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GEOTECHNICAL ENGINEERING REPORT
PREPARED BY:
THE RILEY GROUP, INC.
17522 BOTHELL WAY NORTHEAST
BOTHELL, WASHINGTON 98011
PREPARED FOR:
MS. KELLY BEYMER
ADMINISTRATOR OF COMMUNITY SERVICE DEPARTMENT
CITY OF RENTON
1055 SOUTH GRADY WAY
RENTON, WASHINGTON 98057
RGI PROJECT NO. 2018-130
FAMILY FIRST COMMUNITY CENTER
16022 116TH AVENUE SOUTHEAST
RENTON, WASHINGTON 98058
JUNE 8, 2018
Geotechnical Engineering Report June 8, 2018
Family First Community Center, Renton, Washington RGI Project No. 2018-130
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 COAL MINE HAZARD .................................................................................................................................. 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 ................................................................................................................................ 6
5.2.6 Cut and Fill Slopes ........................................................................................................................ 8
5.2.7 Wet Weather Construction Considerations ................................................................................. 8
5.3 FOUNDATIONS .......................................................................................................................................... 9
5.4 RETAINING WALLS ................................................................................................................................... 10
5.5 SLAB-ON-GRADE CONSTRUCTION ............................................................................................................... 10
5.6 DRAINAGE .............................................................................................................................................. 10
5.6.1 Surface ....................................................................................................................................... 10
5.6.2 Subsurface .................................................................................................................................. 11
5.6.3 Infiltration .................................................................................................................................. 11
5.7 UTILITIES ................................................................................................................................................ 11
5.8 PAVEMENTS ............................................................................................................................................ 11
5.9 CONSTRUCTION CONSIDERATIONS ............................................................................................................... 12
6.0 ADDITIONAL SERVICES .................................................................................................................. 12
7.0 LIMITATIONS ................................................................................................................................. 12
LIST OF APPENDICES
Figure 1 ..................................................................................................................... Site Vicinity Map
Figure 2 ............................................................................................... Geotechnical Exploration Plan
Figure 3 ............................................................................................... Retaining Wall Drainage Detail
Figure 4 ....................................................................................................Typical Footing Drain Detail
Appendix A .......................................................................... Field Exploration and Laboratory Testing
Geotechnical Engineering Report June 8, 2018
Family First Community Center, Renton, Washington RGI Project No. 2018-130
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 seven test borings to a
maximum depth of 16.5 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 up to 11 feet of fill comprised of loose to medium
dense silty sand with varying amounts of gravel over medium dense to very dense silty
sand with varying amounts of gravel, and localized silty sand, sandy gravel, and sand with
some silt and gravel.
Groundwater: Groundwater seepage was encountered at 15 feet bgs in two of the test
borings during our subsurface exploration.
Foundations: The proposed buildings can be supported on spread footing foundation
bearing on competent native soil 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.
Geotechnical Engineering Report 1 June 8, 2018
Family First Community Center, Renton, Washington RGI Project No. 2018-130
1.0 Introduction
This Geotechnical Engineering Report (GER) presents the results of the geotechnical
engineering services provided for the Family First Community Center in Renton,
Washington. The purpose of this GER is to assess subsurface conditions and provide
geotechnical recommendations for building a one-story community center building. 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 16022 116th Avenue Southeast in Renton, Washington. The
approximate location of the site is shown on Figure 1.
The site includes a rectangular shaped parcel of land about 14.9 aces in size. The northern
portion of the site is occupied by a school building and facilities. The proposed
development will be located at the southwest corner of the property.
The proposed Family First Community Center building will be a one-story building about
30,000 square feet in size with a slab on grade floor. Our understanding of the project is
based on the Master Site Plan prepared by Baylis Architecture dated February 26, 2018.
RGI expects the proposed building will be a one-story, light-weight structure with a
maximum column load of less than 100 kips. Slab-on-grade floor loading of 150 pounds
per square foot (psf) are expected. RGI anticipates that grading with fill up to
approximately 10 feet will be needed in the existing stormwater pond area to reach the
design grade.
