APPROVED Purser SP Lot 2- Drainage Memo 2020-06-09RAM Engineering
RECEIVED 6/10/20
To: City of Edmonds
Engineering Division
From: Rob Long, PE
RAM Engineering
Subject: Purser Short Plat- Lot 2
Stormwater Memo
RAM Job No. 19-014
Memorandum
Date: June 9, 2020
COMPLIES WITH APPLICABLE
C DE
This memo provides a summary of the stormwater hard surface allocation for Lot 2 of the Purser Short Plat
(PLN 20190040). 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 infiltration trench 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 2 has
an allocation of 3,700 sf of impervious/hard surface, which include roof, driveway, patio and walkway areas.
Below is a stormwater control summary table for Lot 2:
Stormwater Control Summary:
Project Site Category: Category 2 (part of the Purser Short Plat)
Discharge Location: City's Municipal Separate Storm Sewer System (MS4)
Type of Area
Square Footage
Stormwater Facility
Lawn and Landscape
4,838 sf
Soil Amendments (BMP T5.13)
Roofs
2,835 sf
Detention Vault
Hard Surfaces
1,165 sf
Detention Vault
25% Retrofit
0 SF
None
Purser Short Plat- Lot 2
Stormwater Memo
RAM lob No. 19-014
Page 2 of 2
Purser Short Lot 2 Hard Surface Summary:
Roof = 2,535 sf
Driveway = 1,065 sf
Sidewalk/Patio = 100 sf
Total = 3,700 sf
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RAM Engineering 165311311 Ave W, Suite A108 Lynnwood WA 98037 (425)678-6960 RAMengineeringinc.com