Report ro pp -0 9- croI
.. GeoPi
Engineer ng; lite ?t
Real -World Geotechnical Solutions
Investigation • Design • Construction Support
August 26, 2009
Project No: 09 -1831
Eric Evans
Emerio Design
■1 6107 SW Murray Boulevard, Suite 147
Beaverton, Oregon 97008
Via e-mail with hard copies mailed
[1 Subject: Geotechnical Engineering Report
Commercial Building Improvements and Driveway
7900 SW Hunziker Street
J Tigard, Oregon
At your request, GeoPacific Engineering, Inc. (GeoPacific) performed a geotechnical engineering study for
the proposed building and driveway improvements located at 7900 SW Hunziker Street in Tigard, Oregon.
The purpose of this study was to evaluate subsurface conditions at the site and to provide geotechnical
recommendations for site development. This geotechnical study was performed in accordance with
GeoPacific Proposal No. P -3644, dated August 5, 2009, and your subsequent authorization of our proposal
and General Conditions for Geotechnical Services.
SITE DESCRIPTION AND PROPOSED DEVELOPMENT
The site is located at 7900 SW Hunziker Street in the City of Tigard, Oregon (Figures 1 and 2). The property
is currently occupied by an existing building and parking lot. Development plans include construction of a
concrete slab foundation for a new tank and other equipment. An additional driveway along the southeastern
portion of the building will be constructed. This driveway will be used primarily by heavy fuel tanker trucks,
estimated to be on site about once per week. A grading plan for the project has not yet been completed;
however, we anticipate grading will be minimal.
REGIONAL GEOLOGIC SETTING
Regionally, the subject site lies within the Willamette Valley /Puget Sound lowland, a broad structural
depression situated between the Coast Range on the west and the Cascade Range on the east. .A series of
discontinuous faults subdivide the Willamette Valley into a mosaic of fault- bounded, structural blocks (Yeats
et al., 1996). Uplifted structural blocks form bedrock highlands, while down - warped structural blocks form
sedimentary basins.
The subject site is underlain by the Quaternary age (last 1.6 million years) Willamette Formation, a
catastrophic flood deposit associated with repeated glacial outburst flooding of the Willamette Valley river
system (Madin, 1990). These deposits consist of horizontally layered, micaceous, fine silt to coarse sand
forming poorly - defined to distinct beds less than 3 feet thick. Underlying the Willamette Formation is
Miocene aged (about 14.5 to 16.5 million years ago) Columbia River Basalt, a thick sequence of lava flows
which forms the basement of the basin.
13910 SW Galbreath Drive, Suite 102 Tel (503) 625 -4455
Sherwood, Oregon 97140 Fax (503) 625 -4405
August 26, 2009
GeoPacific Project No. 09 -183
At least three major source zones capable of generating damaging earthquakes are thought to exist in the
vicinity of the subject site. These include the Gales Creek - Newberg -Mt. Angel Structural Zone, the Portland
Hills Fault Zone, and the Cascadia Subduction Zone.
Portland Hills Fault Zone
The Portland Hills Fault Zone is a series of NW-trending faults that include the central Portland Hills Fault, the
western Oatfield Fault, and the eastern East Bank Fault. These faults occur in a northwest- trending zone that
varies in width between 3.5 and 5.0 miles. The combined three faults vertically displace the Columbia River
Basalt by 1,130 feet and appear to control thickness changes in late Pleistocene (approx. 780,000 years)
sediment (Madin, 1990). The Portland Hills Fault occurs along the Willamette River at the base of the
Portland Hills, and is about 6 miles northeast of the site. The Oatfield Fault occurs along the western side of
the Portland Hills, and is about 4 miles northeast of the site. The accuracy of the fault mapping is stated to be
within 500 meters (Wong, et al., 2000). No historical seismicity is correlated with the mapped portion of the
Portland Hills Fault Zone, but in 1991 a M3.5 earthquake occurred on a NW- trending shear plane located 1.3
miles east of the fault (Yelin, 1992). Although there is no definitive evidence of recent activity, the Portland
Hills Fault Zone is assumed to be potentially active (Geomatrix Consultants, 1995).
