HomeMy WebLinkAboutAttach F - Preliminary Geotechnical Report
1101 Fawcett Avenue, Suite 200
Tacoma, Washington 98402
253.383.4940
February 12, 2025
City of Renton
1055 South Grady Way
Renton, Washington 98057
Attention: Jared McDonald, PE
Subject: Preliminary Geotechnical Design Report for 10% Design
Panther Creek Culvert Replacement Project
Renton, Washington
File No. 0693-093-00
Introduction and Background
This geotechnical report presents the preliminary results of GeoEngineers, Inc.’s (GeoEngineers)
geotechnical services for the Panther Creek Culvert Replacement Project. We understand the project is at
the 10% Design stage. Additional geotechnical analyses will occur during subsequent design stages.
We previously completed a preliminary geotechnical analysis in November 2023. At that time the preferred
design concept was a concrete box culvert. We understand that the current preferred design concept is a
concrete bridge. Our preliminary design considerations for 10 percent design are based on review of our
previous subsurface exploration and site observations.
The project site is located where Talbot Road crosses Panther Creek as shown in the Vicinity Map, Figure 1.
Talbot road is supported on fill which spans the Panther Creek valley. Panther Creek flows from east to west
through an existing 36-inch diameter fiberglass-reinforced pipe (FRP) located in the lower portion of the fill
prism. The layout of the site is shown in Figure 2.
We understand the proposed bridge will be approximately 100 feet long and about 57 feet wide. Most of
the fill that currently supports Talbot Road will be removed as a part of the project. The single-span bridge
will be supported by concrete abutments that bear on either 4- or 5-foot-diameter drilled shafts. Short wing
walls will border the abutments to the east and west. The type of walls utilized for the wing walls is presently
unknown and could comprise conventional concrete, structural earth walls (SEW) or soldier piles. Short
concrete diaphragm walls will be located between the concrete girders, adjacent to the abutment locations.
The approximate location of the proposed bridge is shown in Figure 2.
ATTACHMENT F
City of Renton | February 12, 2025 Page 2
File No. 0693-093-00
Scope of Services
Our services for this portion of the project include the following:
1. Complete subsurface explorations at the project site. This included three borings at the locations shown
in Figure 2. Copies of the boring logs are included in Appendix A.
2. Review documents previously completed by GeoEngineers in the project vicinity. These included cross
sections and photographs generated during a landslide investigation adjacent to the site in 2006.
These data are included in Appendix B.
3. Review published geologic maps of the site area.
4. Review photographs taken by GeoEngineers personnel during wetland mapping work in June, 2023.
5. Review historic information regarding former wooden trestle bridges that existed at the site until about
1933.
6. Review our November 2, 2023 preliminary geotechnical design letter.
7. Provide geotechnical support during development of the 10% Design, including the following tasks:
Provide a preliminary summary of potential soil, rock, and groundwater conditions based on
subsurface explorations completed at the site.
Develop preliminary geotechnical recommendations to support 10% Design. Recommendations
include preliminary axial and lateral capacity considerations for drilled shafts.
Provide preliminary recommendations for earthwork, including temporary and permanent slope
inclinations, suitability of onsite soil for reuse as structural fill, import fill criteria and fill compaction
criteria.
Evaluate potential construction considerations, including conceptual dewatering needs based on
subsurface conditions encountered in our explorations, as appropriate.
Develop preliminary lateral earth pressure criteria for design of abutment walls.
Published and Unpublished Information Review
GEOLOGIC MAP
Published geologic information for the project vicinity includes a U.S. Geological Survey Map titled “Geologic
Map of the Renton Quadrangle, King County, Washington” by Mullineaux (1965) and the “Geologic Map of
King County”, by Booth, Troost and Wisher (2007).
The geologic map indicates that Vashon glacial till is mapped over a broad region in the site vicinity, A thin
portion of the Panther Creek valley bottom, at the project site, is mapped as Renton Formation bedrock.
Vashon glacial till is a very dense mixture of silt, sand, gravel, and occasional cobbles/boulders that was
deposited at the base of the Vashon-age glacier as it moved from north to south through the site area.
Renton Formation bedrock comprises layers of arkosic sandstone, shale, mudstone, and coal.
City of Renton | February 12, 2025 Page 3
File No. 0693-093-00
PREVIOUS GEOENGINEERS INFORMATION
GeoEngineers evaluated a landslide just southwest of the project site in 2006. The landslide occurred on
the left stream bank of Panther Creek, just west of Talbot Road. The approximate location of this feature is
shown in Figure 2 and in Appendix B.
