HomeMy WebLinkAboutAttach C.2 - 10 Pct Hydraulic Design
10 Percent Hydraulic Design
Panther Creek at Talbot Road South Culvert
Replacement Project
Renton, Washington
for
City of Renton
May 30, 2025
1101 Fawcett Avenue, Suite 200
Tacoma, Washington 98402
253.386.4940
ATTACHMENT C.2
10 Percent Hydraulic Design
Panther Creek at Talbot Road South Culvert
Replacement Project
Renton, Washington
File No. 0693-093-00
May 30, 2025
Prepared for:
City of Renton
1055 South Grady Way
Renton, Washington 98057
Attention: Jared McDonald, PE
Prepared by:
GeoEngineers, Inc.
1101 Fawcett Avenue, Suite 200
Tacoma, Washington 98402
253.383.4940
Ken T. Fellows, PE
Senior Civil Engineer
David B. Conlin, PWS
Associate Ecologist
KTF:DBC:tlm
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.
City of Renton | May 30, 2025 Page i
File No. 0693-093-00
Table of Contents
1.0 Introduction .............................................................................................................................. 1
2.0 Overview of Existing Site Conditions ........................................................................................... 1
2.1 Stream ......................................................................................................................................................... 1
2.1.1 Watershed Characteristics .............................................................................................................. 1
2.1.2 Site Conditions................................................................................................................................. 1
2.1.3 Federal Emergency Management Agency (FEMA) Floodplain Mapping ....................................... 3
2.1.4 Hydrology ......................................................................................................................................... 3
2.2 Summary of Geotechnical Investigation .................................................................................................... 4
2.3 Infrastructure .............................................................................................................................................. 5
2.3.1 Road ................................................................................................................................................. 5
2.3.2 Utilities ............................................................................................................................................. 5
3.0 Channel Hydraulics ................................................................................................................... 5
4.0 Stream Design .......................................................................................................................... 6
4.1 Stream Channel .......................................................................................................................................... 6
4.1.1 Alignment ......................................................................................................................................... 6
4.1.2 Profile ............................................................................................................................................... 6
4.1.3 Channel Section .............................................................................................................................. 7
4.1.4 Stream Substrate ............................................................................................................................ 7
4.1.5 Temporary Stream Bypass .............................................................................................................. 7
4.1.6 Habitat Features .............................................................................................................................. 7
4.2 Crossing Structure Considerations ............................................................................................................ 9
4.2.1 Crossing Structure Minimum Width and Vertical Clearance ......................................................... 9
4.2.2 Crossing Structure Scour ................................................................................................................ 9
4.2.3 Crossing Structure Foundation .................................................................................................... 10
4.3 Permitting ................................................................................................................................................. 10
4.4 Construction ............................................................................................................................................. 10
5.0 Estimate of Construction Cost .................................................................................................. 11
6.0 Stream Related Data Gaps ...................................................................................................... 11
7.0 References .............................................................................................................................. 11
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File No. 0693-093-00
List of Figures
Figure 1. Vicinity Map
Figure 2. Plan View
Appendices
Appendix A. Stream Field Report
Appendix B. FEMA Flood Panel
Appendix C. Hydraulic Modeling Summary Results
Figure C-1. Panther Creek Culvert Replacement Existing Conditions 2-Year Flow Velocity
Figure C-2. Panther Creek Culvert Replacement 10 Percent Design Conditions 2-Year Flow Velocity
Figure C-3. Panther Creek Culvert Replacement Existing Conditions Water Surface Profiles
Figure C-4. Panther Creek Culvert Replacement 10 Percent Design Water Surface Profiles
Appendix D. 10 Percent Design Stream Plans
Appendix E. 10 Percent Design Opinion of Probable Construction Cost
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File No. 0693-093-00
1.0 Introduction
This 10 Percent Hydraulic Design Report was prepared by GeoEngineers, Inc. (GeoEngineers) on behalf of
the City of Renton (City) in support of the Panther Creek at Talbot Road South Culvert Replacement Project
(project) in Renton, Washington. The City is proposing to replace the existing culvert conveying Panther
Creek from east to west under Talbot Road South to improve fish passage and reduce risk of failure of the
crossing structure. The proposed culvert replacement project, as envisioned at the 10 percent design stage,
is to replace the existing 32-inch-diameter pipe culvert with a 59-foot-wide by 110-foot-long bridge. A bridge
of this size was selected as the preferred alternative from several culvert and bridge alternates. The existing
culvert and road embankment would be removed. The creek would be restored to a more natural open
condition close to its current alignment, and the creek profile would be adjusted to have slope similar to
the upstream reach to eliminate the current perched outlet and scour hole at the culvert outlet.
KPFF Consulting Engineers, Inc. (KPFF), as a subconsultant to GeoEngineers, is preparing Memoranda
addressing 10 Percent Bridge Design and 10 Percent Civil Engineering Design. GeoEngineers has also
prepared a separate 10% Geotechnical Design Report in support of the project.
The project site is located at Talbot Road South, between South 38th Court and South 177th Street, in
Renton, Washington (Figure 1, Vicinity Map). The site is just northeast of the Valley Medical Center and the
intersections of State Route (SR) 167 and South 180th Street.
2.0 Overview of Existing Site Conditions
2.1 STREAM
The Panther Creek Stream Assessment (see Appendix A, Stream Field Report) contains observations about
existing site conditions based on GeoEngineers’ site visits completed in June and July 2023.
2.1.1 Watershed Characteristics
The Panther Creek watershed covers 1.79 square miles that includes a mix of natural forested and wetland
areas, as well as many residential developments. Panther Creek extends upstream of Talbot Road South
approximately 2.8 miles to the southeast. The first 0.7 miles of creek upstream of the crossing lies in a
confined ravine that has an increase in elevation from approximately 70 feet to approximately 400 feet,
resulting in an average valley slope of approximately 8 percent (City of Renton 2023). Over the remaining
2.1 miles, the creek flows at gentler slope of 1 to 2 percent over an upland plateau, where the watershed
eventually reaches a high point of approximately 475 feet elevation (City of Renton 2023). Approximately
850 feet downstream of the project crossing, the confined ravine topography transitions to a wider valley
bottom as the creek approaches the greater Green River valley (City of Renton 2023). In the vicinity of the
project crossing, the average creek slope is approximately 4 percent (City of Renton 2023).
2.1.2 Site Conditions
KPFF completed a topographic survey of the project site in July 2023 (see Figure 2, Plan View). The survey
extended approximately 300 feet upstream and 300 feet downstream of Talbot Road South. The vertical
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datum for the survey was North American Vertical Datum of 1988 (NAVD88) (feet). Project specific
elevations noted in the remainder of this report are expressed in feet, NAVD88 vertical datum.
The ravine in the vicinity of the project crossing is mapped by Mullineaux (1965) as the Renton Formation
that is characterized by Arkosic sandstone, mudstone and shale. Areas surrounding the project crossing
are mapped as glacial till, consisting of compact, unsorted sand, silt, clay and gravel.
The existing culvert (Washington Department of Fish and Wildlife [WDFW] Site ID: 931933) is a 32-inch-
diameter corrugated steel pipe, approximately 136 feet long, with a slope of approximately 4 percent (see
Figure 2). The culvert is in poor condition. The bottom of the culvert is completely scoured away in places.
This creates a risk of rapid and total failure during a flood event due to water leaking from the culvert, then
flowing through pipe bedding and road embankment material. The culvert appears to have been lined with
fiberglass at some time in the past; however, only a few patches of remnant fiberglass material remain.
Replacement of the culvert is warranted due to its poor condition and also because the culvert downstream
end is elevated (perched) approximately 4 feet above the receiving pool, which creates a total barrier to
passage of salmonids.
The existing culvert is undersized, causing upstream backwatering during flood events. Backwatering of
flows appear to have resulted in deposits of sediment upstream of the culvert that are up to approximately
2 to 3 feet thick, causing the apparent stream bottom to widen as the ravine is filled over time.
Based on several Wolman pebble counts completed during GeoEngineers’ site visit (Appendix A), the
existing streambed immediately adjacent to the culvert is a mix of sand, gravel, cobbles and boulders, with
a D50 of 1.5 to 3 inches and a D95 of 6 to 9 inches.
In general, our observation of the stream did not note areas of substantial streambank erosion or channel
incision. The stream channel appears to be relatively stable, both horizontally and vertically; however, In
the area just upstream of the existing culvert, the existing channel alignment appears to be undergoing
slow, but progressive migration to the north, eroding the base of the steep slopes on private property. This
channel migration is creating a condition where the channel upstream of the culvert overshoots the culvert
entrance and must then curve back sharply to reach the culvert entrance. At the entrance, flow must turn
nearly 90 degrees over a very short distance to flow into the culvert.
A reference reach is intended to be a section of creek that is relatively unaffected by artificial conditions or
infrastructure that can serve as a guide to design new or restored channels. For this project, a reference
reach approximately 100 feet long was identified approximately 450 feet upstream of the project crossing.
The reference reach has a single thread channel located within a meander bend with the apex oriented
along the right bank. The reach has an average slope of 4.4 percent and exhibits a step-pool bedform. An
approximately 35-foot-long portion of the reference reach appears more as a pool-riffle morphology with
steps upstream of pools. Water surface drops of several inches occur across these steps. Pools ranged
from approximately 2 to 5 feet long with a maximum depth measured of 5 inches. Streambed material in
the reference reach consists of small- to medium-sized cobbles with coarse gravels and occasional small
boulders. Fine to coarse sands were observed along channel bank toes with a fine to coarse gravel armor,
or within undercut pools. A Wolman pebble count indicated a streambed sediment D50 of 2.3 inches and a
D95 of 8.5 inches. There appears to be a natural and on-going supply of appropriately sized sediment from
upstream areas to the project reach. No large wood was present in the reference reach.
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The average design bankfull width (BFW) for sizing the proposed channel and structure opening is 9.5 feet.
The field report included in Appendix A includes a description of how this value was identified. The WDFW
culvert report for the crossing (WDFW 2022) notes a bankfull width of 4.5 meters (15 feet). This value likely
reflects conditions near and potentially influenced by the existing culvert. The GeoEngineers’ field team
found that further from the crossing both upstream and downstream bankfull width measurements were
smaller and likely more typical of the local Panther Creek channel.
A small wetland is located on the right bank floodplain bench just downstream of the culvert, likely
supported by groundwater seepage (GeoEngineers 2023a). No other wetlands were identified with the
project reach.
2.1.3 Federal Emergency Management Agency (FEMA) Floodplain Mapping
Panther Creek at Talbot Road South is within a FEMA Zone X, indicating that it is unmapped by either
detailed or approximate methods and considered to be within an area of minimal flood hazard risk, as
shown in the FIRMette panel (FEMA 2023) included in Appendix B, FEMA Flood Panel.
2.1.4 Hydrology
Hydrology within the Panther Creek watershed is understood to be highly influenced by urban development.
Basin hydrology was assessed using multiple simple methods to obtain a range of several peak flow
estimates for potential use in analysis and design. These simple methods included conducting a review of
nearby gages to complete a basin transfer analysis, calculating regional regression equation values,
completing a watershed scale rainfall-runoff continuous flow model analysis and reviewing existing
literature. Table 1 summarizes the results of these methods. Panther Creek does not have a stream gaging
station to provide a record of past flows.
GeoEngineers performed the basin transfer analysis using stream gage data from the King County gage
with site ID 31c located along Molasses Creek (King County 2023). The gage is located approximately
2.9 miles northeast of the Panther Creek project crossing at Talbot Road South. The Molasses Creek
watershed has an area of approximately 98 percent of Panther Creek at the project location. Visual
inspection of aerial imagery within the Molasses Creek watershed suggests it is similar to Panther Creek.
The results of the basin transfer analysis were lower than expected for Panther Creek given the size of the
stream.
Regression equations are not valid for basins with more than 5 percent impervious area and the Panther
Creek watershed has an estimated impervious area of 30 percent. However, they are very easy to apply
and can provide a low-end estimate of peak flow hydrology for a developed watershed. The results of this
method were lower than those from the basin transfer method for both the 2- and 100-year events but
slightly larger for the 500-year event.
Rainfall-runoff modeling was carried out using MGSFlood, utilizing United Stated Geological Survey (USGS)
soil data and land use data from the cities of Renton and Kent as inputs. Peak flow estimates resulting
from the MGSFlood model were unrealistically high, with initial 2D model results indicating overtopping of
Talbot Road South during the 2-year peak flow event. This is likely due to the coarseness of the model
constructed, which represents the entire watershed as a single unit rather than dividing it into
sub-watersheds and directly modeling the existing stormwater infrastructure.
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A study conducted by RW Beck (R.W. Beck 1997) includes descriptions of hydrology for the adjacent
Springbrook Creek basin, which Panther Creek is a tributary. The study lists peak flow inputs to Springbrook
Creek from Panther Creek corresponding to the 2- and 100-year peak flow events on Springbrook Creek.
