831 Beach Ave RES23-0016 Drain Calcs revision 4-27-23Comp. By:
Date:
Public Works Department
City of Atlantic Beach
Permit No:
Address:831 Beach Ave
Required Storage Volume
Criteria:
Section 24-66 of the City of Atlantic Beach's Zoning, Subdivsion, and Land Development Regulations requires
that stormwater runoff from impervious areas be stored onsite. Volume to be retained is as follows:
V = CAR/12 which is the Modified Rational Method for estimating stormwater runoff
Where:V = Volume of Runoff to be stored (cubic feet)
C = Runoff Coefficient, 0.92, the difference between impervious area (C=1.0)
and undeveloped conditions (C=0.08).
A = Impervious Area (square feet)
R= 25-yr / 24-hr rainfall depth (9.3 inches for Atlantic Beach)
Onsite Storage Volume Required for Impervious Area:
Lot Area = 17,509 ft2
Impervious Area (A) = 8,857 ft2 =50.6%
V = 0.92 x 8,857.0 x 9.3 /12
V = 6,315 ft3
Provided Storage:
Area 1 Area Storage Sideslope:14 :1
(ft)(ft2) (ft
3)
BOTTOM
TOB
Area 2 -LEFT REAR Area Storage
(ft)(ft2) (ft
3)
13.00 416 BOTTOM
14.25 2,461 TOB
Area 3 - RIGHT REAR Area Storage
(ft)(ft2) (ft
3)
0 BOTTOM
0 TOB
Inground Storage: = A*d/pf
Total Storage Area at TOB (A) =2461.0 ft2
Depth to ESHWT from BOTTOM (d) =5.0 ft, default is 2.0 ft, verify onsite ESHWT
Pore Factor (pf) = 0.4 default is 0.4
Inground Storage Provided =4922.0 ft3
Required Treatment Volume =6,315 ft3
Supplied Treatment Volume =6,720 ft3
Reynold Peterson, P.E.
0
1,798
0
4/25/2023
Retention 831 Beach Ave_CALCS 4/25/2023