20170694 Ver 1_Wet Pond Desing_20170605

Wet Detention Pond Area and Volume
Drainage Area, (DA) =
23.19 ac
R/W Impervious Area (c=0.95) =
3.84 ac
Lot Impervious Area (c=0.95) =
7.76 ac (Assumes 3800 SF/Lot)
Amenity Impervious Area (c=0.95) =
0.00 ac
Lawn Area (c=0.35) =
11.59 ac
Woodland Area (c=0.25) =
0.00 ac
Cc =
0.65
Permanent Pool Elev = 335.5
332.0
Bottom Elevation = 329.0 (not inlcuded in pond
volume for sediment storage)
Average Depth Calculation:
Elevation
(ft)
Main
Area (sf)
Depth
(ft)
Main Inc.
Vol (cf)
I o a
Vol (cf)
330.0
12468
0
0
0
331.0
13687
1
13078
13078
332.0
14984
2
14336
27413
333.0
16368
3
15676
43089
334.0
17802
4
17085
60174
335.0
19267
5
18535
78709
335.5
22345
5.5
10403
89112
Average Depth =
Permanent Water Quality Pool
% Impervious =
Use Permanent Pool Depth =
SA / DA Ratio =
Required Surface Area =
Volume Provided =
Forebay Volume Provided =
Temporary Water Quality Pool
Design Storm Rainfall
Runoff Coeff. (Rv = 0.05 + 0.009 (% Imperv.)) _
Required Volume (design rainfall)(Rv)(DA) =
90% TSS Mountain and Piedmont Region
4.75 ft
50 %
5.00 ft
2.00 (from Tbl. 10-4)
20,214 sf
89,112 cf
17,822 cf
20 % of Main Vol
1.00 in
0.05 in/in
4,588 cf
SA / DA Ratios
Permanent Pool Depth
% Impervious
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
10
0.90
0.80
0.80
0.70
0.60
0.60
0.50
0.50
0.50
20
1.50
1.30
1.10
1.00
1.00
0.90
0.90
0.90
0.80
30
1.90
1.80
1.70
1.50
1.40
1.40
1.30
1.10
1.00
40
2.50
2.30
2.00
1.90
1.80
1.70
1.60
1.60
1.50
50
3.00
2.80
2.50
2.30
2.00
1.90
1.90
1.80
1.70
60
3.50
3.20
2.80
2.70
2.50
2.40
2.20
2.10
1.90
70
4.00
3.70
3.30
3.10
2.80
2.70
2.50
2.40
2.20
80
4.50
4.10
3.80
3.50
3.30
3.00
2.80
2.70
2.60
90
1 5.00
4.50
4.00
3.80
3.50
3.30
3.00
2.90
2.80

Wet Detention Pond Area and Volume
Drainage Area, (DA) =
24.09 ac
R/W Impervious Area (c=0.95) =
3.97 ac
Lot Impervious Area (c=0.95) =
8.90 ac (Assumes 3800 SF/Lot)
Amenity Impervious Area (c=0.95) =
0.00 ac
Lawn Area (c=0.35) =
11.22 ac
Woodland Area (c=0.25) =
0.00 ac
Cc =
0.67
Permanent Pool Elev = 335.5
293.0
Bottom Elevation = 329.0 (not inlcuded in pond
volume for sediment storage)
Average Depth Calculation:
Elevation
(ft)
Main
Area (sf)
Depth
(ft)
Main Inc.