3.0 Field Exploration and Laboratory Testing
On May 23, 2018, RGI performed subsurface exploration using a tracked drill rig. A total
of seven test borings were advanced 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 borings.
These logs included visual classifications of the materials encountered during excavation
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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.
4.0 Site Conditions
4.1 SURFACE
The entire site includes a rectangular shaped parcel of land about 14.9 aces in size. The
proposed development area is located in the southwest portion of the site and is
approximately 3.35 acres in size. The project area is bound to the north and east by the
existing school building and facilities, to the south by residential properties, and to the
west by 116th Avenue Southeast.
The western portion of the proposed development area is a paved parking lot. An existing
storm water pond approximately 10 feet deep is located along the southern property line.
To the north of the pond, there is 5-foot hump area that appears to have been created by
the excavated soil from the pond excavation.
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 till (Map Unit Qvt) which is compact diamict
containing subrounded to well-rounded clasts, glacially transported and deposited.
Generally forms undulating layers a few meters to a few tens of meters thick. The native
soil below the fill encountered during field exploration appears to match the description.
4.3 SOILS
The site is underlain by up to 11 feet of fill comprised of loose to medium dense silty sand
with varying amounts of gravel over medium dense to very dense silty sand with varying
amounts of gravel, and localized silty sand, sandy gravel, and sand with some silt and
gravel. More detailed descriptions of the subsurface conditions encountered are
presented in the test borings included in Appendix A.
4.4 GROUNDWATER
Groundwater seepage was encountered at 15 feet bgs in two of the test borings during
our subsurface exploration.
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,
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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.
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 D2
Site Latitude 47.45859 N
Site Longitude 122.18416 W
Maximum considered earthquake spectral response acceleration
parameters (g) Ss = 1.399, S1 = 0.522
Spectral response acceleration parameters adjusted for site class
(g) Sms = 1.399, Sm1 = 0.783
Design spectral response acceleration parameters (g) Sds = 0.933, Sd1 = 0.522
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 16.5 feet, and this seismic site class definition considers that similar 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. The site is underlain by till
which is considered not liquefiable.
4.6 COAL MINE HAZARD
RGI has reviewed the City of Renton Coal Mine Hazards map dated November 12, 2014.
The project site is not mapped as a coal mine hazard area.
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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 or 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 cut in the high area of the site and fill in the
pond area 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):
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
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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. The existing pond should be dry before
filling and the wet soil and vegetation should be removed before filling.
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 native dense soil is classified Group A.
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 dense native soil. 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
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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
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.
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
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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 the 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.
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.
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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.
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 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
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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 or
structural fill. The existing fill may be suitable for support of foundations and should be
evaluated during construction. 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.
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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 3. With wall backfill placed and compacted as
recommended, and drainage properly installed, RGI recommends using the values in the
following table for design.
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
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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 4. The
retaining wall drains, perimeter foundation drain, and roof downspouts should be
tightlined separately to an approved discharge facility. Subsurface drains must be laid
with a gradient sufficient to promote positive flow to a controlled point of approved
discharge.
5.6.3 INFILTRATION
Based on the soil encountered, the native soil 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. If the native soil becomes unsuitable
for use as 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 or parking: 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.
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Family First Community Center, Renton, Washington RGI Project No. 2018-130
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.
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.
