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Proposal Cover PagReport Cover Page
Ryder LC-0549 Fuel
System
Geotechnical Engineering Report
Tukwila, Washington
May 23, 2025 | Terracon Project No. 81255059
Prepared for:
Ryder System, Inc.
306 Sycamore Ave
Eaton, CO 80615
21905 64th Ave. W, Suite 100
Mountlake Terrace, WA 98043
P (425) 771 3304
Terracon.com
Facilities | Environmental | Geotechnical | Materials
Report Cover Letter to Sign May 23, 2025
Ryder System, Inc.
306 Sycamore Ave
Eaton, CO 80615
Attn: Tarah Winterfeld – Environmental Engineer
P: (970) 817-4502
E: tarah_winterfeld@ryder.com
Re: Geotechnical Engineering Report
Ryder LC-0549 Fuel System
17850 West Valley Hwy
Tukwila, WA
Terracon Project No. 81255059
Dear Ms. Winterfeld:
We have completed the scope of services for the above referenced project in general
accordance with Terracon Proposal No. P81255059 dated March 9, 2025. This report
presents the findings of the subsurface exploration and provides geotechnical
recommendations concerning earthwork and the design and construction of foundations
and floor slabs for the proposed project.
We appreciate the opportunity to be of service to you on this project. If you have any
questions concerning this report or if we may be of further service, please contact us.
Sincerely,
Terracon
Baylee A. Sergent, G.I.T. Steven Van Shaar, P.E.
Senior Staff Geologist Senior Engineer
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials i
Table of Contents
Report Summary .............................................................................................. i
Introduction .................................................................................................... 1
Project Description .......................................................................................... 1
Site Conditions ................................................................................................ 3
Geotechnical Characterization ......................................................................... 4
Subsurface Conditions ............................................................................... 4
Mapped Surface Geology ............................................................................ 5
Groundwater Conditions ............................................................................. 5
Seismic Site Class and Hazards ........................................................................ 6
Ground Motion ......................................................................................... 6
Surface-Fault Rupture ............................................................................... 6
Liquefaction ............................................................................................. 7
Geophysical Results ........................................................................................ 7
Geophysical Limitations ............................................................................. 7
Geotechnical Overview .................................................................................... 8
Earthwork ....................................................................................................... 9
Existing Fill .............................................................................................. 9
Site Preparation....................................................................................... 10
Fill Material Types .................................................................................... 10
Fill Placement and Compaction Requirements ............................................... 12
Utility Trench Backfill ............................................................................... 12
Grading and Drainage ............................................................................... 13
Earthwork Construction Considerations ....................................................... 13
Construction Observation and Testing ......................................................... 14
Wet Weather Earthwork ............................................................................ 15
Shallow Foundations ..................................................................................... 15
Design Parameters – Compressive Loads ..................................................... 16
Design Parameters – Overturning Loads ...................................................... 17
Foundation Construction Considerations ...................................................... 17
Pavements .................................................................................................... 18
Pavement Design Parameters .................................................................... 18
Pavement Sections ................................................................................... 18
Pavement Drainage .................................................................................. 20
Pavement Maintenance ............................................................................. 20
General Comments ........................................................................................ 21
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials ii
Attachments
Exploration and Testing Procedures
Photography Log
Site Location and Exploration Plans
Exploration and Laboratory Results
Supporting Information
Note: This report was originally delivered in a web-based format. Blue Bold text in the
report indicates a referenced section heading. The PDF version also includes hyperlinks
which direct the reader to that section and clicking on the logo will bring you
back to this page. For more interactive features, please view your project online at
client.terracon.com.
Refer to each individual Attachment for a listing of contents.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials i
Report Summary
Topic 1 Overview Statement 2
Project Description
The proposed improvements associated with the project include
a new, 15,000-gallon, diesel above-ground storage tank (AST)
with a new concrete tank pad and diesel pipeline. The proposed
tank pad will be 8-inches thick with the dimensions of 40 by 17
feet.
The project also includes the closure of the existing
underground storage tank (UST) and the removal of the
existing;
■ concrete tank pad,
■ fuel island pavement, and
■ associated island equipment and underground utilities.
The existing canopy and canopy columns for the existing fuel
island are anticipated to remain in place.
Geotechnical
Characterization
A layer of asphalt approximately 3 inches thick was observed
at the top of the boreholes. A summary of subsurface findings
at our exploration locations are presented below:
◼ Fill: Existing undocumented fill comprised of medium
dense to dense silty sand and silty gravel was
encountered to depths of approximately 4 and 7 feet at
B-01 and B-02, respectively.
◼ Upper Alluvium: very soft to medium stiff, low
plasticity silt, organic silt, and very loose to medium
dense. This unit underlies fill soils and extends to a depth
of approximately 37 feet.
◼ Lower Alluvium: Medium dense to dense sand with
variable silt content. This unit underlies the Upper
Alluvium and extends to the maximum exploration depth
of 51½ feet.
Groundwater was observed at a depth of approximately 6 feet.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials ii
Seismic
Considerations
The Seismic Site Class is F due to the site-wide liquefaction
hazard. Ground motion values provided assuming the structure
has a fundamental period of vibration equal to, or less than, 0.5
seconds per the Exception in Section 20.2.1 of ASCE 7. The
fundamental period of vibration should be verified by the
structural engineer.
The total seismic-induced settlement is estimated to be about
13 inches. Post-liquefaction differential settlements are
estimated to be about 6 inches over a distance of 100 feet.
Earthwork
■ The subgrade will need to be overexcavated 2 feet below
foundations and replaced with compacted Structural Fill.
■ Scarify the upper 1-foot of soil below the proposed base
of the pavement section (i.e. below the crushed
surfacing base course). Recompact the scarified soil
and/or restore grades with compacted Common or
Structural Fill in pavement areas.
■ If deleterious materials are observed, or areas are
observed to be deflecting excessively, perform additional
removal per Terracon’s field recommendations at the
time of construction.
■ Near-surface soils contain a high silt content and are
moisture sensitive. Subgrades may become unstable
when exposed to excessive moisture.
■ Utility trench stability may be impacted by the presence
of very loose/soft on-site soils and relatively shallow
groundwater. The utility subcontractor should be
prepared to contend with these conditions.
■ Excavated on-site soil (Soil Layer 1) may be selectively
reused as fill below pavement, in utility trenches, or in
landscaping areas. Excavated on-site soil is not suitable
for reuse as Structural Fill and should not be placed
beneath settlement sensitive structures nor within
foundation bearing zones.
Shallow
Foundations
A mat foundation is recommended for support of the AST.
■ Allowable bearing pressure = 500 psf
■ Expected static settlements: < 1-inch total, < ¾-inch
differential
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials iii
Pavements
(provided in
preliminary civil site
plans)
With subgrade prepared as noted in Earthwork recommended
new pavement replacement sections are:
Asphalt:
■ Light Duty: 4” HMA over 8” granular base
■ Heavy Duty: 6” HMA over 8” granular base
Concrete:
■ 6” PCC over 8” granular base
General Comments This section contains important information about the
limitations of this geotechnical engineering report.
1. If the reader is reviewing this report as a pdf, the topics above can be used to access the
appropriate section of the report by simply clicking on the topic itself.
2. This summary is for convenience only. It should be used in conjunction with the entire
report for design purposes.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 1
Introduction
This report presents the results of our subsurface exploration and geotechnical engineering
services performed for the proposed AST to be located at 17850 West Valley Hwy in
Tukwila, WA. The purpose of these services was to provide information and geotechnical
engineering recommendations relative to:
■ Subsurface soil and groundwater conditions
■ Seismic considerations and liquefaction
■ Geophysical results
■ Site preparation and earthwork
■ Foundation design and construction
■ Floor slab design and construction
■ Subsurface drainage
■ Pavement design and construction
The geotechnical engineering Scope of Services for this project included the advancement
of test borings, laboratory testing, engineering analysis, and preparation of this report.
Drawings showing the site and boring locations are shown on the Site Location and
Exploration Plan, respectively. The results of the laboratory testing performed on soil
samples obtained from the site during our field exploration are included on the boring logs
and/or as separate graphs in the Exploration Results section.
Project Description
Our initial understanding of the project was provided in our proposal and was discussed
during project planning. A period of collaboration has transpired since the project was
initiated, and our current understanding of the project conditions is as follows:
Item Description
Information
Provided
■ Email request for proposal prepared by Ryder dated March
6, 2025
■ Preliminary civil site plans dated January 31, 2025
■ Existing Fuel System Sketch dated September 10, 2024
■ Updated tank pad dimensions via email correspondence
with Ryder dated March 26, 2025
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 2
Item Description
Project
Description
Renovations of the Ryder fueling facility include a new AST,
concrete tank pad, associated utilities, and partial pavement
replacement.
The existing canopy and canopy columns for the existing fuel
island are anticipated to remain in place.
Proposed
Improvements
The proposed improvements associated with the project include:
■ New, 15,000-gallon, double wall, steel, diesel AST tank on
a 40 feet by 17 foot concrete pad
■ new diesel master piping extending from the existing fuel
island to the new AST
■ new asphalt pavement will be placed over the proposed
pipeline covering a length of approximately 69½ feet.
■ new concrete pavement is proposed within the existing fuel
island, covering an area of approximately 1,240 square
feet.
Finished Floor
Elevation
Finished floor elevations are anticipated to be at or near existing
grades.