During our work we observed Renton Formation sedimentary bedrock on the left stream bank up to about
5 vertical feet from the top of the stream bank. The stream bank is about 30 feet in vertical height. A cross
section showing the distribution of the Renton Formation material is included in Appendix B. The rock
appeared weathered and fractured in photographs reviewed for this study.
HISTORIC BRIDGE INFORMATION
The historic information reviewed comprises photographs, inspection reports and drawings of the proposed
bridge replacement. This information dates to the early 1990s, from 1912 to 1934.
Historic information indicates that a wood trestle bridge existed at the site from at least 1912 to 1934. The
bridge was described as an 11 panel, wood trestle structure that was about 172 feet long and about 12 feet
wide. The attached photo is dated 1932 and appears to be looking along Talbot Road from south to north.
Photograph 1. Photo of Talbot Road Bridge in 1932, looking to the north.
A King County Engineer Office plan sheet, dated February 19, 1934, indicates the bridge was to be removed
and replaced with a fill embankment and a 12-inch-diameter, 30-foot-long culvert. Approximately
12,000 yards of material was to be excavated as a borrow source for the new embankment.
City of Renton | February 12, 2025 Page 4
File No. 0693-093-00
GeoEngineers Reconnaissance
GeoEngineers completed a reconnaissance of the site on June 28, 2023. We observed exposures of
weathered Renton Formation rock beneath the existing culvert and in the stream bank southwest of the
existing culvert. These exposures are shown in Photographs 2 and 3.
Photograph 2. Photograph of perched outfall, looking east from the Panther Creek stream channel.
Renton Formation Rock
City of Renton | February 12, 2025 Page 5
File No. 0693-093-00
Photograph 3. Photograph of exposed weathered Renton Formation rock. Exposure is looking south from the Panther Creek stream channel at the base of the left
stream bank.
Field Investigations
SUBSURFACE CONDITIONS
We completed three drilled borings at the site in August, 2023. The locations of our explorations are shown
in Figure 2. Copies of the boring logs are contained in Appendix A. Our interpretation of subsurface
conditions encountered in the borings are provided in the Cross Section, Figure 3.
Talbot Road, at the culvert location, is underlain by a significant thickness of loose fill. Approximately
15 inches of asphalt pavement was encountered in each boring, suggesting the fill has settled over time.
The east portion of the north-bound lane has several sags and depressions, suggesting settlement is
on-going.
Fill encountered in the borings comprised silty sand or sandy silt in a loose to medium dense/stiff condition.
The fill contains a moderate to very high percentage of silt. Organic debris was also occasionally observed
in the fill material. An obstruction within the fill was encountered in B-2 at a depth of about 26½ feet.
City of Renton | February 12, 2025 Page 6
File No. 0693-093-00
Weathered and unweathered Renton Formation rock was encountered in B-1 and B-3 below the loose fill.
The weathered Renton Formation material encountered in the borings was in a dense to very dense
condition. The unweathered Renton Formation material is in a very dense condition. Groundwater was not
observed in the borings.
Preliminary Geotechnical Considerations
EARTHWORK
Earthwork for the project will involve removing most of the loose fill to construct the proposed bridge. Large
diameter drilled shafts founded within the Renton Formation are proposed for support of the structure.
Some work within the Panther Creek stream and valley bottom area will also occur.
The existing fill contains a moderate to high percentage of fines and will be difficult to work during wet
weather conditions. The fill also appears to contain debris of an unknown nature (Boring B-2). The
earthwork contractor should be prepared to encounter and remove large debris from the excavation.
We recommend that earthwork take place during the normally dry late summer and early fall months, when
surface water flows within Panther Creek are lowest. The existing fill soils are not suitable for re-use as fill
on this project and may not be suited as structural fill for other projects based on the fines content and in
situ moisture content. We anticipate that the Renton Formation bedrock, particularly where weathered, can
be excavated using conventional construction equipment. The unweathered rock may require rippers or
impact hammers to remove from the site.
EROSION AND SEDIMENTATION CONTROL
The site soils are erosion sensitive. We recommend that a temporary erosion control plan be prepared in
accordance with applicable city and county standards. The plan should incorporate basic planning
principles, including provisions for site monitoring to evaluate the effectiveness of the erosion control
measures and repair and/or modify them as appropriate.
TEMPORARY AND PERMANENT SLOPES
The soils encountered at the site are classified as Type C soil in accordance with the provisions of Title
296-155 Washington Administrative Code (WAC), Part N, “Excavation, Trenching, and Shoring.” Temporary
slopes should be inclined at 1.5H:1V (horizontal to vertical) or flatter. Flatter cut slopes may be necessary
for longer slopes, where groundwater seepage is encountered, or in areas of current slope instability.
