCE 7-10. The design-level
response spectrum is calculated as two-thirds of the ground-surface MCER spectrum.
The recommended MCER- and design-level spectral response parameters for Site Class D conditions are
tabulated below and discussed in further detail in Appendix C.
RECOMMENDED SEISMIC DESIGN PARAMETERS(2012 IBC/2014 OSSC)
Recommended
Seismic Parameter Value
Site Class D
MCER 0.2-Sec Period 1.07 g
Spectral Response Acceleration,SMS
MCER 1.0-Sec Period 0.66 g
Spectral Response Acceleration,SM,
Design-Level 0.2-Sec Period
0.72 g
Spectral Response Acceleration, Sos
Design-Level 1.0-Sec Period 0.44 g
Spectral Response Acceleration, So,
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Liquefaction/Cyclic Softening. Liquefaction is a process by which loose, saturated granular materials, such
as clean sand and, to a somewhat lesser degree, non-plastic and low-plasticity silts, temporarily lose
stiffness and strength during and immediately after a seismic event. This degradation in soil properties may
be substantial and abrupt, particularly in loose sands. Liquefaction occurs as seismic shear stresses
propagate through a saturated soil and distort the soil structure, causing loosely packed groups of particles
to contract or collapse. If drainage is impeded and cannot occur quickly, the collapsing soil structure
causes the pore- water pressure to increase between the soil grains. If the pore-water pressure becomes
sufficiently large, the inter-granular stresses become small and the granular layer temporarily behaves as a
viscous liquid rather than a solid. After liquefaction is triggered, there is an increased risk of settlement,
loss of bearing capacity, lateral spreading, and/or slope instability, particularly along waterfront areas.
Liquefaction-induced settlement occurs as the elevated pore-water pressures dissipate and the soil
consolidates after the earthquake.
Cyclic softening is a term that describes a relatively gradual and progressive increase in shear strain with
load cycles. Excess pore pressures may increase due to cyclic loading but will generally not approach the
total overburden stress. Shear strains accumulate with additional loading cycles, but an abrupt or sudden
decrease in shear stiffness is not typically expected. Settlement due to post-seismic consolidation can
occur, particularly in lower-plasticity silts. Large shear strains can develop, and strength loss related to soil
sensitivity may be a concern.
The potential for liquefaction and/or cyclic softening is typically estimated using a simplified method that
compares the cyclic shear stresses induced by the earthquake (demand) to the cyclic shear strength of the
soil available to resist these stresses (resistance). Estimates of seismically induced stresses are based on
earthquake magnitude and peak ground-surface acceleration (PGA). The cyclic resistance of soils is
dependent on several factors, including the number of loading cycles, relative density, confining stress,
plasticity, natural water content, stress history, age, depositional environment (fabric), and composition.
The cyclic resistance of soils is evaluated using in-situ testing in conjunction with laboratory index testing
but may also include monotonic and cyclic laboratory strength tests. For sand-like soils, the cyclic
resistance is typically evaluated using SPT N-values or CPT tip-resistance values normalized for overburden
pressures and corrected for factors that influence cyclic resistance, such as fines content. For clay-like soils,
the cyclic resistance is typically evaluated using estimates of the undrained shear strength,
overconsolidation ratio (OCR), and sensitivity, or directly from cyclic laboratory tests.
The potential for liquefaction and/or cyclic softening at the site was evaluated using the simplified method
based on procedures recommended by Idriss and Boulanger(2008) with subsequent revisions (2014). This
method utilizes the PGA to predict the cyclic shear stresses induced by the earthquake. The USGS
National Seismic Hazard Mapping Project (NSHMP) was used to determine the contributing earthquake
magnitudes that represent the seismic exposure of the site for the MCEc hazard level. A crustal event on
the Portland Hills fault and an event on the Cascadia Subduction Zone (CSZ) were determined to represent
the sources of seismic shaking.
For our evaluation, we have considered a magnitude MW 7 crustal earthquake and MW 9 CSZ earthquake
with code-level PGAs (PGAM) of 0.45 and 0.36 g, respectively. We have conservatively assumed a
groundwater depth of about 10 ft below the ground surface, which corresponds to the anticipated highest
sustained groundwater level at the site. The results of our evaluation indicate there is potential for the
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zones of the interbedded sandy silt and silty sand deposit below the groundwater surface at the site to lose
strength or liquefy during a code-based earthquake. Based on our analysis, potentially liquefiable soils are
present below the groundwater level (10 ft) and extend to the top of the basalt. Our analysis indicates the
potential for up to 1 in. of seismically induced settlement, which may occur during the earthquake and
after earthquake shaking has ceased. Conventional geotechnical practice is to assume differential
settlements may approach 50% of the calculated total seismic settlement. Discussion of seismically
induced building foundation settlement is presented in the Foundation Support section later in this report.
Other Seismic Hazards. Based on site topography, the risk of earthquake-induced slope instability and/or
lateral spreading is low. The risk of damage by tsunami and/or seiche at the site is absent. The inferred
location of the Canby-Mollala Fault borders the southwest corner of the site (Personius et al., 2003);
however, the USGS does not consider the Canby-Mollala Fault to be an active, contributing source in their
Probabilistic Seismic Hazard Analysis (PSHA). The USGS considers the Portland Hills Fault, located about
12 km northeast of the site, to be the closest crustal fault source contributing to the overall seismic hazard
at the site. Unless occurring on a previously unmapped or unknown fault, the risk of fault rupture at the
site is low.
Earthwork
General. The fine-grained soils that mantle the site are sensitive to moisture, and perched groundwater
may approach the ground surface during the wet winter months. Therefore, it is our opinion earthwork
can be completed most economically during the dry summer months, typically extending from June to
mid-October. It has been our experience that the moisture content of the upper few feet of silty soils will
decrease during extended warm, dry weather. However, below this depth, the moisture content of the soil
tends to remain relatively unchanged and well above the optimum moisture content for compaction. As a
result, the contractor must use construction equipment and procedures that prevent disturbance and
softening of the subgrade soils. To minimize disturbance of the moisture-sensitive silt soils, site grading can
be completed using track-mounted hydraulic excavators. The excavation should be finished using a
smooth-edge bucket to produce a firm, undisturbed surface. It may also be necessary to construct granular
haul roads and work pads concurrently with excavation to minimize subgrade disturbance. If the subgrade
is disturbed during construction, soft, disturbed soils should be overexcavated to firm soil and backfilled
with structural fill.
If construction occurs during wet ground conditions, granular work pads will be required to protect the
underlying silt subgrade and provide a firm working surface for construction activities. In our opinion, a
12-to 18-in.-thick granular work pad should be sufficient to prevent disturbance of the subgrade by lighter
construction equipment and limited traffic by dump trucks. Haul roads and other high-density traffic areas
will require a minimum of 18 to 24 in. of fragmental rock, up to 6-in. nominal size, to reduce the risk of
subgrade deterioration. The use of a geotextile fabric over the subgrade may reduce maintenance during
construction. Haul roads can also be constructed by placing a thickened section of pavement base course
and subsequently spreading and grading the excess CRB after earthwork is complete.
As an alternative to the use of a thickened section of crushed rock to support construction activities and
protect the subgrade, the subgrade soils can be treated with cement. It has been our experience in this area
that treating the silt soils to a depth of 12 to 14 in. with about a 6 to 8% admixture of cement overlain by 6
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to 12 in. of crushed rock will support construction equipment and provide a good, all-weather, working
surface.
Site Preparation. Demolition of the existing improvements within the limits of the proposed
improvements should include removal of existing pavements, floor slabs, foundations, walls, and
underground utilities (if present). The ground surface within all building areas, paved areas, walkways, and
areas to receive structural fill should be stripped of existing vegetation, surface organics, and loose surface
soils. We anticipate stripping up to a depth of about 4 to 6 in. will likely be required within vegetated
areas near the northern property boundary; however, deeper grubbing may be required to remove brush
and tree roots. All demolition debris, trees, brush, and surficial organic material should be removed from
within the limits of the proposed improvements. Excavations required to remove existing improvements,
brush, and trees should be backfilled with structural fill. Organic strippings should be disposed of off site,
or stockpiled on site for use in landscaped areas.
Following stripping or excavation to subgrade level, the exposed subgrade should be evaluated by a
qualified member of GRI's geotechnical engineering staff or an engineering geologist. Proof rolling with a
loaded dump truck may be part of this evaluation. Any soft areas or areas of unsuitable material disclosed
by the evaluation should be overexcavated to firm material and backfilled with structural fill. Due to
previous development at the site, it should be anticipated some overexcavation of subgrade will be
required.
Excavation. We estimate excavations may be required to construct the retaining wall adjacent to SW 97''
Avenue. Temporary excavation slopes should be no steeper than about 1 H:1 V (Horizontal to Vertical),
and permanent cut and fill slopes should be no steeper than 2H:1 V. It should be understood the steeper
the temporary slopes, the more risk there is of sloughing of the exposed surface during construction. In our
opinion, the short-term stability of temporary slopes will be adequate if surcharge loads due to construction
and vehicle traffic are maintained an equal distance to the height of the slope away from the top of the
open cut. Other measures that should be implemented to reduce the risk of localized failures of temporary
slopes include (1) using geotextile fabric to protect the exposed cut slopes from surface erosion;
(2) providing positive drainage away from the top and bottom of the cut slopes; and (3) periodically
monitoring the area around the top of the excavation for evidence of ground cracking. It must be
emphasized that following these recommendations will not guarantee sloughing or movement of the
temporary cut slopes will not occur; however, the measures should serve to reduce the risk of a major
slope failure. It should be realized, however, that blocks of ground and/or localized slumps may tend to
move into the excavation during construction.
Depending on the depth of the excavation and the time of year the work is completed, perched
groundwater may be encountered in the excavation. We anticipate seepage, if encountered, can be
controlled by pumping from temporary sumps in the bottom of the excavation. A blanket of relatively
clean, well-graded crushed rock placed on the slopes may be required to reduce the risk of raveling soil
conditions if temporary excavation slopes encounter perched groundwater. The thickness of the granular
blanket should be evaluated based on actual conditions but would likely be in the range of 12 to 24 in.
Structural Fill. We anticipate minor amounts of structural fill will be placed for this project. We
recommend structural fill consist of granular material, such as sand, sandy gravel, or crushed rock with a
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maximum size of 2 in. Granular material that has less than 5% passing the No. 200 sieve (washed
analysis) can usually be placed during periods of wet weather. Granular backfill should be placed in lifts
and compacted with vibratory equipment to at least 95% of the maximum dry density determined in
accordance with ASTM D698. Appropriate lift thicknesses will depend on the type of compaction
equipment used. For example, if hand-operated vibratory-plate equipment is used, lift thicknesses should
be limited to 6 to 8 in. If smooth-drum vibratory rollers are used, lift thicknesses up to 12 in. are
appropriate, and if backhoe- or excavator-mounted vibratory plates are used, lift thicknesses of up to 2 ft
may be acceptable.
On-site, fine-grained soils and site strippings free of debris may be used as fill in landscaped areas. These
materials should be placed at about 90% of the maximum dry density as determined by ASTM D698. The
moisture contents of soils placed in landscaped areas are not as critical as the moisture contents of fill
placed in building and pavement areas, provided construction equipment can effectively handle the
materials.
Utility Excavations. In our opinion, there are three major considerations associated with design and
construction of new utilities.
1) Provide stable excavation side slopes or support for trench sidewalls to minimize loss
of ground.
2) Provide a safe working environment during construction.
3) Minimize post-construction settlement of the utility and ground surface.
The method of excavation and design of trench support are the responsibility of the contractor and subject
to applicable local, state, and federal safety regulations, including the current Occupational Safety and
Health Administration (OSHA) excavation and trench safety standards. The means, methods, and
sequencing of construction operations and site safety are also the responsibility of the contractor. The
information provided below is for the use of our client and should not be interpreted to mean we are
assuming responsibility for the contractor's actions or site safety.
According to current OSHA regulations, the majority of the fine-grained soils encountered in the
explorations may be classified as Type B. In our opinion, trenches less than 4 ft deep that do not encounter
groundwater may be cut vertically and left unsupported during the normal construction sequence,
assuming trenches are excavated and backfilled in the shortest possible sequence and excavations are not
allowed to remain open longer than 24 hr. Excavations more than 4 ft deep should be laterally supported
or alternatively provided with side slopes of 1 H:1V or flatter. In our opinion, adequate lateral support may
be provided by common methods, such as the use of a trench shield or hydraulic shoring systems.
We anticipate the groundwater level will typically occur below the anticipated maximum excavation
depth; however, perched groundwater may approach the ground surface during intense or prolonged
precipitation. Groundwater seepage, running soil conditions, and unstable trench sidewalls or soft trench
subgrades, if encountered during construction, will require dewatering of the excavation and trench
sidewall support. The impact of these conditions can be reduced by completing trench excavations during
the summer months, when groundwater levels are lowest, and by limiting the depths of the trenches.
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We anticipate groundwater inflow, if encountered, can generally be controlled by pumping from sumps.
To facilitate dewatering, it will be necessary to overexcavate the trench bottom to permit installation of a
granular working blanket. We estimate the required thickness of the granular working blanket will be on
the order of 1 ft, or as required to maintain a stable trench bottom. The actual required depth of
overexcavation will depend on the conditions exposed in the trench and the effectiveness of the
contractor's dewatering efforts. The thickness of the granular blanket must be evaluated on the basis of
field observations during construction. We recommend the use of relatively clean, free-draining material,
such as 2- to 4-in.-minus crushed rock, for this purpose. The use of a geotextile fabric over the trench
bottom will assist in trench-bottom stability and dewatering.
All utility trench excavations within building and pavement areas should be backfilled with relatively
clean, granular material, such as sand, sandy gravel, or crushed rock of up to 11/2-in. maximum size and
having less than 5% passing the No. 200 sieve (washed analysis). The bottom of the excavation should be
thoroughly cleaned to remove loose materials and the utilities should be underlain by a minimum 6-in.
thickness of bedding material. The granular backfill material should be compacted to at least 95% of the
maximum dry density as determined by ASTM D698 in the upper 5 ft of the trench and at least 92% of this
density below a depth of 5 ft. The use of hoe-mounted vibratory-plate compactors is usually most efficient
for this purpose. Flooding or jetting as a means of compacting the trench backfill should not be permitted.
Foundation Support
We anticipate column and wall loads will be on the order of 100 to 300 kips and 3 to 5 kips/ft,
respectively. In our opinion, the proposed structural loads can be supported on conventional spread and
wall footings in accordance with the following design criteria. As discussed earlier, our analysis indicates
up to 1 in. of settlement could occur following a code-based seismic event. Based on the thickness of the
non-liquefiable soil that mantles the site, we estimate the risk of ground manifestation of the seismically
induced settlement is generally low. For design purposes, we recommend assuming differential seismic
settlement will approach 50% of the calculated total seismic settlement over the length of the building.