Neither the 2- and 100-year events on Panther Creek, nor the peaks, necessarily coincide with those on
Springbrook Creek. The flows for Panther Creek correspond to a location just upstream of a point along
SR 167 approximately 1.5 miles downstream of the project crossing on Panther Creek. Most of this
downstream reach of Panther Creek flows within a wetland running parallel to SR 167 along its east side,
and there are several piped locations conveying flow from the wetland to the west below SR 167. The
effects of these piped connections to the wetland are not well understood. Despite these facts, the flows
reported seem reasonable for the Panther Creek crossing location at Talbot Road South and they were
identified in the study using detailed hydrologic modeling and therefore in our judgement represent the
best available hydrologic data and serve as the basis for our analysis for this project.
TABLE 1: PEAK FLOW HYDROLOGY SUMMARY
AVERAGE RECURRENCE
INTERVAL PEAK FLOW EVENT
(YEAR)
BASIN TRANSFER FROM
MOLASSES CREEK (CFS)
USGS
REGRESSION
(CFS)
MGS FLOOD, 15-MIN
TIMESTEP (CFS)
SPRINGBROOK BASIN
STUDY (CFS)A
2 37 28 179 67
100 90 57 500 197
500 111 127 638 2512
Projected 2080 1003 107 68 597 235
Notes:
1. Bolded flows denote those used for analysis and design
2. Extrapolated from data using a logarithmic curve fit.
3. Estimated using WDFW climate change tool. Simulated only for proposed design condition.
cfs = cubic feet per second
2.2 SUMMARY OF GEOTECHNICAL INVESTIGATION
GeoEngineers completed a geotechnical investigation of the site, which is documented in a Preliminary
Geotechnical Letter (GeoEngineers 2023b). The geotechnical investigation included installing three borings
along the eastern edge of Talbot Road South. Boring B-1 was installed approximately 75 feet north of the
existing culvert to a depth of approximately 30 feet below the ground surface. Boring B-2 was installed
approximately 10 feet north of the existing culvert to a depth of approximately 25 feet below the ground
surface where it met refusal. Boring B-3 was installed approximately 65 feet south of the existing culvert to
a depth of approximately 35 feet below the ground surface. For reference, the road surface elevation varies
from approximately 96 feet at the north boring to approximately 98 feet at the south boring and the culvert
invert elevation at the road centerline is approximately 67 feet.
Figure 3 in the Preliminary Geotechnical Letter is a cross section along Talbot Road South depicting the
materials encountered in the borings. Subsurface soils were identified as up to approximately 20 to 25 feet
of various types of poor-quality fill (loose clayey silty sands) over a layer of dense glacial till approximately
10 to 15 feet thick, over Renton formation bedrock (siltstone/sandstone). The fill layer extends the deepest
at Boring B-2, which met refusal at approximately Elevation 70 feet, possibly hitting a concrete object,
possibly the foundation of a wood trestle bridge that previously existed at the site based on old King County
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plans recovered by the City (King County 1943). The fill layer likely extends to the north and south to the
historic valley walls.
Boring B-2 did not reach the bottom of the fill layer; no glacial till or bedrock was encountered. Therefore,
it is uncertain whether glacial till and/or bedrock are present in the immediate vicinity of the existing culvert.
2.3 INFRASTRUCTURE
2.3.1 Road
Panther Creek crosses from east to west under Talbot Road South, which is a two-lane road aligned north
and south. At the roadway centerline, the depth of fill over the top of the culvert is approximately 26 feet.
The bridge design memo (KPFF 2025) describes the existing roadway and proposed bridge in more detail.
2.3.2 Utilities
Utilities at the site include:
■ Two storm drains discharge to the area upstream of and near to the project crossing (City of Renton).
■ A 12-inch-diameter water main (City of Renton)
■ An 18-inch-diameter sanitary sewer main (King County)
■ 2-inch and a 16-inch natural gas lines (Puget Sound Energy)
■ Multiple overhead power and communication lines (Multiple owners).
The bridge design report (KPFF 2025) describes the existing and proposed utilities in more detail.
3.0 Channel Hydraulics
GeoEngineers developed HEC-RAS version 6.4.1 (USACE 2023) two-dimensional (2D) models for both
existing and proposed conditions geometries for the peak flows shown in Table 1. We modeled the existing
crossing structure as a culvert to account for pressure flow. The proposed channel below the proposed
bridge was modeled within the 2D mesh due to open-channel flow conditions. Appendix C, Hydraulic
Modeling Summary Results contains figures showing select results.
The proposed channel and bridge structure at the Talbot Road South crossing eliminates the backwater
caused by the existing undersized culvert during flood flows. The following table (Table 2) shows important
hydraulic results for the proposed channel for a section corresponding to stream centerline station 2+80.9
at the intersection with the proposed bridge structure centerline.
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TABLE 2. PROPOSED CHANNEL HYDRAULICS AT BRIDGE CENTERLINE
AVERAGE RECURRENCE
INTERVAL PEAK FLOW
EVENT (YEAR)
MAXIMUM CHANNEL
DEPTH (FEET)
WATER SURFACE
ELEVATION (FEET,
NAVD88)
AVERAGE MAIN CHANNEL
VELOCITY (FPS)
FLOW TOP WIDTH
(FEET)
2 1.2 67.6 6.2 15.4
100 2.0 68.3 8.9 20.5
500 2.2 68.5 9.6 21.4
Projected 2080 100 2.1 68.4 9.4 20.5
Notes:
fps – feet per second
4.0 Stream Design
This section describes identification of preliminary criteria for design of the stream channel and crossing
structure. The crossing site may have a remnant natural stream bed of dense glacial till and/or bedrock;
however, the horizontal and vertical extent of this material is not known and will be fully discovered only
during project construction following excavation of the road embankment. The 10 percent design elements
presented below assume that no dense till or bedrock is present, or that it is removed and replaced with
alluvium material.
4.1 STREAM CHANNEL
The crossing under Talbot Road South must meet requirements of the Water Crossing Design Guidelines
(WCDG) (Barnard et al. 2013). General conformance to the Washington State Department of Transportation
(WSDOT) Hydraulics Manual (HM) (WSDOT 2024), while not mandatory, is recommended. Stream design
drawings at the 10 percent level are provided in Appendix D, 10 Percent Design Stream Plans.
4.1.1 Alignment
Drawing Sheet ST-2 in Appendix D provides the proposed creek alignment and grading. The proposed creek
alignment is rotated clockwise to be perpendicular to Talbot Road South. Upstream of the culvert, the
proposed alignment shifts the creek to the south to remove the slight overshoot in the existing alignment.
The overshoot is undesirable as it prevents flow from smoothly entering the culvert and could contribute to
further bank erosion and channel migration to the north, making the overshoot worse with time. The area
to the north of the creek gained by shifting the creek to the south will be used to install bank protection
measures to mitigate potential channel migration. With the shift of the creek to the south, future
maintenance is anticipated to be easier and less costly as compared to the existing alignment.
Downstream of the crossing, the proposed alignment moves the creek slightly north to reduce the potential
for further erosion of the undercut left bank, which shifts the creek into the wetland area on the right bank.
4.1.2 Profile
Drawing ST-3 in Appendix D provides the proposed stream profile. The existing reach average slope in the
vicinity of the crossing is 3.9 percent as identified from the channel survey limits. The WCDG
(Barnard et al. 2013) allow the restored profile to have a slope up to 1.25 times the existing reach average
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slope, equal to 4.9 percent. The proposed profile has a slope of 4.6 percent. The scour pool downstream
of the existing culvert will be filled. We estimated the channel gradient through the reference reach to be
4.4 percent using available Light Detection and Ranging (lidar) data.
4.1.3 Channel Section
Drawing ST-3 in Appendix D provides the proposed typical channel section. The proposed bankfull channel
has a width of 9.4 feet and a depth of 1 foot. The stream channel will be meandered within a broader zone
of floodplain benches that is 18 feet wide through the crossing. The floodplain benches will be engaged
during the 2-year flood event and greater flows. At the 100-year flood event, hydraulic modeling estimates
a flow depth of 2.0 feet above the channel thalweg, and a flow width of 20.5 feet. As such, the flow depth
at the outer edges of the floodplain benches will be 0.9 feet.
4.1.4 Stream Substrate
The proposed thickness of the streambed substrate layer is 3 feet. The streambed substrate width within
the crossing is 18 feet to cover the width of the stream zone and accommodate stream meanders.
A specific stream substrate gradation has not been developed at this stage of design. The streambed
substrate is anticipated to be a mix of fines, sand, gravel and cobbles similar in gradation to substrate
noted in the reference reach. If alluvium of appropriate gradation is encountered after removal of the
roadway embankment, it would be used as the new streambed substrate instead of replacing it with import
material.
The presence of dense glacial till or bedrock in the stream reach where the existing road embankment will
be removed is suspected due to encountering these materials in Borings B-1 and B-3; however, it was not
confirmed since Boring B-2 was obstructed and did not reach the elevation of the proposed streambed
thalweg. Although bedrock may have been the natural pre-disturbance condition in some portions of the
stream bed, we anticipate that current regulatory requirements for crossing replacement will require fish
passage parameters to be achieved, precluding the option of leaving a bedrock stream bed. If dense till or
bedrock is present, its surface elevation and characteristics are uncertain. Alluvial material is potentially
unstable over a hard smooth surface such as dense glacial till or bedrock. Therefore, the 10 percent design
stage assumption is that if the till/bedrock is present and requires removal, then it would need to be
removed to the preliminary scour depth of 3 feet, plus an additional 2 feet so that residual stream substrate
would remain after occurrence of scour to the total scour depth. Therefore, till/bedrock would need to be
removed to a depth of 5 feet below the proposed thalweg. This would aid in maintaining favorable fish
passage conditions, which may otherwise be compromised if till/bedrock were exposed through the
crossing. Exposure of bedrock through the crossing could possibly result in inadequate water depth during
times of low flow and/or a vertical drop as a result of scour where bedrock transitions to other substrate
material.
4.1.5 Temporary Stream Bypass
Drawing ST-4 in Appendix D provides the Temporary Stream Bypass Plan at a 10 percent conceptual level.
4.1.6 Habitat Features
Potential features to be developed during future design phases include stream channel meanders within
the 20-foot-wide stream zone, large wood material, native plantings and other elements to be identified.
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Stream meander bars are limited to streams with slopes less than 3 to 4 percent, and, therefore, are not
suitable for this project.
4.1.6.1 CHANNEL MEANDERS
The proposed 9.4-foot-wide stream bankfull channel will be meandered within the 20-foot-wide stream
zone of floodplain benches. Within the proposed 9.4-foot-wide bankfull channel, a low flow channel will be
created to connect large wood material (LWM) and other habitat features.
4.1.6.2 LARGE WOOD MATERIAL
Outside the limits of the crossing structure, LWM will be place in the restored stream channel to improve
aquatic habitat quality and diversity. LWM details will be developed at the 30 percent design state. LWM
will be designed to promote the target channel morphology and follow standard engineering practices for
placement of LWM in stream. Due to the small stream size (bankfull width less than 10 feet), wood density
are anticipated to be less than the 75th percentile criteria in Fox and Bolton (Fox and Bolton 2007).
The WSDOT HM discourages placement of LWM directly under bridges or adjacent to bridge foundations.
Upstream of the bridge, LWM placement will focus on enhancing channel complexity while preventing
channel migration to maintain appropriate alignment of the stream between the bridge abutments.
Downstream of the bridge, LWM placement with focus on enhancing channel complexity to prevent channel
migration into the right bank wetland area.
Both upstream and downstream of the crossing, LWM placement will also be used to enhance bank stability
considering inflows from the various storm drainpipes in the area. Cobbles and boulders may be added to
provide splash pads for resisting erosion from storm drainpipe discharges. Some storm drains have
substantial scour holes and vertical drops and may require placement of riprap or other more substantial
erosion control measures.
It is anticipated the LWM would be ballasted with a combination of approaches, including using larger wood
with a portion of the wood located above the 100-year flood level, wood embedment in stream substrate
and rock ballasting. If dense glacial till or bedrock is present, LWM structure types and ballast/anchorage
details may need to be revised.
Drawing ST-5 in Appendix D provides typical details for potential LWM structures.
4.1.6.3 WETLAND RESTORATION
The existing wetland on the right stream bank downstream of the culvert has an area of 1,356 square feet.
Approximately half the wetland would be impacted by excavation of the proposed stream channel along its
new alignment. The proposed stream thalweg elevation is approximately 1.7 feet higher along the wetland
edge than the existing thalweg. Lowering the proposed stream thalweg along the edge of the wetland was
evaluated and identified to be infeasible because it would increase the overall length of stream impact by
several hundred feet. Therefore, a portion of the wetland surface may need to be raised in elevation with
suitable topsoil and replanted with native wetland species. Fill of the existing large scour hole also provides
an opportunity for wetland restoration/creation, which is illustrated conceptually on drawing sheet LS-1
(Appendix D). Additional details will be developed at a future design stage.
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4.2 CROSSING STRUCTURE CONSIDERATIONS
The following elements were developed, assuming the crossing structure will be a bridge with proposed
span and height substantially exceeding the minimum values required for fish passage per the WCDG. If a
smaller bridge or utility bridge is proposed, the recommendations noted below would need to be confirmed
or revised.