Maximum Loads
(Assumed)
Anticipated structural loads were not provided. In the absence of
information provided by the design team, loads will be
approximated based on weight of a full, 15,000 gallon, cylindrical,
UL 2085 Fireguard® AST:
■ Approximately 141,000 pounds
Pavements
(provided in
preliminary civil site
plans)
Both rigid (concrete) and flexible (asphalt) pavement sections will
be considered. The following traffic design estimates for flexible
pavements are presented as equivalent single axle loads (ESALs):
■ Car parking 10 ESALs daily
■ Truck parking 50 ESALs daily
■ Other areas 150 ESALs daily
The pavement design period is 15 years.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 3
Item Description
Building Code(s)
The following design codes are assumed:
■ International Building code – Version 2021 (2021 IBC)
■ ASCE 7-22 for seismic considerations
Terracon should be notified if any of the above information is inconsistent with the
planned construction as modifications to our recommendations may be necessary.
Site Conditions
The following description is derived from our site visit in association with the field
exploration and our review of publicly available geologic and topographic maps.
Item Description
Parcel
Information
The project is located at 17850 West Valley Hwy in Tukwila, WA.
Lot Size: ~2.6 acres
Property Tax Parcel No.: 3623049062
Latitude (approximate): 47.4430° N
Longitude (approximate): 122.2427° W See Site Location
Existing
Improvements
Existing improvements consist of the Ryder Truck Rental building
to the west of the proposed improvement area.
The proposed improvement area of the site is currently occupied
by a fuel island consisting of two diesel USTs, two dual master
dispensers, four satellite dispensers, and associated underground
product lines within and around a canopy. The site is surrounded
by concrete and asphalt paved driveways and parking areas.
Current Ground
Cover
Groundcover within the proposed AST area currently consists of
asphalt pavement. The existing fuel island and UST areas are
paved with concrete.
Existing
Topography
Based on elevations provided in the ALTA/NSPS Land Title Survey
prepared by Navix Engineering and dated July 12, 2019, the site
appears to be relatively level within the project boundary.
Elevations of the pavement surface appear to vary between
approximately 27 to 28 feet.
Photography Log Sample photos from the site are provided in our Photography
Log.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 4
Geotechnical Characterization
Subsurface Conditions
We have developed a general characterization of the subsurface conditions based upon
our review of the subsurface exploration, laboratory data, geologic setting, and our
understanding of the project. This characterization, termed GeoModel, forms the basis of
our geotechnical calculations and evaluation of the site. Conditions observed at each
exploration point are indicated on the individual logs. The individual logs and the GeoModel
can be found in the Exploration Results section of this report.
Soil
Layer1
Layer
Name USCS General Description
--- Surface --- Approximately 3 inches of asphalt pavement.
1 Fill SM, GM
Fill soils comprised of silty gravel with sand or silty
sand with gravel.
◼ Fine to coarse grained, brownish gray, medium
dense to dense.
◼ Observed to depths between 4 and 7 feet below
ground surface (bgs).
2 Upper
Alluvium
ML, OL,
SM
This unit underlies the fill soils and was observed to
extend to a depth of approximately 37 feet bgs. This
unit contains variable organic content and is comprised
of;
◼ Silt with variable sand and gravel content and
organic silt, low plasticity, gray to dark brown,
very soft to medium stiff.
◼ Silty sand with variable gravel content, fine
grained, gray to dark gray, very loose to
medium dense. Interbeds of silt observed
throughout.
3 Lower
Alluvium
SM, SP,
SP-SM
This unit underlies the Upper Alluvium and was
observed to extend to the maximum exploration depth
of roughly 51½ feet bgs. This unit is comprised of;
◼ Poorly graded sand with variable silt content and
silty sand, fine to medium grained, gray to dark
gray, medium dense to dense. Interbeds of silt
observed.
1. This summary is for convenience only. It should be used in conjunction with the entire
report.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 5
Mapped Surface Geology
Terracon performed a geotechnical exploration involving two soil borings to a maximum
depth of approximately 31 feet for the renovation of the existing Ryder facility in 2019.
The historic boring logs are attached in the Supporting Information of this report.
Our experience from the previous exploration and our review of geologic maps and other
nearby geotechnical data indicates subsurface conditions consist of Quaternary age alluvial
sand, silt, clay, and peat1 overlain by fill. Based on observations made during the
subsurface investigation, the soils encountered at the project location appear to be
consistent with published records and geologic conditions encountered previously.
Groundwater Conditions
The explorations were observed during advancement for the presence and level of groundwater.
Groundwater was encountered during auger advancement at boring B-02 at a depth of
approximately 6 feet bgs. The 2019 geotechnical exploration encountered groundwater at 4
and 14 feet at historical boring locations B-01 and B-02, respectively. Mapping by the Natural
Resources Conservation Service (NRCS) indicates a seasonal high groundwater level may
be within 6 inches of the ground surface.
Ponded water was observed approximately 25 feet to the northeast of boring location B-01. The
surface of the water in the pond was roughly 2 feet below current pavement grade (approx.
elevation 26½ feet). Water level measurement was not attempted at boring B-01 during drilling
due to the mud rotary method of boring advancement. However, we anticipate that water levels
will be approximately equivalent to the depth to the surface of the pond from the ground surface
elevation at B-01.
Groundwater level fluctuations occur due to seasonal variations in the amount of rainfall,
runoff and other factors not evident at the time the borings were performed. Therefore,
groundwater levels during construction or at other times in the life of the structure may
be higher or lower than the levels indicated on the boring logs. The possibility of
groundwater level fluctuations should be considered when developing the design and
construction plans for the project.
1 Mullineaux, D. R., 1965, Geologic map of the Renton quadrangle, King County, Washington:
U.S. Geological Survey, Geologic Quadrangle Map GQ-405, 1 sheet, scale 1:24,000.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 6
Seismic Site Class and Hazards
Ground Motion
In 2024, the State of Washington adopted the 2021 IBC allowing the Multi-Period Response
Spectrum (MPRS) of ASCE 7-22 for determination of design ground motion values. The
amendment requires use of the updated Site Class designations found in Chapter 20 of
ASCE 7-22. The MPRS values were obtained from the ASCE 7-22 online tool
(https://asce7hazardtool.online/) and are presented in the below table.
Description Value 1
ASCE 7-22 Site Classification2 F
Site Latitude 47.4430° North
Site Longitude 122.2427° West
SS – Short Period Spectral Acceleration 1.63 g
S1 – 1-Second Period Spectral Acceleration 0.53 g
SMS – Short Period Spectral Acceleration
Adjusted for Site Class 1.69 g
SM1 – 1-Second Spectral Acceleration
Adjusted for Site Class 1.31 g
SDS – Design Short Period Spectral Acceleration 1.13 g
SD1 – Design 1-Second Spectral Acceleration 0.87 g
PGAM - ASCE 7, Peak Ground Acceleration Adjusted for Site
Class 0.68 g
1. The IBC requires a site profile extending to a depth of 100 feet for seismic site
classification. Borings were extended to a maximum depth of 51½ feet. We performed one
Shear Wave Velocity Test at the site to measure shear wave velocities within the upper 100 feet
of the subsurface materials at the site. The approximate weighted average shear wave velocity
was 590 ft/sec.
2. Site Class F is because of liquefiable soils. Ground motion values provided assuming the
structure has a fundamental period of vibration equal to, or less than, 0.5 seconds per the
Exception in Section 20.2.1 of ASCE 7. The fundamental period of vibration should be verified
by the structural engineer.
Surface-Fault Rupture
The hazard of damage from onsite fault rupture appears to be low based on review of the
USGS Earthquake Hazards Program Quaternary Faults and Folds Database available online
(https://usgs.maps.arcgis.com/apps/webappviewer/index.html?id=5a6038b3a168456
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 7
1a9b0aadf88412fcf) accessed on April 30, 2025. The closest mapped fault is a thrust fault
within the Seattle Fault Zone, which lies approximately 6 miles to the North, and has an
average slip rate between 0.2 and 1.0 mm/yr.
Liquefaction
Liquefaction is the phenomenon where saturated soils develop high pore water pressures
during seismic shaking and lose their strength characteristics. This phenomenon generally
occurs where the magnitude of seismic shaking is high, groundwater is shallow, and loose
granular soils or relatively non-plastic fine-grained soils are present. Based on the site
geology and subsurface groundwater conditions, the hazard of liquefaction of the site soils is
high for this site during a design level earthquake and is most likely to occur between
approximately 6 and 36 feet below the ground surface. This zone generally lies between the
groundwater table and the bottom of the Upper Alluvium unit. The site is relatively flat, and the
likelihood of lateral spreading is low.
Liquefaction analysis of the SPT data obtained was performed using software LiqSVs developed
by Geologismiki. For consideration of liquefiable soils in the upper 50 feet, we computed free-
field, seismic-induced total settlements of approximately 13 inches. We estimate maximum
differential settlements of about 6 inches over a distance of 100 feet.
Geophysical Results
Terracon performed seismic testing to estimate the average shear wave velocity to aid in
seismic site classification and liquefaction characterization. The test location is shown in
the Exploration Plan. The geophysical test method is described in Exploration and
Testing Procedures.
The shear wave data collected during the test was processed and modeled to yield a 1-
Dimensional (1D) line graph depicting shear wave velocity with depth and a weighted
average shear wave velocity for the top 100 ft (Vs100). The profile can be found in
the Exploration and Laboratory Results section of this report. The shear wave testing
indicated an average velocity for the top 100 ft to be about 590 ft/sec.
