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CITY OF TIGARD
Updated October 7, 2016 REVIEWED FOR COD OMPLIANCE
Project No. 16-4211
Approved:
OTC.:
Spectrum Development Permit/Is alliCAL .r "°
Mr. Kurt Dalbey Address: do W -
PO Box 1689 ' `--tom
Lake Oswego, Oregon 97035 Sub.
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Email: kdalbey@gmail.com Br Wiwi.. Date:
CC: Shad Haney (hlhaney@westlakeconsultants.com)
Via email with hard copies mailed upon request OFFICE COPY
SUBJECT: GEOTECHNICAL ENGINEERING REPORT
DURHAM SQUARE
SOUTHWEST OF THE INTERSECTION OF SW 74TH AVENUE AND SW
DURHAM ROAD
TIGARD, OREGON
This report presents the results of a geotechnical engineering study conducted by GeoPacific
Engineering, Inc. (GeoPacific) for the above-referenced project. The purpose of our
investigation 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-5625, dated April 26, 2016 and your subsequent authorization
of our proposal and General Conditions for Geotechnical Services.
SITE AND PROJECT DESCRIPTION
The subject site is located to the southwest of the intersection of SW 74th Avenue and SW
Durham Road in the City of Tigard, Washington County, Oregon. Topography on the site is
generally gently sloping at grades of 10 percent or less. However, along the western property
boundary, topography slopes down at grades of approximately 50 percent down to Fanno
Creek. These steeper slopes are up to about 10 feet tall and are evidence of past grading
activity on the site.
In the central and northern portions of the site, vegetation generally consists of grass and small
brush, as the ground surface is covered with gravel fill material. The southern portion of the site
is heavily vegetated, with brush and small to large trees.
Preliminary plans indicate the proposed development will consist of the construction of two to
three new concrete tilt-up structures, parking areas, and associated underground utilities. We
also understand that a retaining wall is proposed in the northern portion of the site, with an
exposed height of up to 7 feet.
14835 SW 72nd Avenue Tel(503)598-8445
Portland, Oregon 97224 Fax(503)941-9281
Updated October 7, 2016
Project No. 16-4211
REGIONAL AND LOCAL 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 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). In the Willamette River Valley, 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 (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.
REGIONAL SEISMIC SETTING
At least three major fault zones capable of generating damaging earthquakes are thought to exist
in the vicinity of the subject site. These include the Portland Hills Fault Zone, the Gales Creek-
Newberg-Mt. Angel Structural 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 Oaffield 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 7.0 miles
northeast of the site. The Oatfield Fault occurs along the western side of the Portland Hills, and is
about 4.8 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 12.8 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 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).
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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 approximately along the Oregon Coast at depths of between 20
and 40 kilometers below the surface.
SUBSURFACE CONDITIONS
Our site-specific exploration for this report was conducted on June 8. A total of five exploratory
borings (designated B-1 through B-5) were excavated. The borings were excavated to depths
of 10.5 to 35 feet. The approximate locations of our excavations are shown on Figure 2.
Exploration locations were located 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.
The boreholes conducted for this study were drilled using a trailer-mounted drill rig and solid
stem auger methods. At each boring location, 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 an automatic hammer 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
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 and patched with cold-patch asphalt pavement.
Explorations were conducted under the full-time observation of GeoPacific personnel. Soil
samples obtained from the borings 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. 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 exploration 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.
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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 boring logs. Also, please note that subsurface
conditions can vary between exploration locations, as discussed in the Uncertainty and
Limitations section below.
Undocumented Fill: Underlying the ground surface in all exploration locates, we encountered
undocumented fill material. We observed a thin layer of gravel base rock at all exploration
locations, which generally consisted of%"-0 crushed aggregate. Underneath the existing base
rock, the consistency of the fill material was highly variable. The fill material generally consisted
of very soft to medium stiff SILT (ML) with SPT N-values of N=2 to N=6. However, the upper
portion of undocumented fill material in boring B-5, located in the existing driveway alignment
consisted of medium dense silt GRAVEL (GM) with an N-value of N=17. We observed some
charred organic material in the fill, and encountered fine roots and pieces of wood in boring B-4.
The depths of undocumented fill material encountered in our explorations are summarized on
Table 1.
Table 1 —Depths of Undocumented Fill and Buried Topsoil
Exploration Depth of
Designation Undocumented
Fill (ft)
B-1 7.5
B-2 1
B-3 2.5
B-4 14
B-5 7.5
Catastrophic Flood Deposits— Underlying the undocumented fill material in all exploration
locations, we encountered Catastrophic Flood Deposits. The upper two to three feet of these
soils generally consisted of sandy SILT (ML) to silty SAND (SM), which graded to sandy
GRAVEL (GP). The upper portion of these soils was generally stiff or medium dense, but
quickly graded to dense and very dense. Practical auger refusal was obtained at depths of 16,
and 10.5 feet in borings B-1 and B-2, respectively. Catastrophic Flood Deposits extended
beyond the maximum depths of our explorations in all borings.
Soil Moisture and Groundwater
On June 8, 2016, groundwater seepage was encountered below depths of 7.5 and 13.5 feet in
borings B-1 and B-3, respectively. No seepage or groundwater was encountered in the other
borings. However, experience has shown that temporary storm related perched groundwater
within surface soils often occur over native deposits such as those beneath the site, particularly
during the wet season. It is anticipated that groundwater conditions will vary depending on the
season, local subsurface conditions, changes in site utilization, and other factors.
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CONCLUSIONS AND RECOMMENDATIONS
Our investigation indicates 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. In our opinion, there are three main geotechnical issues for project
completion. The first main issue is the presence of undocumented fill materials, which may
complicate site preparation and retaining wall construction. Undocumented fill material with
highly variable consistency was encountered in all exploration locations to depths of up to 14
feet, as summarized on Table 1. The second main issue is the presence of groundwater
seepage at relatively shallow depths. On June 8, 2016, groundwater seepage was encountered
at depths of 7.5 and 13.5 feet in borings B-1 and B-3, respectively. The third main issue for
project construction is the potential for seismically induced settlement, currently estimated to
range from 2 to 3 inches. A Cone Penetrometer Test (CPT) would help refine this range.
The proposed retaining wall in the northern portion of the site should consist of a gravity
Ultrablock wall founded on geosynthetically reinforced rock in order to improve slope stability.
The following report sections provide recommendations for site development and construction in
accordance with the current applicable codes and local standards of practice.
Site Preparation
Areas of proposed buildings, streets, and areas to receive fill should be cleared of vegetation
and any organic and inorganic debris. Existing structures should be demolished and any
cavities structurally backfilled. Inorganic debris should be removed from the site. Organic-rich
topsoil should then be stripped from construction areas of the site or where engineered fill is to
be placed. The estimated average necessary depth of removal in undisturbed, vegetated areas
for moderately to highly organic soils is currently unknown, but is typically on the order of 8 to 12
inches. Deeper stripping may be necessary in localized areas, such as forested parts of the
site. The final depth of soil removal will be determined on the basis of a site inspection after the
stripping/excavation has been performed. Stripped topsoil should be stockpiled only in
designated areas and stripping operations should be observed and documented by the
geotechnical engineer or his representative. Organic materials from clearing should either be
removed from the site or placed as landscape fill in areas not planned for structures.
Undocumented fill material may remain in place in the alignment of the proposed retaining wall
in the northern portion of the site, provided that the retaining wall is designed and constructed
as described in the Ultrablock gravity retaining wall section of this report.
In building areas and areas to receive fill, remaining undocumented fills, buried topsoil, and
subsurface structures (tile drains, basements, driveway and landscaping fill, old utility lines,
septic leach fields, etc.) should be removed and the excavations backfilled with engineered fill.
Undocumented fill material was encountered in all exploration locations to depths of up to 14
feet, as summarized on Table 1 and shown on the attached Site Plan (Figure 2).
Undocumented fill material should be removed from the influence zones of proposed structures,
assumed ata line of 1.5H:1 V from footings.
