27-55 E&SC calculations 20201216

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Dewatering Settling Basin &
Outlet Control Structure Calculations
r,ECEIVED
DEC 16 ON
LAND QUALITY
MINING PROGRAM
Project
BALLANCE TRACT MINE
Moyock Township, Currituck County, North Carolina
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Prepared By. •�� NG►XX
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Bissell Professional Group ��11 11►►���
P.O.Box 1068
3512 N.Croatan Highway
Kitty Hawk, North Carolina 27949
December 8,2020
P.O. Box 1068 . 3512 N. Croatan Hwy. • Kitty Hawk, NC 27949
252-261-3266 • Fax: [phone] • E-mail:bpg@bisselI profess ionalgro up,corn

ENCLOSURES
• Dewatering Settling Basin Design Calculation(Basin Sizing for 1,000 GPM pump)
• Outlet Control Structure—Inlet Weir Calculation(Weir Sizing for 1,000 GPM pump)
• Outlet Control Structure—Outlet Pipe Calculation(Velocity check for 1,000 GPM pump)

Dewatering Basin Design *items in red are Inputs
Version 2.27.09
e volume of the borrow pit dewatering basin will be basedon a 2 hour retention time. Using
the formula V= 8.0203 * Q* t where,V is volume in cubic feet,Q is the pump rate in gallons per
minute(GPM),and t Is the retention time in hours.The pump rate is not to exceed 1,000 GPM
(60,000 GPH .
STEP 1: Input required variables The volume of the borrow pit dewatering
basin will be based on a 2 hour retention
Pump Rate: 1000 GPM time. The pump rate shall not exceed
Retention Time: 4 hours 1,000 GPM (60,000 GPH). The contractor
may desire a greater retention time for
Required Volume: 32081.2 fe managing turbidity; however, work
associated with this increased volume will
be considered incidental.
STEP 2: Design of the Dewatering Basin
Final Required Volume: 32081.2 ft'
Design Depth: 3 *not to exceed 3 feet
Proposed Basin Side Slopes: 3.0 :1 side slopes `must be at least 1.5:1 or flatter
OPTIONS
2:1(L: 3:1{L:M
Suggested Top Width ft : 74 60
Suggested Top Length (ft): 148 180
Final Design Top Width Ift): 75 60
Final Design Top Length (ft): 150 180
Final Design Depth (ft): 3 3
Verity storage(ft) 2{7899.00 26244.00
Too Low Too Low
The dewatering basin shall be designed in accordance with the Borrow Pit
Dewatering Basin Detail Drawing.
Comments:
Settling dasin designed to serve dewatering of Ballance Mine

Weir Report
Hydraflow Express Extension for Autodesk®Civil 3138 by Autodesk,Inc. Tuesday,Dec 8 2020
BALLANCE SETTLING BASIN - OCS FLASHBOARD WEIR
Rectangular Weir Highlighted
Crest = Sharp Depth (ft) = 0.37
Bottom Length (ft) = 3.00 Q (cfs) = 2.220 (Ijow(OM
Total Depth (ft) = 0.50 Area (sqft) = 1.10
Velocity (ft/s) = 2.02
Calculations Top Width (ft) = 3.00 f
Weir Coeff. Cw = 3.33
Compute by: Known Q
Known Q (cfs) = 2.22
Depth (ft) BALLANCE SETTLING BASIN - OCS FLASHBOARD WEIR Depth (ft)
�Lku
1.00 1.00
0.50 0.50
0.00 0.00
-0.50 -0.50
0 .5 1 1.5 2 2.5 3 3.5 4
Weir r-r— W.S. Length (ft)

Culvert Report
Hydraflow Express Extension for Autodesk®Civil 3138 by Autodesk,Inc. Tuesday,Dec 8 2020
BALLANCE SETTLING BASIN - OCS OUTLET PIPE
Invert Elev Dn (ft) = 1.00 Calculations
Pipe Length (ft) = 40.00 Qmin (cfs) = 2.22
Slope (%) = 0.25 Qmax (cfs) = 2.22
Invert Elev Up (ft) = 1.10 Tailwater Elev (ft) = (dc+D)/2
Rise (in) = 24.0
Shape = Circular Highlighted
Span (in) = 24.0 Qtotal (cfs) = 2.22
No. Barrels = 1 Qpipe (cfs) = 2.22 (;coo G014)
n-Value = 0.010 Qovertop (cfs) = 0.00
Culvert Type = Circular Culvert Veloc Dn (ft/s) = 1.07 < 2-1
Culvert Entrance = Smooth tapered inlet throat Veloc Up (ft/s) = 3.45 1,01-J-
Coeff. K,M,c,Y,k = 0.534, 0.555, 0.0196, 0.9, 0.2 HGL Dn (ft) = 2.26 ��b'✓�^
HGL Up (ft) = 1.62
Embankment Hw Elev (ft) = 1.83
Top Elevation (ft) = 4.50 Hw/D (ft) = 0.36
Top Width (ft) = 20.00 Flow Regime = Inlet Control
Crest Width (ft) = 9.00
Bev(N BALLANCE SETTLING BASIN-OCS OUTLET PIPE Ha OBO(W
6.00 3s0
4.00 in
2.00 p,00
d
.010
0.00 .1 10
0 5 10 16 20 25 30 35 40 e5 60 65 60
VrerdarCWvert HGL Embank
Reach(R)