Geophysical Limitations
These processes rely on measured responses to provide indications of physical conditions
in the field. Responses can be affected by on-site conditions beyond the control of the
operator, such as, but not limited to, cultural features (e.g., utilities, buried metallic
objects, etc.), soil/material types, soil/material moisture, and/or groundwater table depth.
Interpretation is based on known factors combined with the experience of the operator
and the geophysicist evaluating the results. As with all geophysical methods, the
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 8
geophysical results provide information regarding subsurface conditions at the site but
should not be considered absolute. We cannot be responsible for the interpretation of
geophysical results by others.
Geotechnical Overview
On March 31, 2025, two soil borings were advanced within the site to the maximum depth
of approximately 51½ feet below ground surface (bgs). Soils observed at the time of
drilling generally consisted of approximately 4 to 7 feet of existing, undocumented fill soils
(Soil Layer 1) overlying soft to very soft to medium stiff silt or very loose to medium dense
silty sand (Soil Layer 2). At approximately 37 feet, medium dense to dense soils consisting
of sand within variable silt content were encountered (Soil Layer 3). Groundwater was
observed at approximately 6 feet bgs. Seasonal high groundwater levels should be
considered in the civil engineering design for site grading, utility construction, and
pavements.
Based on the results of the subsurface exploration, laboratory testing, and our analyses,
the location of the proposed AST is subject to free-field, vertical displacements during a
design-level seismic event of up to 13 inches. The Seismic Considerations section
presents code-based seismic design parameters as well as a summary of the liquefaction
evaluation. Assuming the structure can be designed to accommodate the large
displacements due to liquefaction, we have provided geotechnical recommendations for
design of a mat foundation. Foundation discussion and recommendations are provided in
the Shallow Foundations section.
Existing uncontrolled fill soils were observed at boring locations B-01 and B-02 to
approximately 4 and 7 feet bgs, respectively, and may extend deeper at other locations.
Construction over existing fill presents inherent risk for the owner that compressible fill or
unsuitable material, within or buried by the fill, will not be discovered. This risk of
unforeseen conditions cannot be eliminated without completely removing the existing fill.
However, development of foundations and pavements over existing fill is feasible provided
the owner is willing to accept the associated risk of erratic and unpredictable settlement
of which can lead to the loss of subgrade support. Even if the owner decides to leave some
existing fill in place, we recommend that fill soils should be excavated to a minimum depth
of 2 feet below foundations and replaced with compacted structural fill. Beneath proposed
pavements we recommend scarifying the upper 1-foot of the soil below the proposed base
of the pavement section (i.e. below the crushed surfacing base course). Recompact the
scarified soil and/or restore grades with compacted Common or Structural Fill as
recommended in the Earthwork section.
The near-surface soils contain a significant fines content (percent passing the #200 sieve);
therefore, these soils will exhibit sensitivity to excessive moisture and/or disturbance and
could become unstable with typical earthwork and construction traffic, especially after a
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 9
precipitation event. Effective drainage should be completed early in the construction
sequence and maintained after construction to avoid potential issues. If possible, the
grading should be performed during the warmer and drier times of the year. If grading is
performed during the winter months, an increased risk for necessary undercutting and
replacement of unstable subgrade will persist. Additional site preparation
recommendations, including subgrade improvement and fill placement, are provided in
the Earthwork section.
Specific conclusions and recommendations regarding these geotechnical considerations,
as well as other geotechnical aspects of design and construction of foundation systems
and other earthwork related phases of the project are outlined in the following sections.
The recommendations contained in this report are based upon the results of field and
laboratory testing, engineering analyses, and our current understanding of the proposed
project. ASTM standards and Washington State Department of Transportation (WSDOT)
specifications cited herein respectively refer to the current manual published by the
American Society for Testing & Materials and the current edition of the Standard
Specifications for Road, Bridge, and Municipal Construction, (M41-10).
The recommendations contained in this report are based upon the results of field and
laboratory testing (presented in the Exploration Results), engineering analyses, and our
current understanding of the proposed project. The General Comments section provides
an understanding of the report limitations.
Earthwork
Earthwork is anticipated to include clearing and grubbing, removal of existing
improvements marked for demolition, excavations for utility trenches, pavements, and
foundations, and engineered fill placement. The following sections provide
recommendations for use in the preparation of specifications for the work.
Recommendations include critical quality criteria, as necessary, to render the site in the
state considered in our geotechnical engineering evaluations.
Existing Fill
As noted in Geotechnical Characterization, previously placed, undocumented fill was
encountered to depths ranging from about 4 to 7 feet at borings B-01 and B-02,
respectively. Support of floor slabs and pavements on or above existing fill soils is
discussed in this report. However, even with the recommended construction procedures,
inherent risk exists for the owner that compressible fill or unsuitable material, within or
buried by the fill, will not be discovered. This risk of unforeseen conditions cannot be
eliminated without completely removing the existing fill but can be reduced by following
the recommendations contained in this report.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials 10
If the owner elects to construct foundations and pavements on the existing fill, the
following protocol should be followed. We recommend overexcavation to a minimum depth
of 2-feet beneath the proposed slab and replacement with compacted Structural Fill.
Beneath proposed pavements we recommend scarifying the upper 1-foot of the soil below
the proposed base of the pavement section (i.e. below the crushed surfacing base course).
If deleterious materials are observed, or areas are observed to be deflecting excessively,
perform additional removal per Terracon’s field recommendations at the time of
construction. Recompact the scarified soil and/or restore grades with compacted Common
or Structural Fill as recommended herein.
Site Preparation
Prior to placing fill, existing pavements and deleterious material should be removed and
the existing, undocumented fill should be overexcavated according to our
recommendations.
All prepared subgrades should be observed by Terracon prior to casting of slab
foundations. As mentioned in Geotechnical Overview section, the near-surface soil
generally contains a significant fines content and could be moisture sensitive. Maintaining
the condition of subgrade after observation by Terracon will be the responsibility of the
contractor.
Fill Material Types
Fill required to achieve design grade should be classified as structural fill and common fill.
Structural fill is material used below, or within 10 feet of structures or pavements.
Common fill is material used to achieve grade outside of these areas.
Import and On-Site Soil: Excavated on-site soil (Soil Layer 1) may be selectively reused
as fill for pavement subgrades, in utility trenches and outside the foundation area if it
meets the requirements for Common Fill in the table below. Excavated on-site soil is not
suitable for reuse as Structural Fill and should not be placed beneath settlement sensitive
structures and within foundation bearing zones. Portions of the on-site soil have an
elevated fines content and will be sensitive to moisture conditions (particularly during
seasonally wet periods) and may not be suitable for reuse when above optimum moisture
content.
Imported fill materials should meet the following material property requirements.
Regardless of its source, compacted fill should consist of approved materials that are free
of organic matter and debris. Frozen material should not be used, and fill should not be
placed on a frozen subgrade.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
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Material property requirements for on-site soil for use as common fill and structural fill
are noted in the table below:
Fill Type Recommended Materials Acceptable Location for
Placement
Structural Fill 2
9-03.9(1) Ballast 1
9-03.9(3) Crushed Surfacing Base
Course 1
9-03.12(1)A Gravel Backfill for
Foundations Class A 1
9-03.14(1) Gravel Borrow 1
Beneath and adjacent to
structural slabs, foundations,
and structural
appurtenances
Common Fill 2
Section 9-03.14(3) Common Borrow 1
On-site Existing Fill Soils (i.e., Soil
Layer 1) 3
Pavement subgrades,
grade filling, utility trench
backfill outside the
foundation and
appurtenances
Free-Draining
Granular Fill
Structural Fill 4
9-03.9(2) Permeable Ballast 1
9-03.12(2) Gravel Backfill for Walls 1
9-03.12(4) Gravel Backfill for Drains 1
Backfilling in wet weather,
drainage layers for walls,
sump drains, footing
drains 5
1. WSDOT Standard Specifications
2. Structural and common fill should consist of approved materials free of organic matter
and debris. Frozen material should not be used, and fill should not be placed on a frozen
subgrade. A sample of each material type should be submitted to the Geotechnical
Engineer for evaluation prior to use on site.
3. May contain local areas of higher fines content that could make this material moisture
sensitive. Particles with a nominal diameter greater than about 3 in. should be removed.
4. Material provided must be specified to be less than 5-percent passing the #200 sieve for
the portion of material passing the #4 sieve.
5. Minimum particle size must be greater than drainpipe perforations.
Other earthen materials may be suitable for use in addition to the options presented in
the table above. All materials should be approved by the Geotechnical Engineer prior to
use.
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Fill Placement and Compaction Requirements
Structural and common fill should meet the following compaction requirements.
Item Structural Fill Common Fill
Maximum Lift
Thickness
8 inches or less in loose thickness when
heavy, self-propelled compaction equipment
is used
4 to 6 inches in loose thickness when hand-
guided equipment (i.e. jumping jack or
plate compactor) is used
Same as
structural fill
Minimum
Compaction
Requirements1
95% of max. dry density below foundations
and within 1 foot of finished pavement
subgrade
92% of max. dry density above foundations
and 1 foot or more below finished pavement
subgrade
92% of maximum
dry density
Water Content
Range1 Granular: -2% to +2% of optimum
As required to
achieve min.
compaction
requirements
1. Maximum density and optimum water content as determined by the Modified Proctor test
(ASTM D 1557).
