APPROVED STM BLD2021-1719+Storm_Drainage_Report+12.21.2021_1.17.00_PM+2586037RECEIVED
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RAM Engineering Dec 28 2021
CITY OF EDMONDS
DEVELOPMENT SERVICES
DEPARTMENT
To: City of Edmonds BLD2021-171
Engineering Division LOT 2
From: Rob Long, PE
RAM Engineering
Subject: Select Homes 2-Lot Short Plat at 7918 203rd St
Lot 2 Stormwater Memo
RAM Job No. 20-020
Memorandum
REVIEWED
BY
CITY OF EDMONDS
LN2021-0039)- Lot 2
This memo provides a summary of the stormwater drainage control system for Lot 2 of the Select Homes 2-Lot
Short Plat at 7918 203rd St SW(PLN2021-0039). A site -specific geotechnical evaluation recommends infiltration
as the stormwater control measure, in addition, BMP T5.13: Post -Construction Soil Quality and Depth shall be
applied to all disturbed pervious areas of the project site. The proposed roof top and "other hard surfaces"
(driveway, patio, walks, etc.) will be managed by joint (Lot 1 and 2) infiltration trench located under the shared
driveway for the project.
The joint infiltration trench has been designed to account for both Lot 1 and Lot 2 hard (impervious) surfaces of
the short plat; the infiltration system design accommodates 3,950 sf of hard surface from Lot 2 (per Short Plat
Civil Design). The proposed hard surface of Lot 2 consists of 2,800 sf of roof area, 1,100 sf driveway, and 50 sf
of uncovered walk and patio.
Below is a stormwater control summary table for Lot 2:
Stormwater Control Summary:
Project Site Category: Category 2 (part of the 203rd St SW 2-Lot Short Plat)
Discharge Location: On -site Infiltration
Type of Area
Square Footage
Stormwater Facility
Lawn and Landscape
8,991 sf
Soil Amendments (BMP T5.13)
Roof
2,800 sf
Infiltration Trench
Hard Surfaces
1,150 sf
Infiltration Trench
(Driveway, Walk and Patio)
25% Retrofit
0 SF
None
COMPLIES WITH APPLICABLE
CITY STORMWATER CODE
,�2/3/2022
RAM Engineering
19109 36" Ave W, Suite 100 Lynnwood WA 98036 (425) 678-6960 RAMengineeringinc.com
Select Homes 2-Lot Short Plat at 7918 203'd St SW- Lot 2
Stormwater Memo
RAM lob No. 20-020
Select Homes 203rd St SW Short Plat Lot 2 Hard Surface Summary:
Roof = 2,800 sf
Driveway = 1,100 sf
Sidewalk/Patio = 50 sf
Total = 3,950 sf
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VOL. 17 PG. 70
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(425) 678-6960 RAMengineeringinc.com