45 Simmons Road_Calcs_16AUG21.xlsxComp. By:
Date:
Public Works Department
City of Atlantic Beach
Permit No:
Address:45 Simmons Road
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 = 6,860 ft2
Impervious Area (A) = 3,196 ft2 =46.6%
V = 0.92 x 3,196.0 x 9.3 / 12
V = 2,279 ft3
Provided Storage:
Area 1 - BACK Area Storage Sideslope:2 :1
(ft)(ft2) (ft
3)
9.3 717 BOTTOM size:X
11.8 717 TOB size:X
Area 2 - Area Storage
(ft)(ft2) (ft
3)
BOTTOM size:X
TOB size:X
Area 3 - Relative Elev.Area Storage
(ft)(ft2) (ft3)
0.0 0 BOTTOM size:0 X 0
0.0 0 TOB size:0 X 0
Inground Storage: = A*d/pf
Total Storage Area at TOB (A) =717.0 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 =573.6 ft3
Required Treatment Volume =2,279 ft3
Supplied Treatment Volume =2,366 ft3
1,793
0
0
10/4/2021
Retention 45 Simmons Road_Calcs_16AUG21 1/12/2022
By Toni Gindlesperger at 10:50 am, Jan 21, 2022