Utility Trench Backfill
Any soft or unsuitable materials encountered at the bottom of utility trench excavations
should be removed and replaced with structural fill or bedding material in accordance with
public works specifications for the utility be supported. This recommendation is particularly
applicable to utility work requiring grade control and/or in areas where subsequent grade
raising could cause settlement in the subgrade supporting the utility. Trench excavation
should not be conducted below a downward 1:1 projection from existing foundations
without engineering review of shoring requirements and geotechnical observation during
construction.
Granular soils are recommended for trench backfill in structural areas due to their relative
ease of compaction in confined areas as opposed to cohesive soils. The existing
undocumented fill that was removed for utility trench excavation can be evaluated for
reuse as common fill.
Trench backfill should be mechanically placed and compacted as discussed earlier in this
report. Compaction of initial lifts should be accomplished with hand-operated tampers or
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other lightweight compactors. In our opinion, the initial lift thickness should not exceed
on foot unless recommended by the manufacturer to protect utilities from damage by
compacting equipment. Light, hand-operated compaction equipment in conjunction with
thinner fill lift thickness may be used on backfill placed above utilities if damage resulting
from heavier compaction equipment is of concern.
All trenches should be wide enough to allow for compaction around the haunches of the
pipe. We recommend that utility trench excavations be completed using a smooth
excavation bucket (without teeth) to reduce the potential of subgrade disturbance. If
water is encountered in the excavations, it should be removed prior to fill placement.
Flexible connections for utilities that pass through foundations are recommended to reduce
potential stress associated with differential settlement that may occur between the AST
foundation and the improvements located outside of the tank pad footprint.
Grading and Drainage
All grades must provide effective drainage away from the tank pad during and after
construction and should be maintained throughout the life of the structure. Effective
drainage will be essential during construction to limit the extent of soil disturbance during
the wet season.
Water retained next to the structure can result in soil movements greater than those
discussed in this report. Greater movements can result in unacceptable differential
movements and cracked foundations. Gutters and downspouts should be routed into
tightline pipes that discharge either directly into a municipal storm drain or to an
alternative drainage facility. Splash-blocks should also be considered below hose bibs and
water spigots.
Site grades should be established such that surface water is directed away from foundation
and pavement subgrades to prevent an increase in the water content of the soils. Adequate
positive drainage diverting water from structures, open cuts, and slopes should be
established to prevent erosion, ground loss, and instability. Locally, flatter grades may be
necessary to transition ADA access requirements for flatwork. After construction and
landscaping, final grades should be verified to document effective drainage has been
achieved. Where paving or flatwork abuts the structure a maintenance program should be
established to effectively seal and maintain joints and prevent surface water infiltration.
Earthwork Construction Considerations
Shallow excavations for the proposed structure are anticipated to be accomplished with
conventional construction equipment. Upon completion of filling and grading, care should
be taken to maintain the subgrade water content prior to construction of grade-supported
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improvements such as slabs and pavements. Construction traffic over the completed
subgrades should be avoided. The site should also be graded to prevent ponding of surface
water on the prepared subgrades or in excavations. Water collecting over or adjacent to
construction areas should be removed. If the subgrade freezes, desiccates, saturates, or
is disturbed, the affected material should be removed, or the materials should be scarified,
moisture conditioned, and recompacted prior to mat foundation construction.
The groundwater table could affect overexcavation efforts, especially for overexcavation
and replacement of lower strength soils. The nearby pond noted in the Groundwater
Conditions section of this report may contribute to groundwater flow into the excavations.
A temporary dewatering system consisting of sumps with pumps may be necessary to
achieve the recommended depth of overexcavation depending on groundwater conditions
at the time of construction. Specialized equipment and methods may be needed in an
effort to reduce subgrade disturbance. For example, using an excavator (i.e., trackhoe)
rather than a bulldozer to excavate would reduce subgrade disturbance. In addition,
placing fill with a wide-tracked (i.e., low-pressure) bulldozer by pushing the fill over the
subgrade in advance of the equipment will also reduce disturbance. Initial lift thickness
may need to be increased and static rolling, rather than vibratory rolling, may be needed
to prevent “pumping” of subgrade. As a minimum, excavations should be performed in
accordance with OSHA 29 CFR, Part 1926, Subpart P, “Excavations” and its appendices,
and in accordance with any applicable local and/or state regulations.
Construction site safety is the sole responsibility of the contractor who controls the means,
methods, and sequencing of construction operations. Under no circumstances shall the
information provided herein be interpreted to mean Terracon is assuming responsibility
for construction site safety or the contractor's activities; such responsibility shall neither
be implied nor inferred.
Construction Observation and Testing
The earthwork efforts should be observed by the Geotechnical Engineer (or others under
their direction). Observation should include documentation of adequate removal of
surficial materials (vegetation, topsoil, and pavements), evaluation and remediation of
existing fill materials, as well as proofrolling and mitigation of unsuitable areas delineated
by the proofroll.
Each lift of compacted fill should be tested, evaluated, and reworked as necessary until
approved by the Geotechnical Engineer prior to placement of additional lifts. Each lift of
fill should be tested for density and water content.
In areas of foundation excavations, the bearing subgrade should be evaluated by the
Geotechnical Engineer. If unanticipated conditions are observed, the Geotechnical
Engineer should prescribe mitigation options.
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In addition to the documentation of the essential parameters necessary for construction,
the continuation of the Geotechnical Engineer into the construction phase of the project
provides the continuity to maintain the Geotechnical Engineer’s evaluation of subsurface
conditions, including assessing variations and associated design changes.
Wet Weather Earthwork
The near-surface soils have variable fines content based on our visual observations and
lab testing and are considered moisture sensitive. The soils will exhibit moderate erosion
potential and may be transported by running water. Silt fences and other best-
management practices will be necessary to control erosion and sediment transport during
construction.
The suitability of soils used for structural fill depends primarily on their grain-size
distribution and moisture content when they are placed. As the fines content (the soil
fraction passing the U.S. No. 200 Sieve) increases, soils become more sensitive to small
changes in moisture content. Soils containing more than about 5 percent fines (by weight)
cannot be consistently compacted to a firm, unyielding condition when the moisture
content is more than 2 percentage points above or below optimum. Optimum moisture
content is the moisture content at which the maximum dry density for the material is
achieved in the laboratory by the ASTM D1557 test procedure.
If inclement weather or in situ soil moisture content prevents the use of on-site material
as common fill, we recommend use of materials specified in Fill Material Types for free-
draining granular fill. Stockpiled soils should be protected with polyethylene sheeting
anchored to withstand local wind conditions and preservation of the soil’s moisture
content.
Shallow Foundations
Per the variable existing, undocumented fill and anticipated differential seismic
settlements, we recommend a mat foundation for the AST support. Mat foundations are a
type of shallow foundation that uses bearing capacity of the soil at or near the base of a
structure to transmit the loads to the soil. A mat foundation is often used where load and
soil conditions, such as soils subjected to liquefaction, could cause substantial differential
settlement between individual spread footings. If the site has been prepared in accordance
with the requirements noted in Earthwork, the following design parameters are applicable
for shallow foundations.
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Design Parameters – Compressive Loads
Item Description
Maximum Net Allowable
Bearing Pressure 1, 2
500 psf - foundations bearing on 2-feet of
Structural Fill over GeoModel Layer 1 or 2
Ultimate Passive Resistance 3
(equivalent fluid pressures) 400 pcf (granular backfill)
Sliding Resistance 4 0.4 allowable coefficient of friction - granular
material
Minimum Embedment below
Finished Grade 5 18 inches
Estimated Total Settlement
from Structural Loads 2, 7 Less than about 1 inch
Estimated Differential
Settlement 2, 6 About ¾ of total settlement
Estimated Modulus of
Subgrade Reaction 8
K1 = 15 pounds per square inch per inch (psi/in)
KB×B = K1 (𝐵+1
2𝐵)2
KB×L = KB×B (1+0.5 𝐵/𝐿
1.5 )
Where,
K1 = modulus of subgrade reaction for 1 ft × 1 ft slab
KB×B = modulus of subgrade reaction for a square foundation
of B ft
KB×L = modulus of subgrade reaction for a rectangular
foundation of dimensions B×L ft
1. The maximum net allowable bearing pressure is the pressure in excess of the minimum
surrounding overburden pressure at the footing base elevation. An appropriate factor of
safety has been applied. These bearing pressures can be increased by 1/3 for transient
loads unless those loads have been factored to account for transient conditions.
2. Values provided are for maximum loads noted in Project Description. Additional
geotechnical consultation will be necessary if higher loads are anticipated. Assumes
foundation remains 2 feet above groundwater table year-round.
3. Passive resistance in the upper 2 feet of the soil profile should be neglected. Assumes
resisting soil is above the water table.
4. Can be used to compute sliding resistance where foundations are placed on suitable
soil/materials. Should be neglected for foundations subject to net uplift conditions.
5. For frost protection and to reduce the effects of seasonal moisture variations in the
subgrade soils. For sloping ground, maintain depth below the lowest adjacent exterior
grade within 5 horizontal feet of the structure.
6. Differential settlements are as measured over a span of 50 feet. We should review the
settlement estimates after the foundation plan has been prepared by the structural
engineer.
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Item Description
7. The total settlement and differential settlement shown in the table above does not include
potential liquefaction settlement. See the Liquefaction section for the total and
differential seismic-induced settlement.
