APPROVED STM BLD2021-0288+Storm_Drainage_Report+2.23.2021_3.29.42_PM+2060649RAM Engineering
To: City of Edmonds
Engineering Division
From: Rob Long, PE
RAM Engineering
Subject: Select- 8805 220th St SW Short Plat- Lot 3
Stormwater Memo
RAM Job No. 19-026
RECEIVED
Mar 12 2021
CITY OF EDMONDS
DEVELOPMENT SERVICES
DEPHRTMENT
Memorandum
Date: February 16, 2021
APPLIES WITH APPLICABLE
CITY STORMWATER CODE
This memo provides a summary of the stormwater hard surface allocation for Lot 3 of the Select- 8805 220th
St SW Short Plat (PLN 2020-0009). A site -specific geotechnical evaluation only recommends two possible
stormwater BMPs for the site; perforated stub -out connection 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 shared detention tank system has been designed as part of the short plat development and thus includes
hard surface areas allocated for each individual lot (see Select 220t" St SW Short Plat Stormwater Site Plan
Report). Lot 3 has an allocation of 4,161 sf of impervious/hard surface, which include roof, driveway, and
patio/walkway areas.
Below is a stormwater control summary table for Lot 3:
Lot 3 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
Stormwater Facility
Lawn and Landscape
5,148 sf
Soil Amendments (BMP T5.13)
Roofs
2,661 sf
Detention Tank
Hard Surfaces
1,500 sf
Detention Tank
25% Retrofit
0 SF
None
2116/ZOZ 1
Select- 8805 220th St SW Short Plat- Lot 3
Stormwater Memo
RAM lob No. 19-026
Page 2 of 2
Select 8805 220t" St SW Short Plat Lot 3 Hard Surface Summary:
Roof = 2,661 sf
Driveway = 100 sf
Patio/Walk = 1,400 sf
Total = 4,161 sf
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