APPROVED STM BLD2021-1103+Storm_Drainage_Report+8.9.2021_11.30.01_AM+2346411RECEIVED
RAM Engineering 8-13-21
To: Cityof Edmonds CITY OF EDMONDS
DEVELOPMENT
Engineering Division SERVICES DEPARTMENT
From: Rob Long, PE
RAM Engineering
Subject: Adamant Homes, Inc. - 240th St SW Short 1
Stormwater Memo
RAM Job No. 19-015
BLD2021-1103
Memorandum
Date: August 5, 2021
OMPLIES WITH APPLICABLE
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This memo provides a summary of the stormwater hard surface allocation for Lot 4 of the Adamant Homes
240th St SW Short Plat (PLN 2019-0052). 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 Adamant 240t" St SW Short Plat Stormwater Site Plan
Report). Lot 4 has an allocation of 4,450sf of impervious/hard surface, which include roof, driveway, and
patio/walkway areas.
Below is a stormwater control summary table for Lot 4:
Stormwater Control Summary:
Project Site Category: Category 2 (part of the Adamant - 240th 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
8,993sf
Soil Amendments (BMP T5.13)
Roofs
2,368 sf
Detention Vault
Hard Surfaces
1,780 sf
Detention Vault
25% Retrofit
0 SF
None
Adamant Homes, Inc. - 240th St SW Short Plat- Lot 4
Stormwater Memo
RAM lob No. 19-015
Page 2 of 2
240th St SW Short Plat Lot 4 Hard Surface Summary:
Roof = 2,368 sf
Driveway = 1,750 sf
Patio/Walk = 30 sf
Total = 4,148 sf
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