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365 10th St RES20-0139 Storm Water Restrictive CovenantComp. By: Date:5/13/2020 Public Works Department City of Atlantic Beach Permit No:_____________________________ Address:365 10th Street Atlantic Beach 32233 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) = 2,892 ft2 =38.6% V = 0.92 x 2,892.0 x 9.3 /12 V = 2,062 ft3 Provided Storage: Area 1 - Relative Elev.Area Storage Sideslope:2 :1 (ft)(ft2) (ft 3) 0.0 1,183 BOTTOM size:43 X 27.5 0.75 1,403 TOB size:46 X 30.5 Area 2 - Relative Elev.Area Storage (ft)(ft2) (ft 3) 0.0 0 BOTTOM size:0 X 0 0.00 0 TOB size:0 X 0 Area 3 - Relative Elev.Area Storage (ft)(ft2) (ft 3) 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) =1403.0 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 =1122.4 ft3 Required Treatment Volume =2,062 ft3 Supplied Treatment Volume =2,092 ft3 SW 970 0 0 Retention Stormwater Runoff for 10th 369 5/13/2020 2'-0"2' - 0 " 46' X 30.5' X 9"d ONSITE WATER RETENTION : With Turf Block 214 SQ FT 2,892 SQ FT 2,892 38.6% 2'-0" 30 ' - 6 " 46'-0" Grade site to drain to street per arrows (4 0 4 x 5 0 % ) 20 2 2, 6 6 6 35 . 5 % OV E R FL O W PO P - U P 6" H A R D A D S PI P E T O P O P U P AT S T R E E T 3 5 ' - 0 " 44 ' - 0 " 37 ' - 6 " 2 9 ' - 0 " Co m p . B y : Da t e : 6/ 2 / 2 0 2 1 Pu b l i c W o r k s D e p a r t m e n t Ci t y o f A t l a n t i c B e a c h Pe r m i t N o : RE S 2 0 - 0 1 3 9 Ad d r e s s : 36 5 1 0 t h S t r e e t ( F i n a l ) A d a m G r a y Re q u i r e d S t o r a g e V o l u m e Cr i t e r i a : Se c t i o n 2 4 - 6 6 o f t h e C i t y o f A t l a n t i c B e a c h ' s Z o n i n g, S u b d i v s i o n , a n d L a n d D e v e l o p m e n t R e g u l a t i o n s r e q ui r e s th a t s t o r m w a t e r r u n o f f f r o m i m p e r v i o u s a r e a s b e s t o re d o n s i t e . V o l u m e t o b e r e t a i n e d i s a s f o l l o w s : V = C A R / 1 2 wh i c h i s t h e M o d i f i e d R a t i o n a l M e t h o d f o r e s t i m a t i n g s t o r m w a t e r r u n o f f W h e r e : V = V o l u m e o f R u n o f f t o b e s t o r e d ( c u b i c f e e t ) C = R u n o f f C o e f f i c i e n t , 0 . 9 2 , t h e d i f f e r e n c e b e t w e e n i m p e r v i o u s a r e a ( C = 1 . 0 ) a n d u n d e v e l o p e d c o n d i t i o n s ( C = 0 . 0 8 ) . A = I m p e r v i o u s A r e a ( s q u a r e f e e t ) R= 2 5 - y r / 2 4 - h r r a i n f a l l d e p t h ( 9 . 3 i n c h e s f o r A t l an t i c B e a c h ) On s i t e S t o r a g e V o l u m e R e q u i r e d f o r I m p e r v i o u s A r e a : Lo t A r e a = 7, 5 0 0 ft 2 Im p e r v i o u s A r e a ( A ) = 2, 6 6 6 ft 2 = 35 . 5 % V = 0 . 9 2 x 2, 6 6 6 . 0 x 9 . 3 / 1 2 V = 1, 9 0 1 ft 3 Pr o v i d e d S t o r a g e : Ar e a 1 - R e l a t i v e E l e v . Ar e a St o r a g e Si d e s l o p e : :1 (f t ) ( f t 2 ) ( f t 3 ) 0. 0 1, 0 8 8 BO T T O M si z e : 37 . 5 X 29 0. 8 0 1, 5 4 0 TO B si z e : 44 X 35 Ar e a 2 - R e l a t i v e E l e v . Ar e a St o r a g e (f t ) ( f t 2 ) ( f t 3 ) 0. 0 0 BO T T O M si z e : 0 X 0 0 TO B si z e : X 0. 7 5 Ar e a St o r a g e (f t ) ( f t 2 ) ( f t 3 ) 0. 0 0 BO T T O M si z e : 0 X 0 0. 0 0 TO B si z e : 0 X 0 In g r o u n d S t o r a g e : = A * d / p f To t a l S t o r a g e A r e a a t T O B ( A ) = 15 4 0 . 0 ft 2 De p t h t o E S H W T f r o m B O T T O M ( d ) = 2. 0 ft , d e f a u l t i s 2 . 0 f t , v e r i f y o n s i t e E S H W T Po r e F a c t o r ( p f ) = 0 . 4 d e f a u l t i s 0 . 4 In g r o u n d S t o r a g e P r o v i d e d = 12 3 2 . 0 ft 3 Re q u i r e d T r e a t m e n t V o l u m e = 1, 9 0 1 ft 3 Su p p l i e d T r e a t m e n t V o l u m e = 2, 2 8 3 ft 3 1, 0 5 1 0 0 Re t e n t i o n S t o r m w a t e r R u n o f f f o r 1 0 t h S t r e e t - F i n al R e v . 6 / 2 / 2 0 2 1