HomeMy WebLinkAboutRS_GeotechnicalMemo_251008_v1Memorandum
2101 4th Avenue, Suite 950, Seattle, Washington 98121, Telephone: 206.728.2674 www.geoengineers.com
To: Puget Sound Energy
From: Timothy D. Bailey, PE
Date: October 7, 2025
File: 9186-184-00, Task 2032
Subject: Geotechnical Design Memorandum –
Pole and Fence Foundations
SWARR Station – Security Perimeter
Maintenance Project
2100 Benson Drive South, Renton, Washington
Introduction
This design memorandum presents the results of GeoEngineers, Inc.’s (GeoEngineers) geotechnical
engineering services associated with the pole and fence foundations associated with the proposed security
perimeter maintenance project at the existing PSE Renton SWARR station located in Renton, Washington
(King County Parcel No. 2023059071). The project site is shown in relation to existing features in the
Vicinity Map, Figure 1 and the Site Plan, Figure 2.
We understand that Puget Sound Energy (PSE) is planning to replace the existing 6-foot-high chain-link
fence with a new 8-foot-high Tier 2 metal mesh fence that includes intrusion detection and is also planning
to install additional security cameras. However, it is anticipated that the new fence may be 2 to 4 feet taller
in some areas to accommodate the existing terrain and top of fence design elevation. The replacement
fence alignment will generally follow the existing fence alignment with some alignment shifts within the
existing fence perimeter to avoid tree removal.
This design memorandum incorporates PSE review comments and supersedes the previous version dated
November 5, 2024.
Scope of Services
Our services were completed in accordance with our proposal dated August 30, 2024 and included:
■Completing geotechnical explorations using hand tools and hand operated instruments at the site.
■Completing geotechnical laboratory testing on selected soil samples from the explorations.
■Providing geotechnical conclusions and recommendations for the proposed fence replacement
foundations and camera pole foundations, and
■Preparing this memorandum.
10/7/2025
Memorandum to Puget Sound Energy
October 7, 2025
Page 2
Geotechnical Field Exploration and Laboratory Testing
FIELD EXPLORATIONS
Subsurface conditions at the site were evaluated on September 27, 2024, by completing nine hand auger
explorations (HA-1 through HA-9) to depths ranging from approximately 0.5 to 2.5 feet below the ground
surface (bgs). The explorations included manual samples and direct cone penetrometer (DCP) testing to
evaluate soil density. A description of the field exploration program and summary exploration logs are
presented in Attachment A. The exploration locations are shown in Figure 2.
GEOTECHNICAL LABORATORY TESTING
Soil samples were obtained during the hand auger explorations and taken to GeoEngineers’ Redmond
laboratory for further evaluation. Selected samples were tested for the determination of grain-size
distribution (sieve analysis). A description of the laboratory testing and the test results are presented in
Attachment A or on the exploration logs.
Site Conditions
GEOLOGY
We reviewed the geologic map of the Renton quadrangle (Mullineaux et al., 1965). Surficial soils in the
project vicinity are mapped on the geologic map as ground moraine deposits consisting of mostly ablation
till over lodgment till (Qgt). Till generally consists of a medium dense to very dense unsorted mixture of clay,
silt, sand, gravel, cobbles and boulders. We observed a large glacial erratic boulder on site adjacent to the
access road, which is consistent with geologic mapping.
SURFACE CONDITIONS
The project site is approximately 16.7 acres in size and is developed with below-ground propane storage
tanks, process equipment that produces a mixture of propane and air, and a one-story building that houses
process equipment and control operations. The site is accessed from a paved road coming off South
Benson Drive to the west and is surrounded by a chain-link fence. The fenced site is bordered by South
Benson Drive to the west and by undeveloped forested areas to the north, south and east. The site is
located in a small valley, with the topography rising to the east and west. Rolling Hills Creek flows south-to-
north below the site in a culvert, with the culvert inlet structure located at the south end of the site, just
south of the access road.
SUBSURFACE CONDITIONS
The driveway ramp supporting the main paved entry is anticipated to consist of fill. Additionally, there are
unknown quantities and depths of fill supporting the main building pad and aboveground utility
infrastructure, as well as fill placed on top of the underground storage tanks (USTs).
Based on our explorations, subsurface conditions consist of fill and glacial till extending to the depths
explored. The fill is likely regraded glacial till and both the fill and glacial till consist of sand with variable
silt and gravel content.
Memorandum to Puget Sound Energy
October 7, 2025
Page 3
Groundwater was not observed in our explorations. During our September 27, 2024 site visit, we measured
groundwater levels in three existing monitoring wells at the site (well locations are noted in Figure 2).
The monitoring wells did not have Washington State Department of Ecology well tags, so we were unable
to locate the original boring logs. We identified the wells and associated depth to groundwater as follows:
■ MW-1 (south end of site, adjacent to access road) – groundwater at a depth of 19 feet.