8. Modulus of subgrade reaction is an estimated value based upon our experience with the
subgrade condition and the requirements noted in Earthwork. Values of modulus of
subgrade reaction are estimated for subgrade conditions consistent with the conditions
for the maximum net allowable bearing pressure given above.
Design Parameters – Overturning Loads
Shallow foundations subjected to overturning loads should be proportioned such that the
location of the resultant force is maintained in the center-third of the foundation (e.g., e
< b/6, where e is eccentricity and b is the foundation width). This requirement is intended
to keep the entire foundation area in compression during the extreme lateral/overturning
load event. Foundation oversizing may be required to satisfy this condition.
Foundation Construction Considerations
As noted in Earthwork, the footing excavations (including recommended over-
excavation) should be evaluated by the Geotechnical Engineer. The base of all foundation
excavations should be free of water and loose soil, prior to placing concrete. Concrete
should be placed soon after excavating to reduce bearing soil disturbance. Care should be
taken to prevent wetting or drying of the bearing materials during construction.
Excessively wet or dry material or any loose/disturbed material in the bottom of the footing
excavations should be removed/reconditioned before foundation concrete is placed.
Overexcavation for structural fill placement below footings should be conducted as shown
below. The overexcavation should be backfilled up to the footing base elevation, with
Structural Fill placed, as recommended in the Earthwork section, or with cementitious
low-strength material (CLSM, also called controlled density fill, CDF). The lean concrete
replacement zone is illustrated on the sketch below.
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Pavements
Pavement Design Parameters
Pavement designs are provided for the traffic conditions and pavement life conditions
noted in Project Description and in the following sections of this report. A critical aspect
of pavement performance is site preparation. Pavement designs noted in this section must
be applied to the site which has been prepared as recommended in the Earthwork section.
A 15-year design life is assumed. A California Bearing Ratio (CBR) of 10 was used for the
subgrade for the asphaltic concrete (AC) pavement designs. Any imported or borrow source
fill placed below the proposed pavements should have a CBR value of at least 10. A modulus
of subgrade reaction of 200 pci was used for the portland cement concrete (PCC) pavement
designs. The value was empirically derived based upon our experience with the silty sand
and silty gravel (Soil Layer 1) subgrade soils and our expectation of the quality of the
subgrade as prescribed by the Site Preparation conditions as outlined in Earthwork.
Pavement Sections
The design of Asphaltic Concrete (AC) pavements are based on the 1993 AASHTO
guidelines. Minimum recommended pavement section thicknesses are presented below:
Asphaltic Concrete (AC) Design
Layer Light Duty Layer
Thickness (inches)
Heavy Duty Layer
Thickness (inches)
Compacted Subgrade 1 12 12
Crushed Aggregate Base 2 8 8
Asphalt Thickness 3, 4 4 6
1. May vary based on observations following proof-rolling.
2. Aggregate base meeting WSDOT:9-03.9(3) Base Course specifications, and the
requirements specified in the Earthwork section.
3. Aggregates for asphalt surface meeting WSDOT: 9-03.8(2) ½-inch HMA requirements.
4. PG58H-22 asphalt binder.
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Portland Cement Concrete (PCC) Design
Layer Layer Thickness (inches)
Compacted Subgrade 1 12
Crushed Aggregate Base 2 8
Portland Cement Concrete Thickness 6
1. May vary based on observations following proof-rolling.
2. Aggregate base meeting WSDOT:9-03.9(3) Base Course specifications, and the
requirements specified in the Earthwork section.
We recommend that Portland cement concrete (PCC, rigid) pavement be used where rigid
pavements are appropriate. These areas include but are not limited to entrance and exit
sections, dumpster pads, or any areas where extensive wheel maneuvering or repeated
loading are expected. The rigid pavement pads should be large enough to support the
wheels of the truck which will bear the haul load. Adequate reinforcement and number of
longitudinal and transverse control joints should be placed in the rigid pavement in
accordance with ACI requirements. Although not required for structural support, the base
course layer is recommended to help reduce potential for slab curl, shrinkage cracking,
subgrade “pumping” through joints, and provide a workable surface. Proper joint spacing
will also be required to prevent excessive slab curling and shrinkage cracking. All joints
should be sealed to prevent entry of foreign material and dowelled where necessary for
load transfer.
The minimum pavement sections outlined above were determined based on post-
construction traffic loading conditions. These pavement sections do not account for heavy
construction traffic during development. A partially constructed structural section that is
subjected to heavy construction traffic can result in pavement deterioration and premature
distress or failure. Our experience indicates that this pavement construction practice can
result in pavements that will not perform as intended. Considering this information,
several alternatives are available to mitigate the impact of heavy construction traffic prior
to pavement construction. These include using thicker sections to account for the
construction traffic after paving; using some method of soil stabilization to improve the
support characteristics of the pavement subgrade; routing heavy construction traffic
around paved areas; or delaying paving operations until as near the end of construction
as is feasible.
Areas for the parking of heavy vehicles, concentrated turn areas, and start/stop
maneuvers could require thicker pavement sections. Edge restraints (i.e. concrete curbs
or aggregate shoulders) should be planned along curves and areas of maneuvering
vehicles.
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Pavement Drainage
Pavements should be sloped to provide rapid drainage of surface water. Water allowed to
pond on or adjacent to the pavements could saturate the subgrade and contribute to
premature pavement deterioration. In addition, the pavement subgrade should be graded
to provide positive drainage within the granular base section. Appropriate sub-drainage or
connection to a suitable daylight outlet should be provided to remove water from the
granular subbase.
We recommend drainage be included at the bottom of Aggregate Base (when used) at the
storm structures to aid in removing water that may enter this layer. Drainage could consist
of small diameter weep holes excavated around the perimeter of the storm structures.
The weep holes should be excavated at the elevation of the Aggregate Base and soil
interface. The excavation should be covered with Aggregate Base encompassed in Mirafi
140NL, or an approved equivalent, which will aid in reducing the amount of fines that
enter the storm system.
Pavement Maintenance
The pavement sections represent the minimum recommended thicknesses and, as such,
periodic upkeep should be anticipated. Preventive maintenance should be planned and
provided for through an on-going pavement management program. Maintenance activities
are intended to slow the rate of pavement deterioration and to preserve the pavement
investment. Pavement care consists of both localized (e.g., crack and joint sealing and
patching) and global maintenance (e.g., surface sealing). Additional engineering
consultation is recommended to determine the type and extent of a cost-effective
program. Even with periodic maintenance, some movement and related cracking may still
occur, and repairs may be required.
Pavement performance is affected by its surroundings. In addition to providing preventive
maintenance, the civil engineer should consider the following recommendations in the
design and layout of pavements:
■ Final grade adjacent to paved areas should slope down from the edges at a
minimum 2%.
■ Subgrade and pavement surfaces should have a minimum 2% slope to promote
proper surface drainage.
■ Install joint sealant and seal cracks immediately.
■ Seal all landscaped areas in or adjacent to pavements to reduce moisture migration
to subgrade soils.
■ Place compacted, low permeability backfill against the exterior side of curb and
gutter.
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General Comments
Our analysis and opinions are based upon our understanding of the project, the
geotechnical conditions in the area, and the data obtained from our site exploration.
Variations will occur between exploration point locations or due to the modifying effects
of construction or weather. The nature and extent of such variations may not become
evident until during or after construction. Terracon should be retained as the Geotechnical
Engineer, where noted in this report, to provide observation and testing services during
pertinent construction phases. If variations appear, we can provide further evaluation and
supplemental recommendations. If variations are noted in the absence of our observation
and testing services on-site, we should be immediately notified so that we can provide
evaluation and supplemental recommendations.
Our Scope of Services does not include either specifically or by implication any
environmental or biological (e.g., 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, other studies should
be undertaken.
Our services and any correspondence are intended for the sole benefit and exclusive use
of our client for specific application to the project discussed and are accomplished in
accordance with generally accepted geotechnical engineering practices with no third-party
beneficiaries intended. Any third-party access to services or correspondence is solely for
information purposes to support the services provided by Terracon to our client. Reliance
upon the services and any work product is limited to our client and is not intended for
third parties. Any use or reliance of the provided information by third parties is done solely
at their own risk. No warranties, either express or implied, are intended or made.
Site characteristics as provided are for design purposes and not to estimate excavation
cost. Any use of our report in that regard is done at the sole risk of the excavating cost
estimator as there may be variations on the site that are not apparent in the data that
could significantly affect excavation cost. Any parties charged with estimating excavation
costs should seek their own site characterization for specific purposes to obtain the specific
level of detail necessary for costing. Site safety and cost estimating including excavation
support and dewatering requirements/design are the responsibility of others. Construction
and site development have the potential to affect adjacent properties. Such impacts can
include damages due to vibration, modification of groundwater/surface water flow during
construction, foundation movement due to undermining or subsidence from excavation,
as well as noise or air quality concerns. Evaluation of these items on nearby properties
are commonly associated with contractor means and methods and are not addressed in
this report. The owner and contractor should consider a preconstruction/precondition
survey of surrounding development. If changes in the nature, design, or location of the
project are planned, our conclusions and recommendations shall not be considered valid
unless we review the changes and either verify or modify our conclusions in writing.
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Attachments
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Exploration and Testing Procedures
Field Exploration
Number of
Explorations Type of Exploration
Approximate
Exploration Depth
(feet)
Location
1 Soil Boring 51½ Proposed AST
1 Soil Boring 11½ Pavement Area
1 Geophysical Survey 100 Pavement/AST
Boring Layout and Elevations: Terracon personnel provided the boring layout using
handheld GPS equipment (estimated horizontal accuracy of about ±10 feet) and
referencing existing site features. Approximate ground surface elevations were obtained
by interpolation from ALTA/NSPS Title Survey prepared by BBA Land Surveying, dated
July 12, 2019. If elevations and a more precise boring layout are desired, we recommend
borings be surveyed.
