APPROVED STM BLD2021-0645+Storm_Drainage_Report+5.10.2021_11.01.58_AM+2187449RAM Engineering ADDRESS:
To: City of Edmonds
Engineering Division
From: Rob Long, PE
RAM Engineering
Subject: Select Homes Walnu
Stormwater Memo
RAM Job No. 19-032
1000 WALNUT
COMPLIES WITH APPLICABLE
CITY STORMWATER CODE
BLD2021-0645
Memorandum
: May 7, 2021
RECEIVED
May 26 2021
CITY OF EDMONDS
DEVELOPMENT SERVICES
DEPARTMENT
This memo provides a summary of the stormwater hard surface allocation for Lot 4 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 4
has an allocation of 2,902 sf of impervious/hard surface, which include roof, driveway, patio and walkway
areas.
Below is a stormwater control summary table for Lot 4:
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
3,545 sf
Soil Amendments (BMP T5.13)
Roofs
2,502 sf
Infiltration Trench
Hard Surfaces
400 sf
Infiltration Trench
25% Retrofit
0 SF
None
Select Homes Walnut Short Plat- Lot 4
Stormwater Memo
RAM lob No. 19-032
Page 2 of 2
Walnut Short Lot 4 Hard Surface Summary:
Roof = 2,502 sf
Driveway = 400 sf
Sidewalk/Patio = 0 sf
Total = 2,902 sf
�I
a I I
z �
MILLER CRRISREN S/ I
o KLIAMS TAMMY L
1002 WALNUT Sr
EDMONDS� WA 98020
8 36,46,W
5 90'
INFILTRATION TRENCH TO DE
CONSTRUCTED AS PART CF
IHE WALNUT SNORT PLAT
(PLN20200033)
ca T
WIPvC TEE
RIM 3250
4" IE J22.fi0 IN-5)
4"IE 322.8D IN-E)
6"IE 322.60 (OUT -NW}
SET aN 6'S0 STUB
(SEE CX DETAIL SO-636
La7EcaRrON SHEET LN--DI)
f3uMPus .r
MI #OAR ST 10' MIN LENGTH F00110
EDMONDSI WA 98020 DRAIN DRYWELL TRENC
PARCEL AQ (PER CEOT=CM
270325Z,00700 RECCMMENDA TONS)
IPARCEL N0. I
004.y42=WID2 I
I I
r O Z
'o >
L1CflNECT TD SERVICE
INSTALLED ASPARTOT
SYHORT PLAT
7.,
(TRACER WIRE TO DE
NSTAtLED WTI WATER
O
41 yR F SE PVC' 1.0 B
C 44 SERVILE ®1.0% MIew
N i ,�I y -
4 �sco-
8,447 5F IE J225f
PROPOSED HOUSE,"j
MAIN FF 325.70
4" PVC SEWER SERVICE
® 2.09. MiNCONNECT TOCONCRETE:
SENERST-AI-FF
➢f�1YEWAr,, ; .
5/7/ZOZ1
BLOCK 35, CITY OF EDMOA
VOL. 2OFILATS, PG. 3!
I
5 1 6
GROOMS ,x VN A,
MCCOY FMILY S
10T8 WALNUT 51
I E➢M0/1L1S, WA 960.
PARCEL Na
004342035005OC
lBLN2G2a➢➢33)
WACT 999 Ir ACCY55/ UTLIT)'
RAM Engineering 1653113t1iAve W,Suite A108 Lynnwood WA 98037 (425)678-6960 RAMengineeringinc.com