■ MW-2 (north end of site, between tanks and access road) – groundwater at a depth of 16 feet.
■ MW-3 (southwest of the building) – groundwater at a depth of 10 feet.
GEOLOGICALLY HAZARDOUS AREAS
Geologically hazardous areas are discussed separately in another report being prepared by GeoEngineers.
Conclusions and Recommendations
FENCE POST AND CAMERA FOUNDATIONS
The new fence post foundations are anticipated to be 24 inches in diameter and 3 feet deep. The camera
pole foundations are anticipated to be 3 feet in diameter and 7 feet deep for 15-foot-high camera poles or
8.5 feet deep for 25-foot-high camera poles. The soil conditions for these foundations are anticipated to
consist of fill overlying glacial till.
If lateral bearing pressures are needed for design of post or pole foundations, an allowable lateral bearing
pressure of 1500 pounds per square foot (psf) can be used as a conservative value, which is consistent
with loose (blowcount, N = 10) soil in Table 17-2 in the Washington State Department of Transportation
Geotechnical Design Manual.
If LPile design parameters are needed for design of these foundations, the parameters presented in Table 1
below can be used. The soil parameters were developed based on our field explorations and extrapolation
of anticipated conditions below the depths explored, based on geologic mapping that shows glacial till and
the documented refusal conditions encountered in the hand auger explorations.
TABLE 1. 2021 LPILE PARAMETERS
SOIL PARAMETER FILL AND GLACIAL TILL
Depth below existing ground surface (feet) 0-10
Soil Type (p-y curve model) Sand (Reese)
Effective Unit Weight (pcf) 125
Friction Angle (degrees) 32
p-y Modulus, k (pci) 50
Notes:
pcf = pounds per cubic foot; pci = pounds per cubic inch
Memorandum to Puget Sound Energy
October 7, 2025
Page 4
Limitations
We have prepared this report for the exclusive use of PSE and their authorized agents for the proposed
SWARR Station – Security Perimeter Maintenance project in Renton, Washington.
Within the limitations of scope, schedule and budget, our services have been executed in accordance with
generally accepted practices in the field of geotechnical engineering in this area at the time this report was
prepared. No warranty or other conditions, express or implied, should be understood.
Please refer to Attachment B, Report Limitations and Guidelines for Use, for additional information
pertaining to the use of this report.
References
Mullineaux, D.R., 1965, “Geologic map of the Renton quadrangle, King County, Washington,” U.S.
Geological Survey, Geologic Quadrangle Map GQ-405, 1:24,000.
Washington State Department of Transportation, February 2022, Geotechnical Design Manual M 46-03.16.
U.S. Geological Survey, MapView, accessed October 1, 2024 from web site:
https://ngmdb.usgs.gov/mapview/?center=-97,39.6&zoom=4.
GDT:TDB:mce
Attachments:
Figure 1. Vicinity Map
Figure 2. Site Plan
Attachment A. Field Explorations and Laboratory Testing
Figure A-1. Key to Exploration Logs
Figures A-2 through A-10. Logs of Explorations
Figure A-11. Sieve Analysis Results
Attachment B. Report Limitations and Guidelines for Use
Disclaimer: Any electronic form, facsimile or hard copy of the original document (email, text, table and/or figure), if provided, and any attachments are only a copy of the original document. The original document is stored by GeoEngineers, Inc. and will serve as the official document of record.
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Coordinate System: NAD 1983 UTM Zone 10N
Disclaimer: This figure was created for a specific purpose and project. Any use of this figurefor any other project or purpose shall be at the user's sole risk and without liability to GeoEngineers.
The locations of features shown may be approximate. GeoEngineers makes no warranty orrepresentation as to the accuracy, completeness, or suitability of the figure, or data containedtherein. The file containing this figure is a copy of a master document, the original of which isretained by GeoEngineers and is the official document of record.
SWARR
Security Perimeter Maintenance ProjectRenton, Washington
HA-4
MW-2
HA-5HA-6
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Site Plan
SWARRSecurity Perimeter Maintenance ProjectRenton, Washington
Figure 2
0 120
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Legend
Hand Auger Exploration Completed by GeoEngineers
Unknown Monitoring Well
Rebuild Fence - Approximate Location (2,133.3 feet)
Existing Fence (2,976.8 feet)
P:\9\9186184\GIS\9186184_2024_Q4\9186184_2024_Q4.aprx\918618400_F02_SitePlan_Tsk2032 Date Exported: 10/08/25 by maugust
Source(s):• Drawing updated with proposed fence alignment 10/3/24.• Roads, 2023 aerial, contours and parcel boundaries from King County GIS. http://www.kingcounty.gov/services/gis.aspx
Coordinate System: NAD 1983 HARN StatePlane Washington North FIPS 4601 Feet
Disclaimer: This figure was created for a specific purpose and project. Any use of this figurefor any other project or purpose shall be at the user's sole risk and without liability to GeoEngineers.
