HomeMy WebLinkAboutRS_StreamAssessmentReport_251209_v1Memorandum
1145 Broadway, Suite 300, Tacoma, Washington 98402, Telephone: 253.383.4940 www.geoengineers.com
To: Kathryn Hodges; Puget Sound Energy
From: Jennifer Dadisman, PWS and Joe Callaghan, PWS; GeoEngineers, Inc.
Date: December 9, 2025
File: 9186-184-00, Task 2032
Subject: Stream Assessment at the SWARR Station
Introduction
GeoEngineers, Inc. (GeoEngineers) was contracted by Puget Sound Energy (PSE) to perform stream
assessment services at their SWARR Station facility located at 2100 Benson Drive South in Renton,
Washington (Figure 1, Vicinity Map). The project site is located on a portion of one parcel (Parcel
No. 2023059071) that is approximately 16.7 acres in size. The project site was developed by Washington
Natural Gas (now Puget Sound Energy) in 1965 as a “peak shaving” facility for periods of high natural gas
demand during cold weather. A stream (Rolling Hills Creek) flows north through a culvert under the center
of the property. Figure 2, Fence Replacement Site Plan, depicts the site plan for the project and stream
location identified during the site visit. This report has been prepared to provide baseline stream habitat
information on the project site in accordance with Renton Municipal Code (RMC) Chapter 3 Environmental
Regulations and Overlay Districts; Section 4-3-050 Critical Areas Regulations.
Project Description
PSE is proposing to replace the existing 6-foot-tall chain link fence around the SWARR Station with a new
8- to 12-foot-tall Tier 2 metal mesh fence including intrusion detection and security cameras to meet State
and Federal Code and PSE standards. PSE also plans to replace the aging vehicle and pedestrian gates at
the main entrance to Benson Drive South in the southwest corner of the site and at the back entrance to
South Puget Drive in the northeast corner of the site. The replacement fence alignment will generally follow
existing fence alignment, with some segments shifting further into developed areas. The fence will not move
outward away from the developed station footprint. The security system will be updated to current
technology, with new security cameras and associated conduit and electrical system adjustments. The
security system equipment will be attached to the fence or fence posts. Associated electrical and
communication system modifications will be either attached to the fence, or installed via trenching, or
horizontal directional drilling (HDD). Minor excavation, including augering or hydro-vactoring, for fence and
camera post installation, will also occur as part of the project. Refer to the Project Narrative and project
site plan (prepared by PSE) for more detailed information on the proposed work.
Site Description
The SWARR Station is located on an approximately 16.7-acre parcel; with the developed portion of the site
occupying the south 8 acres of the property. The proposed fence, gate and security maintenance will take
place within the developed portion of the site only and will not extend to the undeveloped areas of the
parcel. The property is bordered to the north by forested habitat and Benson Road South, to the east by
Memorandum to Kathryn Hodges; Puget Sound Energy
December 9, 2025
Page 2
businesses and South Puget Drive, to the south by single-family homes and to the west by Benson Drive
South, the PSE Seattle South Gate Station, tennis courts and single-family homes. The property is located
within Section 20 of Township 23 North and Range 05 East of the Willamette Meridian (WM).
The fenced southern portion of the property, which includes the developed area, contains forested habitat
with little understory vegetation around the edges of the improved area and maintained grass over the
remaining areas. The northern portion of the parcel (outside of the fenced facility) is undeveloped and
forested with shrub understory. Figure 2 provides a site overview of the parcel.
