20191431 Ver 1_BEAM ROAD WET POND CALCS_20191017

B U R T O N BEAM ROAD
E N G IN E ER ING
Sheet: WQ-Pond
WATER QUALITY POND DESIGN PROCEDURE
(Based on Chapter 4.2.8 Example from Charlotte -Mecklenburg BMP Design Manual)
Design Efficiency Pond Volume Linked to Worksheet: Pond Volume
TSS-Only
Table 4.2.1 Design Values and Pollution Removal Rates
Threshold
Min. WQv
Detention Time
Maximum WQv/PPv Ratio
Pollution Removal Rate
Optimal
4.0 Days
0.3
85% TSS 70% TP
Standard
2.0 Days
0.6
60% TSS 60% TP
TSS-Only
4.0 Days
0.4
85% TSS 0% TP
WATER QUALITY VOLUME
SURFACE AREA REQ D
Drainage Area to WQ Pond = 96.00 ac
Percent Imp. = 80.0 %
Curve Number= 91.7 (Std. CN)
COMPUTE WATER QUALITY PEAK FLOW (WQP)
Compute Runoff Coefficient, Equation 3.1
Rv= 0.770
Design Storm = 1.00 in
Compute Water Quality Vol, Equation 3.2
WQv = 6.1600 ac-ft
268,330 jcf
Convert Water Quality Vol to Inches, Equation 3.3
WQv = 0.77 Inches
Compute modified SCS curve number, Equation 3.4
CNModified = 97.8
PModified = 1.49 Inches
Release Rate = 1.461 cfs
( Approximate for Static Method

B U R T O N
R I N G
Sheet:Pond Volume
Elev Perm Pool =
Area of Perm. Pool =
Vol. Main Pond=
Vol.PreBay=
Vol.Perm Pool=
Temp. Pool Elev=
Temp. Pool Vol=
Temp. Pool Area=
Pond Volumes
637
1.730
16.410
0.000
16.410
639.75
-16.410
0.000
sf
ac-ft
ac-ft
ac-ft
ac-ft
ac
BEAM ROAD 10/16/2019
Pond Volume Linked to Worksheet:
WQ-Pond
Main Pond
PreBay
Total
Inc.
Total
Avg.
Inc.
Total
Total
Contour
Area
Avg. Area
Vol.
Vol.
Area
Area
Vol.
Vol.
Area
Cum. Vol.
Elev
(ac)
(ac
ac-ft
ac-ft
ac
ac
ac-ft
ac-ft
ac
ac-ft
625
1.030
0.000
0.000
0.000
0.000
0.000
0.000
0.000
1.030
0.000
626
1.080
1.055
1.055
1.055
0.000
0.000
0.000
0.000
1.080
1.055
628
1.190
1.135
2.270
3.325
0.000
0.000
0.000
0.000
1.190
3.325
630
1.310
1.250
2.500
5.825
0.000
0.000
0.000
0.000
1.310
5.825
632
1.420
1.365
2.730
8.555
0.000
0.000
0.000
0.000
1.420
8.555
634
1.540
1.480
2.960
11.515
0.000
0.000
0.000
0.000
1.540
11.515
636
1.660
1.600
3.200
14.715
0.000
0.000
0.000
0.000
1.660
14.715
637
1.730
1.695
1.695
16.410
0.000
0.000
0.000
0.000
1.730
16.410
637.5
1.880
1.805
0.903
17.313
0.000
0.000
0.000
0.000
1.880
17.313
638
2.210
4.790
2.045
3.500
1.023
21.000
18.336
39.336
0.000
0.000
0.000
0.000
0.000
0.000
0.000
0.000
2.210
4.790
18.336
39.336
644
645
640
635
rn
630
625
620
0.0
STAGE / STORAGE
10.0 20.0 30.0
Volume
(ac-ft)
40.0 50.0
10/16/2019N:\Excel Templates\Char-Meck PCCO

