APPROVED STM BLD2020-1146+Storm_Drainage_Report+10.25.2020_11.30.14_AMRAM Engineering BLD2020-1146
To: City of Edmonds
Engineering Division
From: Rob Long, PE
RAM Engineering
Subject: Purser Short Plat- Lot 1
Stormwater Memo
RAM Job No. 19-014
Memorandum
Date: October 14, 2020
COMPLIES WITH APPLICABLE
CITY STORMWATER CODE
RECEIVED
Oct 29 2020
CITY OF EDMONDS
DEVELOPMENT SERVICES
DEPARTMENT
This memo provides a summary of the stormwater hard surface allocation for Lot 1 of the Purser Short Plat
(PLN 20190040). A site -specific geotechnical evaluation recommends two stormwater BMPs for the site;
Infiltration and BMP T5.13: Post -Construction Soil Quality and Depth. Project impervious/hard surface (roof,
driveway, walk/patio areas) will be managed by a shared stormwater infiltration trench system with the short
plat development.
The infiltration trench system has been designed as part of the short plat development and thus includes hard
surface areas allocated for each individual lot (see Purser Short Plat Stormwater Site Plan Report). Lot 1 has
an allocation of 4,400 sf of impervious/hard surface, which include roof, driveway, patio, walkway and shared
driveway areas.
Below is a stormwater control summary table for Lot 1:
Stormwater Control Summary:
Project Site Category: Category 2 (part of the Purser Short Plat)
Discharge Location: City's Municipal Separate Storm Sewer System (MS4)
Type of Area
Square Footage
Stormwater Facility
Lawn and Landscape
4,016 sf
Soil Amendments (BMP T5.13)
Roofs
2,234 sf
1,960 sf
0 SF
Detention Vault
Hard Surfaces
Detention Vault
25% Retrofit
None
Purser Short Plot- Lot 1 Page 2 of 2
Stormwater Memo
RAM lob No. 19-014
Purser Short Lot 1 Hard Surface Summary:
Roof = 2,234 sf
Driveway = 610 s
Sidewalk/Patio = 200 sf 1,960 SF Total
Shared Drivewav = 1.150 sf
Total = 4,194 sf
I
Q` - SHORCONST PLAT MAR PA 142� AAAOAFDMDNDS� I
1NE PURSER SNORT PLAT WA 98020
J. �._� (PLN2079004Q1 PARCEL NO.
0039000W01200
CONNECT T,9
STORM S7U8 +
7E 276.5E I !
=
% GONNOCIFA TO .. P
SEWER SruB. ' ®° OX IDRIVEWAY 610 Si
N SHARED DRIVEWAY = 1,150 sf
I£v�aof I +
SEWER S Ns i• _! l5'ACCM AND
CEO - N• "FOR
93 FOR THE B£NEF7Y
MIN OF L075 7 R 2.
. R-168.73'
PATIOIWALK = 200 sl
• . �- � �� pR7y�.: / / N322553'E
Ill
CONC
PA770 COVERED ��@' /...- -�cu '� r i '� �� -•:
PLL4CN GARAGE ! N652128'W,�•
+F III } FF 2820 74.00' Ii ti l
ROOF = 2,234 sf /--------- i
UTRITY
PROPOSED HOUSE '� / 5'JOYNT EASEMENT
...� 4" P MAIN FF 28F.xWFQOPNG
. SS DRAW 00ISRED �' DRY U787RES i 3� `
PO' MMV LEM077t f,,OTwo
DRAW DRYWELL TRENCH
reEin►rMEtinAncw l I&
;t
�a t II
7,
----------
go ,A
\� EGISTE��/
IONeT ,
1011412020
RAM Engineering 165311311 Ave W, Suite A108 Lynnwood WA 98037 (425)678-6960 RAMengineeringinc.com