Additional recommendations should be developed during final design. We recommend that permanent cut
and fill slopes be constructed no steeper than 2H:1V.
FOUNDATION SUPPORT
We understand that 4- or 5-foot-diameter drilled shafts are being considered for preliminary design. We
anticipate the shafts will bear on unweathered Renton Formation rock. Preliminary axial and lateral capacity
considerations are provided below.
City of Renton | February 12, 2025 Page 7
File No. 0693-093-00
Axial Capacity
The performance of drilled shaft foundations can be greatly affected by the method of construction.
Softening, loosening or other changes in soil and rock conditions caused by the construction method can
result in a reduction in shaft resistance and an increase in shaft displacement. Therefore, evaluation of the
effects of the shaft construction procedure on resistance, including methods for preparing the bearing
surface should be considered in design. Based on our experience and preliminary analyses, we expect the
nominal tip resistance for shafts bearing on the Renton Formation will be greater than 400 kips per square
foot (ksf) and nominal frictional resistance within this deposit will be greater than 20 ksf. Rock cores and
laboratory testing should be completed prior to final design to confirm appropriate design values.
Lateral Capacity
Geotechnical design parameters for use in preliminary analyses of drilled shaft lateral capacity using LPILE
are provided in Table 1. Shafts spaced closer than five diameters (as measured center-to-center) apart will
experience lateral group effects that will result in a lower lateral load capacity for trailing rows of shafts with
respect to leading rows of shafts for an equivalent deflection. We recommend the lateral load capacity for
trailing shafts in a shaft group spaced less than five pile diameters apart be reduced in accordance with
the factors in Table 2.
TABLE 1. PRELIMINARY RECOMMENDED LPILE SOIL AND ROCK PARAMETERS
SOIL UNIT
APPROX.
LAYER EL
(TOP TO
BOTTOM)
SOIL MODEL
EFFECTIVE
UNIT
WEIGHT
(PCF)
FRICTION
ANGLE
(DEGREE)
UNDRAINED
SHEAR
STRENGTH
(PSF)
STIFFNESS
PARAMETER,
K
(PCI)
STRAIN
FACTOR
Ε50
Static Conditions
Fill 86 to 69.5 Sand
(Reese) 115 30 - 90 -
Weathered
bedrock 69.5 to 62 Sand
(Reese) 67.6 35 - 125 -
Intact Bedrock 62 to 50 Sand
(Reese) 77.6 42 - 125 -
Notes:
pcf = pounds per cubic foot; psf = pounds per square foot; pci = pounds per cubic inch
GWT = groundwater table
TABLE 2. SHAFT P-MULTIPLIERS, PM, FOR MULTIPLE ROW SHADING
SHAFT SPACING1
(IN TERMS OF SHAFT DIAMETER)
P-MULTIPLIERS, PM2, 3
ROW 1
(LEADING ROW)
ROW 2
(1ST TRAILING ROW)
ROW 3 AND HIGHER
(2ND TRAILING ROW)
3D 0.85 0.65 0.55
5D 1.0 0.85 0.80
Notes:
1 The P-multipliers in the table above are a function of the center-to-center spacing of shafts in the group in the direction of
loading expressed in multiples of the shaft diameter, D.
2 The values of Pm were developed for vertical shafts only.
3 The P-multipliers are dependent on the shaft spacing and the row number in the direction of the loading. To establish values of
Pm for other shaft spacing values, interpolation between values should be conducted.
City of Renton | February 12, 2025 Page 8
File No. 0693-093-00
Limitations
We have prepared this preliminary report for the exclusive use of the City of Renton and their authorized
agents. Within the limitations of scope, schedule and budget, our services have been executed in
accordance with generally accepted practices in the field of geotechnical consultation in this area at the
time this report was prepared. No warranty or other conditions, express or implied, should be understood.
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.
Please refer to Appendix D, “Report Limitations and Guidelines for Use” for additional information
pertaining to use of this report.
We appreciate the opportunity to provide geotechnical services on this project. Please contact us if you
have any questions or if we can provide any additional information.
Sincerely,
GeoEngineers, Inc.
