SW3200903_Wet Pond-ETARC_20210416

Wet Pond NCDENR 2007 SHOPTON RIDGE BUSINESS PARK 4/16/2021
CHARLOTTE,NC
WATER QUALITYBASIN DESIGN _
Pond Volume Linked to Worksheet: Wet Pond Volume
85% Total Suspended Soilds
25% Total Nitrogen
40% total Phosphate
SURFACE AREA REQ'D
Drainage Area =ac
% Impervious =-%
Try Perm. Pool Depth =-
SA/DA= -
Surface Area Req'd = ac
Area Provided = 2.43 ac
at Elev = 830.50
VOL prov'd perm pool= 9.56 ac-ft
Avg Depth =�ft
Actual Ratio = 3.11
Actual Area Req'd = 1.408 ac
Design TSS% Removal Rate
85 %
- sf
sf
(includes Fore -bay)
Mountain & Piedmont Regions
T.hlu in-1
SAIDA RATIO CHART (for 85% TSS removal)
% imp cover avg.
permanent pool depth (ft)
3
4
5
6
7
8
9
10
0.51
0.49
0.43
0.35
0.31
0.29
0.26
20
0.84
0.79
0.70
0.59
0.51
0.46
0.44
30
1.17
1.08
0.97
0.83
0.70
0.64
0.62
40
1.51
1.43
1.25
1.05
0.90
0.82
0.77
50
1.79
1.73
1.50
1.30
1.09
1.00
0.92
60
12.0912.03
1.71
1.51
1.29
1.18
1.10
70
2.51
2.40
2.07
1.79
1.54
1.35
1.26
80
2.92
2.78
2.38
2.10
1.86
1.60
1.42
90
3.25
3.10
2.66
2.34
2.11
1.83
1.67
Perm. pool elevation should be Mountain & Piedmont Regions
within 6" +/- of the SHWT Table 10-3
(Seasonal High Water Table)
TEMP. DRAWDOWN
DETERMINE 1" STORM VOLUME
USE SIMPLE METHOD Rv=0.05+0.009(I)
Rv= = IN/IN
P= IN
VOLUME=DESIGN RAINFALL(Rv)DA
VOLUME= -AC -FT 141,293 CIF
VOLprov= AC -FT at elevation F 831.80
FORE -BAY SIZE
PRE -BAY VOL=20% OF PERM POOL VOLUME
Includes Forebay &
PRE -BAY VOLregd= F1.911 Jacac-ft Main Pond
PRE -BAY VOLprov.= 1.845-ft
Actual % Used = 19.3 %
Average depth should be a minimum
of 3 feet.
Average depth, day may be computed
by:
Option 1: d,, = Vol Perm. pool
Area perm. pool
Option 2: ( see NCDENR Manual )
$A/DA RATIO CHART (for 90% TSS removal)
% imp cover avg. permanent pool depth (ft)
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
10
0.9
0.8
0.8
0.7
0.6
0.6
0.5
0.5
0.5
0.5
0.4
0.4
0.4
20
1.5
1.3
1.1
1.0
1.0
0.9
0.9
0.9
0.8
0.8
0.8
0.7
0.7
30
1.9
1.8
1.7
1.5
1.4
1.4
1.3
1.1
1.0
1.0
1.0
0.9
0.9
40
2.5
2.3
2.0
1.9
1.8
1.7
1.6
1.6
1.5
1.4
1.3
1.2
1.1
50
3.0
2.8
2.5
2.3
2.0
1.9
1.9
1.8
1.7
1.6
1.6
1.5
1.5
60
1 3.5
1 3.2
2.8
1 2.7
2.5
1 2.4
2.2
2.1
1.9
1.9
1.81
1.8
1.7
70
4.0
3.7
3.3
3.1
2.8
2.7
2.5
2.4
2.2
2.1
2.0
2.0
1.9
80
4.5
1 4.1
3.8
3.5
3.3
1 3.0
2.8
2.7
2.6
2.4
2.3
2.1
2.0
90
5.0
1 4.5
4.0
3.81
3.51
3.31
3.0
1 2.9
2.81
2.7
2.6
2.5
2.4
ORIFICE SIZING ORIFICE CALCULATIONS
orifice formula Q=cA(2gh)A.5 w/ c=.6
2 DAY DRAWDOWN Q2= -cfs
DIA (in)
5 DAY DRAWDOWN= Q5= -cfs Inv=
(cfs)
FROM ORIFICE CALC'S: USE w IN DIA ORIFICE (2) Elev Q
' Top 1" Stor = 831.80 Driving Head = H/3
Approx Draw Down Time = 2.3 days Perm. Pool = 830.5
See Figure 3-3 NCDENR BMP
56 hours Head = LO.43 Manual
Avg Q = Enh, cfs
Note: Formula modifed for (2) 6" orifices
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BOUYANCY CALCULATIONS
Weight of Structure Type
Box
Inside Width
4.0
FT
Inside Length
4.0
Wall Thickness
0.5
Concrete CY/FT of Height
0.33
Structure Height
11.85
FT
Total Structure
3.95
Pipe Deduction
0.127
Total Vol. of Concrete
3.82
Concrete LB/CY
145
Weight of Structure (Wstructure)
8,340
ANCHOR DIM'S
L= 5.0
W=1 5.0
W etr-t— + W anchor
WmQ Treqd= 2.84 ft
34.03 in
Tprov'd= 36 in
Wt. Anchor Prov'd = 6195.00 Ibs
Total Wt. of Outlet = 14535.26 Ibs
SFpratded = 1.23
Pipe Deductions
per NCDOT 840.02
Dia.
CY
12
0.032
15
0.036
18
0.049
24
0.085
30
0.127
36
0.178
42
0.243
48
0.317
54
0.401
BouVanCV Calculations
BF=VOIRi—xDensityH2o 11,831.04 LBS
Wt. Conc.=145-62.4(LB/C LB/CF
SFreq=-
Total Wt. Required(Wreq)= LBS
VOL OF ANCH REQ'D= CF
(W req - W structure) / 82.6
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