PERMFILE64787

• Permit No: C1981008A
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: NH1 TAB 20 ATTACHMENT C NUCLA MINE AREA RECLAIMED DRAINAGE CHANNEL DESIGN
• Media Type: D
• Archive: Yes

• INPUT CHANNEL K-K' SOURCE
Precipitation 1.60 in 110-yr, 24-hr) NOAA Atlas, Vol. III Colorado
Drainage Area 69.64 ac. Exhibit 20-3
CN 81 Attachment 13-6
L 3450 ft. Exhibit 20-3
Y 2.96 $ (rveighted) Exhibit 20-3
t 0.576 hrs SEDCAD
c
Ba seflow (ditch) 12 cfs Annual monitoring
CHANNEL FACTOR CHANNEL K-K' SOURCE
O 14.'1'1 cfs SEDCAD
Z (side slopes) 5:1 Input
Shape Trapezoidal Input
Bottom width 12 ft Input
Type Vegetated Input
n 0.0715 (avg) SEDCAD
Limiting Velocity 5.0 fps SEDCAD
Slope 0.011 ft/foot Measured
CHANNEL RESULTS Capacity Stability
C D
Normal Depth (dn) 0.93 ft. 0.77 ft.
Flow velocity 7.65 fps 2.12 fps
Channel width (top) 21.3 ft. 19.7 ft.
Results
The reclaimed channel will be a trapezoidal shaped channel with Sh :1v side slopes. This
will insure that farm machinery will be able to traverse the reclaimed field. The
velocity at 2.12 fps is well below the 5.0 fps limiting velocity.
• The adequacy of Culvert C-3 was reanalyzed due to the revised channel and drainage area.
Based on the runoff from the 10-year, 24-hour preci ~i ration event, the existing 24-inch
diameter culvert is adequate. If the field is ever irrigated, then the culvert inlet may
need to be protected due to the increased headwater.