Stephen W. Helvey, LG, LEG, LHG Debra C. Overbay, PE
Senior Engineering Geologist Associate
SWH:DCO:leh
Attachments
Figure 1. Vicinity Map
Figure 2. Site Plan
Figure 3. Cross Section
Appendix A. Field Explorations
Figure A-1 – Key to Exploration Logs
Figures A-2 through A-4 – Log of Borings
Appendix B. 2006 Landslide Site Plan and Cross Section
Appendix C. Report Limitations and Guidelines for Use
One electronic copy submitted
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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Vicinity Map
Figure 1
Panther Creek at Talbot Road S. Culvert
Replacement Project
Renton, Washington
3 Alpine Lak es
Wilder ness
Kent
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Coordinate System: NAD 1983 StatePlane Washington North FIPS 4601 Feet
Disclaimer: This figure was created for a specific purpose and project. Any use of this figure
for 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 contained
therein. The file containing this figure is a copy of a master document, the original of which is
retained by GeoEngineers and is the official document of record.
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Wetland A
B-3
B-1
B-2
Proposed Bridge Wing Walls
Proposed Bridge Footing
Proposed Bridge Footing
Proposed Bridge Wing Walls
N
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Figure 2
Site Plan
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Panther Creek at Talbot Road S. Culvert
Replacement Project
Renton, Washington
Legend
50
N
Source(s):
·Aerial from Google Earth Pro, dated 24/8/2022
·Survey or Background from KPFF, dated 7/14/2023
Coordinate System: Washington State Plane, North Zone, NAD83, US Foot
Disclaimer: This figure was created for a specific purpose and project. Any use of this figure for
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 contained
therein. The file containing this figure is a copy of a master document, the original of which is
retained by GeoEngineers and is the official document of record.
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B-1 Boring by GeoEngineers, Inc., 2023
B-
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(8
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B-
1
(3
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B-
2
(2
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Renton Formation Rock Renton Formation Rock
Fill (Loose)El
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Distance (Feet)
60
80
100
120
60
80
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0 20 40 60 80 100 120 140 160 180 200 220 240
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Weathered Renton
Formation Rock
Weathered Renton
Formation Rock
Figure 3
Cross Section A-A'
Legend
Note(s):
1.The subsurface conditions shown are based on interpolation between widely spaced
explorations and should be considered approximate; actual subsurface conditions may
vary from those shown.
Datum: NAVD88
Disclaimer: This figure was created for a specific purpose and project. Any use of this figure for 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 contained therein. The file containing this figure is a copy of
a master document, the original of which is retained by GeoEngineers and is the official document of record.
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Groundwater Measured in Piezometer
Renton Formation rock
Fill
Weathered Renton Formation Rock
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20
Boring
Soil Classification
Blow Count
Bo
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I
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(O
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)
Inferred Soil Contact
Panther Creek at Talbot Road S. Culvert Replacement
Project
Renton, Washington
or??
Asphalt
Appendix A
Field Explorations
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
FINE
GRAINED
SOILS
SILTS AND
CLAYS
NOTE: Multiple symbols are used to indicate borderline or dual soil classifications
MORE THAN 50%
RETAINED ON
NO. 200 SIEVE
MORE THAN 50%
PASSING
NO. 200 SIEVE
GRAVEL
AND
GRAVELLY
SOILS
SC
LIQUID LIMIT
LESS THAN 50
(APPRECIABLE AMOUNT
OF FINES)
(APPRECIABLE AMOUNT
OF FINES)
COARSE
GRAINED
SOILS
MAJOR DIVISIONS GRAPH LETTER
GM
GC
ML
CL
OL
SILTS AND
CLAYS
SANDS WITH
FINES
SAND
AND
SANDY
SOILS
MH
CH
OH
PT
(LITTLE OR NO FINES)
CLEAN SANDS
GRAVELS WITH
FINES
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 COARSE
FRACTION RETAINED
ON NO. 4 SIEVE
MORE THAN 50%
OF COARSE
FRACTION PASSING
ON NO. 4 SIEVE
SILTY GRAVELS, GRAVEL - SAND -SILT MIXTURES
POORLY-GRADED GRAVELS,GRAVEL - SAND MIXTURES
LIQUID LIMIT GREATER
THAN 50
Continuous Coring
Bulk or grab
Direct-Push
Piston
Shelby tube
Standard Penetration Test (SPT)
Contact between soil of the same geologic
unit
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 be
representative of subsurface conditions at other locations or times.
Groundwater Contact
Blowcount is recorded for driven samplers as the number of
blows 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 the
hammer.
