HomeMy WebLinkAboutS-1904 Water Course Data 092021Drawn By:Date:Scale:AHR09-19-20211"=2000'REVISION DESCRIPTION DATENO
XX X-X-X
C-5015800 Evergreen DriveLittle Rock, AR 72205Ph (501)663-8800Fax (501)588-0123www.harborenv.comHarborO AND O SUBDIVISION
DENNY ROAD, PULASKI COUNTY, ARKANSAS
WATER COURSE DATA
O AND O PROPERTY HOLDINGS, LLC WATERSHED 11062.79 AC25-YR FLOW = 934 CFS100-YR FLOW = 1,330 CFSFLOW ENTERING PROPERTY VIA WILDWOOD CREEKSTREAMSTAT CALCULATIONWATERSHED 31.87 AC25-YR FLOW = 3.92 CFS100-YR FLOW = 4.76 CFSONSITE DRAINAGE TO WILDWOOD CREEKQ=CIAWATERSHED 223.61 AC25-YR FLOW = 62.3 CFS100-YR FLOW = 92.4 CFSFLOW ENTERING WILDWOOD CREEK FROM NORTHOF DENNY ROAD & ONSITE DRAINAGESTREAMSTAT CALCULATIONWATERSHED 47.94 AC25-YR FLOW = 16.67 CFS100-YR FLOW = 20.25 CFSONSITE DRAINAGE TO WEST PROPERTY LINEQ=CIAWATERSHED 51.07 AC25-YR FLOW = 2.25 CFS100-YR FLOW = 2.73 CFSONSITE DRAINAGE TO SOUTH PROPERTY LINEQ=CIAWATERSHED 67.38 AC25-YR FLOW = 15.49 CFS100-YR FLOW = 18.81 CFSONSITE DRAINAGE TOWILDWOOD CREEKQ=CIA1,035 CFS = FLOW LEAVING SITE, PRE-CONSTRUCTION, 25-YEAR STORM1,469 CFS = FLOW LEAVING SITE, PRE-CONSTRUCTION, 100-YEAR STORM
PRE‐CONSTRUCTION
WATERSHED AREA A I25 I100 CQ25, CFS Q100, CFS
1 46290801 sf 1062.69 ac 934 1330
2 6448.084 sf 0.15 ac 62.3 92.4
3 81394.59 sf 1.87 ac 7 8.5 0.3 3.92 4.76
4 345840 sf 7.94 ac 7 8.5 0.3 16.67 20.25
5 46631.86 sf 1.07 ac 7 8.5 0.3 2.25 2.73
6 321299.6 sf 7.38 ac 7 8.5 0.3 15.49 18.81
1015.71 1445.97
1034.63 1468.95
POST CONSTRUCTION, WEIGHTED C CALCULATIONS
3 81394.59 sf 1.87 ac 7 8.5 0.3 3.92 4.76
6000 sf 0.14 ac 7 8.5 1 0.96 1.17
87394.59 sf 2.01 ac 7 8.5 0.348 4.89 5.94
4 339840 sf 7.80 ac 7 8.5 0.3 16.38 19.89
6000 sf 0.14 ac 7 8.5 1 0.96 1.17
345840 sf 7.94 ac 7 8.5 0.312 17.35 21.07
6 321299.6 sf 7.38 ac 7 8.5 0.3 15.49 18.81
6000 sf 0.14 ac 7 8.5 1 0.96 1.17
327299.6 sf 7.51 ac 7 8.5 0.313 16.45 19.98
POST CONSTRUCTION
WATERSHED AREA A I25 I100 CQ25, CFS Q100, CFS
1 46290801 sf 1062.69 ac 934 1330
2 6448.084 sf 0.15 ac 62.3 92.4
3 81394.59 sf 1.87 ac 7 8.5 0.3 3.92 4.76
4 345840 sf 7.94 ac 7 8.5 0.31 17.23 20.92
5 46631.86 sf 1.07 ac 7 8.5 0.35 2.62 3.18
6 321299.6 sf 7.38 ac 7 8.5 0.31 16.01 19.44
TOTAL LEAVING VIA CREEK 1016.23 1446.60
TOTAL LEAVING PROPERTY 1036.08 1470.71
DIFFERENCE, PRE VS. POST 1.45 1.76
DESIGN OF DETENTION POND AND OUTLET STRUCTURE
SITE DEVELOPMENT
O AND O SUBDIVISION, DENNY RD, PULASKI COUNTY, ARKANSAS
FOR O AND O PROPERTY HOLDINGS, LLC
BY: HARBOR ENVIRONMENTAL, INC.
SEPTEMBER 19,2021
TOTAL LEAVING VIA CREEK
TOTAL LEAVING PROPERTY
Post‐Construction (Watershed 6):
Drainage Area (A) = 7.38 sf
Runoff Coef. (Cpost) = 0.31
Intensity (I25) = 7 in/hr
Intensity (I100) = 8.5 in/hr
Discharge Flow (Q25‐post) = 16.01 cfs
Discharge Flow (Q100‐post) = 19.44 cfs
Time of Conc. (tc‐post) = 32.6 min, (HydraCAD)
Allowable Outflow Peak (Watershed 6)
Discharge Flow (Q25‐pre) = 14.04 cfs
Storage Required
s = 1/2 x (Q25‐post ‐ Q25‐pre) x tb x 60
tb = 2.67 x tp
tp = D/2 + 0.6Tc‐post
D = 3.0 min
tp = 21.1 min
tb = 56.2 min
s = 3,312 cf
0.076 ac‐ft
Storage Provided
Storage = 15,497 cf
0.356 ac‐ft
Freeboard =1ft
Outlet Structure
Inlet Sizing:
D =8in
H = 2.1667 ft
Q =3.78D2H0.5
Q = 2.47 cfs per inlet
For Qin (Q25‐pre) = 14.04 cfs, use 6 x 8" culverts
Outlet Sizing:
D = 8in
H = 2.1667 ft
Q =3.78D2H0.5
Q = 2.47 cfs per inlet
For Qout (Q100‐post) = 19.44 cfs, use 8 x 8" culverts