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, City of Renton 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 Family First Community Center
at 16022 116th Avenue Southeast in Renton, Washington, and for the exclusive use of the
City of Renton and its authorized representatives. No other warranty, expressed or
Geotechnical Engineering Report 13 June 8, 2018
Family First Community Center, Renton, Washington RGI Project No. 2018-130
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
06/2018
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone: 425.415.0551
Fax: 425.415.0311
Family First Community Center
RGI Project Number
2018-130
Date Drawn:
Address: 16022 116th Avenue Southeast, Renton, Washington 98058
SITE
B-1B-2B-3B-4B-5B-6B-706/2018Corporate Office17522 Bothell Way NortheastBothell, Washington 98011Phone: 425.415.0551Fax: 425.415.0311Family First Community CenterRGI Project Number2018-130Date Drawn:Address: 16022 116th Avenue Southeast, Renton, Washington 98058Geotechnical Exploration PlanFigure 2Approximate Scale: 1"=120'060120240N= Boring by RGI, 5/23/18= Site boundary
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
06/2018
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone: 425.415.0551
Fax: 425.415.0311
Family First Community Center
RGI Project Number
2018-130
Date Drawn:
Address: 16022 116th Avenue Southeast, Renton, Washington 98058
Retaining Wall Drainage Detail
Figure 3
Not to Scale
3/4" Washed Rock or Pea Gravel
4" Perforated Pipe
Building Slab
Structural
Backfill
Compacted
Filter Fabric
06/2018
Corporate Office
17522 Bothell Way Northeast
Bothell, Washington 98011
Phone: 425.415.0551
Fax: 425.415.0311
Family First Community Center
RGI Project Number
2018-130
Date Drawn:
Address: 16022 116th Avenue Southeast, Renton, Washington 98058
Typical Footing Drain Detail
Figure 4
Not to Scale
Geotechnical Engineering Report June 8, 2018
Family First Community Center, Renton, Washington RGI Project No. 2018-130
APPENDIX A
FIELD EXPLORATION AND LABORATORY TESTING
On May 23, 2018, RGI performed field explorations using a tracked drill rig. RGI explored
subsurface soil conditions at the site by observing the drilling of 7 test borings to a
maximum depth of 16.5 feet below existing grade. The boring locations are shown on
Figure 2. The boring 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 four of the samples.
Project Name:Family First Community Center
Project Number:2018-130
Client:City of Renton
Boring No.:B-1
Date(s) Drilled:5/23/2018
Drilling Method(s):Hollow Stem Auger
Drill Rig Type:Track Rig
Groundwater Level:Seepage at 15'
Borehole Backfill:Bentonite Chips
Logged By:ELW
Drill Bit Size/Type:8" auger
Drilling Contractor:Bortec
Sampling Method(s):SPT
Location:16022 116th Avenue Southeast, Renton, Washington
Surface Conditions:Asphalt
Total Depth of Borehole:16.5 feet bgs
Approximate
Surface Elevation:N/A
Hammer Data :140 lb, 30" drop, rope and
cathead
USCS SymbolAsphalt
Fill
SM
GP
SM Moisture (%)12
17
20
11
17
13Recovery (%)Graphic LogRQD (%)MATERIAL DESCRIPTION
6" asphalt over crushed rock base
Gray silty SAND with some gravel, medium dense, moist (Fill)
Little recovery
Becomes brown to gray, moist to wet, trace organics
Brown silty SAND with some gravel, medium dense, wet
22% fines
Brown sandy GRAVEL, very dense, saturated
Tan silty SAND, very dense, moist
Boring terminated at 16' 6"Depth (feet)0
5
10
15 Sample TypeSampling Resistance, blows/ft21
14
13
74Elevation (feet)Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Family First Community Center
Project Number:2018-130