The 2015 National Earthquake Hazards Reduction Program (NEHRP) document titled "Recommended
Seismic Provisions for New Buildings and Other Structures" provides guidance for acceptable limits of
seismic differential settlement for different types of structures and different risk categories. In our opinion
and based on Table 12.13-3 of 2015 NEHRP, up to 0.5 in. of seismic differential settlement over the length
of the building is acceptable and consistent with current standards of practice for a life-safety performance
level. However, the structural engineer should determine if the structure can accommodate the estimated
total and differential seismic settlement. Tying the foundations together with a network of grade beams
could be considered to help reduce the potential adverse effects associated with differential vertical
movement. The grade beams should be designed in accordance with the guidelines presented in the 2015
NEHRP document.
All footings should be established in the medium-stiff, native soil that mantles the site. The base of all new
footings should be established at a minimum depth of 18 in. below the lowest adjacent finished grade.
The footing width should not be less than 24 in. for isolated column footings and 18 in. for wall footings.
Excavations for all foundations should be made with a smooth-edge bucket, and all footing subgrades
should be observed by a member of GRI's geotechnical engineering staff. Soft or otherwise unsuitable
material encountered at foundation subgrade level should be overexcavated and backfilled with granular
GR 10
structural fill. Our experience indicates the subgrade soils are easily disturbed by excavation and
construction activities. Due to these considerations, we recommend installing a minimum 3-in.-thick layer
of compacted crushed rock in the bottom of all footing excavations. Relatively clean, 314-in.-minus crushed
rock is suitable for this purpose.
Footings established in accordance with these criteria can be designed on the basis of an allowable soil
bearing pressure of 2,500 psf. This value applies to the total of dead load and/or frequently applied live
loads and can be increased by one-third for the total of all loads: dead, live, and wind or seismic. We
estimate the total static settlement of spread and wall footings designed in accordance with the
recommendations presented above will be less than 1 in. for footings supporting column and wall loads of
up to 300 kips and 5 kips/ft, respectively. Differential static settlements between adjacent, comparably
loaded footings should be less than half the total settlement.
Horizontal shear forces can be resisted partially or completely by frictional forces developed between the
base of the footings and the underlying soil and by soil passive resistance. The total frictional resistance
between the footing and the soil is the normal force times the coefficient of friction between the soil and
the base of the footing. We recommend an ultimate value of 0.35 for the coefficient of friction for footings
cast on granular material. The normal force is the sum of the vertical forces (dead load plus real live load).
If additional lateral resistance is required, passive earth pressures against embedded footings can be
computed on the basis of an equivalent fluid having a unit weight of 250 pcf. This design passive earth
pressure would be applicable only if the footing is cast neat against undisturbed soil or if backfill for the
footings is placed as granular structural fill and assumes up to 1/2 in. of lateral movement of the structure
will occur in order for the soil to develop this resistance. This value also assumes the ground surface in
front of the foundation is horizontal, i.e., does not slope downward away from the toe of the footing.
Subdrainage/Floor Support
To provide a capillary break and reduce the risk of damp floors, slab-on-grade floors established at or
above adjacent final site grades should be underlain by a minimum 8 in. of free-draining, clean, angular
rock. This material should consist of angular rock such as 11/2- to 3/4-in. crushed rock with less than 2%
passing the No. 200 sieve (washed analysis) and should be placed in one lift and compacted to at least
95% of the maximum dry density (ASTM D698) or until well keyed. To improve workability, the drain
rock can be capped with a 2-in.-thick layer of compacted, 3/4-in.-minus crushed rock. In our opinion, it is
appropriate to assume a coefficient of subgrade reaction, k, of 175 pci to characterize the subgrade support
for point loading with 8 in. of compacted crushed rock beneath the floor slab.
In areas where floor coverings will be provided or moisture-sensitive materials stored, it would be
appropriate to also install a vapor-retarding membrane. The membrane should be installed as
recommended by the manufacturer. In addition, a foundation drain should be installed around the
building perimeter to collect water that could potentially infiltrate beneath the foundations and should
discharge to an approved storm drain.
Although it is anticipated that the finished floor elevation for the building will be established near or above
the adjacent site grades, if structures, such as floors, are established below the final site grades, the structure
should be provided with a subdrainage system. A subdrainage system will reduce the buildup of
GR 11
hydrostatic pressures on the floor slab and the risk of groundwater entering through embedded walls and
floor slabs. GRI should be contacted if embedded structures are being considered.
Retaining Walls
General. A retaining wall will likely be required to retain the cut along SW 97' Avenue to establish grade
for the new parking lot. Based on subsurface conditions, the anticipated height of the cut, and the adjacent
road, we anticipate a soldier pile and lagging wall, either cantilevered or restrained with tie-back anchors,
or a soil nail wall will be the most economical approach to providing the required structural support. We
should be contacted if other types of retaining walls are to be considered for this project.
GRI should review the final plans developed by the wall designer once they become available and
complete global external stability analyses on representative cross sections of the planned retaining walls.
Lateral Earth Pressures. Design lateral earth pressures for retaining walls depend on the type of
construction, i.e., the ability of the wall to yield. Possible conditions are 1) a wall that yields to the active
state by tilting about its base, such as a cantilever soldier pile or soil-nail wall, and 2) a wall that is laterally
supported at its base and top and therefore unable to yield to the active state, such as a tied-back soldier
pile wall.
The lateral earth pressure criteria shown on Figure 3 can be used for design of cantilevered retaining wall
systems, which assumes the wall can be allowed to yield somewhat during and after construction and
minor amounts of settlement behind the system can also be tolerated. The lateral earth pressure criteria
shown on Figure 4 can be used for design of restrained retaining wall systems to resist larger forces and/or
reduce the amount of yielding of the wall during and after construction. To account for seismic loading,
the earth pressure should be increased by 8 and 15 pcf for yielding and non-yielding walls, respectively.
This results in a triangular distribution with the resultant acting at 113H up from the base of the wall, where
H is the height of the wall in feet. Additional lateral loading due to surcharge loads can be evaluated using
the criteria shown on Figure 5.
These earth pressures assume the walls are fully drained, i.e., hydrostatic pressure cannot build up on the
back of the wall. We recommend installation of a permanent drainage system between the lagging and
fascia for soldier pile and lagging walls, and between the soil and fascia for soil-nail walls. The drainage
system should consist of continuous drainage panels between the lagging/retained soil and the face of the
wall. The drainage panels should extend to the base of the wall, where water should be collected in a
perforated pipe and discharged to an approved storm drain. In addition, the wall design should include
positive drainage measures to prevent ponding of surface water behind the top of the wall.
Soldier Pile and Lagging Walls. Lagging should be installed and any voids backfilled using controlled-
density fill, if necessary, as the excavation proceeds. The excavation should not extend more than about 1
ft below a bracing level until the tie-backs, lagging, and backfill at that level are in place.
Tied-Back Walls. For a tied-back soldier pile retaining wall, we recommend all tie-back anchors develop
their pull-out resistance beyond a no-load zone defined by a plane, as shown on Figure 4. Verification
tests should be conducted to at least 200% of the design anchor load for at least one anchor per level. The
results of the tests will be used to review and revise, if necessary, the anchor design criteria. In addition,
GRD 12
each production anchor should be proof tested to at least 133% of the design load. The shoring contractor
should have a proven record of successful shoring and tie-back installations in similar materials.
Soil-Nail Wall. We anticipate soil nail walls may be used to retain the cut. Soil nail walls can be designed
with relatively steep, near-vertical faces using reinforced shotcrete facing between the individual soil nails,
which are typically installed in drilled holes and grouted into place.
Soil nail walls typically have proprietary design and installation procedures developed by a specialty
contractor to satisfy a performance-based specification. However, soil nail walls should be designed,
constructed, and tested in substantial conformance with the guidelines provided in the Federal Highway
Administration (FHWA) Soil Nail Walls Reference Manual (FHWA-NHI-14-007). Based on a review of the
subsurface information for the site, we anticipate soil nail installation would encounter primarily silty sand
and sandy silt soils. In our opinion, it is appropriate for preliminary planning to assume the following soil
properties for the soil nail design.
Static Conditions Seismic Conditions
Moist Unit Moisture Effective Effective Undrained
Weight,pcf Content,% Friction Angle,4' Stress Cohesion,psf Shear Strength,psf
115 30 32° 0 700
It should be understood that a soil nail wall must undergo some lateral deformation to mobilize the shear
strength of the nails. Based on our experience, it is anticipated the lateral deformation could be about 1/2
in, for a 10-ft-high wall.
Additional Retaining Wall Considerations. In addition, we recommend the following performance
provisions be included in the project specifications.
1) Horizontal movement of the retaining wall system along the adjacent streets should be
accurately measured and recorded at each stage of the excavation by the contractor.
Horizontal movement should be measured at the top and at each intermediate bracing
level on at least every second soldier pile, or about every 10 ft. Settlement of the
ground surface near the adjacent street should be monitored at a minimum spacing of
20 ft along the curb line closest to the excavation.
2) Horizontal movement of the shoring system should not exceed 1/2 in. toward the
excavation.
Pavement Design
We anticipate the bus loop pavement will be subjected to bus, automobile, and light truck traffic and the
parking lot will be subjected primarily to automobile and light truck traffic, with occasional heavy truck
traffic. We anticipate the majority of the site will be paved with AC pavement; however, areas subjected to
repeated heavy truck traffic, such as trash-enclosure and service areas, may be paved with PCC pavement.
Traffic estimates for the bus loop and parking areas are presently unknown.
Based on our experience with similar projects and subgrade soil conditions, we recommend the following
pavement sections.
GRO 13
RECOMMENDED PAVEMENT SECTIONS
CRB AC
Thickness,in. Thickness,in.
Areas Subject to School-Bus Traffic(Bus 14 5
Loop)
Areas Subject to Primarily Automobile 12 4
Traffic(Service Road &Vehicle Drive Lanes)
Areas Subject to Automobile Parking 8 3
(Parking Stalls)
CRB PCC
Thickness,in. Thickness,in.
Areas Subject to Repeated Heavy Truck 6 6
Traffic(Trash-Enclosure and Service Areas)
The recommended pavement sections should be considered minimum thicknesses and underlain by a
woven geotextile fabric. It should be assumed some maintenance will be required over the life of the
pavement (15 to 20 years). The recommended pavement sections are based on the assumption pavement
construction will be accomplished during the dry season and after construction of the building has been
completed. If wet-weather pavement construction is considered, it will likely be necessary to increase the
thickness of CRB to support construction equipment and protect the subgrade from disturbance. The
indicated sections are not intended to support extensive construction traffic, such as dump trucks and
concrete trucks. Pavements subject to construction traffic may require repair.
For the above-indicated sections, drainage is an essential aspect of pavement performance. We
recommend all paved areas be provided positive drainage to remove surface water and water within the
base course. This will be particularly important in cut sections or at low points within the paved areas,
such as at catch basins. Effective methods to prevent saturation of the base course materials include
providing weep holes in the sidewalls of catch basins, subdrains in conjunction with utility excavations,
and separate trench-drain systems. To ensure quality materials and construction practices, we recommend
the pavement work conform to Oregon Department of Transportation standards.
Prior to placing base course materials, all pavement areas should be proof rolled with a fully loaded, 10-cy
dump truck. Any soft areas detected by the proof rolling should be overexcavated to firm ground and
backfilled with compacted structural fill.
Provided the pavement section is installed in accordance with the recommendations provided above, it is
our opinion the site-access areas will support infrequent traffic by an emergency vehicle having a gross
vehicle weight(GVW) of up to 75,000 lbs. For the purposes of this evaluation, "infrequent" can be defined
as once a month or less.
DESIGN REVIEW AND CONSTRUCTION SERVICES
We welcome the opportunity to review and discuss construction plans and specifications for this project as
they are being developed. In addition, GRI should be retained to review all geotechnical-related portions
of the plans and specifications to evaluate whether they are in conformance with the recommendations
provided in our report. To observe compliance with the intent of our recommendations, the design
concepts, and the plans and specifications, we are of the opinion that all construction operations dealing
with earthwork and foundations should be observed by a GRI representative. Our construction-phase
GR 14
services will allow for timely design changes if site conditions are encountered that are different from those
described in our report. If we do not have the opportunity to confirm our interpretations, assumptions, and
analyses during construction, we cannot be responsible for the application of our recommendations to
subsurface conditions different from those described in this report.
LIMITATIONS
This report has been prepared to aid the architect and engineer in the design of this project. The scope is
limited to the specific project and location described herein, and our description of the project represents
our understanding of the significant aspects of the project relevant to the design and construction of the
new foundations and floors. In the event any changes in the design and location of the project elements as
outlined in this report are planned, we should be given the opportunity to review the changes and modify
or reaffirm the conclusions and recommendations of this report in writing.
The conclusions and recommendations submitted in this report are based on the data obtained from the
explorations made at the locations indicated on Figure 2 and other sources of information discussed in this
report. In the performance of subsurface investigations, specific information is obtained at specific
locations at specific times. However, it is acknowledged that variations in soil conditions may exist
between exploration locations. This report does not reflect any variations that may occur between these
explorations. The nature and extent of variation may not become evident until construction. If during
construction, subsurface conditions differ from those encountered in the explorations, we should be
advised at once so that we can observe and review these conditions and reconsider our recommendations
where necessary.
Please contact the undersigned if you have any questions.
Submitted for GRI,
tip,EO PROFFS
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Renews 6/2018
Wesley Spang, PhD, PE, GE Nicholas M. Hatch, PE
Principal Project Engineer
This document has been submitted electronically.
References
Idriss, I.M., and Boulanger, R.W., 2008, Soil liquefaction during earthquakes: Earthquake Engineering Research Institute,
EERI MNO-12.
Idriss, I.M.,and Boulanger, R.W., 2014, CPT and SPT based liquefaction triggering procedures: Department of Civil&
Environmental Engineering,College of Engineering, University of California at Davis, Report No. UCD/CGM-14/01.
GR 15
Madin, I.P.,1990,Earthquake-hazard geology maps of the Portland metropolitan area:Oregon Department of Geology and Mineral
Studies,Open-File Report 90-02.
Personius, S. F., Dart, R. L., Bradley, Lee-Ann, and Haller, K. M., 2003, Map and data for Quaternary faults and folds in Oregon:
U.S.Geological Survey Open-File Report 03-095.
U.S.Geological Survey(USGS),Unified hazard tool,Conterminous U.S.2014(v4.0x),accessed 5/30/17 from USGS website:
https://earthquake.usgs.gov/bazards/interactive/.
GR 16
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BEAVERTON,OREG.(2014)
0 1/2 1 MILE
GR fl TIGARDY TUAILATINMIDDLESCHOOL SCHOOL DISTRICT
TWALIT
VICINITY MAP
JUNE 2017 JOB NO.5970 B FIG. 1
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JUNE 2017 100 NO.59704 IG.2
1 .
