360 8th St RES22-0143 Civil Engineering Calculations REVISION 3-22-23Comp. By:
Date:2/23/2023
Public Works Department
City of Atlantic Beach
Permit No:_____________________________
Address:360 8th street
Required Storage Volume
Criteria:
Section 24-68 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 = 6,500 ft2
Impervious Area (A) = 2,925 ft2 =45.0%
V = 0.92 x 2,925.0 x 9.3 /12
V = 2,086 ft3
Provided Storage:
Area 1 - Relative Elev.Area Storage Sideslope:2 :1 FRONT YARD
(ft)(ft2) (ft
3)
8.0 400 BOTTOM size:10 X 40
8.5 400 TOB size:10 X 40
Area 2 - Relative Elev.Area Storage
(ft)(ft2) (ft
3)
8.0 0 BOTTOM size:X
8.5 0 TOB size:X
Area 3 - Relative Elev.Area Storage side of pool and behine pool not under deck
(ft)(ft2) (ft
3)REAR YARD
8.0 765 BOTTOM size:34 X 22.5
9.0 765 TOB size:34 x 22.5
between pool and behind pool under deck
Inground Storage: = A*d/pf
Total Storage Area at TOB (A) =1165.0 ft2
Depth to ESHWT from BOTTOM (d) =2.5 ft, default is 2.0 ft, verify onsite ESHWT
Pore Factor (pf) = 0.4 default is 0.4
Inground Storage Provided =1165.0 ft3
Required Treatment Volume =2,086 ft3
Supplied Treatment Volume =2,130 ft3
200
0
765
Retention 360 8th street drainage22323 2/24/2023
By Toni Gindlesperger at 11:11 am, Mar 22, 2023