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Mountain Coal Company <br />West EIk Mine <br />Post Office Box 591 <br />Somerset, Colorado 81434 <br />Telephone 970-9235015 <br />September 23, 1997 <br />iiiiiiiiiiiiiiuiii~ <br />999 <br />i~ <br />RECEIVED <br />SEP 2 9 1997 <br /> <br />Divielen of ~~nnerals s GecionY <br />Mr. Michael Boulay <br />Colorado Division of Minerals and Geology <br />1313 Sherman Street, Room 215 <br />Denver. CO 80203 <br />RE: Minor Revision No. 228 (Drill Holes and Piezometers); West Elk Mine; <br />Permit No. C-80-007 <br />Deaz Mike: <br />Mountain Coal Company (MCC) requests a minor revision to drill nineteen (19) bore <br />holes on the West EIk Mine site, to expand the experimental pumping test as <br />presented in MR#226. Twelve (12) holes will be completed as piezometers and four <br />(4) holes will be the experimental pumping wells. Three holes will be core holes. The <br />purpose of this drilling program is to investigate the presence of ground water, which <br />will assist MCC in determining an action plan to dewater areas around the mine site <br />that are contributing to the land slide activity. Please find enclosed one figure which <br />shows the locations of the additional holes (the new holes have been circled on the <br />figure). All holes will be drilled in areas previously disturbed. <br />Continuous Core Hole: Three continuous core hole, to be located near W-3, W-4, <br />and W-5, will be drilled to determine the depth to drill the pumping wells in the area <br />(discussed below) and to determine subsurface conditions. The anticipated depth is <br />200 to 250 feet. The holes will be completed as a 2-inch diameter piezometer with a <br />5-feet screen across the lowest significant transmissive zone. A sand filter pack will <br />be added and the annulus will be grouted to the surface. <br />Pumping Wells: Four pumping wells (in addition to the one pumping well in <br />MR#226) will be drilled using air rotary methods. They will be 12.5-inch diameter <br />open holes. They are identified on the attached figure as W-2, W-3, W-4, and W-5. <br />Piezometers: A maximum of three piezometers will be located at each pumping well. <br />They will also be drilled using air rotary methods, and will be completed as 2-inch <br />diameter piezometers. The piezometers will be screened, and a sand filter pack will <br />be added and the annulus grouted to the surface. <br />The total depths of these holes will not be known until the completion of the core <br />hole. However, they can be expected to be shallower than the core hole. <br />