B U R T O N BEAM ROAD
E N G I N E E R I N G
CHANNEL PROTECTION VOLUME
COMPUTE CHANNEL PROTECTION VOLUME XPO
S=(1000/CN)-10
S= 0.905
P= 2.58
Q= (P-.2S)^2 /(P + .8S)
Q= 1.74 in.
CPv= 13.920 ac-ft
Release Rate = 4.679 cfs
( Approximate for Static Method)
COMPUTE PERMANENT POOL VOLUME
SIZE THE PERMANENT POOL VOLUME
WQv/PPv = 0.400 ac-ft
Ppvol = 15.400
SIZE PERMANENT POOL SURFACE AREA
sum. Average Depth = 3.0 ft
Surface Area Req'd = 5.133 ac
Area Prov'd = 1.730 ac
at Elev = 637.00
Vol Perm Pool = 16.410 ac-ft (Includes PreBay)
verage Depth Prov'd = 9.49 ft
WQv/PPv Prov'd = 0.38 OK
10/16/2019
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B U R T O N BEAM ROAD
E N G I N E E R I N G
COMPUTE PRETREATMENT VOLUME
Size forebay to treat 0.2 inch/impervious area
Forebay volume is included in the WQv within the permanent pool
Fbvol = 1.280 ac-ft
FbVol Prov'd = 01 000 lac-ft
COMPUTE REQUIRED OUTLET STRUCTURE FOR WATER QUALITY VOLUME
,g Ext. Release Rate = 1.461 cfs
Average Head = 0.6 ft WQv / Surface Area / 2
Orifice = 8.47 Inch
At Elev = 638.20
COMPUTE REQUIRED OUTLET STRUCTURE FOR CHANNEL PROTECTION VOLUME
,g Ext. Release Rate = 4.679 cfs
Average Head = 1.4 ft CPv / Surface Area / 2
Orifice = 12.27 Inch
At Elev = 645.05
ROUTE RUNOFF HYDROGRAPH THROUGH WQ POND
Design Goals:
• Hold min. of 5% of the 1st Inch of runoff within the wq pond for detention time + 1/2 of 6 hour storm
• Hold min. of 5% of the 1 year storm within the wq pond at 24 hrs + 1/2 of 24 hour storm = 36 hours
1.280 AC -FT 0.823 ac-ft
WQv=l 6.160 AC -FT L35.7%
2.660 AC -FT 0.553 Ac-ft
CPv= 13.920 ac-ft 79.2%
10/16/2019
(From HydroCad Summary)
Remaining afterl 2.125 1 Days
(From HydroCad Summary)
Remaining afterl 36 jHrs
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B U R T O N BEAM ROAD
E N G I N E E R I N G
EMERGENCY DRAWDOWN
Vol Perm. Pool = 16.410 ac-ft
Avg Drawdown Rate = 8.273 cfs
Average Head = 4.74 ft
Orifice = 12.03 Inch
FROM ORIFICE CALC'S: USE 14.0 IN DIA ORIFICE
BOUYANCY CALCULATIONS
Top of Col Water =
858.00
Bottom of Col Water =
850.00
Width of Box =
5.00 ft
Length of Box =
5.00 ft
BF= VOLstruct x densityH2O
12,480 Ibs
WT str= 9,400 Ibs
S F= 1 1.2
(Outside Dims)
(Outside Dims)
Weiaht of Structure
Total = 19
10/16/2019
Component
Height (in)
Weight (Ibs)
Base
48
3,000
Riser
36
2,400
Riser
24
1,600
Top
12
2,400
for cohesive soils from A.C.P.A. DD21
qu = 500 Ib/cf for soft clay
Rsliding = A x H x qu / 2
depth = 3 ft, contact with soil
Rsliding = 3,000 lb
WT OF ANCH. REQ'D= 2,576 Ibs
ANCHOR DIMS= L=�ft
W= 4ft
Thickness Reqd= 2.075 ft
Thickness Prov'd = 3 ft
Total WT str = 16,120 Ibs
VOL OF ANCH REQ'D=1 33.2 cf
Compute Combined FS = (WT str + Rsliding) / BF
Combined FS = 1.53 Should be >= 2.0
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