WALL
V
4
H,FT
4
4
► 4
h,FT
4(200 PCF)h (35 PCF)H+ h
(SEE NOTE 2) > (SEE NOTE 2&4)
(PASSIVE) (ACTIVE)
NOTES:
1) SURCHARGE EFFECTS FROM THE ADJACENT ROAD SHOULD BE ADDED TO THE ABOVE DESIGN PRESSURES.LATERAL LOADS ON
THE SHORING DUE TO SURCHARGE EFFECTS CAN BE COMPUTED USING THE CRITERIA PROVIDED IN FIGURE 5.HOWEVER,WE
RECOMMEND A MINIMUM ADDITIONAL VERTICAL PRESSURE OF 250 PSF BE ADDED BEHIND THE WALL.
2) FOR CANTILEVERED SOLDIER PILES WITH LAGGING,BELOW THE BOTTOM OF THE WALL,PASSIVE PRESSURE ACTS OVER TWO PILE
DIAMETERS(ACTUAL AREA),AND ACTIVE PRESSURE ACTS OVER ONE PILE DIAMETER(ACTUAL AREA)ASSUMES A MINIMUM SOLDIER
PILE SPACING OF THREE DIAMETERS.
3) DESIGN ACTIVE PRESSURES ASSUME FULLY DRAINED CONDITIONS.
4) ACTIVE PRESSURE ACTS OVER THE ENTIRE EXPOSED SHORING AND/OR WALL AREA.
5) SOLDIER PILES SHOULD EXTEND AT LEAST 5 FT BELOW THE LOWEST ADJACENT EXCAVATION LEVEL.
G f TIGARD TUALATIN SCHOOL DISTRICT
TWALITY MIDDLE SCHOOL
EARTH PRESSURES FOR
CANTILEVER WALLS
JUNE 2017 JOB NO.5970-B FIG.3
$ 4
WALL
I' 1 1=111='111-I_TI�lII-11Te11=1TI. 1=L=111 1111=
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SOLDIER PILE 30°
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TEMPORARY SHORING
H,FT A (SEE NOTE 4)
IINO LOAD
ZONE
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h,FT
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(200 PCF)h(SEE NOTE 2)
NOTES:
1) FOR TIED-BACK SOLDIER PILES WITH LAGGING,SURCHARGE EFFECTS FROM THE ADJACENT ROAD SHOULD BE
ADDED TO THE ABOVE DESIGN PRESSURES.LATERAL LOADS ON THE SHORING DUE TO SURCHARGE EFFECTS
CAN BE COMPUTED USING THE CRITERIA PROVIDED IN FIGURE 5.HOWEVER,WE RECOMMEND A MINIMUM
ADDITIONAL VERTICAL PRESSURE OF 250 PSF BE ADDED BEHIND THE WALL.
2) FOR TIED-BACK SOLDIER PILES WITH LAGGING BELOW THE BOTTOM OF THE WALL,PASSIVE PRESSURE ACTS
OVER TWO PILE DIAMETER(ACTUAL AREA).ASSUMES A MINIMUM SOLDIER PILE SPACING OF THREE DIAMETERS.
3) DESIGN PRESSURES ASSUME FULLY DRAINED CONDITIONS.
4) ACTIVE PRESSURE ACTS OVER THE ENTIRE EXPOSED SHORED AND/OR WALL AREA.
5) SOLDIER PILES SHOULD EXTEND AT LEAST 5 FT BELOW THE LOWEST ADJACENT EXCAVATION LEVEL.
GuileTIGARD TUALATIN SCHOOL DISTRICT
TWALITY MIDDLE SCHOOL
EARTH PRESSURES FOR
TIED-BACK WALLS
JUNE 2017 JOB NO,5970-B HG.4
r
< X=mH >]
STRIP LOAD,q
LINE LOAD,QL E —__a NNW
•.ii��////j ---•..iii...:.�-"ori'
n n /\ —moi "2
Z=nH
VP g
Form 50.4:
V H
a _ QL 0.2n
H
NW h _ H (0.16+n2)2 Mgr
For m >0.4:
Or
ah= 2 qQ ((3•SING COS 2a)
Qh Uh = QL 1.28m2n ah 1Y
H (m2+ n2)2 / (i3 in radians)
LINE LOAD PARALLEL TO WALL STRIP LOAD PARALLEL TO WALL
X=mH >1
r_
POINT LOAD,Qp
A t ---" / /
Z=nH Form s.0.4:
A I A' Qh = QP 0.28n2
H H2 (0.16+n2)'
--
For m >0.4:
_ Qp 1.77m2n2
oh ah H2 (m2+ n2)2
j1116,
u'h=0-11 COS2(1.10) NOTES:
/ ah 1. THESE GUIDELINES APPLY TO RIGID WALLS WITH POISSON'S
RATIO ASSUMED TO BE 0.5 FOR BACKFILL MATERIALS.
0 0 Y_, A'
2. LATERAL PRESSURES FROM ANY COMBINATION OF ABOVE
LOADS MAY BE DETERMINED BY THE PRINCIPLE OF SUPERPOSITION.
Q'h
X=mH >
DISTRIBUTION OF HORIZONTAL PRESSURES
VERTICAL POINT LOAD V R 0 TIGARD TUALATIN SCHOOL DISTRICT
TWALITY MIDDLE SCHOOL
SURCHARGE-INDUCED
LATERAL PRESSURE
)UNE 2017 JOB NO.5970-B FIG.5
APPENDIX A
Field Explorations and Laboratory Testing
APPENDIX A
FIELD EXPLORATIONS AND LABORATORY TESTING
FIELD EXPLORATIONS
Subsurface materials and conditions at the site were investigated between May 3 and May 5, 2017, with
three borings, designated B-1 through B-3; one cone penetrometer test (CPT) sounding, designated CPT-1;
and one dilatometer (DMT) sounding, designated DMT-1. The approximate locations of the explorations
completed for this investigation are shown on Figure 2. Logs of the borings, CPT probe, and DMT
sounding are provided on Figures lA through 6A. The field exploration work was coordinated and
documented by an experienced member of GRI's geotechnical engineer staff, who maintained a log of the
materials and conditions disclosed during the course of work.
Borings
Three borings, designated B-1 through B-3, were advanced to depths of about 27.8 to 51.5 ft below
existing site grades. The borings were completed with solid-stem auger drilling techniques using a trailer-
mounted drill rig provided and operated by Dan j. Fischer Excavating, Inc., of Forest Grove, Oregon.
Disturbed and undisturbed soil samples were obtained from the borings at 2.5-ft intervals of depth in the
upper 15 ft and 5- to 10-ft intervals below this depth. Disturbed soil samples were obtained using a
standard split-spoon sampler (SPT). The outside diameter of the SPT sampler was 2 in. Penetration tests
were conducted by driving the sampler into the soil a distance of 18 in. using a 140-lb hammer dropped
30 in. The number of blows required to drive the SPT sampler the last 12 in. is known as the Standard
Penetration Resistance, or SPT N-value. SPT N-values provide a measure of the relative density of granular
soils and relative consistency of cohesive soils. Samples obtained from the borings were placed in airtight
jars and returned to our laboratory for further classification and testing. In addition, relatively undisturbed
samples were collected by pushing a 3-in.-outside-diameter (O.D.) Shelby tube into the undisturbed soil a
maximum distance of 24 in. using the hydraulic ram of the drill rig. The soil exposed in the end of the
Shelby tube was examined and classified in the field. After classification, the tube was sealed with rubber
caps and returned to our laboratory for further examination and testing.
Logs of the borings are provided on Figures 1A through 3A. Each log presents a descriptive summary of
the various types of materials encountered in the boring and notes the depths at which the materials and/or
characteristics of the materials change. To the right of the descriptive summary, the numbers and types of
samples are indicated. Farther to the right, SPT N-values are shown graphically, along with the natural
moisture contents, Torvane shear strength values, and percent passing the No. 200 sieve, where
applicable. The terms and symbols used to describe the materials encountered in the borings are defined
in Table 1A and the attached legend.
Electric Cone Penetration Test
One electric CPT probe, designated CPT-1, was advanced to a depth of about 26.3 ft using a truck-
mounted CPT rig provided and operated by Oregon Geotechnical Explorations, Inc., of Keizer, Oregon.
During the CPT, a steel cone is forced vertically into the soil at a constant rate of penetration. The force
required to cause penetration at a constant rate can be related to the bearing capacity of the soil
GR A-1
immediately surrounding the point of the penetrometer cone. This force is measured and recorded every
8 in. In addition to the cone measurements, measurements are obtained of the magnitude of force required
to force a friction sleeve, attached above the cone, through the soil. The force required to move the friction
sleeve can be related to the undrained shear strength of fine-grained soils. The dimensionless ratio of
sleeve friction to point bearing capacity provides an indicator of the type of soil penetrated. The cone-
penetration resistance and sleeve friction can be used to evaluate the relative consistency of cohesionless
and cohesive soils, respectively. In addition, a piezometer fitted between the cone and the sleeve
measures changes in water pressure as the probe is advanced and can also be used to measure the depth of
the top of the groundwater table. The probe was also operated using an accelerometer fitted to the probe,
which allows measurement of the arrival time of shear waves from impulses generated at the ground
surface. This allows calculation of shear-wave velocities for the surrounding soil profile.
A log of the electric CPT probe is provided on Figure 4A, which presents graphical summaries of the tip
resistance, local (sleeve) friction, friction ratio, pore pressure, and soil behavior type (SBT) index. The terms
used to describe the soils encountered in the probe are defined in Table 2A. Shear-wave velocity
measurements were recorded for the probe and are shown on Figure 5A.
Dilatometer Test
One DMT sounding, designated DMT-1, was advanced to a depth of about 34 ft using a truck-mounted
CPT rig provided and operated by Oregon Geotechnical Explorations, Inc., of Keizer, Oregon. DMT
soundings provide additional geotechnical information to characterize the subsurface materials. The
dilatometer test is performed 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 pressures required to move the membrane to a point flush with the
blade (Po— pressure) and 1.1 mm into the surrounding soil (Pi — pressure) are recorded. The test sequence
was performed at 8-in. intervals to obtain a comprehensive soil profile. A material index (ID), horizontal
stress index (KD), and dilatometer modulus (ED) are obtained directly from the dilatometer data. The
constrained modulus (M) is then obtained from the dilatometer data.
The dilatometer test results are summarized on Figure 6A. The results show the dilatometer pressure
readings (Po, Pi) and three dilatometer-derived parameters: horizontal stress index (KD), material index (ID),
and constrained modulus (M). The terms used to describe the materials encountered in the sounding are
defined in Table 3A.
LABORATORY TESTING
General
The samples obtained from the borings were examined in our laboratory, where the physical characteristics
of the samples were noted and the field classifications modified where necessary. At the time of
classification, the natural moisture content of each sample was determined. Additional testing included
Torvane shear strength, dry unit weight, and grain size. A summary of the laboratory test results has been
provided in Table 4A. The following sections describe the testing program in more detail.
Natural Moisture Content
Natural moisture content determinations were made in conformance with ASTM D2216. The results are
summarized on Figures 1A through 3A and in Table 4A.
GRO A-2
Torvane Shear Strength
The approximate undrained shear strength of the fine-grained soils was determined using a Torvane shear
device. The Torvane is a hand-held apparatus with vanes that are inserted into the soil. The torque
required to fail the soil in shear around the vanes is measured using a calibrated spring. The results of the
Torvane shear strength tests are summarized on Figures 1 A and 2A.
Undisturbed Unit Weight
The unit weight, or density, of undisturbed soil samples was determined in the laboratory in
conformance with ASTM D2937. The results are summarized on Figures 1A and 2A and in Table 4A.
Grain-Size Analysis
Washed-Sieve Method. To assist in classification of the soils, samples of known dry weight were washed
over a No. 200 sieve. The material retained on the sieve was oven-dried and weighed. The percentage of
material passing the No. 200 sieve was then calculated. The results are summarized on Figures 1A through
3A and in Table 4A.
G R 8 A-3
Table 1A
GUIDELINES FOR CLASSIFICATION OF SOIL
Description of Relative Density for Granular Soil
Standard Penetration Resistance
Relative Density (N-values),blows per ft
very loose 0-4
loose 4- 10
medium dense 10-30
dense 30-50
very dense over 50
Description of Consistency for Fine-Grained(Cohesive)Soils
Standard Penetration Torvane or
Resistance(N-values), Undrained Shear
Consistency blows per ft Strength,tsf
very soft 0-2 less than 0.125
soft 2-4 0.125-0.25
medium stiff 4-8 0.25-0.50
stiff 8-15 0.50- 1.0
very stiff 15-30 1.0-2.0
hard over 30 over 2.0
Grain-Size Classification Modifier for Subclassification
Boulders: Primary Constituent Primary Constituent
>12 in. SAND or GRAVEL SILT or CLAY
Cobbles: Adjective Percentage of Other Material(by weight)
3- 12 in. trace: 5- 15 (sand,gravel) 5-15 (sand,gravel)
Gravel: some: 15-30(sand,gravel) 15-30(sand,gravel)
1/4 3/4 in. (fine) sandy,gravelly: 30-50(sand,gravel) 30-50(sand,gravel)
3/4-3 in. (coarse)
Sand: trace: <5 (silt,clay)
No. 200-No.40 sieve(fine) Relationship of clay and
No.40-No. 10 sieve(medium) some: 5 12 (silt, clay) silt determined by
No. 10-No.4 sieve(coarse) silty, clayey: 12-50(silt,clay) plasticity index test
Silt/Clay:
pass No. 200 sieve
Table 2A: CONE PENETRATION TEST(CPT)CORRELATIONS
COHESIVE SOILS
Cone-Tip Resistance,tsf Consistency
<5 Very Soft
5 to 15 Soft to Medium Stiff
15 to 30 Stiff
30 to 60 Very Stiff
>60 Hard
COHESIONLESS SOILS
Cone-Tip Resistance,tsf Relative Density
<20 Very Loose
20 to 40 Loose
40 to 120 Medium
120 to 200 Dense
>200 Very Dense
Reference
Kulhawy,F.H.,and Mayne,P.W., 1990,Manual on estimating soil properties for foundation design:Electric Power Research
Institute,EL-6800.