Vol (cf)
I o a
Vol (cf)
291.0
18595
0
0
0
292.0
20168
1
19382
19382
293.0
21778
2
20973
40355
294.0
23425
3
22602
62956
295.0
25109
4
24267
87223
296.0
26830
5
25970
113193
296.5
30409
5.5
14310
127502
Average Depth =
Permanent Water Quality Pool
% Impervious =
Use Permanent Pool Depth =
SA / DA Ratio =
Required Surface Area =
Volume Provided =
Forebay Volume Provided =
Temporary Water Quality Pool
Design Storm Rainfall
Runoff Coeff. (Rv = 0.05 + 0.009 (% Imperv.)) _
Required Volume (design rainfall)(Rv)(DA) =
90% TSS Mountain and Piedmont Region
4.90 ft
53 %
5.00 ft
2.17 (from Tbl. 10-4)
22,784 sf
127,502 cf
25,500 cf
20 % of Main Vol
1.00 in
0.05 in/in
4,793 cf
SA / DA Ratios
Permanent Pool Depth
% Impervious
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
10
0.90
0.80
0.80
0.70
0.60
0.60
0.50
0.50
0.50
20
1.50
1.30
1.10
1.00
1.00
0.90
0.90
0.90
0.80
30
1.90
1.80
1.70
1.50
1.40
1.40
1.30
1.10
1.00
40
2.50
2.30
2.00
1.90
1.80
1.70
1.60
1.60
1.50
50
3.00
2.80
2.50
2.30
2.00
1.90
1.90
1.80
1.70
60
3.50
3.20
2.80
2.70
2.50
2.40
2.20
2.10
1.90
70
4.00
3.70
3.30
3.10
2.80
2.70
2.50
2.40
2.20
80
4.50
4.10
3.80
3.50
3.30
3.00
2.80
2.70
2.60
90
1 5.00
4.50
4.00
3.80
3.50
3.30
3.00
2.90
2.80

Wet Detention Pond Area and Volume
Drainage Area, (DA) =
16.14 ac
R/W Impervious Area (c=0.95) =
2.67 ac
Lot Impervious Area (c=0.95) =
5.84 ac (Assumes 3800 SF/Lot)
Amenity Impervious Area (c=0.95) =
0.00 ac
Lawn Area (c=0.35) =
7.63 ac
Woodland Area (c=0.25) =
0.00 ac
Cc =
0.67
Permanent Pool Elev = 335.5
324.0
Bottom Elevation = 329.0 (not inlcuded in pond volume for sediment storage)
Average Depth Calculation:
Elevation
(ft)
Main
Area (sf)
Depth
(ft)
Main Inc.
Vol (cf)
I o a
Vol (cf)
322.0
11218
0
0
0
323.0
12227
1
11723
11723
324.0
13275
2
12751
24474
325.0
14362
3
13819
38292
326.0
15488
4
14925
53217
326.5
18491
4.5
8495
61712
0.60
0.50
0.50
0.50
20
Average Depth =
Permanent Water Quality Pool
% Impervious =
Use Permanent Pool Depth =
SA / DA Ratio =
Required Surface Area =
Volume Provided =
Forebay Volume Provided =
Temporary Water Quality Pool
Design Storm Rainfall
Runoff Coeff. (Rv = 0.05 + 0.009 (% Imperv.)) _
Required Volume (design rainfall)(Rv)(DA) =
90% TSS Mountain and Piedmont Region
4.07 ft
53 %
4.00 ft
2.58 (from Tbl. 10-4)
18,151 sf
61,712 cf
12,342 cf
20 % of Main Vol
1.00 in
0.05 in/in
2,929 cf
SA / DA Ratios
Permanent Pool Depth
% Impervious
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
10
0.90
0.80
0.80
0.70
0.60
0.60
0.50
0.50
0.50
20
1.50
1.30
1.10
1.00
1.00
0.90
0.90
0.90
0.80
30
1.90
1.80
1.70
1.50
1.40
1.40
1.30
1.10
1.00
40
2.50
2.30
2.00
1.90
1.80
1.70
1.60
1.60
1.50
50
3.00
2.80
2.50
2.30
2.00
1.90
1.90
1.80
1.70
60
3.50
3.20
2.80
2.70
2.50
2.40
2.20
2.10
1.90
70
4.00
3.70
3.30
3.10
2.80
2.70
2.50
2.40
2.20
80
4.50
4.10
3.80
3.50
3.30
3.00
2.80
2.70
2.60
90
1 5.00
4.50
4.00
3.80
3.50
3.30
3.00
2.90
2.80

Wet Detention Pond Area and Volume
Drainage Area, (DA) =
31.71 ac
R/W Impervious Area (c=0.95) =
5.53 ac
Lot Impervious Area (c=0.95) =
10.99 ac (Assumes 3800 SF/Lot)
Amenity Impervious Area (c=0.95) =
0.00 ac
Lawn Area (c=0.35) =
15.19 ac
Woodland Area (c=0.25) =
0.00 ac
Cc =
0.66
Permanent Pool Elev = 286.5
283.0
Bottom Elevation = 280.0 (not inlcuded in pond
volume for sediment storage)
Average Depth Calculation:
Elevation
(ft)
Main
Area (sf)
Depth
(ft)
Main Inc.
