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GEOTECHNICAL ENGINEERING REPORT
PREPARED BY:
THE RILEY GROUP, INC.
17522 BOTHELL WAY NORTHEAST
BOTHELL, WASHINGTON 98011
PREPARED FOR:
PATTY SATHER
532 SOUTHWEST 3RD PLACE
RENTON, WASHINGTON 98057
RGI PROJECT NO. 2017-035
SATHER SHORT PLAT
532 SOUTHWEST 3RD PLACE
RENTON, WASHINGTON 98057
APRIL 7, 2017
Geotechnical Engineering Report April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
TABLE OF CONTENTS
1.0 INTRODUCTION ............................................................................................................................... 1
2.0 PROJECT DESCRIPTION .................................................................................................................... 1
3.0 FIELD EXPLORATION AND LABORATORY TESTING ........................................................................... 1
4.0 SITE CONDITIONS ............................................................................................................................ 2
4.1 SURFACE .................................................................................................................................................. 2
4.2 GEOLOGY ................................................................................................................................................. 2
4.3 SOILS ....................................................................................................................................................... 2
4.4 GROUNDWATER ........................................................................................................................................ 2
4.5 SEISMIC CONSIDERATIONS ........................................................................................................................... 3
4.6 GEOLOGIC HAZARD AREAS .......................................................................................................................... 3
5.0 DISCUSSION AND RECOMMENDATIONS ......................................................................................... 4
5.1 GEOTECHNICAL CONSIDERATIONS ................................................................................................................. 4 5.2 EARTHWORK ............................................................................................................................................. 4
5.2.1 Erosion and Sediment Control ..................................................................................................... 4
5.2.2 Stripping ....................................................................................................................................... 5
5.2.3 Excavations................................................................................................................................... 5
5.2.4 Site Preparation ........................................................................................................................... 6
5.2.5 Structural Fill ................................................................................................................................ 7
5.2.6 Cut and Fill Slopes ........................................................................................................................ 9
5.2.7 Rockeries ...................................................................................................................................... 9
5.2.8 Wet Weather Construction Considerations ................................................................................. 9
5.3 FOUNDATIONS .......................................................................................................................................... 9
5.4 RETAINING WALLS ................................................................................................................................... 10
5.5 SLAB-ON-GRADE CONSTRUCTION ............................................................................................................... 11
5.6 DRAINAGE .............................................................................................................................................. 11
5.6.1 Surface ....................................................................................................................................... 11
5.6.2 Subsurface .................................................................................................................................. 11
5.6.3 Infiltration .................................................................................................................................. 12
5.7 UTILITIES ................................................................................................................................................ 12
5.8 PAVEMENTS ............................................................................................................................................ 12
5.9 CONSTRUCTION CONSIDERATIONS ............................................................................................................... 13
6.0 ADDITIONAL SERVICES .................................................................................................................. 13
7.0 LIMITATIONS ................................................................................................................................. 13
LIST OF APPENDICES
Figure 1 ..................................................................................................................... Site Vicinity Map
Figure 2 ............................................................................................... Geotechnical Exploration Plan
Figure 3 ....................................................................................................................... Slope Fill Detail
Figure 4 ............................................................................................................ Typical Rockery Detail
Figure 5 ............................................................................................... Retaining Wall Drainage Detail
Figure 6 ....................................................................................................Typical Footing Drain Detail
Appendix A .......................................................................... Field Exploration and Laboratory Testing
Geotechnical Engineering Report April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
Executive Summary
This Executive Summary should be used in conjunction with the entire GER for design
and/or construction purposes. It should be recognized that specific details were not
included or fully developed in this section, and this GER must be read in its entirety for a
comprehensive understanding of the items contained herein. Section 7.0 should be read
for an understanding of limitations.
RGI’s geotechnical scope of work included the advancement of four test pits to a
maximum depth of 6 feet below ground surface (bgs).
Based on the information obtained from our subsurface exploration, the site is suitable
for development of the proposed project. The following geotechnical considerations were
identified.
Soil Conditions: The site is underlain by 5 feet of fill or surficial soils comprised of loose to
medium dense silty sand with trace organics over very dense sandstone bedrock.
Groundwater: Light groundwater was encountered at 3 and 5 feet bgs in one of the test
pits during our subsurface exploration.
Foundations: The proposed buildings can be supported on spread footing foundation
bearing on native soil, bedrock or structural fill.
Slab-on-grade: Slab-on-grade floors can be supported on dense to medium dense native
soil or new structural fill.
Pavements: The following pavement sections are recommended for new driveway areas:
For flexible pavements: 2 inches of HMA over 6 inches of Crushed Rock Base
(CRB) over compacted subgrade.
For concrete driveways: 5 inches of concrete over 4 inches of CRB over
compacted subgrade
Construction Considerations: RGI recommends that the major earthwork be performed
in dry season from May to September. Rock blasting may be needed during foundation
excavation extending into bedrock.
Geotechnical Engineering Report 1 April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
1.0 Introduction
This Geotechnical Engineering Report (GER) presents the results of the geotechnical
engineering services provided for the Sather Short Plat in Renton, Washington. The
purpose of this GER is to assess subsurface conditions and provide geotechnical
recommendations for short plat an existing tax parcel (King County Parcel #214370-0230)
into 3 single-family residential lots. Our scope of services included field explorations,
laboratory testing, engineering analyses, and preparation of this GER.
The recommendations in the following sections of this GER are based upon our current
understanding of the proposed site development as outlined below. RGI should review
the proposed site grading and utility plans once they are developed in order to confirm
the recommendations provided in this report are appropriate for the development as
proposed. In addition, RGI requests to review the final site grading plans and
specifications when available to verify that our project understanding is correct and that
our recommendations have been properly interpreted and incorporated into the project
design and construction.
2.0 Project Description
The site is located 532 Southwest 3rd Place in Renton, Washington. The approximate
location of the site is shown on Figure 1. The site is currently vacant.
RGI understands that the client plans to divide the existing lot which is about 22,600
square feet into 3 single family residential lots. Our understanding of the project is based
on a site plan provided by the client on February 22, 2017.
RGI expects the proposed residences will be a two-story, light-weight structure with a
maximum column load of less than 100 kips. RGI anticipates that grading with cut/fill less
than 10 feet will be needed to reach the floor elevation. Slab-on-grade floor loading of
150 pounds per square foot (psf) are expected.
