Page 57 - planning-committee-packet

Drainage Area P-2 SGW#2

Total Area 40,379 sf Target ESDv = (P E )(Rv)(A)
Impervious Area 21,557 sf 12
Percent Impervious (I) 53 % = 3,213 cf
Rv = 0.05 +0.009(I) 0.53 75% of target= 2,410 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) = 4,998 cf
12
The computed ESDv provided is:

ESDv = (Ponding storage) + (Storage in media)
= 5,351 cf
Ponding ESDv = 2,554.7 cf
Surface Area= 2,618 sf Media Depth= 2.67 ft
Ponding Area= 3,059 sf
Ponding depth= 0.9 ft Porosity= 0.4
Therefore, when assessing compliance with the MEP standard, the volume of runoff treated by this submerged
gravel wetland is 4,998 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. 53 of 78