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 6
Sunday Mine
r..l.l.. a 45 1...a.4 11.1..- fns rhannal 4 rnnacity Analvsis
100-yr Q S z b
Channel cfs ft/ft n ft/ft ft
1 19.61 0.016 0.035 3 0
The calculated channel depth and flow velocity of Channel 1 are shown in Table 6-3.
CDM recommends adding 2-feet of freeboard to the calculated flow depth to account
for potential channel overtopping. The design depth of 3.5 feet is recommended for
Channel 1.
rohla AA ralrldatinn Summary for Channel 1

Channel h
ft Freeboard
ft Design Depth
ft V
ft/sec
1 1.29 2 3.29 3.90
CDM used the UDFCD Drainage Criteria manual and calculated flow velocities to
determine the appropriate channel lining for Channels 1 (UCFCD 2005). UDFCD
recommends flow velocity be less than 5 ft/sec for grass-lined channels and 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 criteria, CDM recommends a grass-lined
channel for Channel 1 since the flow velocity is less than 5 ft/ sec.
6.4.2 Berm Design
CDM designed earth berms to capture surface water runoff from Basins 2 through 7.
Runoff in Basins 2 trough 5 will be captured by a berm along the crest of the WRA.
Runoff in Basins 6 and 7 will be captured and routed to proposed catchment basins
(refer to Exhibit E-1). The berms and catchment basins were designed to contain
runoff from the 100-year, 24-hour storm event. The point precipitation frequency
estimate for the 100-year; 24-hour storm, obtained from NOAA Atlas 14, Volume 1 for
Colorado (NOAA 1973) is 3.0 inches. CDM used the SCS runoff equation to estimate
runoff from the 3.0 inches of rainfall. The SCS runoff equation is:
(P - 0.2s)Z
Q - (P + 0.8s)
where
Q = runoff (in)
P = rainfall (in)
S = potential maximum retention after runoff begins (in)

6-3
0;\64988- Denison\Task Order 1 - Sunday Mines Drainage StudyV2ep0r8Final Report\Final Sunday Mines Drainage Repod_052208.doc