Soil Boring Procedures: We advanced the borings with a track-mounted, rotary drill rig
using continuous flight, hollow stem augers or mud rotary. Four samples were obtained in
the upper 10 feet of each boring and at intervals of 5 feet thereafter. In the split-barrel
sampling procedure, a standard 2-inch outer diameter split-barrel sampling spoon was
driven into the ground by a 140-pound automatic hammer falling a distance of 30 inches.
The number of blows required to advance the sampling spoon the last 12 inches of a
normal 18-inch penetration is recorded as the Standard Penetration Test (SPT) resistance
value. The SPT resistance values, also referred to as N-values, are indicated on the boring
logs at the test depths. We observed and recorded groundwater levels during drilling and
sampling. For safety purposes, all borings were backfilled with bentonite chips after their
completion in accordance with Washington Department of Ecology requirements related
to completion of borings. Pavements were patched with concrete and cold-mix asphalt.
We also observed the boreholes while drilling and at the completion of drilling for the
presence of groundwater. The groundwater levels are shown on the attached boring logs.
The sampling depths, penetration distances, and other sampling information was recorded
on the field boring logs. The samples were placed in appropriate containers and taken to
our soil laboratory for testing and classification by a Geotechnical Engineer. Our
exploration team prepared field boring logs as part of the drilling operations. These field
logs included visual classifications of the materials observed during drilling and our
interpretation of the subsurface conditions between samples. Final boring logs were
prepared from the field logs. The final boring logs represent the Geotechnical Engineer's
Geotechnical Engineering Report
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interpretation of the field logs and include modifications based on observations and tests
of the samples in our laboratory.
Multichannel Analysis of Surface Waves (MASW) Profiling Survey: The Multichannel
Analysis of Surface Waves (MASW) technique was used to measure variations in surface
wave velocity as a function of frequency, and to model these data to determine subsurface
S-wave velocities (Vs). The seismic system consisted of 24 seismic sensors (geophones)
along two linear, 120-foot-long arrays intersecting perpendicularly. The survey was
comprised of two components: active and passive. The active component involves inducing
a seismic wave using the sledgehammer and measuring the seismic velocity along each
linear series of geophones. The passive component involves using ambient vibrational
noise as the energy source. The active and passive data was processed and modeled to
yield a 1-Dimensional (1D) line graph depicting shear wave velocity with depth and a
weighted average shear wave velocity for the top 100 ft (Vs100).
Limitations: The MASW technique works best in materials that produce high-amplitude
ground roll and significant dispersion between the body (P- and S-) waves and surface
waves. Consequently, low velocity surface materials such as sediments, or dam fill, tend
to provide higher quality MASW data than regions with shallow or exposed bedrock.
MASW data quality can be reduced by extraneous seismic energy sources such as wind,
traffic or nearby machinery. It is also subject to induced noise by power lines or other
field-generating sources. Furthermore, MASW data quality can be reduced when surveys
are conducted on asphalt or concrete surfaces which may reduce the frequency content of
the recorded waveform and limit the data quality of an MASW survey.
Laboratory Testing
The project engineer reviewed the field data and assigned laboratory tests. The laboratory
testing program included the following types of tests:
■ ASTM D2216 Standard Test Methods for Laboratory Determination of Water
(Moisture) Content of Soil and Rock by Mass
■ ASTM D4318 Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity
Index of Soils
■ ASTM D422 Standard Test Method for Particle-Size Analysis of Soils
■ ASTM D1140 Standard Test Methods for Determining the Amount of Material Finer
than 75-µm (No. 200) Sieve in Soils by Washing
■ ASTM D2974 Standard Test Methods for Determining the Water (Moisture) Content,
Ash Content, and Organic Material of Peat and Other Organic Soils
The laboratory testing program often included examination of soil samples by an engineer.
Based on the results of our field and laboratory programs, we described and classified the
soil samples in accordance with the Unified Soil Classification System.
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Photography Log
Photo 1: Hollow Stem Drilling performed
at boring location B-02.
Photo 2: Set up of North-South
Geophysical Transect.
Photo 3: Boring location, B-01, patched
with concrete and cold-mix asphalt after
drilling.
Photo 4: Boring location, B-02, patched
with concrete and cold-mix asphalt after
drilling.
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Photography Log
Photo 5: Ponding water observed to the northeast of boring location B-01.
Photo 6: Site photo looking east showing support truck at boring location B-01 and drill
rig at location B-02.
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials
Site Location and Exploration Plans
Contents:
Site Location Plan
Exploration Plan with site plan overlay
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials
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Site Location
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials
Note to Preparer: This is a large table with outside borders. Just click inside the table
above this text box, then paste your GIS Toolbox image.
When paragraph markers are turned on you may notice a line of hidden text above
and outside the table – please leave that alone. Limit editing to inside the table.
The line at the bottom about the general location is a separate table line. You can edit
it as desired, but try to keep to a single line of text to avoid reformatting the page.
Note to Preparer: This is a large table with outside borders. Just click inside the table
above this text box, then paste your GIS Toolbox image.
When paragraph markers are turned on you may notice a line of hidden text above
and outside the table – please leave that alone. Limit editing to inside the table.
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Exploration Plan with Site Plan Overlay
DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR CONSTRUCTION PURPOSES MAP PROVIDED BY MICROSOFT BING MAPS
Exploration and Laboratory Results
Contents:
GeoModel
Boring Logs (B-01 and B-02)
Atterberg Limits
Grain Size Distribution
Shear-Wave Velocity Profile
-25
-20
-15
-10
-5
0
5
10
15
20
25
30
EL
E
V
A
T
I
O
N
(
M
S
L
)
(
f
e
e
t
)
Layering shown on this figure has been developed by thegeotechnical engineer for purposes of modeling the subsurfaceconditions as required for the subsequent geotechnical engineeringfor this project.Numbers adjacent to soil column indicate depth below ground
surface.
NOTES:
B-01 B-02
Legend
This is not a cross section. This is intended to display the Geotechnical Model only. See individual logs for more detailed conditions.
GeoModel
17850 W Valley Hwy | Tukwila, WA
Terracon Project No. 81255059
Ryder Truck Rental LC-0549
21905 64th Ave W, Ste 100
Mountlake Terrace, WA
Second Water Observation
First Water Observation
Groundwater levels are temporal. The levels shown are representativeof the date and time of our exploration. Significant changes arepossible over time.Water levels shown are as measured during and/or after drilling. Insome cases, boring advancement methods mask the presence/absenceof groundwater. See individual logs for details.
Asphalt Silty Gravel withSand
Silt Silty Sand
Organic Silt Poorly-graded Sand
Silty Sand withGravel
Model Layer Layer Name General Description
1 Silty sand with gravel and silty gravel with sand, fine tocoarse grained, brownish gray, medium dense to dense
3 Sand with variable silt content, fine to medium grained,gray to dark gray, medium dense to dense, interbeds ofsilt observed
2 low plasticity silt with variable sand and gravel content and silty sand, variable organic content, gray to dark brown, very soft to medium stiff / very loose to medium dense
FILL
Lower Alluvium
Upper Alluvium
1
2
3
4
37
51.5
1
28.5
5.8 7
11.5
26.75
23
9
4
ASPHALT, ~3-inches thick
FILL - SILTY GRAVEL WITH SAND (GM), fineto coarse grained, subangular to angular,brownish gray, wet, dense
SILT WITH SAND (ML), low plasticity, gray todark gray, wet, soft to very soft
at ~5 feet: increase in gravel content, with
gravel
SILTY SAND (SM), fine grained, dark gray,wet, loose
ORGANIC SILT (OL), nonplastic, gray to darkbrown, wet, soft to medium stiff, wood debris
Boring Log No. B-01
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
15
20
25
Facilities | Environmental | Geotechnical | Materials
Approximate Elevation: 27 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
S-1: Rock fragments present within sample, blow counts may be overstatedS-2, S-4, and S-5: poor sample recovery due to soft soil conditions
71.2
15.8
22.3
40.9
34.9
147.5
16-28-19N=47
3-1-2N=3
1-0-2N=2
3-1-0N=1
1-0-0N=0
3-4-3N=7
1-2-2N=4
28-26-2
0.3
4.0
18.0
23.0
12
1
13
0
1
4
18
S-1
S-2
S-3
S-4
S-5
S-6
S-7
Advancement MethodMud rotaryNotes
Water Level ObservationsWater level measurement not attempted due tomud rotary method of boring advancement
See Exploration and Testing Procedures for a description of field and laboratory procedures used andadditional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevations were interpolated from a topographic site plan.
Samples obtained using a 2" O.D. split spoon sampler
Ryder Truck Rental LC-0549
Hammer TypeAuto. (ETR=90%)
17850 W Valley Hwy | Tukwila, WA
Terracon Project No. 81255059 Mountlake Terrace, WA
21905 64th Ave W, Ste 100
Drill RigD-70 Track Rig
DrillerHolocene
Logged byD. Nutter
Boring Started03-31-2025
Boring Completed03-31-2025
Abandonment MethodBoring backfilled with bentoniteSurface capped with approx. 2 feet of concrete andtopped with cold-mix asphalt
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Or
g
a
n
i
c
Co
n
t
e
n
t
(%
)
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
AtterbergLimits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 47.4432° Longitude: -122.2424°
Depth (Ft.)Re
c
o
v
e
r
y
(
I
n
.