Key to Exploration Logs
Figure A-1
Sampler Symbol Descriptions
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 Sheen
Slight Sheen
Moderate Sheen
Heavy Sheen
Laboratory / Field Tests
2.4-inch I.D. split barrel / Dames & Moore (D&M)
%F
%G
AL
CA
CP
CS
DD
DS
HA
MC
MD
Mohs
OC
PM
PI
PL
PP
SA
TX
UC
UU
VS
Sheen Classification
NS
SS
MS
HS
Percent fines
Percent gravel
Atterberg limits
Chemical analysis
Laboratory compaction test
Consolidation test
Dry density
Direct shear
Hydrometer analysis
Moisture content
Moisture content and dry density
Mohs hardness scale
Organic content
Permeability or hydraulic conductivity
Plasticity index
Point lead test
Pocket penetrometer
Sieve analysis
Triaxial compression
Unconfined compression
Unconsolidated undrained triaxial compression
Vane shear
Rev 01/2022
Hard drilling
49
49
45
17
30
19
33
Approximately 15 inches of asphalt concrete
pavement
Gray silty sand with gravel (loose, moist) (fill)
Gray silty sand (loose, moist) (fill)
Light gray weathered sandstone (Renton formation)
Light gray/white sandstone/siltstone (Renton
formation)
1
%F
2
MC
3
4
%F
5
6
%F
6
9
10
16
14
14
6
4
6
45
29
36
AC
SM
SM
RX
RX
Notes:
36.5 PW
SH Holocene Drilling, Inc. Hollow-stem Auger
D-50 Truck-mountedDrilling
EquipmentAutohammer
140 (lbs) / 30 (in) Drop
WA State Plane North
NAD83 (feet)
1299470
165449
97
NAVD88
Easting (X)
Northing (Y)
Start Total
Depth (ft)
Logged By
Checked By
End
Surface Elevation (ft)
Vertical Datum
Drilled
Hammer
Data
System
Datum
Driller Drilling
Method
Groundwater not observed at time of exploration
8/25/20238/25/2023
Note: See Figure A-1 for explanation of symbols.
Coordinates Data Source: Horizontal approximated based on Topographic Survey. Vertical approximated based on Topographic Survey.
Sheet 1 of 2Project Number:
Project Location:
Project:
0693-093-00
Log of Boring B-1
Figure A-2
Panther Creek Culvert
Renton, Washington
Da
t
e
:
1
0
/
2
7
/
2
3
P
a
t
h
:
\
\
G
E
O
E
N
G
I
N
E
E
R
S
.
C
O
M
\
W
A
N
\
P
R
O
J
E
C
T
S
\
0
\
0
6
9
3
0
9
3
\
G
I
N
T
\
0
6
9
3
0
9
3
0
0
.
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
S
_
J
U
N
E
_
2
0
1
7
.
G
L
B
/
G
E
I
8
_
G
E
O
T
E
C
H
_
S
T
A
N
D
A
R
D
_
%
F
_
N
O
_
G
W
REMARKS
Fi
n
e
s
Co
n
t
e
n
t
(
%
)
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
FIELD DATA
MATERIAL
DESCRIPTION
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Re
c
o
v
e
r
e
d
(
i
n
)
In
t
e
r
v
a
l
Bl
o
w
s
/
f
o
o
t
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
De
p
t
h
(
f
e
e
t
)
0
5
10
15
20
25
30
35
Gr
a
p
h
i
c
L
o
g
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
El
e
v
a
t
i
o
n
(
f
e
e
t
)
95
90
85
80
75
70
65
Very hard drilling71750/6"
Sheet 2 of 2Project Number:
Project Location:
Project:
0693-093-00
Log of Boring B-1 (continued)
Figure A-2
Panther Creek Culvert
Renton, Washington
Da
t
e
:
1
0
/
2
7
/
2
3
P
a
t
h
:
\
\
G
E
O
E
N
G
I
N
E
E
R
S
.
C
O
M
\
W
A
N
\
P
R
O
J
E
C
T
S
\
0
\
0
6
9
3
0
9
3
\
G
I
N
T
\
0
6
9
3
0
9
3
0
0
.
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
S
_
J
U
N
E
_
2
0
1
7
.
G
L
B
/
G
E
I
8
_
G
E
O
T
E
C
H
_
S
T
A
N
D
A
R
D
_
%
F
_
N
O
_
G
W
REMARKS
Fi
n
e
s
Co
n
t
e
n
t
(
%
)
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
FIELD DATA
MATERIAL
DESCRIPTION
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Re
c
o
v
e
r
e
d
(
i
n
)
In
t
e
r
v
a
l
Bl
o
w
s
/
f
o
o
t
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
De
p
t
h
(
f
e
e
t
)
35
Gr
a
p
h
i
c
L
o
g
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
El
e
v
a
t
i
o
n
(
f
e
e
t
)
52
16
18
11
18
Approximately 15 inches of asphalt concrete
pavement
Brown gravel with silt and sand (medium dense, moist)
Orange-gray sandy silt with gravel (medium stiff, moist)
Gray sandy silt with gravel (medium stiff, moist)
Gray/green silty fine sand with gravel (loose, moist)
Met refusal at approximately 26½ feet on concrete
blocks?
