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GEOTECHNICAL REPORT
BENSON DRIVE SOUTH AND
SOUTHEAST PETROVITSKY ROAD
Renton, Washington
PROJECT NO. 19-122
May 2019
Prepared for:
TA Renton BP, LLC
________________________________________________
3213 Eastlake Avenue East, Suite B
Seattle, WA 98102
T. (206) 262-0370
F. (206) 262-0374
Geotechnical & Earthquake
Engineering Consultants
May 13, 2019
PanGEO Project No. 19-122
Ms. Michelle Woodward
TA Renton BP, LLC
2600 North Dallas Parkway, Suite 370
Frisco, Texas 75234
Subject: Geotechnical Report
Proposed Retail Development
Benson Drive South and Southeast Petrovitsky Road
Renton, Washington
Dear Ms. Woodward:
As requested, PanGEO, Inc. is pleased to present this geotechnical report to assist the
project team with the design and construction of the proposed retail development located
in the northeast corner of the intersection of Benson Drive South and Southeast Petrovitsky
Road in Renton, Washington.
In preparing this report, we observed and logged the drilling of eight test borings at the site
and conducted our engineering analyses. In summary, our test borings encountered up to
about 4 feet of fill overlying glacially consolidated soils and highly weathered bedrock.
In our opinion, the proposed buildings may be supported on spread footings bearing on
competent native soils or on structural fill placed on competent native soils.
We appreciate the opportunity to be of service. Should you have any questions, please do
not hesitate to call.
Sincerely,
Scott D. Dinkelman, LEG
Senior Engineering Geologist
19-122 Benson Drive and Petrovitsky Road Page 1 PanGEO, Inc.
TABLE OF CONTENTS
Section Page
1.0 GENERAL .................................................................................................................1
2.0 SITE AND PROJECT DESCRIPTION .....................................................................1
3.0 SUBSURFACE EXPLORATIONS ...........................................................................3
3.1 SITE GEOLOGY ................................................................................................3
3.2 SUBSURFACE EXPLORATION ...........................................................................3
3.3 SOIL CONDITIONS............................................................................................4
3.4 GROUNDWATER ..............................................................................................5
4.0 INFILTRATION CONSIDERATIONS ....................................................................6
5.0 GEOTECHNICAL RECOMMENDATIONS ...........................................................6
5.1 SEISMIC DESIGN PARAMETERS ........................................................................6
5.2 BUILDING FOUNDATIONS ................................................................................7
5.2.1 Lateral Resistance ...........................................................................8
5.2.2 Perimeter Footing Drains ...............................................................8
5.2.3 Footing Subgrade Preparation .......................................................9
5.3 FLOORS SLABS ................................................................................................9
5.4 RETAINING WALL DESIGN PARAMETERS ........................................................10
5.4.1 Lateral Earth Pressures ..................................................................10
5.4.2 Surcharge ........................................................................................10
5.4.3 Lateral Resistance ...........................................................................10
5.4.4 Wall Drainage .................................................................................11
5.4.5 Wall Backfill....................................................................................11
5.5 PERMANENT CUT AND FILL SLOPES ................................................................11
6.0 EARTHWORK CONSIDERATIONS .......................................................................12
6.1 STRIPPING, CLEARING AND SUBGRADE PREPARATION ....................................12
6.2 PERCHED SEEPAGE CONTROL .........................................................................12
6.3 TEMPORARY EXCAVATIONS AND SHORING .....................................................13
6.4 MATERIAL REUSE ...........................................................................................13
6.5 STRUCTURAL FILL AND COMPACTION .............................................................13
6.6 WET WEATHER CONSTRUCTION .....................................................................14
6.7 EROSION CONSIDERATIONS .............................................................................15
7.0 ADDITIONAL SERVICES .......................................................................................16
8.0 CLOSURE .................................................................................................................16
9.0 REFERENCES ...........................................................................................................18
ATTACHMENTS:
Figure 1 Vicinity Map
Figure 2 Site and Exploration Plan
Appendix A Boring Logs
Figures A-1 and A-1a Terms and Symbols for Boring and Test Pit Logs
Figures A-2 to A-9 Logs of Test Borings PG-1 through PG-8
19-122 Benson Drive and Petrovitsky Road Page 1 PanGEO, Inc.
GEOTECHNICAL REPORT
PROPOSED RETAIL DEVELOPMENT
BENSON DRIVE SOUTH AND SOUTHEAST PETROVITSKY ROAD
RENTON, WASHINGTON
1.0 GENERAL
As requested, PanGEO is pleased to present this geotechnical report for the proposed retail
development to be located northeast corner of the Benson Drive South and Southeast
Petrovitsky Road in Renton, Washington. This study was performed in general accordance
with our mutually agreed scope of services outlined in our proposal dated April 12, 2019.
Our scope of services included reviewing readily available geologic and geotechnical data,
drilling eight borings, conducting a site reconnaissance, and preparing this report.
2.0 SITE AND PROJECT DESCRIPTION
The subject is comprised of three separate parcels located at 17426 Benson Drive South,
10810 Southeast Petrovitsky Road and 10828 Southeast Petrovitsky Road in the northeast
corner of the intersection of Benson Drive South and Southeast Petrovitsky Road in
Renton, Washington. The approximate location of the site is shown on Figure 1, Vicinity
Map.
The three parcels have an aggregate area of approximately 1.67 acres. The layout of the
site is shown on Figure 2, Site and Exploration Plan. Plate 1, below shows an aerial view
of the site. The approximately L-shaped property is bordered to the northwest by a two-
story office building, to the north by a single-story church, to the east by two single-story
office buildings, to the west by Benson Drive South, and to the south by Southeast
Petrovitsky Road. The site slopes down from east to west, with about 8 feet of elevation
change across the approximate 300-foot length of the site.
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Plate 1: Aerial view
of the site.
Benson Drive is
along the left side of
photo. Southeast
Petrovitsky Road is
along the bottom.
(Bing Maps)
Plate 2: View from
northwest corner of
the site looking site to
the south-southeast.
The site is currently developed with three one-story buildings that are vacant or being used
as offices. We understand it is planned to demolish the existing structures and redevelop
the site with a bank building, a convenience store with a detached fueling island, and three
retail buildings. The proposed development layout is shown on Figure 2.
The proposed buildings will be one-story in height and will be constructed at or near
existing site grades and we anticipate cuts and fills of less than five feet will be required to
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May 13, 2019
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achieve construction subgrade elevations. The proposed buildings will be surrounded by
asphalt paved parking and drive areas.
The conclusions and recommendations in this report are based on our understanding of the
proposed development, which is in turn based on the project information provided. If the
above project description is incorrect, or the project information changes, we should be
consulted to review the recommendations contained in this study and make modifications,
if needed. In any case PanGEO should be retained to provide a review of the final design
to confirm that our geotechnical recommendations have been correctly interpreted and
adequately implemented in the construction documents.