The locations of features shown may be approximate. GeoEngineers makes no warranty or
representation as to the accuracy, completeness, or suitability of the figure, or data containedtherein. The file containing this figure is a copy of a master document, the original of which isretained by GeoEngineers and is the official document of record.
Attachment A
Field Explorations and Laboratory Testing
Memorandum to Puget Sound Energy
October 7, 2025
Page A-1
Attachment A
Field Explorations and Laboratory Testing
FIELD EXPLORATIONS
Subsurface conditions at the site were evaluated on September 27, 2024, by completing nine hand auger
explorations (HA-1 through HA-9). The approximate exploration locations are shown in the Site Plan,
Figure 2. Exploration locations were measured from existing site features.
Hand Auger Explorations
Hand auger explorations were completed by excavating using a post-hole digger and hand auger, with
samples collected manually. The density of the soils encountered in the explorations were evaluated using
a direct cone penetrometer (DCP), which uses a 15-pound hammer free-falling 20 inches to penetrate a
1.5-inch-diameter, 45-degree cone to a depth of 1¾ inch into the bottom of the hole. DCP blowcounts can
be correlated to standard penetration test (SPT) blowcounts. Both DCP and estimated SPT blow counts are
shown on the exploration logs at the evaluation depths.
Soils encountered in the explorations were visually classified in accordance with the classification system
described in Figure A-1. A key to the exploration log symbols is also presented in Figure A-1. The logs of the
explorations are presented in Figures A-2 through A-10. The logs reflect our interpretation of the field
conditions and the results of laboratory testing and evaluation of samples. They also indicate the depths at
which the soil types or their characteristics change, although the change might actually be gradual.
The ground surface elevations shown on the logs were estimated from GIS data.
LABORATORY TESTING
Soil samples obtained from the field explorations were transported to our laboratory and examined to
confirm or modify field classifications, as well as to evaluate index properties of the soil samples.
Representative samples were selected for laboratory testing consisting of the determination of sieve
analysis (gradation).
Sieve Analyses
Sieve analyses were performed on selected samples in accordance with ASTM International (ASTM) D 6913
to determine the sample grain-size distribution. The wet sieve analysis method was used to determine the
percentage of soil greater than the U.S. No. 200 mesh sieve. The results of the sieve analyses were plotted,
and samples were classified in accordance with the Unified Soil Classification System (USCS). Results are
presented in Figure A-11.
Measured groundwater level in exploration,well, or piezometer
Measured free product in well or piezometer
Distinct contact between soil strata
Approximate contact between soil strata
Contact between geologic units
SYMBOLS TYPICAL
DESCRIPTIONS
GW
GP
SW
SP
SM
FINEGRAINED
SOILS
SILTS ANDCLAYS
NOTE: Multiple symbols are used to indicate borderline or dual soil classifications
MORE THAN 50%RETAINED ONNO. 200 SIEVE
MORE THAN 50%PASSINGNO. 200 SIEVE
GRAVEL
ANDGRAVELLYSOILS
SC
LIQUID LIMITLESS THAN 50
(APPRECIABLE AMOUNTOF FINES)
(APPRECIABLE AMOUNTOF FINES)
COARSEGRAINEDSOILS
MAJOR DIVISIONS GRAPH LETTER
GM
GC
ML
CL
OL
SILTS AND
CLAYS
SANDS WITHFINES
SANDANDSANDY
SOILS
MH
CH
OH
PT
(LITTLE OR NO FINES)
CLEAN SANDS
GRAVELS WITHFINES
CLEAN GRAVELS
(LITTLE OR NO FINES)
WELL-GRADED GRAVELS, GRAVEL -SAND MIXTURES
CLAYEY GRAVELS, GRAVEL - SAND -CLAY MIXTURES
WELL-GRADED SANDS, GRAVELLYSANDS
POORLY-GRADED SANDS, GRAVELLYSAND
SILTY SANDS, SAND - SILT MIXTURES
CLAYEY SANDS, SAND - CLAYMIXTURES
INORGANIC SILTS, ROCK FLOUR,CLAYEY SILTS WITH SLIGHTPLASTICITY
INORGANIC CLAYS OF LOW TOMEDIUM PLASTICITY, GRAVELLYCLAYS, SANDY CLAYS, SILTY CLAYS,LEAN CLAYS
ORGANIC SILTS AND ORGANIC SILTYCLAYS OF LOW PLASTICITY
INORGANIC SILTS, MICACEOUS ORDIATOMACEOUS SILTY SOILS
INORGANIC CLAYS OF HIGHPLASTICITY
ORGANIC CLAYS AND SILTS OFMEDIUM TO HIGH PLASTICITY
PEAT, HUMUS, SWAMP SOILS WITHHIGH ORGANIC CONTENTSHIGHLY ORGANIC SOILS
SOIL CLASSIFICATION CHART
MORE THAN 50%OF COARSEFRACTION RETAINEDON NO. 4 SIEVE
MORE THAN 50%OF COARSEFRACTION PASSINGON NO. 4 SIEVE
SILTY GRAVELS, GRAVEL - SAND -SILT MIXTURES
POORLY-GRADED GRAVELS,GRAVEL - SAND MIXTURES
LIQUID LIMIT GREATERTHAN 50
Contact between soil of the same geologicunit
Material Description Contact
Graphic Log Contact
NOTE: The reader must refer to the discussion in the report text and the logs of explorations for a proper understanding of subsurface conditions.Descriptions on the logs apply only at the specific exploration locations and at the time the explorations were made; they are not warranted to berepresentative of subsurface conditions at other locations or times.
