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2022-09-29_PERMIT FILE - C1980007 (2)
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2022-09-29_PERMIT FILE - C1980007 (2)
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Last modified
10/6/2022 2:39:13 PM
Creation date
10/6/2022 2:29:35 PM
Metadata
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Template:
DRMS Permit Index
Permit No
C1980007
IBM Index Class Name
Permit File
Doc Date
9/29/2022
Doc Name
pg 2.05-200 to 2.05-300
Section_Exhibit Name
2.05.6 Mitigation of Surface Coal Mining Operation Impacts Part 2
Media Type
D
Archive
No
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West Elk Mine <br />• From mid-November 1996 through 2003 the inflows maintained a relatively constant <br />inflow rate of about 80 gpm. Assuming that the rest of the mine had inflows similar to <br />previous years (i.e., 12 gpm or 19 acre-feet per year), the cumulative inflows to the mine <br />from groundwater in 1996 totaled approximately 320 acre-feet (averaged over the year, <br />this is equivalent to about 200 gpm). MCC knows of no detrimental impacts to <br />groundwater users in the region due to claimed reliance on this groundwater. <br />2. 145E Headgate Fault (a.k.a. 14HG Fault) - In mid-January 1997, while development <br />mining the #3 entry near cross-cut #11 of the 145E Panel Headgate, a southwest to <br />northeast-trending fault (similar in orientation to the BEM Fault) was encountered <br />which produced approximately 100 gpm, primarily from the floor. On January 20, <br />1997, development mining was occurring in the #2 Entry between cross-cut #10 and #11 <br />when a massive inflow of more than 8,000 gpm entered the mine from the floor with <br />enough force to lift the water to the roof. The water temperature was approximately <br />88°F. The inflow dropped to approximately 2,700 gpm within a week and to 1,750 gpm <br />a few days later. By April 1997, inflows from the 14HG Fault system had decreased to <br />approximately 200 gpm. Similar to the BEM fault system, in September 1998 when the <br />14HG Fault system was mined through in the 145E Tailgate, the headgate inflow dried <br />and the inflow began in the tailgate entries. In August 2003, development mining <br />penetrated the 14HG Fault at cross-cut #32 of the 225E Headgate producing an initial <br />inflow rate of about 100 gpm that rapidly declined to approximately 35 gpm. <br />• Until the spring of 1996, when the BEM Fault system was encountered, there had been no reason <br />to plan for the managing of lazge mine groundwater inflows. With the unexpected production of <br />several thousand gallons of water from both the BEM and 14HG fault systems in the B Seam <br />workings, the need for more rigorous water management and planning had arisen. MCC has <br />worked proactively to ensure that unexpected mine inflows can be managed without <br />compromising safety, operations or environmental requirements. Examples of the proactive <br />efforts undertaken at that time, and still in place today, include: <br />• Utilizing previously-mined down-dip azeas as large capacity sumps. The NW and NE Panels <br />sealed sumps have historically been used for this purpose (see discussion later in this <br />section). <br />• Development mining has proceeded in a measured and cautious manner in the eastern portion <br />of the B Seam mine workings. Mining plans have been revised and developed to include <br />procedures for the encounter of additional water-bearing faults. As a result, MCC is <br />prepared to mobilize rapidly to control additional groundwater inflows should they <br />occur. <br />• MCC has installed numerous pumps and miles of pipeline in the mine to manage inflows in <br />accordance with the mine water management schematic on Figure 22. <br />Borehole lithologies and stratigraphic correlations, both locally and regionally, have been <br />• thoroughly scrutinized to assess whether there are indications of other fault systems. The <br />result of this assessment has shown that there are as many as four known or inferred <br />2.05-152 Revised June 2005 PRIO; Rev. March 2006; Rev. May 2006 PRIG <br />
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