PERMFILE104930

• Permit No: M2000113
• IBM Index Class Name: Permit File
• Doc Date: 8/17/2001
• Doc Name: DRAINAGE STUDY ROARING FORK RESOURCES INC MAMM CREEK SAND & GRAVEL PIT
• Media Type: D
• Archive: No

The estimated storm water runoff for the mining areas excluding the Renewable Resource Area
and the surface facility azea without a pit is:

Existing Condition Runoff, cfs Developed Condition Runoff, cfs
Area 10 yr-24hr 25 yr-24hr 100 yr-24hr 10 yr-24hr 25 yr-24hr ~ 100 yr-24
West End 4.00 8.13 12.49 11.39 18.30 25.83
Dry Creek 1.64 3.44 5.56 7.80 12.71 18.12
Slough to East
Property Line 2.48 5.60 9.37 14.04 22.0 31.51
West Property Line to
Horse Fence 3.27 7.19 12.26 19.86 30.52 43.03
Surface Facility (no
pit) 1.83 3.62 5.52 5.67 9.37 13.51
It is recommended that the storm water runoff from the I-70 corridor be diverted azound the Dry
Creek mining area with a ditch to the slough and that the culvert under the irrigation ditch be
capped during mining. The diversion ditch contains a flatter section from the culvert inlet to the
top of the slough bank and the slough bank. The diversion ditch cross sectional azea for the
flatter section of the ditch is:
Description Feet
Bottom of Ditch 3.00
Depth of Flow 1.90
Ditch Width - Top of Flow 14.40
Ditch Width -Top of Ditch 16.20
Freeboard 0.30
Ditch Side Slope 3:1
Velocity, fps 2.46
The diversion ditch cross sectional azea for the steeper, slough bank section of the ditch is:
Description Feet
Bottom of Ditch 2.00
Depth of Flow I.15
Ditch Width -Top of Flow 8.90
Ditch Width -Top of Ditch 10.70
Freeboard 0.30
Ditch Side Slope 3:1
Velocity, fps 6.27
The shallower sloped ditch should be lined with grass to prevent erosion. The steeper ditch
section on the slough bank should be lined with riprap that is either moRazed in place or a gabion
type construction. An application should be made to the Colorado Department of Transportation
to use the Interstate right of way for the diversion ditch.