Client:City of Renton
Boring No.:B-2
Date(s) Drilled:5/23/2018
Drilling Method(s):Hollow Stem Auger
Drill Rig Type:Track Rig
Groundwater Level:Not Encountered
Borehole Backfill:Bentonite Chips
Logged By:ELW
Drill Bit Size/Type:8" auger
Drilling Contractor:Bortec
Sampling Method(s):SPT
Location:16022 116th Avenue Southeast, Renton, Washington
Surface Conditions:Grass
Total Depth of Borehole:16.33 feet bgs
Approximate
Surface Elevation:N/A
Hammer Data :140 lb, 30" drop, rope and
cathead
USCS SymbolTPSL
Fill
SM Moisture (%)10
12
16
11Recovery (%)Graphic LogRQD (%)MATERIAL DESCRIPTION
Topsoil
Light to dark brown silty SAND with some gravel, medium dense, moist (Fill)
23% fines
Becomes gray to brown, very dense, contains organics
Gray to brown silty SAND with some gravel, very dense, moist
Boring terminated at 16' 5"Depth (feet)0
5
10
15 Sample TypeSampling Resistance, blows/ft21
21
71
90/11"Elevation (feet)Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Family First Community Center
Project Number:2018-130
Client:City of Renton
Boring No.:B-3
Date(s) Drilled:5/23/2018
Drilling Method(s):Hollow Stem Auger
Drill Rig Type:Track Rig
Groundwater Level:Seepage at 15'
Borehole Backfill:Bentonite Chips
Logged By:ELW
Drill Bit Size/Type:8" auger
Drilling Contractor:Bortec
Sampling Method(s):SPT
Location:16022 116th Avenue Southeast, Renton, Washington
Surface Conditions:Grass
Total Depth of Borehole:15.75 feet bgs
Approximate
Surface Elevation:N/A
Hammer Data :140 lb, 30" drop, rope and
cathead
USCS SymbolTPSL
Fill
SM
SP-SM Moisture (%)11
13
11
17Recovery (%)Graphic LogRQD (%)MATERIAL DESCRIPTION
Topsoil
Gray silty SAND with some gravel, medium dense, wet (Fill)
Gray silty SAND with some gravel, very dense, moist to wet (Glacial Till)
Becomes moist
Brown SAND with some silt and gravel, very dense, water bearing
Boring terminated at 15' 9"Depth (feet)0
5
10
15 Sample TypeSampling Resistance, blows/ft12
50/5"
50/6"
50/3"Elevation (feet)Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Family First Community Center
Project Number:2018-130
Client:City of Renton
Boring No.:B-4
Date(s) Drilled:5/23/2018
Drilling Method(s):Hollow Stem Auger
Drill Rig Type:Track Rig
Groundwater Level:Not Encountered
Borehole Backfill:Bentonite Chips
Logged By:ELW
Drill Bit Size/Type:8" auger
Drilling Contractor:Bortec
Sampling Method(s):SPT
Location:16022 116th Avenue Southeast, Renton, Washington
Surface Conditions:Grass
Total Depth of Borehole:15.5 feet bgs
Approximate
Surface Elevation:N/A
Hammer Data :140 lb, 30" drop, rope and
cathead
USCS SymbolTPSL
Fill
SM Moisture (%)12
9
9
10Recovery (%)Graphic LogRQD (%)MATERIAL DESCRIPTION
Topsoil
Brown silty SAND, medium dense, moist
Becomes dense
Gray silty SAND with some gravel, dense, moist (Glacial Till)
Becomes tan, very dense
Boring terminated at 15' 6"Depth (feet)0
5
10
15 Sample TypeSampling Resistance, blows/ft38
43
50/4"
50/6"Elevation (feet)Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Family First Community Center
Project Number:2018-130
Client:City of Renton
Boring No.:B-5
Date(s) Drilled:5/23/2018
Drilling Method(s):Hollow Stem Auger
Drill Rig Type:Track Rig
Groundwater Level:Not Encountered
Borehole Backfill:Bentonite Chips
Logged By:ELW
Drill Bit Size/Type:8" auger
Drilling Contractor:Bortec
Sampling Method(s):SPT
Location:16022 116th Avenue Southeast, Renton, Washington
Surface Conditions:Grass
Total Depth of Borehole:15.42 feet bgs
Approximate
Surface Elevation:N/A
Hammer Data :140 lb, 30" drop, rope and
cathead
USCS SymbolTPSL
SM Moisture (%)12
9
14
7Recovery (%)Graphic LogRQD (%)MATERIAL DESCRIPTION