1
%F
2
3
%F
4
5
MC
18
18
18
18
18
7
7
4
9
25
AC
GM
ML
ML
SM
Notes:
26.5 PW
SH Holocene Drilling, Inc. Hollow-stem Auger
D-50 Truck-mountedDrilling
EquipmentAutohammer
140 (lbs) / 30 (in) Drop
WA State Plane North
NAD83 (feet)
1299468
165385
97
NAVD88
Easting (X)
Northing (Y)
Start Total
Depth (ft)
Logged By
Checked By
End
Surface Elevation (ft)
Vertical Datum
Drilled
Hammer
Data
System
Datum
Driller Drilling
Method
Groundwater not observed at time of exploration
8/24/20238/24/2023
Note: See Figure A-1 for explanation of symbols.
Coordinates Data Source: Horizontal approximated based on Topographic Survey. Vertical approximated based on Topographic Survey.
Sheet 1 of 1Project Number:
Project Location:
Project:
0693-093-00
Log of Boring B-2
Figure A-3
Panther Creek Culvert
Renton, Washington
Da
t
e
:
1
0
/
2
7
/
2
3
P
a
t
h
:
\
\
G
E
O
E
N
G
I
N
E
E
R
S
.
C
O
M
\
W
A
N
\
P
R
O
J
E
C
T
S
\
0
\
0
6
9
3
0
9
3
\
G
I
N
T
\
0
6
9
3
0
9
3
0
0
.
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
S
_
J
U
N
E
_
2
0
1
7
.
G
L
B
/
G
E
I
8
_
G
E
O
T
E
C
H
_
S
T
A
N
D
A
R
D
_
%
F
_
N
O
_
G
W
REMARKS
Fi
n
e
s
Co
n
t
e
n
t
(
%
)
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
FIELD DATA
MATERIAL
DESCRIPTION
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Re
c
o
v
e
r
e
d
(
i
n
)
In
t
e
r
v
a
l
Bl
o
w
s
/
f
o
o
t
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
De
p
t
h
(
f
e
e
t
)
0
5
10
15
20
25
Gr
a
p
h
i
c
L
o
g
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
El
e
v
a
t
i
o
n
(
f
e
e
t
)
95
90
85
80
75
With wood fragments
Big tree root
42
39
15
27
Approximately 15 inches of asphalt concrete
pavement
Brown gravel with silt, sand and boulder (medium
dense, moist)
Orange-gray silty sand with gravel (loose, moist) (fill)
Gray silty sand with gravel and organic matter (wood)
(medium dense, moist) (fill)
Red-brown weathered sandstone (Renton formation)
Light gray sandstone/siltstone (Renton formation)
1
2
%F
3%F
4
5
6
4
7
18
4
12
11
9
6
20
6
50/5"
50/4.5"
AC
GP-GM
SM
SM
RX
RX
Notes:
36 PW
SH Holocene Drilling, Inc. Hollow-stem Auger
D-50 Truck-mountedDrilling
EquipmentAutohammer
140 (lbs) / 30 (in) Drop
WA State Plane North
NAD83 (feet)
Undetermined
NAVD88
Easting (X)
Northing (Y)
Start Total
Depth (ft)
Logged By
Checked By
End
Surface Elevation (ft)
Vertical Datum
Drilled
Hammer
Data
System
Datum
Driller Drilling
Method
Groundwater not observed at time of exploration
8/24/20238/24/2023
Note: See Figure A-1 for explanation of symbols.
Coordinates Data Source: Horizontal approximated based on Topographic Survey. Vertical approximated based on Topographic Survey.
Sheet 1 of 2Project Number:
Project Location:
Project:
0693-093-00
Log of Boring B-3
Figure A-4
Panther Creek Culvert
Renton, Washington
Da
t
e
:
1
0
/
2
7
/
2
3
P
a
t
h
:
\
\
G
E
O
E
N
G
I
N
E
E
R
S
.
C
O
M
\
W
A
N
\
P
R
O
J
E
C
T
S
\
0
\
0
6
9
3
0
9
3
\
G
I
N
T
\
0
6
9
3
0
9
3
0
0
.
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
S
_
J
U
N
E
_
2
0
1
7
.