In parking areas, the undocumented fill material may be evaluated by proofrolling. The
undocumented fill materials are likely suitable for reuse as engineered fill provided they are free
of highly organic material and debris. We recommend full-time monitoring by GeoPacific during
the removal period to assist in identifying materials suitable for re-use as engineered fill, and to
verify that these soils are not mixed with organics or debris.
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Once stripping of a particular area is approved, the area must be ripped or tilled to a depth of 12
inches, moisture conditioned, root-picked, and compacted in-place prior to the placement of
engineered fill or crushed aggregate base for pavement. Exposed subgrade soils should be
evaluated by the geotechnical engineer. For large areas, this evaluation is normally performed
by proof-rolling the exposed subgrade with a fully loaded scraper or dump truck. For smaller
areas where access is restricted, the subgrade should be evaluated by probing the soil with a
steel probe. Soft/loose soils identified during subgrade preparation should be compacted to a
firm and unyielding condition, over-excavated and replaced with engineered fill (as described
below), or stabilized with rock prior to placement of engineered fill. The depth of
overexcavation, if required, should be evaluated by the geotechnical engineer at the time of
construction.
Engineered Fill
All grading for the proposed development should be performed as engineered grading in
accordance with the applicable building code at time of construction with the exceptions and
additions noted herein. Proper test frequency and earthwork documentation usually requires
daily observation and testing during stripping, rough grading, and placement of engineered fill.
Imported fill material must be approved by the geotechnical engineer prior to being imported to
the site. Oversize material greater than 6 inches in size should not be used within 3 feet of
foundation footings, and material greater than 12 inches in diameter should not be used in
engineered fill. In general, we anticipate that soils from planned cuts and utility trench
excavations will be suitable for use as engineered fill provided they are adequately moisture
conditioned prior to compacting.
Engineered fill should be compacted in horizontal lifts not exceeding 8 inches using standard
compaction equipment. We recommend that engineered fill be compacted to at least 95% of
the maximum dry density determined by ASTM D698 (Standard Proctor) or equivalent. Field
density testing should conform to ASTM D2922 and D3017, or D1556. All engineered fill should
be observed and tested by the project geotechnical engineer or his representative. Typically,
one density test is performed for at least every 2 vertical feet of fill placed or every 500 yd3,
whichever requires more testing. Because testing is performed on an on-call basis, we
recommend that the earthwork contractor be held contractually responsible for test scheduling
and frequency.
Site earthwork will be impacted by soil moisture. Earthwork in wet weather would likely require
extensive use of cement or lime treatment, or other special measures, at considerable additional
cost compared to earthwork performed under dry-weather conditions.
Excavating Conditions and Utility Trenches
We anticipate that on-site soils can be excavated using conventional heavy equipment such as
scrapers and trackhoes. 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 undocumented fill soils generally classify as Type B
Soil and temporary excavation side slope inclinations as steep as 1H:1V may be assumed for
planning purposes. The existing native soils classify as Type C Soil and temporary excavation
side slope inclinations as steep as 1.5H:1 V may be assumed for planning purposes. These cut
slope inclinations are applicable to excavations above the water table only. Maintenance of
safe working conditions, including temporary excavation stability, is the responsibility of the
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contractor. Actual slope inclinations at the time of construction should be determined based on
safety requirements and actual soil and groundwater conditions.
Saturated soils and groundwater may be encountered in utility trenches, particularly during the
wet season. Groundwater was encountered at relatively shallow depths in our test pit
explorations. We anticipate that dewatering systems consisting of ditches, sumps and pumps
would be adequate for control of perched groundwater, above the water table. 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 trench backfill be compacted to at least 95% of the maximum dry density
obtained by Standard Proctor ASTM D698 or equivalent. Initial backfill lift thickness 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 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.
Adequate density testing should be performed during construction to verify that the
recommended relative compaction is achieved. Typically, one density test is taken for every 4
vertical feet of backfill on each 200-lineal-foot section of trench.
Structural Foundations
At the time of this report, specific structural loadings have not yet been developed. The
proposed concrete tilt-up structures may be supported on shallow foundations bearing on
competent undisturbed, native soils and/or engineered fill, appropriately designed and
constructed as recommended in this report. Based on our understanding of the proposed
building locations and the results of our exploration program, excavation depths of 1 to 7.5 feet
may be required to reach competent native soils. Undocumented fill material was encountered
in all of our exploration, to depths ranging from 1 to 14 feet. The depths of undocumented fill
material encountered in our explorations are summarized on Table 1. Native soils consist of
medium dense to very dense granular soils and should provide adequate support of structural
loads.
For footing subgrade soils prepared as recommended above, we recommend maximum
allowable bearing pressures of 2,000 pounds per square foot (psf) in design of the below-grade
portions of the structure. The recommended maximum allowable bearing pressures may be
increased by 1/3 the above-recommended value, for short term transient conditions such as
wind and seismic loading. All exterior and interior footings should be founded at least 18 inches
below the lowest adjacent finished grade or below top of slab. Minimum footing widths should
be determined by the project engineer/architect in accordance with applicable design codes.
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Assuming construction is accomplished as recommended herein, and for the foundation loads
anticipated, we estimate total static 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 3/ 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 0.42 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 320 pounds per
cubic foot (pcf), assuming footings are cast against native 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.
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 reinforcing steel bars. GeoPacific should observe foundation
excavations prior to placement of reinforcing steel and formwork, to verify that an appropriate
bearing stratum has been reached and that the actual exposed soils are suitable to support the
planned foundation 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 compacted, crushed aggregate. As a result
of this condition, we recommend foundation excavations be observed to verify subgrade
strength.
Ultrablock Gravity Retaining Wall
We understand that a retaining wall is proposed in the northern portion of the site, with a
maximum exposed height of 7 feet. As shown on the attached gravity Ultrablock wall detail
(Figure 3), the proposed retaining wall is located in the middle of a slope, which consists of soft,
undocumented fill soils. Slope stability analyses performed on the existing slope show that the
slope currently has factors of safety of 1.5 for static conditions and 1.0 for seismic conditions.
Without remedial efforts, the addition of a conventional retaining wall system and fill on the
slope would decrease the stability of the slope further below tolerable limits.
The proposed wall should consist of an Ultrablock gravity retaining wall. We assume that the
grade above the wall will be relatively level and that the grades below the wall will be a
maximum 2H:1 V slope. A 250 pound per square foot(psf) surcharge was applied at the top of
the wall to account for traffic loading. We assume that the surcharge will be offset a minimum
horizontal distance of 2 feet from the back of the wall. The configuration of this wall is shown on
Figure 3.
In order to mitigate slope stability concerns within the undocumented fill present on the slope,
the retaining wall foundation should be overexcavated and backfilled with geosynthetically
reinforced rock. The area from 5 feet in front of the wall face to 2 feet behind the back of the
wall should be excavated to a minimum depth of 6 feet below the ground surface or to
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competent native soils, whichever is shallower. GeoPacific should observe and approve the
subgrade at this point.
Prior to backfilling, a six inch lift of 4-inch quarry spalls or other material approved by the
geotechnical engineer should be placed at the bottom of the excavation and mechanically
compacted. The excavation should then be lined with geogrid. The grids should be rolled out
with the strong direction perpendicular to the face of the wall and not along the wall face.
Excess grid length should be rolled out so that the grid can be wrapped completely over the top
of the finished backfill. Geogrid should consist of Stratagrid SG 350, or approved equivalent
with an ultimate tensile strength of at least 5,000 pounds per foot.
With the geogrid in place, the excavation should be backfilled with 4-inch quarry spalls or other
material approved by the geotechnical engineer. Backfill material should be placed in 1 foot lifts
and mechanically compacted to an unyielding state. When backfilling is complete, the excess
geogrid should then be pulled taught over the top of the backfill. The leveling pad for the first
row of blocks will be placed on top of the geosynthetically reinforced rock.
Wall design calculations for a gravity Ultrablock wall with a maximum exposed height of 7 feet
are attached to this report. Soil parameters used in these analyses were based on typical
values for the native soils encountered in our explorations. The wall should be founded on a
crushed rock leveling pad a minimum of 6 inches thick and should be embedded a minimum of
24 inches. Subgrade soils below the reinforced rock should consist of competent
undocumented fil materials, native soils, or engineered fill. GeoPacific should observe
subgrade soils to verify a suitable bearing stratum is present. If any soft or organic soil zones
are encountered, overexcavation and replacement of the unsuitable soils should be performed.