Gales Creek - Newberg -Mt. Angel Structural Zone
The Gales Creek - Newberg -Mt. Angel Structural Zone is a 50- mile -long zone of discontinuous, NW- trending
faults that lies about 14.5 miles southwest of the subject site. These faults are recognized in the subsurface by
vertical separation of the Columbia River Basalt and offset seismic reflectors in the overlying basin sediment
(Yeats et al., 1996; Werner et al., 1992). A geologic reconnaissance and photogeologic analysis study
conducted for the Scoggins Dam site in the Tualatin Basin revealed no evidence of deformed geomorphic
surfaces along the structural zone (Unruh et al., 1994). No seismicity has been recorded on the Gales Creek or
Newberg Fault (the fault closest to the subject site); however, these faults are considered to be potentially
active because they may connect with the seismically active Mount Angel Fault and the rupture plane of the
1993 M5.6 Scotts Mills earthquake (Werner et al. 1992; Geomatrix Consultants, 1995).
Cascadia Subduction Zone
The Cascadia Subduction Zone is a 680 - mile -long zone of active tectonic convergence where oceanic crust
of the Juan de Fuca Plate is subducting beneath the North American continent at a rate of 4 cm per year
(Goldfinger et al., 1996). A growing body of geologic evidence suggests that prehistoric subduction zone
earthquakes have occurred (Atwater, 1992; Carver, 1992; Peterson et al., 1993; Geomatrix Consultants,
1995). This evidence includes: (1) buried tidal marshes recording episodic, sudden subsidence along the
coast of northern California, Oregon, and Washington, (2) burial of subsided tidal marshes by tsunami wave
deposits, (3) paleoliquefaction features, and (4) geodetic uplift patterns on the Oregon coast. Radiocarbon
dates on buried tidal marshes indicate a recurrence interval for major subduction zone earthquakes of 250 to
650 years with the last event occurring 300 years ago (Atwater, 1992; Carver, 1992; Peterson et al., 1993;
Geomatrix Consultants, 1995). The inferred seismogenic portion of the plate interface lies roughly along the
Oregon Coast at depths of 20 and 40 kilometers below the ocean surface.
FIELD EXPLORATION AND LABORATORY TESTING
The site - specific exploration for this study was conducted on August 11, 2009. Three exploratory borings
(designated B -1 through B -3) were drilled to depths of 0.8 to 7.5 feet, at the approximate locations shown on
Figure 2. It should be noted that boring locations were determined in the field by pacing or taping distances
from apparent property corners and other site features shown on the plans provided. As such, the locations
of the explorations should be considered approximate.
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GeoPacific Project No. 09 -1831
The boreholes were drilled using a trailer- mounted drill rig and solid stem auger methods. At boring B -1,
{ SPT (Standard Penetration Test) sampling was performed in general accordance with ASTM D1586 using a
2 -inch outside diameter split -spoon sampler and a 140 -pound hammer equipped with a rope and cathead
mechanism. During the test, a sample is obtained by driving the sampler 18 inches into the soil with the
hammer free - falling 30 inches. The number of blows for each 6 inches of penetration is recorded. The
J
Standard Penetration Resistance ( "N- value ") of the soil is calculated as the number of blows required for the
final 12 inches of penetration. If 50 or more blows are recorded within a single 6 -inch interval, the test is
terminated, and the blow count is recorded as 50 blows for the number of inches driven. This resistance, or
N- value, provides a measure of the relative density of granular soils and the relative consistency of cohesive
soils. At the completion of the borings, the holes were backfilled with bentonite.
Explorations were conducted under the full -time observation of GeoPacific personnel. Soil samples obtained
from the boring were classified in the field and representative portions were placed in relatively air -tight
plastic bags. These soil samples were then returned to the laboratory for further examination and laboratory
testing. Pertinent information including soil sample depths, stratigraphy, soil engineering characteristics, and
groundwater occurrence was recorded. Soils were classified in general accordance with the Unified Soil
Classification System.
Summary borehole logs are attached. The stratigraphic contacts shown on the individual borehole logs
represent the approximate boundaries between soil types. The actual transitions may be more gradual. The
soil and groundwater conditions depicted are only for the specific dates and locations reported, and therefore,
are not necessarily representative of other locations and times.
Pavement Dynamic Cone Penetrometer Testing
On August 11, 2009, two Pavement Dynamic Cone Penetrometer (PDCP) tests were conducted to determine
the strength parameters of the native soil for support of pavement. Correlated California Bearing Ratio
(CBR) value at the test location is indicated on Table 1.