G
L
B
/
G
E
I
8
_
G
E
O
T
E
C
H
_
S
T
A
N
D
A
R
D
_
%
F
_
N
O
_
G
W
REMARKS
Fi
n
e
s
Co
n
t
e
n
t
(
%
)
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
FIELD DATA
MATERIAL
DESCRIPTION
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Re
c
o
v
e
r
e
d
(
i
n
)
In
t
e
r
v
a
l
Bl
o
w
s
/
f
o
o
t
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
De
p
t
h
(
f
e
e
t
)
0
5
10
15
20
25
30
35
Gr
a
p
h
i
c
L
o
g
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
El
e
v
a
t
i
o
n
(
f
e
e
t
)
650/4"
Sheet 2 of 2Project Number:
Project Location:
Project:
0693-093-00
Log of Boring B-3 (continued)
Figure A-4
Panther Creek Culvert
Renton, Washington
Da
t
e
:
1
0
/
2
7
/
2
3
P
a
t
h
:
\
\
G
E
O
E
N
G
I
N
E
E
R
S
.
C
O
M
\
W
A
N
\
P
R
O
J
E
C
T
S
\
0
\
0
6
9
3
0
9
3
\
G
I
N
T
\
0
6
9
3
0
9
3
0
0
.
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
S
_
J
U
N
E
_
2
0
1
7
.
G
L
B
/
G
E
I
8
_
G
E
O
T
E
C
H
_
S
T
A
N
D
A
R
D
_
%
F
_
N
O
_
G
W
REMARKS
Fi
n
e
s
Co
n
t
e
n
t
(
%
)
Mo
i
s
t
u
r
e
Co
n
t
e
n
t
(
%
)
FIELD DATA
MATERIAL
DESCRIPTION
Sa
m
p
l
e
N
a
m
e
Te
s
t
i
n
g
Re
c
o
v
e
r
e
d
(
i
n
)
In
t
e
r
v
a
l
Bl
o
w
s
/
f
o
o
t
Co
l
l
e
c
t
e
d
S
a
m
p
l
e
De
p
t
h
(
f
e
e
t
)
35
Gr
a
p
h
i
c
L
o
g
Gr
o
u
p
Cl
a
s
s
i
f
i
c
a
t
i
o
n
El
e
v
a
t
i
o
n
(
f
e
e
t
)
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 FINECOARSEFINE
Boring Number
Depth
(feet)Soil Description
B-1
B-2
B-2
20
5
15
Silty sand with gravel (SM)
Sandy silt with gravel (ML)
Silty sand (SM)
Symbol
Moisture
(%)
19
18
11
3/8”3” 1.5”#4 #10 #20 #40 #60 #1003/4”
Fi
g
u
r
e
A
-
5
Si
e
v
e
A
n
a
l
y
s
i
s
R
e
s
u
l
t
s
Pa
n
t
h
e
r
C
r
e
e
k
Re
n
t
o
n
,
W
a
s
h
i
n
g
t
o
n
00693-093-00 Date Exported: 09/12/2023
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
Appendix B
2006 Landslide Site Plan and Cross Section
Appendix C
Report Limitations and Guidelines for Use
City of Renton | February 12, 2025 Page C-1
File No. 0693-093-00
Appendix C
Report Limitations and Guidelines For Use1
This appendix 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 City of Renton 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 City of
Renton dated May 19, 2023 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.
A GEOTECHNICAL ENGINEERING OR GEOLOGIC REPORT IS BASED ON A UNIQUE SET OF
PROJECT-SPECIFIC FACTORS
This report has been prepared for the proposed Panther Creek Culvert Replacement Project. GeoEngineers
considered a number of unique, project-specific factors when establishing the scope of services for this
project and report. Unless GeoEngineers specifically indicates otherwise, it is important not to rely on this
report if it was:
■ Not prepared for you,
■ Not prepared for your project,
■ Not prepared for the specific site explored, or
■ Completed before important project changes were made.
1 Developed based on material provided by GBA, GeoProfessional Business Association; www.geoprofessional.org.
City of Renton | February 12, 2025 Page C-2
File No. 0693-093-00
For example, changes that can affect the applicability of this report include those that affect:
■ The function of the proposed structure;
■ Elevation, configuration, location, orientation, or weight of the proposed structure;
■ Composition of the design team; or
■ Project ownership.
If changes occur after the date of this report, GeoEngineers cannot be responsible for any consequences
of such changes in relation to this report unless we have been given the opportunity to review our
interpretations and recommendations. Based on that review, we can provide written modifications or
confirmation, as appropriate.