The depth and extent of any overexcavation should be determined in the field based on actual
conditions exposed.
Wall backfill materials should consist of relatively clean granular materials such as recycled
concrete or crushed aggregate base. Where possible, wall backfill should be compacted to at
least 95% of standard Proctor(ASTM D698) maximum density.
The leveling pad should be carefully constructed and the bottom row of blocks should be
carefully placed level. The second row of blocks should not be placed until adequate wall angle
has been verified. Wall batter should be checked frequently during wall construction, as a
reduced batter will result in reduced factors of safety. The batter is designed as vertical.
Adequate drainage behind and beneath the wall is important for wall performance. A
subsurface drain consisting of 4-inch diameter, perforated pipe should be placed at the back of
the wall as shown on the attached details. The drain pipe and surrounding drain rock should be
wrapped in non-woven geotextile (Mirafi 140N, or approved equivalent) to minimize the potential
for clogging and/or ground loss due to piping. Water collected from the drains should outlet to
the natural area below the walls, or may also be connected to the storm drain system if
practical.
It should be noted that gravity walls such as those planned for the project will generally
experience some minor wall movement. As a result, structural loads other than those
accounted for in the design should not be within the 1.5H:1V plane measured from the back of
the bottom of the wall (including embedded portion). Any structural foundation elements located
within the setback distance should deepened to the point that they no longer impact the wall.
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• Based on the attached calculations and slope stability analyses, the proposed wall will have
adequate factors of safety against sliding, overturning, bearing capacity failure, facing failure,
and slope failure in static and seismic conditions provided that our recommendations for wall
construction are followed. GeoPacific should perform construction of the designed walls
including subgrade inspection, overexcavation requirements, embedment, and backfill
compaction.
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 waddles and silt fences. If used, these erosion control
devices should be in place and remain in place throughout site preparation and construction.
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.
Wet Weather Earthwork
Soils underlying the site are likely to be 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.
A 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 minimize subgrade disturbance caused by
equipment traffic;
➢ 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;
➢ 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
16-4211 -Durham Square GR rev_10062016 10 GEOPACIFIC ENGINEERING,INC.
A
Updated October 7, 2016
Project No. 16-4211
exposed to moisture. Soils which become too wet for compaction should be removed and
replaced with clean granular materials;
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
➢ Straw waddles 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.
Concrete Slabs-on-Grade
Preparation of areas beneath concrete slab-on-grade floors should be performed as
recommended in the Site Preparation section. Care should be taken during excavation for
foundations and floor slabs, to avoid disturbing subgrade soils. 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.
For evaluation of the concrete slab-on-grade floors using the beam on elastic foundation
method, a modulus of subgrade reaction of 150 kcf(87 pci) should be assumed for the medium
stiff native silt soils anticipated at subgrade depth. This value assumes the concrete slab
system is designed and constructed as recommended herein, with a minimum thickness of
crushed rock of 8 inches beneath the slab.
Interior slab-on-grade floors should be provided with an adequate moisture break. The capillary
break material should consist of ODOT open graded aggregate per ODOT Standard
Specifications 02630-2. The minimum recommended thickness of capillary break materials on
re-compacted soil subgrade is 8 inches. The total thickness of crushed aggregate will be
dependent on the subgrade conditions at the time of construction, and should be verified
visually by proof-rolling. Under-slab aggregate should be compacted to at least 90% of its
maximum dry density as determined by ASTM D1557 or equivalent.
In areas where moisture will be detrimental to floor coverings or equipment inside the proposed
structure, appropriate vapor barrier and damp-proofing measures should be implemented.
Appropriate design professionals should be consulted regarding vapor barrier and damp
proofing systems, ventilation, building material selection and mold prevention issues, which are
outside GeoPacific's area of expertise.
Footing and Roof Drains
If the proposed structures will have a raised floors, and no concrete slab-on-grade floors are used,
perimeter footing drains would not be required based on soil conditions encountered at the site
and experience with standard local construction practices. Where it is desired to reduce the
potential for moist crawl spaces, footing drains may be installed. If concrete slab-on-grade floors
are used, perimeter footing drains should be installed as recommended below.
Where used, perimeter footing drains should consist of 3 or 4-inch diameter, perforated plastic
pipe embedded in a minimum of 1 ft3 per lineal foot of clean, free-draining drain rock. The drain
16-4211 -Durham Square GR rev_10062016 11 GEOPACIFIC ENGINEERING,INC.
•
Updated October 7,2016
Project No. 16-4211
• pipe and surrounding drain rock should be wrapped in non-woven geotextile (Mirafi 140N, or
approved equivalent)to minimize the potential for clogging and/or ground loss due to piping.
Water collected from the footing drains should be directed to the local storm drain system or other
suitable outlet. A minimum 0.5 percent fall should be maintained throughout the drain and non-
perforated pipe outlet. The footing drains should include clean-outs to allow periodic maintenance
and inspection. In our opinion, footing drains may outlet at the curb, or on the back sides of lots
where sufficient fall is not available to allow drainage to the street.
Construction should include typical measures for controlling subsurface water beneath the
structure, including positive crawlspace drainage to an adequate low-point drain exiting the
foundation, visqueen covering the exposed ground in the crawlspace, and crawlspace ventilation
(foundation vents). The client should be informed and educated that some slow flowing water in
the crawlspaces is considered normal and not necessarily detrimental to the home given these
other design elements incorporated into its construction. Appropriate design professionals should
be consulted regarding crawlspace ventilation, building material selection and mold prevention
issues, which are outside GeoPacific's area of expertise.
Down spouts and roof drains should collect roof water in a system separate from the footing
drains in order to reduce the potential for clogging. Roof drain water should be directed to an
appropriate discharge point well away from structural foundations. Grades should be sloped
downward and away from buildings to reduce the potential for ponded water near structures.
Pavement Design On Site Private Driveways and Parking Areas
We understand that the proposed new on site automobile driveways and parking areas will be
surfaced with asphalt concrete pavement. We assume the proposed new automobile driveways
will be subjected to an initial two-way ADT (average daily traffic count) of 400 vehicles per day,
and that the automobile parking areas will be subjected to an initial ADT of 100 vehicles per
day. Further, we assumed 3 percent of the vehicles will be heavy trucks (FHWA Class 5 or
greater). For design purposes, we assume that the native soils on the site exhibit a resilient
modulus of at least 4,500 pci, based on the results of our explorations.
Table 2 presents the recommended section thicknesses for the proposed on site automobile
driveways and parking areas that are to be completed as part of the project, under dry weather
construction conditions. In our opinion, this pavement section is suitable to support the
anticipated light levels of traffic.
The pavement sections recommended in Table 2 are for typical volumes of light automobile
traffic. Heavy truck traffic will reduce the design life of the pavements and may lead to
inadequate pavement performance. If heavy truck traffic is anticipated, GeoPacific should be
contacted for additional pavement design recommendations based on the traffic volumes
expected.
16-4211 -Durham Square GR rev_10062016 12 GEOPACIFIC ENGINEERING,INC.
•
Updated October 7, 2016
Project No. 16-4211
Table 2 - Recommended Minimum Dry-Weather Pavement Section
Layer Thickness (inches)
Material Layer Compaction Standard
Driving Lanes Parking Areas
Asphaltic Concrete (AC) 4 3 91% of Rice Density
AASHTO T-209
Crushed Aggregate Base2 2 95% of Modified Proctor
%"-0 (leveling course) ASTM D1557
Crushed Aggregate Base 95% of Modified Proctor
1W-0 12 8 ASTM D1557
Recommended Subgrade 12 12 95% of Standard Proctor
or Approved Subgrade
Any pockets of organic debris or loose fill encountered during subgrade preparation should be
removed and replaced with engineered fill (see Site Preparation Section). 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, the subgrade and construction plan should be reviewed by the project geotechnical
engineer at the time of construction so that condition specific recommendations can be
provided. The moisture sensitive subgrade soils make the site a difficult wet weather
construction project. General recommendations for wet weather pavement construction are
presented below.
