APPROVED STM RESUB1 BLD2022-0746+Storm_Drainage_Report+10.6.2022_2.10.26_PM+3150892RAM Engineering BLD2022-0746
Memorandum
To: City of Edmonds RESU B Date: June 6, 2022
Engineering Division Oct 06 2022 Updated: October 6, 2022
From: Rob Long, PE DE EILO MF NDTSOERVCES
DEPARTMENT
RAM Engineering
Subject: Select Homes Lot 2- 8929 220th St SW Short Plat
Stormwater Memo
RAM Job No. 20-016
This memo provides a summary of the stormwater drainage control system for Lot 2 of the 8929 220th St SW
Short Plat (PLN 2021-038). A site -specific geotechnical evaluation recommends one stormwater BMP for the
site; BMP T5.13: Post -Construction Soil Quality and Depth based on the site's soil conditions. In accordance
with Edmonds Code, lawn and landscape areas will be managed by post -construction soil quality and depth
(soil amendments). The roof top, driveway, walk and patio areas will be managed by a detention pipe designed
in accordance with the Edmonds Stormwater Addendum. Additionally, a 10 ft (min.) footing drain drywell
trench shall be installed with the house construction to disperse footing drain water. The footing drain drywell
trench shall be installed and evaluated during construction by the geotechnical engineer.
The Lot 2 roof, driveway, walk and patio of 4,302 sf hard surface will require 35 ft of 36" pipe (4,302 sf x 0.008)
for BMP mitigation. The detention pipe will be constructed under the driveway area east of the proposed
house as part of the short plat site improvements.
Below is a stormwater control summary table for Lot 2:
Stormwater Control Summary:
Project Site Category: Category 2 (part of the 8929 2201h St SW 2-Lot Short Plat)
Discharge Location: City's Municipal Separate Storm Sewer System (MS4)
Type of Area
Square Footage
Storm water Facility
Lawn and Landscape
4,729 sf
Soil Amendments (BMP T5.13)
8,519 sf
Tree Retention Area
Roof
2,617 sf
Detention Pipe (ECDC 18.30.030.D.5.d)
35 ft of 36" pipe (4,302 sf x 0.008)
Hard Surfaces
1,225 sf
Detention Pipe (ECDC 18.30.030.D.5.d)
(Driveway/Apron, Walk and Patio)
26 ft of 24" pipe (4,302 sf x 0.008)
25% Retrofit
0 SF
None
P M Engineering 19109 36" Ave W, Suite 100 Lynnwood WA 98036 (425) 678-6960 RAMengineeringinc.com
Select Homes Lot 2- 8929 2001h ST SW Short Plat
Lot 2 Stormwater Memo
RAM Job No. 20-016
Select Homes 220th St SW Short Plat Lot 2 Hard Surface Summary:
Roof = 2,617 sf
Driveway = 1,175 sf
Sidewalk/Patio = 50 sf
Total = 4,302 sf
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Roof = 2,617 SF
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PROPOSED HOUSE
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RETAINING WALL TO BECONSTRUCFED
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PLAT (PLN2021-0038)
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Page 2 of 3
October 6, 2022
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WALK= 50 SF
CONNECT TO STUB
V�STQRM
IF 4,31,1t
5• ��ti
1NSTilLL 1-1/2" PE (160 PSI)
FROM WATER METER TO HOUSE
DETAILS. (TRACER WIRE TO 6E
�i
INSTALLED WITH WATER LINE)
SLOPE DRIVEWAY TO
CHANNEL DRAIN
,---(SEE SHEET 7P-01)
CHANNEL DRAIN
TOP 434.35
NOS PRO CHANNEL DRAIN
OR APPROVED EQUAL
(SEE DETAIL ON SHT GN--01)
DRIVEWAY = 1,175 SF
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r -41ORT PLAT IMPROVEMENTS
Tp BE CONSTRUCTED AS
i PART OF 77-IE 2207H ST SW
SIORT PLAT (PLNm21-oam)
RAM ^ngineering 1910936`1Ave W,Suite 100 Lynnwood WA 98036 (425)678-6960 RAMengineeringinc.com
Select Homes Lot 2- 8929 2001h ST SW Short Plot
Lot 2 Stormwater Memo
RAM lob No. 20-016
SOLID LOCKING LID
EL. 435.Of
EMER OF 431.69
6" PVC
RESTRICTOR
6" PVC
!E 428.50
1 ' MIN
CS 48" - TYPE II
SOLID LOCKING LID
EL. 434.50t
35 -36" CPEP
® 0.5OX MIN
DETEN710N
TANK
2'-8" CPEP STUB
CONNEC77ON ® 0.5%
PVC CAP ON 607TOM WI7H 0.5" ORIFICE
(SEE COAINEC77ON & CONTROL DEVICE
DETAIL THIS SHEET)
Page 3 of 3
October 6, 2022
8"IE 431.02
CB TYPEI
LOT 2 - DETENTION SYSTEM DETAIL
NOT TO SCALE
DETENTION SYSTEM SIZING
36" DE7EN77ON PIPE REQUIRED
4, 302 X 0.008 = 34.42LF REQ'D (35LF 36" PIPE PROPOSED)
(PER EDMONDS STORM WATER ADDENDUM 6.3.1)
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p. p JoAnne Zu(au{, rEM Tech 2123123
Stormwater Engineer Date
Taylor Brown, PE Blueline Group
Complies with City of Edmonds Stormwater Code
RAM Engineering 1910936 th Ave W, Suite 100 Lynnwood WA 98036 (425)678-6960 RAMengineeringinc.com