ENVIRONMENTAL CONCERNS ARE NOT COVERED
Unless environmental services were specifically included in our scope of services, this report does not
provide any environmental findings, conclusions, or recommendations, including but not limited to, the
likelihood of encountering underground storage tanks or regulated contaminants.
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.
GEOTECHNICAL AND GEOLOGIC FINDINGS ARE PROFESSIONAL OPINIONS
Our interpretations of subsurface conditions are based on field observations from widely spaced sampling
locations at the site. Site exploration identifies the specific subsurface conditions only at those points where
subsurface tests are conducted or samples are taken. GeoEngineers reviewed field and laboratory data
and then applied its professional judgment to render an informed opinion about subsurface conditions at
other locations. Actual subsurface conditions may differ, sometimes significantly, from the opinions
presented in this report. Our report, conclusions and interpretations are not a warranty of the actual
subsurface conditions.
GEOTECHNICAL ENGINEERING REPORT RECOMMENDATIONS ARE NOT FINAL
We have developed the following recommendations based on data gathered from subsurface
investigation(s). These investigations sample just a small percentage of a site to create a snapshot of the
subsurface conditions elsewhere on the site. Such sampling on its own cannot provide a complete and
accurate view of subsurface conditions for the entire site. Therefore, the recommendations included in this
report are preliminary and should not be considered final. GeoEngineers’ recommendations can be
finalized only by observing actual subsurface conditions revealed during construction. GeoEngineers
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cannot assume responsibility or liability for the recommendations in this report if we do not perform
construction observation.
We recommend that you allow sufficient monitoring, testing and consultation during construction by
GeoEngineers to confirm that the conditions encountered are consistent with those indicated by the
explorations, to provide recommendations for design changes if the conditions revealed during the work
differ from those anticipated, and to evaluate whether earthwork activities are completed in accordance
with our recommendations. Retaining GeoEngineers for construction observation for this project is the most
effective means of managing the risks associated with unanticipated conditions. If another party performs
field observation and confirms our expectations, the other party must take full responsibility for both the
observations and recommendations. Please note, however, that another party would lack our project-
specific knowledge and resources.
A GEOTECHNICAL ENGINEERING OR GEOLOGIC REPORT COULD BE SUBJECT TO
MISINTERPRETATION
Misinterpretation of this report by members of the design team or by contractors can result in costly
problems. GeoEngineers can help reduce the risks of misinterpretation by conferring with appropriate
members of the design team after submitting the report, reviewing pertinent elements of the design team’s
plans and specifications, participating in pre-bid and preconstruction conferences, and providing
construction observation.
DO NOT REDRAW THE EXPLORATION LOGS
Geotechnical engineers and geologists prepare final boring and testing logs based upon their interpretation
of field logs and laboratory data. The logs included in a geotechnical engineering or geologic report should
never be redrawn for inclusion in architectural or other design drawings. Photographic or electronic
reproduction is acceptable, but separating logs from the report can create a risk of misinterpretation.
GIVE CONTRACTORS A COMPLETE REPORT AND GUIDANCE
To help reduce the risk of problems associated with unanticipated subsurface conditions, GeoEngineers
recommends giving contractors the complete geotechnical engineering or geologic report, including these
“Report Limitations and Guidelines for Use.” When providing the report, you should preface it with a clearly
written letter of transmittal that:
■ Advises contractors that the report was not prepared for purposes of bid development and that its
accuracy is limited; and
■ Encourages contractors to conduct additional study to obtain the specific types of information they
need or prefer.
CONTRACTORS ARE RESPONSIBLE FOR SITE SAFETY ON THEIR OWN CONSTRUCTION
PROJECTS
Our geotechnical recommendations are not intended to direct the contractor’s procedures, methods,
schedule, or management of the work site. The contractor is solely responsible for job site safety and for
managing construction operations to minimize risks to on-site personnel and adjacent properties.
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BIOLOGICAL POLLUTANTS
GeoEngineers’ Scope of Work specifically excludes the investigation, detection, prevention, or assessment
of the presence of Biological Pollutants. Accordingly, this report does not include any interpretations,
recommendations, findings, or conclusions regarding the detecting, assessing, preventing or abating of
Biological Pollutants, and no conclusions or inferences should be drawn regarding Biological Pollutants as
they may relate to this project. The term “Biological Pollutants” includes, but is not limited to, molds, fungi,
spores, bacteria, and viruses, and/or any of their byproducts.
A Client that desires these specialized services is advised to obtain them from a consultant who offers
services in this specialized field.
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.