3.0 Field Exploration and Laboratory Testing
On March 22, 2017, RGI performed subsurface exploration using an excavator. A total of
four test pits were excavated in the proposed development area. The approximate
exploration locations are shown on Figure 2.
Field logs of each exploration were prepared by the geologist who completed the test
pits. These logs included visual classifications of the materials encountered during
excavation as well as our interpretation of the subsurface conditions between samples.
The boring logs included in Appendix A represent an interpretation of the field logs and
include modifications based on laboratory observation and analysis of the samples.
Geotechnical Engineering Report 2 April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
4.0 Site Conditions
4.1 SURFACE
The site is a rectangular-shaped property totaling about 22,600 square feet. The site is
bound to the north by Southwest 3rd Street, to the east and west by residential
properties, and to the south by Southwest 3rd Place.
The site slopes generally to the south with an overall elevation difference of about 50
feet. The site has been graded with a series of benches extending across the site from
east to west, separated by about 10-foot-high slopes. The site is vegetated with small- to
medium-diameter trees, mixed brush, and blackberry brambles.
4.2 GEOLOGY
Review of the Geologic Map of King County, Washington by Derek B. Booth, etc (2002)
indicates that the site soil is mapped as Tukwila Formation (Map Unit Ept) which is
volcanic breccia, conglomerate, sandstone, and massive volcanic rocks with intercalated
feldspathic sandstone and impure coal beds. Tuff and breccia with clasts of porphyritic
andesite and dacite and polymictic volcanic conglomerate appear to predominate, but
massive volcanic rock from resistant layers. The soil encountered during field exploration
appears to match the description.
4.3 SOILS
The site is underlain by 5 feet of fill or surficial soils comprised of loose to medium dense
silty sand with trace organics over very dense sandstone bedrock. More detailed
descriptions of the subsurface conditions encountered are presented in the test pits are
included in Appendix A.
4.4 GROUNDWATER
Light groundwater was encountered at 3 and 5 feet bgs in test pit TP-1 during our
subsurface exploration. The groundwater appears to be perched over the bedrock and in
the surficial soils.
It should be recognized that fluctuations of the groundwater table will occur due to
seasonal variations in the amount of rainfall, runoff, and other factors not evident at the
time the explorations were performed. In addition, perched water can develop within
seams and layers contained in fill soils or higher permeability soils overlying less
permeable soils following periods of heavy or prolonged precipitation. Therefore,
groundwater levels during construction or at other times in the future may be higher or
lower than the levels indicated on the logs. Groundwater level fluctuations should be
considered when developing the design and construction plans for the project.
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Sather Short Plat, Renton, Washington RGI Project No. 2017-035
4.5 SEISMIC CONSIDERATIONS
Based on the 2012/2015 International Building Code (IBC), RGI recommends the follow
seismic parameters in Table 1 be used for design.
Table 1 IBC Seismic Parameters
2012/2015 IBC Parameter Value
Site Soil Class1 C2
Site Latitude 47.47936 N
Site Longitude 122.22523 W
Maximum considered earthquake spectral response acceleration
parameters (g) Ss = 1.450, S1 = 0.542
Spectral response acceleration parameters adjusted for site class
(g) Sms = 1.450, Sm1 = 0.705
Design spectral response acceleration parameters (g) Sds = 0.967, Sd1 = 0.470
1 Note: In general accordance with the USGS 2012/2015 International Building Code. IBC Site Class is based on the average
characteristics of the upper 100 feet of the subsurface profile.
2 Note: The 2012/2015 International Building Code requires a site soil profile determination extending to a depth of 100 feet for
seismic site classification. The current scope of our services does not include the required 100 foot soil profile determination. Hand
auger borings extended to a maximum depth of 6 feet, and this seismic site class definition considers that hard soil continues below
the maximum depth of the subsurface exploration.
Liquefaction is a phenomenon where there is a reduction or complete loss of soil strength
due to an increase in water pressure induced by vibrations from a seismic event.
Liquefaction mainly affects geologically recent deposits of fine-grained sands that are
below the groundwater table. Soils of this nature derive their strength from intergranular
friction. The generated water pressure or pore pressure essentially separates the soil
grains and eliminates this intergranular friction, thus reducing or eliminating the soil’s
strength.
RGI reviewed the results of the field and laboratory testing and assessed the potential for
liquefaction of the site’s soil during an earthquake in the area. Since the site is underlain
by bedrock, bedrock is considered not liquefiable.
4.6 GEOLOGIC HAZARD AREAS
RGI reviewed the City of Renton Sensitive Areas dated November 12, 2014. The review
indicates that the site is mapped as steep slope area with a slope gradient from 15 to 25
percent and high landslide hazard area.
On March 22, 2017, RGI’s geologist performed a site reconnaissance to evaluate the
stability of the site slope. During our field observations, we did not find any signs such as
rotational failures, tension cracks or exposed slope surfaces indicating previous major
Geotechnical Engineering Report 4 April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
landslide activities. No seeps or springs were observed on the slope face through most of
the property. The slope is vegetated with blackberry brambles, vines, ferns, and mixed
brush, with localized small- to medium-diameter deciduous trees scattered throughout
the slope. Based on our observations, the slopes appear to be stable in their current
configuration and condition.
Based on our observations, the existing steep slopes are stable in their present
configuration and condition. The proposed residences will be lightly loaded and
supported by spread footing foundations that transfer the building load to bedrock below
the surface. Based on the subsurface conditions encountered, the proposed development
will not have any impact to the slope stability provided the recommendations in the
report are incorporated into the development plans and followed during construction.
Therefore, RGI recommends the project can be exempted for the setback requirements
for the geologic hazard area.
5.0 Discussion and Recommendations
5.1 GEOTECHNICAL CONSIDERATIONS
Based on our study, the site is suitable for the proposed construction from a geotechnical
standpoint. RGI recommends that proposed buildings be supported on spread footings
bearing on medium dense native soil, bedrock or new structural fill. The slab-on-grade
can be similarly supported on medium dense native soil or structural fill.
Detailed recommendations regarding the above issues and other geotechnical design
considerations are provided in the following sections. These recommendations should be
incorporated into the final design drawings and construction specifications.
5.2 EARTHWORK
RGI expects that site grading will consist of shallow cuts and fills to achieve building and
pavement grades and excavation for utilities including storm, water, sanitary sewer, and
other utilities.
