SW3230301_Calculations_20230919

Kerns Ridge vM I IJ1 CREED
PROJECT NO.: 08433-0001 = C
DATE: 09/19/22 T.M.: JCB
REVISED: 09/19/23 P.M.: JCB I WET POND#1 CALCULATIONS I DESIGN OBJECTIVE
Avret pond shall be designed to capture the design stoma and release it slowly over a period of two to five days via a properly designed outlet structure.The first outlet in the structure is
designed to be above the bottom of the pond,thus creating a permanent pool of water.Stomnvater shall have an adequate flowpath to bring about removal ofTSS through dilution and
settling.The pond shall be designed in a manner that protects the device,the areas around the device and the receiving stream from erosion.The pond also must be maintained properly to
prevent the resuspension of captured sediments.
SITE CHARACIERISTICS
Drainage Area 416,869 ft2
Post-development impervious area 171,150 ft2
Post-development impervious percentage 41%
Design rainfall depth 1.0 in
DESIGN VOLUME
Mnumun volume required 14,556 113 3630 x rainfall depth x drainage area x(0.05+0.9 x impervious percentage)
Volume provided 15,534 113 See Stage-Storage table below
ELEVATIONS
Temporary pool elevation 713.50 find
Permanent pool elevation 712.50 find
Top of 6ft vegetated shelf elevation 713.00 find
Bottom of61i vegetated she lfelevation 712.00 find
Sediment cleanout,top elevation(bottom of pond) 708.00 find
Sediment cleanout,bottom elevation 707.50 find
Sediment storage depth provided 0.5 ft
SURFACE AREAS
Temporary pool area 16,998 ft2 See Stage-Storage table below
Main pool area REQUIRED 7,462 ft2 SA/DAratio x Drainage Area
Nhin pool area PROVIDED 11,360 ft2 See Stage-Storage table below
SA/DAratio 1.79 From SA/DAtable for Piedmont/Nbuntains(50%impervious,3.0 feet average depth)
Bottom of vegetated shelf area 10,332 ft2 See Stage-Storage table below
Bottom of main pool area 5,412 ft2 See Stage-Storage table below
VOLUMES
Temporary pool volume 15,534 113 See Stage-Storage table below
Msin pool volume 34,339 113 See Stage-Storage table below
Forebay volume 5,370 113 See Stage-Storage table below
Forebay%of Min pool volume 15.64% OK

Kerns Ridge v M I I u1 CREED
PROJECT NO.: 08433-0001 = C
DATE: 09/19/22 T.M.: JCB
REVISED: 09/19/23 P.M.: JCB WET POND#1 CALCULATIONS
1 - MAIN POOL STAGE-STORAGE TABLE
Elevation Area(sfl Area Volume Volume
(msl) (ac) (cu-11) (ac-it)
708.00 4937 0.1133 0 0.0000
709.00 6084 0.1397 5495 0.1261
710.00 7297 0.1675 12170 0.2794
711.00 8570 0.1967 20087 0.4611
712.00 9537 0.2189 29127 0.6687
712.50 11360 0.2608 34339 0.7883
FOREBAY STAGE-STORAGE TABLE
Elevation Area(sfl Area Volume Volume
(msl) (ac) (cu-ff) (ac-it)
709.50 1305 0.0300 0 0.0000
710.00 1458 0.0335 690 0.0158
711.00 1783 0.0409 2306 0.0529
712.00 2133 0.0490 4259 0.0978
712.50 2317 0.0532 5370 0.1233
TENPORARYPOOLSTAGE-STORAGE TABLE
Elevation Area(sfl Area Volume Volume
(nisi) (ac) (cu-ff) (ac-it)
712.50 14189 0.3257 0 0.0000
713.00 15517 0.3562 7417 0.1703
713.50 16998 0.3902 15534 0.3566
S A/DA TABLE DATA
Coastal SA/DAtable used? N
Mbuntains/Piedmont SA/DAtable used? Y
SA/DAratio 1.79 From SA/DAtable for Piedmont/Mountains(50%impervious,3.0*et average depth)
Average depth 3.02 ft IVhln pool volume/Ain pool surface area
DRAWDOWN CALCULATIONS
Diawdown through orifice? Y
Diairrter of orifice(if circular) 2.00 in
Area of orifice 0.02 ft2
Coefficient of discharge(CD) 0.60 (witless)
Diving head(1-10) 0.33 it
Design volume drawdown time 2.96 days OK draws down in 2-5 days.