4.2.1 Crossing Structure Minimum Width and Vertical Clearance
The recommended minimum hydraulic opening (MHO) for a replacement culvert structure, also known as
the culvert interior width, would be proposed at 18 feet based on hydraulic modeling analyses. The
proposed bridge span of approximately 110 feet is substantially greater than this value.
Freeboard must provide a minimum of 2 feet vertical clearance above the 100-year flood elevation. The
estimated 100-year water surface elevation based on hydraulic modelling at the road centerline is
approximately 68.4 feet, based on a thalweg elevation of 66.3 feet, and a projected 2080 future 100-year
flood flow depth of 2.1 feet (see Table 2). Therefore, all portions of the crossing structure (including bridge
and utility supports) within the limits of the MHO must be located at elevation 70.4 feet or higher. If possible,
it is recommended to providing 6 or 8 feet of clearance above the thalweg to ease future maintenance and
facilitate wildlife passage.
4.2.2 Crossing Structure Scour
Preliminary scour recommendations are provided to aid the bridge design per the WSDOT HM
(WSDOT 2024). Total scour is determined by the sum of various scour components: channel migration,
contraction scour, bend scour, local scour and wall scour, plus long-term channel degradation. The WSDOT
HM requires total scour be assessed for flows up to the scour design flood (year 2080 estimated 100-year
flood flow) and scour check flood (current 500-year flood flow). WSDOT requires that total scour be taken
as the actual estimated total scour, or a minimum of 3 feet, whichever is greater.
The potential for channel migration depends on the geologic conditions at the site, which are not currently
known. Mapped geology in this region indicates that dense glacial till and/or bedrock may be present below
the existing culvert elevation and flanking the current stream bed along the valley walls (see Preliminary
Geotechnical Design Letter dated November 2, 2023). The stream could potentially migrate laterally within
the limits of the valley alluvium material, but the risk of further channel migration into zones of dense till or
bedrock is low.
The risk of migration across the available valley bottom, specifically upstream of the existing culvert inlet,
cannot be classified as low. The creek is generally confined with little floodplain throughout most of the
observed reach with the exception of the left bank floodplain just upstream of the existing culvert inlet. The
valley bottom width at this location is approximately 60 feet compared to that of the reference reach where
the valley bottom width measures approximately 25 feet wide. This left bank floodplain is up to 40 feet
wide and extends approximately 90 longitudinal feet. The limited available floodplain and ravine
confinement throughout most of the observed reach reduces the opportunity for alternate flow paths and
avulsion, which is not a dominant channel process in this system; however, as noted above, the area
upstream of the existing culvert inlet is less confined and therefore has increased potential for lateral
migration.
City of Renton | May 30, 2025 Page 10
File No. 0693-093-00
The proposed structure is sufficiently wide that it does not interact directly with the design or check floods;
therefore, contraction scour and wall scour is negligible. Local scour is also minimal as there are no
obstructions or bends.
Based on the above preliminary analyses, the recommended total scour depth is 3 feet below the stream
thalweg. This result is applicable if the substrate exposed by removal of the road embankment is alluvium
with a gradation similar to the existing stream substrate.
If the substrate exposed by removal of the road embankment is substantially different, such as dense
glacial till or bedrock, then scour recommendations may change.
4.2.3 Crossing Structure Foundation
The bridge foundation is described in the bridge design report (KPFF 2025). The proposed thalweg elevation
for Panther Creek at the Talbot Road South centerline is 66.2 feet. The preliminary estimate for the total
scour depth is 3 feet.
4.3 PERMITTING
Permitting for stream-related work would require preparation of a Joint Aquatic Resources Permit
Application (JARPA) with the goal to obtain a Hydraulic Project Approval (HPA) from WDFW and a
Section 404 Clean Water Act Nationwide Permit from the U.S Army Corps of Engineers (USACE). As this is
a fish passage restoration project anticipated to qualify for a Fish Habitat Enhancement (FHE) HPA, the
project would be exempt from local permits such as from the City. Obtaining these permits will require
coordination with Native American tribes including the Muckleshoot Indian Tribe.
The project site contains City designated critical areas for erosion, landslides and steep slopes. Additional
geotechnical input during future design phases is anticipated.
The project is not within a Zone A or Zone AE 100-year floodplain (Appendix B); therefore, floodplain
development permits are not anticipated to be required.
4.4 CONSTRUCTION
It is anticipated that stream work would be bid and constructed as part of the larger bridge project. The City
would coordinate bidding and be the construction administrator. Acquisition of property and temporary
construction easements would be completed by the City.
Stream related work is anticipated to be mostly covered by WSDOT standard specifications and standard
bid items. Stream related work is anticipated to be completed with traditional excavation and construction
equipment and methods. Stream construction will require temporary stream bypass with appropriate fish
exclusion work practices and equipment. Stream work would need to be completed within the allowed in-
water work window specified in the HPA permit (estimated to be August 1 to 31). It is anticipated that
stream work could be completed during one summer construction season.
City of Renton | May 30, 2025 Page 11
File No. 0693-093-00
5.0 Estimate of Construction Cost
The conceptual level engineer’s estimate of probable costs for the stream design elements is unchanged
since the alternatives analysis estimate, which is included as Appendix E, 10 Percent Design Opinion of
Probable Construction Cost. Key assumptions and data gaps related to the cost estimates are noted below:
■ Temporary stream bypass can be implemented using a gravity system without pumping.
■ Streambed substrate is anticipated to be a mix of fines, sand, gravel and cobble. The cost estimate
assumes replacement of native material with imported material for about half of the streambed
material shown in the typical section on Sheet ST-3 (See Appendix D).
■ Costs for removal of dense glacial till or bedrock are not included.
■ LWM material will be incorporated into the stream design as described in Section 4.1.6.2. Design and
costs for LWM assume installation in alluvium material.
■ Minor impacts to the wetland downstream of the crossing are anticipated to be accommodated within
the permitting process anticipated for the project, without additional mitigation.
6.0 Stream Related Data Gaps
The following stream related data gaps have been identified:
■ The presence of bedrock at approximately the existing stream thalweg elevation, particularly in the
existing roadway embankment, is suggested by the geotechnical investigation but could not be
confirmed due to the obstruction of Boring B-2. If dense glacial till is present, design changes could be
required for excavation of the creek subgrade, import of streambed material, anchoring of LWM and
other work elements, impacting the project cost. Completing one or more additional geotechnical
borings could improve understanding of the presence, elevation and characteristics of dense
till/bedrock for the proposed streambed at the boring location(s). This information would clarify the
work to be completed during construction and reduce the risk of changes to the project work, cost and
schedule during construction. Alternatively, flexibility during construction could adapt to the conditions
encountered. We recommend completing two designs of the creek, a design considering no bedrock
and an alternate design considering an assumed extent of bedrock. The two designs could be bid as a
base bid and a bid alternate.
7.0 References
Barnard, R., Johnson, J., Brooks, P., Bates, K., Heiner, B., Klavas, J., Powers, P. 2013. Water Crossing Design
Guidelines. Washington Department of Fish and Wildlife. Olympia, WA.
City of Renton. 2023. City of Renton COR MAPS System, 2021 Digital Elevation Model Layer, Accessed
November 8, 2023)
Federal Emergency Management Agency (FEMA). 2023. National Flood Hazard Layer FIRMette, Panel
53033C0979G, effective 8/19/2020. Exported on November 7, 2023.
City of Renton | May 30, 2025 Page 12
File No. 0693-093-00
Fox, M. and Bolton. 2007. A Regional and Geomorphic Reference for Quantities and Volumes of Instream
Wood in Unmanaged Forested Basins of Washington State. North American Journal of Fisheries
Management, 27: 342-359.
GeoEngineers, Inc. (GeoEngineers). 2023a. Critical Areas Assessment, Panther Creek at Talbot Rd S Culvert
Replacement Project. Prepared for City of Renton, October 23, 2023. GEI File No. 0693-093-00.
GeoEngineers, Inc. (Geoengineers). 2023b. Preliminary Geotechnical Design Letter, Panther Creek Culvert
Replacement Project, Renton WA. Prepared for City of Renton, October 23, 2023. GEI File No.
0693-093-00.
King County. 2023. Hydrologic Information Center. Retrieved from Kingcounty.gov:
https://green2.kingcounty.gov/hydrology/DataDownload.aspx?G_ID=97&Parameter=Stream%20
Flow
King County. 1943. John Langston Rd Revn for Fill Bridge No. 80c. King County Sec. Road Proj. No. 49,
Commissioner’s District 2, Approved Feb 19, 1934.
KPFF Consulting Engineers (KPFF). 2025. Panther Creek 10% Bridge Design - Basis of Design.
Memorandum submitted to City of Renton, February 12, 2025.
Mullineaux, D. 1965. Geologic map of the Auburn quadrangle, King and Pierce Counties, WA. U.S. Geologic
Survey, Geologic Quadrangle Map GQ-406.
R.W. Beck. 1997. East Side Green River Watershed Project, Environmental. Prepared for City of Renton,
September 1997.
U.S. Army Corps of Engineers (USACE). 2023. Hydrologic Engineering Center – River Analysis System (HEC-
RAS). Available at https://www.hec.usace.army.mil/software/hec-ras/.
Washington Department of Fish and Wildlife (WDFW). 2022. Level A Culvert Assessment Report, Site ID
931933, Panther Creek. February 16.
Washington State Department of Transportation (WSDOT). 2024. Hydraulics Manual. Design Office,
Engineering and Regional Operations Division, Publication Number M23-03.10.
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Coordinate System: NAD 1983 StatePlane Washington North FIPS 4601 Feet
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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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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. Geo Engineers 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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Figure 2 a:---------------------------------------------------------------------------------------------------------------------------------------------------·
Appendices
Appendix A
Stream Field Report
☐ THIS FIELD REPORT IS PRELIMINARY
A preliminary report is provided solely as evidence that field observation was performed. Observations
and/or conclusions and/or recommendations conveyed in the final report may vary from and shall take
precedence over those indicated in a preliminary report.
FIELD REPRESENTATIVE DATE
Chelsey Gohr, LG 8/2/23
Evan Deal, PE 8/2/23
David Conlin, PWS 7/20/23
☒ THIS FIELD REPORT IS FINAL
A final report is an instrument of professional service. Any conclusions drawn from this report should be
discussed with and evaluated by the professional involved.
REVIEWED BY DATE
Ken Fellows, PE 8/7/23
Dan Eggers, PE 8/13/23
This report presents opinions formed as a result of our observation of activities relating to our services only. We rely on the contractor to comply with the plans and specification throughout the duration of the project irrespective of
the presence of our representative. Our work does not include supervision or direction of the work of others. Our firm will not be responsible for job or site safety of others on this project. 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.
Attachments: Figures 1 through 15
Distribution:
Field Report File Number:
0693-093-00
1101 Fawcett Ave, Suite 200
Tacoma, WA 98402
253.383.4940
Project:
City of Renton, Panther Creek Culvert Replacement
Date(s):
June 28, 2023,
July 31, 2023
Owner:
City of Renton
Time of Arrival:
9:00 AM
Report Number:
FR-01
Prepared by:
Chelsey Gohr, LG, Peter Savchik,
Bea Renaud, David Conlin, PWS,
and Evan Deal, PE
Location:
Panther Creek at Talbot Road South
Renton, Washington
Time of Departure:
varies
Page:
1 of 16
Purpose of visit:
Stream Reconnaissance
Weather:
Sunny, dry
Travel Time:
varies
Permit Number:
n/a
Upon arrival to the site, I assessed personal safety hazards: Yes or Referred to Site Safety Plan and Safety Tailgate if applicable
Safety Hazards Were Addressed by : Staying Alert to Traffic Slip, Trip and Falls
0BINTRODUCTION
Washington Department of Fish and Wildlife (WDFW) has identified the crossing of Panther Creek under Talbot
Road South (WDFW Site ID: 931933) as a total fish passage barrier due to water surface drop (WDFW 2022)
(Figure 1 and Figure 2). The City of Renton has also identified the existing crossing structure at this location as
failing, presenting a risk to traveling public. GeoEngineers, Inc. (GeoEngineers) is working under contract to the City
of Renton to complete a hydraulic design for replacement of the deteriorated crossing structure at this location that
meets fish passage criteria and reduces risk to the public. This field report documents our observations of the
existing geomorphic, biological, and hydraulic conditions of Panther Creek in the vicinity of the existing crossing.
Fieldwork was completed on June 28 and July 31, 2023, including general site observations, assessment of stream
conditions, identification of a reference reach, and collecting bankfull width measurements and Wolman pebble
count data. The GeoEngineers’ field team (Table 1) assessed the crossing structure inlet and outlet, the upstream
channel within approximately 230 feet upstream and from approximately 350 to 450 feet upstream of the culvert
inlet, and the downstream reach within approximately 200 feet downstream from the culvert outlet.
