APPROVED STM BLD2020-1177+Storm_Drainage_Report+10.30.2020_10.20.22_AMRAM Engineering
RECEIVED Memorandum
Nov 05 2020
To: City of Edmonds
Engineering Division
From: Rob Long, PE
RAM Engineering
CITY OF EDMONDS
DEVELOPMENT SERVICES
DEPARTMENT
Subject: Select- 8805 220th St SW Short Plat- Lot 1
Stormwater Memo
RAM Job No. 19-026
Date: October 29, 2020
COMPLIES WITH APPLICABLE
CITY CTr10RA1A/ATG0r`r%nE
This memo provides a summary of the stormwater hard surface allocation for Lot 1 of the Select- 8805 220th
St SW Short Plat (PLN 2020-0009). A site -specific geotechnical evaluation recommends two stormwater BMPs
for the site; Infiltration and BMP T5.13: Post -Construction Soil Quality and Depth. Project impervious/hard
surface (roof, driveway, walk/patio areas) will be managed by a shared stormwater detention tank system
with the short plat development.
The infiltration trench system has been designed as part of the short plat development and thus includes hard
surface areas allocated for each individual lot (see Purser Short Plat Stormwater Site Plan Report). Lot 1 has
an allocation of 3,201 sf of impervious/hard surface, which include roof, driveway, and patio/walkway areas.
Below is a stormwater control summary table for Lot 1:
Stormwater Control Summary:
Project Site Category: Category 2 (part of the Select- 8805 220th St SW Short Plat)
Discharge Location: City's Municipal Separate Storm Sewer System (MS4)
Type of Area
Square Footage
Storm water Facility
Lawn and Landscape
5,660 sf
Soil Amendments (BMP T5.13)
Roofs
2,501 sf
Detention Vault
Hard Surfaces
700 sf
Detention Vault
25% Retrofit
0 SF
None
Select- 8805 220th St SW Short Plat- Lot 1 Page 2 of 2
Stormwater Memo
RAM Job No. 19-026
Purser Short Lot 1 Hard Surface Summary:
Roof = 2,501 sf
Driveway = 650 sf
Patio/Walk = 50 sf
Total = 3,201 sf
/o/29/2O2O
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