Table 1. PDCP Field Test and Correlated CBR
Depth Interval Average Correlated
Location Material Tested (feet) Penetration Per CBR
B Blow (mm)
B -2 SILT 0.9 — 2.3 33 7
B -3 SILT 1.2 — 2.5 26 10
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GeoPacific Project No. 09 -1831
Existing Pavement Section
On August 11, 2009, three cores were conducted in the existing pavement to determine the thickness of the
!J asphalt and underlying crushed rock. The results of the pavement cores are indicated in Table 2.
Table 2. Existing Pavement Section
i
Location Asphaltic Crushed Aggregate Subgrade
Concrete (AC) Base % " -0
1 B -1 2.5 Inches 5.5 Inches 8 Inches Undocumented Fill
(SILT) underlain by native SILT
{ B -2 2.5 Inches 4 Inches Native SILT
ri
Undocumented Fill (SILT)
B -3 2.5 Inches 5 Inches underlain by native SILT
SUBSURFACE CONDITIONS
The following discussion is a summary of subsurface conditions encountered in our explorations. For more
detailed information regarding subsurface conditions at specific exploration locations, refer to the attached
test pit logs. Also, please note that subsurface conditions can vary between exploration locations, as
discussed in the Uncertainty and Limitations section below.
11 Soils
On -site soils consist of undocumented fill and the Willamette Formation as described below.
Undocumented Fill — Underlying the existing pavement section in borings B -1 and B -3 was undocumented
fill. These soils generally consisted of medium stiff, gray silt. The fill extended to a depth of 1.3 feet in
boring B -1 and beyond the depth of exploration in boring B -3.
Willamette Formation — Underlying the undocumented fill in borings B -1 and B -3 and the existing
pavement in boring B -2 were soils belonging to the Willamette Formation. These soils generally consisted
of medium stiff to stiff, sandy silt with subtle orange and gray mottling. Soils of the Willamette Formation
extended beyond the maximum depth of exploration (6.5 feet).
Groundwater
Groundwater was not encountered during our explorations to a depth of 6.5 feet below ground surface. It is
anticipated that groundwater conditions will vary depending on the season, local subsurface conditions,
changes in site utilization, and other factors. Perched groundwater conditions often occur over fine- grained
native deposits and engineered fill such as those beneath the site, particularly during the wet season
CONCLUSIONS AND RECOMMENDATIONS
Results of this study indicate that the proposed development is geotechnically feasible, provided that the
recommendations of this report are incorporated into the design and construction phases of the project. The
proposed concrete slab foundation for the new holding tank may be supported on competent undisturbed
native soils, or engineered fill, designed and constructed as recommended in this report. Recommendations
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August 26, 2009
GeoPacific Project No. 09 -1831
are presented below for structural foundations, wet weather earthwork, excavation conditions and utility
trenches, pavement section, and erosion control considerations.
Concrete Slab - on - grade Structural Foundations
Based on our understanding of the proposed project and the results of our exploration program, and assuming
our recommendations for site preparation are followed, medium stiff to stiff native deposits and/or
engineered fill soils will be encountered at or near the foundation level of the proposed structures. To
provide adequate foundation support, we recommend a minimum of 6 inches of compacted 3 /4" -0 crushed
rock be placed below the bottom of the concrete slab. Crushed rock placed beneath the slab should be
compacted to a minimum of 90 percent of Modified Proctor (ASTM D1557) or equivalent.
We recommend a maximum allowable bearing pressure of 2,500 pounds per square foot (psf) for designing
the slab. The recommended maximum allowable bearing pressure may be increased by a factor of 1.33 for
short term transient conditions such as wind and seismic loading. For evaluation of the concrete slab-on-
: grade foundations using the beam on elastic foundation method, a modulus of subgrade reaction of 200 kcf
(115 pci) should be assumed for the stiff native silt soils anticipated at foundation depth. This value assumes
the concrete slab system is designed and constructed as recommended herein, with a minimum thickness of
crushed rock of 6 inches beneath the slab.
Assuming construction is accomplished as recommended herein, and for the foundation loads anticipated, we
estimate total settlement of spread foundations of less than about 1 inch and differential settlement between
two adjacent load - bearing components . supported on competent soil of less than about 1/2 inch. We anticipate
that the majority of the estimated settlement will occur during construction, as loads are applied.