5.2.1 EROSION AND SEDIMENT CONTROL
Potential sources or causes of erosion and sedimentation depend on construction
methods, slope length and gradient, amount of soil exposed and/or disturbed, soil type,
construction sequencing and weather. The impacts on erosion-prone areas can be
reduced by implementing an erosion and sedimentation control plan. The plan should be
designed in accordance with applicable city and/or county standards.
RGI recommends the following erosion control Best Management Practices (BMPs):
Geotechnical Engineering Report 5 April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
Scheduling site preparation and grading for the drier summer and early fall
months and undertaking activities that expose soil during periods of little or no
rainfall
Establishing a quarry spall construction entrance
Installing siltation control fencing or anchored straw or coir wattles on the
downhill side of work areas
Covering soil stockpiles with anchored plastic sheeting
Revegetating or mulching exposed soils with a minimum 3-inch thickness of straw
if surfaces will be left undisturbed for more than one day during wet weather or
one week in dry weather
Directing runoff away from exposed soils and slopes
Minimizing the length and steepness of slopes with exposed soils and cover
excavation surfaces with anchored plastic sheeting (Graded and disturbed slopes
should be tracked in place with the equipment running perpendicular to the slope
contours so that the track marks provide a texture to help resist erosion and
channeling. Some sloughing and raveling of slopes with exposed or disturbed soil
should be expected.)
Decreasing runoff velocities with check dams, straw bales or coir wattles
Confining sediment to the project site
Inspecting and maintaining erosion and sediment control measures frequently
(The contractor should be aware that inspection and maintenance of erosion
control BMPs is critical toward their satisfactory performance. Repair and/or
replacement of dysfunctional erosion control elements should be anticipated.)
Permanent erosion protection should be provided by reestablishing vegetation using
hydroseeding and/or landscape planting. Until the permanent erosion protection is
established, site monitoring should be performed by qualified personnel to evaluate the
effectiveness of the erosion control measures. Provisions for modifications to the erosion
control system based on monitoring observations should be included in the erosion and
sedimentation control plan.
5.2.2 STRIPPING
Stripping efforts should include removal of vegetation, organic materials, and deleterious
debris from areas slated for building, pavement, and utility construction. Topsoil and
rootmass is generally less than 12 inches across the site. Deeper areas of stripping may be
required in heavily vegetated areas of the site.
5.2.3 EXCAVATIONS
All temporary cut slopes associated with the site and utility excavations should be
adequately inclined to prevent sloughing and collapse. The shallow native soil is classified
as Group C soil and bedrock is classified Group A.
Geotechnical Engineering Report 6 April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
Accordingly, for excavations more than 4 feet but less than 20 feet in depth, the
temporary side slopes should be laid back with a minimum slope inclination of 1.5H:1V
(Horizontal:Vertical) in the upper 5 feet and 3/4H:1V in bedrock. If there is insufficient
room to complete the excavations in this manner, or excavations greater than 20 feet in
depth are planned, using temporary shoring to support the excavations should be
considered.
For open cuts at the site, RGI recommends:
No traffic, construction equipment, stockpiles or building supplies are allowed at
the top of cut slopes within a distance of at least 5 feet from the top of the cut
Exposed soil along the slope is protected from surface erosion using waterproof
tarps and/or plastic sheeting
Construction activities are scheduled so that the length of time the temporary cut
is left open is minimized
Surface water is diverted away from the excavation
The general condition of slopes should be observed periodically by a geotechnical
engineer to confirm adequate stability and erosion control measures
In all cases, however, appropriate inclinations will depend on the actual soil and
groundwater conditions encountered during earthwork. Ultimately, the site contractor
must be responsible for maintaining safe excavation slopes that comply with applicable
OSHA or WISHA guidelines.
5.2.4 SITE PREPARATION
RGI anticipates that some areas of loose or soft soil will be exposed upon completion of
stripping and grubbing. Proofrolling and subgrade verification should be considered an
essential step in site preparation. After stripping, grubbing, and prior to placement of
structural fill, RGI recommends proofrolling building and pavement subgrades and areas
to receive structural fill. These areas should be proofrolled under the observation of RGI
and compacted to a firm and unyielding condition in order to achieve a minimum
compaction level of 95 percent of the modified proctor maximum dry density as
determined by the American Society of Testing and Materials D1557-09 Standard Test
Methods for Laboratory Compaction Characteristics of Soil Using Modified Effort (ASTM
D1557).
Proofrolling and adequate subgrade compaction can only be achieved when the soils are
within approximately ± 2 percent moisture content of the optimum moisture content.
Soils that appear firm after stripping and grubbing may be proofrolled with a heavy
compactor, loaded double-axle dump truck, or other heavy equipment under the
observation of an RGI representative. This observer will assess the subgrade conditions
prior to filling. The need for or advisability of proofrolling due to soil moisture conditions
should be determined at the time of construction.
Geotechnical Engineering Report 7 April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
If fill is placed in areas of the site where existing slopes are steeper than 5:1
(Horizontal:Vertical), the area should be benched to reduce the potential for slippage
between existing slopes and fills. Benches should be wide enough to accommodate
compaction and earth moving equipment, and to allow placement of horizontal lifts of fill.
A slope fill detail is shown on Figure 3.
Subgrade soils that become disturbed due to elevated moisture conditions should be
overexcavated to reveal firm, non-yielding, non-organic soils and backfilled with
compacted structural fill. In order to maximize utilization of site soils as structural fill, RGI
recommends that the earthwork portion of this project be completed during extended
periods of warm and dry weather if possible. If earthwork is completed during the wet
season (typically November through May) it will be necessary to take extra precautionary
measures to protect subgrade soils. Wet season earthwork will require additional
mitigative measures beyond that which would be expected during the drier summer and
fall months.
5.2.5 STRUCTURAL FILL
RGI recommends fill below the foundation and floor slab, behind retaining walls, and
below pavement and hardscape surfaces be placed in accordance with the following
recommendations for structural fill.
The suitability of excavated site soils and import soils for compacted structural fill use will
depend on the gradation and moisture content of the soil when it is placed. As the
amount of fines (that portion passing the U.S. No. 200 sieve) increases, soil becomes
increasingly sensitive to small changes in moisture content and adequate compaction
becomes more difficult or impossible to achieve. Soils containing more than about 5
percent fines cannot be consistently compacted to a dense, non-yielding condition when
the moisture content is more than 2 percent above or below optimum. Optimum
moisture content is that moisture that results in the greatest compacted dry density with
a specified compactive effort.