File No. 0693-093-00
August 14, 2023
Page 2
TABLE 1. FIELD TEAM
Name Role
Evan Deal, PE River Engineer
Peter Savchik Staff River Engineer
Chelsey Gohr, LG Staff Fluvial Geomorphologist
David Conlin, PWS Senior Ecologist
Bea Renaud Staff Biologist
1BGENERAL SITE DESCRIPTION
The project site is located in the City of Renton, Washington, in King County. The subject crossing is located where
Panther Creek crosses Talbot Road South, just north of Valley Medical Center. The City of Renton plans to replace
the culvert passing underneath Talbot Road South, as it is deteriorated and therefore at risk of failure, as well as
being a barrier to fish passage. Talbot Road South, at this location, provides hospital access from the north.
The project crossing of Panther Creek is located along the gradual transition from steeper sloped terrain near the
stream headwaters on Benson Hill to shallower sloped terrain in the valley bottom associated with the Green River
floodplain and several tributaries to the Green River. Panther Creek originates at Panther Lake approximately
1.75 miles to the southeast and flows generally northwest or west through a confined ravine and through the project
crossing. Approximately 850 feet downstream of the project crossing, the confined ravine topography transitions to
a wider valley bottom in the greater Green River Valley. Through the Green River Valley, Panther Creek flows north
for approximately one-half mile through several low-gradient wetland complexes before turning west under SR 167.
The remainder of Panther Creek is generally ditched through an industrial and commercial area, where it flows into
Springbrook Creek approximately 0.85 miles downstream of the SR 167 crossing, and then into the Black River
and Green/Duwamish River, eventually flowing into the Puget Sound at the Duwamish waterway in Seattle.
Downstream of the project crossing, there are no other structures currently considered by WDFW to be barriers to
fish passage (WDFW 2023).
The ravine in which the project site is located is mapped by Mullineaux (1965) as the Renton Formation and is
characterized by Arkosic sandstone, mudstone, and shale. All other areas surrounding the project reach, including
the reference reach, are mapped as glacial till, consisting of compact, unsorted sand, silt, clay, and gravel.
2BREFERENCE REACH
A reference reach was established during the July 31st site visit starting approximately 350 feet upstream of the
project crossing where longitudinal channel slopes are similar to design slope targets. The field team then
progressed upstream to an area assumed to be out of the area of influence of the confluence of unnamed tributary
(UNT) to Panther Creek and Panther Creek (located at approximately 500 feet upstream of the crossing inlet) to
mark the upstream most end of the reference reach approximately 450 feet upstream of the project crossing. See
Figure 3 and Figure 4 for upstream and downstream reference conditions.
The approximately 100-foot-long reference reach is a single thread channel located within a meander bend with
the apex oriented along the right bank. The reach has an average slope of 4.4 percent (Washington State
Department of Natural Resources, 2021) and exhibits a step-pool bedform. An approximate 35-foot-long portion of
the reference reach appears more as a step-riffle morphology as pools are very shallow. Water surface drops off
several inches occur across these steps (Figure 5). Pools ranged from approximately 2 to 5 feet long with a
File No. 0693-093-00
August 14, 2023
Page 3
maximum depth measured of 5-inches deep. Streambed material in the reference reach consists of small to
medium-sized cobbles with coarse gravels and occasional small boulders. Fine to coarse sands were observed
along channel bank toes with a fine to coarse gravel armor, or within undercut pools.
On the inside (left bank) of the meander bend, the banks were up to 6 feet high. Undercut banks were common
and multiple areas of bank failure were observed as bare (lack of vegetation), vertical banks. On the right bank, or
outside of the meander bend, channel banks ranged from a few inches to up to 1.5 feet high. Floodplains and
discontinuous benches were observed along the right bank throughout the reference reach with the exception of
the downstream end of the reference reach where the right bank rises up to 4 feet above the channel and the left
bank becomes accessible to higher flows (Figure 6).
3BSEDIMENT SAMPLING
GeoEngineers completed four Wolman pebble counts (PCs): three upstream and one downstream of the project
crossing (Table 3). One pebble count (PC1) is located within the reference reach. The field team collected each
pebble count across 10 separate linear transects perpendicular to flow through a riffle and within the bankfull
width. The largest naturally occurring clasts in the system were small to medium boulder sized.
TABLE 2: WOLMAN PEBBLE COUNT DATA
Pebble Count PC1 Upstream
(Reference Reach)
(in)
PC2 Upstream
(in)
PC3 Upstream*
(in)
PC4 Downstream
(in)
Diameter
Percentile
D16 0.6 0.4 1.1 0.5
D50 2.3 1.5 2.9 1.6
D84 5.8 4.2 4.9 4.3
D95 8.5 9.6 6.8 6.0
*Note – Pebble count data collected in a location with a bankfull width measurement excluded from the design average BFW calculation
4BBANKFULL WIDTH
The field team recorded nine bankfull width measurements (BFWs; Table 3); six upstream of the crossing and three
downstream. Three of the upstream measurements were taken within the reference reach. Four of the bankfull
measurements coincide with the locations of pebble counts collected at the site. Table 3 presents the bankfull
width measurements and locations. The two bankfull width measurements upstream of and nearest to the crossing
inlet were not included in the design bankfull width calculation. These measurements were not considered to be
representative of the natural stream condition because they are likely within a depositional reach caused by the
backwater influence of the existing, undersized crossing structure expected to occur during flood flows.
File No. 0693-093-00
August 14, 2023
Page 4
TABLE 3: GEOENGINEERS BANKFULL WIDTH MEASUREMENTS
Approximate Distance (feet) Upstream or
Downstream from Crossing Inlet or Outlet
Respectively
Bankfull Width (feet) Used in Design BFW Average?
40 (Upstream) 17.5 No
70 (Upstream, at PC3) 14 No
215 (Upstream, at PC2) 8.8 Yes
350 (Upstream within reference reach; at PC1) 9 Yes
405 (Upstream within reference reach 9.8 Yes
450 (Upstream within reference reach) 8.7 Yes
75 (Downstream, downstream of pool) 14.3 Yes
172 (Downstream) 8.6 Yes
182 (Downstream, at PC4) 7 Yes
Design Average 9.5 -
5BOBSERVATIONS
8BProject Crossing
The project crossing is comprised of a 32-inch diameter fiberglass reinforced corrugated steel pipe with a slope of
4.11 percent (WDFW, 2022). There is a significant amount of road fill above the culvert; about 34 feet at the
downstream end and 20 feet at the upstream end. The upstream end of the culvert is framed by a concrete headwall
and wingwall, and considerable structural damage to the pipe due to gravel wear along its invert was observed
within the first several feet of pipe length at the inlet (Figure 1). This damage is likely the result of wear from
sediment transported through the pipe. A channel-spanning log was observed within the channel at the inlet,
creating an approximately 1.5-foot drop into the inlet and accumulating streambed sediment upstream.
Downstream, the elevated crossing outlet has produced a 3.9-foot drop, as measured at the time of the field
reconnaissance, from the culvert exit into a large scour pool below (Figure 2). The outlet scour pool had a maximum
water depth of approximately 4 feet, as measured at the time of the field reconnaissance.
In addition to the project culvert, two additional flow inputs were observed upstream of the crossing: stormwater
road runoff from Talbot Road South was observed entering Panther Creek at the left bank immediately upstream
of the project culvert inlet, and a municipal stormwater pipe was observed discharging to Panther Creek from the
right bank approximately 95 feet upstream of the crossing inlet.
9BLarge Woody Material
In the approximately 230-foot reach observed upstream of the project crossing, large woody material (LWM) is
typically lacking, with several notable exceptions. At the upstream end of the observed reach (230 feet upstream
of the inlet), woody material pieces consisting of fallen branches and small mobile woody material were present
and contributed to the development of diverse micro habitats and in-channel complexity. Approximately 180 feet
upstream of the crossing, a roughly 2-foot diameter channel spanning log covered by a thick layer of vines (English
ivy, Hedera helix) was observed. The log rests approximately 3 feet above the channel on both the right and left
banks and provides cover and shade over the channel. Just before the crossing, there is a large channel spanning
log embedded into the channel bottom and wedged between the concrete wingwalls and/or riprap armor material,
creating an approximately 1.5-foot drop into the culvert inlet (Figure 7). Several pieces of large, milled lumber line
File No. 0693-093-00
August 14, 2023
Page 5
the right bank just upstream of the inlet and appear to be placed material, forming a bank armoring structure.
These pieces appear to have little interaction with the channel except for at higher flows. Approximately 35 feet
upstream of the crossing there is a collection of woody material concentrated on the right of the channel, followed
by a scour pool (Figure 8).
Downstream of the culvert, there are a number of pieces of LWM interacting with flow. Directly below the culvert
outlet several LWM pieces were observed within the scour pool. Downstream from the scour pool, several single
logs were observed interacting with flow, either entering obliquely from the bank or spanning the channel, creating
steps and pools (Figure 9).
No LWM was observed within the reference reach. Portions of the reference reach included branches up to
approximately 0.5 inches in diameter hanging into the channel (Figure 3). Near the upstream end of the reference
reach there were fallen branches of approximately 1.0 to 2.0 inches in diameter racked up near an approximately
36-inch diameter boulder. Combined, these branches spanned the channel reinforcing the step adjacent to the
boulder.
10BGeomorphology
Panther Creek flows as a sinuous, single-thread channel with varying slopes, bedforms and cross-sectional
characteristics. Average reach slopes range from about 1.9 to 4.4 percent. A reach-based longitudinal profile is
presented in Figure 11.
Upstream of Project Crossing
Panther Creek flows slightly sinuous to sinuous and is confined within a ravine. Between the crossing inlet and the
confluence with the municipal stormwater pipe (approximately the first 100 feet upstream of the inlet), the channel
widens to nearly double the size of the uppermost observed reaches. Bed material is predominantly cobbles, small
boulders, and gravel and form steps within the channel down to the inlet. Just upstream of the confluence with the
municipal stormwater pipe (approximately 95 feet upstream of inlet) channel banks are nearly vertical and range
from 1.0 to 2.5 feet high and channel widths were observed to be approximately 7 to 9 feet. Minor toe erosion was
observed throughout, and banks were heavily vegetated to the channel bank toe. Channel morphology is pool-riffle.
Both riffles and pools were generally long running with pool depths no more than a few inches deep. Narrow, lateral
gravel and sand bars were also observed. Throughout the entire upstream reach observed, floodplains are generally
more accessible along the left bank.
Sediment is predominantly very coarse gravel with cobbles and occasional boulders and a few angular concrete
pieces of riprap were observed. Most of the boulder-sized material is covered with moss and not likely mobile except
at very high flows. Few pieces of large wood interact with flow as are observed hanging over the channel with
branches in the flow racking minor small mobile woody material.
See Reference Reach section above for detailed geomorphic assessment of the reference reach.
Downstream of Project Crossing
At the downstream outlet, there is a large scour pool that reaches depths of approximately 4 feet. Immediately
downstream of the pool, there is an accumulation of small cobbles and gravel with sand (Figure 12). The left bank
coincides with the left valley wall, and exposed sandstone and mudstone is observed (Figure 14). The right bank
offers backwater habitat at high flows that is most accessible approximately 27 feet downstream of the pool. The
200 feet of observed reach downstream of the culvert is pool-riffle morphology, with riffles on average measuring
File No. 0693-093-00
August 14, 2023
Page 6
twice as long as pools (Figure 13). Bedform is mainly riffle, with some sections that are glide. Pool depths ranged
from just a few inches to up to 1.1 feet deep. The deeper pools were observed just downstream of log pieces.
For almost the entire reach that was observed, the left valley wall is confined with no accessible floodplain;
discontinuous benches are approximately 2 feet above channel bed, but as high as 4 feet with vertical banks. In
general, the right banks are sloped back and are no higher than 1.5 feet. Minor undercutting and toe erosion were
observed. Lateral spanning channel bars consisted of coarse gravels and cobbles and a few sand deposits were
observed. As the slope declines (1.9 percent slope) moving downstream, the left bank floodplain becomes
accessible.
11BAquatic Habitat
Panther Creek appears to provide decent habitat for fish, particularly upstream of the project crossing, which has
more intact riparian forest vegetation (e.g., Figure 4). Flow is perennial and sufficient to support all life stages of
salmon or trout year-round. The primary physical limiting factors for fish utilization in the project vicinity are
anticipated to be: (a) limited riparian cover and closure in the reach immediately downstream (Figure 15), and
(b) the total fish barrier presented by the subject culvert. Water quality may also be an issue, particularly in light of
the stormwater discharge to the creek as well as the large outfall from a stormwater detention pond. Panther Creek
is 303(d) listed for Benthic Index of Biotic Integrity, indicating degraded water quality. Panther Creek is also listed
as Category 4A for temperature and there is a total maximum daily load (TMDL) in place for the Green River
Watershed. Stormwater management from urban runoff as well as lack of riparian shade may contribute to elevated
temperatures in Panther Creek.
There are no fish barriers present within the system downstream of the project crossing. Anadromous fish may
access Panther Creek up to the project crossing, but the subject culvert is believed to be a total fish barrier (WDFW
2022). Resident fish populations may occur both upstream and downstream of the crossing, and would also benefit
from crossing replacement. The stream gradient is typically within the range for fish utilization.
Substrate conditions throughout the reaches observed appeared generally appropriate for use by salmonids.
