Page 56 - planning-committee-packet

Drainage Area P-1 SGW #1

Total Area 39,592 sf Target ESDv = (P E )(Rv)(A)
Impervious Area 21,882 sf 12
Percent Impervious (I) 55 % = 3,251 cf
Rv = 0.05 +0.009(I) 0.55 75% of target= 2,438 cf

Site Development Design - Submerged Gravel Wetland (M-2)
Based on the Cpv storm (2.8 in.): Max allowable ESDv that can be used:

V = (P)(Rv)(A) = 5,057 cf
12

The computed ESDv provided is:

ESDv = (Ponding storage) + (Storage in media)
= 11,342 cf
Ponding ESDv = 4,795.88 cf
Surface Area= 6,129 sf Media Depth= 2.67 ft
Ponding Area= 6,660 sf
Ponding depth= 0.75 ft Porosity= 0.4

Therefore, when assessing compliance with the MEP standard, the volume of runoff treated by this submerged
gravel wetland is 5,057 cf.

Now check for compliance with design criteria:
Submerged Gravel Wetland Design Criteria: Provided
_ Runoff shall enter, flowthrough, and exit in safe and non-erosive manner 
_ Drainage area to practice is large to maintain submerged flow 
Appropriate soils and/or high groundwater is present 
Section dimensions of soil media layers greater than minimum 
Distribution and collection piping / underdrains provided 
Flow paths through gravel greater than 15 ft 
Riser pipes provided and spaced at 15 ft or less apart 
Cleanouts provided 

8.13.25 PC Meeting Packet_pg. 52 of 78