Topsoil
Gray silty SAND with trace gravel, medium dense, moist to wet (Glacial Till)
31% fines
Becomes very dense
Becomes moist
Boring terminated at 15' 5"Depth (feet)0
5
10
15 Sample TypeSampling Resistance, blows/ft25
61
50/6"
50/5"Elevation (feet)Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Family First Community Center
Project Number:2018-130
Client:City of Renton
Boring No.:B-6
Date(s) Drilled:5/23/2018
Drilling Method(s):Hollow Stem Auger
Drill Rig Type:Track Rig
Groundwater Level:Not Encountered
Borehole Backfill:Bentonite Chips
Logged By:ELW
Drill Bit Size/Type:8" auger
Drilling Contractor:Bortec
Sampling Method(s):SPT
Location:16022 116th Avenue Southeast, Renton, Washington
Surface Conditions:Grass
Total Depth of Borehole:16.5 feet bgs
Approximate
Surface Elevation:N/A
Hammer Data :140 lb, 30" drop, rope and
cathead
USCS SymbolTPSL
SM
SM
SP-SM Moisture (%)12
14
9
9Recovery (%)Graphic LogRQD (%)MATERIAL DESCRIPTION
Topsoil
Tan silty SAND with some gravel, medium dense, moist
Becomes medium dense to dense, little recovery
Becomes medium dense, mottled
Gray silty SAND with some gravel, very dense, moist
Brown SAND with some silt and gravel, very dense, moist to wet
Boring terminated at 16.5'Depth (feet)0
5
10
15 Sample TypeSampling Resistance, blows/ft30
17
67
73Elevation (feet)Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Family First Community Center
Project Number:2018-130
Client:City of Renton
Boring No.:B-7
Date(s) Drilled:5/23/2018
Drilling Method(s):Hollow Stem Auger
Drill Rig Type:Track Rig
Groundwater Level:Not Encountered
Borehole Backfill:Bentonite Chips
Logged By:ELW
Drill Bit Size/Type:8" auger
Drilling Contractor:Bortec
Sampling Method(s):SPT
Location:16022 116th Avenue Southeast, Renton, Washington
Surface Conditions:Grass
Total Depth of Borehole:16.5 feet bgs
Approximate
Surface Elevation:N/A
Hammer Data :140 lb, 30" drop, rope and
cathead
USCS SymbolTPSL
Fill
SM
SM Moisture (%)16
16
22
14Recovery (%)Graphic LogRQD (%)MATERIAL DESCRIPTION
Topsoil
Brown silty SAND with some gravel, loose moist to wet (Fill)
Becomes medium dense, contains organics
33% fines
Brown to gray silty SAND with trace gravel, medium dense, moist to wet
Gray silty SAND with some gravel, medium dense, wet
Boring terminated at 16.5'Depth (feet)0
5
10
15 Sample TypeSampling Resistance, blows/ft7
24
12
22Elevation (feet)Sheet 1 of 1
The Riley Group, Inc.
17522 Bothell Way NE, Bothell, WA 98011
Project Name:Family First Community Center
Project Number:2018-130
Client:City of Renton
Key to Log of Boring
USCS SymbolMoisture (%)Recovery (%)Graphic LogRQD (%)MATERIAL DESCRIPTIONDepth (feet)Sample TypeSampling Resistance, blows/ftElevation (feet)1 2 3 4 5 6 7 8 9 10
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 Sampling Resistance, blows/ft: Number of blows to advance driven
sampler one foot (or distance shown) beyond seating interval
using the hammer identified on the boring log.
5 RQD (%): Rock Quality Designation is a relative index of the rock
mass quality calculated by comparing the cumulative length of
intact pieces of core exceeding 100 mm in length to the cored
interval length.
6 Recovery (%): Core Recovery Percentage is determined based on
a ratio of the length of core sample recovered compared to the
cored interval length.
7 USCS Symbol: USCS symbol of the subsurface material.
8 Graphic Log: Graphic depiction of the subsurface material
encountered.
9 MATERIAL DESCRIPTION: Description of material encountered.
May include consistency, moisture, color, and other descriptive
text.