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
asphalt compaction test is performed for every 100 to 200 linear feet of paving.
Wet Weather Construction Pavement Section
This section presents our recommendations for wet weather pavement sections, which are for
construction of on-site driving lanes and parking areas. These wet weather pavement section
recommendations are intended for use in situations where it is not feasible to compact the
subgrade soils to Clackamas County requirements, due to wet subgrade soil conditions, and/or
construction during wet weather.
Based on our site review, we recommend a wet weather section with a minimum subgrade
deepening of 6 inches to accommodate a working subbase of additional 1%"-0 crushed rock.
Geotextile fabric, Mirafi 500x or equivalent, should be placed on subgrade soils prior to
placement of base rock.
In some instances it may be preferable to use Special Treated Base (STB) in combination with
overexcavation and increasing the thickness of the rock section. GeoPacific should be
consulted for additional recommendations regarding use of STB in wet weather pavement
sections if it is desired to pursue this alternative. Cement treatment of the subgrade may also
be considered instead of overexcavation. For planning purposes, we anticipate that treatment
of the on-site soils would involve mixing cement powder to approximately 6 percent cement
content and a mixing depth on the order of 12 inches.
16-4211 -Durham Square GR rev_10062016 13 GEOPACIFIC ENGINEERING,INC.
Updated October 7, 2016
Project No. 16-4211
With implementation of the above recommendations, it is our opinion that the resulting
pavement sections will provide equivalent or greater structural strength than the dry weather
pavement section currently planned. However, it should be noted that construction in wet
weather is challenging, and the performance of pavement subgrade depend on a number of
factors including the weather conditions, the contractor's methods, and the amount of traffic the
areas are subjected to. There is a potential that soft spots may develop even with
implementation of the wet weather provisions recommended in this letter. If soft spots in the
subgrade are identified during roadway excavation, or develop prior to paving, the soft spots
should be over-excavated and backfilled with additional crushed rock.
During subgrade excavation, care should be taken to avoid disturbing the subgrade soils.
Removals should be performed using an excavator with a smooth-bladed bucket. Truck traffic
should be limited until an adequate working surface has been established. We suggest that the
crushed rock be spread using bulldozer equipment rather than dump trucks, to reduce the
amount of traffic and potential disturbance of subgrade soils.
Care should be taken to avoid over-compaction of the base course materials, which could
create pumping, unstable subgrade soil conditions. Heavy and/or vibratory compaction efforts
should be applied with caution. Following placement and compaction of the crushed rock to
project specifications (95% of AASHTO T-180), a finish proof-roll should be performed before
paving.
The above recommendations are subject to field verification. GeoPacific should be on-site
during construction to verify subgrade strength and to take density tests on the engineered fill,
base rock and asphaltic pavement materials.
Seismic Design
Structures should be designed to resist earthquake loading in accordance with the methodology
described in the 2012 International Building Code (IBC), ASCE 7, and with applicable Oregon
Structural Specialty Code (OSSC) revisions (current 2014). We recommend Site Class D be
used for design per the OSSC, Table 1613.5.2 and as defined in ASCE 7, Chapter 20, Table
20.3-1. Design values determined for the site using the USGS (United States Geological
Survey) Seismic Design Maps Summary Report, are summarized in Table 3.
Table 3 - Recommended Earthquake Ground Motion Parameters (2016 USGS)
Parameter Value
Location (Lat, Long), decimal 45.403, -122.755
Probabilistic Ground Motion Values,
2% Probability of Exceedance in 50 yrs
Peak Ground Acceleration 0.419 g
Short Period, SS 0.963 g
1.0 Sec Period, S1 0.419 g
Soil Factors for Site Class D:
Fa 1.115
Fv 1.581
Residential Site Value =2/3 x Fa x Ss 0.716 g
Residential Seismic Design Category D
16-4211 -Durham Square GR rev_10062016 14 GEOPACIFIC ENGINEERING,INC.
Updated October 7, 2016
Project No. 16-4211
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. Following site development, soils on the site
will consist of soft to medium stiff silt fill material, medium stiff to stiff silt, loose to medium dense
native sand, and medium dense to very dense gravel. A layer of loose silty sand was
encountered below a depth of 6 feet and a layer of loose sand interbedded with sandy silt was
encountered from 10 to 15 feet in boring B-3. The portions of these layers below the water table
are considered potentially liquefiable.
According to the Oregon HazVu: Statewide Geohazards Viewer, the subject site is regionally
characterized as having a high risk of liquefaction (DOGAMI:HazVu, 2016). A preliminary
assessment of liquefaction induced settlement was performed based on the Standard
Penetration Test N-values obtained from borings on the site. However, these N-values are
considered imprecise due to the solid stem auger/open hole method of drilling and sampling. It
is likely that a significant amount of soil heave and disturbance occurred during sampling,
particularly below groundwater levels, where the soil density is of most interest in a soil
liquefaction evaluation. Soil heave and disturbance during drilling can cause the N-values to be
lower than they would be in an undisturbed condition.
GeoPacific analyzed soil liquefaction potential using the maximum considered peak ground
acceleration, in accordance with Section 1803.5.12 of the 2014 OSSC. The boring log data was
analyzed using the SPT-based methodology and the commercial computer code Liquify5. For
the purposes of liquefaction analyses, we assumed groundwater at depths of 6 and 8.5 feet
below the ground surface. On June 8, 2016 groundwater was encountered at a depth of 8.5
feet. The preliminary assessment of liquefaction hazard indicates that potentially liquefiable
zones exist in the depth interval between about 6 and 15 feet.
More precise estimates of the soil liquefaction hazard can be made by performing a Cone
Penetrometer Tests (CPT) on the site. The CPT method is anticipated to provide a more
reliable estimate of the soil liquefaction hazard on the site because it provides continuous
information regarding stratification of the soils and direct measurements of undisturbed in-situ
soil properties. If desired, GeoPacific can be consulted to coordinate CPT testing on the site,
analyze the CPT results, and present a refined assessment of soil liquefaction potential.
Seismically Induced Settlements
Settlement of the ground surface may occur as a result of earthquake shaking, particularly
where soil liquefaction occurs. It has long been recognized that sands tend to settle and densify
when subjected to earthquake shaking. Using the methodologies of Ishihara/Yoshime and
Idris/Seed, we estimated seismic-induced settlements at the site. For the purpose of this
evaluation, we used estimated ground motions for the design earthquake. We estimated
seismic-induced settlements for both liquefied and non-liquefied soil layers, as well as saturated
and unsaturated soil zones. Results of these estimates are considered imprecise due to the
solid stem auger/open hole method of drilling and sampling, as previously discussed. Based
on the results of our analyses, 2 to 3 inches of seismically induced settlement are estimated on
the site.
Based on this preliminary evaluation, it is our opinion that the proposed structure may
experience settlements on the order of 2 to 3 inches during the assumed seismic event. We
anticipate that differential settlement would be approximately one-half of the total estimated
settlement, measured between two adjacent building foundation components. The project
16-4211 -Durham Square GR rev_10062016 15 GEOPACIFIC ENGINEERING,INC.
Updated October 7, 2016
Project No. 16-4211
• structural engineer and/or architect should evaluate the existing structure to determine if it can
accommodate the estimated seismic settlements without risk of structural collapse. It should be
noted that under the assumed seismic events, some damage may occur to the structure due to
differential settlement. Substantial repair costs and/or loss of use may result from a significant
earthquake event near the site.
In order to lower the risk of damage to the structure in the event of a seismic event, the
proposed structure could be founded on a mat slab, spread footings supported by deep
foundations, or a mat slab supported by deep foundations. If these alternative foundation
systems are desired, GeoPacific can be consulted to provide additional recommendations for
structural foundations. Rammed aggregate piers, or geopiers, may also be a feasible solution
for the site. Geopiers are typically designed and installed by a design-build contractor, but
GeoPacific may be consulted to provide the design-build contractor with information and review
the proposed foundation plan, if that option is selected.
