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Public Works Department
MONROE AVE NE INFILTRATION FACILITY
PROJECT NARRATIVE
Size:
3.00 acres
Location:
301 Monroe Ave NE, Renton, WA
Zoning Designation of Site and Adjacent Properties:
The existing zoning is Residential 10 du/ac (R-10).
Current Use of Site and Any Existing Improvements:
The site is currently being used as a gravel pit and contains no existing improvements. The site currently
receives untreated stormwater runoff from a 245-acre subbasin via drainage overflow pipes in Monroe
Ave NE. Runoff ponds onsite and infiltrates into the soil.
Special Site Features: Site contains temporary steep slopes that will be protected during construction.
Statement Addressing Soil type and Drainage Conditions:
In the location where the infiltration facility is proposed, the soil is highly permeable glacial outwash with
a conservative design infiltration rate of 20 inches per hour. In locations where the infiltration facility is not
proposed, the soil is fill comprising of silty sand, sand with gravel, and crushed rock. The site currently
receives untreated stormwater runoff from a 245-acre subbasin via drainage overflow pipes in Monroe Ave
NE. Runoff ponds onsite and infiltrates into the soil.
Proposed Use of the Property and Scope of the Proposed Development:
The project will provide flow control and water quality treatment of stormwater runoff for the 245-acre
subbasin via new treatment and infiltration facilities. The bulk of project improvements consist of
underground stormwater facilities, pipes, and structures that will reside below the new 14,300 SF
maintenance access road and large grass field area. All permanent improvements to the project site itself
will be located within the 3.00-acre permanent utility easement. The permanent utility easement will
allow the City to access and maintain the new stormwater facilities from Monroe Ave NE in perpetuity.
Access:
Access to site can be achieved from Monroe Ave NE or Jefferson Ave NE.
Proposed Off-Site Improvements:
Offsite improvements on Monroe Ave NE will be minor, including light pole replacement, pavement
restoration, stormwater pipe connection, and limited construction of sidewalk, driveway, and curb and
gutter.
Public Works Department
Total Estimated Construction Cost/Estimated Fair Market value of Proposed Project:
Total Estimated Construction Cost: $16,496,000 before tax and $18,162,000 after tax.
Estimated Fair Mark Value of Proposed Project:
N/A
Estimated Quantities and Type of Materials Involved in Fill or Excavation:
Fill quantities include roughly 42,700 CY of non-infiltration material, 800 CY of CSTC, 21,000 CY of
select borrow, 59,100 CY of infiltration gravel, 6,000 CY of gravel borrow, 2,400 CY of gravel backfill for
walls, 10,100 CY of topsoil, and 600 CY of mulch.
Excavation quantities include roughly 1,700 CY of unclassified excavation.
Number, Type and Size of Any Trees to be Removed:
None
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:
No
Is Project within 200 ft of Black River, Cedar River Springbrook Creek, May Creek and Lake
Washington:
No