Embeddedness is low and the distribution of sediment sizes, including boulders, cobbles, gravel, and sand appears
to be appropriate for salmonid use (e.g., Figure 4 and Figure 13). However, some materials of artificial origin (e.g.,
broken concrete, angular rock) were also observed in the channel, and bank armoring (e.g., angular rock, milled
lumber) is present, particularly upstream of the crossing.
Pools are present throughout the observed reach, typically associated with LWM and/or naturally occurring boulder
clusters forcing small steps followed by small pools (e.g., Figures 3, 4, 5, 6 and 9). LWM is generally limited, except
in a few select locations described above (Figures 8 and 9). Several key pieces of LWM are present in the short
reach immediately upstream and immediately downstream of the crossing, but overall the quantities currently
occurring are insufficient to provide optimal fish habitat conditions.
12BRiparian Areas
Panther Creek flows through a forested ravine, with urban residential, commercial, and institutional development
beyond the immediate riparian area at the top of the valley walls. The vegetated ravine is typically approximately
130 to 200 feet wide in the vicinity of the project crossing both upstream and downstream, interrupted only by
Talbot Road South, which crosses perpendicular to the stream.
The Panther Creek ravine immediately upstream of the crossing is forested, creating dense shade even on the hot
summer day that characterized site reconnaissance. Typical forest canopy species include bigleaf maple (Acer
macrophyllum), red alder (Alnus rubra), and Western redcedar (Thuja plicata). Understory vegetation is severely
File No. 0693-093-00
August 14, 2023
Page 7
compromised in this reach by invasive species, including English ivy (Hedera helix) and Himalayan blackberry
(Rubus armeniacus). Native understory vegetation includes salmonberry (Rubus spectabilis), vine maple (Acer
circinatum), sword fern (Polystichum munitium) and field horsetail (Equisetum arvense).
Downstream of the project crossing, the forest canopy is more open immediately adjacent to the stream. The open
area is dominated by invasive species, typically Himalayan blackberry and reed canarygrass (Phalaris arundinacea),
as well as native salmonberry and beaked hazelnut (Corylus cornuta). Forested canopy set back from the stream
bank includes bigleaf maple (Acer macrophyllum), Western redcedar (Thuja plicata) and some Western hemlock
(Tsuga heterophylla). Forested areas and slopes in this area are also affected by proliferate English ivy (Hedera
helix).
6BREFERENCES
Mullineaux, D.R. 1965. Geologic map of the Renton quadrangle, King County, Washington, Washington: U.S.
Geological Survey Numbered Series Map 405, scale 1:24,000,
https://ngmdb.usgs.gov/Prodesc/proddesc_872.htm.
Washington Department of Fish and Wildlife. 2022. Fish Passage & Diversion Screening Inventory Database Site
Description Report: Site ID 931933. February 28, 2022.
Washington Department of Fish and Wildlife. 2023. Washington State Fish Passage Online Database. Accessed
July 2023. Available at: https://geodataservices.wdfw.wa.gov/hp/fishpassage/
index.html.
Washington State Department of Natural Resources. (2021). King County (WA) West 2021. Retrieved from WA
LiDAR Portal : https://lidarportal.dnr.wa.gov/
File No. 0693-093-00
August 14, 2023
Page 8
7BPHOTOS
Figure 1. Project crossing inlet, looking downstream.
File No. 0693-093-00
August 14, 2023
Page 9
Figure 2. Project crossing outlet, looking upstream
File No. 0693-093-00
August 14, 2023
Page 10
Figure 4. At bottom of reference reach, looking downstream
Figure 3. Upstream end of reference reach, looking upstream
File No. 0693-093-00
August 14, 2023
Page 11
Figure 5. Cobble and boulder steps within the reference reach, looking upstream
Figure 6. Example of confined left bank and accessible right bank floodplain within reference reach, looking upstream
File No. 0693-093-00
August 14, 2023
Page 12
Figure 8. Large wood jam and scour pool approximately 35 feet upstream of crossing inlet, looking downstream
Figure 7. Channel spanning log creating a 1.5-foot drop into inlet
File No. 0693-093-00
August 14, 2023
Page 13
Figure 10: Small branches racked up on and beside an approximately 36-inch diameter boulder within the reference reach, looking upstream
Figure 9. LWM within channel approximately 85 feet downstream of the outlet, looking upstream
File No. 0693-093-00
August 14, 2023
Page 14
Figure 11. Reach-based longitudinal profile of the project crossing
File No. 0693-093-00
August 14, 2023
Page 15
Figure 13. Pool-riffle channel morphology downstream of the outlet, looking upstream
Figure 12. Channel spanning cobble and gravel bar at downstream end of outlet scour pool, looking downstream
File No. 0693-093-00
August 14, 2023
Page 16
Figure 14. Siltstone and mudstone exposed along the left bank near the outlet
File No. 0693-093-00
August 14, 2023
Page 17
Figure 15. Typical open riparian canopy downstream, dominated by invasive species with few trees
set further back from the stream channel.
Appendix B
FEMA Flood Panel
National Flood Hazard Layer FIRMette
0 500 1,000 1,500 2,000250
Feet
Ü
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
SPECIAL FLOOD
HAZARD AREAS
Without Base Flood Elevation (BFE)
Zone A, V, A99
With BFE or DepthZone AE, AO, AH, VE, AR
Regulatory Floodway
0.2% Annual Chance Flood Hazard, Areas
of 1% annual chance flood with average
depth less than one foot or with drainage
areas of less than one square mileZone X
Future Conditions 1% Annual
Chance Flood HazardZone X
Area with Reduced Flood Risk due to
Levee. See Notes.Zone X
Area with Flood Risk due to LeveeZone D
NO SCREEN Area of Minimal Flood Hazard Zone X
Area of Undetermined Flood HazardZone D
Channel, Culvert, or Storm Sewer
Levee, Dike, or Floodwall
Cross Sections with 1% Annual Chance
17.5 Water Surface Elevation
Coastal Transect
Coastal Transect Baseline
Profile Baseline
Hydrographic Feature
Base Flood Elevation Line (BFE)
Effective LOMRs
Limit of Study
Jurisdiction Boundary
Digital Data Available
No Digital Data Available
Unmapped
This map complies with FEMA's standards for the use of
digital flood maps if it is not void as described below.
The basemap shown complies with FEMA's basemap
accuracy standards
The flood hazard information is derived directly from the
authoritative NFHL web services provided by FEMA. This map
was exported on 11/7/2023 at 1:38 AM and does not
reflect changes or amendments subsequent to this date and
time. The NFHL and effective information may change or
become superseded by new data over time.
This map image is void if the one or more of the following map
elements do not appear: basemap imagery, flood zone labels,
legend, scale bar, map creation date, community identifiers,
FIRM panel number, and FIRM effective date. Map images for
unmapped and unmodernized areas cannot be used for
regulatory purposes.
Legend
OTHER AREAS OF
FLOOD HAZARD
OTHER AREAS
GENERAL
STRUCTURES
OTHER
FEATURES
MAP PANELS
8
B 20.2
The pin displayed on the map is an approximate
point selected by the user and does not represent
an authoritative property location.
1:6,000
122°13'W 47°26'54"N
122°12'22"W 47°26'30"N
Basemap Imagery Source: USGS National Map 2023
Appendix C
Hydraulic Modeling Summary Results
Source(s): HEC-RAS version 6.4.1
Figure C-1
Panther Creek Culvert Replacement
Existing Conditions 2-Year Flow Velocity
00693-093-00 Date Exported: 01/31/2025
1
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.
Panther Creek at Talbot Road S.
Culvert Replacement Project
Renton, Washington
Outlet boundary condition
Inlet boundary condition
Source(s): HEC-RAS version 6.4.1
Figure C-2
Panther Creek Culvert Replacement
10 Percent Design Conditions 2-Year Flow Velocity
00693-093-00 Date Exported: 01/31/2025
1
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.
Outlet boundary condition
Inlet boundary condition
Bridge design linework
Panther Creek at Talbot Road S.
Culvert Replacement Project
Renton, Washington
Source(s): HEC-RAS version 6.4.1
Figure C-3
Panther Creek Culvert Replacement
Existing Conditions Water Surface Profiles
00693-093-00 Date Exported: 01/31/2025
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.
Talbot Rd S
Panther Creek at Talbot Road S.
Culvert Replacement Project
Renton, Washington
Source(s): HEC-RAS version 6.4.1
Figure C-4
Panther Creek Culvert Replacement
10 Percent Design Water Surface Profiles
00693-093-00 Date Exported: 01/31/2025
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.
Talbot Rd S
Proposed Bridge Extents
Panther Creek at Talbot Road S.
Culvert Replacement Project
Renton, Washington
Appendix D
10 Percent Design Stream Plans
W
UP
P
T
P
P
P
T
LT
LT
X
X
X
X
X
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
P
P
P
P
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
X
X
X
X
X
X
X
X
XX
X
X
X
X
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
OH
WOHW
OHW
OHW
O
H
W
O
H
W
OH
W
OHW
O
H
W
O
H
W
O
H
W
O
H
W
OHW
O
H
W
OHW
X X
P
P
P
TC
TC
TC
P
P
OH
OH
TC
TC
TC
OH
OHOH
P
O
H
W
O
H
W
OHW
OH
W
O
H
W
OHWOHW
O
H
W
O
H
W
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H
W
O
H
W
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H
W
O
H
W
O
H
W
O
H
W
O
H
W
OHW
OH
W
OHW
OH
W
OH
W
OHW
OHW
OHW
OH OH
SD
SD
SD
SD
SD
SD
SD
SD
SD
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SSMH #1
RIM = 99.38
IE 18" CONC (N) = 87.45
IE 18" CONC (S) = 89.16
IE 8" CONC (E) = 88.64
IE 8" CONC (W) = 88.60
8" TO 6" ADAPTER WEST OF SSMH
SS
SS
SS
SS
SS
P
TPN 3123059065
3901 TALBOT RD S.
PUBLIC HOSPITAL DISTRICT #1
TPN 3023059034
3401 TALBOT RD S.
PUBLIC HOSPITAL DISTRICT #1
TPN 3023059111
350 S 38TH CT.
BROLIN - VALLEY VIEW LLC
TPN 3023059054
N2B2 PROPERTIES LLC
3721 TALBOT RD S.
TPN 8558600185
VERLA M BATES
501 S 38TH CT.
TPN 8558600190
JAMES V BALISE
507 S 38TH CT.
TPN 8558600195
REBECCA HILL
515 S 38TH CT.
TPN 8558600200
DANIEL HELDELE & KIMBE OLALIA
521 S 38TH CT.
TPN 3123059026
TALBOT SPRING LLC
17600 TALBOT RD S.
80
85
90
95
7575
80
80
85
8
5
90
95
75
75
80
80
85
90
95
6
5
7
0
75
75
80
80
85
85
90
90
95
95
65
70
75
80
85
90
95 75
80
85
90
95
75
80
80
6
0
6
5
70
7
5
8
0
85
90
95
WETL
WETL
WETL
W
E
T
L
WETL
WETL
S
P
A
N
T
H
E
R
C
R
E
E
K
IE 36" CMP = 64.30
℄
12" STEEL WATERLINE(R)
20" WATERLINE(R)
(ABANDONED)
IE 36" CMP = 69.66CONCRETE
WING WALL
EXISTING THALWEG
IE 24" CMP = 81.90
IE 12" CMP = 78.00
P
A
N
T
H
E
R
C
R
E
E
K
B-1
B-2
TA
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B
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T
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0+
0
0
0
+
5
0
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+
0
0
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+
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9
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OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
SS
SS
SS
SSMH #2
RIM = 93.62
IE 12" CONC (N) = 80.71
IE 12" CONC (E) = 80.65
IE 18" CONC (S) = 79.90
IE 18" CONC (W) = 79.87
TA
L
B
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T
R
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A
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KTF/ECD
SCY
JC
----
05/27/25
ST-1EXISTING STREAM CONDITIONS 61
32135
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NO.DATE BY ISSUE / DESCRIPTION PREPARED FOR:DRAWING NUMBER:
SHEET: OF
DESIGNED BY:
DRAWN BY:
APPROVED BY:
DATE:
REVISION NO.:
DR
A
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PRE
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PANTHER CREEK AT TALBOT ROAD S.
CULVERT REPLACEMENT PROJECT
RENTON, WASHINGTON
SCALE IN FEET
0 20 40
N
SOURCE(S):
·SURVEY FROM KPFF, DATED 7/14/2023.
COORDINATE SYSTEM: WASHINGTON STATE PLANE,
NORTH ZONE, NAD83, US FOOT.