3.0 SUBSURFACE EXPLORATIONS
3.1 SITE GEOLOGY
General geologic information for the project area was obtained by reviewing the Geologic
Map of the Renton Quadrangle, King County, Washington (Mullineaux, 1965) and the
Geologic Map of the Tacoma 1:100,000-scale Quadrangle, Washington (Schuster et al,
2015). Based on our review, the geologic units in the vicinity of the site consist of Vashon
till – Geologic Map Unit Qgt, with Renton Formation sedimentary units mapped nearby –
Geologic Map Unit Ec2pg.
Vashon till is described as consisting of an unsorted deposit (diamict) of clay, silt, sand and
gravel that has been glacially transported and deposited. This soil has been directly
deposited by a glacier and overridden by several thousand feet of glacial ice and is typically
dense to very dense.
The Renton Formation sedimentary unit is locally classified as part of the Puget Group and
described as an interbedded sedimentary rock consisting of sandstone, siltstone, shale,
claystone, carbonaceous shale and coal beds. This unit is considered the bedrock unit in
this area.
3.2 SUBSURFACE EXPLORATION
We drilled and logged eight borings at the site on April 23, 2019. The borings were drilled
using a track-mounted EC95 drill rig owned and operated by Boretec Drilling, Inc. under
subcontract to PanGEO and were logged by a geologist with our firm. The borings were
drilled to a maximum depth of about 16 feet below existing grade. The approximate boring
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locations were located in the field by measuring from property corners and site features
and are shown on Figure 2, Site and Exploration Plan.
Standard Penetration Tests (SPT) were performed at 2½- to 5-foot depth intervals using a
standard, 2-inch diameter split-spoon sampler. The sampler was advanced with a 140-
pound drop hammer falling a distance of 30 inches for each strike, in general accordance
with ASTM D1586, Standard Test Method for Penetration Test and Split Barrel Sampling
of Soils.
The soils were logged in general accordance with ASTM D2487 Standard Practice for
Classification of Soils for Engineering Purposes and the system summarized on Figure A-
1 and Figure A-1a, Terms and Symbols for Boring and Test Pit Logs.
3.3 SOIL CONDITIONS
For a detailed description of the subsurface conditions encountered at each exploration
location, please refer to our boring logs provided in Appendix A. The stratigraphic contacts
indicated on the boring logs represent the approximate depth to boundaries between soil
units. Actual transitions between soil units may be more gradual or occur at different
elevations. The descriptions of groundwater conditions and depths are likewise
approximate. The following is a generalized description of the soils encountered in the
borings.
Asphalt: Test borings PG-1, PG-2, PG-5, PG-6, PG-7 and PG-8 were located in
asphalt paved parking and drive areas. At these locations we encountered between
two and five inches of asphalt surfacing.
Topsoil: Borings PG-3 and PG-4 were located outside of paved areas. In these areas,
we encountered a surficial layer of topsoil comprised of about six inches of silty sand
with organics and roots.
Fill: Below the asphalt at the locations of PG-1, PG-5, PG-7 and PG-8, we
encountered fill. The fill generally consisted of a few inches of gravel over sandy silt
with varying amounts of gravel and cobbles. This unit ranged from 2½ to 4½ feet
thick. The approximate fill thicknesses are identified on the boring logs and on Figure
2.
Weathered Vashon Till (Qgt): The native soil below the fill and in areas where fill
was not encountered consists of medium dense to very dense silty fine to medium sand
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with gravel and which we classified as Vashon Till. At the base of this unit, from
approximately 10 to 14 feet below grade, the till graded to dense to very dense.
Perched groundwater was encountered throughout this unit.
The Vashon till encountered at our boring locations is consistent with the geologic
mapping of this area. Test borings PG-4 and PG-6 were terminated in this unit.
Renton Formation (Ec2pg): With the exception of borings PG-4 and PG-6, all of our
other test borings encountered a hard sandy silt with gravel below the weathered
Vashon Till. We classified the hard silt as the Renton Formation (bedrock). The
Renton Formation was identifiable with the increase in coal fragments present in the
samples. This unit is highly weathered to a residual soil (relative weathering RVI) at
the top and graded to less weathered with depth.
The Renton Formation encountered at our boring locations is consistent with the upper
unit of the Puget Group mapping of the region. In test boring PG-1 this unit was only
slightly weathered at approximately 13 feet (relative weathering RII) and in test boring
PG-7 this unit was highly weathered at approximately 15 feet (relative weathering
RIV). Test borings PG-2, PG-3, PG-5, and PG-8 terminated in the residual soil
(relative weathering RVI) portion of this unit.
Our subsurface descriptions are based on the conditions encountered at the time of our
exploration. Soil conditions between our exploration locations may vary from those
encountered. The nature and extent of variations between our exploratory locations may
not become evident until construction. If variations do appear, PanGEO should be
requested to reevaluate the recommendations in this report and to modify or verify them in
writing prior to proceeding with earthwork and construction.
3.4 GROUNDWATER
Increased soil moisture and light groundwater seepage was encountered beginning at
approximately 4 feet below grade during drilling. This moisture is likely perched
groundwater that has developed in lenses of highly permeable soil within the weathered till
formation. If seepage is encountered, we anticipate seepage rates will be light to moderate.
Groundwater levels will change depending on the season, amount of rainfall, surface water
runoff, and other factors. Generally, the water level is higher and seepage rates are greater
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in the wetter, winter months (typically October through May). During periods of
significant precipitation, perched groundwater may also be present at the fill-till contacts.
4.0 INFILTRATION CONSIDERATIONS
The native soils underlying the site consist of Vashon till, a medium dense to very dense
deposit comprised of clay, silt, sand, and gravel. Till is generally not a suitable receptor
soil for infiltration due to the high fines content and density. Where loosened by
weathering infiltration rates of about ½ inch per hour may be obtained. Where
unweathered, infiltration rates are typically less than 0.1 inch per hour. Perched
groundwater, which can limit infiltration, also develops in till soils during wet season at
the transition from weathered to unweathered soils.
The site is also underlain by a surficial layer of fill. Fill soils are not suitable for infiltration
due to their variable nature and the potential for them to consolidate we wetted, changing
their infiltration characteristics over time.
In summary, it is our opinion that non-infiltration alternatives should be considered to
manage the surface runoff at the site.
5.0 GEOTECHNICAL RECOMMENDATIONS
5.1 SEISMIC DESIGN PARAMETERS
The 2015 International Building Code (IBC) seismic design section provides a basis for
seismic design of structures. Table 1 below provides seismic design parameters for the site
that are in conformance with the 2015 IBC, which specifies a design earthquake having a
2% probability of occurrence in 50 years (return interval of 2,475 years), and the 2008
USGS seismic hazard maps.
Geotechnical Report
Proposed Retail Development: Benson Drive S and SE Petrovitsky Road, Renton, WA
May 13, 2019
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Table 1 – Seismic Design Parameters
The spectral response accelerations were obtained from the USGS Earthquake Hazards
Program Interpolated Probabilistic Ground Motion website (2008 data) for the project
latitude and longitude.