Vol (cf)
I o a
Vol (cf)
281.0
26393
0
0
0
282.0
28000
1
27197
27197
283.0
29646
2
28823
56020
284.0
31329
3
30488
86507
285.0
33051
4
32190
118697
286.0
34810
5
33931
152628
286.5
38462
5.5
18318
170946
Average Depth =
Permanent Water Quality Pool
% Impervious =
Use Permanent Pool Depth =
SA / DA Ratio =
Required Surface Area =
Volume Provided =
Forebay Volume Provided =
Temporary Water Quality Pool
Design Storm Rainfall
Runoff Coeff. (Rv = 0.05 + 0.009 (% Imperv.)) _
Required Volume (design rainfall)(Rv)(DA) =
90% TSS Mountain and Piedmont Region
5.11 ft
52 %
5.00 ft
2.10 (from Tbl. 10-4)
29,074 sf
170,946 cf
34,189 cf
20 % of Main Vol
1.00 in
0.05 in/in
5,755 cf
SA / DA Ratios
Permanent Pool Depth
% Impervious
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
10
0.90
0.80
0.80
0.70
0.60
0.60
0.50
0.50
0.50
20
1.50
1.30
1.10
1.00
1.00
0.90
0.90
0.90
0.80
30
1.90
1.80
1.70
1.50
1.40
1.40
1.30
1.10
1.00
40
2.50
2.30
2.00
1.90
1.80
1.70
1.60
1.60
1.50
50
3.00
2.80
2.50
2.30
2.00
1.90
1.90
1.80
1.70
60
3.50
3.20
2.80
2.70
2.50
2.40
2.20
2.10
1.90
70
4.00
3.70
3.30
3.10
2.80
2.70
2.50
2.40
2.20
80
4.50
4.10
3.80
3.50
3.30
3.00
2.80
2.70
2.60
90
1 5.00
4.50
4.00
3.80
3.50
3.30
3.00
2.90
2.80

Wet Detention Pond Area and Volume
Drainage Area, (DA) =
31.42 ac
R/W Impervious Area (c=0.95) =
4.29 ac
Lot Impervious Area (c=0.95) =
7.24 ac (Assumes 3800 SF/Lot)
Amenity Impervious Area (c=0.95) =
1.80 ac
Lawn Area (c=0.35) =
18.09 ac
Woodland Area (c=0.25) =
0.00 ac
Cc =
0.60
Permanent Pool Elev = 299.5
296.0
Bottom Elevation = 293.0 (not inlcuded in pond
volume for sediment storage)
Average Depth Calculation:
Elevation
(ft)
Main
Area (sf)
Depth
(ft)
Main Inc.