STORMWATER FACILITIES
According to the City of Renton Utility Geographic Information System (GIS) data (City of Renton 2024),
there are multiple stormwater discharge points that direct water towards the SWARR Station parcel from
offsite roadways and parking lots. In the northwest corner of the developed station project area, there is
evidence of water sheet flowing from the discharge point and flowing northeast through the fence line
towards Rolling Hills Creek. In the southeast corner of the developed project site, a discharge point from
South Puget Drive directs water westward where a virtual drainage path is mapped by the City of Renton,
towards Rolling Hills Creek. However, due to natural topography, water does not directly enter the stream
and evidence of standing water was observed just east of the south portion of the site where Rolling Hills
Creek enters the culvert. A ditch extends north/south along the east side of the property at the base of the
slope and collects stormwater from the discharge points above on South Puget Drive. The ditch directs
water south towards Rolling Hills Creek. Figure 2 displays these stormwater discharge points.
Field Investigation and Site Observations
METHODS
Assessment of streams was conducted in accordance with guidelines presented in RMC Chapter 3
Environmental Regulations and Overlay Districts; Section 4-3-050 Critical Areas Regulations. Streams were
evaluated by examining breaks in the topography, shifts in vegetation and accumulation of wrack and other
flood debris, in accordance to United States Army Corps of Engineers (USACE) protocol as referenced in the
National Ordinary High Water Mark Field Delineation Manual for Rivers and Streams Final Version, January
2025 (David et al. 2025) and according to the Washington State Department of Ecology (Ecology) 2016
guidance (Anderson et al. 2016). The Washington Administrative Code (WAC) was also referenced for the
definition of ordinary high water mark (OHWM) (WAC 173.22.030 § 11).
RESULTS
Biologists conducted a field assessment on September 27, 2024, to document stream habitat conditions
on the site. Representative photographs of the site have been included in Appendix A, Site Photographs.
One stream (Rolling Hills Creek) is mapped as flowing through the site but is located within a culvert under
the property. GeoEngineers’ biologists delineated the OHWM for the southern portion of the daylighted
Rolling Hills Creek channel; Light Detection and Ranging (lidar) was used to identify the OHWM for the
daylighted northern portion of the creek because it is outside the project site.
Memorandum to Kathryn Hodges; Puget Sound Energy
December 9, 2025
Page 3
Rolling Hills Creek was observed flowing into the culvert inlet at the south end of the project site and
discharging to an open stream channel at the north end of the project site. Since there is no stream channel
through the property and no evidence of water flow, it is assumed that there is no stream buffer associated
with the creek through the center of the property. The Creek is mapped as a fish-bearing stream and the
daylighted portions of the channel will have a 115-foot buffer (RMC Chapter 3, Section 4-3-050 (G)
[Development Standards]).
Potential Project Impacts
There should be no permanent impacts as a result of installing the replacement fence. The fence at the
north end of the property, adjacent to the Rolling Hills Creek daylighted stream channel will be placed in
the existing fence location which is on top of the existing culvert outlet. The fence in the south portion of
the site, adjacent to where Rolling Hills Creek enters the underground culvert, will be located upslope of
the culvert, within existing rock and gravel that is adjacent to the existing paved road. This portion of the
fence line is outside the stream buffer. The existing fence at the south end, is located further south than
the proposed location and crosses the open channel. The proposed fence location in the southern end will
eliminate the open channel crossing by moving the fence on top of the existing culvert. There will be no tree
or shrub removal from the portion of the stream buffer that extends over the project site.
There will be no impact to stream buffer as a result of replacing the fence in the north end of the project,
moving the fence in the south end of the project and installing poles for security cameras. The fence
alignment is outside the buffer and the area where the fence is adjacent to the stream does not provide
critical area functions or value; there will be no impacts to stream buffer functions or values as a result of
the project. Replacing the fence and installing the poles for security cameras likely qualifies as a facility
improvement which means the project may also qualify for an exemption according to 4-3-050C.3, item g i
in the table. This exemption states that “remodeling, replacing, removing Existing Structures, Facilities, and
Improvements” are exempt within streams and wetlands.