Groundwater Contact
Blowcount is recorded for driven samplers as the number ofblows required to advance sampler 12 inches (or distance noted).See exploration log for hammer weight and drop.
"P" indicates sampler pushed using the weight of the drill rig.
"WOH" indicates sampler pushed using the weight of thehammer.
Key to Exploration Logs
Figure A-1
ADDITIONAL MATERIAL SYMBOLS
SYMBOLS
Asphalt Concrete
Cement Concrete
Crushed Rock/Quarry Spalls
Topsoil
GRAPH LETTER
AC
CC
SOD Sod/Forest Duff
CR
DESCRIPTIONS
TYPICAL
TS
No Visible SheenSlight SheenModerate SheenHeavy Sheen
Laboratory / Field Tests
%F%GALCACPCSDDDSHAMCMDMohsOCPMPIPLPPSATXUCUUVS
Sheen Classification
NSSSMSHS
Percent finesPercent gravelAtterberg limitsChemical analysisLaboratory compaction testConsolidation testDry densityDirect shearHydrometer analysisMoisture contentMoisture content and dry densityMohs hardness scaleOrganic contentPermeability or hydraulic conductivityPlasticity indexPoint load testPocket penetrometerSieve analysisTriaxial compressionUnconfined compressionUnconsolidated undrained triaxial compressionVane shear
Continuous Coring
Bulk or grab
Direct-Push
Piston
Shelby tube
Standard Penetration Test (SPT)
Sampler Symbol Descriptions
Modified California Sampler (6-inch sleeve) or Dames & Moore
Rev. 03/2024
Brown silty sand (medium dense, moist)
Boring terminated at approximately 1.2 feet below ground surface(bgs) due to hand auger refusal
SM
1
Dynamic Cone Penetrometer (DCP) (15-poundhammer/20-inch drop) blowcount converted to anequivalent standard penetration test (SPT) blowcountbased on ASTM STP 399
DCP = 24 (SPT >20)
Notes: See Figure A-1 for explanation of symbols.The depths on the hand-augered boring logs are based on an average of measurements across the hand-auger and should be considered accurate to ½ foot.Coordinates Data Source: Horizontal approximated based on . Vertical approximated based on .
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Sheet 1 of 1Project Number:
Project Location:
Project:
9186-184-00 Task 2032
Log of Hand Auger HA-1
Figure A-2
SWARR Station - Security Perimeter Maintenance Project
Renton, Washington
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DateExcavated
Surface Elevation (ft)Vertical Datum Coordinate SystemHorizontal DatumLatitudeLongitude
TotalDepth (ft)9/27/2024 1.25
181NAVD88 47.461129-122.205816 Decimal DegreesWGS84
JSP/JX
Checked By TB
Groundwater not observed
Caving not observedEquipment Hand Auger/DCP
Logged By Excavator GeoEngineers, Inc.
Brown silty sand (medium dense, moist)
Boring terminated at approximately 2.5 feet bgs due to hand augerrefusal
SM
1SA 5
DCP (15-pound hammer/20-inch drop) blowcountconverted to an equivalent SPT blowcount based onASTM STP 399
DCP = 21 (SPT >15)34
Notes: See Figure A-1 for explanation of symbols.The depths on the hand-augered boring logs are based on an average of measurements across the hand-auger and should be considered accurate to ½ foot.Coordinates Data Source: Horizontal approximated based on . Vertical approximated based on .
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Sheet 1 of 1Project Number:
Project Location:
Project:
9186-184-00 Task 2032
Log of Hand Auger HA-2
Figure A-3
SWARR Station - Security Perimeter Maintenance Project
Renton, Washington
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DateExcavated
Surface Elevation (ft)Vertical Datum Coordinate SystemHorizontal DatumLatitudeLongitude
TotalDepth (ft)9/27/2024 2.5
175NAVD88 47.461188-122.205435 Decimal DegreesWGS84
JSP/JX
Checked By TB
Groundwater not observed
Caving not observedEquipment Hand Auger/DCP
Logged By Excavator GeoEngineers, Inc.