Liquefaction Potential: Liquefaction is a process that can occur when soils lose shear
strength for short periods of time during a seismic event. Ground shaking of sufficient
strength and duration results in the loss of grain-to-grain contact and an increase in pore
water pressure, causing the soil to behave as a fluid. Soils with a potential for liquefaction
are typically cohesionless, predominately silt and sand sized, must be loose, and be below
the groundwater table. The site is predominantly underlain by very dense silty sand with
gravel and hard sandy silt without a defined groundwater table. Based on these conditions,
in our opinion the liquefaction potential of the site is negligible and design considerations
related to soil liquefaction are not necessary for this project.
5.2 BUILDING FOUNDATIONS
Based on the subsurface conditions encountered at the site and our understanding of the
planned development, it is our opinion the proposed buildings may be supported on
conventional footings. The footings should bear on the medium dense to very dense,
undisturbed native soil below the fill, or on properly compacted structural fill placed on
undisturbed native soil.
We encountered up to about 4½ feet of fill at our test boring locations. If fill is encountered
at the foundation subgrade elevation, the fill should be overexcavated and replaced with
properly compacted structural fill. The overexcavation width should extend at least one
foot beyond the width of the foundation elements.
Site
Class
Spectral
Acceleration
at 0.2 sec.
[g]
SS
Spectral
Acceleration
at 1.0 sec.
[g]
S1
Site
Coefficients
Design Spectral
Response
Parameters
Control Periods
[sec.]
Fa Fv SDS SD1 TO TS
C 1.396 0.520 1.000 1.300 0.931 0.451 0.096 0.484
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Exterior foundation elements should be placed at a minimum depth of 18 inches below
final exterior grade. Interior spread foundations should be placed at a minimum depth of
12 inches below the top of concrete slabs.
A maximum allowable soil bearing pressure of 3,000 pounds per square foot (psf) should
be used for sizing foundation elements bearing on dense to very dense native soil, or on
structural fill. PanGEO should be retained to determine the adequacy of footing subgrade
during construction.
The recommended allowable soil bearing pressure is for dead plus live loads. For
allowable stress design, the recommended bearing pressure may be increased by one-third
for transient loading, such as wind or seismic forces. Continuous and individual spread
footings should have minimum widths of 18 and 24 inches, respectively.
Footings designed and constructed in accordance with the above recommendations should
experience total settlement of less than one inch and differential settlement of less than ½
inch. Most of the anticipated settlement should occur during construction as dead loads
are applied.
5.2.1 Lateral Resistance
Lateral loads on the structure may be resisted by passive earth pressure developed against
the embedded portion of the foundation system and by frictional resistance between the
bottom of the foundation and the supporting subgrade soils. For footings bearing on the
dense to very dense silty sand, a frictional coefficient of 0.35 may be used to evaluate
sliding resistance developed between the concrete and the subgrade soil. Passive soil
resistance may be calculated using an equivalent fluid weight of 350 pcf, assuming
foundations are backfilled with structural fill. The above values include a factor of safety
of 1.5. Unless covered by pavements or slabs, the passive resistance in the upper 12 inches
of soil should be neglected.
5.2.2 Perimeter Footing Drains
Footing drains should be installed around the perimeter of the buildings, at or just below
the invert of the footings. Under no circumstances should roof downspout drain lines be
connected to the footing drain systems. Roof downspouts must be separately tightlined to
appropriate discharge locations. Cleanouts should be installed at strategic locations to
allow for periodic maintenance of the footing drain and downspout tightline systems.
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May 13, 2019
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5.2.3 Footing Subgrade Preparation
At our boring locations, we encountered 2½ to 4½ feet of fill. The fill is variable and would
not be suitable for direct support of foundation loads. If fill is encountered at the foundation
subgrade elevation, the fill should be overexcavated and replaced with structural fill. The
overexcavation width should extend at least one half the overexcavation depth beyond the
width of the foundation elements.
All footing subgrade should be properly prepared and in a dense and unyielding condition
prior to setting forms and placing reinforcing steel. Any loose or softened soil should be
removed from the footing excavations. The adequacy of the footing subgrade soils should
be verified by a representative of PanGEO, prior to placing forms or rebar.
5.3 FLOORS SLABS
The floor slabs for the proposed building may be constructed using conventional concrete
slab-on-grade floor construction. The floor slab should be supported on competent native
soil or on structural fill. Any over-excavations, if needed, should be backfilled with
structural fill.
If the existing fill is encountered in slab-on-grade areas, the fill should be removed to a
depth of 12 inches below the capillary break, the surface compacted to the requirements of
structural fill, and the grade restored using structural fill.
Interior concrete slab-on-grade floors should be underlain by a capillary break consisting
of at least of 4 inches of pea gravel or compacted ¾-inch, clean crushed rock (less than 3
percent fines). The capillary break material should meet the gradational requirements
provided in Table 2, next page.
Table 2 – Capillary Break Gradation
The capillary break should be placed on the subgrade that has been compacted to a dense
and unyielding condition.
Sieve Size Percent Passing
¾-inch 100
No. 4 0 – 10
No. 100 0 – 5
No. 200 0 – 3
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A 10-mil polyethylene vapor barrier should also be placed directly below the slab.
Construction joints should be incorporated into the floor slab to control cracking.
5.4 RETAINING WALL DESIGN PARAMETERS
Retaining walls, if needed, should be designed to resist the lateral earth pressures exerted
by the soils behind the wall. Proper drainage provisions should also be provided behind
the walls to intercept and remove groundwater that may be present behind the wall. Our
geotechnical recommendations for the design and construction of retaining walls are
presented below.
5.4.1 Lateral Earth Pressures
Cantilever walls should be designed for an equivalent fluid pressure of 35 pcf for a level
backfill condition behind the walls assuming the walls are free to rotate. If the walls are
restrained at the top from free movement, such as basement walls with a floor diaphragm,
an equivalent fluid pressure of 45 pcf should be used for a level backfill condition behind
the walls. Permanent walls should be designed for an additional uniform lateral pressure
of 7H psf for seismic loading, where H corresponds to the buried depth of the wall.
The recommended lateral pressures assume the backfill behind the walls consists of a free
draining and properly compacted fill with adequate drainage provisions.
5.4.2 Surcharge
Surcharge loads, where present, should also be included in the design of retaining walls.
We recommend a lateral load coefficient of 0.3 be used to compute the lateral pressure on
the wall face resulting from surcharge loads located within a horizontal distance of one-
half the wall height.
5.4.3 Lateral Resistance
Lateral forces from seismic loading and unbalanced lateral earth pressures may be resisted
by a combination of passive earth pressures acting against the embedded portions of the
foundations and by friction acting on the base of the wall foundation. Passive resistance
values may be determined using an equivalent fluid weight of 350 pcf. This value includes
a factor of safety of 1.5, assuming the footing is backfilled with structural fill. A friction
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coefficient of 0.35 may be used to determine the frictional resistance at the base of the
footings. The coefficient includes a factor of safety of 1.5.
5.4.4 Wall Drainage
Provisions for wall drainage should consist of a 4-inch diameter perforated drainpipe
placed behind and at the base of the wall footings, embedded in 12 to 18 inches of clean
crushed rock or pea gravel wrapped with a layer of filter fabric. A minimum 18-inch wide
zone of free draining granular soils (i.e. pea gravel or washed rock) is recommended to be
placed adjacent to the wall for the full height of the wall. Alternatively, a composite
drainage material, such as Miradrain 6000, may be used in lieu of the clean crushed rock
or pea gravel. The drainpipe at the base of the wall should be graded to direct water to a
suitable outlet.