Wind, earthquakes, and unbalanced earth loads will subject the proposed structure to lateral forces. Lateral
forces on a structure will be resisted by a combination of sliding resistance of its base or footing on the
underlying soil and passive earth pressure against the buried portions of the structure. For use in design, a
coefficient of friction of 0.5 may be assumed along the interface between the base of the footing and
subgrade soils. Passive earth pressure for buried portions of structures may be calculated using an equivalent
fluid weight of 390 pounds per cubic foot (pcf), assuming footings are cast against dense, natural soils or
engineered fill. The recommended coefficient of friction and passive earth pressure values do not include a
safety factor. The upper 12 inches of soil should be neglected in passive pressure computations unless it is
protected by pavement or slabs on grade.
Preparation of areas beneath concrete slab -on -grade foundations should be performed as recommended in the
Site Preparation section. Care should be taken during excavation to avoid disturbing subgrade soils.
Footing excavations should be trimmed neat and the bottom of the excavation should be carefully prepared.
Loose, wet or otherwise softened soil should be removed from the footing excavation prior to placing
crushed rock. If subgrade soils have been adversely impacted by wet weather or otherwise disturbed, the
surficial soils should be scarified to a minimum depth of 8 inches, moisture conditioned to within about 3
percent of optimum moisture content, and compacted to engineered fill specifications. Alternatively,
disturbed soils may be removed and the removal zone backfilled with additional crushed rock. GeoPacific
should observe foundation excavations prior to placement of crushed rock and should test the compaction of
the crushed rock prior to placing reinforcing steel and formwork, to verify that an appropriate bearing
stratum has been encountered and that soils are suitable to support the planned loads.
The above foundation recommendations are for dry weather conditions. Due to the high moisture sensitivity
of engineered fill and native soils, construction during wet weather is likely to require overexcavation of
footings and backfill with additional compacted, crushed aggregate. As a result of this condition, we
recommend foundation excavations be observed to verify subgrade strength.
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GeoPacific Project No. 09 -1831
Seismic Design
E j Structures should be designed to resist earthquake loading in accordance with the methodology described in
the 2006 International Building Code (IBC) with applicable 2007 Oregon Structural Specialty Code (OSSC)
revisions. We recommend Site Class D be used for design per the OSSC, Table 1613.5.2. Design values
determined for the site using the USGS (United States Geological Survey) Earthquake Ground Motion
1i Parameters utility are summarized below.
Table 3. Recommended Earthquake Ground Motion Parameters (2006 IBC / 2007 OSSC)
Parameter Value
Location (Lat, Long), degrees 45.424, - 122.761
Mapped Spectral Acceleration Values
(MCE, Site Class D):
Short Period, S, 0.941 g
1.0 Sec Period, S 0.338 g
Soil Factors for Site Class D:
ii Fa 1.123
F 1.724
SD = 2/3 x F x S 0.705 g
SD, = 2/3 x F, x S 0.389 g
Potential seismic impacts also include secondary effects such as soil liquefaction, fault rupture potential, and
other hazards as discussed below:
• Soil Liquefaction Potential — Soil liquefaction is a phenomenon wherein saturated soil deposits
temporarily lose strength and behave as a liquid in response to earthquake shaking. Soil
liquefaction is generally limited to loose, granular soils located below the water table. On -site
soils consist of medium stiff to stiff native silts that are considered to have a low potential for
liquefaction. Therefore, it is our opinion that no special design or construction measures are
needed to mitigate the effects of liquefaction.
• Fault Rupture Potential — Based on our review of available geologic literature, we are not
aware of any mapped active (demonstrating movement in the last 10,000 years) faults on the site.
During our field investigation, we did not observe any evidence of surface rupture or recent
faulting. Therefore, we conclude that the potential for fault rupture on site is very low.
• Effects of Local Geology and Topography — In our opinion, no additional seismic hazard will
occur due to local geology or topography. The site is expected to have no greater seismic hazard
than surrounding properties and the Tigard area in general.
Wet Weather Earthwork
The on -site soils are moisture sensitive and may be difficult to handle or traverse with construction
equipment during periods of wet weather. Earthwork is typically most economical when performed under
dry weather conditions. Earthwork performed during the wet - weather season will probably require
expensive measures such as cement treatment or imported granular material to compact fill to the
recommended engineering specifications. If earthwork is to be performed or fill is to be placed in wet
weather or under wet conditions when soil moisture content is difficult to control, the following
recommendations should be incorporated into the contract specifications.
