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Mountain Coal Company <br />West Elk Mine <br />Post Office Boz 591 <br />Somerset, Colorado 81434 <br />Telephone 970.929.5015 <br />September 12, 1997 <br />Mr. Michael Boulay <br />Colorado Division of Minerals and Geology <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203 <br />I-ti,-„cIVcD <br />SEP 2 4 1997 <br />pivision of rvunerals is Uecic9Y <br />iii iiiiiiiiniii iii <br />999 <br />~~ <br />RE: Minor Revision No. 226 (Drill Holes and Piezometers); West Elk Mine; <br />Permit No. C-80-007 <br />Dear Mike: <br />Mountain Coal Company (MCC) requests a minor revision to drill eleven (11) bore <br />holes on the West Elk Mine site. Ten holes will be completed as piezometers and one <br />will be an experimental pumping well. The purpose of this drilling program is to <br />investigate the presence of ground water, which will assist MCC in determining an <br />action plan to dewater areas around the mine site that are contributing to the land <br />slide activity. Please find enclosed three figures which show the locations of the holes <br />in plan view and in cross-section. The third figure shows across-section of the nested <br />piezometers. All holes will be drilled in areas previously disturbed. Only minor <br />blading to reach the location of the holes will be required. The blading will also occur <br />in areas previously disturbed. <br />Continuous Core Hole: A continuous core hole (rock piezometer) will be drilled near <br />the substation to determine the depth to drill the pumping well (discussed below) and <br />to determine subsurface conditions. The anticipated depth is 200 to 250 feet. The <br />hole will be completed as a 2-inch diameter piezometer with a 5-feet screen across the <br />lowest significant transmissive zone. A sand filter pack will be added and the annulus <br />will be grouted to the surface. <br />Air Rotary Holes: Three holes (rock piezometers and well) will be drilled using air <br />rotary methods. One will be a 12.5-inch diameter open hole that will be located <br />approximately 30-feet from the core hole. This will be a test pumping well. <br />The other two air rotary holes will be completed as 2-inch diameter piezometers. The <br />piezometers will be screened, and a sand filter pack will be added and the annulus <br />grouted to the surface. <br />