Summary
GeoEngineers performed stream assessment services at the PSE SWARR Facility property to provide
baseline stream habitat information for the proposed site exploration project. One stream (Rolling Hills
Creek) is mapped as flowing through the site but is located within a culvert under the property. Since there
is no stream channel through the property and no evidence of water flow, it is assumed that there is no
stream buffer associated with the creek through the center of the property. The creek is mapped as a
fish-bearing stream and the daylighted portions of the channel will have a 115-foot buffer. There will be no
impact to stream buffer as a result of replacing the fence in the north end of the project, moving the fence
in the south end of the project, and installing poles for security cameras because the fence alignment is
outside the buffer and the area where the fence is adjacent to the stream does not provide critical area
functions or value.
Memorandum to Kathryn Hodges; Puget Sound Energy
December 9, 2025
Page 4
Limitations
GeoEngineers has prepared this Stream Assessment Memorandum in general accordance with the scope
and limitations of our proposal. Within the limitations of scope, schedule and budget, our services have
been executed in accordance with the generally accepted practices for stream delineation in this area at
the time this report was prepared. No warranty or other conditions, express or implied, should be
understood.
This report has been prepared for the exclusive use of Puget Sound Energy, authorized agents and
regulatory agencies following the described methods and information available at the time of the work. No
other party may rely on the product of our services unless we agree in advance to such reliance in writing.
The information contained herein should not be applied for any purpose or project except the one originally
contemplated.
The applicant is advised to contact all appropriate regulatory agencies (local, state and federal) prior to
design or construction of any development to obtain necessary permits and approvals.
References
Anderson, Paul, S. Meyer, P. Olson and E. Stockdale. 2016. Determining the Ordinary High Water Mark for
Shoreline Management Act Compliance in Washington State. Washington State Department of
Ecology Publication No. 16-06-029. Available at: https://apps.ecology.wa.gov/
publications/documents/1606029.pdf
City of Renton. Renton Municipal Code, Title IV Development Regulations, Chapter 3, Environmental
Regulations and Overlay Districts, Section 4-3-050 – Critical Areas Regulations.
City of Renton. 2024. COR MAPS. Available at: https://maps.rentonwa.gov/Html5viewer/
Index.html?viewer=cormaps.
David, Gabrielle C. L., Ken M. Fritz, Tracie-Lynn Nadeau, Brian J. Topping, Aaron O. Allen, Patrick H. Trier,
Steven L. Kichefski, L. Allan James, Ellen Wohl, and Daniel Hamill. 2025. National Ordinary High
Water Mark Field Delineation Manual for Rivers and Streams: Final Version. Army Corps of
Engineers Engineer Research and Development Center. ERDC/CRREL TR-25-1
Washington State Administrative Code. 2007. WAC 173-22-030. Definitions. Available at:
http://apps.leg.wa.gov/WAC/default.aspx?cite=173-22-030.
Attachments:
Figure 1. Vicinity Map
Figure 2. Fence Replacement Site Plan
Appendix A. Site Photographs
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.
Figures
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Vicinity Map
Figure 1
SWARR Facility Fence Replacement
Renton, Washington
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Source(s):• ESRI
Coordinate System: NAD 1983 UTM Zone 10N
Disclaimer: This figure was created for a specific purpose and project. Any use of this figurefor any other project or purpose shall be at the user's sole risk and without liability to GeoEngineers.
The locations of features shown may be approximate. GeoEngineers makes no warranty orrepresentation as to the accuracy, completeness, or suitability of the figure, or data containedtherein. The file containing this figure is a copy of a master document, the original of which isretained by GeoEngineers and is the official document of record.