Detailed assessment of lateral spreading hazards are beyond the scope of this study. However,
Based on the depths of the liquefiable layers, the gentle slope of the native soil, and on
horizontal distances from slope faces, the risk of lateral spreading is anticipated to be low.
As previously discussed, the estimates of seismic induced settlements can be refined by using
CPT data instead of SPT N-values. The CPT method is anticipated to provide a more reliable
estimate of the seismically induced settlements on the site because it provides continuous
information regarding stratification of the soils and direct measurements of undisturbed in-situ
soil properties. If desired, GeoPacific can be consulted to coordinate CPT testing on the site,
analyze the CPT results, and present a refined assessment of soil liquefaction potential.
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, 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, expressed 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.
16-4211 -Durham Square GR rev_10062016 16 GEOPACIFIC ENGINEERING,INC.
Updated October 7, 2016
Project No. 16-4211
We appreciate this opportunity to be of service.
Sincerely,
GEOPACIFIC ENGINEERING, INC.
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Benjamin G. Anderson, P.E.
Project Engineer
Attachments: References
Figure 1 —Vicinity Map
Figure 2 —Site Plan and Exploration Locations
Figure 3—Gravity Ultrablock Wall Typical Construction Detail
Boring Logs (B-1 - B-5)
Slope Stability Calculations (2 pages)
Ultrablock Wall Design Calculations (11 pages)
16-4211 -Durham Square GR rev_10062016 17 GEOPACIFIC ENGINEERING,INC.
Updated October 7, 2016
Project No. 16-4211
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, v. 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 prepared for
Oregon Department of Transportation, Personal Services Contract 11688, January 1995.
Goldfinger, C., Kulm, L.D., Yeats, R.S.,Appelgate, B, MacKay, M.E., and Cochrane, G.R., 1996, Active
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.
Oregon Department of Geology and Mineral Industries, HazVu website
(http://www.oregongeology.org/hazvu)
Peterson, C.D., Darioenzo, M.E., Burns, S.F., and Burris, W.K., 1993, Field trip guide to Cascadia
paieoseismic evidence along the northern California coast: evidence of subduction zone
seismicity in the central Cascadia margin: Oregon Geology, v. 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 Gedmatrix 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, v. 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.
16-4211 -Durham Square GR rev_10062016 18 GEOPACIFIC ENGINEERING,INC.
.: f 14835 SW 72nd Avenue
Glinp, I , Portland,Oregon 97224 VICINITY MAP
fraeinetin � Tel: (503)598-8445 Fax: (503)941-9281
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BASE MAP OBTAINED FROM DOGAMI SLIDO STREET VIW, 2016
Date: 09/13/16
• Legend Approximate Scale 1 in=800 ft Drawn by: BGA
Project: Durham Square Project No. 16-4211 FIGURE 1
Tigard, Oregon
a
a 14835 SW 72nd avenue SITE PLAN AND
<' Portland, Oregon 97224
Engineering Inc Tel: (503)598-8445 Fax: (503)941-9281 EXPLORATION LOCATIONS
,
* /
w l A
, *°' �Sh/ nix
Approximate Location of �� ` •, .�.
Proposed Ultrablock e,,,,,,,./
,, ;;, , (` e ,'A'o
Retaining Wall with an Exposed f3 H ,
Height of up to 7 Feet .°r t° ' i .a;, ,,
1 w �. 7.5' B-3
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7.5' '
- / 4, Approximate Site
,�; - -' £,� eie. --,3. Boundary
�a x
r} Y -
i B-2
`'�' North
,
Legend Date: 07/12/16
1 Boring Designation, Approximate Location, and
0 140' Drawn by: BGA
Ilullir Depth of Undocumented Fill APPROXIMATE SCALE 1"=140'
Project: Durham Square Project No. 16-4211 FIGURE 2
Tigard, Oregon
14835 SW 72nd Avenue GRAVITY ULTRABLOCK WALL
so Portland, Oregon 97224
n , Tel: (503)598-8445 TYPICAL CONSTRUCTION DETAIL
7 FT MAXIMUM EXPOSED HEIGHT
Pavement Section or Min.
12-Inch Low Permeability Soil
Relatively Level Conditions
with 250 psf Traffic Surcharge
t
r4 •��-, +
•
• Granulair Backfill Compacted ,r
7 ft Maximum ▪ to 95%of Standard Proctor ;
Exposed Wall Height Maximum Density t
,.�:, •r Existing Slope
t;y
=:', Limit of Excavation
"" 'r :',•'' (Contractor Responsible
for Stable Backcut)
Minimum Embedment=
2 Feet ter'.'?;` ''j` Undocumented Fill
2H:1V Maximum Slope •1* ,14+pt 4r t �} Material
. :4;77"n i tid d • „i 4"Perforated PVC Drain Wrapped in Mirafi 140N
Minimum Depth from
Ground Surface=6 I, "`° "` t y`"'" R i for g' ►' Fabric or Approved Equivalent
Geosyrt tt cal Reinforced
Feet(Unless Native ` Rock 6"Leveling Pad
Solis are Encountered), fl 1 w a.r v k.' tixd
Undocumented Fill .�,te>�. t .a, ; '„,. .2� . , 91..-21
Material41(
Minimum 2 Fee Behind Stratgrid SG350 Geogrid
Minimum 5 Feet Beyond Back of Wall or Approved Equivalent
Wall Face
Native Sand and
Gravel
Notes:
1. GeoPacific should review subgrade soils. Base of wall should be supported on competent undocumented fill materials,
native soils or engineered fill.
2. Use Ultrablock or similar product, 2.5 x 2.5 x 5-foot blocks.
3. Leveling pad and any additional drainage materials should consist of 3/4"-0 crushed aggregate.
4. Backfill behind the wall should consist of 3/4"-0 crushed aggregate or other granular materials pre-approved by
GeoPacific.