Brown silty sand with gravel (medium dense, moist)
Boring terminated at approximately 2 feet bgs due to hand augerrefusal
SM
1
DCP (15-pound hammer/20-inch drop) blowcountconverted to an equivalent SPT blowcount based onASTM STP 399
DCP = 19 (SPT >15)
Soil probe rod penetrated approximately ½-inch
Notes: See Figure A-1 for explanation of symbols.The depths on the hand-augered boring logs are based on an average of measurements across the hand-auger and should be considered accurate to ½ foot.Coordinates Data Source: Horizontal approximated based on . Vertical approximated based on .
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1
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G
E
O
T
E
C
_
%
F
Sheet 1 of 1Project Number:
Project Location:
Project:
9186-184-00 Task 2032
Log of Hand Auger HA-3
Figure A-4
SWARR Station - Security Perimeter Maintenance Project
Renton, Washington
Ele
v
a
t
i
o
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(
f
e
e
t
)
162
161
De
p
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h
(
f
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)
1
2
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S
a
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Gr
a
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SAMPLE
MATERIAL
DESCRIPTION
Gr
o
u
p
Cla
s
s
i
f
i
c
a
t
i
o
n
Sa
m
p
l
e
N
a
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Te
s
t
i
n
g
Mo
i
s
t
u
r
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Co
n
t
e
n
t
(
%
)
REMARKS
Fin
e
s
Co
n
t
e
n
t
(
%
)
DateExcavated
Surface Elevation (ft)Vertical Datum Coordinate SystemHorizontal DatumLatitudeLongitude
TotalDepth (ft)9/27/2024 2
163NAVD88 47.462043-122.205436 Decimal DegreesWGS84
JSP/JX
Checked By TB
Groundwater not observed
Caving not observedEquipment Hand Auger/DCP
Logged By Excavator GeoEngineers, Inc.
Forest duff
Dark brown poorly-graded fine to medium sand with silt and occasionalgravel and cobbles (medium dense, moist)
Brown well-graded gravel with silt and sand (medium dense, moist)
Boring terminated at approximately 2 feet bgs due to hand augerrefusal
DUFF
SP-SM
GW-GM
1SA 6
DCP (15-pound hammer/20-inch drop) blowcountconverted to an equivalent SPT blowcount based onASTM STP 399
DCP = 36 (SPT >20)Soil probe rod penetrated approximately ½-inch
Probe depth of ½-inch
9
Notes: See Figure A-1 for explanation of symbols.The depths on the hand-augered boring logs are based on an average of measurements across the hand-auger and should be considered accurate to ½ foot.Coordinates Data Source: Horizontal approximated based on . Vertical approximated based on .
Da
t
e
:
1
0
/
3
1
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2
4
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a
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:
P
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9
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9
1
8
6
1
8
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0
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_
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:
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.
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8
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_
1
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G
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O
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E
C
_
%
F
Sheet 1 of 1Project Number:
Project Location:
Project:
9186-184-00 Task 2032
Log of Hand Auger HA-4
Figure A-5
SWARR Station - Security Perimeter Maintenance Project
Renton, Washington
Ele
v
a
t
i
o
n
(
f
e
e
t
)
185
184
De
p
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h
(
f
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)
1
2
Te
s
t
i
n
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S
a
m
p
l
e
Gr
a
p
h
i
c
L
o
g
SAMPLE
MATERIAL
DESCRIPTION
Gr
o
u
p
Cla
s
s
i
f
i
c
a
t
i
o
n
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
REMARKS
Fin
e
s
Co
n
t
e
n
t
(
%
)
DateExcavated
Surface Elevation (ft)Vertical Datum Coordinate SystemHorizontal DatumLatitudeLongitude
TotalDepth (ft)9/27/2024 2
186NAVD88 47.463166-122.20554 Decimal DegreesWGS84
JSP/JX
Checked By TB
Groundwater not observed
Caving not observedEquipment Hand Auger/DCP
Logged By Excavator GeoEngineers, Inc.
Forest duff
Brown silty sand (dense, moist)
Boring terminated at approximately 0.5 foot bgs due to hand augerrefusal
DUFF
SM
1
DCP (15-pound hammer/20-inch drop) blowcountconverted to an equivalent SPT blowcount based onASTM STP 399
DCP = 50 (SPT >30)Soil probe rod penetrated approximately ½-inch
Notes: See Figure A-1 for explanation of symbols.The depths on the hand-augered boring logs are based on an average of measurements across the hand-auger and should be considered accurate to ½ foot.Coordinates Data Source: Horizontal approximated based on . Vertical approximated based on .
Da
t
e
:
1
0
/
3
1
/
2
4
P
a
t
h
:
P
:
\
9
\
9
1
8
6
1
8
4
\
G
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9
1
8
6
1
8
4
0
0
_
2
0
3
2
.
