APPROVED_STM_BLD2021-0009+Storm_Drainage_Report+1.4.2021_2.59.37_PM+1972684RAM Engineering BLD2021-0009
LOT 3
1004 WALNUT Memorandum
To: City of Edmonds Date: December 31, 2020
Engineering Division RECEIVED
Apr 22 2021
From: Rob Long, PE CITY OFEDMONDS
DEVELOPMENT SERVICES
RAM Engineering DEPARTMENT
Subject: Select Homes Walnut Short Plat- Lot 3
Stormwater Memo
RAM Job No. 19-032
COMPLIES WITH APPLICABLE
CITY STORMWATER CODE
This memo provides a summary of the stormwater hard surface allocation for Lot 3 of the Purser 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 3
has an allocation of 3,542 sf of impervious/hard surface, which include roof, driveway, patio and walkway
areas.
Below is a stormwater control summary table for Lot 3:
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
Stormwater Facility
Lawn and Landscape
2,742 sf
Soil Amendments (BMP T5.13)
Roofs
2,417 sf
Infiltration Trench
Hard Surfaces
1,125 sf
Infiltration Trench
25% Retrofit
0 SF
None
Select Homes Walnut Short Plat- Lot 3 Page 2 of 2
Stormwater Memo
RAM lob No. 19-032
Walnut Short Lot 3 Hard Surface Summary:
Roof = 2,417 sf
Driveway = 1,075 sf
Sidewalk/Patio = 50 sf
Total = 3,542 sf
4
4" PVC SEWER SERVCE 0 2.0X MIN ti
N CONNECT TO WER STUB 0 IE 324.Ot t � � TRACT 999
ACCESS/
6" PVC STORM SERVICE 6 LOX MIN - ` � I � UTILITY
CONNECT TO STORM STUB 0 IE 324.6-E
INFIL7RA77ON TRENCH TO 6E SSCO +III I I CB 1
IF DRIVEWAY = 1,075 sf IN
CONSTRUCTED As PART of I j I 6 RIM 327. 7a
THE WALNUT SNORT PLAT N8847'19"W 64.90, 324.0f
(PLN20200033) _� -__{ 4" IE 325.00 (IN-S)
— J +
6" IE 324.00 (OUT-W)
'—F-
i . .. �.-{--_ --- —_
16' MIN LENGTH F00I7MG � a
DRAIN .PR.YINELL TRENCH �
-. (PER GEOTECH I 4" PVC -
RECOMMENDA770NS) ROOF DRAIN
WALK = 50 sf CONCRETE. I � 1.0X MIN
DRIVEWAY I _
CEDAR ST - _ _ _ -- 1-1 2" WA7FR SEROCE LINE--- - -------
A SSCO GARAGE B CONNECT TO SERVICE LINE
INSTALLED AS PART of
q" .. .. 0777VG o 327.0 329.0 L — SHORT PLAT'
_ RAIN ® 1.0% MIN Ln COVERED (TRACER WIRE TO BE
rn PORCH INSTALLED W rH WATER LINE)
— — — — Q 3 n DRY U77LI77ES
PROPOSED HOUSE- rn
">1 MAIN FF 330.50 { S000
�F ROOF = 2.417 sf 1a IE 326.4f
ry _
LLOYD GERALD L a r —
960 CEDAR ST Q Z
EDMONDS WA 98020 '
PARCEL NO. o a 5
27032500101200
Ir----------------- - -
N8836 46"W 65.20'
\NONTAI.
12/31/202-0
RAM Engineering 165311311 Ave W, Suite A108 Lynnwood WA 98037 (425)678-6960 RAMengineeringinc.com