HomeMy WebLinkAboutProject Narrative
DATE: May 15, 2025
TO: Jill Ding, Senior Planner
FROM: Betsy Severtsen, Capital Projects Manager
SUBJECT: Project Narrative: Springbrook Trail Boardwalk Replacement
Project Narrative: Springbrook Trail Boardwalk Replacement
1. Project Name, Size, and Location of Site:
Project Name: Springbrook Trail Boardwalk Repair
Site Size: The project affects approximately 100 linear feet of existing boardwalk
trail.
Location: Springbrook Creek Wetland and Habitat Mitigation Bank, City of Renton
2. Zoning Designation of the Site and Adjacent Properties:
The subject property is zoned as resource conservation/public open space.
Adjacent properties to the north and east are zoned for industrial uses and are
primarily composed of paved surfaces and buildings.
3. Current Use of the Site and Any Existing Improvements:
The site is currently used as a public greenspace and passive recreation area.
Access is provided via the Springbrook Trail Boardwalk, the only structure on the
property. Off-trail use is not permitted. The northernmost 100 feet of this boardwalk
was destroyed in a fire on April 15, 2023.
4. Special Site Features (Wetlands, Water Bodies, Steep Slopes):
The property is within the Springbrook Creek Wetland and Habitat Mitigation Bank, a
regulated wetland area. No steep slopes are present. The site is adjacent to
Springbrook Creek and contains Wetland A. Please see attached Critical Areas
Report.
5. Statement Addressing Soil Type and Drainage Conditions:
The site soils are seasonally saturated and consistent with wetland environments,
with poor natural drainage and hydric characteristics due to the presence of water-
tolerant vegetation and wetland hydrology. Geotechnical engineers visited the site
on June 20, 2024 to evaluate subgrade conditions. In the northern 45 feet of the
former boardwalk alignment, subgrade soils consisted of silty sand with gravel.
Probe depths in this area were on the order of 0 to 2 inches. In the southern 55 feet
of the alignment, soils appeared to consist of brown silty sand to sandy silt with
Springbrook Trail Boardwalk Replacement – Project Narrative
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May 15, 2025
noticeably increased moisture content. Probe depths in this area ranged between
18 and 30 inches. They interpreted site soils to be either fill or alluvial soils. They did
not observe peat-like soils in the project alignment. Please see attached
Geotechnical Design Report.
6. Proposed Use of the Property and Scope of Proposed Development:
The proposed project will restore public access to the existing greenspace by
reconstructing 100 linear feet of the Springbrook Trail Boardwalk. The replacement
structure will be elevated approximately 2–3 feet above the wetland surface and will
match the original in design and footprint. The boardwalk will consist of structural
plastic lumber decking and railings with welded wire mesh fence fabric.
a. Height: Approx. 2–3 feet above ground
b. Square Footage: Approx. 800 sq. ft.
c. Lot Coverage: No net increase in coverage
7. Parking & Access: No changes to parking or site access
8. Proposed Off-site Improvements:
None. No off-site improvements such as sidewalks, sewer mains, or fire hydrants
are proposed.
9. Total Estimated Construction Cost and Estimated Fair Market Value:
a. Estimated Construction Cost: $253,640
b. Estimated Fair Market Value: Equivalent to construction cost as no
additional improvements or value-generating structures are proposed.
10. Estimated Quantities and Type of Materials for Fill or Excavation:
Minimal fill is proposed. Approximately 30 precast concrete footings (1 cubic foot
each) will be placed on the ground with small-diameter steel pin piles used for
stabilization equating to a fill volume of approximately 27-30 cubic feet (or about 1
cubic-yard) of concrete.
11. Number, Type, and Size of Trees to be Removed:
No trees will be removed as part of this project.
12. Explanation of Any Land to be Dedicated to the City:
No land dedication is proposed.