340 W 14TH ST ACC23-0031 Revision sheet Rev. 2-20-24ACC23-0031
Retention 340 14th St W 2/14/2024
Comp. By:
Date:
Required Storage Volume
NAME
2/14/2024
Public Works Department
City of Atlantic Beach
Permit No:
Address:
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:
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)
Swale w/ NO WALL SLOPE
X
X
X
X
X
X
X
X
X
X
X
X
2.5
_____________________________
340 14th St W
7,140
1,500
3
0.0
0.0 0 0
10.75
11.50 13 35
10.75
11.50 4 11
11.00
11.75 5.5 5
10.25
11.00 25 12
0.0
0.0 0 0
2.0
Criteria:
V = CAR/12
Onsite Storage Volume Required for Impervious Area:
Lot Area = ft2
Impervious Area (A) =
V = 0.92 x x 9.3 /12
V = ft3
Provided Storage: Swale 1
Swale 1 - Relative Elev.Area Storage Sideslope::1
(ft)(ft2)(ft3)
BOTTOM size:
TOB size:
FD 1 - Relative Elev.Area Storage
(ft)(ft2)(ft3)
BOTTOM size:
TOB size:
FD 2 - Relative Elev.Area Storage
(ft)(ft2)(ft3)
BOTTOM size:
TOB size:
FD 3 - Relative Elev.Area Storage
(ft)(ft2)(ft3)
BOTTOM size:
TOB size:
FD 4 - Relative Elev.Area Storage
(ft)(ft2)(ft3)
BOTTOM size:
TOB size:
FD 4 - Relative Elev.Area Storage
(ft)(ft2)(ft3)
BOTTOM size:
TOB size:
Inground Storage:= A*d/pf
Total Storage Area at TOB (A) =ft2
Depth to ESHWT from BOTTOM (d) =ft, default is 2.0 ft, verify onsite ESHWT
Pore Factor (pf) =0.4 default is 0.4
Inground Storage Provided =ft3
Required Treatment Volume =ft3
Supplied Treatment Volume =ft3
ft2 21.0%
1,500.0
1,070
0 0 0 10
0
259 268 8.5 30.5
455
-3 15 -0.5 6.5
44
1 11 1 0.5
28
154 170 20.5 7.5
300
0 0 0 0
0
826.5
661.2
1,070
1,125
LEGEND ENGINEERING
Commercial l Marine l Residential
800 Seminole Road
Atlantic Beach, FL 32233
Phone: 904-247-5800
Fax: 904-247-5805
Permit number: ACC23-0031
Project Address: 340 W 14th St, Atlantic Beach, FL
Comment response: Review 3
Zoning:
a. Please show the height of the detached garage as measured from grade to
the top of the roof. The maximum height is 15 feet, except it can be up to 25
feet tall if it is 10 feet from the rear( west) property line.
i. Detail provided on the geometry sheet - see sheet 3 of 5
ii. The proposed detached garage is 15 ft in height from the adjacent
grade
iii. Overall height is 14.5’
Public Works:
b. Water retention is not sufficient - see attached documentation.
i. Ponds have been deepened
ii. COAB does not accept an ESHWT of 2.5 below the pond bottom.
iii. Average pond depth is now 0.75 ft
iv. Required storage volume is 1,070 cu ft
v. Provided storage volume is 1,125 cu ft
Should you have any questions please don’t hesitate to contact me directly at (813)
389-0835.
Thanks,
Ricky Jackson, PE