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D Earthwork should be performed in small areas to minimize exposure to wet weather. Excavation or the
removal of unsuitable soils should be followed promptly by the placement and compaction of clean
engineered fill. The size and type of construction equipment used may have to be limited to prevent soil
disturbance. Under some circumstances, it may be necessary to excavate soils with a backhoe to
111 minimize subgrade disturbance caused by equipment traffic;
D The ground surface within the construction area should be graded to promote run -off of surface water
and to prevent the ponding of water;
> Material used as engineered fill should consist of clean, granular soil containing less than 5 percent fines.
The fines should be non - plastic. Alternatively, cement treatment of on -site soils may be performed to
facilitate wet weather placement;
D The ground surface within the construction area should be sealed by a smooth drum vibratory roller, or
equivalent, and under no circumstances should be left uncompacted and exposed to moisture. Soils
which become too wet for compaction should be removed and replaced with clean granular materials;
D Excavation and placement of fill should be observed by the geotechnical engineer to verify that all
unsuitable materials are removed and suitable compaction and site drainage is achieved; and
D Bales of straw and/or geotextile silt fences should be strategically located to control erosion.
If cement or lime treatment is used to facilitate wet weather construction, GeoPacific should be contacted to
provide additional recommendations and field monitoring.
Excavating Conditions and Utility Trenches
We anticipate that on -site soils can be excavated to depths anticipated for this project (up to 6.5 feet) using
conventional heavy equipment such as scrapers and trackhoes. Maintenance of safe working conditions,
including temporary excavation stability, is the responsibility of the contractor. Actual slope inclinations at
the time of construction should be determined based on safety requirements and actual soil and groundwater
conditions. All temporary cuts in excess of 4 feet in height should be sloped in accordance with U.S.
Occupational Safety and Heath Administration (OSHA) regulations (29 CFR Part 1926), or be shored. The
existing native soils classify as Type B Soil and temporary excavation side slope inclinations as steep as
1H: 1 V may be assumed for planning purposes. This cut slope inclination is applicable to excavations above
the water table only.
Perched oundwater is likely to be encountered during the wet weather season and should be anticipated in
i� Y g P
excavations and utility trenches. The contractor should be prepared to implement an appropriate dewatering
system for installation of the utilities. At this time, we anticipate that dewatering systems consisting of
ditches, sumps and pumps would be adequate for control of groundwater where encountered during
construction conducted during the dry season. Regardless of the dewatering system used, it should be
installed and operated such that in -place soils are prevented from being removed along with the groundwater.
Vibrations created by traffic and construction equipment may cause some caving and raveling of excavation
walls. In such an event, lateral support for the excavation walls should be provided by the contractor to
prevent loss of ground support and possible distress to existing or previously constructed structural
improvements.
PVC pipe should be installed in accordance with the procedures specified in ASTM D2321. We recommend
that structural trench backfill be compacted to at least 95 percent of the maximum dry density obtained by
Standard Proctor (ASTM D698) or equivalent. Initial backfill lift thick nesses for a' / < " -0 crushed aggregate
base may need to be as great as 4 feet to reduce the risk of flattening underlying flexible pipe. Subsequent
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GeoPacific Project No. 09 -1831
lift thickness should not exceed 1 foot. If imported granular fill material is used, then the lifts for large
vibrating plate- compaction equipment (e.g. hoe compactor attachments) may be up to 2 feet, provided that
proper compaction is being achieved and each lift is tested. Use of large vibrating compaction equipment
should be carefully monitored near existing structures and improvements due to the potential for vibration -
induced damage.
i Adequate density testing should be performed during construction to verify that the recommended relative
compaction is achieved. Typically, at least one density test is taken for every 4 vertical feet of backfill on
each 200 - lineal -foot section of trench.
R
Pavement Sections
The existing pavement surface is in poor condition, with "alligator" cracking which is an indication of
inadequate pavement section and possible subgrade soil failure. Attempting to overlay existing pavements
that exhibit alligator cracking most often results in reflective cracking which damages the new pavement
overlay after a few years of use. For this reason we do not recommend overlaying the existing pavement.
Recommendations for a long -term pavement solution are presented below. In our opinion, these
recommendations do not need to be implemented immediately. The existing pavement surface could be used
for a time, although it should be noted there is some potential for rutting and failure of subgrade soils under
heavy truck loading, particularly during the wet season. We suggest that during construction, the surface of
the existing pavement be proof - rolled with a loaded dump truck to verify the ability of the existing pavement
section to support heavy truck traffic.
