4 - 13-04 ADI Response - AWCK Plunge Pool Calcs.pdf

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GOLD HILL QUARRY
2020 MINE PERMIT MODIFICATION
SLOPE DRAIN PLUNGE POOL CALCULATIONS
FOR
VULCAN CONSTRUCTION MATERIALS, LLC
CABARRUS/ROWAN COUNTY, NORTH CAROLINA
alley, williams, carmen, & king, inc.
ICONSULTING ENGINEERS
FIRM LICENSE No. F-0203
120 SOUTH MAIN STREET P. O. BOX 1248
KANNAPOLIS,NC 28082 704/938-1515
PROJECT NO. 11526
July 10, 2020
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Slope Drain Plunge Pool Calculations:
Project: 11526 Gold Hill Quarry 2020 Mine Permit Modification
Date: 7-10-20
The plunge pool size is based on a maximum drainage area of 2.2 acres and a 10 year flow.
Q10 = CIA= 0.5x7.3x2.2 = 8.Ocfs
The size of the plunge pool is based on a SCS design outlined in a design note report (Design
Note No. 6, (Second Edition)) for Riprap Line Plunge Pools For Cantilever Outlet, dated March
5, 1986. The methodology was used to create a spreadsheet, which was developed by D. Hurtz,
Midwest NTC, 1/90 and modified by M. Dreischmeier, Eau Claire TC, Wis., 3/98. Version 8.99
of the spreadsheet was used.
The design of the pool was based on the following values:
Pipe Slope: 7%
Pipe Size: 18 Inches
Pipe Invert 100.25
Pool Tailwater Elevation: 100.00
Downstream Channel Elev.: 100.00
Invert Height above pool: 0.25 feet
Flow: 8.0 cfs
The downstream tailwater and channel invert were assumed to be the same elevation since the
plunge pools are not being installed is a defined stream.
alley, williams, carmen & king, inc. am
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RIPRAP LINED PLUNGE POOL FOR CANTILEVER OUTLET (Version 8.99)
(Reference Design Note No. 6 (Second Edition), Jan. 23, 1986
JOB:
DESIGNER: Date: 7/10/2020
CHECKER: Date:
INPUT DATA:
Conduit Diameter D = 1.50 ft
Conduit Discharge: Q = 8.00 cfs
Conduit Slope at Outlet: S = 0.07 ft/ft
Conduit Outlet Invert Elevation: El, CO = 100.25 ft
Tailwater Elevation: El, TW= 100.00 ft
Outlet Channel Invert Elevation: El, CH = 100.00 ft
Water Density: RHO = 1.00
Bed/Riprap Particle Density: (Default 2.64) RHOS = 2.64
D, 50 Riprap Size: RS = 0.33 ft
Riprap Thickness: (2.5*D, 50 recommended) RT= 0.83 ft
Bedding Thickness: (6 inch min. rec.) (Enter 0 for geotextile) BT= 0.00 ft
Side Slope Ratio: Zw= 3.00 ft/ft
Upstream End Slope Ratio: Zlu = 3.00 ft/ft
Downstream End Slope Ratio: Zld = 3.00 ft/ft
Combined End Slope Ratio: Z1 = 3.00 ft/ft
OUTPUT---POOL LOCATION AND DIMENSIONS:
Vert. Dist. from Tailwater to Conduit Invert: Zp = 0.25 ft
Submergence Check: (If Zp < 0 , Use Zp = 0) Use Zp = 0.25 ft
Beaching Check: [Q/(gDA5)^0.5 <_ (1.0+25*D,50/D)] O.K.
**Beaching Controlled**
Distance from Conduit Exit to C/L Pool: Xm = 1.93 ft
Pool depth at C/L Below Conduit Invert: Zp+0.8Zm = 1.29 ft
Pool Bottom Elev: EI,PB= 98.96 ft
Pool Bottom Length: 2Lr2 = 0.87 ft
Pool Bottom Width: 2Wr2 = 0.82 ft
Upstream Pool Length at Tailwater Elev.: Lru = 3.57 ft
Downstream Pool Length at Tailwater Elev.: Lrd = 3.57 ft
Pool Width at Tailwater Elev.: 2Wr= 7.09 ft
Check Side Slope Ratio: (Wr>=We) O.K.
**Side Slope Ratio Zw O.K.**
Check Min. End Slope Ratio: (Lru & Lrd >= Le) O.K.
**End Slope Ratios O.K.**
Check Upstream Length: (Lru >=Xm) O.K.
**End Slope Ratio Zlu O.K.**
Pool Bottom Elev. at Bottom of Riprap: El, BR= 98.13 ft
Pool Bottom Elev. at Bottom of Bedding: El, BB = 98.13 ft
OUTPUT---VOLUMES BELOW WATER SURFACE ELEVATION:
Volume of Excavation (measured from bottom
surface of bedding): V,pbs = 3.9 cu yd
Volume of Rock Riprap: V,rs = 3.1 cu yd
Area of Geotextile: A,gt= 23.3 sq yd
Spreadsheet developed by D. Hurtz, Midwest NTC, 1/90
Spreadsheet modified by M. Dreischmeier, Eau Claire TC, Wis., 3/98
Design Note No. 6 (Second Edition), Jan. 23, 1986

RIPRAP LINED PLUNGE POOL FOR CANTILEVER OUTLET
Reference Design Note No. 6 (Second Edition), Jan. 23, 1986
Elev. 100.3 q Elev.
100.0
Elev.
1.3 99.0
0.9
1 1
3.0 3.0
�- 1.9 —�
3.6 6.2
SECTION A-A
' 12.3
7.1
.-- 0.8 1
0.8 3.0
�-- 1.1--► SECTION B-B
B
A A
ROCK GRADATION
% Passing Size (in) B
100 7.92
60-85 5.94 LANDOWNER
25-50 3.96
5-20 1.98 DESIGNER:
0-5 0.792 SHEET OF