G
P
J
D
B
L
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b
r
a
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:
G
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7
.
G
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8
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T
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S
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P
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_
1
P
_
G
E
O
T
E
C
_
%
F
Sheet 1 of 1Project Number:
Project Location:
Project:
9186-184-00 Task 2032
Log of Hand Auger HA-5
Figure A-6
SWARR Station - Security Perimeter Maintenance Project
Renton, Washington
Ele
v
a
t
i
o
n
(
f
e
e
t
)
De
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(
f
e
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)
Te
s
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i
n
g
S
a
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p
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Gr
a
p
h
i
c
L
o
g
SAMPLE
MATERIAL
DESCRIPTION
Gr
o
u
p
Cla
s
s
i
f
i
c
a
t
i
o
n
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
REMARKS
Fin
e
s
Co
n
t
e
n
t
(
%
)
DateExcavated
Surface Elevation (ft)Vertical Datum Coordinate SystemHorizontal DatumLatitudeLongitude
TotalDepth (ft)9/27/2024 0.5
156NAVD88 47.463095-122.206579 Decimal DegreesWGS84
JSP/JX
Checked By TB
Groundwater not observed
Caving not observedEquipment Hand Auger/DCP
Logged By Excavator GeoEngineers, Inc.
Forest duff
Gray-brown silty sand (dense, moist)
Boring terminated at approximately 1.5 feet bgs due to hand augerrefusal
DUFF
SM
1SA
18
DCP (15-pound hammer/20-inch drop) blowcountconverted to an equivalent SPT blowcount based onASTM STP 399
DCP = 50 (SPT >30)43
Notes: See Figure A-1 for explanation of symbols.The depths on the hand-augered boring logs are based on an average of measurements across the hand-auger and should be considered accurate to ½ foot.Coordinates Data Source: Horizontal approximated based on . Vertical approximated based on .
Da
t
e
:
1
0
/
3
1
/
2
4
P
a
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h
:
P
:
\
9
\
9
1
8
6
1
8
4
\
G
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9
1
8
6
1
8
4
0
0
_
2
0
3
2
.
G
P
J
D
B
L
i
b
r
a
r
y
/
L
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r
a
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:
G
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O
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N
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R
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_
D
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_
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7
.
G
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8
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S
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P
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_
1
P
_
G
E
O
T
E
C
_
%
F
Sheet 1 of 1Project Number:
Project Location:
Project:
9186-184-00 Task 2032
Log of Hand Auger HA-6
Figure A-7
SWARR Station - Security Perimeter Maintenance Project
Renton, Washington
Ele
v
a
t
i
o
n
(
f
e
e
t
)
158
De
p
t
h
(
f
e
e
t
)
1
Te
s
t
i
n
g
S
a
m
p
l
e
Gr
a
p
h
i
c
L
o
g
SAMPLE
MATERIAL
DESCRIPTION
Gr
o
u
p
Cla
s
s
i
f
i
c
a
t
i
o
n
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
REMARKS
Fin
e
s
Co
n
t
e
n
t
(
%
)
DateExcavated
Surface Elevation (ft)Vertical Datum Coordinate SystemHorizontal DatumLatitudeLongitude
TotalDepth (ft)9/27/2024 1.5
159NAVD88 47.463089-122.206914 Decimal DegreesWGS84
JSP/JX
Checked By TB
Groundwater not observed
Caving not observedEquipment Hand Auger/DCP
Logged By Excavator GeoEngineers, Inc.
Brown silty sand with organic matter (dense, moist)
Boring terminated at approximately 1.25 feet bgs due to hand augerrefusal
SM
1
DCP (15-pound hammer/20-inch drop) blowcountconverted to an equivalent SPT blowcount based onASTM STP 399
DCP = 50 (SPT >30)Soil probe rod penetrated approximately ½-inch
Notes: See Figure A-1 for explanation of symbols.The depths on the hand-augered boring logs are based on an average of measurements across the hand-auger and should be considered accurate to ½ foot.Coordinates Data Source: Horizontal approximated based on . Vertical approximated based on .
Da
t
e
:
1
0
/
3
1
/
2
4
P
a
t
h
:
P
:
\
9
\
9
1
8
6
1
8
4
\
G
I
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\
9
1
8
6
1
8
4
0
0
_
2
0
3
2
.
G
P
J
D
B
L
i
b
r
a
r
y
/
L
i
b
r
a
r
y
:
G
E
O
E
N
G
I
N
E
E
R
S
_
D
F
_
S
T
D
_
U
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_
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N
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_
2
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1
7
.