WETL
OHW
LEGEND (EXISTING)
U
P
T
S
G
TC
OH
P
W
B-1PARCEL PROPERTY LINE
CULVERT
ORDINARY HIGH WATER LINE
WETLAND LINE
PANTHER CREEK THALWEG ALIGNMENT
EXISTING MAJOR (5-FT) CONTOUR LINE
EXISTING MINOR (1-FT) CONTOUR LINE
UNDERGROUND POWER
OVERHEAD UTILITIES
UNDERGROUND TELECOMMUNICATIONS
WATER LINE
GAS LINE
SANITARY SEWER MAINTENANCE HOLE
POWER POLE
TELECOMMUNICATIONS POLE
UTILITY POLE
TREE CONIFER
TREE DECIDUOUS
BORING BY GEOENGINEERS, INC., 2023
SUPPLEMENTAL PLAN AREA
(APPROXIMATE 567 FT. NORTH OF SSMH #1)
W
UP
P
T
P
P
P
T
LT
LT
X
X
X
X
X
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
P
P
P
P
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
X
X
X
X
X
X
X
X
XX
X
X
X
X
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
OH
WOHW
OHW
OHW
O
H
W
O
H
W
OH
W
OHW
O
H
W
O
H
W
O
H
W
O
H
W
OHW
O
H
W
OHW
X X
P
P
P
TC
TC
TC
P
P
OH
OH
TC
TC
TC
OH
OHOH
P
O
H
W
O
H
W
OHW
OH
W
O
H
W
OHWOHW
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
OHW
OH
W
OHW
OH
W
OH
W
OHW
OHW
OHW
OH OH
SD
SD
SD
SD
SD
SD
SD
SD
SD
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SSMH #1
RIM = 99.38
IE 18" CONC (N) = 87.45
IE 18" CONC (S) = 89.16
IE 8" CONC (E) = 88.64
IE 8" CONC (W) = 88.60
8" TO 6" ADAPTER WEST OF SSMH
SS
SS
SS
SS
SS
P
TPN 3123059065
3901 TALBOT RD S.
PUBLIC HOSPITAL DISTRICT #1
TPN 3023059034
3401 TALBOT RD S.
PUBLIC HOSPITAL DISTRICT #1
TPN 3023059111
350 S 38TH CT.
BROLIN - VALLEY VIEW LLC
TPN 3023059054
N2B2 PROPERTIES LLC
3721 TALBOT RD S.
TPN 8558600185
VERLA M BATES
501 S 38TH CT.
TPN 8558600190
JAMES V BALISE
507 S 38TH CT.
TPN 8558600195
REBECCA HILL
515 S 38TH CT.
TPN 8558600200
DANIEL HELDELE & KIMBE OLALIA
521 S 38TH CT.
TPN 3123059026
TALBOT SPRING LLC
17600 TALBOT RD S.
80
85
90
95
7575
80
80
85
8
5
90
95
75
75
80
80
85
90
95
6
5
7
0
75
75
80
80
85
85
90
90
95
95
65
70
75
80
85
90
95 75
80
85
90
95
75
80
80
6
0
6
5
70
7
5
8
0
85
90
95
WETL
WETL
WETL
W
E
T
L
WETL
WETL
S
21
+
0
0
22
+
0
0
23
+
0
0
0+61
1
+
0
0
1
+
5
0
2+00
2+50
3+00
3+50
4+00
4
+
5
0
4
+
8
8
65
70
75
80
85
90
65
70
75
80
85
90
95
75
75
8
0
6
0
6
0
P
A
N
T
H
E
R
C
R
E
E
K
℄
P
A
N
T
H
E
R
C
R
E
E
K
B-1
B-2
TA
L
B
O
T
R
O
A
D
S
O
U
T
H
0+
0
0
0
+
5
0
1
+
0
0
1
+
5
0
2+00
2+50
3+00
3+50
4+00
4
+
5
0
5
+
0
0
5+
5
0
5
+
9
5
0+61
1
+
0
0
1
+
5
0
2+00
2+50
3+00
3+50
4+00
4
+
5
0
4
+
8
8
0
+
6
1
0+
0
0
0
+
5
0
4
+
8
5
5
+
0
0
5
+
5
0
5
+
6
8
EXISTING THALWEG
EXISTING
THALWEG
PROPOSED THALWEG (SEE SHEET
ST-3 FOR PROFILE AND SECTION)
PROPOSED
BRIDGE
PROPOSED THALWEG
ALIGNMENT (STA. 4+85.5)
PROPOSED THALWEG
ALIGNMENT (STA. 0+61.31)
CONTRACTOR DESIGNED
ACCESS ROUTE
CONSTRUCT CHANNEL
DOWNSTREAM OF
EXISTING CULVERT, AND
WETLAND RESTORATION,
IN SINGLE CONTINUOUS
EFFORT TO MINIMIZE
DURATION OF WETLAND
IMPACTS. IMPLEMENT
TEMPORARY STREAM
BYPASS (SEE SHEET ST-4).
FILL SCOUR HOLE UP TO
STREAMBED CHANNEL
SUBGRADE WITH NATIVE
SEDIMENT EXCAVATED
FROM ELSEWHERE ON SITE.
EXISTING
THALWEG
SEE BRIDGE PLANS
FOR GRADING SLOPES
ABOVE STREAM ZONE
KTF/ECD
SCY
JC
----
05/27/25
ST-2STREAM PLAN 62
32135
Pl
o
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2
5
,
1
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\
0
\
0
6
9
3
0
9
3
\
C
A
D
\
0
0
\
P
a
n
t
h
e
r
C
r
e
e
k
C
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l
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e
r
t
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e
p
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u
l
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t
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e
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a
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n
\
v
0
1
_
1
0
_
P
e
r
c
e
n
t
\
0
6
9
3
0
9
3
0
0
_
S
h
t
2
_
S
T
-
2
[
S
t
r
e
a
m
P
l
a
n
]
.
d
w
g
NO.DATE BY ISSUE / DESCRIPTION PREPARED FOR:DRAWING NUMBER:
SHEET: OF
DESIGNED BY:
DRAWN BY:
APPROVED BY:
DATE:
REVISION NO.:
DR
A
F
T
S
U
B
M
I
T
T
A
L
-
N
O
T
F
O
R
C
O
N
S
T
R
U
C
T
I
O
N
PRE
L
I
M
I
N
A
R
Y
PANTHER CREEK AT TALBOT ROAD S.
CULVERT REPLACEMENT PROJECT
RENTON, WASHINGTON
SCALE IN FEET
0 20 40
N
SOURCE(S):
·SURVEY FROM KPFF, DATED 7/14/2023.
COORDINATE SYSTEM: WASHINGTON STATE PLANE,
NORTH ZONE, NAD83, US FOOT.
WETL
OHW
LEGEND (EXISTING)
U
P
T
S
G
TC
OH
P
W
LEGEND (PROPOSED)
B-1PARCEL PROPERTY LINE
CULVERT
ORDINARY HIGH WATER LINE
WETLAND LINE
PANTHER CREEK THALWEG ALIGNMENT
EXISTING MAJOR (5-FT) CONTOUR LINE
EXISTING MINOR (1-FT) CONTOUR LINE
UNDERGROUND POWER
OVERHEAD UTILITIES
UNDERGROUND TELECOMMUNICATIONS
WATER LINE
GAS LINE
SANITARY SEWER MAINTENANCE HOLE
POWER POLE
TELECOMMUNICATIONS POLE
UTILITY POLE
TREE CONIFER
TREE DECIDUOUS
PANTHER CREEK THALWEG ALIGNMENT
BORING BY GEOENGINEERS, INC., 2023
PROPOSED MAJOR (5-FT) CONTOUR LINE
PROPOSED MINOR (1-FT) CONTOUR LINE
EL
E
V
A
T
I
O
N
(
F
E
E
T
)
EL
E
V
A
T
I
O
N
(
F
E
E
T
)
STATION (FEET)
40
50
60
70
80
90
100
110
40
50
60
70
80
90
100
110
0+00 0+20 0+40 0+60 0+80 1+00 1+20 1+40 1+60 1+80 2+00 2+20 2+40 2+60 2+80 3+00 3+20 3+40 3+60 3+80 4+00 4+20 4+40 4+60 4+80 5+00 5+20 5+40 5+60 5+80
MATCH TO EXISTING GRADE
STA. 0+61.3'
ELEV. 56.3'
MATCH TO EXISTING GRADE
STA. 4+87.9'
ELEV. 75.7'
EXISTING GROUND SURFACE
PROPOSED THALWEG (SEE NOTE 1)
REMOVE EXISTING 36" CMP CULVERTEXISTING PANTHER CREEK THALWEG
428.4'
TALBOT ROAD S. CL
STREAMBED MATERIAL (NATIVE
MATERIAL MAY BE ACCEPTABLE,
TBD DURING CONSTRUCTION.
STREAM ZONE
18.0'
9.4'
EL
E
V
A
T
I
O
N
(
F
E
E
T
)
EL
E
V
A
T
I
O
N
(
F
E
E
T
)
OFFSET (FEET)
55
60
65
70
75
80
85
55
60
65
70
75
80
85
0 5 10 15 200-5-10-15-20
1
1
1
1
VARIES 2:
1 2:110:1 10:1 VARIES
2:1
2:
1
EXISTING
GROUND
SURFACE
PROPOSED GRADE, SEE BRIDGE
PLANS FOR GRADING SLOPES
ABOVE STREAM ZONE
MATCH TO EXISTING GRADE
MATCH TO EXISTING GRADE
TOPSOIL AND NATIVE PLANTING
ON FLOODPLAIN BENCHES
0.5'
0.95'
FILL: TYPICALLY
CLAYEY TO SILTY FINE
SAND WITH GRAVEL
(VARIABLE, LOOSE)
POSSIBLE ZONE OF RENTON FORMATION
BEDROCK (INFERRED FROM
GEOTECHNICAL BORINGS). SEE NOTE 3.
POSSIBLE ZONE OF VERY DENSE
GLACIAL TILL (INFERRED FROM
GEOTECHNICAL BORINGS). SEE NOTE 3.
THALWEG:
IE: 66.72 FT
PRELIMINARY ESTIMATE
OF SCOUR DEPTH (3 FT)
STREAMBED CHANNEL SUBGRADE
KTF/ECD
SCY
JC
----
05/27/25
ST-3STREAM PROFILE AND SECTION 63
32135
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\
0
\
0
6
9
3
0
9
3
\
C
A
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\
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0
\
P
a
n
t
h
e
r
C
r
e
e
k
C
u
l
v
e
r
t
R
e
p
l
a
c
e
m
e
n
t
\
C
u
l
v
e
r
t
R
e
p
l
a
c
e
m
e
n
t
D
e
s
i
g
n
\
v
0
1
_
1
0
_
P
e
r
c
e
n
t
\
0
6
9
3
0
9
3
0
0
_
S
h
t
3
_
S
T
-
3
[
S
t
r
e
a
m
P
r
o
f
i
l
e
a
n
d
S
e
c
t
i
o
n
]
.
d
w
g
NO.DATE BY ISSUE / DESCRIPTION PREPARED FOR:DRAWING NUMBER:
SHEET: OF
DESIGNED BY:
DRAWN BY:
APPROVED BY:
DATE:
REVISION NO.:
DR
A
F
T
S
U
B
M
I
T
T
A
L
-
N
O
T
F
O
R
C
O
N
S
T
R
U
C
T
I
O
N
PRE
L
I
M
I
N
A
R
Y
PANTHER CREEK AT TALBOT ROAD S.
CULVERT REPLACEMENT PROJECT
RENTON, WASHINGTON
SCALE IN FEET
0 20 40
TYPICAL CREEK SECTION
VERTICAL EXAGGERATION: 2X
DATUM: NAVD88.
NOTES:
1.CREEK THALWEG WILL HAVE VERTICAL UNDULATIONS TO
CREATE POOL/RIFFLE HABITAT ZONES.
2.RENTON FORMATION BEDROCK MAY BE PRESENT. TBD DURING
CONSTRUCTION. PROPOSED STREAMBED SUBSTRATE WILL BE
MIX OF FINES, SAND, GRAVEL, AND COBBLES SIMILAR TO
EXISTING REFERENCE REACH NATIVE MATERIAL EXPOSED BY
EXCAVATION OF ROAD EMBANKMENT MAY BE RETAINED IN
PLACE IF SUITABLE.
3.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.
4.EXISTING UTILITIES NOT SHOWN.
