PERMFILE118274

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 11/16/2006
• Section_Exhibit Name: 2.05.5 & 2.05.6 Post-Mining Land Uses and Mitigation of Surface Coal Mining Operation Impacts
• Media Type: D
• Archive: Yes

West Elk Mine
• If subsidence impacts do occur along a stream channel such as Dry Fork, mitigation
measures will be implemented to limit and control the interruption of flows, as described in
Section 2.05.6(6)(f)(iv)(A-D). In addition, the Minnesota Creek augmentation plan will
protect downstream water users from potential loss of streamflows due to mining activities.
• The only reservoir located neaz the permit azea is Minnesota Reservoir. The longwall panel
layout has been designed to keep the reservoir outside of even the most conservative angle
of draw. Therefore, no subsidence effects will be seen at the reservoir.
• The most likely water quality impacts to surface water as a result of subsidence is the
increase in stream erosion rates. However, the projected changes in stream channel slopes
aze estimated to result in changes in sediment load of less than five percent.
• Mine water discharges aze anticipated to continue to follow historic patterns. Even with the
encountering of the BEM and 14HG fault inflows, the salinity loading to the North Fork has
been within the projected value assigned to the mine in the CHIA.
• Groundwater quantity effects due to mining involves the caved/fractured zone intercepting a
water bearing unit overlying the coal seam. Due to the lenticulaz nature of the sandstones in
the Mesaverde Formation, this phenomenon typically results in initial inflows of 10 to 15
gpm and the flow tapering off to a trickle within a couple of weeks. The nature of the
groundwater occurrence has also led to a lack of water supply wells in the permit area.
• The BEM and 14HG faults are exceptions in that they contained lazge volumes of water,
which resulted in very high initial inflow rates and sustained flows. Analyses by MCC and
its consultants has shown the residence time of these waters to be on the order of 10,000
years. The fault inflows have been decreed in water court asnon-tributary water; therefore,
the interception of the water has not adversely impacted any groundwater users in the area.
Groundwater quality effects can occur as a result of fractures allowing water to migrate
between geologic units. The practical significance of this phenomenon in the permit azea is
minuscule due to the scazcity of water in the formation and the lack of water supply wells in
the vicinity.
Sur/ace Water Quantity Effects
As discussed in Section 2.04.7, surface water resources have been studied extensively by MCC
since 1976. Map 34 and Table 5 shows the existing hydrologic monitoring network. The surface
water monitoring network at West Elk Mine consists of the following:
1. Streamflow and/or water quality monitoring stations on the North Fork upstream (USGS) and
downstream of the mine, Sylvester Gulch, Dribble Gulch, Upper and Lower Minnesota
Creek, Lick Creek, Dry Fork (Upper, Middle, and Lower), Horse Gulch, East Gulch east of
Horse Gulch, Deep Creek and Box Canyon. No stations were placed on Raven Creek as a result
of a subsidence protection zone stipulated in the Lease and EA.
2.05-786 Revised June 2005 PR/0, January 2006, March 2006; Rev. May 2006 PRI G