10 Moisture (%): Moisture, expressed as a water content.
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
Asphaltic Concrete (AC)
AF
Poorly graded GRAVEL (GP)
Silty SAND (SM)
Poorly graded SAND with Silt (SP-SM)
Topsoil
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 Family First Community Center SAMPLE ID/TYPE B-1
PROJECT NO.2018-130 SAMPLE DEPTH 11 Feet
TECH/TEST DATE LC 5/28/2018 DATE RECEIVED 5/28/2018
WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture
Wt Wet Soil & Tare (gm) (w1)385.8 Weight Of Sample (gm)349.2
Wt Dry Soil & Tare (gm) (w2)349.2 Tare Weight (gm) 15.8
Weight of Tare (gm) (w3)15.8 (W6) Total Dry Weight (gm) 333.4
Weight of Water (gm) (w4=w1-w2) 36.6 SIEVE ANALYSIS
Weight of Dry Soil (gm) (w5=w2-w3) 333.4 Cumulative
Moisture Content (%) (w4/w5)*100 11 Wt Ret (Wt-Tare) (%Retained)% PASS
+Tare {(wt ret/w6)*100}(100-%ret)
% COBBLES 0.0 12.0"15.8 0.00 0.00 100.00 cobbles
% C GRAVEL 7.4 3.0"15.8 0.00 0.00 100.00 coarse gravel
% F GRAVEL 10.9 2.5" coarse gravel
% C SAND 6.0 2.0" coarse gravel
% M SAND 17.0 1.5"15.8 0.00 0.00 100.00 coarse gravel
% F SAND 36.8 1.0" coarse gravel
% FINES 21.8 0.75"40.6 24.80 7.44 92.56 fine gravel
% TOTAL 100.0 0.50" fine gravel
0.375"57.4 41.60 12.48 87.52 fine gravel
D10 (mm)#4 77.1 61.30 18.39 81.61 coarse sand
D30 (mm)#10 97.2 81.40 24.42 75.58 medium sand
D60 (mm)#20 medium sand
Cu #40 153.9 138.10 41.42 58.58 fine sand
Cc #60 fine sand
#100 245.5 229.70 68.90 31.10 fine sand
#200 276.6 260.80 78.22 21.78 fines
PAN 349.2 333.40 100.00 0.00 silt/clay
322 306.2 91.841632 8.15836833
DESCRIPTION Silty SAND with some gravel
USCS SM
Prepared For: City of Renton Reviewed By: ELW
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 Family First Community Center SAMPLE ID/TYPE B-2
PROJECT NO.2018-130 SAMPLE DEPTH 2.5 Feet
TECH/TEST DATE LC 5/28/2018 DATE RECEIVED 5/28/2018
WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture
Wt Wet Soil & Tare (gm) (w1)278.1 Weight Of Sample (gm)255.1
Wt Dry Soil & Tare (gm) (w2)255.1 Tare Weight (gm) 15.5
Weight of Tare (gm) (w3)15.5 (W6) Total Dry Weight (gm) 239.6
Weight of Water (gm) (w4=w1-w2) 23.0 SIEVE ANALYSIS
Weight of Dry Soil (gm) (w5=w2-w3) 239.6 Cumulative
Moisture Content (%) (w4/w5)*100 10 Wt Ret (Wt-Tare) (%Retained)% PASS
+Tare {(wt ret/w6)*100}(100-%ret)
% COBBLES 0.0 12.0"15.5 0.00 0.00 100.00 cobbles
% C GRAVEL 15.9 3.0"15.5 0.00 0.00 100.00 coarse gravel
% F GRAVEL 7.6 2.5" coarse gravel
% C SAND 8.6 2.0" coarse gravel
% M SAND 18.0 1.5"15.5 0.00 0.00 100.00 coarse gravel
% F SAND 27.2 1.0" coarse gravel
% FINES 22.6 0.75"53.6 38.10 15.90 84.10 fine gravel
% TOTAL 100.0 0.50" fine gravel
0.375"57.3 41.80 17.45 82.55 fine gravel
D10 (mm)#4 71.9 56.40 23.54 76.46 coarse sand
D30 (mm)#10 92.5 77.00 32.14 67.86 medium sand
D60 (mm)#20 medium sand
Cu #40 135.7 120.20 50.17 49.83 fine sand
Cc #60 fine sand
#100 182.5 167.00 69.70 30.30 fine sand
#200 200.9 185.40 77.38 22.62 fines
PAN 255.1 239.60 100.00 0.00 silt/clay
322 306.5 127.92154 -27.921536
DESCRIPTION Silty SAND with some gravel
USCS SM
Prepared For: City of Renton Reviewed By: ELW