Non-organic site soils are only considered suitable for structural fill provided that their
moisture content is within about 2 percent of the optimum moisture level as determined
by ASTM D1557. Excavated site soils may not be suitable for re-use as structural fill
depending on the moisture content and weather conditions at the time of construction. If
soils are stockpiled for future reuse and wet weather is anticipated, the stockpile should
be protected with plastic sheeting that is securely anchored. Even during dry weather,
moisture conditioning (such as, windrowing and drying) of site soils to be reused as
structural fill may be required. Even during the summer, delays in grading can occur due
to excessively high moisture conditions of the soils or due to precipitation. If wet weather
occurs, the upper wetted portion of the site soils may need to be scarified and allowed to
dry prior to further earthwork, or may need to be wasted from the site.
Geotechnical Engineering Report 8 April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
The native soil contains a large percentage of fines and is moisture sensitive, it may
necessary to import structural fill if the construction occurs in wet season. Import
structural fill should meet the gradation requirements listed in Table 2 for wet weather
conditions. For dry season earthwork, the percent passing the No. 200 may be increased
to 10 percent maximum or materials meeting the 2012 Washington State Department of
Transportation (WSDOT) Standard Specifications for Road, Bridge, and Municipal
Construction, Section 9-03.14(1) may be used.
Table 2 Structural Fill Gradation
U.S. Sieve Size Percent Passing
4 inches 100
No. 4 sieve 75 percent
No. 200 sieve 5 percent *
*Based on minus 3/4 inch fraction.
Prior to use, an RGI representative should observe and test all materials imported to the
site for use as structural fill. Structural fill materials should be placed in uniform loose
layers not exceeding 12 inches and compacted as specified in Table 3. The soil’s maximum
density and optimum moisture should be determined by ASTM D1557.
Table 3 Structural Fill Compaction ASTM D1557
Location Material Type
Minimum
Compaction
Percentage
Moisture Content
Range
Foundations On-site granular or approved
imported fill soils: 95 +2 -2
Retaining Wall Backfill On-site granular or approved
imported fill soils: 92 +2 -2
Slab-on-grade On-site granular or approved
imported fill soils: 95 +2 -2
General Fill (non-
structural areas)
On-site soils or approved
imported fill soils: 90 +3 -2
Pavement – Subgrade
and Base Course
On-site granular or approved
imported fill soils: 95 +2 -2
Placement and compaction of structural fill should be observed by RGI. A representative
number of in-place density tests should be performed as the fill is being placed to confirm
that the recommended level of compaction is achieved.
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Sather Short Plat, Renton, Washington RGI Project No. 2017-035
5.2.6 CUT AND FILL SLOPES
All permanent cut and fill slopes should be graded with a finished inclination no greater
than 2H:1V. Upon completion of construction, the slope face should be trackwalked,
compacted and vegetated, or provided with other physical means to guard against
erosion. All fill placed for slope construction should meet the structural fill requirements
as described in Section 5.2.5.
Final grades at the top of the slopes must promote surface drainage away from the slope
crest. Water must not be allowed to flow in an uncontrolled fashion over the slope face. If
it is necessary to direct surface runoff towards the slope, it should be controlled at the
top of the slope, piped in a closed conduit installed on the slope face, and taken to an
appropriate point of discharge beyond the toe of the slope.
5.2.7 ROCKERIES
Rockeries may be used on the site for grade changes, however, rockeries are not retaining
walls and do require periodic maintenance. RGI can provide supplemental information for
the construction of rockeries once the location and height of the walls has been
determined. Generally, we don’t recommend rockery more than 8 feet in height be used.
A general fill rockery section detail is included on Figure 4. Cut rockeries may also be
feasible and the reinforced section would be replaced with stable native soils. Rockeries
should be constructed by an experienced rockery contractor in accordance with
Associated Rockery Contractors (ARC) guidelines.
5.2.8 WET WEATHER CONSTRUCTION CONSIDERATIONS
RGI recommends that preparation for site grading and construction include procedures
intended to drain ponded water, control surface water runoff, and to collect shallow
subsurface seepage zones in excavations where encountered. It will not be possible to
successfully compact the subgrade or utilize on-site soils as structural fill if accumulated
water is not drained prior to grading or if drainage is not controlled during construction.
Attempting to grade the site without adequate drainage control measures will reduce the
amount of on-site soil effectively available for use, increase the amount of select import
fill materials required, and ultimately increase the cost of the earthwork phases of the
project. Free water should not be allowed to pond on the subgrade soils. RGI anticipates
that the use of berms and shallow drainage ditches, with sumps and pumps in utility
trenches, will be required for surface water control during wet weather and/or wet site
conditions.
5.3 FOUNDATIONS
Following site preparation and grading, the proposed building foundations may be
supported on conventional spread footings bearing on medium dense native soil, bedrock
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Sather Short Plat, Renton, Washington RGI Project No. 2017-035
or new structural fill. Where loose soils or other unsuitable soils are encountered in the
proposed building footprint, they should be overexcavated and backfilled with structural
fill.
Perimeter foundations exposed to weather should be at a minimum depth of 18 inches
below final exterior grades. Interior foundations can be constructed at any convenient
depth below the floor slab. Finished grade is defined as the lowest adjacent grade within
5 feet of the foundation for perimeter (or exterior) footings and finished floor level for
interior footings.
Table 4 Foundation Design
Design Parameter Value
Allowable Bearing Capacity 2,500 psf1
Friction Coefficient 0.25
Passive pressure (equivalent fluid pressure) 250 pcf2
Minimum foundation dimensions Columns: 24 inches
Walls: 16 inches
1 psf = pounds per square foot
2 pcf = pounds per cubic foot
The allowable foundation bearing pressures apply to dead loads plus design live load
conditions. For short-term loads, such as wind and seismic, a 1/3 increase in this
allowable capacity may be used. At perimeter locations, RGI recommends not including
the upper 12 inches of soil in the computation of passive pressures because it can be
affected by weather or disturbed by future grading activity. The passive pressure value
assumes the foundation will be constructed neat against competent soil or backfilled with
structural fill as described in Section 5.2.5. The recommended base friction and passive
resistance value includes a safety factor of about 1.5.
With spread-footing foundations designed in accordance with the recommendations in
this section, maximum total and differential post-construction settlements of 1 inch and
1/2 inch, respectively, should be expected.
