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Public Works Department
SE 172ND ST WATER QUALITY RETROFIT PROJECT
PROJECT NARRATIVE
Size:
4.86 acres
Location:
SE 172nd St from 122nd Ave SE to 125th Ave SE; 122nd Ave SE, 123rd Ave SE, 124th Ave SE, and 125th
Ave SE from SE 172nd St to SE 169th Pl
Zoning Designation of Site and Adjacent Properties:
The existing zoning is residential streets in public right-of-way, with Residential 6 du/ac (R-6) for adjacent
properties.
Current Use of Site and Any Existing Improvements:
The site is currently being used as for single-family residential street traffic. The site will be improved with
porous concrete sidewalk, new stormwater pipes and structures, and water quality treatment facilities.
Special Site Features:
None.
Statement Addressing Soil type and Drainage Conditions:
USDA and NRCS soils data show that soils in project area are in hydrologic soil group B/D. In general, the
soils have higher permeability near the surface with lower permeability till starting at a depth of 1 to 5 feet
below the surface. The depth to groundwater is typically 4 to 6 feet below the surface. Due to shallow road
slopes and insufficient catch basins and curbs, the site has a history of poor drainage of stormwater runoff
along the roadway. Currently stormwater runoff from SE 172nd St, 122nd Ave SE, 123rd Ave SE, 124th
Ave SE, and 125th Ave SE is collected and conveyed into a storm system on SE 172nd St.
Proposed Use of the Property and Scope of the Proposed Development:
The Project will retrofit the neighborhood streets by installing a new conveyance system, pervious concrete
sidewalks, and stormwater biofiltration systems with Ecology TAPE GULD approval for enhanced water
quality treatment. The project area is entirely within public right-of-way and is comprised of paved streets
without existing curb, gutter, or sidewalk. Land disturbance of the site, including excavation and paving, is
roughly 65,000 square feet within the public right-of-way. Construction activities occur along roughly
3,600 linear feet of roadway, where the right-of-way width ranges from 50 feet on the cross streets to 60
feet on SE 172nd St.
Access:
Vehicles will likely enter and leave the site from SE 172nd St, to 128th Ave SE, to SE Petrovitsky Rd.
Access to the site is also available from SE 168th St.
Proposed Off-Site Improvements:
None.
Public Works Department
Total Estimated Construction Cost/Estimated Fair Market value of Proposed Project:
$3,290,300.
Estimated Fair Market Value of Proposed Project:
N/A
Estimated Quantities and Type of Materials Involved in Fill or Excavation:
Total Fill: 5,765 CY consisting of:
· 175 CY of controlled density fill
· 1,270 CY of CSTC
· 1,270 CY of HMA
· 2,430 CY gravel borrow for trench backfill
· 620 CY pervious cement concrete sidewalk
Total Excavation: 6,020 CY consisting of:
· 120 CY of removal and replacement of unsuitable foundation excavation
· 5,900 CY of structure excavation class B
Number, Type and Size of Any Trees to be Removed:
12” Birch (122nd Ave SE)
16” Birch (122nd Ave SE)
16” Fir (Intersection of 125th Ave SE & SE 172nd St)
18” Pine x3 (Intersection of 125th Ave SE & SE 172nd St)
Explanation of Any Land to be Dedicated to the City:
None
Any Proposed Job Shacks, Sales Trailers, and/or model Homes:
N/A
Any Proposed Modifications Being Requested:
None
Is Project Within 100 ft of a Stream or Wetland:
Yes. Approximately 150 feet south of the intersection of 127th Ave SE and SE 172nd Street, the stormwater
system discharges into a category II depressional wetland (Wetland A).
Is Project within 200 ft of Black River, Cedar River Springbrook Creek, May Creek and Lake
Washington:
No