5. Walls with a height of 2 blocks or less do not require double-stacked blocks at the base course.
Project: Durham Square Project No. 16-4211 FIGURE 3
Tigard, OR
•
14835 SW 72nd Avenue
Co Portland,Oregon 97224 BORING LOG
[naineering.)nc Tel: (503)598-8445 Fax:(503)941-9281
Project: Durham Square Project No. 16-4211 Boring No. B-1
Tigard, Oregon
a)
r c c a o
N
fitCMaterial Description
Z u, 11 En
o
v) 0 m
[1 3 Soft, SILT(ML), brown, with some charred organic material, moist
(Undocumented Fill)
5 n
6 Grades to sandy
Grades to medium stiff, with gravel-size pieces of cemented sand below 6.5 feet
and very moist to wet
9 V Stiff, sandy SILT(ML)to silty SAND (SM), brown, wet
(Catastrophic Flood Deposits)
25 /Medium dense, silty GRAVEL(GM), gray and reddish brown, wet
}; (Catastrophic Flood Deposits) ®_--_-
0-Medium dense, SAND (SP), fine-to course-grained, wet
(Catastrophic Flood Deposits)
15 M 24
Boring terminated at 16 feet due to practical auger refusal
Groundwater encountered at 7.5
Hole caved to 9.8 feet
20 -
25
30__
35---
LEGEND
Date Drilled: 06/08/16
onto
,o.2,9Logged By: BGA
000
Static Water Table Surface Elevation:
Bag Sample Split-Spoon Shelby Tube Sample at Drilling Static Water Table Water Bearing Zone
14835 SW 72nd Avenue
Gee ¢" Portland,Oregon 97224 BORING LOG
Inglneermg.Inc Tel: (503)598-8445 Fax: (503)941-9281
Project: Durham Square Project No. 16-4211 BoringNo. B-2
Tigard, Oregon
v T C C D o 0
2 N
a j U0 19 c
z �,N .5� 0 �.� Material Description
cn v m
..Medium dense, silty GRAVEL (GM), gray, damp(Undocumented Fill)
- 5 Medium stiff, sandy SILT(ML), brown, moist(Catastrophic Flood Deposits)
5
6 Grades to with increased sand content
7/23
27 Medium dense, sandy GRAVEL (GM), fine-to coarse-grained, moist
10— (Catastrophic Flood Deposits)
Boring terminated at 10.5 feet due to practical auger refusal
No seepage or groundwater encountered
15-
20-
25-
30-
35—
LEGEND Date Drilled: 06/08/16
o "701 Logged By: BGA
Static Water Table Surface Elevation:
Bag Sample Split-Spoon Shelby Tube Sample at Drilling Static Water Table Water Bearing Zone
14835 SW 72nd Avenue
Geo " A` ' Portland, Oregon 97224 BORING LOG
Entdneennu inc Tel: (503)598-8445 Fax: (503)941-9281
Project: Durham Square Project No. 16-4211 Boring No. B-3
Tigard, Oregon
0
0
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-c., gN O'8 Ca) A0)
n =y 2 o
Material Description
a m z 20 c
co v to
,
Soft to medium stiff, SILT(ML), brown, with occasional gravel, moist
_.. (Undocumented Fill)
_ N
8 Medium stiff, SILT(ML), brown, moist(Catastrophic Flood Deposits)
LI 9 Loose, silty SAND (SM), gray and brown, fine-to coarse-grained, with
occasional rounded gravel, moist(Catastrophic Flood Deposits)
- 0 10 Grades to medium dense and without gravel
Grades to wet below 8.5 feet
10— H ...-__
7 Loose, SAND (SP), gray, fine-to medium-grained, wet, with 6" layer of sandy
silt at 10.5 feet, wet(Catastrophic Flood Deposits)
,:;:
15— -
15e„,/, et
10— H
7 L , sandy GRAVEL (GP), gray, subangular to
subrounded, wet(Catastrophic Flood Deposits)
__ / Verydensegravel 17 to 20 feet based on drillingconditions
�✓ t
20—
17
0/
010
25—
I Very dense gravel 26 to 28 feet based on drilling conditions
30
r''
Boring terminated at 35 feet
' Hole caving below 15 feet, so no samples taken below 20 feet
/:1,./////
Groundwater measured at 13.5 feet
35— ;�`•�
LEGEND
a Date Drilled: 06/08/16
loow v a Logged By: BGA
,000• ra
Static Water Table Surface Elevation:
Bag Sample Split-Spoon Shelby Tube Sample at Drilling Static Water Table Water Bearing Zone
14835 SW 72nd Avenue
Geo u k = Portland,Oregon 97224 BORING LOG
Engineering,Inc Tel: (503)598-8445 Fax: (503)941-9281
Project: Durham Square Project No. 16-4211 Boring No. B-4
Tigard, Oregon
m
cc 0= 0
L " 2 5 o= Material Description
z en 0 m
3 Soft, SILT to sandy SILT(ML), brown, with disturbed texture, very moist
(Undocumented Fill)
5— pi
6 Grades to medium stiff, gray, with trace amounts of charred organic material
and fine roots, and moist
3 Grades to soft, with 1-inch chunk of wood at 8.25 feet
10-
4
• r.
Medium dense, sandy GRAVEL (GP), gray, moist
(Catastrophic Flood Deposits)
15— 12
Medium dense, silty SAND (SM), brown, fine-to medium-grained, moist
(Catastrophic Flood Deposits)
Boring terminated at 15.5 feet
No seepage or groundwater encountered
20-
25-
30-
35—
LEGEND Date Drilled: 06/08/16
Or
100 to111
a 10
Logged By: BGA
000 ..
Static Water Table Surface Elevation:
Bag Sample Split-Spoon Shelby Tube Sample at Drilling Static Water Table Water Bearing Zone
f 14835 SW 72nd Avenue
Portland,Oregon 97224 BORING LOG
r cer#».tn, Tel: (503)598-8445 Fax: (503)941-9281
Project: Durham Square Project No. 16-4211 Boring No. B-5
. Tigard, Oregon
_
Tas e a
C C alO
H = 02 i« y N
�° "2 ` �° Material Description
p g Z m 8 m
to U m
17 Medium dense, silty GRAVEL (GM), brown,with some organic debris
(Undocumented Fill)
2 Very soft, SILT(ML), brown, moist(Undocumented Fill)
_ N
12 -Stiff, sandy SILT(ML), brown, with occasional gravel, moist -
(Catastrophic Flood Deposits)
10- pi ' Medium dense, sandy GRAVEL (GP), gray, moist
11 %�(Catastrophic Flood Deposits) ______________-
- Medium dense, silty SAND (SM), brown, fine-to medium-grained, moist
(Catastrophic Flood Deposits)
_ Boring terminated at 11.5 feet
15- No seepage or groundwater encountered
20-
25-
30-
35-
LEGEND -r Date Drilled: 06/08/16
""`loot° Logged By: BGA
000. 10-20-99 Ir
,—
Static Water Table Surface Elevation:
Bag Sample Split-Spoon Shelby Tube Sample at Drilling Static Water Table Water Bearing Zone
•
16-4211 - Durham Square-Proposed Conditions -Static
Name: Silty SAND and Poorly Graded SAND (SM-SP) Model: Mohr-Coulomb Unit Weight: 125 pcf Cohesion': 0 psf Phi': 38 °
Name: Undocumented Fill Model: Mohr-Coulomb Unit Weight: 120 pcf Cohesion': 50 psf Phi': 25 °
Name: Crushed Aggregate Model: Mohr-Coulomb Unit Weight: 135 pcf Cohesion': 0 psf Phi': 40 °
Name: Rock base Model: Mohr-Coulomb Unit Weight: 130 pcf Cohesion': 0 psf Phi': 40 °
Static Factor of Safety: 1.6
150 —
1.6
140 —
W.V.eyi'".e.WiV%' +k�*:'S.
Cru
130 -- ti U
C
0
> 120
110
100
90
0 10 20 30 40 50 60 70 80 90
Distance
16-4211 - Durham Square-Proposed Conditions -Seismic
Name: Silty SAND and Poorly Graded SAND(SM-SP) Model: Mohr-Coulomb Unit Weight: 125 pcf Cohesion': 0 psf Phi': 38 °
Name: Undocumented Fill Model: Mohr-Coulomb Unit Weight: 120 pcf Cohesion': 50 psf Phi': 25°
Name: Crushed Aggregate Model: Mohr-Coulomb Unit Weight: 135 pcf Cohesion': 0 psf Phi': 40 °
Name: Rock base Model: Mohr-Coulomb Unit Weight: 130 pcf Cohesion': 0 psf Phi': 40 °
Pseudostatic Factor of Safety: 1.1
150 —
1.1
140
Cru
130
0
co 120
_N
W
110
100
90
0 10 20 30 40 50 60 70 80 90
Distance
u - BLocK,t: c.
UltraWall
Version: 4.0.16130
Project: 16-4211 -Durham Square
Location: Site Location
Designer: DPT
Date: 10/3/2016
Section: Section 1
Design Method: NCMA 09 3rd_Ed
Design Unit: Ultrablock
Seismic Acc: 0.220
SOIL PARAMETERS coh y t
Retained Soil: 26 deg 0 psf 120 pcf
Foundation Soil: 36 deg 0 psf 130 pcf
Leveling Pad: 36 deg 0 psf 130 pcf
Crushed Stone
GEOMETRY
• Design Height: 9.00 ft Live Load: 250 psf
Wall Batter/Tilt: 0.00/0.00 deg Live Load Offset: 0.00 ft
Embedment: 2.00 ft Live Load Width: 0 ft
Leveling Pad Depth: 4.00 ft Dead Load: 0 psf
Slope Angle: 5.0 deg Dead Load Offset: 0.0 ft
Slope Length: 100.0 ft Dead Load Width: 0 ft
Slope Toe Offset: 0.0 ft Leveling Pad Width: 6.42 ft
Vertical 6 on Single Depth Toe Slope Angle: 22.00
Toe Slope Length: 100.00
Toe Slope Bench: 0.00
FACTORS OF SAFETY(Static/Seismic)
Sliding: 1.50/1.125 Overturning: 1.50/1.125
Bearing: 2.00/1.5
RESULTS(Static/Seismic)
FoS Sliding: 1.65 (Ivlpd)/1.61 FoS Overturning: 1.70/1.67
Bearing: 1518.65/1458.34 FoS Bearing: 34.86/36.30
Name Elev ka kae Pa Pae Pir -PaC • FSsI FoS OT siesFSsl FoSSeisOT
1X 7.38-a372 0.454 59 ,` 72 79 0 88.78 704 100.00 8.75
1X 4.92 0.372 0.454 372 454 159 0 24.80 1.70 30.04 2.01
2X 2X 2.46 0.586 0.695 1504 1784 317 0 9.45 2 77 10.58 263
2X 2X 0.00 0.517 0 617 2514 3000 476 0 1.6515.313 1.86 1.61(5.363 1.67
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification, and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 1
•
U TR.BLOCK, r C.