5.4 RETAINING WALLS
RGI recommends cast-in-place concrete walls be used for basement wall (if needed). The
magnitude of earth pressure development on retaining walls will partly depend on the
quality of the wall backfill. RGI recommends placing and compacting wall backfill as
structural fill. Wall drainage will be needed behind the wall face. A typical retaining wall
drainage detail is shown on Figure 5. With wall backfill placed and compacted as
recommended, and drainage properly installed, RGI recommends using the values in the
following table for design.
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Sather Short Plat, Renton, Washington RGI Project No. 2017-035
Table 5 Retaining Wall Design
Design Parameter Value
Allowable Bearing Capacity 2,500 psf
Active Earth Pressure (unrestrained walls) 35 pcf
At-rest Earth Pressure (restrained walls) 50 pcf
For seismic design, an additional uniform load of 7 times the wall height (H) for
unrestrained walls and 14H for restrained walls should be applied to the wall surface.
Friction at the base of foundations and passive earth pressure will provide resistance to
these lateral loads. Values for these parameters are provided in Section 5.3.
5.5 SLAB-ON-GRADE CONSTRUCTION
Once site preparation has been completed as described in Section 5.2, suitable support
for slab-on-grade construction should be provided. Immediately below the floor slab, RGI
recommends placing a 4-inch-thick capillary break layer of clean, free-draining pea gravel,
washed rock, or crushed rock that has less than 5 percent passing the U.S. No. 200 sieve.
This material will reduce the potential for upward capillary movement of water through
the underlying soil and subsequent wetting of the floor slab.
Where moisture by vapor transmission is undesirable, an 8- to 10-millimeter-thick plastic
membrane should be placed on a 4-inch-thick layer of clean gravel or rock. For the
anticipated floor slab loading, we estimate post-construction floor settlements of ¼- to ½-
inch.
5.6 DRAINAGE
5.6.1 SURFACE
Final exterior grades should promote free and positive drainage away from the building
area. Water must not be allowed to pond or collect adjacent to foundations or within the
immediate building area. For non-pavement locations, RGI recommends providing a
minimum drainage gradient of 3 percent for a minimum distance of 10 feet from the
building perimeter. In paved locations, a minimum gradient of 1 percent should be
provided unless provisions are included for collection and disposal of surface water
adjacent to the structure.
5.6.2 SUBSURFACE
RGI recommends installing perimeter foundation drain as shown on Figure 6. The
retaining wall drains, perimeter foundation drain, and roof downspouts should be
tightlined separately to an approved discharge facility. Subsurface drains must be laid
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Sather Short Plat, Renton, Washington RGI Project No. 2017-035
with a gradient sufficient to promote positive flow to a controlled point of approved
discharge.
5.6.3 INFILTRATION
At the time of performing this study, RGI understands that infiltration systems are being
considered for the on-site disposal of storm water run-off by the design team. Based on
the soil encountered, the native soil or bedrock is not suitable for infiltration.
5.7 UTILITIES
Utility pipes should be bedded and backfilled in accordance with American Public Works
Association (APWA) specifications. For site utilities located within the right-of-ways,
bedding and backfill should be completed in accordance with City of Renton
specifications. At a minimum, trench backfill should be placed and compacted as
structural fill, as described in Section 5.2.5. Where utilities occur below unimproved
areas, the degree of compaction can be reduced to a minimum of 90 percent of the soil’s
maximum density as determined by ASTM D1557. The native soil is not suitable for
structural fill. Imported structural fill will be necessary for trench backfill as
recommended in Section 5.2.5.
5.8 PAVEMENTS
RGI recommends that the driveway to the new garage be stripped and repaved.
Pavement subgrades should be prepared as described in Section 5.2 of this GER and as
discussed below. Regardless of the relative compaction achieved, the subgrade must be
firm and relatively unyielding before paving. This condition should be verified by
proofrolling with heavy construction equipment or hand probe by inspector.
With the pavement subgrade prepared as described above, RGI recommends the
following pavement section with flexible asphalt concrete surfacing.
For private asphalt driveways: 2 inches of hot mix asphalt over 6 inches of
crushed rock base (CRB) over compacted subgrade;
The asphalt paving materials used should conform to the Washington State Department
of Transportation (WSDOT) specifications for Hot Mix Asphalt Class 1/2 inch and CRB
surfacing.
If concrete driveway is preferred, the following section can be used.
For concrete driveways: 5 inches of concrete over 4 inches of CRB over
compacted subgrade
Long-term pavement performance will depend on surface drainage. A poorly-drained
pavement section will be subject to premature failure as a result of surface water
infiltrating into the subgrade soils and reducing their supporting capability.
Geotechnical Engineering Report 13 April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
For optimum pavement performance, surface drainage gradients of no less than 2
percent are recommended. Also, some degree of longitudinal and transverse cracking of
the pavement surface should be expected over time. Regular maintenance should be
planned to seal cracks when they occur.
5.9 CONSTRUCTION CONSIDERATIONS
An important construction consideration is the weather and its impact on construction
scheduling. Although it is not impossible, winter construction will be more difficult and
will increase construction costs. RGI highly recommends that the major earthwork be
performed in dry season from May to September.
Rock blasting may be needed during foundation excavation extending into bedrock.
Detailed design of excavation operation is usually the responsibility of the earthwork
contractor, while the principal duty of the owner’s representative is to ensure that the
designed results are being produced.
We recommend that an experienced geotechnical engineer or geologist be present on-
site to observe site grading, excavation cut slopes, structural fill placement, and the
foundation subgrade preparation.
6.0 Additional Services
RGI is available to provide further geotechnical consultation throughout the design phase
of the project. RGI should review the grading and utilities plans in order to verify that
earthwork and foundation recommendations in this report are appropriate and provide
supplemental recommendations as necessary.
RGI should be contracted to provide geotechnical engineering and construction
monitoring services during. The integrity of the earthwork and construction depends on
proper site preparation and procedures. In addition, engineering decisions may arise in
the field in the event that variations in subsurface conditions become apparent.
Construction monitoring services are not part of this scope of work. RGI can provide an
estimate for these services once the construction plans and schedule have been
developed.