PROFILE VIEW
SCALE IN FEET
0 5 10
W
UP
P
T
P
P
P
T
LT
LT
X
X
X
X
X
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
P
P
P
P
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
X
X
X
X
X
X
X
X
XX
X
X
X
X
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
OH
WOHW
OHW
OHW
O
H
W
O
H
W
OH
W
OHW
O
H
W
O
H
W
O
H
W
O
H
W
OHW
O
H
W
OHW
X X
P
P
P
TC
TC
TC
P
P
OH
OH
TC
TC
TC
OH
OHOH
P
O
H
W
O
H
W
OHW
OH
W
O
H
W
OHWOHW
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
OHW
OH
W
OHW
OH
W
OH
W
OHW
OHW
OHW
OH OH
SD
SD
SD
SD
SD
SD
SD
SD
SD
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SSMH #1
RIM = 99.38
IE 18" CONC (N) = 87.45
IE 18" CONC (S) = 89.16
IE 8" CONC (E) = 88.64
IE 8" CONC (W) = 88.60
8" TO 6" ADAPTER WEST OF SSMH
SS
SS
SS
SS
SS
P
TPN 3123059065
3901 TALBOT RD S.
PUBLIC HOSPITAL DISTRICT #1
TPN 3023059034
3401 TALBOT RD S.
PUBLIC HOSPITAL DISTRICT #1
TPN 3023059111
350 S 38TH CT.
BROLIN - VALLEY VIEW LLC
TPN 3023059054
N2B2 PROPERTIES LLC
3721 TALBOT RD S.
TPN 8558600185
VERLA M BATES
501 S 38TH CT.
TPN 8558600190
JAMES V BALISE
507 S 38TH CT.
TPN 8558600195
REBECCA HILL
515 S 38TH CT.
TPN 8558600200
DANIEL HELDELE & KIMBE OLALIA
521 S 38TH CT.
TPN 3123059026
TALBOT SPRING LLC
17600 TALBOT RD S.
80
85
90
95
7575
80
80
85
8
5
90
95
75
75
80
80
85
90
95
6
5
7
0
75
75
80
80
85
85
90
90
95
95
65
70
75
80
85
90
95 75
80
85
90
95
75
80
80
6
0
6
5
70
7
5
8
0
85
90
95
WETL
WETL
WETL
W
E
T
L
WETL
WETL
S
21
+
0
0
22
+
0
0
23
+
0
0
0+61
1
+
0
0
1
+
5
0
2+00
2+50
3+00
3+50
4+00
4
+
5
0
4
+
8
8
65
70
75
80
85
90
65
70
75
80
85
90
95
75
75
8
0
6
0
6
0
P
A
N
T
H
E
R
C
R
E
E
K
℄
P
A
N
T
H
E
R
C
R
E
E
K
B-1
B-2
TA
L
B
O
T
R
O
A
D
S
O
U
T
H
0+61
1
+
0
0
1
+
5
0
2+00
2+50
3+00
3+50
4+00
4
+
5
0
4
+
8
8
0
+
6
1
0+
0
0
0
+
5
0
4
+
8
5
5
+
0
0
5
+
5
0
5
+
6
8
EXISTING THALWEG
EXISTING
THALWEG
PROPOSED THALWEG (SEE SHEET
ST-3 FOR PROFILE AND SECTION)
PROPOSED
BRIDGE
PROPOSED THALWEG
ALIGNMENT (STA. 4+85.5)
PROPOSED THALWEG
ALIGNMENT (STA. 0+61.31)
CONTRACTOR DESIGNED
TEMPORARY STREAM
BYPASS. INSTALL BELOW
EXISTING STA 5+50.
BYPASS FLOW DIFFUSER OR OTHER
EROSION CONTROL MEASURES AS
DESIGNED BY CONTRACTOR. MAINTAIN
BYPASS DISCHARGE UPSTREAM OF
WETLAND AREA TO THE MAXIMUM
EXTENT POSSIBLE EXCEPT WITH
ACTIVELY CONSTRUCTING CHANNEL
DOWNSTREAM OF EXISTING CULVERT.
IF BYPASS HAS PIPE OVER ROADWAY, PROVIDE STEEL
PLATES WITH SLOPE LESS THAN 20:1, MINIMUM 12
FT WIDE FOR SINGLE LANE TRAFFIC AND 24 FT WIDE
FOR DOUBLE LANE TRAFFIC, SUITABLE FOR HEAVY
TRUCK TRAFFIC AND FIRE TRUCKS.
KTF/ECD
SCY
JC
----
05/27/25
ST-4TEMPORARY STREAM BYPASS PLAN 64
32135
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0
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6
9
3
0
9
3
\
C
A
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d
w
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NO.DATE BY ISSUE / DESCRIPTION PREPARED FOR:DRAWING NUMBER:
SHEET: OF
DESIGNED BY:
DRAWN BY:
APPROVED BY:
DATE:
REVISION NO.:
DR
A
F
T
S
U
B
M
I
T
T
A
L
-
N
O
T
F
O
R
C
O
N
S
T
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U
C
T
I
O
N
PRE
L
I
M
I
N
A
R
Y
PANTHER CREEK AT TALBOT ROAD S.
CULVERT REPLACEMENT PROJECT
RENTON, WASHINGTON
SCALE IN FEET
0 20 40
N
SOURCE(S):
·SURVEY FROM KPFF, DATED 7/14/2023.
COORDINATE SYSTEM: WASHINGTON STATE PLANE,
NORTH ZONE, NAD83, US FOOT.
WETL
OHW
LEGEND (EXISTING)
U
P
T
S
G
TC
OH
P
W
LEGEND (PROPOSED)
B-1PARCEL PROPERTY LINE
CULVERT
ORDINARY HIGH WATER LINE
WETLAND LINE
PANTHER CREEK THALWEG ALIGNMENT
EXISTING MAJOR (5-FT) CONTOUR LINE
EXISTING MINOR (1-FT) CONTOUR LINE
UNDERGROUND POWER
OVERHEAD UTILITIES
UNDERGROUND TELECOMMUNICATIONS
WATER LINE
GAS LINE
SANITARY SEWER MAINTENANCE HOLE
POWER POLE
TELECOMMUNICATIONS POLE
UTILITY POLE
TREE CONIFER
TREE DECIDUOUS
PANTHER CREEK THALWEG ALIGNMENT
BORING BY GEOENGINEERS, INC., 2023
PROPOSED MAJOR (5-FT) CONTOUR LINE
PROPOSED MINOR (1-FT) CONTOUR LINE
F
L
O
W
RACKING MATERIAL (15 PIECES TOTAL)
FLOW
PLAN
FLOW
PLAN
APPROXIMATELY
40° FROM
CHANNEL CL
APPROXIMATELY
60° BETWEEN
LOGS
SCALE:
2
ST-2
TYPICAL CHANNEL SPANNING LOG DETAIL
NOT TO SCALE
1. INSTALL TYPE C LOG WITH
THE ORIENTATION SHOWN. THE
BOTTOM ELEVATION OF EMBEDDED
END SHOULD BE 1-FT BELOW THE
THALWEG ELEVATION. COVER THE
EMBEDDED END WITH STREAMBED
MATERIAL.
2. PLACE TYPE A LOG SUCH THAT IT
CROSSES THE TYPE C LOG BELOW, MAKING
GOOD CONTACT WITH IT, AT OR IMMEDIATELY
BEHIND THE TOP OF BANK. THE STEM END
SHOULD BE EMBEDDED IN THE OPPOSITE BANK
SUCH THAT IT IS COMPLETELY BURIED STARTING
AT THE TOP OF BANK ELEVATION AND THE
BOTTOM OF THE STEM END OF THE LOG IS
1-FOOT BELOW THE THALWEG ELEVATION.
4. PLACE A 1.5-FT DIAMETER
BOULDER BEHIND AND IN CONTACT
WITH BOTH LOGS AS SHOWN.
5. PLACE A 2-FT DIAMETER
BOULDER IN CONTACT WITH
BOTH LOGS AS SHOWN.
CHANNEL TOP-OF-BANK
CHANNEL TOE-OF-BANK
CHANNEL TOP-OF-BANK
CHANNEL TOE-OF-BANK
3.COVER BOLE END OF
TYPE A LOG WITH STREAMBED
MATERIAL TO FINISHED GRADE
AND PLACE A 2-FT DIAMETER
BOULDER ATOP THIS END.
LOG WITH ROOT WAD:
16-20 INCH DBH, 30 FT
LONG.
LOG: 8-12 INCH
DIA. 30 FT LONG.
SCALE:
1
ST-2
TYPICAL SWEEPER DETAIL PLAN
NOT TO SCALE
A-A'
-
TOP-OF-BANK
TOE-OF-BANK
BOULDER ANCHORS
SCOUR HOLE
EXTEND TREE TIPS TO 2/3 POOL WIDTH
RACKING MATERIAL (6 PIECES TOTAL)
BURIED
PORTION
OF TREES
BURIED PORTION OF TREE SHOULD
BE NEARLY PARALLEL TO
UPSTREAM PORTION OF CREEK
FLO
W
W/2
W/2
FL
O
W
LOG WITH ROOT WAD: 6-8 INCH DIAMETER
AT BREAST HEIGHT (DBH), 20 FT LONG,
RETAIN BRANCHES ON TOP HALF, TIE UP
BRANCHES WITH HEAVY JUTE TWINE,
EXTEND TOP 1/3 INTO CHANNEL.
SCALE:
3
ST-2
TYPICAL BANK ROOT WAD DETAIL PLAN
NOT TO SCALE
B-B'
-
TOP-OF-BANK
TOE-OF-BANK
LOG WITH ROOT WADS, 8-10"
DBH, 15 FT LONG (TYP.)
ANCHORS
SCALE:
A-A'
ST-2
TYPICAL SWEEPER SECTION
NOT TO SCALE
STREAMBED MATERIAL (NATIVE
MATERIAL MAY BE ACCEPTABLE,
TBD DURING CONSTRUCTION.
LOG WITH ROOT WAD: 6-8 INCH DIAMETER
AT BREAST HEIGHT (DBH), 20 FT LONG,
RETAIN BRANCHES ON TOP HALF, TIE UP
BRANCHES WITH HEAVY JUTE TWINE,
EXTEND TOP 1/3 INTO CHANNEL.
SCALE:
B-B'
ST-2
TYPICAL BANK ROOT WAD SECTION
NOT TO SCALE
DBH
LOG WITH ROOT WADS, 8-10"
DBH, 15 FT LONG (TYP.)
KTF/ECD
SCY
JC
----
05/27/25
ST-5LARGE WOOD DETAILS 65
32135
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NO.DATE BY ISSUE / DESCRIPTION PREPARED FOR:DRAWING NUMBER:
SHEET: OF
DESIGNED BY:
DRAWN BY:
APPROVED BY:
DATE:
REVISION NO.:
DR
A
F
T
S
U
B
M
I
T
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A
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-
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O
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F
O
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O
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I
O
N
PRE
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I
N
A
R
Y
PANTHER CREEK AT TALBOT ROAD S.
CULVERT REPLACEMENT PROJECT
RENTON, WASHINGTON
W
UP
P
T
P
P
P
T
LT
LT
X
X
X
X
X
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
W
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
TC
P
P
P
P
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
OH
X
X
X
X
X
X
X
X
XX
X
X
X
X
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
OH
WOHW
OHW
OHW
O
H
W
O
H
W
OH
W
OHW
O
H
W
O
H
W
O
H
W
O
H
W
OHW
O
H
W
OHW
X X
P
P
P
TC
TC
TC
P
P
OH
OH
TC
TC
TC
OH
OHOH
P
O
H
W
O
H
W
OHW
OH
W
O
H
W
OHWOHW
O
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W
O
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W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
O
H
W
OHW
OH
W
OHW
OH
W
OH
W
OHW
OHW
OHW
OH OH
SD
SD
SD
SD
SD
SD
SD
SD
SD
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SS
SSMH #1
RIM = 99.38
IE 18" CONC (N) = 87.45
IE 18" CONC (S) = 89.16
IE 8" CONC (E) = 88.64
IE 8" CONC (W) = 88.60
8" TO 6" ADAPTER WEST OF SSMH
SS
SS
SS
SS
SS
P
TPN 3123059065
3901 TALBOT RD S.
PUBLIC HOSPITAL DISTRICT #1
TPN 3023059034
3401 TALBOT RD S.
PUBLIC HOSPITAL DISTRICT #1
TPN 3023059111
350 S 38TH CT.
BROLIN - VALLEY VIEW LLC
TPN 3023059054
N2B2 PROPERTIES LLC
3721 TALBOT RD S.
TPN 8558600185
VERLA M BATES
501 S 38TH CT.
TPN 8558600190
JAMES V BALISE
507 S 38TH CT.
TPN 8558600195
REBECCA HILL
515 S 38TH CT.
TPN 8558600200
DANIEL HELDELE & KIMBE OLALIA
521 S 38TH CT.
TPN 3123059026
TALBOT SPRING LLC
17600 TALBOT RD S.
80
85
90
95
7575
80
80
85
8
5
90
95
75
75
80
80
85
90
95
6
5
7
0
75
75
80
80
85
85
90
90
95
95
65
70
75
80
85
90
95 75
80
85
90
95
75
80
80
6
0
6
5
70
7
5
8
0
85
90
95
WETL
WETL
WETL
W
E
T
L
WETL
WETL
S
21
+
0
0
22
+
0
0
23
+
0
0
0+61
1
+
0
0
1
+
5
0
2+00
2+50
3+00
3+50
4+00
4
+
5
0
4
+
8
8
65
70
75
80
85
90
65
70
75
80
85
90
95
75
75
8
0
6
0
6
0
0
+
6
1
0+
0
0
0
+
5
0
4
+
8
5
5
+
0
0
5
+
5
0
5
+
6
8
0+61
1
+
0
0
1
+
5
0
2+00
2+50
3+00
3+50
4+00
4
+
5
0
4
+
8
8
P
A
N
T
H
E
R
C
R
E
E
K
℄
P
A
N
T
H
E
R
C
R
E
E
K
TA
L
B
O
T
R
O
A
D
S
O
U
T
H
EXISTING THALWEG
EXISTING
THALWEG
PROPOSED THALWEG (SEE SHEET
ST-3 FOR PROFILE AND SECTION)
PROPOSED
BRIDGE
PROPOSED THALWEG
ALIGNMENT (STA. 4+85.5)
PROPOSED THALWEG
ALIGNMENT (STA. 0+61.31)
BANKFULL CHANNEL
BASE OF 2:1 SLOPE
KTF/ECD
SCY
JC
----
05/27/25
LS-1LANDSCAPE RESTORATION PLAN 66
32135
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.
d
w
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NO.DATE BY ISSUE / DESCRIPTION PREPARED FOR:DRAWING NUMBER:
SHEET: OF
DESIGNED BY:
DRAWN BY:
APPROVED BY:
DATE:
REVISION NO.:
DR
A
F
T
S
U
B
M
I
T
T
A
L
-
N
O
T
F
O
R
C
O
N
S
T
R
U
C
T
I
O
N
PRE
L
I
M
I
N
A
R
Y
PANTHER CREEK AT TALBOT ROAD S.