5.4.5 Wall Backfill
Wall backfill should consist of imported, free draining granular material or a soil meeting
the requirements of Gravel Borrow as defined in Section 9-03.14(1) of the WSDOT
Standard Specifications for Road, Bridge, and Municipal Construction (WSDOT 2014).
In areas where space is limited between the wall and the face of excavation, pea gravel may
be used as backfill without compaction.
In our opinion, the predominately silty sand and sandy silt soils underlying the site are not
suitable for use as wall backfill.
Wall backfill should be moisture conditioned to within about 3 percent of optimum
moisture content, placed in loose, horizontal lifts less than 8 inches in thickness, and
systematically compacted to a dense and relatively unyielding condition and to at least 95
percent of the maximum dry density, as determined using test method ASTM D1557.
Within 5 feet of the wall, the backfill should be compacted with hand-operated equipment
to at least 90 percent of the maximum dry density.
5.5 PERMANENT CUT AND FILL SLOPES
Based on the anticipated soil that will be exposed in the planned excavation, we
recommend permanent cut and fill slopes be constructed no steeper than 2H:1V
(Horizontal:Vertical).
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6.0 EARTHWORK CONSIDERATIONS
6.1 STRIPPING, CLEARING AND SUBGRADE PREPARATION
Foundation and pavement areas, and areas to receive structural fill, should be stripped and
cleared of surface vegetation, organic matter, existing pavements, and other deleterious
materials. In no case should stripped materials be used as structural fill nor should they be
mixed with materials to be used as structural fill. Outside of construction areas, the existing
site pavement may be left in-place to provide an all-weather construction surface.
In areas where existing foundations, slab-on-grade floors, and pavements are removed, it may
be possible to crush the existing materials for re-use as structural fill. Materials reclaimed by
crushing to be re-used as structural fill should have a maximum particle size of four inches
and should be mixed with soil to provide a well-graded fill material.
Existing underground utilities to be abandoned should be plugged or removed so they do not
provide a conduit for water and cause soil saturation and stability problems.
Following the stripping operation and excavations necessary to achieve construction
subgrade elevations, the ground surface where structural fill, or pavements are to be placed
should be observed by PanGEO. Proofrolling using a fully loaded dump truck should be
performed to identify soft or unstable areas.
Soft or yielding areas identified during proofrolling should be moisture conditioned as
needed and re-compacted in place. If soft areas are still yielding after re-compaction, they
should be overexcavated and replaced with structural fill to a depth that will provide a stable
pavement base. The optional use of a geotextile subgrade stabilization fabric, such as
Mirafi 600X, or an equivalent product placed directly on the over-excavated surface may
help to bridge excessively unstable areas.. Overexcavated areas should be and backfilled
with WSDOT 9-03.9(3) Crushed Surfacing Base Course, or WSDOT 9-03.14 (1) Gravel
Borrow (WSDOT, 2018) compacted to the requirements of structural fill. The subgrade
preparation should be observed by an individual experienced with earthwork construction,
to verify the adequacy of the prepared subgrade.
6.2 PERCHED SEEPAGE CONTROL
Perched groundwater was encountered in our borings at four to eleven feet below grade.
The seepage encountered appeared to be perched and likely develops during the wet
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season. Groundwater seepage may be encountered in site excavations, especially deep
excavations, such as for underground utility trenches.
Where seepage is encountered, the base of the excavation should be sloped to one or more
shallow sump pits. The collected water can then be pumped from these pits to a positive
and permanent discharge point. The spacing of the sumps should be determined during
construction based on field observations at the time of construction.
Where loose soils are encountered in conjunction with groundwater seepage the excavation
subgrade bottom may become soft. In these areas, remedial measures such as
overexcavating soft soils or tamping quarry spalls into the base of the excavation may be
required.
6.3 TEMPORARY EXCAVATIONS AND SHORING
Temporary excavations should be constructed in accordance with Part N of WAC
(Washington Administrative Code) 296-155. The contractor is responsible for maintaining
safe excavation slopes and/or shoring. It is our opinion temporary excavations in the fill
soils and underlying native soils may be cut at a maximum 1H:1V inclination.
Temporary excavations should be evaluated in the field during construction based on actual
observed soil conditions. If seepage is encountered, excavation slope inclinations may
need to be reduced. During wet weather, the temporary slopes may need to be flattened to
reduce potential erosion or should be covered with plastic sheeting.
6.4 MATERIAL REUSE
The native soils underlying the site are moisture sensitive, and will become disturbed and
soft when exposed to inclement weather conditions. We do not recommend reusing the
native soils as structural fill. If it is planned to use the native soil in non-structural areas,
the excavated soil should be stockpiled and protected with plastic sheeting to prevent it
from becoming saturated by precipitation or runoff.
6.5 STRUCTURAL FILL AND COMPACTION
Structural fill, should be free of organic and inorganic debris, be near the optimum moisture
content and be capable of being compacted to the recommendations provided below. The
site soils are relatively fine grained and, in our opinion will not be suitable for re-use as
structural fill and an imported structural fill will be needed. Fill for use during wet weather
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should consist of a well graded soil free of organic material with less than 5 percent fines
(silt and clay sized particles passing the U.S. 200 sieve).
Structural fill should be moisture conditioned to within about 3 percent of optimum
moisture content, placed in loose, horizontal lifts less than 8 inches in thickness, and
compacted to at least 95 percent maximum density, determined using ASTM D1557
(Modified Proctor). The procedure to achieve proper density of a compacted fill depends
on the size and type of compacting equipment, the number of passes, thickness of the lifts
being compacted, and certain soil properties. If the excavation to be backfilled is
constricted and limits the use of heavy equipment, smaller equipment can be used, but the
lift thickness will need to be reduced to achieve the required relative compaction.
Generally, loosely compacted soils are a result of poor construction technique or improper
moisture content. Soils with high fines contents are particularly susceptible to becoming
too wet and coarse-grained materials easily become too dry, for proper compaction. Silty
or clayey soils with a moisture content too high for adequate compaction should be dried
as necessary, or moisture conditioned by mixing with drier materials, or other methods.
6.6 WET WEATHER CONSTRUCTION
The wet season in Western Washington typically extends from October through May.
Earthwork during the wet season requires planning and may require the use of imported
wet weather fill materials that can increase earthwork costs. General recommendations
relative to earthwork performed in wet weather or in wet conditions are presented below.
The following procedures are best management practices recommended for use in wet
weather construction:
• Earthwork should be performed in small areas to minimize subgrade exposure
to wet weather. Excavation or the removal of unsuitable soil should be followed
promptly by the placement and compaction of clean structural fill. The size and
type of construction equipment used may have to be limited to prevent soil
disturbance.
• During wet weather, the allowable fines content of the structural fill should be
reduced to no more than 5 percent by weight based on the portion passing the
0.75-inch sieve. The fines should be non-plastic.