7.0 Limitations
This GER is the property of RGI, Ms. Sather and her designated agents. Within the limits of
the scope and budget, this GER was prepared in accordance with generally accepted
geotechnical engineering practices in the area at the time this report was issued. This GER
is intended for specific application to the Sather Short Plat at 532 Southwest 3rd Place in
Renton, Washington, and for the exclusive use of Ms. Sather and her authorized
Geotechnical Engineering Report 14 April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
representatives. No other warranty, expressed or implied, is made. Site safety, excavation
support, and dewatering requirements are the responsibility of others.
The scope of services for this project does not include either specifically or by implication
any environmental or biological (for example, mold, fungi, bacteria) assessment of the
site or identification or prevention of pollutants, hazardous materials, or conditions. If the
owner is concerned about the potential for such contamination or pollution, we can
provide a proposal for these services.
The analyses and recommendations presented in this GER are based upon review of the
previous explorations on the site by Geotechnical Investigations Group. Variations in soil
conditions can occur, the nature and extent of which may not become evident until
construction. If variations appear evident, RGI should be requested to reevaluate the
recommendations in this GER prior to proceeding with construction.
It is client’s responsibility to see that all parties to the project, including the designers,
contractors, subcontractors, are made aware of this GER in its entirety. The use of
information contained in this GER for bidding purposes should be done at the contractor’s
option and risk.
USGS, 2014, Renton, Washington
7.5-Minute Quadrangle
Approximate Scale: 1"=1000'
0 500 1000 2000 N
Site Vicinity Map
Figure 1
04/2017
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone: 425.415.0551
Fax: 425.415.0311
Sather Short Plat
RGI Project Number
2017-035
Date Drawn:
Address: 532 Southwest 3rd Place, Renton, Washington 98057
SITE
TP-4
TP-3
TP-1
TP-2
N
Geotechnical Exploration Plan
Figure 2
Approximate Scale: 1"=40'
0 20 40 80
= Test pit excavated by RGI, 3/22/17
= Site boundary
04/2017
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone: 425.415.0551
Fax: 425.415.0311
Sather Short Plat
RGI Project Number
2017-035
Date Drawn:
Address: 532 Southwest 3rd Place, Renton, Washington 98057
04/2017
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone: 425.415.0551
Fax: 425.415.0311
Sather Short Plat
RGI Project Number
2017-035
Date Drawn:
Address: 532 Southwest 3rd Place, Renton, Washington 98057
General Slope Fill Detail
Figure 3
Not to Scale
Slope should be stripped of topsoil and unsuitable soils prior to placing any fill.
in 1 cu.ft. 3/4" Drainage Gravel
4" Diameter Perforated Pipe Enveloped
Key Cute and Toe Drain -
ASTM D-698 (standard proctor).
All structural fill should be compacted to 95% of soils maximum dry density per
Plant or hydroseed slope face to reduce erosion potential.
Final slope face should be densified by compaction.
"Key" should be minimum 2 feet deep and 6 feet wide, extending the full length of
"Benches" should be a minimum of 6 feet wide.
1.
the slope face.
4.
6.
5.
3.
2.
Notes
New Structural Fill
Maximum Slope Gradient: 2:1(H:V)
Grade
Existing
Topsoil and Other Loose Soils
Grade After the Removal of
Conditions are Indicated
May Require Subdrain if Seepage
Typical Bench -
1
2
Slope to Drain
Keyway
down towards the face
Keyway should be sloped
being protected
18 in. min.
by Geotechnical Engineer
soil to be verified
Firm undisturbed
H/3
gravel
clean washed 3/4" drain
drain pipe surrounded by
4 in. minimum diameter
12 in.
min.
3 in. min. gravel bedding
Swale for surface drainage control
1
6
Crushed rock filter
material, between 2
and 4 inch size with
L
1.5'
1.5'
1.5'
Slope 2:1(H:V) max.
1
2
1.5'
less than 2% fines.
0.5' (typ.)
3' (min.)
NOT TO SCALE
H = 8'
Reinforcement (Mirafi 7XT)
L > 2/3 of rockery height
0.5'
04/2017
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone: 425.415.0551
Fax: 425.415.0311
Sather Short Plat
RGI Project Number
2017-035
Date Drawn:
Address: 532 Southwest 3rd Place, Renton, Washington 98057
Typical Rockery Section Detail
Figure 4
Incliniations)
12" Over the Pipe
3" Below the Pipe
Perforated Pipe
4" Diameter PVC
Compacted Structural
Backfill (Native or Import)
12" min.
Filter Fabric Material
12" Minimum Wide
Free-Draining Gravel
Slope to Drain
(See Report for
Appropriate
Excavated Slope
04/2017
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone: 425.415.0551
Fax: 425.415.0311
Sather Short Plat
RGI Project Number
2017-035
Date Drawn:
Address: 532 Southwest 3rd Place, Renton, Washington 98057
Retaining Wall Drainage Detail
Figure 5
Not to Scale
3/4" Washed Rock or Pea Gravel
4" Perforated Pipe
Building Slab
Structural
Backfill
Compacted
Filter Fabric
04/2017
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone: 425.415.0551
Fax: 425.415.0311
Sather Short Plat
RGI Project Number
2017-035
Date Drawn:
Address: 532 Southwest 3rd Place, Renton, Washington 98057
Typical Footing Drain Detail
Figure 6
Not to Scale
Geotechnical Engineering Report April 7, 2017
Sather Short Plat, Renton, Washington RGI Project No. 2017-035
APPENDIX A
FIELD EXPLORATION AND LABORATORY TESTING
On March 22, 2017, RGI performed field explorations using an excavator. RGI explored
subsurface soil conditions at the site by observing the excavation of four test pits to a
maximum depth of 6 feet below existing grade. The test pit locations are shown on Figure
2. The test pit locations were approximately determined by measurements from existing
site features and topography.
A geologist from our office conducted the field exploration and classified the soil
conditions encountered, maintained a log of each test exploration, obtained
representative soil samples, and observed pertinent site features. All soil samples were
visually classified in accordance with the Unified Soil Classification System (USCS).
Representative soil samples obtained from the explorations were placed in closed
containers and taken to our laboratory for further examination and testing. As a part of
the laboratory testing program, the soil samples were classified in our in-house laboratory
based on visual observation, texture, plasticity, and the limited laboratory testing
described below.
Moisture Content Determinations
Moisture content determinations were performed in accordance with ASTM D2216-10
Standard Test Methods for Laboratory Determination of Water (Moisture) Content of Soil
and Rock by Mass (ASTM D2216) on representative samples obtained from the
exploration in order to aid in identification and correlation of soil types. The moisture
content of typical samples were measured and is reported on the test pit logs.