Vol (cf)
I o a
Vol (cf)
294.0
13389
0
0
0
295.0
15206
1
14298
14298
296.0
17188
2
16197
30495
297.0
19336
3
18262
48757
298.0
21650
4
20493
69250
299.0
24121
5
22886
92135
299.5
29018
5.5
13285
105420
Average Depth =
Permanent Water Quality Pool
% Impervious =
Use Permanent Pool Depth =
SA / DA Ratio =
Required Surface Area =
Volume Provided =
Forebay Volume Provided =
Temporary Water Quality Pool
Design Storm Rainfall
Runoff Coeff. (Rv = 0.05 + 0.009 (% Imperv.)) _
Required Volume (design rainfall)(Rv)(DA) =
90% TSS Mountain and Piedmont Region
4.48 ft
42 %
4.50 ft
2.00 (from Tbl. 10-4)
27,332 sf
105,420 cf
21,084 cf
20 % of Main Vol
1.00 in
0.05 in/in
6,138 cf
SA / DA Ratios
Permanent Pool Depth
% Impervious
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
10
0.90
0.80
0.80
0.70
0.60
0.60
0.50
0.50
0.50
20
1.50
1.30
1.10
1.00
1.00
0.90
0.90
0.90
0.80
30
1.90
1.80
1.70
1.50
1.40
1.40
1.30
1.10
1.00
40
2.50
2.30
2.00
1.90
1.80
1.70
1.60
1.60
1.50
50
3.00
2.80
2.50
2.30
2.00
1.90
1.90
1.80
1.70
60
3.50
3.20
2.80
2.70
2.50
2.40
2.20
2.10
1.90
70
4.00
3.70
3.30
3.10
2.80
2.70
2.50
2.40
2.20
80
4.50
4.10
3.80
3.50
3.30
3.00
2.80
2.70
2.60
90
1 5.00
4.50
4.00
3.80
3.50
3.30
3.00
2.90
2.80

Wet Detention Pond Area and Volume
Drainage Area, (DA) =
7.27 ac
R/W Impervious Area (c=0.95) =
1.20 ac
Lot Impervious Area (c=0.95) =
2.53 ac (Assumes 3800 SF/Lot)
Amenity Impervious Area (c=0.95) =
0.00 ac
Lawn Area (c=0.35) =
3.54 ac
Woodland Area (c=0.25) =
0.00 ac
Cc =
0.66
Permanent Pool Elev = 309.5
306.0
Bottom Elevation = 303.0 (not inlcuded in pond volume for sediment storage)
Average Depth Calculation:
Elevation
(ft)
Main
Area (sf)
Depth
(ft)
Main Inc.
Vol (cf)
Total
Vol (cf)
304.0
2964
0
0
0
305.0
3793
1
3379
3379
306.0
4710
2
4252
7630
307.0
5719
3
5215
12845
308.0
6822
4
6271
19115
309.0
8016
5
7419
26534
309.5
10521
5.5
4634
31168
Average Depth =
Permanent Water Quality Pool
% Impervious =
Use Permanent Pool Depth =
SA / DA Ratio =
Required Surface Area =
Volume Provided =
Forebay Volume Provided =
Temporary Water Quality Pool
Design Storm Rainfall
Runoff Coeff. (Rv = 0.05 + 0.009 (% Imperv.)) _
Required Volume (design rainfall)(Rv)(DA) =
90% TSS Mountain and Piedmont Region
3.97 ft
51 %
4.00 ft
2.07 (from Tbl. 10-4)
6,541 sf
31,168 cf
6,234 cf
20 % of Main Vol
1.00 in
0.05 in/in
1,441 cf
SA / DA Ratios
Permanent Pool Depth
% Impervious
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
10
0.90
0.80
0.80
0.70
0.60
0.60
0.50
0.50
0.50
20
1.50
1.30
1.10
1.00
1.00
0.90
0.90
0.90
0.80
30
1.90
1.80
1.70
1.50
1.40
1.40
1.30
1.10
1.00
40
2.50
2.30
2.00
1.90
1.80
1.70
1.60
1.60
1.50
50
3.00
2.80
2.50
2.30
2.00
1.90
1.90
1.80
1.70
60
3.50
3.20
2.80
2.70
2.50
2.40
2.20
2.10
1.90
70
4.00
3.70
3.30
3.10
2.80
2.70
2.50
2.40
2.20
80
4.50
4.10
3.80
3.50
3.30
3.00
2.80
2.70
2.60
90
1 5.00
4.50
4.00
3.80
3.50
3.30
3.00
2.90
2.80