NOTES ON DESIGN UNITS
The wall section is designed on a'per unit width bases'(Ib/ft/ft of wall or kN/m/meter of wall). In the calculations the
software shows lb/ft or kN/m, neglecting the unit width factor for simplicity.
The weights for the wall unit are shown as lbs/ft3 (kN/m3). For SRW design a 1 sf unit is typically 1 ft deep, 1.5 ft
wide and 8 inches tall (or 1 ft3).therefore a typical value of 120 pcf is shown. With larger units the unit weight will
vary with the size of the unit. Say we have 4 ft wide unit, 1.5 ft tall and 24 inches deep with a tapered shape(sides
narrow), built with 150 pcf concrete. We add up the concrete,the gravel fill and divide by the volume and the results
may come out to 140 pcf, as shown in the table. The units with more gravel may have lower effective unit weights
based on the calculations.
Hollow Units
Hollow units with gravel fill are treated differently in AASHTO. If the fill can fall out as the unit is lifted, then AASHTO
only allows 80% of the weight of the fill to be used for eccentricity(overturning calculations). In the properties page
for the units the weight of the concrete may be as low as 75 pcf. This is the effective unit weight of the concrete only
(e.g. the weight of the concrete divided by the volume of the unit). The density of the concrete maybe 150 pcf, but not
the effective weight including the volume of the void spaces used for gravel fill.
Rounding Errors
When doing hand calculations the values may vary from the values shown in the software. The program is designed
using double precision values(64 bit precision: 14 decimal places). Over several calculations the results may differ
from the single calculation the user is making, probably inputting one or two already rounded values.
Result Rounding
As noted above the software is based on double precision values. For example, using an NCMA design method an
allowable factor of safety of 1.5 the software may calculate a value of 1.49999999999999, since this is less than 1.5,
it would be false (NG),even though the results shown is 1.50(results are rounded to 2 places on the screen). In the
design check we round to 2 decimal places to check against the suggested value(1.49999999999 rounds to 1.50).
Given the precision of the calculation,this will provide a safe design even though the'absolute'value is less than the
minimum suggested.
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review, verification, and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 2
u TR"BLOCK,INC.
DESIGN DATA
TARGET DESIGN VALUES (Factors of Safety-Static/Seismic)
Minimum Factor of Safety for the sliding along the base FSsI =1.50/1.125
Minimum Factor of Safety for overturning about the toe FSot=1.50/1.125
Minimum Factor of Safety for bearing(foundation shear failure) FSbr=2.00/1.500
MINIMUM DESIGN REQUIREMENTS
Minimum embedment depth Min emb=2.00 ft
INPUT DATA
Geometry
Wall Geometry
Design Height,top of leveling pad to finished grade at top of wall H=9.00 ft
Embedment, measured from top of leveling pad to finished grade emb=2.00 ft
Leveling Pad Depth LP Thickeness=4.00 ft
Face Batter, measured from vertical i=0.00 deg
Slope Geometry
Slope Angle, measured from horizontal R=5.00 deg
Slope toe offset, measured from back of the face unit STL_offset=0.00 ft
Slope Length, measured from back of wall facing SL_Length=100.00 ft
NOTE: If the slope toe is offset or the slope breaks within three times the
wall height, a Coulomb Trial Wedge method of analysis is used.
Surcharge Loading
Live Load, assumed transient loading(e.g. traffic) LL=250.00 psf
Live Load Offset, measured from back face of wall LL offset=0.00 ft
Live Load Width, assumed strip loading LL width=0.00 ft
Dead Load, assumed permanent loading(e.g. buildings) DL=0.00 psf
Dead Load Offset, measured from back face of wall DL offset=0.00 ft
Dead Load Width, assumed strip loading DL width=0.00 ft
Soil Parameters
Retained Zone
Angle of Internal Friction N=26.00 deg
Cohesion coh=0.00 psf
Moist Unit Weight gamma=120.00 pcf
Foundation
Angle of Internal Friction cp=36.00 deg
Cohesion coh=0.00 psf
Moist Unit Weight gamma=130.00 pcf
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification, and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 3
U_TR BL OCK,t C.
RETAINING WALL UNITS
STRUCTURAL PROPERTIES:
N is the normal force[or factored normal load]on the base unit
The default leveling pad to base unit shear is 0.8 tan(cp)or
may be the manufacturer supplied data. cp is assumed to be 40 degrees for a stone leveling pad.
Table of Values:
Unit Ht(in) — Width(in) Depth(in) Equiv_Density(pcf) Equiv_CG(in)
Cap 14.75 59.00 29.50 140.00 14.75
Full 29.50 59.00 2950140.00 14.75
Doubled 29.50 59.00 59.00 140.0029.50
Triple 29.50 59.00 88.50 140.00
44.25
15 in Tall Unit 14.75 ._. 59.00 .29.50 140.00
14.75
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification, and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 4
•
U TR.BLOCK,I C.
FORCE DETAILS
The details below shown how the forces and moments are calculated for each force component. The values shown
are not factored. All loads are based on a unit width(ppf/kNpm).
Layer Block Wt I X-Arm Moment Sod Wt X-Arm Moment
1 846.08 123 1039.97.... 4328 ....... . 2.61 ......._, 112.79
2 846.081.23 1039.97 229.99 2.87 660.57
3 1692.15 2.46 . .. 4159.88 0.00 4.92 0.00
4_.. 1692.15 2.46 4159.$$
Block Weight(Force v)=block: 5076 X-Arm=2.05 ft
Soils Block Weight(Force v) =273 ppf X-Arm=2.83 ft
Active Earth Pressure Pa=2514 ppf
Pa_h(Force H)= Pa cos(batter+S)=2514 x cos( 15.3+ 19.5)=2065 ppf
Y-Arm=3.00 ft
Pa_v(Force V)=Pa sin(batter+b)=2514 x sin( 15.3+ 19.5)= 1434 ppf
X-Arm=4.10ft
Live Load Pq= 1164 ppf
Pq_h(Force H)=Pq cos(batter+6)= 1164 x cos(15.3+ 19.5)=956 ppf
Y-Arm=4.50ft
Pq_v(Force V)= Pq sin(batter+b)= 1164 x sin(15.3+ 19.5)=664 ppf
X-Arm=3.69ft
Passive Earth Pressures
Passive earth pressures are used for resistance of the Leveling Pad, but may be extended upward to assist
with the resistance of the wall facing for walls that have deep embedments.
Passive Earth Pressure:
kp=3.85
Pp=8011.83 ppf
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification, and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 5
U TR;BLOCK,I C.
CALCULATION RESULTS
OVERVIEW
UltraWall calculates stability assuming the wall is a rigid body. Forces and moments are calculated about
the base and the front toe of the wall.The base block width is used in the calculations.The concrete units and
granular fill over the blocks are used as resisting forces.
EARTH PRESSURES
The method of analysis uses the Coulomb Earth Pressure equation (below)to calculate active earth
pressures.Wall friction is assumed to act at the back of the wall face.The component of earth pressure is assumed to
act perpendicular to the boundary surface.The effective b angle is b minus the wall batter at the back face. If the
slope breaks within the failure zone, a trial wedge method of analysis is used.