Grain Size Analysis
A grain size analysis indicates the range in diameter of soil particles included in a
particular sample. Grain size analyses was determined using D6913-04(2009) Standard
Test Methods for Particle-Size Distribution (Gradation) of Soils Using Sieve Analysis (ASTM
D6913) on two of the samples.
Project Name:Sather Short Plat
Project Number:2017-035
Client:Patty Sather
Test Pit No.: TP-1
Date(s) Excavated:3/22/2017
Excavation Method:Trackhoe
Excavator Type:Tracked Excavator
Groundwater Level:Seepage at 3' and 5'
Test Pit Backfill:Cuttings
Logged By ELW
Bucket Size:N/A
Excavating Contractor:Kelly's Excavating
Sampling
Method(s)Grab
Location 532 Southwest 3rd Place, Renton, Washington
Surface Conditions:Mixed Brush
Total Depth of Excavation:6 feet bgs
Approximate
Surface Elevation 178
Compaction Method Bucket
USCS SymbolTopsoil
SM
Sandstone
REMARKS AND OTHER TESTS
23% moisture, 33% fines
14% moistureGraphic LogMATERIAL DESCRIPTION
8" topsoil
Tan to brown mottled silty SAND, loose, moist to wet
Becomes medium dense, wet
Light groundwater seepage at 3'
Becomes medium dense to dense, light seepage at 5'
Tan SANDSTONE, very dense, moist
Test Pit terminated at 6' due to refusal in bedrockDepth (feet)0
5
10 Sample NumberSample TypeElevation (feet)178
173
168
Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Sather Short Plat
Project Number:2017-035
Client:Patty Sather
Test Pit No.: TP-2
Date(s) Excavated:3/22/2017
Excavation Method:Trackhoe
Excavator Type:Tracked Excavator
Groundwater Level:Not encountered
Test Pit Backfill:Cuttings
Logged By ELW
Bucket Size:N/A
Excavating Contractor:Kelly's Excavating
Sampling
Method(s)Grab
Location 532 Southwest 3rd Place, Renton, Washington
Surface Conditions:Mixed Brush
Total Depth of Excavation:6 feet bgs
Approximate
Surface Elevation 190
Compaction Method Bucket
USCS SymbolTopsoil
Fill
SM
Sandstone
REMARKS AND OTHER TESTS
17% moisture
18% moisture
14% moistureGraphic LogMATERIAL DESCRIPTION
12" topsoil
Light brown silty SAND, loose, moist to wet (Fill)
Tan mottled silty SAND, medium dense, ,moist
Tan SANDSTONE, very dense, moist
Iron oxide staining
Test Pit terminated at 6' due to refusal in bedrockDepth (feet)0
5
10 Sample NumberSample TypeElevation (feet)190
185
180
Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Sather Short Plat
Project Number:2017-035
Client:Patty Sather
Test Pit No.: TP-3
Date(s) Excavated:3/22/2017
Excavation Method:Trackhoe
Excavator Type:Tracked Excavator
Groundwater Level:Not encountered
Test Pit Backfill:Cuttings
Logged By ELW
Bucket Size:N/A
Excavating Contractor:Kelly's Excavating
Sampling
Method(s)Grab
Location 532 Southwest 3rd Place, Renton, Washington
Surface Conditions:Mixed Brush
Total Depth of Excavation:5.5 feet bgs
Approximate
Surface Elevation 190
Compaction Method Bucket
USCS SymbolTopsoil
Fill
SM
Sandstone
REMARKS AND OTHER TESTS
21% moisture
23% moisture, 21% fines
13% moistureGraphic LogMATERIAL DESCRIPTION
10" topsoil
Brown silty SAND, loose, moist to wet (Fill)
Trace organics
Tan mottled silty SAND, medium dense, moist to wet
Tan SANDSTONE, very dense, moist
Test Pit terminated at 5.5' due to refusal in bedrockDepth (feet)0
5
10 Sample NumberSample TypeElevation (feet)190
185
180
Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Sather Short Plat
Project Number:2017-035
Client:Patty Sather
Test Pit No.: TP-4
Date(s) Excavated:3/22/2017
Excavation Method:Trackhoe
Excavator Type:Tracked Excavator
Groundwater Level:Not encountered
Test Pit Backfill:Cuttings
Logged By ELW
Bucket Size:N/A
Excavating Contractor:Kelly's Excavating
Sampling
Method(s)Grab
Location 532 Southwest 3rd Place, Renton, Washington
Surface Conditions:Mixed Brush
Total Depth of Excavation:4.5 feet bgs
Approximate
Surface Elevation 198
Compaction Method Bucket
USCS SymbolTopsoil
SM
Sandstone
REMARKS AND OTHER TESTS
18% moisture
14% moistureGraphic LogMATERIAL DESCRIPTION
12" topsoil
Tan mottled silty SAND, loose, moist to wet
Becomes medium dense
Tan SANDSTONE, very dense, moist
Oron oxide staining
Test Pit terminated at 4.5' due to refusal in bedrockDepth (feet)0
5
10 Sample NumberSample TypeElevation (feet)198
193
188
Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Sather Short Plat
Project Number:2017-035
Client:Patty Sather
Key to Logs
USCS SymbolREMARKS AND OTHER TESTSGraphic LogMATERIAL DESCRIPTIONDepth (feet)Sample NumberSample TypeElevation (feet)1 2 3 4 5 6 7 8
COLUMN DESCRIPTIONS
1 Elevation (feet): Elevation (MSL, feet).
2 Depth (feet): Depth in feet below the ground surface.
3 Sample Type: Type of soil sample collected at the depth interval
shown.
4 Sample Number: Sample identification number.
5 USCS Symbol: USCS symbol of the subsurface material.
6 Graphic Log: Graphic depiction of the subsurface material
encountered.
7 MATERIAL DESCRIPTION: Description of material encountered.
May include consistency, moisture, color, and other descriptive
text.
8 REMARKS AND OTHER TESTS: Comments and observations
regarding drilling or sampling made by driller or field personnel.
