APPROVED STM RESUB2 BLD2021-0070+DRAINAGE MEMO 5.25.2021_2.08.45_PM+2215999RAM Engineering
To: City of Edmonds
Engineering Division
From: Rob Long, PE
RAM Engineering
Subject: Select Homes Walnut Short Plat- Lot 2
Stormwater Memo
RAM Job No. 19-032
BLD2021-0070
RESUB Memorandum
May 26 2021
CITY OF EDMONDS
DEVELOPMENT SERVICES
DEPARTMENT
Date: May 25, 2021
COMPLIES WITH APPLICABLE
CITY STORMWATER CODE
This memo provides a summary of the stormwater hard surface allocation for Lot 2 of the Select Homes
Walnut Short Plat (PLN 2020-0033). A site -specific geotechnical evaluation recommends two stormwater
BMPs for the site; Infiltration and BMP T5.13: Post -Construction Soil Quality and Depth. Lot impervious/hard
surface (roof, driveway, walk/patio areas) will be managed by an individual lot infiltration trench system.
The infiltration trench system has been designed as part of the short plat development and includes dedicated
hard surface areas allocated for the individual lot (see Walnut Short Plat Stormwater Site Plan Report). Lot 2
has an allocation of 3,524 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 Walnut Short Plat)
Discharge Location: City's Municipal Separate Storm Sewer System (MS4)
Type of Area
Square Footage
Storm water Facility
Lawn and Landscape
2,664 sf
Soil Amendments (BMP T5.13)
Roofs
2,474 sf
Infiltration Trench
Hard Surfaces
1,000 sf
Infiltration Trench
25% Retrofit
0 SF
None
Select Homes Walnut Short Plat- Lot 2 Page 2 of 2
Stormwater Memo
RAM lob No. 19-032
Walnut Short Lot 2 Hard Surface Summary:
Roof = 2,474 sf
Driveway = 950 sf
Sidewalk/Patio = 50 sf
Total = 3,524 sf
II 1
SHORT PLAT IMPROVEMENTS 'II i / •L_-__ ____•
CONSTRUCTED AS PART OF
THE WALNUT SHORT PLAT ' \��gg'r' f�______----•
(PLN20200033) rT 999 III
ya ACCESS/ i µ�
I UTILITY i III F,
6" PVC STORM SERVCE ® 1.0% MIN
I CONNECT TO STORM STUB ® lE 323.8
I I I CB 1
Y { W VC 7EE
1 f f RIM 326.50
4" PVC SEWER SERVICE ® 20% MIN I III j 4" IE 325.00' (IN-S)
CONNECT TO SEWER STUB ® lE 324.0 I� t 6"fE 323.90 (OUT- W)
(SEE COE DETAIL SD-636
ON SHEET CN-01)
y� 1-1 2" WATER SERVICE LINE
DRIVEWAY = 950 sf
---� I UfNFIL
N884T19"W .\4 � CONNECT TO SERVICE LINE
42.40' I INSTALLED AS PART OF
SHORT PLAT
(TRACER WIRE TO BE
TRATION TRENCH TO BE INSTALLED WITH WATER LINE)
STRUCTED AS PART OF N0172'41
THE WALNUT SHORT PLAT ; :Fr..!- 4 10.50'
(PLN20200033)N8847"19"W
1111 s ------
DRY U7/Ll77ES III : I .. „ ' - M/N `�SDCO ' `-
I lE
CQ � Imo' 10' MIN LENGTH FOOTING
4" PVC_SSCO ttv DRAIN DRYWELL TRENCH
OF DRAIN o^ -` - - IE (PER GEOT£CH
I ® 1.09 MIN o 326.0E
G AG o RECOMMENDATIONS)
FT; 728.3 Z 5• 2
ROOF = 2,474
sf IN8147*19"W
PROPOSED HOUSE 4240'
MAIN FF 329.20
'A
I i 5 - B"BL 5'
� I 1
1 .COVERED W
I Q PA770 1
4" PVC FOOTING d
DRAIN ® 1.09 MIN r
a
N88 36 46 "W 102.40'
� ALL BUILDING SETBACK LINES
ON FLAG LOT TO BE 5FT TYP
5/25/2021
RAM Engineering 1653113" Ave W, Suite A108 Lynnwood WA 98037 (425)678-6960 RAMengineeringinc.com