831 Beach Ave RES23-0016 Drain Calcs REVISION 3-31-23Comp. 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) = 0 ft2 =0.0%SITE HAS NO NET INCREASE IN IMPERVIOUS AREA
V = 0.92 x 0.0 x 9.3 /12
V = 0 ft3
10" PIPE XSEC AREA = 0.55 FT2
Provided Storage:
Area 1 - Right 10" PIPE Area Storage Sideslope:4 :1
(ft)(ft2) (ft
3)
145.0 0.55 BOTTOM
TOB
Area 2 -LEFT 10" PIPE Area Storage
(ft)(ft2) (ft
3)
136.0 0.55 BOTTOM
TOB
Area 3 -Area Storage
(ft)(ft2) (ft
3)
0 BOTTOM
0 TOB
Inground Storage: = A*d/pf
Total Storage Area at TOB (A) =281.0 ft2
Depth to ESHWT from BOTTOM (d) =6.0 ft, default is 2.0 ft, verify onsite ESHWT
Pore Factor (pf) = 0.4 default is 0.4
Inground Storage Provided =674.4 ft3
Required Treatment Volume =0 ft3
Supplied Treatment Volume =829 ft3
Reynold Peterson, P.E.
80
75
0
3/8/2023
Retention 831 Beach Ave_CALCS 3/27/2023