)
Sa
m
p
l
e
I
D
1
2
-1
-6
-10
-21
-24.5
ORGANIC SILT (OL), nonplastic, gray to darkbrown, wet, soft to medium stiff, wood debris(continued)
SILTY SAND (SM), trace gravel, fine tomedium grained, dark gray, wet, mediumdense, with interbeds of SILT (ML)
SILT (ML), low plasticity, gray, wet, mediumstiff, trace organics
POORLY GRADED SAND (SP), fine to mediumgrained, dark gray, moist to wet, mediumdense to dense
at ~40 feet: silt content increasing with depth,becomes poorly graded sand with silt (SP-SM),iron oxidation observed
SILTY SAND (SM), fine grained, gray, wet,medium dense
at ~50 feet: frequent interbeds of SILT (ML)
Boring Terminated at 51.5 Feet
Boring Log No. B-01
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
30
35
40
45
50
Facilities | Environmental | Geotechnical | Materials
Approximate Elevation: 27 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
16.2
7.6
29.5
45.7
26.5
6-5-7N=12
0-0-5N=5
10-14-13N=27
15-16-17N=33
8-5-10N=15
41-28-13
28.0
33.0
37.0
48.0
51.5
10
17
16
16
17
S-8
S-9
S-10
S-11
S-12
Advancement MethodMud rotaryNotes
Water Level ObservationsWater level measurement not attempted due tomud rotary method of boring advancement
See Exploration and Testing Procedures for a description of field and laboratory procedures used andadditional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevations were interpolated from a topographic site plan.
Samples obtained using a 2" O.D. split spoon sampler
Ryder Truck Rental LC-0549
Hammer TypeAuto. (ETR=90%)
17850 W Valley Hwy | Tukwila, WA
Terracon Project No. 81255059 Mountlake Terrace, WA
21905 64th Ave W, Ste 100
Drill RigD-70 Track Rig
DrillerHolocene
Logged byD. Nutter
Boring Started03-31-2025
Boring Completed03-31-2025
Abandonment MethodBoring backfilled with bentoniteSurface capped with approx. 2 feet of concrete andtopped with cold-mix asphalt
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Or
g
a
n
i
c
Co
n
t
e
n
t
(%
)
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
AtterbergLimits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 47.4432° Longitude: -122.2424°
Depth (Ft.)Re
c
o
v
e
r
y
(
I
n
.
)
Sa
m
p
l
e
I
D
2
3
27.25
20.5
17.5
16
ASPHALT, ~3-inches thick
FILL - SILTY SAND WITH GRAVEL (SM), fineto coarse grained, brownish gray, moist, denseto medium dense
SILT (ML), low plasticity, gray, moist, verysoft, trace organics (wood debris)
SILTY SAND (SM), trace organics, finegrained, gray to dark gray, wet, very loose,twith interbeds of SILT (ML)
Boring Terminated at 11.5 Feet
Boring Log No. B-02
Wa
t
e
r
L
e
v
e
l
Ob
s
e
r
v
a
t
i
o
n
s
De
p
t
h
(
F
t
.
)
5
10
Facilities | Environmental | Geotechnical | Materials
Approximate Elevation: 27.5 (Ft.)
Gr
a
p
h
i
c
L
o
g
Mo
d
e
l
L
a
y
e
r
S-1 and S-2: Rock fragments present, blow counts may be overstated
25-24-21N=45
10-10-3N=13
0-0-1N=1
1-0-1N=1
42-31-11
0.3
7.0
10.0
11.5
14
10
15
12
S-1
S-2
S-3
S-4
Advancement Method4 1/4-inch ID Hollow Stem AugerNotes
Water Level Observations
Inferred from change in water content
Measured during drilling
See Exploration and Testing Procedures for a description of field and laboratory procedures used andadditional data (If any).
See Supporting Information for explanation of symbols and abbreviations.
Elevation Reference: Elevations were interpolated from a topographic site plan.
Samples obtained using a 2" O.D. split spoon sampler
Ryder Truck Rental LC-0549
Hammer TypeAuto. (ETR=90%)
17850 W Valley Hwy | Tukwila, WA
Terracon Project No. 81255059 Mountlake Terrace, WA
21905 64th Ave W, Ste 100
Drill RigD-70 Track Rig
DrillerHolocene
Logged byD. Nutter
Boring Started03-31-2025
Boring Completed03-31-2025
Abandonment MethodBoring backfilled with bentoniteSurface capped with approx. 3 feet of concrete andtopped with cold-mix asphalt
Sa
m
p
l
e
T
y
p
e
Pe
r
c
e
n
t
Fi
n
e
s
Or
g
a
n
i
c
Co
n
t
e
n
t
(%
)
Wa
t
e
r
Co
n
t
e
n
t
(
%
)
Fi
e
l
d
T
e
s
t
Re
s
u
l
t
s
AtterbergLimits
LL-PL-PI
See Exploration PlanLocation:
Latitude: 47.4431° Longitude: -122.2425°
Depth (Ft.)Re
c
o
v
e
r
y
(
I
n
.
)
Sa
m
p
l
e
I
D
1
2
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0.0010.010.1110100
16 2044 100
U.S. Sieve Numbers
SandGravel
Grain Size (mm)
coarse fine coarse finemedium
Silt or ClayCobbles
Pe
r
c
e
n
t
C
o
a
r
s
e
r
b
y
W
e
i
g
h
t
Pe
r
c
e
n
t
F
i
n
e
r
b
y
W
e
i
g
h
t
100
90
80
70
60
50
40
30
20
10
0632 10 14 506 2001.5 83/4
1/23/8 30 403 601 140
HydrometerU.S. Sieve Opening in Inches
Grain Size Distribution
ASTM D422 / ASTM C136 / AASHTO T27
Facilities | Environmental | Geotechnical | Materials
LL PL PI Cc CuDescription
SILT with sand
silty SAND
silty SAND
poorly graded SAND with silt 3.43
%Clay%Sand%Gravel
0.5 91.90.0
D10
0.107
D30
0.21
0.075
0.075
0.075
9.5
%Fines %Silt
71.2
15.8
16.2
7.6
28
1.12
226
%CobblesD60
0.368
D100
Boring ID Depth (Ft)
7.5 - 9
20 - 21.5
30 - 31.5
40 - 41.5
B-01
B-01
B-01
B-01
7.5 - 9
20 - 21.5
30 - 31.5
40 - 41.5
Depth (Ft)Boring ID
B-01
B-01
B-01
B-01
21905 64th Ave W, Ste 100
Mountlake Terrace, WATerracon Project No. 81255059
17850 W Valley Hwy | Tukwila, WA
Ryder Truck Rental LC-0549
USCS
ML
SM
SM
SP-SM
0
10
20
30
40
50
60
0 10 20 30 40 50 60 70 80 90 100 110
"A" L
i
n
e
ASTM D4318
CH
o
r
O
H
CL
o
r
O
L
ML or OL
MH or OH
2
13
11
71.2 ML
ML
ML
26
28
31
2
13
11
71.2 ML
ML
ML
26
28
31
28
41
42
SILT with sand
SILT
SILT
Atterberg Limit Results
"U"
L
i
n
e
Liquid Limit
LL PL PI Fines USCS DescriptionFines
Pl
a
s
t
i
c
i
t
y
I
n
d
e
x
CL - ML
16
4
7
Facilities | Environmental | Geotechnical | Materials
7.5 - 9
35 - 36.5
7.5 - 9
B-01
B-01
B-02
Boring ID Depth (Ft)
21905 64th Ave W, Ste 100
Mountlake Terrace, WATerracon Project No. 81255059
17850 W Valley Hwy | Tukwila, WA
Ryder Truck Rental LC-0549
Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
0 200 400 600 800 1000 1200
De
p
t
h
B
e
l
o
w
G
r
o
u
n
d
S
u
r
f
a
c
e
,
f
t
Shear-Wave Velocity, ft/s
Vs from Multichannel Analysis of SurfaceWaves
Vs100 = 590 ft/sec
ASCE 7-16 Site Class E or FASCE 7-22 Site Class DE
Shear Wave Velocity Profile
Supporting Information
Contents:
Liquefaction Analysis Report (2 pages)
Historic Boring Logs (B-01 and B02; 2019)
General Notes
Unified Soil Classification System
Note: All attachments are one page unless noted above.
SPT BASED LIQUEFACTION ANALYSIS REPORT
:: Input parameters and analysis properties ::
Analysis method:
Fines correction method:
Sampling method:
Borehole diameter:
Rod length:
Hammer energy ratio:
NCEER 1998
NCEER 1998
Sampler wo liners
65mm to 115mm
3.30 ft
1.50
G.W.T. (in-situ):
G.W.T. (earthq.):
Earthquake magnitude Mw:
Peak ground acceleration:
Eq. external load:
Project title : Ryder Truck Rental
Location : Tukwila, WA
Terracon Consultants, Inc.
K.Morrow
SPT Name: B-01
6.00 ft
6.00 ft
7.11
0.68 g
0.00 tsf
Raw SPT Data
SPT Count (blows/ft)
50403020100
De
p
t
h
(
f
t
)
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
Raw SPT Data
Insitu
CSR - CRR Plot
CSR - CRR
10.80.60.40.20
De
p
t
h
(
f
t
)
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
CSR - CRR Plot
During earthq.