V 1
Table 3A: SOIL CHARACTERIZATION
BASED ON MARCHETTI FLAT-PLATE DILATOMETER TEST
Description of Consistency for Fine-Grained(Cohesive)Soils
Soil Type("
CH, CL ML, MH
DMT Constrained Modulus(MONY),tsf
Consistency ID2'< 0.6 0.6 <ID2)< 1.8
Very Soft 0-30 0- 50
Soft 30-60 50- 100
Medium Stiff 60- 100 100-200
Stiff 100- 175 200-375
Very Stiff 175 + 375 +
Description of Relative Density for Granular Soils
Soil Type"'
SM, SC SP, SW
DMT Constrained Modulus(MONY),tsf
tz)
Relative Density 1.8 <Ip < 3.3 3.3 <Ip(2)
Very Loose 0-75 0- 100
Loose 75 - 150 100-200
Medium Dense 150-300 200-425
Dense 300-550 425 -850
Very Dense 550 + 850 +
1) Unified Soil Classification System
2) ID = Material Index
r ,
Table 4A
SUMMARY OF LABORATORY RESULTS
Sample Information Atterberg Limits
Moisture Dry Unit Liquid Plasticity Fines
Location Sample Depth,ft Elevation,ft Content, % Weight,pcf limit, % Index, % Content, % Soil Type
B-1 S-1 2.8 - 28 - - - 57 Sandy SILT
S-1 3.7 - 30 91 - - - Sandy SILT
S-2 4.5 - 32 - - - - Sandy SILT
S-3 7.5 - 28 - - -- 29 Silty SAND
S-4 10.0 - 20 - - - 28 Silty SAND
S-5 12.5 - 33 - - - - Silty SAND
S-5 13.0 - 17 -- - - - Silty SAND
S-6 15.0 - 19 - - - 28 Silty SAND
S-7 20.0 - 25 - - -- - Silty SAND
S-8 25.0 - 21 - - - - Silty SAND
S-9 30.0 - 30 - - -- 19 Silty SAND
S-10 35.0 - 27 - - - - Silty SAND
S-10 36.0 - 29 - - - - Silty SAND
B-2 S-1 2.5 -- 24 - - - 51 Sandy SILT
S-2 5.7 - 30 91 -- - 57 Sandy SILT
S-3 6.1 - 29 - - - - Sandy SILT
S-4 10.0 - 27 - - -- 67 Sandy SILT
S-5 12.8 - 27 - - - 57 Sandy SILT
S-5 14.2 - 28 94 - - - Sandy SILT
S-6 14.5 - 25 - - - - Sandy SILT
S-7 20.0 - 32 - - - - Sandy SILT
S-8 25.0 - 31 -- - - - Clayey SILT
B-3 S-1 2.5 - 24 - - - - Silty SAND
S-2 5.0 - 29 - - -- 47 Silty SAND
S-3 7.5 - 27 - - - - Silty SAND
5-4 10.0 - 18 - - - 18 Silty SAND
S-5 12.5 - 18 -- - - - Silty SAND
S-6 15.0 - 27 - - - - Silty SAND
S-7 20.0 - 31 - - -- - Silty SAND
S-8 25.0 - 29 - - - 25 Silty SAND
S-9 30.0 - 33 - - - - Silty SAND
S-10 35.0 - 27 - - - 33 Silty SAND
S-11 40.0 - 27 - - - - Silty SAND
S-11 41.0 - 32 - - - - Silty SAND
S-12 50.0 - 30 - - - - Clayey SILT
Effi" g Page 1 of 1
BORING AND TEST PIT LOG LEGEND
SOIL SYMBOLS SAMPLER SYMBOLS
Symbol Typical Description Symbol Sampler Description
' " 2.0-in.O.D. split-spoon sampler and Standard
LANDSCAPE MATERIALS Penetration Tst wh recovery (ASTM D1586)
*kit tube sampler with recovery
FILLI
(ASTM D1587)
°�` 3.0-in. O.D. split-spoon sampler with recovery
5 a GRAVEL; clean to some silt,clay, and sand
(ASTM D3550)
;: Sandy GRAVEL;clean to some silt and clay N Grab Sample
INSilty GRAVEL; up to some clay and sand Rock core sample interval
woi Clayey GRAVEL; up to some silt and sand i
i Sonic core sample interval
SAND; clean to some silt, clay,and gravel Geoprobe sample interval
Gravelly SAND; clean to some silt and clay
�'.` INSTALLATION SYMBOLS
Silty SAND; up to some clay and gravel Symbol Symbol Description
;1 Clayey SAND; up to some silt and gravel Flush mount monument set in concrete
SILT• upto some clay, sand andgravel ;
y Concrete, well casing shown where applicable
o— r
. Gravelly SILT; up to some clay and sand Bentonite seal, well casing shown where
- / applicable
Sandy SILT; up to some clay and gravel Filter pack, machine-slotted well casing shown
• where applicable
//1 Clayey SILT; up to some sand and gravel J Grout, vibrating-wire transducer cable shown
/ where applicable
//y CLAY; up to some silt, sand, and gravel Vibrating-wire pressure transducer
rico Gravelly CLAY; up to some silt and sand 1-in.-diameter solid PVC
q Sandy CLAY; up to some silt and gravel ;
1-in.-diameter hand slotted PVC
// Silty CLAY; up to some sand and gravel Grout, inclinometer casing shown where
7 applicable
•w.
v" PEAT
FIELD MEASUREMENTS
BEDROCK SYMBOLS Symbol Typical Description
Symbol Typical Description 2 Groundwater level during drilling and date
- measured
c., +++ BASALT t Groundwater level after drilling and date
measured
0
F = MUDSTONE �� Rock core recovery(%)
W = SILTSTONE � Rock quality designation (R D, %)
1- (RQD,
o -_- SANDSTONE
Fe'
W SURFACE MATERIAL SYMBOLS
Symbol Typical Description
8
o
a III Asphalt concrete PAVEMENT
W M Portland cement concrete PAVEMENT
0
z
a by k
z aCy Crushed rock BASE COURSE
Fc
0
03
z w A BLOWS PER FOOT
p CLASSIFICATION OF MATERIAL o o a z • MOISTURE CONTENT,%
J
'i c� LL w w O 0 FINES CONTENT,%
_ _ = J 1.-- —LIQUID LIMIT,% COMMENTS AND
I- g a 00 g o PLASTIC LIMIT,
w w w ¢ ¢ J ADDITIONAL TESTS
o o Surface Elevation:Not Available o ? cry cn m 50 100
Sandy SILT,brown,medium stiff,fine-to — I I I - - I
—.....• medium-grained sand,3-in:thick heavily rooted
: zone at ground surface I i
_o35T—1L — _
— • ♦♦ o.aq
- ---soft to medium stiff below 4 ft s-i —`_Ir♦ rt Dry Density=91 pcf
S-2 2 4_ i
2 1
f
— Silty SAND,brown,loose,fine to medium grained 7.5'::,.::i 3 8f
S-3 e 3 — al
1 5 J
10 --interbedded with 2 to 6 in.thick layers of silt with T !/
? some sand and trace day below 10 ft s4 1 4 8 �— _
v — I
• i a
:: ::: --medium dense below 12.5 ft
3 11 —
�:.:.:; fr
I 4 _
1 7 Increased drilling
. . i resistance below 14 ft
S6 5 • ❑
8 ,— _�
_ I
i
:. i:`. I
.}: S-7 1 5 •
8 1
— —t
1
1 _ —
1
25—:.;.;, --loose to medium dense at 25 ft
s 10' I
N _ 1n
`° S-8 e 1 r 4 6
0
o
O..
t
Li, —> ::.` I—I — — V29.0 ft(5/4/2017)
0 30� —loose below 30 ft z '7 ._
S-9 1 4 ❑ -- - —
r _ 3 f �,
O
w 1
o — I
Z I I—
a _ 5-10 1 44 _
o
o �,
J
Z — - - — Increased drilling
a
o - resistance below 38 ft
m
Er" bib-
(CONTINUED NEXT PAGE) 0 0.5 1.0
Logged By:C.Jones Drilled by:Dan J.Fischer Excavating,Inc. • TORVANE SHEAR STRENGTH,TSF
Date Started:5/4/17 Coordinates:Not Available ■ UNDRAINED SHEAR STRENGTH,TSF
Drilling Method: Solid-Stem Auger Hammer Type:Manual
Equipment: Buck Rogers 160 Trailer-Mounted Rig Weight:140 lb G RO B®RING B-1
Hole Diameter: 4 in. Drop:30 in.
Note:See Legend for Explanation of Symbols Energy Ratio:Not Available
JUNE 2017 JOB NO.5970-B FIG.1A
0 z u, ♦ BLOWS PER FOOT
o CLASSIFICATION OF MATERIAL o d °
F- o • MOISTURE CONTENT, /°
LL v ��. -3 w w o 0 FINES CONTENT,%
_ _ _ - J �.(-LIQUID LIMIT,% COMMENTS AND
W w z a s o PLASTIC LIMIT,% ADDITIONAL TESTS
o o Surface Elevation:Not Available o CO CO m
9 50+++ BASALT,gray,predominantly decomposed to 40,5 s 11T5015" X51
— decomposed,extremely soft to very soft(RO to R1),
joints and fractures stained rust and filled with black
•••• __ =�
secondary mineralization l/iii.
(5/4/2017) l•Ill§ —
-
45- I
50- I -
� F_
55-
-
60-
_ i
I _
65-
N ' 1001_
p _
F
o I
IL--I —_
— I _
a I -
a 70- T r
> -
W
W
ZI III
Z _
0 75-
g — — ,
° iii..•/
Z —
0 Ill _BUUM UM
a
0
m -
o--80 I 1 I
0 0.5 I 1.0
• TORVANE SHEAR STRENGTH,TSF
■ UNDRAINED SHEAR STRENGTH,TSF
CR1 BORING B-1
JUNE 2017 JOB NO.5970-B FIG.1A
Z L A BLOWS PER FOOT
o CLASSIFICATION OF MATERIAL o a 1-o I— i= o • MOISTURE CONTENT,
LL LL. S w w 0 0 FINES CONTENT,%
_ _ -a. ' ��LIQUID LIMIT,% COMMENTS AND
F--
9,-x a- ~ Z o PLASTIC LIMIT,%
o Surface Elevation:Not Available o z cn `cn m o 50 100 ADDITIONAL TESTS
Mir Asphalt concrete PAVEMENT(2 in.)over crushed I
—^Q`�crock BASE COURSE(14 in.) . 1.3 -'
— . • Sandy SILT,trace clay,red-brown,soft to medium
_ , stiff,fine-to medium-grained sand 1 4_ i _
S-1 12 1 ; _ ❑
_ 1 vl_• ;
5 --medium stiff below 5 ft ' — iINii.040 0.55
. • --stiff at 6 ft S-2 _ ILI Dry Density=91 pcf
4 .11
S-3 1r 5
6 — I
10—••: 3 5 1
—. S-4I 2 a
3
S-5 ■irni 0.30
I — Dry Density=94 pcf
3 _10I —
15.0 56 5
Silty SAND,brown,loose to medium dense,fine to —
•-.',...::.• medium grained 5 I
I
I
I
20 Sandy SILT,brown,medium stiff,fine-to 20.0 2 6 + —
—. . - medium-grained sand S-7 I a -i. . .1111 ft . X21.0 ft(5/3/2017)
I
25--= --clayey,trace to some sand,stiff below 25 ft 3 —s
<71 S-8 1 4
ILIc°� 0�'� - -1 2.5Drill rig chatter below
lij ,-, .r _ 27.5 — _
— BASALT,gray,predominantly decomposed to 27 6 S-9 �son.5^ �� 27 ft
m _ decomposed,extremely soft to very soft(RO to R1), III „� _� —
I-- joints and fractures stained rust and filled with black _ �_1 L
30— secondary mineralization , 1 I , ! ,
o ,-1 - - t I_ ------
R _ (5!312017)
W
J
W _ I
O
z
i -
I
z
O 35—
r
—
o —
J
0
z — — —
0
0
co
(3-40 I I I
0 0.5 1.0
Logged By:C.Jones Drilled by:Dan J.Fischer Excavating,Inc. • TORVANE SHEAR STRENGTH,TSF
Date Started:5/3/17 Coordinates:Not Available ■ UNDRAINED SHEAR STRENGTH,TSF
Drilling Method: Solid-Stem Auger Hammer Type:Manual
Equipment: Buck Rogers 160 Trailer-Mounted Rig Weight:140 lb G R_O BORING B-2
Hole Diameter: 4 in. Drop:30 in.
Note:See Legend for Explanation of Symbols Energy Ratio:Not Available
JUNE 2017 JOB NO.5970-B FIG.2A
ca z IL A BLOWS PER FOOT
CLASSIFICATION OF MATERIAL o a
1. —I I— H z I- • MOISTURE CONTENT,
IL v " 1 w w ov 0 FINES CONTENT,%
i-tua 9,--±
it ¢ a a f""'I—LIQUID LIMIT,% COMMENTS AND
w w c~n ¢ ¢ o PLASTIC LIMIT,% ADDITIONAL TESTS
o o Surface Elevation:Not Available o ? cn co m 0 50 100
o,—r Asphalt concrete PAVEMENT(2 in.)over crushed _ 0'7
`rock BASE COURSE(6 in.) / --
' Silty SAND,brown mottled rust,very loose to loose,
fine to medium grained 3I --
1 _ —
4J
S-1 3 r _
5-::,.:t:: --loose at 5 ft 1 a__ �1 —
S-2 1 2 • tL
s I
---medium dense below 7.5 ft I
a IL
I
S 3 I 8 .9c '—
S-4 6
5
I
—loose below 12.5 ft 3 I
I4 4
4 N
15-- ---interbedded with 3-in.-thick layer of sandy silt at \�
15ft 2 7
"' s.64 7. X16.0 ft(5/3/2017)
111
1
2 5
57 1 2iii 111 11
25—: ':;: ---very loose at 25 ft t 4 011I
2 I I
3
� i
w t —
w
I
a I — —
I 1
S-9 3 r-----rL
W
z
O 35.-:; ;: 5--medium dense at 35 ft 1
4
S-10I 7 '
0
o —
0
z
0
m
(CONTINUED NEXT PAGE) 0 0.5 1.0
Logged By:C.Jones Drilled by:Dan J.Fischer Excavating,Inc. • TORVANE SHEAR STRENGTH,TSF
Date Started:5/3/17 Coordinates:Not Available ® UNDRAINED SHEAR STRENGTH,TSF
Drilling Method: Solid-Stem Auger Hammer Type:Manual
Equipment: Buck Rogers 160 Trailer-Mounted Rig Weight:140 lb /" `1 R j` BORING
0^INGB_3
Hole Diameter: 4 in. Drop:30 in. (`J,r t( K
Note:See Legend for Explanation of Symbols Energy Ratio:Not Available
JUNE 2017 JOB NO.5970-B FIG.3A
t .
COZ ILI 1-- A BLOWS PER FOOT
o CLASSIFICATION OF MATERIAL o _.; Cl. z • MOISTURE CONTENT,%
Li- 0 LL til LIJ 8 0 FINES CONTENT,%
LIQUID LIMIT,% COMMENTS AND
o
LU - < < -J PLASTIC LIMIT,% ADDITIONAL TESTS
D o Surface Elevation:Not Available a -.. co co m
50 100
....•, 1 / 1111 L1
i:...:.-...f:. Silty SAND,brown mottled rust,very loose to loose,
s-i 1 1 1 i
—.:.......::, fine to medium grained 3 1
:.*:'..:•::. _ _
45--:,.:.::•:':::.
T.:.-:•:.3:.
:-..:...,..