L
Table 4 presents recommended minimum pavement sections for dry- weather construction conditions. The
11 truck driveway section is based on the assumed loaded fuel tanker truck / trailer combination, accessing the
site once or twice per week.
l R Table 4. Recommended Minimum Dry- Weather Pavement Section
Ii
Layer Thickness (inches)
Material Layer Automobile Compaction Standard
Truck Driveway Drives /
Parking
Asphaltic Concrete (AC) 3 2.5 91% of Rice Density
AASHTO T -209
Crushed Aggregate Base' /4 " -0 95% of Modified Proctor
(leveling course) 2 2 ASTM D1557
Crushed Aggregate Base 1' /z " -0 10 8 95% of Modified Proctor
ASTM D1557
Recommended Subgrade 12 12 95% of Standard Proctor
or approved native
Following removal of the existing pavement section materials, native soil subgrade in pavement areas should
be ripped or tilled to a minimum depth of 12 inches, moisture conditioned, and recompacted in -place to at
least 95 percent of ASTM D698 (Standard Proctor) or equivalent. In order to verify subgrade strength, we
recommend proof - rolling directly on subgrade with a loaded dump truck during dry weather and on top of
base course in wet weather. Soft areas that pump, rut, or weave should be stabilized prior to paving. If
pavement areas are to be constructed during wet weather, GeoPacific should review subgrade at the time of
construction so that condition specific recommendations can be provided. Wet - weather pavement
construction is likely to require soil amendment, or geotextile fabric and an increase in base course thickness.
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During placement of pavement section materials, density testing should be performed to verify compliance
with project specifications. Generally, one subgrade, one base course, and one AC compaction test is
performed for every 100 to 200 linear feet of paving.
The pavement sections recommended in Table 4 are for typical volumes of automobile traffic, and the truck
traffic indicated. Increased heavy truck traffic will reduce the design life of the pavements and may lead to
inadequate pavement performance. In addition, heavy trucks making tight turns on asphaltic pavements can
also reduce pavement life. If truck traffic greater than that assumed herein is anticipated, GeoPacific should
be contacted for additional pavement design recommendations based on the traffic volumes expected.
Erosion Control Considerations
During our field exploration program, we did not observe soil types that would be considered highly
susceptible to erosion. In our opinion, the primary concern regarding erosion potential will occur during
construction, in areas that have been stripped of vegetation. Erosion at the site during construction can be
minimized by implementing the project erosion control plan, which should include judicious use of straw
bales and silt fences. If used, these erosion control devices should be in place and remain in place throughout
site preparation and construction.
fj
l Erosion and sedimentation of exposed soils can also be minimized by quickly re- vegetating exposed areas of
soil, and by staging construction such that large areas of the project site are not denuded and exposed at the
same time. Areas of exposed soil requiring immediate and/or temporary protection against exposure should
be covered with either mulch or erosion control netting/blankets. Areas of exposed soil requiring permanent
stabilization should be seeded with an approved grass seed mixture, or hydroseeded with an approved seed -
mulch - fertilizer mixture.
l
UNCERTAINTIES AND LIMITATIONS
We have prepared this report for the owner and their consultants for use in design of this project only. This
report should be provided in its entirety to prospective contractors for bidding and estimating purposes;
however, the conclusions and interpretations presented in this report should not be construed as a warranty of
the subsurface conditions. Experience has shown that soil and groundwater conditions can vary significantly
over small distances. Inconsistent conditions can occur between explorations that may not be detected by a
geotechnical study. If, during future site operations, subsurface conditions are encountered which vary
appreciably from those described herein, GeoPacific should be notified for review of the recommendations of
this report, and revision of such if necessary.
( Sufficient geotechnical monitoring, testing and consultation should be provided during construction to
confirm that the conditions encountered are consistent with those indicated by explorations.
Recommendations for design changes will be provided should conditions revealed during construction differ
from those anticipated, and to verify that the geotechnical aspects of construction comply with the contract
plans and specifications.
Within the limitations of scope, schedule and budget, GeoPacific attempted to execute these services in
accordance with generally accepted professional principles and practices in the fields of geotechnical
engineering and engineering geology at the time the report was prepared. No warranty, express or implied, is
made. The scope of our work did not include environmental assessments or evaluations regarding the
presence or absence of wetlands or hazardous or toxic substances in the soil, surface water, or groundwater at
this site.