CULVERT REPLACEMENT PROJECT
RENTON, WASHINGTON
SCALE IN FEET
0 20 40
N
SOURCE(S):
·SURVEY FROM KPFF, DATED 7/14/2023.
COORDINATE SYSTEM: WASHINGTON STATE PLANE,
NORTH ZONE, NAD83, US FOOT.
WETL
OHW
LEGEND (EXISTING)
U
P
T
S
G
TC
OH
P
W
PROPOSED PLANT COMMUNITIES
PARCEL PROPERTY LINE
CULVERT
ORDINARY HIGH WATER LINE
WETLAND LINE
PANTHER CREEK THALWEG ALIGNMENT
EXISTING MAJOR (5-FT) CONTOUR LINE
EXISTING MINOR (1-FT) CONTOUR LINE
UNDERGROUND POWER
OVERHEAD UTILITIES
UNDERGROUND TELECOMMUNICATIONS
WATER LINE
GAS LINE
SANITARY SEWER MAINTENANCE HOLE
POWER POLE
TELECOMMUNICATIONS POLE
UTILITY POLE
TREE CONIFER
TREE DECIDUOUS
RIPARIAN FRINGE (3,625 SQ. FT.)
WETLAND (1,443 SQ. FT.)
NATIVE FOREST (13,692 SQ. FT.)
LEGEND (PROPOSED)
PANTHER CREEK THALWEG ALIGNMENT
PROPOSED MAJOR (5-FT) CONTOUR LINE
PROPOSED MINOR (1-FT) CONTOUR LINE
Riparian Fringe
Common Name Scientific Name Quantity
Pacific Willow (stakes)Salix lucida 452
Sitka Willow (stakes)Salix sitchensis 452
Salmonberry Rubus spectabilis 99
Pacific Nine Bark Physocarpus captatus 66
Thimbleberry Rubus parviflorus 61
NatiYe Forest
Common Name Scientific Name Quantity
Big Leaf Maple Acer macrophyllum 16
Douglas Fir Pseudotsuga menziesii 16
Western Red Cedar Thuja plicata 16
Cascara Frangula purshiana 14
Vine Maple Acer circinatum 63
Osoberry Oemleria cerasiformis 63
Low Oregon Grape Mahonia nervosa 63
Salal Gaultheria shallon 65
Snowberry Symphoricarpos albus 65
Sword Fern Pulysteichum munitum 2855
Bracken Fern Pteridium aquilinum 2848
Wetland
Common Name Scientific Name Quantity
Pacific Nine Bark Physocarpus captatus 12
Hardhack Spiraea douglasii 11
Rice Cutgrass Leersia oryzoides 473
Red Fescue Festuca rubra 473
Small-fruited Bulrush Scirpus microcarpus 474
Appendix E
10 Percent Design Opinion of Probable Construction Cost
Estimate of Probable Cost
Panther Creek at Talbot Rd S Culvert Replacement Project
Renton, WA
Unit Price Unit QTY Total Cost QTY Total Cost QTY Total Cost QTY Total Cost QTY Total Cost QTY Total Cost QTY Total Cost QTY Total Cost
PREPARATION, GENERAL
1 Mobilization (10% of total)LS 1 439,050$ 1 468,254$ 1 560,166$ 1 505,166$ 1 443,468$ 1 479,831$ 1 566,063$ 1 511,063$
2 Clearing, Grubbing, and Roadside Cleanup 50,000$ AC 0.45 22,500$ 0.38 19,000$ 0.38 19,000$ 0.38 19,000$ 0.45 22,500$ 0.38 19,000$ 0.38 19,000$ 0.38 19,000$
3 Removal of Structures and Obstructions 10,000$ LS 1 10,000$ 1 10,000$ 1 10,000$ 1 10,000$ 1 10,000$ 1 10,000$ 1 10,000$ 1 10,000$
4 Sawcut Asphalt Conc. Pavement 45$ LF 101 4,545$ 101 4,545$ 101 4,545$ 101 4,545$ 101 4,545$ 101 4,545$ 101 4,545$ 101 4,545$
5 Planing Butiminous Pavement 55$ SY 184 10,120$ 184 10,120$ 184 10,120$ 184 10,120$ 184 10,120$ 184 10,120$ 184 10,120$ 184 10,120$
6 Structure Surveying 5,000$ LS 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$
7 Roadway Surveying 5,000$ LS 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$
8 As-bult Survey and Record Drawings 5,000$ LS 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$ 1 5,000$
9 Work Access (stream)50,000$ LS 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$
10 TESC Measures (5% of total)LS 1 219,525$ 1 234,127$ 1 280,083$ 1 252,583$ 1 221,734$ 1 239,916$ 1 283,031$ 1 255,531$
SUB-TOTAL 770,740$ 811,046$ 948,914$ 866,414$ 777,367$ 828,412$ 957,759$ 875,259$
EARTHWORK AND SURFACING
11 Roadway Excavation, incl. Haul 55$ CY 359 19,745$ 359 19,745$ 359 19,745$ 359 19,745$ 385 21,175$ 385 21,175$ 385 21,175$ 385 21,175$
12 Rock Excavation 1,000$ CY 485 485,000$ 649 649,000$ 485 485,000$ 485 485,000$ 485 485,000$ 649 649,000$ 485 485,000$ 485 485,000$
13 Structure Excavation Class A incl. Haul 60$ CY 15,371 922,260$ 15,105 906,300$ 8,362 501,720$ 8,362 501,720$ 15,382 922,920$ 15,311 918,660$ 8,440 506,400$ 8,440 506,400$
14 Channel Excavation Incl. Haul 100$ CY 600 60,000$ 600 60,000$ 600 60,000$ 600 60,000$ 600 60,000$ 600 60,000$ 600 60,000$ 600 60,000$
15 Dewatering 20,000$ LS 1 20,000$ 1 20,000$ 1 20,000$ 1 20,000$ 1 20,000$ 1 20,000$ 1 20,000$ 1 20,000$
16 Streambed Sediment 100$ Ton 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$
17 Streambed Sand 200$ Ton 80 16,000$ 80 16,000$ 80 16,000$ 80 16,000$ 80 16,000$ 80 16,000$ 80 16,000$ 80 16,000$
18 Streambed Cobbles 100$ Ton 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$ 720 72,000$
19 Streambed Boulder Type 1 150$ EA 300 45,000$ 300 45,000$ 300 45,000$ 300 45,000$ 300 45,000$ 300 45,000$ 300 45,000$ 300 45,000$
20 Compost 50$ CY 100 5,000$ 100 5,000$ 100 5,000$ 100 5,000$ 100 5,000$ 100 5,000$ 100 5,000$ 100 5,000$
21 Crushed Surfacing Base Course 60$ Ton 501 30,060$ 501 30,060$ 146 8,760$ 146 8,760$ 534 32,040$ 534 32,040$ 154 9,240$ 154 9,240$
22 Gravel Borrow 30$ Ton 27,100 813,000$ 25,200 756,000$ 1,400 42,000$ 1,400 42,000$ 27,800 834,000$ 26,600 798,000$ 1,700 51,000$ 1,700 51,000$
23 HMA CL. 1/2 IN. PG 58H-22 200$ TN 215 43,000$ 215 43,000$ 63 12,600$ 63 12,600$ 232 46,400$ 232 46,400$ 67 13,400$ 67 13,400$
24 Cement Conc. Sidewalk 150$ SY 288 43,200$ 288 43,200$ 58 8,700$ 58 8,700$ 292 43,800$ 292 43,800$ 65 9,750$ 65 9,750$
SUB-TOTAL 2,646,265$ 2,737,305$ 1,368,525$ 1,368,525$ 2,675,335$ 2,799,075$ 1,385,965$ 1,385,965$
STRUCTURE
25
3-Sided Conc. Box Culvert incl. footings,
stemwalls, headwalls and wingwalls 1,102,500$ LS 1 1,102,500$ - -$ - -$ - -$ 1 1,117,605$ - -$ - -$ - -$
26
Steel Plate Arch Culvert incl. footings and
wingwalls 1,307,000$ LS - -$ 1 1,307,000$ - -$ - -$ - -$ 1 1,361,000$ - -$ - -$
27 Bridge w/ SS on own bridge 3,594,899$ LS - -$ - -$ 1 3,594,899$ - -$ - -$ - -$ 1 3,636,426$ - -$
28 Bridge w/ SS on structure 3,044,899$ LS - -$ - -$ - -$ 1 3,044,899$ - -$ - -$ - -$ 1 3,086,426$
SUB-TOTAL 1,102,500$ 1,307,000$ 3,594,899$ 3,044,899$ 1,117,605$ 1,361,000$ 3,636,426$ 3,086,426$
UTILITIES
26 Adjust Catch Basin 800$ Each 1 800$ 1 800$ 1 800$ 1 800$ 1 800$ 1 800$ 1 800$ 1 800$
27 Drain Pipe, 12" Diam.30$ LF 69 2,070$ 69 2,070$ 69 2,070$ 69 2,070$ 69 2,070$ 69 2,070$ 69 2,070$ 69 2,070$
28 Temporary Utility Relocations 100,000$ LS 1 100,000$ 1 100,000$ 1 100,000$ 1 100,000$ 1 100,000$ 1 100,000$ 1 100,000$ 1 100,000$
SUB-TOTAL 102,870$ 102,870$ 102,870$ 102,870$ 102,870$ 102,870$ 102,870$ 102,870$
TRAFFIC
29 Temporary Traffic Control (3% of total)LS 1 131,715$ 1 140,476$ 1 168,050$ 1 151,550$ 1 133,040$ 1 143,949$ 1 169,819$ 1 153,319$
30 Paint Line 3$ LF 401 1,203$ 401 1,203$ 401 1,203$ 401 1,203$ 401 1,203$ 401 1,203$ 401 1,203$ 401 1,203$
31 Permanent Signing 1,500$ LS 1 1,500$ 1 1,500$ 1 1,500$ 1 1,500$ 1 1,500$ 1 1,500$ 1 1,500$ 1 1,500$
SUB-TOTAL 134,418$ 143,179$ 170,753$ 154,253$ 135,743$ 146,652$ 172,522$ 156,022$
HABITAT AND LANDSCAPE
32 Riparian Restoration 200,000$ AC 1 200,000$ 1 200,000$ 1 200,000$ 1 200,000$ 1 200,000$ 1 200,000$ 1 200,000$ 1 200,000$
33 Temporary Stream Diversion 50,000$ LS 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$ 1 50,000$
34 Log Structure 6,000$ EA 29 174,000$ 29 174,000$ 29 174,000$ 29 174,000$ 29 174,000$ 29 174,000$ 29 174,000$ 29 174,000$
SUB-TOTAL 424,000$ 424,000$ 424,000$ 424,000$ 424,000$ 424,000$ 424,000$ 424,000$
CONSTRUCTION COST SUBTOTAL 5,180,794$ 5,525,401$ 6,609,961$ 5,960,961$ 5,232,920$ 5,662,009$ 6,679,542$ 6,030,542$
CONTINGENCY 40.0% 2,072,317$ 40.0% 2,210,160$ 40.0% 2,643,984$ 40.0% 2,384,384$ 40.0% 2,093,168$ 40.0% 2,264,804$ 40.0% 2,671,817$ 40.0% 2,412,217$
SALES TAX 10.1%732,564$ 10.1%781,292$ 10.1%934,649$ 10.1%842,880$ 10.1%739,935$ 10.1%800,608$ 10.1%944,487$ 10.1%852,719$
ESTIMATED TOTAL CONSTRUCTION COST W/CONTINGENCY & SALES TAX 7,985,675$ 8,516,853$ 10,188,594$ 9,188,226$ 8,066,023$ 8,727,421$ 10,295,846$ 9,295,478$
Alternative 1a
Pre-Cast Concrete Box
Item#Item Description
Alternative 1c.1
Bridge w/ SS on own Bridge
Alternative 2c.1
Bridge w/ SS on own Bridge
Alternative 2c.2
Bridge w/ SS on Structure
Alternative 2a
Pre-Cast Concrete Box
Alternative 1b
Steel Plate Arch
Alternative 2b
Steel Plate Arch
Alternative 1c.2
Bridge w/ SS on Structure
GeoEngineers KPFF Conceptual Design Alternatives Page 1