Stream EntersUnderground Culvert
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Fence Replacement Site Plan
SWARR Facility Fence Replacement
Renton, Washington
Figure 2
0 150
Feet
Legend
Rebuild Fence - Approximate
Location (2,133.3 feet)
Existing Fence (2,976.8 feet)
Parcel Boundary (731,015
square feet)
Culvert
Forested and Shrub Vegatation
Cover (506,838 square feet)
Pedestrian Gate and Vehicle
Entry
City Catch Basin
City Storm Drain
City Discharge Point
City Virtual Drainline
P:\9\9186184\GIS\9186184_2024_Q4\9186184_2024_Q4.aprx\918618400tsk2032_F02_SWARRFenceReplacement Date Exported: 12/03/25 by ccabrera
Notes:
1. No changes to parking or new buildings proposed
Source(s):• Drawing updated with proposed fence alignment 10/3/24.• Streams and critical areas obtained from City of Renton GIS, http://rentonwa.gov/government/.• Roads, 2015 aerial, contours and parcel boundaries from King County GIS. http://www.kingcounty.gov/services/gis.aspxCoordinate System: NAD 1983 HARN StatePlane Washington North FIPS 4601 Feet
Disclaimer: This figure was created for a specific purpose and project. Any use of this figure for any other project or purpose shall be at the user's sole risk and without liability toGeoEngineers. The locations of features shown may be approximate. GeoEngineers makes no warranty or representation as to the accuracy, completeness, or suitability of thefigure, 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 ofrecord.
Appendices
Appendix A
Site Photographs
Figure A-1
Photograph 1. At site entrance gate, looking east along entrance driveway and area to south of driveway.
Photograph 2. East of site entrance gate, looking east towards east slopes, existing and proposed fence location and Rolling
Hills Creek.
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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.
Site Entrance Driveway
Site Entrance Driveway and Shoulder
Existing Fence Line
Rolling Hills Creek
Site Photographs
SWARR Facility Fence Replacement
Renton, Washington
Figure A-2
Photograph 3. Looking north along Rolling Hills Creek in the south end of the project site.
Photograph 4. Rolling Hills Creek, looking south towards Rolling Hills Creek, culvert under site and outfall from South PugetDrive.
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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.
Outfall Flow Channel and standing
water from South Puget Drive
Rolling Hills Creek
Culvert Conveying
Rolling Hills Creek
under Project Site
Rolling Hills Creek
Culvert and trash rack
Proposed fence line
Site Photographs
SWARR Facility Fence Replacement
Renton, Washington
Figure A-3
Photograph 5. At southeast corner of project area, looking west towards Benson Drive South along site entrance driveway and Rolling Hills Creek.
Photograph 6. At southeast corner of project area and Rolling Hills Creek, looking east towards overflow half round.
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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.
Benson Drive South
Site Entrance Driveway
Rolling Hills Creek
and culvert inlet
Proposed Fence Line
Existing fence line
Overflow half-round
Rolling Hills Creek
and culvert inlet
Site Photographs
SWARR Facility Fence Replacement
Renton, Washington
Figure A-4
Photograph 7. On east side of site, looking north along driveway. Half-round culvert flows south towards Rolling Hills Creek.
Photograph 8. Northeast side of site, looking north along driveway.
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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.
Site entrance driveway
and shoulder
Slope drain outlet
Proposed fence line
Culvert that conveys
stormwater to north
side of site
Proposed fence line
Existing fence line
Half-round culvert and
flow direction
Half-round culvert and
flow direction
Slope up to South
Puget Drive
Site Photographs
SWARR Facility Fence Replacement
Renton, Washington
Figure A-5
Photograph 9. Slope drain and half-round culvert along east side of driveway, looking southeast towards slope.
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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.
Slope drain from South
Puget Drive
Half-round culvert and
flow direction
Site Photographs
SWARR Facility Fence Replacement
Renton, Washington
Photograph 10. At gravel walkway to building, looking northwest towards underground tank area north of building and along concrete swale.
Benson Drive South
Concrete drainage swale
Figure A-6
Photograph 11. Near north end of site looking south.
Photograph 12. Near north end of site looking southeast up slope towards South Puget Drive.
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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.
Half-round culvert
Site Entrance Driveway and Parking Area
Slope drain from
South Puget Drive
South Puget Drive
Existing fence line
Site Photographs
SWARR Facility Fence Replacement
Renton, Washington