G
L
B
/
G
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I
8
_
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S
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P
I
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_
1
P
_
G
E
O
T
E
C
_
%
F
Sheet 1 of 1Project Number:
Project Location:
Project:
9186-184-00 Task 2032
Log of Hand Auger HA-7
Figure A-8
SWARR Station - Security Perimeter Maintenance Project
Renton, Washington
Ele
v
a
t
i
o
n
(
f
e
e
t
)
160
De
p
t
h
(
f
e
e
t
)
1
Te
s
t
i
n
g
S
a
m
p
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e
Gr
a
p
h
i
c
L
o
g
SAMPLE
MATERIAL
DESCRIPTION
Gr
o
u
p
Cla
s
s
i
f
i
c
a
t
i
o
n
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
REMARKS
Fin
e
s
Co
n
t
e
n
t
(
%
)
DateExcavated
Surface Elevation (ft)Vertical Datum Coordinate SystemHorizontal DatumLatitudeLongitude
TotalDepth (ft)9/27/2024 1.25
161NAVD88 47.462747-122.206858 Decimal DegreesWGS84
JSP/JX
Checked By TB
Groundwater not observed
Caving not observedEquipment Hand Auger/DCP
Logged By Excavator GeoEngineers, Inc.
Brown silty sand with organic matter (dense, moist)
Boring terminated at approximately 0.75 feet bgs due to hand augerrefusal
SM
1SA
7
DCP (15-pound hammer/20-inch drop) blowcountconverted to an equivalent SPT blowcount based onASTM STP 399
DCP = 50 (SPT >30)Soil probe rod penetrated approximately ¼-inch47
Notes: See Figure A-1 for explanation of symbols.The depths on the hand-augered boring logs are based on an average of measurements across the hand-auger and should be considered accurate to ½ foot.Coordinates Data Source: Horizontal approximated based on . Vertical approximated based on .
Da
t
e
:
1
0
/
3
1
/
2
4
P
a
t
h
:
P
:
\
9
\
9
1
8
6
1
8
4
\
G
I
N
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\
9
1
8
6
1
8
4
0
0
_
2
0
3
2
.
G
P
J
D
B
L
i
b
r
a
r
y
/
L
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b
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a
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y
:
G
E
O
E
N
G
I
N
E
E
R
S
_
D
F
_
S
T
D
_
U
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J
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_
2
0
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.
G
L
B
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I
8
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T
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S
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P
I
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_
1
P
_
G
E
O
T
E
C
_
%
F
Sheet 1 of 1Project Number:
Project Location:
Project:
9186-184-00 Task 2032
Log of Hand Auger HA-8
Figure A-9
SWARR Station - Security Perimeter Maintenance Project
Renton, Washington
Ele
v
a
t
i
o
n
(
f
e
e
t
)
De
p
t
h
(
f
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)
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i
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g
S
a
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Gr
a
p
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i
c
L
o
g
SAMPLE
MATERIAL
DESCRIPTION
Gr
o
u
p
Cla
s
s
i
f
i
c
a
t
i
o
n
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
REMARKS
Fin
e
s
Co
n
t
e
n
t
(
%
)
DateExcavated
Surface Elevation (ft)Vertical Datum Coordinate SystemHorizontal DatumLatitudeLongitude
TotalDepth (ft)9/27/2024 0.75
165NAVD88 47.462187-122.206559 Decimal DegreesWGS84
JSP/JX
Checked By TB
Groundwater not observed
Caving not observedEquipment Hand Auger/DCP
Logged By Excavator GeoEngineers, Inc.
Brown silty sand with gravel (dense, moist)
Boring terminated at approximately 1 foot bgs due to hand augerrefusal
SM
1
DCP (15-pound hammer/20-inch drop) blowcountconverted to an equivalent SPT blowcount based onASTM STP 399
DCP = 50 (SPT >30)Soil probe rod penetrated approximately ¼-inch to½-inch
Notes: See Figure A-1 for explanation of symbols.The depths on the hand-augered boring logs are based on an average of measurements across the hand-auger and should be considered accurate to ½ foot.Coordinates Data Source: Horizontal approximated based on . Vertical approximated based on .
Da
t
e
:
1
0
/
3
1
/
2
4
P
a
t
h
:
P
:
\
9
\
9
1
8
6
1
8
4
\
G
I
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\
9
1
8
6
1
8
4
0
0
_
2
0
3
2
.
G
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D
B
L
i
b
r
a
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/
L
i
b
r
a
r
y
:
G
E
O
E
N
G
I
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E
E
R
S
_
D
F
_
S
T
D
_
U
S
_
J
U
N
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_
2
0
1
7
.