Geotechnical Report
Proposed Retail Development: Benson Drive S and SE Petrovitsky Road, Renton, WA
May 13, 2019
19-122 Benson Drive and Petrovitsky Road Page 15 PanGEO, Inc.
• The ground surface within the construction area should be graded to promote
run-off of surface water and to prevent the ponding of water.
• Geotextile silt fences should be installed at strategic locations around the site to
control erosion and the movement of soil.
• Excavation slopes and soils stockpiled on site should be covered with plastic
sheeting.
6.7 EROSION CONSIDERATIONS
Surface runoff can be controlled during construction by careful grading practices.
Typically, this includes the construction of shallow, upgrade perimeter ditches or low
earthen berms in conjunction with silt fences to collect runoff and prevent water from
entering excavations or to prevent runoff from the construction area leaving the immediate
work site. Temporary erosion control may require the use of hay bales on the downhill
side of the project to prevent water from leaving the site and potential storm water detention
to trap sand and silt before the water is discharged to a suitable outlet. All collected water
should be directed under control to a positive and permanent discharge system.
Permanent control of surface water should be incorporated in the final grading design.
Adequate surface gradients and drainage systems should be incorporated into the design
such that surface runoff is collected and directed away from the structure to a suitable
outlet. Potential issues associated with erosion may also be reduced by establishing
vegetation within disturbed areas immediately following grading operations.
Geotechnical Report
Proposed Retail Development: Benson Drive S and SE Petrovitsky Road, Renton, WA
May 13, 2019
19-122 Benson Drive and Petrovitsky Road Page 16 PanGEO, Inc.
7.0 ADDITIONAL SERVICES
To confirm that our recommendations are properly incorporated into the design and
construction of the proposed development, PanGEO should be retained to conduct a review
of the final project plans and specifications, and to monitor the construction of geotechnical
elements. PanGEO can provide you a cost estimate for construction monitoring services
at a later date.
8.0 CLOSURE
We have prepared this report for TA Renton BP, LLC and the project design team.
Recommendations contained in this report are based on a site reconnaissance, a subsurface
exploration program, review of pertinent subsurface information, and our understanding of
the project. The study was performed using a mutually agreed-upon scope of services.
Variations in soil conditions may exist between the locations of the explorations and the
actual conditions underlying the site. The nature and extent of soil variations may not be
evident until construction occurs. If any soil conditions are encountered at the site that are
different from those described in this report, we should be notified immediately to review
the applicability of our recommendations. Additionally, we should also be notified to
review the applicability of our recommendations if there are any changes in the project
scope.
The scope of our work does not include services related to construction safety precautions.
Our recommendations are not intended to direct the contractors’ methods, techniques,
sequences or procedures, except as specifically described in our report for consideration in
design. Additionally, the scope of our services specifically excludes the assessment of
environmental characteristics, particularly those involving hazardous substances. We are
not mold consultants nor are our recommendations to be interpreted as being preventative
of mold development. A mold specialist should be consulted for all mold-related issues.
This report has been prepared for planning and design purposes for specific application to
the proposed project in accordance with the generally accepted standards of local practice
at the time this report was written. No warranty, express or implied, is made.
This report may be used only by the client and for the purposes stated, within a reasonable
time from its issuance. Land use, site conditions (both off and on-site), or other factors
Geotechnical Report
Proposed Retail Development: Benson Drive S and SE Petrovitsky Road, Renton, WA
May 13, 2019
19-122 Benson Drive and Petrovitsky Road Page 17 PanGEO, Inc.
including advances in our understanding of applied science, may change over time and
could materially affect our findings. Therefore, this report should not be relied upon after
24 months from its issuance. PanGEO should be notified if the project is delayed by more
than 24 months from the date of this report so that we may review the applicability of our
conclusions considering the time lapse.
It is the client’s responsibility to see that all parties to this project, including the designer,
contractor, subcontractors, etc., are made aware of this report in its entirety. The use of
information contained in this report for bidding purposes should be done at the contractor’s
option and risk. Any party other than the client who wishes to use this report shall notify
PanGEO of such intended use and for permission to copy this report. Based on the intended
use of the report, PanGEO may require that additional work be performed and that an
updated report be reissued. Noncompliance with any of these requirements will release
PanGEO from any liability resulting from the use this report.
Sincerely,
PanGEO, Inc.
Scott D. Dinkelman, LEG, LHG Siew L Tan, P.E.
Senior Engineering Geologist Principal Geotechnical Engineer
Geotechnical Report
Proposed Retail Development: Benson Drive S and SE Petrovitsky Road, Renton, WA
May 13, 2019
19-122 Benson Drive and Petrovitsky Road Page 18 PanGEO, Inc.
9.0 REFERENCES
International Code Council, 2015, International Building Code (IBC), 2015.
Mullineaux, D.R., 1965, Geologic Map of the Renton Quadrangle, King County,
Washington – U.S. Geological Survey Geologic, Quadrangle Map GQ-405, scale
1:24,000.
Schuster, J.E., Cabibbo, A.A., Schilter, J.F., and Hubert I.J., 2015, Geologic Map of the
Tacoma 1:100,000-scale Quadrangle, Washington – Washington Division of Geology
and Earth Resources, Map Series 2015-03, scale 1:100,000.
WSDOT, 2018, Standard Specifications for Road, Bridge and Municipal Construction, M
41-10.