09- 1831 - Hunziker Commercial Building GR 9 GEOPACIFIC ENGINEERING, INC.
August 26, 2009
GeoPacific Project No. 09 -1831
0.0
We appreciate this opportunity to be of service.
Sincerely,
GEOPACIFIC ENGINEERING, INC. �ED PROFE
•• , 2 ' _� r,
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aj EXPIRES: 06 -30 -20 t t
Beth K. Rapp, G.I.T. Scott L. Hardman, P.E.
Project Geologist Principal Engineer
Attachments: References
Figure 1 — Vicinity Map
Figure_ 2 — Site and Exploration Plan
Boring logs (B -1 through B -3)
f1
fl
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GeoPacific Project No. 09 -1831
REFERENCES
Atwater, B.F., 1992, Geologic evidence for earthquakes during the past 2,000 years along the Copalis River,
southern coastal Washington: Journal of Geophysical Research, Vol. 97, p. 1901 -1919.
Carver, G.A., 1992, Late Cenozoic tectonics of coastal northern California: American Association of
Petroleum Geologists -SEPM Field Trip Guidebook, May, 1992.
Geomatrix Consultants, 1995, Seismic Design Mapping, State of Oregon: unpublished report.
1� g P P
Goldfinger, C., Kulm, L.D., Yeats, R.S., Appelgate, B, MacKay, M.E., and Cochrane, G.R., 1996, Active
ij strike -slip faulting and folding of the Cascadia Subduction -Zone plate boundary and forearc in central
and northern Oregon: in Assessing earthquake hazards and reducing risk in the Pacific Northwest, v. 1:
U.S. Geological Survey Professional Paper 1560, P. 223 -256.
Madin, I.P., 1990, Earthquake hazard geology maps of the Portland metropolitan area, Oregon: Oregon
Department of Geology and Mineral Industries Open -File Report 0 -90 -2, scale 1:24,000, 22 p.
Peterson, C.D., Darioenzo, M.E., Burns, S.F., and Burris, W.K., 1993, Field trip guide to Cascadia
paleoseismic evidence along the northern California coast: evidence of subduction zone seismicity in the
central Cascadia margin: Oregon Geology, Vol. 55, p. 99 -144.
Unruh, J.R., Wong, I.G., Bott, J.D., Silva, W.J., and Lettis, W.R., 1994, Seismotectonic evaluation: Scoggins
Dam, Tualatin Project, Northwest Oregon: unpublished report by William Lettis and Associates and
Woodward Clyde Federal Services, Oakland, CA, for U. S. Bureau of Reclamation, Denver CO (in
Geomatrix Consultants, 1995).
Werner, K.S., Nabelek, J., Yeats, R.S., Malone, S., 1992, The Mount Angel fault: implications of seismic -
reflection data and the Woodburn, Oregon, earthquake sequence of August, 1990: Oregon Geology, v.
54, p. 112 -117.
Wong, I. Silva, W., Bott, J., Wright, D., Thomas, P., Gregor, N., Li., S., Mabey, M., Sojourner, A., and
Wang, Y., 2000, Earthquake Scenario and Probabilistic Ground Shaking Maps for the Portland, Oregon,
Metropolitan Area; State of Oregon Department of Geology and Mineral Industries; Interpretative Map
Series IMS -16.
Yeats, R.S., Graven, E.P., Werner, K.S., Goldfinger, C., and Popowski, T., 1996, Tectonics of the
Willamette Valley, Oregon: in Assessing earthquake hazards and reducing risk in the Pacific Northwest,
Vol. 1: U.S. Geological Survey Professional Paper 1560, P. 183 -222, 5 plates, scale 1:100,000.
Yelin, T.S., 1992, An earthquake swarm in the north Portland Hills (Oregon): More speculations on the
seismotectonics of the Portland Basin: Geological Society of America, Programs with Abstracts, v. 24,
no. 5, p. 92.
09- 1831 - Hunziker Commercial Building GR 11 GEOPACIFIC ENGINEERING, INC.