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 Family First Community Center SAMPLE ID/TYPE B-5
PROJECT NO.2018-130 SAMPLE DEPTH 2.5 Feet
TECH/TEST DATE LC 5/28/2018 DATE RECEIVED 5/28/2018
WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture
Wt Wet Soil & Tare (gm) (w1)380.6 Weight Of Sample (gm)340.3
Wt Dry Soil & Tare (gm) (w2)340.3 Tare Weight (gm) 15.8
Weight of Tare (gm) (w3)15.8 (W6) Total Dry Weight (gm) 324.5
Weight of Water (gm) (w4=w1-w2) 40.3 SIEVE ANALYSIS
Weight of Dry Soil (gm) (w5=w2-w3) 324.5 Cumulative
Moisture Content (%) (w4/w5)*100 12 Wt Ret (Wt-Tare) (%Retained)% PASS
+Tare {(wt ret/w6)*100}(100-%ret)
% COBBLES 0.0 12.0"15.8 0.00 0.00 100.00 cobbles
% C GRAVEL 0.0 3.0"15.8 0.00 0.00 100.00 coarse gravel
% F GRAVEL 8.8 2.5" coarse gravel
% C SAND 5.2 2.0" coarse gravel
% M SAND 17.0 1.5"15.8 0.00 0.00 100.00 coarse gravel
% F SAND 37.9 1.0" coarse gravel
% FINES 31.2 0.75"15.8 0.00 0.00 100.00 fine gravel
% TOTAL 100.0 0.50" fine gravel
0.375"22.3 6.50 2.00 98.00 fine gravel
D10 (mm)#4 44.3 28.50 8.78 91.22 coarse sand
D30 (mm)#10 61.2 45.40 13.99 86.01 medium sand
D60 (mm)#20 medium sand
Cu #40 116.3 100.50 30.97 69.03 fine sand
Cc #60 fine sand
#100 205.4 189.60 58.43 41.57 fine sand
#200 239.2 223.40 68.84 31.16 fines
PAN 340.3 324.50 100.00 0.00 silt/clay
322 306.2 94.360555 5.6394453
DESCRIPTION Silty SAND with trace gravel
USCS SM
Prepared For: City of Renton Reviewed By: ELW
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 Family First Community Center SAMPLE ID/TYPE B-7
PROJECT NO.2018-130 SAMPLE DEPTH 5 Feet
TECH/TEST DATE LC 5/28/2018 DATE RECEIVED 5/28/2018
WATER CONTENT (Delivered Moisture) Total Weight Of Sample Used For Sieve Corrected For Hygroscopic Moisture
Wt Wet Soil & Tare (gm) (w1)712.1 Weight Of Sample (gm)618.1
Wt Dry Soil & Tare (gm) (w2)618.1 Tare Weight (gm) 15.7
Weight of Tare (gm) (w3)15.7 (W6) Total Dry Weight (gm) 602.4
Weight of Water (gm) (w4=w1-w2) 94.0 SIEVE ANALYSIS
Weight of Dry Soil (gm) (w5=w2-w3) 602.4 Cumulative
Moisture Content (%) (w4/w5)*100 16 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 4.6 3.0"15.7 0.00 0.00 100.00 coarse gravel
% F GRAVEL 19.5 2.5" coarse gravel
% C SAND 9.1 2.0" coarse gravel
% M SAND 13.6 1.5"15.7 0.00 0.00 100.00 coarse gravel
% F SAND 20.6 1.0" coarse gravel
% FINES 32.6 0.75"43.4 27.70 4.60 95.40 fine gravel
% TOTAL 100.0 0.50" fine gravel
0.375"120.9 105.20 17.46 82.54 fine gravel
D10 (mm)#4 161.1 145.40 24.14 75.86 coarse sand
D30 (mm)#10 216.1 200.40 33.27 66.73 medium sand
D60 (mm)#20 medium sand
Cu #40 297.8 282.10 46.83 53.17 fine sand
Cc #60 fine sand
#100 387.2 371.50 61.67 38.33 fine sand
#200 421.9 406.20 67.43 32.57 fines
PAN 618.1 602.40 100.00 0.00 silt/clay
322 306.3 50.846614 49.1533865
DESCRIPTION Silty SAND with some gravel
USCS SM
Prepared For: City of Renton Reviewed By: ELW
0
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0.0010.010.11101001000
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S
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Grain size in millimeters
12"3" 2" 1" .75" .375" #4 #10 #20 #40 #60 #100 #200