Figure No.Project No.19-122
Proposed Retail Development
Benson Drive South and
Southeast Petrovitsky Road
Renton, WA 1
Base Map: Google Maps
VICINITY MAP
Approx. Scale:
Not to Scale
19-122 Fig 1 - Vicinity Map.grf 4/30/19 (14:00) SPS
Project No. Figure No.SITE AND EXPLORATION PLAN19-122219-122 Fig 2 Site & Exploration Plan.grf 5/9/19 SPSLEGEND:Approx. Scale(feet)Note: Site plan modified from ALTA/NSPS Land Title Survey, prepared by Terrane dated January 11, 2019Proposed Retail DevelopmentBenson Drive South andSoutheast Petrovitsky RoadRenton, WAApproximate Boring Locations,PanGEO, Inc., April 2019(Approximate Thickness of Fill)Approximate ProposedDevelopments
APPENDIX A
BORING LOGS
MOISTURE CONTENT
2-inch OD Split Spoon, SPT
(140-lb. hammer, 30" drop)
3.25-inch OD Spilt Spoon
(300-lb hammer, 30" drop)
Non-standard penetration
test (see boring log for details)
Thin wall (Shelby) tube
Grab
Rock core
Vane Shear
Dusty, dry to the touch
Damp but no visible water
Visible free water
Terms and Symbols for
Boring and Test Pit Logs
Density
SILT / CLAY
GRAVEL (<5% fines)
GRAVEL (>12% fines)
SAND (<5% fines)
SAND (>12% fines)
Liquid Limit < 50
Liquid Limit > 50
Breaks along defined planes
Fracture planes that are polished or glossy
Angular soil lumps that resist breakdown
Soil that is broken and mixed
Less than one per foot
More than one per foot
Angle between bedding plane and a planenormaltocoreaxis
Very Loose
Loose
Med. Dense
Dense
Very Dense
SPT
N-values
Approx. Undrained Shear
Strength (psf)
<4
4 to 10
10 to 30
30 to 50
>50
<2
2 to 4
4 to 8
8 to 15
15 to 30
>30
SPT
N-values
Units of material distinguished by color and/orcomposition frommaterial unitsabove andbelow
Layers of soil typically 0.05 to 1mm thick, max. 1 cm
Layer of soil that pinches out laterally
Alternating layers of differing soil material
Erratic, discontinuous deposit of limited extent
Soil with uniform color and composition throughout
Approx. Relative
Density (%)
Gravel
Layered:
Laminated:
Lens:
Interlayered:
Pocket:
Homogeneous:
Highly Organic Soils
#4 to #10 sieve (4.5 to 2.0 mm)
#10 to #40 sieve (2.0 to 0.42 mm)
#40 to #200 sieve (0.42 to 0.074 mm)
0.074 to 0.002 mm
<0.002 mm
UNIFIED SOIL CLASSIFICATION SYSTEM
MAJOR DIVISIONS GROUP DESCRIPTIONS
Notes:
MONITORING WELL
<15
15 - 35
35 - 65
65 - 85
85 - 100
GW
GP
GM
GC
SW
SP
SM
SC
ML
CL
OL
MH
CH
OH
PT
TEST SYMBOLS
50%or more passing #200 sieve
Groundwater Level at time of drilling (ATD)Static Groundwater Level
Cement / Concrete Seal
Bentonite grout / seal
Silica sand backfill
Slotted tip
Slough
<250
250 - 500
500 - 1000
1000 - 2000
2000 - 4000
>4000
RELATIVE DENSITY / CONSISTENCY
Fissured:
Slickensided:
Blocky:
Disrupted:
Scattered:
Numerous:
BCN:
COMPONENT DEFINITIONS
Dry
Moist
Wet
1. Soil exploration logs contain material descriptions based on visual observation and field tests using a systemmodified from the Uniform Soil Classification System (USCS). Where necessary laboratory tests have beenconducted (as noted in the "Other Tests" column), unit descriptions may include a classification. Please refer to thediscussions in the report text for a more complete description of the subsurface conditions.
2. The graphic symbols given above are not inclusive of all symbols that may appear on the borehole logs.Other symbols may be used where field observations indicated mixed soil constituents or dual constituent materials.
COMPONENT SIZE / SIEVE RANGE COMPONENT SIZE / SIEVE RANGE
SYMBOLS
Sample/In Situ test types and intervals
Silt and Clay
Consistency
SAND / GRAVEL
Very Soft
Soft
Med. Stiff
Stiff
Very Stiff
Hard
Phone: 206.262.0370
Bottom of BoringBoulder:
Cobbles:
Gravel
Coarse Gravel:
Fine Gravel:
Sand
Coarse Sand:
Medium Sand:
Fine Sand:
Silt
Clay
> 12 inches
3 to 12 inches
3 to 3/4 inches
3/4 inches to #4 sieve
Atterberg Limit Test
Compaction Tests
Consolidation
Dry Density
Direct Shear
Fines Content
Grain Size
Permeability
Pocket Penetrometer
R-value
Specific Gravity
Torvane
Triaxial Compression
Unconfined Compression
Sand
50% or more of the coarse
fraction passing the #4 sieve.
Use dual symbols (eg. SP-SM)
for 5% to 12% fines.
for In Situ and Laboratory Testslisted in "Other Tests" column.
50% or more of the coarse
fraction retained on the #4
sieve. Use dual symbols (eg.
GP-GM) for 5% to 12% fines.
DESCRIPTIONS OF SOIL STRUCTURES
Well-graded GRAVEL
Poorly-graded GRAVEL
Silty GRAVEL
Clayey GRAVEL
Well-graded SAND
Poorly-graded SAND
Silty SAND
Clayey SAND
SILT
Lean CLAY
Organic SILT or CLAY
Elastic SILT
Fat CLAY
Organic SILT or CLAY
PEAT
ATT
Comp
Con
DD
DS
%F
GS
Perm
PP
R
SG
TV
TXC
UCC
LOG KEY 09-118 LOG.GPJ PANGEO.GDT 11/12/13Figure A-1
Terms and Symbols for
Boring and Test Pit Logs
Phone: 206.262.0370LOG KEY 09-118 LOG.GPJ PANGEO.GDT 11/12/13Figure A-1a
- Approximately 4 inches of asphalt over gravel.
Medium dense, moist, brown, silty SAND; trace gravel and cobbles.
[FILL].
- Inflated blows due to cobble at approximately 2.5 feet.
Medium dense to dense, wet to very moist, grey brown to light brown,
silty fine SAND; trace gravel, trace iron-oxide staining.
- Groundwater at approximately 5 feet during drilling.
[WEATHERED VASHON TILL - Qgt].
Hard, very moist to moist, grey-brown to blue-grey, sandy SILT; trace
gravel, trace iron oxide staining in fragments.
- Relative Weathering: Residual Soil RVI.
[RESIDUAL SOIL/RENTON FORMATION - Ec2pg].
- Gravel-sized coal fragments.
- Relative Weathering: Slightly Weathered RII.
Boring terminated at about 13.5 feet below grade. Groundwater
observed at about 5 feet at time of drilling.
S-1
S-2
S-3
S-4
S-5
31
22
24
8
9
9
19
32
50/6
19
41
50/2
45
50/6
Remarks: Borings drilled using an EC 95 track mounted drill rig. Standard penetration test
(SPT) sampler driven with a 140 lb safety hammer. Hammer operated with a rope and
cathead mechanism. Surface elevations (NAVD88) estimated from ALTA/NSPS Land
Title Survey by Terrane dated January 11, 2019.
0
2
4
6
8
10
12
14
16
18
20
The stratification lines represent approximate boundaries. The transition may be gradual.
MATERIAL DESCRIPTION
Figure A-2Other TestsSample No.Completion Depth:
Date Borehole Started:
Date Borehole Completed:
Logged By:
Drilling Company:Depth, (ft)Proposed Retail Development
19-122
Benson Drive South and Southeast Petrovitsky, Renton, WA
Northing: , Easting:
13.5ft
4/23/19
4/23/19
S. Scott
Boretec 1
Sheet 1 of 1
Project:
Job Number:
Location:
Coordinates:SymbolSample TypeBlows / 6 in.~ 404 ft
N/A
HSA
SPT
Surface Elevation:
Top of Casing Elev.:
Drilling Method:
Sampling Method:
LOG OF TEST BORING PG-1
N-Value
0
Moisture LL
50
PL
RQD Recovery
100
>>
>>
>>
- Approximately 5 inches of asphalt over gravel.
Medium dense, moist, brown, silty SAND; trace gravel.
[WEATHERED VASHON TILL - Qgt].
- Perched groundwater at approximately 4 feet.
Medium dense, wet to very moist, blue-grey, silty fine SAND; trace
gravel.
- Hydrocarbon odor in Sample S-2.
Very dense, moist, light brown, silty fine SAND; trace gravel, trace
iron-oxide staining in gravel.