EXTERNAL EARTH PRESSURES
Effective b angle(3/4 retained phi) b=19.5 deg
Coefficient of active earth pressure ka=0.517
External failure plane p=56 deg
Effective Angle from horizontal Eff.Angle=74.72 deg
Coefficient of passive earth pressure: kp= (1 +sin(cp))/(1 -sin(cp)) kp=3.85
coo +i)a
Ka:–
2 / 5,.,$i+,,._ a.;@i—is
a
co3(1) •cos(i—31 1+
ll III 405(81—i)COS i+
WO: stone within units
W1: facing units
W2: stone over the tails
W9: Driving force Pa
WI0: Driving Surcharge load Paq
W11: Driving Dead Load Surchage Paqd
FORCES AND MOMENTS
The program resolves all the geometry into simple geometric shapes
coordinates are referenced to a zero point at the front toe of the base bloc
%9r �
UNFACTORED LOADS ;, Pq
Name 'Factor yiForce(V)iForce(H) X lens Y-len Mo � Mr r y
P
_,Face Blocks(W1) 1 00 5076 2.05; -- -- '10400: H v
Soil Wedge(W2) 1 00 273 2 83 773
LvlPad(W18) 1.00_ 3597 � ,- , ,�, ,� ,.1;r
Pah 1.00 2066 3.00 6196 �'
Pa_v 1.00 1434 4.10` 5876.. ��
Pq h 100 — 956 450 4303
1 00 664 3 69° - 2448 {
Pkv
Sum V/H 1.00 , 11045 3021 'Sum Mom 10499'19498
Note: live load forces and moments are not included
in SumV or Mr as live loads are not included as resisting forces.
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification,and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 6 1
U TR BLOCK,I C.
BASE SLIDING
Sliding at the base is checked at the block to leveling pad interface between the base block and the leveling
pad. Sliding is also checked between the leveling pad and the foundation soils.
Forces Resisting sliding=W1 +W2+Pay+Pqv
5076+273+1434+664 N=7448 ppf
Resisting force at pad=N tan(slope)+intercept x L
7448 x tan(33.9)+0.0 x 4.9 Rf1 =5000
where L is the base block width
Friction angle is the lesser of the leveling pad and Fnd cp=36.00 deg
N1 includes N(the leveling pad)+leveling pad(LP)
7448+3597 N1 = 11045 ppf
Passive resistance is calculated using kp=(1 +sin(36))/(1 -sin(36)) kp=3.85
Pressure at top of resisting trapezoid,dl =2.00 Fp1 = 1001.48
Pressure at base of resisting trapezoid,d2=2.00 Fp2= 1001.48
Depth of trapezoid depth =0.00
Pp=(Fp1 + Fp2)/2*depth 8011.83
Resisting force at fnd=(N1 tan(phi)+c L)+Pp
11045 x tan(36)+0 x 6.9+8012 Rf2= 16036
where LP=Ivl pad thickness*130pcf*(L+Ivl pad thickness/2)
Driving force is the horizontal component of Pah+ Pqh
2065+956 Df=3021
FSsI= Rf/Df FSsI=1.65/5.31
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification,and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 7
U TR BLOCK, l C.
OVERTURNING ABOUT THE TOE
Overturning at the base is checked by assuming rotation about the front toe by the block mass and the soil
retained on the blocks.Allowable overturning can be defined by eccentricity(e/L). For concrete leveling pads
eccentricity is checked at the base of the pad.
Moments resisting eccentricity=M1 +M2+MLvIPad+MPav+MPqv
10400+773+5876+2448 Mr=19498 ft-lbs
Moments causing eccentricity=MPah+MPq +MPqv
6196+4303 Mo=10499 ft-lbs
e= U2-(Mr-Mo)/N1
e=4.92/2-(19498- 10499)/11045 e=1.25
e/L=0.25
FSot=Mr/Mo
FSot=19498/10499 FSot=1.86
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification, and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 8
U TR'BLOCK, C.
I.
ECCENTRICITY AND BEARING
Eccentricity is the calculation of the distance of the resultant away from the centroid of mass. In wall design
the eccentricity is used to calculate an effective footing width.
Calculation of Eccentricity
SumV= (W1 +W2+LL+Pa_v+Pq_v)
e=U2-(SumMr+M_LL-SumMo)/(SumV+LL)
e=4.92/2-(8999/7447.92) e=1.250 ft
Calculation of Bearing Pressures
Qult=c*Nc+q*Nq +0.5*y*(B')*Ng
where:
Nc=50.59
Nq =37.75
Ng=56.31
c=0.00 psf
q=780.00 psf
B'=B-2e+Ivlpad=6.42 ft
Gamma(LP)=130 pcf
Calculate Ultimate Bearing, Qult Qult=52933 psf
Bearing Pressure=(SumVert/B')+((2B+LP depth)/2*LP depth*gamma) sigma=1518.65 psf
Calculated Factors of Safety for Bearing Quit/sigma=34.86
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification, and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 9
U TR.'BLOCK,! C.
SEISMIC CALCULATIONS
The loads considered under seismic loading are primarily inertial loadings.The wave passes the structure
putting the mass into motion and then the mass will try to continue in the direction of the initial wave. In the
calculations you see the one dynamic earth pressure from the wedge of the soil behind the reinforced mass, and then
all the other forces come from inertia calculations of the face put into motion and then trying to be held in place.
Design Ground Acceleration A=0.220
Horizontal Acceleration[kh=A/2] kh =0.110
Vertical Acceleration kv=0.000
INERTIA FORCES OF THE STRUCTURE
Face(Pif)=(W1)*kh(ext)=5076.46*0.110
Pif=475.95 ppf
SEISMIC THRUST
Kae Kae=0.617
D_Kae= Kae-Ka=(0.617-0.000) D_Kae=0.100
Pae=0.5*gamma*(H)^2*D_Kae Pae=485.63 ppf
Pae_h = Pae*cos(i ) Pae_h=398.88 ppf
Pae_v=Pae*sin(5) Pae_v=277.00 ppf
TABLE OF RESULTS FOR SEISMIC REACTIONS
Name Force(t/)Force(H) X len Y len _--Mo Alt
Face Blocks(W1) 5076.458 2.049 - — 10399.69
Soil Block(W2) 273.262° 2.83 - 773.36
Pa_h —...... 2065.291 - 3.0 6195.87
Pa v 1434.2154 — 4.097 - - 5876.3
PW — 475.952 :.; 5 4 '2570.14' —
Pae h 398.884 -- 5.4 2153.97 --
Pae v 277.0 - 4.097 * -- 1134.93
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification,and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 10
I
•
ti TR SLOCK,1 C.
SEISMIC SLIDING
The target factor of safety for seismic is 75%of the static value. Live loads are ignored in the analyses
based on the basic premise that the probability of the maximum acceleration occuring at the exact same instant as
the maximum live load is small.
Details are only shown for sliding at the base of blocks,a check is made at the foundation level with the
answer only shown.
The vertical resisting forces is W1 +W1 +Pay+Paev SumVs=7061
Resisting force=SumVs*tan(phi)+ intercept x L FRe=4740 ppf
Driving force=Pa_h+Pae_h+Pif
=2065+399+476 FDr=2940 ppf
FOS= FRe/FDr[leveling pad/foundation] FoS=1.61 /5.36
SEISMIC OVERTURNING
Overturning is rotation about the front toe of the wall. Eccentricity is also a check on overturning
Resisting Moment=M1 +M2+ MPav+MPaev SumMrS=18184 ft ppf
Driving Moment=MPav+MPaeh+MPif SumMoS= 10919.99 ft ppf
Factor of Safety=SumMrS/SumMoS FoS= 1.67
SEISMIC BEARING
Bearing is the ability of the foundation to support the mass of the structure.
Qult=c*Nc+q*Nq+ 0.5*gamma*(B')*Ng
where:
Nc=50.59
Nq =37.75
Ng=56.31
c=0.00 psf
q=780.00 psf
Calculate Ultimate Bearing,Qult(seismic) Qult= 52932.87 psf
eccentricity(e) e=1.430
Equivalent Footing Width, B'= L-2e+Ivl pad B'=6 ft
Bearing Pressure=sumVs/B'+2B'+LP depth)/2*LP depth sigma=1458 psf
Factor of Safety for Bearing=Quit/Bearing FoS=36
Note: Calculations and quantities are for PRELIMINARY ANALYTICAL USE ONLY and MUST NOT be used for final
design or construction without the independent review,verification, and approval by a qualified professional
engineer.
UltraWall 4.0.16130 Page 11