G
L
B
/
G
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I
8
_
T
E
S
T
P
I
T
_
1
P
_
G
E
O
T
E
C
_
%
F
Sheet 1 of 1Project Number:
Project Location:
Project:
9186-184-00 Task 2032
Log of Hand Auger HA-9
Figure A-10
SWARR Station - Security Perimeter Maintenance Project
Renton, Washington
Ele
v
a
t
i
o
n
(
f
e
e
t
)
166
De
p
t
h
(
f
e
e
t
)
1
Te
s
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i
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S
a
m
p
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e
Gr
a
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h
i
c
L
o
g
SAMPLE
MATERIAL
DESCRIPTION
Gr
o
u
p
Cla
s
s
i
f
i
c
a
t
i
o
n
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
REMARKS
Fin
e
s
Co
n
t
e
n
t
(
%
)
DateExcavated
Surface Elevation (ft)Vertical Datum Coordinate SystemHorizontal DatumLatitudeLongitude
TotalDepth (ft)9/27/2024 1
167NAVD88 47.461836-122.206475 Decimal DegreesWGS84
JSP/JX
Checked By TB
Groundwater not observed
Caving not observedEquipment Hand Auger/DCP
Logged By Excavator GeoEngineers, Inc.
0
10
20
30
40
50
60
70
80
90
100
0.0010.010.11101001000
PE
R
C
E
N
T
P
A
S
S
I
N
G
B
Y
W
E
I
G
H
T
GRAIN SIZE IN MILLIMETERS
U.S. STANDARD SIEVE SIZE
2”
SAND SILT OR CLAYCOBBLES
GRAVEL
COARSE MEDIUM FINECOARSE FINE
Boring Number
Depth
(feet)Soil Description
HA-2
HA-4
HA-6
HA-8
2
2
1.2
0.7
Silty sand (SM)
Well-graded gravel with silt and sand (GW-GM)
Silty sand (SM)
Silty sand (SM)
Symbol
Moisture
(%)
5
6
18
7
3/8”3” 1.5”#4 #10 #20 #40 #60 #1003/4”
Fi
g
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e
A
-
1
1
Si
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A
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SW
A
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S
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Ra
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,
W
a
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h
i
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t
o
n
09186-184-00 Date Exported: 10/16/2024
Note: This report may not be reproduced, except in full, without written approval of GeoEngineers, Inc. Test results are applicable only to the specific sample on which they were
performed, and should not be interpreted as representative of any other samples obtained at other times, depths or locations, or generated by separate operations or processes.
The grain size analysis results were obtained in general accordance with ASTM D6913. GeoEngineers 17425 NE Union Hill Road Ste 250, Redmond, WA 98052
#2001”#140
Attachment B
Report Limitations and Guidelines for Use
Memorandum to Puget Sound Energy
October 7, 2025
Page B-1
Attachment B
Report Limitations and Guidelines for Use1
This attachment provides information to help you manage your risks with respect to the use of this report.
READ THESE PROVISIONS CLOSELY
It is important to recognize that the geoscience practices (geotechnical engineering, geology and
environmental science) rely on professional judgment and opinion to a greater extent than other
engineering and natural science disciplines, where more precise and/or readily observable data may exist.
To help clients better understand how this difference pertains to our services, GeoEngineers includes the
following explanatory “limitations” provisions in its reports. Please confer with GeoEngineers if you need to
know more how these “Report Limitations and Guidelines for Use” apply to your project or site.
GEOTECHNICAL SERVICES ARE PERFORMED FOR SPECIFIC PURPOSES, PERSONS AND
PROJECTS
This report has been prepared for Puget Sound Energy and their authorized agents and for the Project(s)
specifically identified in the report. The information contained herein is not applicable to other sites or
projects.
GeoEngineers structures its services to meet the specific needs of its clients. No party other than the party
to whom this report is addressed may rely on the product of our services unless we agree to such reliance
in advance and in writing. Within the limitations of the agreed scope of services for the Project, and its
schedule and budget, our services have been executed in accordance with our Agreement with Puget Sound
Energy dated August 30, 2024 and generally accepted geotechnical practices in this area at the time this
report was prepared. We do not authorize, and will not be responsible for, the use of this report for any
purposes or projects other than those identified in the report.
SUBSURFACE CONDITIONS CAN CHANGE
This geotechnical or geologic report is based on conditions that existed at the time the study was performed.
The findings and conclusions of this report may be affected by the passage of time, by man-made events
such as construction on or adjacent to the site, new information or technology that becomes available
subsequent to the report date, or by natural events such as floods, earthquakes, slope instability or
groundwater fluctuations. If more than a few months have passed since issuance of our report or work
product, or if any of the described events may have occurred, please contact GeoEngineers before applying
this report for its intended purpose so that we may evaluate whether changed conditions affect the
continued reliability or applicability of our conclusions and recommendations.
INFORMATION PROVIDED BY OTHERS
GeoEngineers has relied upon certain data or information provided or compiled by others in the
performance of our services. Although we use sources that we reasonably believe to be trustworthy,
GeoEngineers cannot warrant or guarantee the accuracy or completeness of information provided or
compiled by others.
1 Developed based on material provided by GBA, GeoProfessional Business Associa�on; www.geoprofessional.org.