507 Clayey SILT,some fine-to medium-grained sand, 50.0
3 10
S-12
1 , _/ gray,stiff 5 1_ _
51.5 _
— (5/3/2017)
551
I I
—
_
—
1 ' 1
-
- 1111 1 1
..':.- 65—
_ 111 1 I 1
I I
1 i
0 —
m _
w LH —
a
I-- 70—
<
Ee'
o
> _ =
L11
_I
11J _
0
Z
a ilii - MINIM_ fi
z
O 75— MIEN J .1 1_1_
_.,
i-L-
_
..,
O mu moo Ns -
z _2 I 1
-Cc 1 1
°—80
0 0.5 1.0
• TORVANE SHEAR STRENGTH,TSF
• UNDRAINED SHEAR STRENGTH,TSF
,
GRA BORING B-3
JUNE 2017 JOB NO.5970-B FIG.3A
SPT N60 SBT Tip COR Sleeve Stress F.Ratio Pore Pressure
(UNITLESS) (UNITLESS) (tsf) (tsf) (%) (psi)
0 0 70 0 12 0 450 0 3 0 7 -20 100
I I I 1 I 1 1 1 1 11 I 1 I 11 1 1 1 1 1 1 1 1 I I 1 I I 1 1 1 J 1 1 1 1
1
1
,
ti 1
5 — Lilp — — _ _
ri
10 — k,y: — — — —
Depth 15 —
(ft) — —
1
:.
L'ii w. :**01'701**- -`',44 1
( ''',- ,Mq I
I
25 —cri
— - —
I r ~ - iI
30
TOTAL DEPTH:26.247 ft
;� 1 sensitive fine grained , 4 silty clay to clay 7 silty sand to sandy silt 10 gravelly sand to sand
2 organic material 5 clayey silt to silty clay 8 sand to silty sand 11 very stiff fine grained(*)
3 clay 6 sandy silt to clayey silt St 9 sand 12 sand to clayey sand(*)
*SBT/SPT CORRELATION: USC-1983
G R
Observed By: N.Hatch Advanced By:Oregon Geotechnical Explorations,Inc.
Date Started: 05/5/17 Ground Surface Elevation: Not Available
Coordinates: NotAvailable CONE PENETRATION TEST CPT-1
JUNE 2017 JOB NO. 5970-B FIG. 4A
Seismic Velocity
(Ws)
0 0 1200
i i i i i
1014
5 —
1073
10 — 677 Ii
663
Depth 15 —
(ft)
741
20 — 855
875
25 —
30 —
TOTAL DEPTH:26.247 ft
G R11
Observed By: N.Hatch Advanced By:Oregon Geotechnical Explorations,Inc.
Date Started: 05(5!17 Ground Surface Elevation: Not Available CONE PENETRATION TEST CPT-1
Coordinates: Not Available
(SEISMIC VELOCITY PROFILE)
JUNE 2017 JOB NO. 5970-B FIG. 5A
Po, P, ,tsf Ip K0 M,tsf
0 5 10 15 20 25 30 35 0.01 0.1 1 10 0 10 20 30 40 0 500 1,000 1,500
° I l linin I I HIM! i i HIM 1 1 1 1 1 1 1 1 1 1 1 J 1 1 1 < < E 1 1 1 1 1 1 i 1 1 1 1 1
5
A Po
• P,
10 —
15
.0 —
Q. —
v
20
25
30 —
35
GR
DILATOMETER SOUNDING
D\AT-1
JUNE 2017 JOB NO. 5970-B FIG. 6A
•
APPENDIX B
Templeton Elementary School Project Subsurface Logs and Laboratory Results
Table 1A
GUIDELINES FOR CLASSIFICATION OF SOIL
Description of Relative Density for Granular Soil
Standard Penetration Resistance
Relative Density (N-values),blows per ft
very loose 0-4
loose 4- 10
medium dense 10-30
dense 30-50
very dense over 50
Description of Consistency for Fine-Grained(Cohesive)Soils
Standard Penetration Torvane or
Resistance(N-values), Undrained Shear
Consistency blows per ft Strength,tsf
very soft 0-2 less than 0.125
soft 2-4 0.125-0.25
medium stiff 4-8 0.25-0.50
stiff 8- 15 0.50- 1.0
very stiff 15-30 1.0-2.0
hard over 30 over 2.0
Grain-Size Classification Modifier for Subclassification
Boulders: Primary Constituent Primary Constituent
>12 in. SAND or GRAVEL SILT or CLAY
Cobbles: Adjective Percentage of Other Material(by weight)
3 12 in. trace: 5- 15 (sand,gravel) 5- 15 (sand, gravel)
Gravel: some: 15-30(sand,gravel) 15-30(sand,gravel)
1/4 3/4 in. (fine) sandy,gravelly: 30-50(sand,gravel) 30-50(sand,gravel)
3/4-3 in. (coarse)
Sand: trace: <5 (silt,clay)
No. 200-No.40 sieve(fine) Relationship of clay and
No.40-No. 10 sieve(medium) some: 5-12 (silt, clay) silt determined by
No. 10-No.4 sieve(coarse) silty, clayey: 12-50 (silt,clay) plasticity index test
Silt/Clay:
pass No. 200 sieve
Table 2A: CONE PENETRATION TEST(CPT) CORRELATIONS
COHESIVE SOILS
Cone-Tip Resistance,tsf Consistency
<5 Very Soft
5 to 15 Soft to Medium Stiff
15 to 30 Stiff
30 to 60 Very Stiff
>60 Hard
COHESIONLESS SOILS
Cone-Tip Resistance,tsf Relative Density
<20 Very Loose
20 to 40 Loose
40 to 120 Medium
120 to 200 Dense
>200 Very Dense
Reference
Kulhawy,F.H.,and Mayne,P.W., 1990,Manual on estimating soil properties for foundation design:Electric Power Research
Institute,EL-6800.
Table 3A: SOIL CHARACTERIZATION
BASED ON MARCHETTI FLAT-PLATE DILATOMETER TEST
Description of Consistency for Fine-Grained(Cohesive)Soils
Soil Type"'
CH, CL ML, MH
DMT Constrained Modulus(MDMr), tsf
Consistency Io(2)< 0.6 0.6 <ID(2'< 1.8
Very Soft 0-30 0- 50
Soft 30-60 50- 100
Medium Stiff 60- 100 100-200
Stiff 100- 175 200- 375
Very Stiff 175 + 375 +
Description of Relative Density for Granular Soils
Soil Type
SM, SC SP, SW
DMT Constrained Modulus(Mohr),tsf
Relative Density 1.8 <Ip 2'< 3.3 3.3 <I0(2)
Very Loose 0-75 0- 100
Loose 75 - 150 100-200
Medium Dense 150- 300 200-425
Dense 300- 550 425 -850
Very Dense 550 + 850 +
1) Unified Soil Classification System
2) ID = Material Index
Table 4A
SUMMARY OF LABORATORY RESULTS
Sample Information Atterberg Limits
Moisture Dry Unit Liquid Plasticity Fines
Location Sample Depth, ft Elevation,ft Content, % Weight,pcf Limit, % Index, % Content,% Soil Type
B-1 S-1 2.5 - 24 - - - - Sandy SILT
S-2 5.3 - 31 - - -- 62 Sandy SILT
S-2 6.3 - 31 90 - - - Sandy SILT
S-3 6.8 - 32 - - - 45 Sandy SILT
S-4 10.3 - 28 - - - 24 Silty SAND
S-4 11.1 - 25 96 - - - Silty SAND
S-5 11.7 - 26 - - - - Silty SAND
S-6 15.0 - 29 - - - 18 Silty SAND
S-7 20.0 - 33 - - - - Silty SAND
S-8 25.0 - 33 - - - - Silty SAND
S-9 30.0 - 30 - - - - Silty SAND
S-10 35.0 - 24 - - - 36 Silty SAND
5-1 1 40.0 - 35 - - - - Silty SAND
B-2 5-1 2.8 - 31 - - - 64 Sandy SILT
5-1 3.5 - 37 83 - - - Sandy SILT
S-2 4.3 - 29 - - - - Sandy SILT
S-3 7.5 - 28 - - - 22 Silty SAND
S-4 10.0 - 31 - - - - Silty SAND
S-5 12.5 - 31 - - - - Silty SAND
S-6 15.0 - 30 - - - - Silty SAND
S-7 20.0 - 29 - - - 39 Silty SAND
S-8 25.0 - 27 - - - - SAND
S-9 30.0 - 29 - - - - SAND
S-10 40.0 - 31 - - - - SAND
8-3 5-1 2.8 - 29 92 - - - Silty SAND
S-1 3.7 - 27 - - - 47 Silty SAND
S-2 4.5 - 29 - - - - Sandy SILT
S-4 10.0 - 39 - - - - Sandy SILT
S-4 11.0 - 24 - - - 20 Silty SAND
S-5 12.5 - 30 - - - 56 Sandy SILT
S-6 15.0 - 30 - - - - Silty SAND
S-7 20.0 - 32 - - - - Silty SAND
S-8 25.0 - 28 - - - 29 Silty SAND
S-9 30.0 - 30 - - - - Silty SAND
S-9 30.5 - 29 - - - - Silty SAND
S-10 40.0 - 26 - - - 27 Silty SAND
G r .. EI Page 1 of 1
BORING AND TEST PIT LOG LEGEND
SOIL SYMBOLS SAMPLER SYMBOLS
Symbol Typical Description Symbol Sampler Description
'� .. LANDSCAPE MATERIALS 2.0-in. O.D. split-spoon sampler and Standard
+a I Penetration Test with recovery(ASTM D1586)
ii..**::,
�'�' FILL Shelby tube sampler with recovery
(ASTM D1587)
�` 3.0-in.O.D. split-spoon sampler with recovery
° c GRAVEL; clean to some silt,clay,and sand
, (ASTM D3550)
(5,4'i
° Sandy GRAVEL; clean to some silt and clay Grab Sample
INSilty GRAVEL; up to some clay and sand fil Rock core sample interval
dClayey GRAVEL; up to some silt and sand ,,, Sonic core sample interval
SAND; clean to some silt, clay, and gravel Geoprobe sample interval
Q' y`•' Gravelly SAND;clean to some silt and clay
��'''`' INSTALLATION SYMBOLS
'''•, G
ySilty SAND; up to some clay and gravel Symbol Symbol Description
{..',:i' Clayey SAND; up to some silt and gravel Flush mount monument set in concrete
SILT; up to some clay, sand, and gravel Concrete, well casing shown where applicable
Gravelly SILT; up to some clay and sand . r Bentonite seal, well casing shown where
applicable
Sandy SILT; up to some clay and gravel – Filter pack, machine-slotted well casing shown
- where applicable
/// Clayey SILT; up to some sand and gravel I Grout,vibrating-wire transducer cable shown
where applicable
// CLAY; up to some silt, sand,and gravel 0Vibrating-wire pressure transducer
Gravelly CLAY; up to some silt and sand ® 1-in.-diameter solid PVC
'.61 Sandy CLAY; up to some silt and gravel I
1-in.-diameter hand slotted PVC
/// Silty CLAY; up to some sand and gravel Grout, inclinometer casing shown where
applicable
w`r
.`S PEAT
FIELD MEASUREMENTS
BEDROCK SYMBOLS Symbol Typical Description
Symbol Typical Description a Groundwater level during drilling and date
measured
+++ BASALT t Groundwater level after drilling and date
o +++ measured
W -,--' MUDSTONE
5 Rock core recovery(%)
Q.
— SILTSTONE quality designation (RQD, %)
fj
SANDSTONE
0
0
W SURFACE MATERIAL SYMBOLS
0
Symbol Typical Description
0
0
a
Asphalt concrete PAVEMENT
to
F-
tu
Portland cement concrete PAVEMENT
0
< plJ t
0 3° Crushed rock BASE COURSE
re
0
03
A BLOWS PER FOOT
J CLASSIFICATION OF MATERIAL o o a ? • MOISTURE CONTENT,%
v Ii g w o 0 FINES CONTENT,% COMMENTS AND
_ a a a LIQUID LIMIT,%
al-":.. qa w c, ¢ ¢ o ~-PLASTIC LIMIT,% ADDITIONAL TESTS
o c9 Surface Elevation: Not Available o z co co Co 50 100
Sandy SILT,trace clay,dark brown,medium stiff, I ; I '_i__
-. •. fine-to medium-grained sand,3-in-thick heavily -
: rooted zone at the ground surface _
1 2 5 -- — I
—�_—v
S1 9
t
5 `
0.40 I-,
--brown mottled rust,medium stiff to stiff, S-2 40__050
,•
.. ;ane-grained sand below 6 ft s 6.8 _11111_.. • Dry Density=90 pcf
I
Silty SAND,brown,medium dense,fine to medium 5-3
i '1 D•
Z. grained 7 ' t - •V8.0 ft(5/3/2017)
10- ycil-
°
;;
. ,, S-4 • _ � _ Dry Density=96 pd
� .
is 2 -13 1 —`
S-5 766 T •
I }
I '
1515.--,.:.....:;' --brown-gray,loose below 15 ft I
.--,.:.....:
S6 2 5 g
4
2..• _�. i 1
-'� I
20 : `. --very loose to loose at 20 ft I f
2 4 ■■
S-7 3 .
.:a 1
NI
Mlle _
-`-::.., i--- —
25---:•..•:t' S-8 22 5 - I I
4 I\ F111
o 3
f 1111
W —
H L_
H 30-:.•�.::;. -medium dense below 30 ft
o 5 -1 --
Fe S-9 1 s . li j
o s _____IVP_____.
_
W
W 1
o
z f
0 38-.?`;-..z. --dense at 35 ft;gray below 35 ft r 4 I
g S-10 �( 16 - -
1 17 --.'
O mooz
67
f.
m I.;
Fc
(CONTINUED NEXT PAGE) 0 0.5 1.0
Logged By: C.Jones Drilled by: Dan J.Fischer Excavating,Inc. • TORVANE SHEAR STRENGTH,TSF
Date Started: 5/3/17 Coordinates:Not Available III UNDRAINED SHEAR STRENGTH,TSF
Drilling Method: Solid-Stem Auger Hammer Type:Manual
Equipment: Buck Rogers 160 Trailer-Mounted Rig Weight:140 lb G Rii BORING B-1
Hole Diameter. 4 in. Drop:30 in.