- Perched groundwater at approximately 11 feet.
Hard, moist, light grey, sandy SILT; trace gravel, laminated, trace
iron-oxide staining.
[RESIDUAL SOIL/RENTON FORMATION - Ec2pg].
- Gravel-sized coal fragments.
- Relative Weathering: Residual Soil RVI.
- Coarse sand pocket at approximately 13 feet.
Boring terminated at about 13.3 feet below grade. Perched
groundwater observed at about 4 feet and 11 feet at time of drilling.
S-1
S-2
S-3
S-4
S-5
8
8
7
4
4
7
18
23
34
24
25
50/5
37
50/4
Remarks: Borings drilled using an EC 95 track mounted drill rig. Standard penetration test
(SPT) sampler driven with a 140 lb safety hammer. Hammer operated with a rope and
cathead mechanism. Surface elevations (NAVD88) estimated from ALTA/NSPS Land
Title Survey by Terrane dated January 11, 2019.
0
2
4
6
8
10
12
14
16
18
20
The stratification lines represent approximate boundaries. The transition may be gradual.
MATERIAL DESCRIPTION
Figure A-3Other TestsSample No.Completion Depth:
Date Borehole Started:
Date Borehole Completed:
Logged By:
Drilling Company:Depth, (ft)Proposed Retail Development
19-122
Benson Drive South and Southeast Petrovitsky, Renton, WA
Northing: , Easting:
13.3ft
4/23/19
4/23/19
S. Scott
Boretec 1
Sheet 1 of 1
Project:
Job Number:
Location:
Coordinates:SymbolSample TypeBlows / 6 in.~ 402 ft
N/A
HSA
SPT
Surface Elevation:
Top of Casing Elev.:
Drilling Method:
Sampling Method:
LOG OF TEST BORING PG-2
N-Value
0
Moisture LL
50
PL
RQD Recovery
100
>>
>>
- Approximately 6 inches of topsoil, concrete rubble near surface.
Medium dense, very moist to wet, brown to grey-brown, silty fine to
medium SAND; trace gravel, iron-oxide staining.
[WEATHERED VASHON TILL - Qgt].
- Perched groundwater at approximately 6 feet.
Hard, moist, light grey, sandy SILT; trace gravel, laminated.
[RESIDUAL SOIL/RENTON FORMATION - Ec2pg].
- Sand-sized coal fragments.
- Relative Weathering: Residual Soil RVI.
Boring terminated at about 15.9 feet below grade. Perched
groundwater observed at about 6 feet at time of drilling.
S-1
S-2
S-3
S-4
S-5
2
6
11
5
7
10
7
12
13
4
6
10
31
50/3
Remarks: Borings drilled using an EC 95 track mounted drill rig. Standard penetration test
(SPT) sampler driven with a 140 lb safety hammer. Hammer operated with a rope and
cathead mechanism. Surface elevations (NAVD88) estimated from ALTA/NSPS Land
Title Survey by Terrane dated January 11, 2019.
0
2
4
6
8
10
12
14
16
18
20
The stratification lines represent approximate boundaries. The transition may be gradual.
MATERIAL DESCRIPTION
Figure A-4Other TestsSample No.Completion Depth:
Date Borehole Started:
Date Borehole Completed:
Logged By:
Drilling Company:Depth, (ft)Proposed Retail Development
19-122
Benson Drive South and Southeast Petrovitsky, Renton, WA
Northing: , Easting:
15.9ft
4/23/19
4/23/19
S. Scott
Boretec 1
Sheet 1 of 1
Project:
Job Number:
Location:
Coordinates:SymbolSample TypeBlows / 6 in.~ 408 ft
N/A
HSA
SPT
Surface Elevation:
Top of Casing Elev.:
Drilling Method:
Sampling Method:
LOG OF TEST BORING PG-3
N-Value
0
Moisture LL
50
PL
RQD Recovery
100
>>
- Approximately 6 inches of topsoil, concrete rubble near surface.
Medium dense, very moist, grey to light brown, silty fine to medium
SAND; trace gravel.
[WEATHERED VASHON TILL - Qgt].
Medium dense to dense, very moist to wet, brown to grey-brown, silty
fine SAND with gravel; trace coarse sand pockets, laminated,
iron-oxide staining in gravels.
- Perched groundwater at approximately 9 feet.
Boring terminated at about 11.5 feet below grade. Perched
groundwater observed at about 9 feet at time of drilling.
S-1
S-2
S-3
S-4
2
9
12
8
7
7
8
6
6
9
15
32
Remarks: Borings drilled using an EC 95 track mounted drill rig. Standard penetration test
(SPT) sampler driven with a 140 lb safety hammer. Hammer operated with a rope and
cathead mechanism. Surface elevations (NAVD88) estimated from ALTA/NSPS Land
Title Survey by Terrane dated January 11, 2019.
0
2
4
6
8
10
12
14
16
18
20
The stratification lines represent approximate boundaries. The transition may be gradual.
MATERIAL DESCRIPTION
Figure A-5Other TestsSample No.Completion Depth:
Date Borehole Started:
Date Borehole Completed:
Logged By:
Drilling Company:Depth, (ft)Proposed Retail Development
19-122
Benson Drive South and Southeast Petrovitsky, Renton, WA
Northing: , Easting:
11.5ft
4/23/19
4/23/19
S. Scott
Boretec 1
Sheet 1 of 1
Project:
Job Number:
Location:
Coordinates:SymbolSample TypeBlows / 6 in.~ 408 ft
N/A
HSA
SPT
Surface Elevation:
Top of Casing Elev.:
Drilling Method:
Sampling Method:
LOG OF TEST BORING PG-4
N-Value
0
Moisture LL
50
PL
RQD Recovery
100
- Approximately 5 inches of asphalt over gravel.
Very loose, moist, grey to orange-brown, GRAVEL with silt; trace
iron-oxide staining.
[FILL].
Medium dense, very moist to wet, light brown to light-grey, silty fine
SAND; trace gravel, coarse sand pockets.
- Perched groundwater at approximately 5 feet.
[WEATHERED VASHON TILL - Qgt].
Hard, moist, grey-brown, sandy SILT; trace gravel, iron-oxide staining
in gravel.
[RESIDUAL SOIL/RENTON FORMATION - Ec2pg].
- Sand-sized coal fragments.
- Relative Weathering: Residual Soil RVI.
Boring terminated at about 11.5 feet below grade. Perched
groundwater observed at about 5 feet at time of drilling.
S-1
S-2
S-3
S-4
3
1
3
6
6
7
5
6
8
17
20
22
Remarks: Borings drilled using an EC 95 track mounted drill rig. Standard penetration test
(SPT) sampler driven with a 140 lb safety hammer. Hammer operated with a rope and
cathead mechanism. Surface elevations (NAVD88) estimated from ALTA/NSPS Land
Title Survey by Terrane dated January 11, 2019.
0
2
4
6
8
10
12
14
16
18
20
The stratification lines represent approximate boundaries. The transition may be gradual.
