1025 East Coast Drive RES24-0032 Calcs REVISION 3-25-24Comp. By:
Date:
Public Works Department
City of Atlantic Beach
Permit No:
Address:1025 East Coast Drive
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 = 7,500 ft2
Impervious Area (A) = 2,966 ft2 =39.5%
V = 0.92 x 2,966.0 x9.3/ 12
V = 2,115 ft3
Provided Storage:
Area 1 - REAR Area Storage Sideslope:4 :1
(ft)(ft2) (ft
3)
11.50 351 BOTTOM
12.0 1,081 TOB
Area 2 - Area Storage
(ft) (ft
2) (ft
3)
BOTTOM
TOB
Area 3 - Area Storage
(ft) (ft
2) (ft
3)
0 BOTTOM
0 TOB
Inground Storage: = A*d/pf
Total Storage Area at TOB (A) =1081.0 ft2
Depth to ESHWT from BOTTOM (d) =4.5 ft, default is 2.0 ft, verify onsite ESHWT
Pore Factor (pf) = 0.4 default is 0.4
Inground Storage Provided =1945.8 ft3
Required Treatment Volume =2,115 ft3
Supplied Treatment Volume =2,304 ft3
Reynold Peterson, P.E.
358
0
0
3/25/2023
Retention _atlantic beach _rev 1025 E Coast Drive 3/25/2024