FS Plot
Factor of Safety
21.510.50
De
p
t
h
(
f
t
)
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
FS Plot
During earthq.
LPI
Liquefaction potential
40200
De
p
t
h
(
f
t
)
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
LPI
During earthq.
CRR 7.50 clean sand curve
Corrected Blow Count N1(60),cs
50454035302520151050
Cy
c
l
i
c
S
t
r
e
s
s
R
a
t
i
o
*
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
CRR 7.50 clean sand curve
Liquefaction
No Liquefaction
F.S. color scheme
Almost certain it will liquefy
Very likely to liquefy
Liquefaction and no liq. are equally likely
Unlike to liquefy
Almost certain it will not liquefy
LPI color scheme
Very high risk
High risk
Low risk
Project File:
Page: 1LiqSVs 2.2.1.8 - SPT & Vs Liquefaction Assessment Software
This software is registered to: Software Compliance
Raw SPT Data
SPT Count (blows/ft)
50403020100
De
p
t
h
(
f
t
)
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
Raw SPT Data
Insitu
CSR - CRR Plot
CSR - CRR
10.80.60.40.20
De
p
t
h
(
f
t
)
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
CSR - CRR Plot
During earthq.
FS Plot
Factor of Safety
21.510.50
De
p
t
h
(
f
t
)
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
FS Plot
During earthq.
Vertical Liq. Settlements
Cuml. Settlement (in)
1050
De
p
t
h
(
f
t
)
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
Vertical Liq. Settlements
During earthq.
Lateral Liq. Displacements
Cuml. Displacement (ft)
0
De
p
t
h
(
f
t
)
50
48
46
44
42
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
Lateral Liq. Displacements
During earthq.
:: Overall Liquefaction Assessment Analysis Plots ::
Project File:
Page: 2LiqSVs 2.2.1.8 - SPT & Vs Liquefaction Assessment Software
StandardPenetration
Test
Facilities | Environmental | Geotechnical | Materials
less than 0.25
0.50 to 1.00
1.00 to 2.00
> 4.00
0.25 to 0.50
2.00 to 4.00
UnconfinedCompressiveStrength Qu (tsf)
Ryder Truck Rental LC-0549
17850 W Valley Hwy | Tukwila, WA
Terracon Project No. 81255059 21905 64th Ave W, Ste 100
Mountlake Terrace, WA
N
(HP)
(T)
(DCP)
UC
(PID)
(OVA)
Standard Penetration TestResistance (Blows/Ft.)
Hand Penetrometer
Torvane
Dynamic Cone Penetrometer
Unconfined CompressiveStrength
Photo-Ionization Detector
Organic Vapor Analyzer
Water Level After aSpecified Period of Time
Water Level Aftera Specified Period of Time
Cave InEncountered
Water Level Field Tests
Water InitiallyEncountered
Sampling
Water levels indicated on the soil boring logs are the
levels measured in the borehole at the times
indicated. Groundwater level variations will occur over
time. In low permeability soils, accurate
determination of groundwater levels is not possible
with short term water level observations.
General Notes
Location And Elevation Notes
Exploration point locations as shown on the Exploration Plan and as noted on the soil boring logs in the form of Latitude and Longitude are
approximate. See Exploration and Testing Procedures in the report for the methods used to locate the exploration points for this project. Surface
elevation data annotated with +/- indicates that no actual topographical survey was conducted to confirm the surface elevation. Instead, the surface
elevation was approximately determined from topographic maps of the area.
Soil classification as noted on the soil boring logs is based Unified Soil Classification System. Where sufficient laboratory data exist to classify the
soils consistent with ASTM D2487 "Classification of Soils for Engineering Purposes" this procedure is used. ASTM D2488 "Description and
Identification of Soils (Visual-Manual Procedure)" is also used to classify the soils, particularly where insufficient laboratory data exist to classify the
soils in accordance with ASTM D2487. In addition to USCS classification, coarse grained soils are classified on the basis of their in-place relative
density, and fine-grained soils are classified on the basis of their consistency. See "Strength Terms" table below for details. The ASTM standards
noted above are for reference to methodology in general. In some cases, variations to methods are applied as a result of local practice or
professional judgment.
Exploration/field results and/or laboratory test data contained within this document are intended for application to the project as described in this
document. Use of such exploration/field results and/or laboratory test data should not be used independently of this document.
Relevance of Exploration and Laboratory Test Results
Descriptive Soil Classification
Strength Terms
4 - 8
0 - 1
> 30
4 - 9
30 - 50
> 50
15 - 46
47 - 79
> 80 Very Stiff
Hard
< 3
3 - 5
11 - 18
19 - 36
2 - 4
8 - 15
15 - 30
(50% or more passing the No. 200 sieve.)
Consistency determined by laboratory shear strength testing, field visual-manualprocedures or standard penetration resistance
Relative Density of Coarse-Grained Soils
Very Loose
Loose
Medium Dense
Dense
Very Dense
10 - 29
0 - 3 0 - 5
6 - 14
Very Soft
Soft
Medium Stiff
Stiff
6 - 10
Consistency of Fine-Grained Soils
(More than 50% retained on No. 200 sieve.)Density determined by Standard Penetration Resistance
Ring Sampler(Blows/Ft.)Relative Density Consistency Standard Penetrationor N-Value(Blows/Ft.)
Standard Penetrationor N-Value(Blows/Ft.)
RingSampler(Blows/Ft.)
> 37
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Geotechnical Engineering Report
Ryder LC-0549 Fuel System | Tukwila, WA
May 23, 2025 | Terracon Project No. 81255059
Facilities | Environmental | Geotechnical | Materials
Unified Soil Classification System
Criteria for Assigning Group Symbols and Group Names Using
Laboratory Tests A
Soil Classification
Group Symbol Group Name B
Coarse-Grained Soils: More than 50% retained
on No. 200 sieve
Gravels: More than 50% of
coarse fraction retained on No. 4
sieve
Clean Gravels: Less than 5% fines C
Cu≥4 and 1≤Cc≤3 E GW Well-graded gravel F
Cu<4 and/or [Cc<1 or Cc>3.0] E GP Poorly graded gravel F
Gravels with Fines:
More than 12% fines C
Fines classify as ML or MH GM Silty gravel F, G, H
Fines classify as CL or CH GC Clayey gravel F, G, H
Sands: 50% or more of
coarse fraction passes No. 4 sieve
Clean Sands: Less than 5% fines D
Cu≥6 and 1≤Cc≤3 E SW Well-graded sand I
Cu<6 and/or [Cc<1 or Cc>3.0] E SP Poorly graded sand I
Sands with Fines:
More than 12% fines D
Fines classify as ML or MH SM Silty sand G, H, I
Fines classify as CL or CH SC Clayey sand G, H, I
Fine-Grained Soils: 50% or more passes the
No. 200 sieve
Silts and Clays:
Liquid limit less than 50
Inorganic: PI > 7 and plots above “A” line J CL Lean clay K, L, M
PI < 4 or plots below “A” line J ML Silt K, L, M
Organic: 𝐿𝐿 𝑛𝑣𝑑𝑛 𝑑𝑟𝑖𝑑𝑑
𝐿𝐿 𝑛𝑛𝑡 𝑑𝑟𝑖𝑑𝑑<0.75 OL Organic clay K, L, M, N
Organic silt K, L, M, O
Silts and Clays:
Liquid limit 50 or more
Inorganic: PI plots on or above “A” line CH Fat clay K, L, M
PI plots below “A” line MH Elastic silt K, L, M
Organic: 𝐿𝐿 𝑛𝑣𝑑𝑛 𝑑𝑟𝑖𝑑𝑑
𝐿𝐿 𝑛𝑛𝑡 𝑑𝑟𝑖𝑑𝑑<0.75 OH Organic clay K, L, M, P
Organic silt K, L, M, Q
Highly organic soils: Primarily organic matter, dark in color, and organic odor PT Peat
A Based on the material passing the 3-inch (75-mm) sieve. B If field sample contained cobbles or boulders, or both, add “with
cobbles or boulders, or both” to group name. C Gravels with 5 to 12% fines require dual symbols: GW-GM well-
graded gravel with silt, GW-GC well-graded gravel with clay, GP-GM poorly graded gravel with silt, GP-GC poorly graded gravel with clay.
D Sands with 5 to 12% fines require dual symbols: SW-SM well-graded sand with silt, SW-SC well-graded sand with clay, SP-SM
poorly graded sand with silt, SP-SC poorly graded sand with clay.
E Cu = D60/D10 Cc =
F If soil contains ≥ 15% sand, add “with sand” to group name.
G If fines classify as CL-ML, use dual symbol GC-GM, or SC-SM.
H If fines are organic, add “with organic fines” to group name. I If soil contains ≥ 15% gravel, add “with gravel” to group name.
J If Atterberg limits plot in shaded area, soil is a CL-ML, silty clay. K If soil contains 15 to 29% plus No. 200, add “with sand” or
“with gravel,” whichever is predominant. L If soil contains ≥ 30% plus No. 200 predominantly sand, add
“sandy” to group name. M If soil contains ≥ 30% plus No. 200, predominantly gravel, add
“gravelly” to group name. N PI ≥ 4 and plots on or above “A” line.
O PI < 4 or plots below “A” line. P PI plots on or above “A” line.
Q PI plots below “A” line.
6010
2
30
DxD
)(D