Note:See Legend for Explanation of Symbols Energy Ratio:Not Available
JUNE 2017 JOB NO.5970-C FIG.1A
z' CLASSIFICATION OF MATERIAL o a ,- A BLOWS PER FOOT
o z ® MOISTURE CONTENT,
LL oZ w o 0 FINES CONTENT,%
= x = J 11---FLIQUID LIMIT,% COMMENTS AND
w W - ¢ ¢ 0 PLASTIC LIMIT,% ADDITIONAL TESTS
a Ca Surface Elevation: Not Available a ? co m m 0 50 100
Silty SAND,gray,medium dense,fine to medium 3 ■ L■■ n■■■■■■n
{'..; grained,interbedded with 2-in.-thick layer of sandy 1 t 16 IU I ■■■■■U%U
_ \silt at 41 ft r 41.5 ■■■■1//1111 n�
_ (5/3/2017) - I11 1MEM1 1■■u
11IIi:I!EIiiir■■nn ■■
45— �n� � .��■�� •i
_111110111111111111_11.1111011111111111
_ 111111.1111111111
_ olHioi
50-
:MMMMM
■
n■ ■ U-
_ H1111111011111-
111111111.111:1111
55_
"•IiIIIiII
60- ullIlil
'IF-i
11! U .IJOIIL
a 65-
iIiIiiP "
O
'IIiii
■ Ii
M- _w70_
> _1 Ill-j
1 U1
111110
Z 11111EMINVIMMI
75- I001" 'I
n■ ■ ■
o _ i■■■:�: Ci�i1'::
8 CLASSIFICATION OF MATERIAL o o -® BLOWS PER FOOT
z • MOISTURE CONTENT,%
u~- 0 L 3 z o 0 FINES CONTENT,%
F a F- a aa.. a. LIQUID LIMIT,% COMMENTS AND
w w - ¢ ¢ o0 PLASTIC LIMIT,% ADDITIONAL TESTS
0 o Surface Elevation: Not Available o __ ci w m 0 50 100
• Sandy SILT,brown,medium stiff,fine-to - ' 1 ` - ii l ' '
-, medium-grained sand,3-in.-thick heavily rooted ----
zone at ground surface I 1-:_1. - -
—i Ai - 0.40
- 11+0.45—f y'
•
S-1 41 --t _— Dry Density=83 pcf
---brown mottled rust,stiff below 4.5 ft 3 —10 /t ----
5
3-2 I 5 01
5 I
I
I
— t. Silty SAND,brown,medium dense,fine to medium 7.5S3 5 13 —
grained 9.. U 8 - ---
10— t; —loose below 10 ft 2 6 X10.0 ft(5/4/2017)
- ...._ 1 2 t v
6 _
_
--brown mottled rust at 12.5 ft 2 -�
. - 13 � I — 1
:;
15—....'•••• ', --very loose to loose at 15 ft
..
.: S.6
1 44 ----
3
20—r�iSr I i
1 \11,.` fS-7 3 • ® i _
5 i i
28 ''; .a -some silt to silty below 25 ft 2 8 _ —
--S-8 144 1 : "1"111111 i jiI
a ;
30-; .• , . --gray-brown,interbedded with 2-in:thick layers of p
silty sand below 30 ft s.9 4 (A► • -
1 3
> _
J
W 1
Z
o g5_. —
-LT
co FF
f
40
(CONTINUED NEXT PAGE) 0 0.5 1.0
Logged By: C.Jones Drilled by: Dan J.Fischer Excavating,Inc. • TORVANE SHEAR STRENGTH,TSF
Date Started: 5/4/17 Coordinates:Not Available ■ UNDRAINED SHEAR STRENGTH,TSF
Drilling Method: Solid-Stem Auger Hammer Type:Manual
Equipment: Buck Rogers 160 Trailer-Mounted Rig Weight:140 lb GR T B®n(A i�1 wnHole Diameter: 4 in. Drop:30 in. `i BORING L
Note:See Legend for Explanation of Symbols Energy Ratio:Not Available
JUNE 2017 JOB NO.5970-C FIG.2A
C.9 CLASSIFICATION OF MATERIAL ii z A BLOWS PER FOOT /°
°
F z r • MOISTURE CONTENT,
"- c� u u 0 0 FINES CONTENT,%
F- Q CL ii —L LIQUID LIMIT,% COMMENTS AND
w cd W z Q ¢ o PLASTIC LIMIT,% ADDITIONAL TESTS
o o Surface Elevation: Not Available o v, c.oM m ° 50 100
SAND,some silt to silty gray-brown,loose,fine to
s 1° 45 s
medium grained,interbedded with 2-in.-thick layers
\of silt r 41.5 4 ,
(5/4/2017) i -
45—
I
50— 1
55-
60-
1 1
5-60—
> > 1
1_,
_ I
65— , I — -
3 — II I —
r
a 70—
w -
J
° 75-
1I
0
m - _
EE
°-80
0 0.5 1.0
• TORVANE SHEAR STRENGTH,TSF
■ UNDRAINED SHEAR STRENGTH,TSF
GRI BORING B-2
JUNE 2017 JOB NO.5970-C FIG.2A
co CLASSIFICATION OF MATERIAL Z 1.1.1 F- A BLOWS PER FOOT
,_. '3 o o ck_ z 0 MOISTURE CONTENT,%
P
u j u j 0 0 FINES CONTENT,%
LIQUID LIMIT,% COMMENTS AND
ELLi- 1.... a a. a.
a. r,-,1- 2 M 0
LU - < < -4 PLASTIC LIMIT,% ADDITIONAL TESTS
ca o Surface Elevation: Not Available o c n cn co 0 50 100
..
Silty SAND,brown,medium dense,fine to medium —
::::',:.•• F
--,•:,i:., grained,3-in.-thick heavily rooted zone at the —
ground surface
..: —
.1.•:: ..: ffi. ____
_ Dry Density=92 pd
•::,....:•:. r
•:-::•,... s-i _ I 40 _,._
..,...... .i.._
5—.:• • • Sandy SILT,trace day,brown mottled rust,soft to S-2 22 4lik li
..... medium stiff,fine-to medium-grained sand 2 1
---.
-:• •• _ t.
,•..•
-- •
S-3
10-' :. --brown mottled rust stiff below 10 ft 2 12 10.0 ft(5/4/2017)
---n. •• --interbedded with 6-in.-thick layer of silty sand at
l 1ft
,
— I
—
—.. . 4 _10
S-5i
_... • I
,_
15 “. • 3
'....,;; Silty SAND,brown,medium dense,fine to medium 15.0 3
S-6 4 i
.--t1;*•,•':1•1
grained
a
:.-.•:.....
•:-::-.•.i
--:-.'::.• ':: i ,
•:.:"..::::•:, I , I
20 4.i:'*::- —loose below 20 ft I
:,..:•:E':. 2 5
-c:-'.-•':: 5-7 1 2
--1 1 i----.
••..:....:•:.
...`,:.,•:..-..
-i:-•.••,•1',.
l
r,--. 25.--c.'.;f::.: 111111.11 -
as ":,...:.: .... 2 5 -I
to ---z.:•:::'':2„ S-8 1 2 ._ L
1-- 1'.4.:*: '• 3 LEO 11
o In
TL117.. ,/.--::•::.-:
- 1 '
2 ::::: •::
ui
I .4 ---
30—c . •
rf
4 -I, 40' L-
...• --gray,medium dense below 30.5 ft
E2 -- '• ':
-•:.": .*.• 7
til -::*:-..:
I
ul
o --::,.•>':.: I
O 35_...t;:•,.••:;
li
O ,:.;':•:: _ I
-4 7E::•!:.::::..f.. ,I
Z I
co
(CONTINUED NEXT PAGE) 0 0.5 1.0
• TORVANE SHEAR STRENGTH,TSF
Logged By: C.Jones Drilled by: Dan J.Fischer Excavating,Inc.
II UNDRAINED SHEAR STRENGTH,TSF
Date Started: 5/4/17 I Coordinates:Not Available
Drilling Method: Solid-Stem Auger Hammer Type:Manual
Equipment: Buck Rogers 160 Trailer-Mounted Rig Weight:140 lb G REI
_ BORING B3
Hole Diameter: 4 in. Drop:30 in. -
Note:See Legend for Explanation of Symbols Energy Ratio:Not Available
JUNE 2017 JOB NO.5970-C FIG.3A
0 CLASSIFICATION OF MATERIAL zo a r A BLOWS PER FOOT
o — — o _ • MOISTURE CONTENT,
"- `� 'L 17.- w �, 0 0 FINES CONTENT,%
E F ¢ a a !---4—LIQUID LIMIT,% COMMENTS AND
ww m < ¢ o PLASTIC LIMIT,% ADDITIONAL TESTS
a o Surface Elevation: Not Available a z co co co 0 50 100
Silly SAND,brown mottled rust,medium dense to 4 IMMO 11111111111111=11101111111dense,fine to medium grained s-io1 10 ■■■ 7■■MM■■■■■■■■
41.5 20 ■■N■■■■
- (5/4(2017) MI ■
iiIiiiiIIiIIIIiiI
mum am
45— MUM ■ ■
_1IiI
11"11 ■■
50— 111 ■111111■■■■■
- — IC ®1
_ 1■ 11 1r ■
- I1111 11111111-
- 1111111
55— ■■H1■
iPEIIiiLiiiiIP1I-1
_
-
■■i1■■1■■■1■■ ■■■
60- ■■■■■■■■_■1111■ ■■■1
uiIIIIIiiii1 I1 11
65— ■■
ffif1ffIEI1jOI 0 -_
nipijililiw - �. 1■.'�:�IC, _
a 70— ■■■ ■ ■■ ■■■■ ■■
o ftI111; pjIII
> —
IIIiiIliEp::I1LW0 ■■ ■■■■■
- =1 .1111 '11"' •
■Bm'm
z
° 75— ■■■■■■■ ■ ■■
g - doiiijp:
-z - ■i■i■I0
�11O
R - ■■■ ■ ■■■■nln■ -
-8$ ■■■■■■■■■■■■■■■■■■
0 0.5 1.0
• TORVANE SHEAR STRENGTH,TSF
■ UNDRAINED SHEAR STRENGTH,TSF
GRIT BORING B-3
JUNE 2017 JOB NO.5970-C FIG.3A
SPT N60 SBT Tip COR Sleeve Stress F.Ratio Pore Pressure
(UNITLESS) (UNITLESS) (tsf) (tsf) (%) (psi)
0 0 250 0 12 0 500 0 14 0 12 -20 160
1 1 1 1 V20.*NM 1 1 1 1 1 1 1 1 1 V I I 1 1 1 1 1----4- 1 1 I 1 1 1 1 1 1 1
1
10 — — —
: 2
y�-m
15 — — —1
DIY,.
•
20 — — — —
Depth
(ft)
---<25 — • — — —
I
I
30 — —
—I
I ,
35 — — — — —I
7
r
rC
45
—
TOTAL DEPTH:42.323 ft
1 sensitive fine grained 4 silty clay to clay 7 silty sand to sandy silt 10 gravelly sand to sand
; 2 organic material 5 clayey silt to silty clay 8 sand to silty sand 11 very stiff fine grained(*)
3 clay 6 sandy silt to clayey silt 9 sand '12 sand to clayey sand(*)
RO
Observed By: N.Hatch Advanced By:Oregon Geotechnical Exploration,Inc.
Date Started: 05/4/17 Ground Surface Elevation: Not Available
Coordinates: Not Available CONE PENETRATION TEST CPT-1
JUNE 2017 JOB NO. 5970-C FIG. 4A
Seismic Velocity
(ft/s)
0 0 1400
I I I 1 I I
-- _—— 585
5 —
834
10 — s77
—696
15 —
-797
20 — 1330
Depth
(ft) siz
25 —
I
1104
30 — 723
874
35 —
770
40 —
45
TOTAL DEPTH:42.323 ft
Gip
Observed By: N.Hatch Advanced By:Oregon Geotechnical Exploration,Inc.
Date Started: 05/4/17 Ground Surface Elevation: Not Available CONE PENETRATION TEST CPT-1
Coordinates: Not Available
(SEISMIC VELOCITY PROFILE)
JUNE 2017 JOB NO. 5970-C FIG. 5A
SPT N60 SBT Tip COR Sleeve Stress F.Ratio Pore Pressure
(UNITLESS) (UNITLESS) (tsf) (tsf) (%) (psi)
0 0 180 0 12 0 200 0 12 0 12 -10 70
I I I I I I I I FIx] 1 I I I I I I I 1 I 1 1 1 I 1 1 1 I I I I I I 1 .----_,_4-=-1--- I1 I I I I I I
1
v
10 - w - - -
1
4
20 ,. - - -
1 \
TI
Depth
(ft) _
'CJ II
--5---.-
50 - - - -
r 4 I
uYS.„. kx-x�
^ a.r,..,a -
t,, ��� Ru
70 (..,_„, - - -
— - --_-_-__-_=-__ ?
80 I
TOTAL DEPTH:76.280 ft
1 sensitive fine grained 4 silty clay to clay 7 silty sand to sandy silt 10 gravelly sand to sand
2 organic material 5 clayey silt to silty clay 8 sand to silty sand 11 very stiff fine grained(")
3 clay 6 sandy silt to clayey silt 9 sand '1;12 sand to clayey sand(*)
GRO
Observed By: N.Hatch Advanced By:Oregon Geotechnical Exploration,Inc.
Date Started: 05/5/17 Ground Surface Elevation: Not Available CONE PENETRATION TEST CPT-2
Coordinates: Not Available
JUNE 2017 JOB NO. 5970-C FIG. 6A
SPT N60 SOT Tip COR Sleeve Stress F.Ratio Pore Pressure
(UNITLESS) (UNITLESS) (tsf) (tsf) (%) (psi)
0 0 250 0 12 0 300 0 12 0 12 -10 50
I 1 1 1 1 1 1 1 1 1 1 I I I I 1 I 1 1 I 1 I 1 I ) I 1 I 1
10 —
11\I
I
20 .,., — — —
2222 I
422,222
30 — — — — — I
I
Depthiii4i: I
(ft)
40 — ;z
I
50 —
I
1
60 — < —
I
1
I
I
70
TOTAL DEPTH: 66.929 ft
1 sensitive fine graine 4 silty clay to clay 7 silty sand to sandy si_ 10 gravelly sand to sand
2 organic material 5 clayey silt to silty c= 8 sand to silty sand 11 very stiff fine grained (*)
3 clay 6 sandy silt to clayey s 9 sand II 12 sand to clayey sand (*)
G 110
Observed By: N.Hatch Advanced By:Oregon Geotechnical Exploration,Inc.
Date Started: 05/5/17 Ground Surface Elevation: Not Available
Coordinates: NotAvailable CONE PENETRATIO\J TEST CPT-3
JUNE 2017 JOB NO. 5970-C FIG. 7A
Seismic Velocity
(ft/s)
0 1800
i i i i i i i i
748
939
10 — 724
1058
741
20 — 559
711
693
30 — 874
730
Depth
(ft)
1182
40 — 743
1713
613
50 — 1356
11240
- -_
70
TOTAL DEPTH:66.929 ft
G R 111
Observed By: N.Hatch Advanced By:Oregon Geotechnical Exploration,Inc.
