2008-05-29_REVISION - M1977285

• Permit No: M1977285
• IBM Index Class Name: REVISION
• Doc Date: 5/29/2008
• Doc Name: Drainage report for Sunday Mines Group
• From: Denison Mines
• To: DRMS
• Type & Sequence: AD1
• Email Name: RCO
• Media Type: D
• Archive: No

Section 2
Topaz Mine
To determine the channel capacity, CDM performed a Manning's equation analysis.
Flow depth and velocity were calculated using the following equations for the 100-
year peak discharges, cross section geometry (rectangular), and Manning's n values
listed in Table 2-2.
Q=VA
A = (b + zh)h
2/3
V _ 1.49 (b + zh)h s1/2
n b+2h 1+z2
where:
Q = discharge in cfs
V = velocity in feet per second (ft/ sec)
z: 1 = side slope
A = flow area in square feet (ft2)
b = bottom width of the cross section in feet (ft)
h = flow depth in ft
S = channel slope in feet/feet (ft/ft)
n = Manning's roughness coefficient (unitless)
. .._1.- 9- r-h-nnMe 4 nnel 2 Capacity Analysis
i axle z-z in u t values 101 U .a••••?•? -•.- _ __ __--
b
Channel 100- r Q S n z ft
cfs ftift ft/ft
1 5.79 0.025 0.035 3 3
2 4.25 0.037 0.035 3 3
The calculated channel depths and velocities of Channels 1 and 2 are shown in
Table 2-3. CDM recommends adding 2-feet of freeboard to the calculated flow depth
to account for potential channel overtopping. Given rectangular channels with bottom
widths of 3 feet each, a design depth of 2.5 feet is recommended for Channels 1 and 2.
for Channels 1 and 2
i aale z-s Laiu ulatlon Summ
h a
Freeboard
Design Depth
V
Channel
ft ft ft fUsec
1 0.43 2 2.43 3.16
2 032 2 2.32 3.30
To determine the appropriate channel lining (e.g., vegetated or riprap) for Channels 1
and 2, CDM calculated flow velocities using information from the Urban Drainage
and Flood Control District (UDFCD) Drainage Criteria manual (UDFCD 2005).
UDFCD recommends flow velocity be less than 5 feet per second (ft/sec) for grass-
lined channels and velocities less than 12 ft/ sec for riprap channels (UDFCD 2005).
Based on UDFCD recommendations, a Manning's n value of 0.035 was selected for
design calculations to check the capacity of grass-lined channels. Based on these

2-3
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