Yom. '2:,, 13910 SW Galbreath Drive, Suite 102
Geo cmfine Sherwood, Oregon 97140 VICINITY MAP
En nl erin9 lnc: = - Tel: (503) 625-4455 Fax: (503) 625 -4405
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Date: 08/25/09
Legend Approximate Scale 1 in = 2,000 ft Drawn by: EKR
Base map: U.S. Geological Survey 7.5 minute Topographic Map Series, Beaverton, Oregon Quadrangle, 1961 (Revised 1984)
and Lake Oswego, Oregon Quadrangle, 1961 (Revised 1984)
Project: Hunziker Commercial Building f Project No. 09 -1831
I FIGURE 1
Tigard, Oregon I
13910 SW Galbreath Drive, Suite 102 SITE PLAN AND
G eo P Sherwood, Oregon 97140
- ioginecnn � Tel: (503) 625-4455 Fax: (503) 625 -4405 EXPLORATION LOCATIONS
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Legend Date: 08/25/09
0 40' Drawn by: EKR
B -1 i I
-$- Boring Designation and Approximate Location APPROXIMATE SCALE 1 " =40'
Project: Hunziker Commercial Building
Tigard, Project No. 09 -1831 I FIGURE 2
Tigard, Oregon
•
l l \e_- 13910 SW Galbreath Drive, Suite 102
GeoPCdi@ Sherwood, Oregon 97140 BORING LOG
? EIIyi00Bllriy'Incf" ` + Tel: (503) 625-4455 Fax: (503) 625-4405
Project: Hunziker Commercial Building Project No. 09 -1831 Boring No. B -1
Tigard, Oregon
m a do 0
^
F- w c m : : N
. N (1) (n N• e C m O)
o > a o.0 s Material Description
Z , � , co
2.5 Inches Asphalt •
5.5 Inches Crushed Rock (Existing Pavement Section)
Medium stiff, SILT (ML), gray, micaceous, trace orange and gray mottling,
damp (Undocumented Fill)
•
3 _
0
2
_ Medium stiff to stiff, SILT (ML), trace very fine grained sand, light brown,
L1 — 8 micaceous, trace orange and gray mottling, trace black staining, damp to moist •
(Willamette Formation) .
•
3-
4—
1
•
lk 5— 9
L�
6: •
Boring Terminated at 6.5 Feet.
• 7—
Note: No seepage or groundwater encountered.
• 8—
LEGEND o
d Date Excavated: 8/11/09
,00t° ut • dad E. Logged By: B. Rapp
7,000 c
Surface Elevation:
Beg Sample Bucket Sample Shelby Tube Sample Seepage Water Bearing Zone Water Level at Abandonment
13910 SW Galbreath Drive, Suite 102
GeoPecifie Sherwood, Oregon 97140 BORING LOG
Engineering Inc : "` Tel: (503) 625-4455 Fax: (503) 625 -4405
Project: Hunziker Commercial Building Project No. 09 -1831 Boring No. B -2
Tigard, Oregon
c
F L F c 3 N
a > o a Material Description
z E v 1
o � m
2.5 Inches Asphalt
4 Inches Crushed Rock (Existing Pavement Section)
Stiff, SILT (ML), light brown, micaceous, damp (Willamette Formation)
1—
K;
Boring Terminated at 1 Foot.
2—
_ Note: No seepage or groundwater encountered.
f —
3
4 -
5
6—
1
7 —
•
8
LEGEND
d Date Excavated: 8/11/09
1 s 4d ® Logged By: B. Rapp
1.000 g
— Surface Elevation:
Bag Sample Bucket Sample Shelby Tube Sample Seepage Water Bearing Zone Water Level at Abandonment
�^ B
- 13910 SW Galbreath Drive, Suite 102 p
GeoP ifMM Sherwood, Oregon 97140 BORING LOG
Engioeerine: Inc. °' "= Tel: (503) 625 -4455 Fax: (503) 625 -4405
Project: Hunziker Commercial Building
Tigard, Oregon Project No. 09 -1831 Boring No. B -3
to
a Z• a g
g 43N
i Q Z 0 a o . Material Description
g aft— l4 0 � CO
!1 2.5 Inches Asphalt
J _ 5 Inches Crushed Rock (Existing Pavement Section)
Medium stiff, SILT (ML), gray, damp (Undocumented Fill)
1 Boring Terminated at 0.8 Foot.
2—
Note: No seepage or groundwater encountered.
I —
3
4 —
5 •
6
l _
7.—
i
I —
8
I —
LEGEND
Date Excavated: 8/11/09
t s Gal
,00to ��ket
old Logged By: B. Rapp
:
1.000 g
Surface Elevation:
Bag Sample Bucket Sample Shelby Tube Sample . Seepage Water Bearing Zone Water Level at Abandonment