2013-09-27_REVISION - M1979094HR ‎(3)‎

• Permit No: M1979094HR
• IBM Index Class Name: Revision
• Doc Date: 9/27/2013
• Doc Name: AM01 Drainage Design
• From: Cotter Corp
• To: DRMS
• Type & Sequence: AM1
• Email Name: DMC
• Email Name: TC1
• Media Type: D
• Archive: No

JD -7 Mine — Drainage Design Plan 32
4.4.1 Pit Diversion Ditch —West
The Pit Diversion Ditch West (PDW) diverts stormwater from upslope around the existing JD -7 Open Pit
and routes it westward into a natural channel in the adjacent sub -basin N -E. The PDW was constructed in
1980 and has been improved and maintained in subsequent decades. The PDW has achieved a relatively
stable channel configuration over time, and is 1,144 ft in length with an average bed slope of 0.0213. The
excavated channel has a broad floor (10 to 20+ ft) and top widths range from 23 ft (measured) to over 35
feet (visual estimate). The channel has shallow sloping sides with an average slope of 4.6:1 based on field -
measured profiles4 (Figure 14, Figure 15). Based on the measured channel profiles, the PDW was modeled
with a 2.2 -ft bottom width and 4.6:1 ft side slopes in the WinTR -55 model. The channel is normally dry,
and flows only in response to precipitation events.
F_ 0.00
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Distance (ft)
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Distance (ft)
Figure 14. Channel Profiles Measured in Pit Diversion West
4 Channel side slopes were measured at 5.3:1 and 4.3:1 for the left bank and right bank of Profile PDW -1, and at 5.6:1 and 3.1:1 for
the left bank and right bank of Profile PDW -2.
4149A.130926 Whetstone Associates •