FIELD AND LABORATORY TEST ABBREVIATIONS
CHEM: Chemical tests to assess corrosivity
COMP: Compaction test
CONS: One-dimensional consolidation test
LL: Liquid Limit, percent
PI: Plasticity Index, percent
SA: Sieve analysis (percent passing No. 200 Sieve)
UC: Unconfined compressive strength test, Qu, in ksf
WA: Wash sieve (percent passing No. 200 Sieve)
MATERIAL GRAPHIC SYMBOLS
AF
Sandstone
Silty SAND (SM)
TYPICAL SAMPLER GRAPHIC SYMBOLS
Auger sampler
Bulk Sample
3-inch-OD California w/
brass rings
CME Sampler
Grab Sample
2.5-inch-OD Modified
California w/ brass liners
Pitcher Sample
2-inch-OD unlined split
spoon (SPT)
Shelby Tube (Thin-walled,
fixed head)
OTHER GRAPHIC SYMBOLS
Water level (at time of drilling, ATD)
Water level (after waiting)
Minor change in material properties within a
stratum
Inferred/gradational contact between strata
?Queried contact between strata
GENERAL NOTES
1: Soil classifications are based on the Unified Soil Classification System. Descriptions and stratum lines are interpretive, and actual lithologic changes may be
gradual. Field descriptions may have been modified to reflect results of lab tests.
2: Descriptions on these logs apply only at the specific boring locations and at the time the borings were advanced. They are not warranted to be representative
of subsurface conditions at other locations or times.
Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
THE RILEY GROUP, INC.
17522 Bothell Way NE
Bothell, WA 98011
PHONE: (425) 415-0551
FAX: (425) 415-0311
GRAIN SIZE ANALYSIS
ASTM D421, D422, D1140, D2487, D6913
PROJECT TITLE Sather Short Plat SAMPLE ID/TYPE TP-1
PROJECT NO.2017-035 SAMPLE DEPTH 2'
TECH/TEST DATE ELW 3/22/2017 DATE RECEIVED 3/22/2017
WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture
Wt Wet Soil & Tare (gm) (w1)255.6 Weight Of Sample (gm)211.0
Wt Dry Soil & Tare (gm)(w2)211.0 Tare Weight (gm) 15.7
Weight of Tare (gm)(w3)15.7 (W6) Total Dry Weight (gm)195.3
Weight of Water (gm)(w4=w1-w2)44.6 SIEVE ANALYSIS
Weight of Dry Soil (gm) (w5=w2-w3)195.3 Cumulative
Moisture Content (%) (w4/w5)*100 23 Wt Ret (Wt-Tare) (%Retained)% PASS
+Tare {(wt ret/w6)*100}(100-%ret)
% COBBLES 0.0 12.0"15.7 0.00 0.00 100.00 cobbles
% C GRAVEL 0.0 3.0"15.7 0.00 0.00 100.00 coarse gravel
% F GRAVEL 0.8 2.5" coarse gravel
% C SAND 2.3 2.0" coarse gravel
% M SAND 6.7 1.5"15.7 0.00 0.00 100.00 coarse gravel
% F SAND 57.8 1.0" coarse gravel
% FINES 32.5 0.75"15.7 0.00 0.00 100.00 fine gravel
% TOTAL 100.0 0.50" fine gravel
0.375"15.7 0.00 0.00 100.00 fine gravel
D10 (mm)#4 17.2 1.50 0.77 99.23 coarse sand
D30 (mm)#10 21.6 5.90 3.02 96.98 medium sand
D60 (mm)#20 medium sand
Cu #40 34.7 19.00 9.73 90.27 fine sand
Cc #60 fine sand
#100 124.6 108.90 55.76 44.24 fine sand
#200 147.6 131.90 67.54 32.46 fines
PAN 211.0 silt/clay
DESCRIPTION Silty SAND
USCS SM
Prepared For: Patty Sather Reviewed By:RW
0
10
20
30
40
50
60
70
80
90
100
0.0010.010.11101001000
%
P
A
S
S
I
N
G
Grain size in millimeters
12"3"2"1".75".375"#4 #10 #20 #40 #60 #100 #200
THE RILEY GROUP, INC.
17522 Bothell Way NE
Bothell, WA 98011
PHONE: (425) 415-0551
FAX: (425) 415-0311
GRAIN SIZE ANALYSIS
ASTM D421, D422, D1140, D2487, D6913
PROJECT TITLE Sather Short Plat SAMPLE ID/TYPE TP-3
PROJECT NO.2017-035 SAMPLE DEPTH 4'
TECH/TEST DATE ELW 3/22/2017 DATE RECEIVED 3/22/2017
WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture
Wt Wet Soil & Tare (gm) (w1)289.7 Weight Of Sample (gm)238.9
Wt Dry Soil & Tare (gm)(w2)238.9 Tare Weight (gm) 15.7
Weight of Tare (gm)(w3)15.7 (W6) Total Dry Weight (gm)223.2
Weight of Water (gm)(w4=w1-w2)50.8 SIEVE ANALYSIS
Weight of Dry Soil (gm) (w5=w2-w3)223.2 Cumulative
Moisture Content (%) (w4/w5)*100 23 Wt Ret (Wt-Tare) (%Retained)% PASS
+Tare {(wt ret/w6)*100}(100-%ret)
% COBBLES 0.0 12.0"15.7 0.00 0.00 100.00 cobbles
% C GRAVEL 0.0 3.0"15.7 0.00 0.00 100.00 coarse gravel
% F GRAVEL 0.4 2.5" coarse gravel
% C SAND 4.8 2.0" coarse gravel
% M SAND 14.8 1.5"15.7 0.00 0.00 100.00 coarse gravel
% F SAND 59.4 1.0" coarse gravel
% FINES 20.5 0.75"15.7 0.00 0.00 100.00 fine gravel
% TOTAL 100.0 0.50" fine gravel
0.375"15.7 0.00 0.00 100.00 fine gravel
D10 (mm)#4 16.6 0.90 0.40 99.60 coarse sand
D30 (mm)#10 27.4 11.70 5.24 94.76 medium sand
D60 (mm)#20 medium sand
Cu #40 60.5 44.80 20.07 79.93 fine sand
Cc #60 fine sand
#100 167.8 152.10 68.15 31.85 fine sand
#200 193.1 177.40 79.48 20.52 fines
PAN 238.9 silt/clay
DESCRIPTION Silty SAND
USCS SM
Prepared For: Patty Sather Reviewed By:RW
0
10
20
30
40
50
60
70
80
90
100
0.0010.010.11101001000
%
P
A
S
S
I
N
G
Grain size in millimeters
12"3"2"1".75".375"#4 #10 #20 #40 #60 #100 #200