15xx Richardson - RES21-0187 Retention Calculations - 2nd Version 3-16-22Comp. By:
Date:3/4/2022
Public Works Department
City of Atlantic Beach
Permit No:
Address:1505 Richardson Lane
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 = 6,081 ft2
Impervious Area (A) = 2,373
ft2
=39.0%
V = 0.92 x 2,372.8 x 9.3 /
V = 1,692 ft3 Required
Provided Storage:
Area 1 - Relative Elev.Area Storage Sideslope:2 :1
(ft)(ft2)(ft3)
0.0 158 BOTTOM size:0 X
1.0 397 TOB size:0 X
Area 2 - Relative Elev.Area Storage
(ft)(ft2)(ft3)
0.0 10 BOTTOM size:-4 X
SCS
277
31
By Toni Gindlesperger at 2:10 pm, Mar 16, 2022
1.0 52 TOB size:0 X
Area 3 - Relative Elev.Area Storage
(ft)(ft2)(ft3)
0.0 66 BOTTOM size:-4 X
1.0 165 TOB size:0 X
Area 4 - Relative Elev.Area Storage
(ft)(ft2)(ft3)
0.0 25 BOTTOM size:-4 X
1.0 81 TOB size:0 X
Inground Storage:= A*d/pf
Total Storage Area at TOB (A) =695.1 ft2
Depth to ESHWT from BOTTOM (d) =2.0 ft, default is 2.0 ft, verify onsite ESHWT
Pore Factor (pf) =0.4 default is 0.4
Inground Storage Provided =556.1 ft3
Required Treatment Volume =1,692 ft3
Supplied Treatment Volume =1,033 ft3
31
115
53
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:
C = Runoff Coefficient, 0.92, the difference between impervious area (C=1.0)
12
0
0
-4
0
-4
0
-4
0