Date Started: 05/5/17 Ground Surface Elevation: Not Available CONE PENETRATION TEST CPT-3
coordinates: Not Available
(SEISMIC VELOCITY PROFILE)
JUNE 2017 JOB NO. 5970-C FIG. 8A
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JUNE 2017 JOB NO. 5970-C FIG. 9A
APPENDIX C
Site-Specific Seisrnic-Hazard Evaluation
APPENDIX C
SITE-SPECIFIC SEISMIC-HAZARD STUDY
GENERAL
GRI completed a site-specific seismic-hazard study for the proposed improvements at Twality Middle
School in Tigard, Oregon. The purpose of our study was to evaluate the potential seismic hazards
associated with regional and local seismicity. The site-specific seismic-hazard evaluation is intended to
meet the requirements of the 2014 Oregon Structural Specialty Code (OSSC), which is based on the 2012
International Building Code (IBC). Seismic design in accordance with the 2012 IBC is based on American
Society of Civil Engineers (ASCE) document 7-10, titled "Minimum Design Loads for Buildings and Other
Structures." Our work was based on the potential for regional and local seismic activity, as described in
the existing scientific literature, and the subsurface conditions at the site, as disclosed by the subsurface
explorations completed for this project. Specifically, our work included the following tasks:
1) A detailed review of available literature, including published papers, maps, open-file
reports, seismic histories and catalogs, works in progress, and other sources of
information regarding the tectonic setting, regional and local geology, and historical
seismic activity that might have a significant effect on the site.
2) Compilation and evaluation of subsurface data collected at and in the vicinity of the
site, including classification and laboratory analyses of soil samples, and review of
shear-wave velocity surveys completed at the site. This information was used to
prepare a generalized subsurface profile for the site.
3) Identification of the potential seismic events (earthquakes) appropriate for the site and
characterization of those events in terms of a generalized design event.
4) Office studies based on the generalized subsurface profile and the generalized design
earthquake resulting in conclusions and recommendations concerning the following:
a) specific seismic events that might have a significant effect on the site,
b) the potential for seismic energy amplification and liquefaction or soil-strength loss
at the site, and
c) site-specific acceleration response spectra for design of the proposed structure.
This appendix describes the work accomplished and summarizes our conclusions and recommendations.
Geologic Setting
On a regional scale, the site is located at the northern end of the Willamette Valley, a broad, gently
deformed, north-south-trending topographic feature separating the Coast Range to the west from the
Cascade Mountains to the east. The site is located approximately 74 km inland from the Cascadia
Subduction Zone (CSZ), an active plate boundary along which remnants of the Farallon plate (the Gorda,
Juan de Fuca, and Explorer plates) are being subducted beneath the western edge of the North American
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plate. The subduction zone is a broad, eastward-dipping zone of contact between the upper portion of the
subducting slabs of the Gorda,Juan de Fuca, and Explorer plates and the overriding North American plate,
as shown on the Tectonic Setting Summary, Figure 1 C.
On a local scale, the site is located in the Tualatin Basin, a large, well-defined, southeast-trending structural
basin bounded by high-angle, northwest-trending, right-lateral, strike-slip faults considered to be
seismogenic. The geologic units in the area are shown on the Regional Geologic Map, Figure 2C. The
distribution of nearby Quaternary faults is shown on the Local Fault Map, Figure 3C. Information regarding
the continuity and potential activity of these faults is lacking due largely to the scale at which geologic
mapping in the area has been conducted and the presence of thick, relatively young, basin-filling
sediments that obscure underlying structural features. Other faults may be present within the basin, but
clear stratigraphic and/or geophysical evidence regarding their location and extent is not presently
available. Additional discussion regarding crustal faults is provided in the Local Crustal Event section
below.
Because of the proximity of the site to the CSZ and its location within the Tualatin Basin, three distinctly
different sources of seismic activity contribute to the potential for the occurrence of damaging earthquakes.
Each of these sources is generally considered to be capable of producing damaging earthquakes. Two of
these sources are associated with the deep-seated tectonic activity related to the subduction zone; the third
is associated with movement on the local, relatively shallow structures within and adjacent to the Tualatin
Basin.
Subsurface and Geologic Conditions. Published geologic mapping indicates the site is mantled with
Missoula flood deposits, locally referred to in the project area as the Willamette Silt Formation (Madin,
1990). In general, Willamette Silt is composed of unconsolidated beds and lenses of silt and sand.
Stratification within this formation commonly consists of 4-to 6-in.-thick beds, although in some areas, the
silt and sand are massive and the bedding is indistinct or nonexistent. Based on explorations completed in
the project vicinity, the Willamette Silt is underlain by Columbia River Basalt at depths of about 27.5 to 75
ft.
Seismicity
General. The geologic and seismologic information available for identifying the potential seismicity at the
site is incomplete, and large uncertainties are associated with estimates of the probable magnitude,
location, and frequency of occurrence of earthquakes that might affect the site. The available information
indicates the potential seismic sources that may affect the site can be grouped into three independent
categories: subduction zone events related to a sudden slip between the upper surface of the Juan de Fuca
plate and the lower surface of the North American plate, subcrustal events related to deformation and
volume changes within the subducted mass of the Juan de Fuca plate, and local crustal events associated
with movement on shallow, local faults within and adjacent to the Tualatin Basin. Based on our review of
currently available information, we have developed generalized design earthquakes for each of these
categories. The design earthquakes are characterized by three important properties: size, location relative
to the subject site, and the peak horizontal bedrock accelerations produced by the event. In this study,
earthquake size is expressed by the moment magnitude (Mw); location is expressed as the closest distance
to the fault rupture, measured in kilometers; and peak horizontal bedrock accelerations are expressed in
units of gravity (1 g = 32.2 ft/sect = 981 cm/sect).
GRUC-2
r Y +
Subduction Zone Event. The last interplate earthquake on the CSZ occurred in January 1700. Geological
studies show that great megathrust earthquakes have occurred repeatedly in the past 7,000 years (Atwater
et al., 1995; Clague, 1997; Goldfinger et al., 2003; and Kelsey et al., 2005), and geodetic studies
(Hyndman and Wang, 1995; Savage et al., 2000) indicate rate of strain accumulation consistent with the
assumption that the CSZ is locked beneath offshore northern California, Oregon, Washington, and
southern British Columbia (Fluck et al., 1997; Wang et al., 2001). Numerous geological and geophysical
studies suggest the CSZ may be segmented (Hughes and Carr, 1980; Weaver and Michaelson, 1985;
Guffanti and Weaver, 1988; Goldfinger, 1994; Kelsey and Bockheim, 1994; Mitchell et al., 1994;
Personius, 1995; Nelson and Personius, 1996; Witter, 1999), but the most recent studies suggest that for
the last great earthquake in 1700, most of the subduction zone ruptured in a single MW 9.0 earthquake
(Satake et al., 1996; Atwater and Hemphill-Haley, 1997; Clague et al., 2000). Published estimates of the
probable maximum size of subduction zone events range from moment magnitude Mw 8.3 to >9.0.
Numerous detailed studies of coastal subsidence, tsunamis, and turbidites yield a wide range of recurrence
intervals, but the most complete records (>4,000 years) indicate average intervals of 350 to 600 years
between great earthquakes on the CSZ (Adams, 1990; Atwater and Hemphill-Haley, 1997; Witter, 1999;
Clague et al., 2000; Kelsey et al., 2002; Kelsey et al., 2005; Witter et al., 2003). Tsunami inundation in
buried marshes along the Washington and Oregon coast and stratigraphic evidence from the Cascadia
margin support these recurrence intervals (Kelsey et al., 2005; Goldfinger et al., 2003).
The U.S. Geological Survey (USGS) probabilistic analysis assumes four potential locations of the eastern
edge of the earthquake rupture zone, shown on Figure 4C. The 2008 USGS mapping effort indicates three
rupture scenarios are assumed to represent these interface events: 1) Mw 9.0±0.2 events that rupture the
entire CSZ every 500 years, 2) Mw 8.3 to 8.7 events with rupture zones that occur on segments of the CSZ
and occur over the entire length of the CSZ during a period of about 500 years, and 3) Mw 8.0 to 8.2
events that rupture only segments of the CSZ every 500 years (Petersen et al., 2008). The assumed
distribution of earthquakes is shown on the Assumed Magnitude-Frequency Distribution, Figure 5C. This
distribution assumes the larger Mw 9.0 earthquakes likely occur more often than each of the smaller
segmented ruptures, as also indicated by the USGS deaggregation for the site. Therefore, for our
deterministic analysis, we have chosen to represent the subduction zone event by a design earthquake of
Mw 9.0 at a focal depth of 30 km and rupture distance of 74 km. This corresponds to a sudden rupture of
the whole length of the Juan de Fuca-North American plate interface with an assumed rupture zone due
west of the site. Based on an average of the attenuation relationships published by Atkinson and Macias
(2009), Zhao et al. (2006), and Abrahamson et al. (2015), a subduction zone earthquake of this size and
location would result in a peak horizontal bedrock acceleration of approximately 0.24 g at the site.
Subcrustal Event. There is no historical record of significant subcrustal, intraslab earthquakes in Oregon.
Although both the Puget Sound and northern California region have experienced many of these
earthquakes in historical times, Wong (2005) hypothesizes that due to subduction zone geometry,
geophysical conditions, and local geology, Oregon may not be subject to intraslab earthquakes. In the
Puget Sound area, these moderate to large earthquakes are deep (40 to 60 km) and over 200 km from the
deformation front of the subduction zone. Offshore along the northern California coast, the earthquakes
are shallower (up to 40 km) and located along the deformation front. Estimates of the probable size,
location, and frequency of subcrustal events in Oregon are generally based on comparisons of the CSZ
with active convergent plate margins in other parts of the world and on the historical seismic record for the
region surrounding Puget Sound, where significant events known to have occurred within the subducting
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Juan de Fuca plate have been recorded. Published estimates of the probable maximum size of these events
range from moment magnitude Mw 7.0 to 7.5. The 1949, 1965, and 2001 documented subcrustal
earthquakes in the Puget Sound area correspond to Mw 7.1, 6.5, and 6.8, respectively. Published
information regarding the location and geometry of the subducting zone indicates a focal depth of 50 km is
probable (Weaver and Shedlock, 1989). We have chosen to represent the subcrustal event by a design
earthquake of magnitude Mw 7.0 at a focal depth of 50 km and a rupture distance of 63 km. Based on the
attenuation relationships published by Youngs et al. (1997) and Abrahamson et al. (2015), a subcrustal
earthquake of this size and location would result in a peak horizontal bedrock acceleration of
approximately 0.17 g at the site.
Local Crustal Event. Sudden crustal movements along relatively shallow, local faults in the Portland area,
although rare, have been responsible for local crustal earthquakes. The precise relationship between
specific earthquakes and individual faults is not well understood since few of the faults in the area are
expressed at the ground surface and the foci of the observed earthquakes have not been located with
precision. The history of local seismic activity is commonly used as a basis for determining the size and
frequency to be expected of local crustal events. Although the historical record of local earthquakes is
relatively short(the earliest reported seismic event in the area occurred in 1920), it can serve as a guide for
estimating the potential for seismic activity in the area.
Based on fault mapping conducted by the USGS (Personius et al., 2003), the inferred location of the
Canby-Mollala Fault borders the southwest corner of the site. However, the USGS does not consider the
Canby-Mollala Fault to be an active, contributing source in their Probabilistic Seismic Hazard Analysis
(PSHA). Based on our review of the USGS deaggregations for the site (U.S. Geological Survey, 2014), the
Portland Hills Fault is the closest crustal fault contributing to the overall seismic hazard at the site. The
inferred location of the Portland Hills Fault is approximately 12 km from the site, and the fault has a
characteristic earthquake magnitude of Mw = 7. A crustal earthquake of this size would result in a peak
horizontal bedrock acceleration of approximately 0.42 g at the site based on an average of the next
generation attenuation (NGA) ground-motion relations published by Boore et al. (2014), Campbell and
Bozorgnia (2014), and Chiou and Youngs (2014).
Summary of Deterministic Earthquake Parameters
In summary, three distinctly different types of earthquakes affect seismicity in the project area.
Deterministic evaluation of the earthquake sources using recently published attenuation ground-motion
relations provides estimates of ground response for each individual earthquake type. Unlike probabilistic
estimates, these deterministic estimates are not associated with a relative hazard level or probability of
occurrence and simply provide an estimate of the ground-motion parameters for each type of fault at a
given distance from the site. The basic parameters of each type of earthquake are as follows:
Average
Earthquake Attenuation Relationships Rupture Focal Peak Bedrock Peak Bedrock
Source for Deterministic Spectra Magnitude,Mw Distance,km Depth,km Acceleration,g Acceleration,g
Subduction Zone Atkinson and Macias,2009 9.0 74.0 30 0.18
Zhao et al.,2006 9.0 74.0 30 0.23 0.24
Abrahamson et al.,2015 9.0 74.0 30 0.30
Subcrustal Youngs et al., 1997 7.0 63.0 50 0.10 0.17
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1 •
Average
Earthquake Attenuation Relationships Rupture Focal Peak Bedrock Peak Bedrock
Source for Deterministic Spectra Magnitude,MW Distance,km Depth,km Acceleration,g Acceleration,g
Abrahamson et al.,2015 7.0 63.0 50 0.24
Local Crustal Campbell and Bozorgnia,2014 7.0 12.0 NA 0.48
Chiou and Youngs,2014 7.0 12.0 NA 0.39 0.42
Boore et al. (2014) 7.0 12.0 NA 0.40
Probabilistic Considerations
The probability of an earthquake of a specific magnitude occurring at a given location is commonly
expressed by its return period, i.e., the average length of time between successive occurrences of an
earthquake of that size or larger at that location. The return period of a design earthquake is calculated
once a project design life and some measure of the acceptable risk that the design earthquake might occur
or be exceeded are specified. These expected earthquake recurrences are expressed as a probability of
exceedance during a given time period or design life. Historically, building codes have adopted an
acceptable risk level by identifying ground-acceleration values that meet or exceed a 10% probability of
exceedance in 50 years, which corresponds to an earthquake with an expected recurrence interval of 475
years. Previous versions of the IBC developed response spectra based on ground motions associated with
the Maximum Considered Earthquake (MCE), which is generally defined as a probabilistic earthquake with
a 2% probability of exceedance in 50 years (return period of about 2,500 years) except where subject to
deterministic limitations (Leyendecker and Frankel, 2000).
The recent 2012 IBC develops response spectra using a Risk-Targeted Maximum Considered Earthquake
(MCER), which is defined as the response spectrum expected to achieve a 1°/0 probability of building
collapse within a 50-year period. The design-level response spectrum is calculated as two-thirds of the
MCER ground motions. Since the MCER earthquake ground motions were developed by the USGS to
incorporate the targeted 1% in 50 years risk of structural collapse based on a generic structural fragility,
they are different than the ground motions associated with the traditional MCE. Although site response is
evaluated based on the MCER, it should be noted that seismic hazards, such as liquefaction and soil
strength loss, are evaluated using the Maximum Considered Earthquake Geometric Mean (MCEG) peak
ground acceleration (PGA), which is more consistent with the traditional MCE.
The 2012 IBC design methodology uses two mapped spectral acceleration parameters, Ss and Si,
corresponding to periods of 0.2 and 1.0 sec to develop the MCER earthquake. The Ss and Si parameters for
the site located at the approximate latitude and longitude coordinates of 45.4141°N and 122.7750°W are
0.96 and 0.42 g, respectively.