MATERIAL DESCRIPTION
Figure A-6Other TestsSample No.Completion Depth:
Date Borehole Started:
Date Borehole Completed:
Logged By:
Drilling Company:Depth, (ft)Proposed Retail Development
19-122
Benson Drive South and Southeast Petrovitsky, Renton, WA
Northing: , Easting:
11.5ft
4/23/19
4/23/19
S. Scott
Boretec 1
Sheet 1 of 1
Project:
Job Number:
Location:
Coordinates:SymbolSample TypeBlows / 6 in.~ 407 ft
N/A
HSA
SPT
Surface Elevation:
Top of Casing Elev.:
Drilling Method:
Sampling Method:
LOG OF TEST BORING PG-5
N-Value
0
Moisture LL
50
PL
RQD Recovery
100
- Approximately 2 inches of asphalt over gravel.
Very loose, moist, grey to grey-brown, silty SAND; trace gravel, trace
iron-oxide staining.
[WEATHERED VASHON TILL - Qgt].
- Manganese staining.
Medium dense, very moist to wet, grey-brown, silty SAND; trace
gravel, trace iron-oxide staining, slightly laminated.
- Perched groundwater at approximately 6 feet.
Very dense, moist, grey-brown, silty SAND; trace gravel, trace
iron-oxide staining in gravel.
- Large gravel crushed in tip of splitspoon at approximately 10 feet.
Boring terminated at about 11.5 feet below grade. Perched
groundwater observed at about 6 feet at time of drilling.
S-1
S-2
S-3
S-4
4
1
3
6
11
16
31
28
50/5
23
36
36
Remarks: Borings drilled using an EC 95 track mounted drill rig. Standard penetration test
(SPT) sampler driven with a 140 lb safety hammer. Hammer operated with a rope and
cathead mechanism. Surface elevations (NAVD88) estimated from ALTA/NSPS Land
Title Survey by Terrane dated January 11, 2019.
0
2
4
6
8
10
12
14
16
18
20
The stratification lines represent approximate boundaries. The transition may be gradual.
MATERIAL DESCRIPTION
Figure A-7Other TestsSample No.Completion Depth:
Date Borehole Started:
Date Borehole Completed:
Logged By:
Drilling Company:Depth, (ft)Proposed Retail Development
19-122
Benson Drive South and Southeast Petrovitsky, Renton, WA
Northing: , Easting:
11.5ft
4/23/19
4/23/19
S. Scott
Boretec 1
Sheet 1 of 1
Project:
Job Number:
Location:
Coordinates:SymbolSample TypeBlows / 6 in.~ 410 ft
N/A
HSA
SPT
Surface Elevation:
Top of Casing Elev.:
Drilling Method:
Sampling Method:
LOG OF TEST BORING PG-6
N-Value
0
Moisture LL
50
PL
RQD Recovery
100
>>
- Approximately 4 inches of asphalt over gravel.
Medium dense, moist, dark grey to brown, silty SAND; trace gravel.
[FILL].
Medium dense, very moist to wet , grey-brown, silty fine to medium
SAND; trace gravel, coarse sand pockets, trace iron-oxide staining,
slightly laminated.
- Perched groundwater at approximately 5 feet.
[WEATHERED VASHON TILL - Qgt].
Hard, very moist to moist, grey-brown to grey, sandy SILT with gravel;
iron-oxide staining in gravel, slightly laminated.
- Relative Weathering: Residual Soil RVI.
[RESIDUAL SOIL/RENTON FORMATION - Ec2pg].
- Gravel-sized coal fragments.
- Relative Weathering: Highly Weathered RIV.
Boring terminated at about 15.8 feet below grade. Perched
groundwater observed at about 5 feet at time of drilling.
S-1
S-2
S-3
S-4
S-5
8
9
8
5
10
9
5
12
10
14
19
27
29
50/4
Remarks: Borings drilled using an EC 95 track mounted drill rig. Standard penetration test
(SPT) sampler driven with a 140 lb safety hammer. Hammer operated with a rope and
cathead mechanism. Surface elevations (NAVD88) estimated from ALTA/NSPS Land
Title Survey by Terrane dated January 11, 2019.
0
2
4
6
8
10
12
14
16
18
20
The stratification lines represent approximate boundaries. The transition may be gradual.
MATERIAL DESCRIPTION
Figure A-8Other TestsSample No.Completion Depth:
Date Borehole Started:
Date Borehole Completed:
Logged By:
Drilling Company:Depth, (ft)Proposed Retail Development
19-122
Benson Drive South and Southeast Petrovitsky, Renton, WA
Northing: , Easting:
15.8ft
4/23/19
4/23/19
S. Scott
Boretec 1
Sheet 1 of 1
Project:
Job Number:
Location:
Coordinates:SymbolSample TypeBlows / 6 in.~ 409 ft
N/A
HSA
SPT
Surface Elevation:
Top of Casing Elev.:
Drilling Method:
Sampling Method:
LOG OF TEST BORING PG-7
N-Value
0
Moisture LL
50
PL
RQD Recovery
100
>>
- Approximately 5 inches of asphalt over gravel.
Medium dense, moist, grey to grey-brown, silty fine to medium SAND;
trace gravel, iron-oxide staining, appears reworked.
[FILL].
Medium dense, very moist to wet, grey-brown, silty fine to medium
SAND; trace gravel, trace coarse sand pockets, trace iron-oxide
staining, slightly laminated.
[WEATHERED VASHON TILL - Qgt].
- Perched groundwater at approximately 6 feet.
- Perched groundwater at approximately 10 feet.
Hard, very moist, grey-brown to grey, sandy SILT with gravel; trace
coarse sand pockets.
[RESIDUAL SOIL/RENTON FORMATION - Ec2pg].
- Gravel-sized coal fragments.
- Relative Weathering: Residual Soil RVI.
Boring terminated at about 15.8 feet below grade. Perched
groundwater observed at about 6 feet and 10 feet at time of drilling.
S-1
S-2
S-3
S-4
S-5
7
11
14
8
6
6
10
10
10
5
6
6
30
50/4
Remarks: Borings drilled using an EC 95 track mounted drill rig. Standard penetration test
(SPT) sampler driven with a 140 lb safety hammer. Hammer operated with a rope and
cathead mechanism. Surface elevations (NAVD88) estimated from ALTA/NSPS Land
Title Survey by Terrane dated January 11, 2019.
0
2
4
6
8
10
12
14
16
18
20
The stratification lines represent approximate boundaries. The transition may be gradual.
MATERIAL DESCRIPTION
Figure A-9Other TestsSample No.Completion Depth:
Date Borehole Started:
Date Borehole Completed:
Logged By:
Drilling Company:Depth, (ft)Proposed Retail Development
19-122
Benson Drive South and Southeast Petrovitsky, Renton, WA
Northing: , Easting:
15.8ft
4/23/19
4/23/19
S. Scott
Boretec 1
Sheet 1 of 1
Project:
Job Number:
Location:
Coordinates:SymbolSample TypeBlows / 6 in.~ 411 ft
N/A
HSA
SPT
Surface Elevation:
Top of Casing Elev.:
Drilling Method:
Sampling Method:
LOG OF TEST BORING PG-8
N-Value
0
Moisture LL
50
PL
RQD Recovery
100
>>