Estimated Site Response
The effect of a specific seismic event on the site is related to the type and quantity of seismic energy
delivered to the bedrock beneath the site by the earthquake and the type and thickness of soil overlying the
bedrock at the site. A ground-motion hazard analysis was completed to estimate this site-specific behavior
in accordance with Section 21.2 of ASCE 7-10. The ground-motion hazard analysis consisted of four
significant components: 1) estimation of bedrock response using recently developed attenuation
relationships (deterministic evaluation), 2) estimation of bedrock response using the 2014 USGS-based
PSHA (probabilistic evaluation), 3) comparison of the deterministic and probabilistic bedrock-response
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spectra to determine the controlling spectrum, and 4)development of recommended response spectra for
the four hazard levels. The following paragraphs describe the details of the ground-motion hazard analysis.
To estimate the deterministic bedrock-response spectrum, recently developed attenuation relationships
were used to evaluate bedrock ground motions at the site. Based on our review of the USGS
deaggregations (U.S. Geological Survey, 2014), crustal seismicity and an event on the CSZ represent the
largest contributing sources to the seismic hazard at the site. Considering this, we have chosen to estimate
the deterministic bedrock response using 84th-percentile ground motions from the following two
earthquake scenarios: 1) a Mw 7.0 crustal earthquake at a distance of 12 km from the site and 2) a Mw 9.0
subduction zone earthquake at a distance of 74 km from the site. The same attenuation relationships
outlined in the deterministic section were used to evaluate the crustal and subduction earthquake response.
The resulting deterministic bedrock-response spectra are shown on Figure 6C and indicate crustal
seismicity controls the hazard at the site. The deterministic MCER bedrock spectrum is taken as the larger
of the 84th-percentile ground motions and the deterministic lower limit. The probabilistic bedrock-
response spectrum was acquired through the use of the USGS Interactive Deaggregation (U.S. Geological
Survey, 2014). The deaggregation was evaluated for a 2% in 50 years probability over a period range of
PGA to 5 sec. In accordance with Section 21.2 of ASCE 7-10, the site-specific bedrock MCER response
spectrum is taken as the lesser of the probabilistic and deterministic MCER bedrock motions. Figure 6C
demonstrates the probabilistic bedrock spectrum is the lesser of the spectra.
The site is classified as Site Class D, or a stiff-soil site, based on the average Vs30 of 1,200 ft/sec in
accordance with Section 20.3 of ASCE 7-10. Corresponding short- and long-period adjustment factors Fa
and R of 1.12 and 1.58, respectively, were used to develop the probabilistic Site Class D MCER response
spectrum. We recommend using the Site Class D MCER and design response spectra shown on Figure 7C
for design of the new structure.
Seismic Hazards
Liquefaction/Cyclic Softening. The results of our evaluation indicate there is a potential that zones of the
interbedded sandy silt and silty sand deposit below the groundwater surface at the site could lose strength
or liquefy during a code-based earthquake. Based on our analysis, potentially liquefiable soils are present
below the groundwater level (10 ft) and extend to the top of basalt. Our analysis indicates the potential for
up to 1 in. of seismically induced settlement, which may occur during the earthquake and after earthquake
shaking has ceased.
Other Hazards. Based on site topography, the risk of earthquake-induced slope instability and/or lateral
spreading is low. The risk of damage by tsunami and/or seiche at the site is absent. The inferred location
of the Canby-Mollala Fault borders the southwest corner of the site (Personius et al., 2003); however, the
USGS does not consider the Canby-Mollala Fault to be an active, contributing source in their PSHA. The
USGS considers the Portland Hills Fault, located about 12 km northeast of the site, to be the closest crustal
fault source contributing to the overall seismic hazard at the site. Unless occurring on a previously
unmapped or unknown fault, the risk of fault rupture at the site is low.
CONCLUSIONS
The 2012 IBC design methodology uses two spectral response parameters, Ss and Si, corresponding to
periods of 0.2 and 1.0 sec to develop the MCER response spectrum. The Ss and Si parameters for the site
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are 0.96 and 0.42 g, respectively. The results of the ground-motion hazard analysis indicate the 2012 IBC
Site Class D spectrum provides an appropriate estimate of the spectral accelerations at the site. We
recommend use of the Site Class D design spectrum shown on Figure 7C for design of the new structure at
the site.
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Zhao,J.X.,Zhang,J.,Asano,A.,Ohno,Y.,Oouchi,T.,Takahashi,T.,Ogawa,H.,irikura,K.,Thio,H.,Somerville,P.,Fukushima,Y.,
and Fukushima,Y.,2006,Attenuation relations of strong ground motion in Japan using site classification based on
predominant period:Bulletin of the Seismological Society of America,vol.96,pp.898-913.
EREI
C-8
pm ., 130°‘;11'' ' 126' 122'W
Ce Q � t '`� 52°N PORTLAND
H��oi�\ NORTH AMERICA Coastline Coastal Cascades
(�o Q r PLATE I Range
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f /♦
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�d4a�C0 !I��NN'a C p d DISTANCE IN KM Crustal'faults
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a GORDA A LONGITUDE
S PLATE California
DEFORMATION B) EAST-WEST CROSS-SECTION THROUGH WESTERN OREGON AT THE LATITUDE OF PORTLAND,SHOWING THE SEISMIC
Mendocino Fault ,n 01
40 ' SOURCES CONSIDERED IN THE SITE-SPECIFIC SEISMIC HAZARD STUDY(MODIFIED FROM GEOMATRIX,19951
0 200 km
AI TECTONIC MAP OF PACIFIC NORTHWEST,SHOWING ORIENTATION AND EXTENT OF CASCADIA
SUBDUCTION ZONE IMODIFIED FROM DRAGERT AND OTHERS,19941
RO
TECTONIC SETTING SUMMARY
TUNE 2017 10B NO.5970-B FIG.1C
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z,.„,:.,: 4.Y'-•� / r„^," c;r;,k,,a.. 4 I iTm \ ----- ��.':/f \VJ `I '11 DT „,,-,;.;..,,,,,,,..,„e 1987,GEOLOGICMAP OF WASHINGTON-SOUTHWEST QUADRANT;I:250,000,
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WALKER,G.W.,AND MACLEOD,NS,1991,GEOLOGIC MAP OF OREGON:US.
-\,..A .....-0. T d 1 -y r V �' To j ,�� 11 to-1 G[OLOGK,IL SURVEY
- ,,.._ `- 1'-- 2,°.. `” ° E ,PP'. '-�J\--7`,-,' r Tbaat �� ! T 1`;.�A
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„.„,,......%� � T � rs \,, ��t ,.1 I J'i !";;3...P.Tti0 10 20 MILES
7.7---r �. r 1�,,,.',:h.1 I �` I 1QaI ,, To- v/�•V '1 S . ,r/�(1 sl„.--.1,4 Tio3 3 1 t
Ae) r -.' i-,----7,.\-A,,,'T _.�. ug,i T 1 I T Trb O9 0 10 20 KILOMETERS
,
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®®0
-t-? Fault—Dashed where inferred;dotted where concealed;queried where doubtful;ball and bar
on downthrown side
y?�.-. REGIONAL GEOLOGIC MAP
Thrust fault—Dashed where inferred;dotted where concealed;queried where doubtful;
sawteeth on upper plate
-LI Strike and dip of bed JUNE 2017 JOB NO.59708 HG.2C
__ --- ••� Kelso MAP EXPLANATION
' `\ TIME OF MOST RECENT SURFACE RUPTURE STRUCTURE TYPE AND RELATED FEATURES
—.. Holocene(<1,000 Years)or fit last glacial.(<15,000 yearn:15 Ya): -r- Normal or trigh.a gM reverse lawn
m.SIOUX n.1 _ Taoree m Oregon m -
dam a- Stan-An fawn
Gearhart 1
.. _..__._ Late Quaternary(n130.000;fest Penukima,0 0111.M1O) y- Throat Ian%
side _- Late and middle Oualorrery kat --
(n750,003 years:750 1- AmNirml foo
v - — Ouatanery,undlforentate0((1,800,000 Years;<l.0 Ma) -_I-- Synclinal told
— Cass a ett...1e(age N might.....n) -I- Merlon..told
t
t IP RATE
n— Plunge direction M ldd
Sob '..`a )� -..-•, ��SL>5 mmyeer a Faun se Won mark.
\.f 718 1050m nyear
— 0.2-1.0 mmyear DETAILED
As STUDY SESSLHelens I pa
— <0.2harcA SNe
mmyear
�.� . _ / 7 { J SuWoniwn ions NUtly SRe
DM 1 -}
TRACE
to r /!moi — Mostly CPnd uo set map scale
CULTURAL AND GEOGRAPHIC FEATURES
877 \ . / Av.Vancouver �", Monty UixonSnuars a map Orta. ----T Drvkler er sway
eco
tr ��\�580
, lniertad or Wrcaaletl Primary m secondary road
• _'�•""- „w,"'.•r-e"-'.. Permanent river or stream
ach ',.i.':•* ,®
Imamate.river or stream
Garibaldi
16';\-- 86 � Permanent or:ammeter,'lake
'�Bay City ,�•� '��` •'�� FAULT NUMBER NAME OF STRUCTURE
Forest Grove ' .",, 876
O 714 EAVERTOHELVETIA FAULT
882 \�8$1 _. i "> F�IllS�50Y0 875 Orr`.,. t$7$, 715 BEAVERTONFAULT
Tillamook 715 �'� . d d 879 86$L 866 71617 CANBV BERG F A FAULT
717 NEWBERG FAULT
718 • .4/4 1 718 GALES CREEK FAULT ZONE
.� - �+`�� ° Be pm 1 719 SALEM-EOIAHILLS HOMOCLINE
SIT $74�` 879 Portland • 864 CLACKAMAS RIVER FAULT ZONE
867 EAGLE CREEK THRUST FAULT
;717
868 BULL RUN THRUST FAULT
•
0AFea of MOUNT / 872 WALDO HILLS FAULT
1 Newberg Portland map HOOD873 MOUNT ANGEL FAULT
874
McMinnville FAULT
Canby';.• 875 OATFIEBOLTOtDN FAULT
Dayton '� 876 EAST BANK FAULT
Hubbard x'',716 877 PORTLAND HILLS FAULT
Woodburn 8(olalla 878 GRANT BUTTE FAULT
Sheridan -= 879 DAMASCUS-TICKLE CREEK FAULT ZONE
:Amity •` 880 LACAMAS LAKE FAULT
881 TILLAMOOK BAY FAULT ZONE
Silverton s-2.873
/ ! (` FROM: PERSONIUS,S.F.,AND OTHERS,2603,MAP OF QUATERNARY FAULTS AND
�+ FOLDS IN OREGON,USGS OPEN FILE REPORT OFR-03045.
719 Salem
Dallas ,
1. .'
independence i A 872 . 864 -1
884 -Manmouttr �7r\; _ _( I 0 10 20 MILES
n T 871 Stayton 8
� X
,'•1 Y719 _.. wl 9 20 40(KICOMET RS
44 k, Mill City
IMMO
LOCAL FAULT MAP
)UNE 2017 LOB NO.5970-B FIG.3C
•
r
�.,-, �.
b
r,S %�i
Y
- �,_-..,,,e,-, *4
sSr.N, .., 'd:s
-� " , FIGURE 21. LOCATION OF THE EASTERN EDGE Of EARTHQUAKE RUP-
f TURF ZONES ON THE CASCADIA SUBDUCTION ZONE FOR THE VARIOUS
MODELS USED IN THIS STUDY RELATIVE TO THE SURFICIAL EXPRESSION
€ OF THE TRENCH:TOP,BASE Of THE ELASTICRT ZONE;MID,MIDPOINT OF
44°N ,f? "' THE TRANSITION ZONE;BOTTOM,BASE OFI HE TRANSITION ZONES;
BASE,BASE OF THE MODEL THAT ASSUMES UPTURES EXTEND TO
ABOUT 30-KILOMETERS DEPTH.FIGURE PROVIDED BY RAY WELDON.
, ==,/,..74',14,!,4,2,,,4
7 1;1144,
,14` '€,4-
r
#' vy i: :.� < �aa t--.42°N Il
,J 4,.! top
i4, .s mrd
Y ' bottom „
--� '17�-' ,L base
.... trench
126°W 124°W 122°W
FROM: PETERSEN,MD,FRANKEL,AD,HARMSEN,SC, AND OTHERS,2008,DOCUMENTATION
FOR THE 2008 UPDATE OF THE UNITED STATES NATIONAL SEISMIC HAZARD MAPS:US
GEOLOGICAL SURVEY,OPEN FILE REPORT 2008-1128
G R 0
ASSUMED RUPTURE LOCATIONS
(CASCADIA SUBDUCTION ZONE)
JUNE 2017 JOB NO. 5970-B FIG. 4C
,
0.0009 -
0.0008
0.0007 ,
/111\ .U..1
Y
a
a 0.0006
e
a
LU
u, 0.0005 .
w
I--
<
C
Q 0.0004
z .
Q ."
0.0003
0.0002 =
0.0001
0
7.8 8 8.2 8.4 8.6 8.8 9 9.2 9.4
MOMENT MAGNITUDE
Figure 22. Magnitude-frequency distribution of the Cascadia subduction zone.
FROM: PETERSEN,M,FRANKEL,A,HARMSEN,S, AND OTHERS,2008,DOCUMENTATION
FOR THE 2008 UPDATE OF THE UNITED STATES NATIONAL SEISMIC HAZARD MAPS:US
GEOLOGICAL SURVEY,OPEN FILE REPORT 2008-1128
G RO
ASSUMED
MAGNITUDE-FREQUENCY DISTRIBUTION
(CASCADIA SUBDUCTION ZONE)
JUNE 2017 JOB NO. 5970-B FIG. 5C
.
2.2
Deterministic Bedrock Response Spectrum
Based on Portland Hills Fault Hazard
2.0 (84th Percentile Ground Motions)
1.8 I
Deterministic Lower Limit Response Spectrum
1.6 I
1.4 Probabilistic Bedrock Response Spectrum
Based on 2% in 50-Year Hazard
c ' (USGS 2014 Deaggregation)
i 1.2
a
a
Rs 1.0
Deterministic Bedrock Response Spectrum
\ Based on Subduction Zone Hazard
(84th Percentile Ground Motions)
N \
0.6 \
0.4 —
0.2 —
0.0 J I I I
0 1 2 3 4
Period,T,seconds
G RD
DETERMINISTIC VS PROBABILISTIC
BEDROCK RESPONSE SPECTRA
(5%DAMPING)
JUNE 2017 JOB NO. 5970-B FIG. 6C
•
,
1.2
1.0
0.8
nn
Recommended MCER Response Spectrum
u 0.6
Q
b
U
4J
Recommended Design Response Spectrum
0.4
0.2
0.0 I I I
0 1 2 3 4
Period, T, seconds
G RO
DESIGN AND RECOMMENDED
MCER RESPONSE SPECTRA
(5°/0 DAMPING)
JUNE 2017 JOB NO. 5970-B FIG. 7C