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Peabody <br />Twentymile Coal Company <br />RSC1-=,'VED <br />Mrs. Janet Binns JUL 0 2 2009 <br />Environmental Protection Specialist Div,s,(,,, u <br />Colorado Division of Minerals and Geology Mining and 1313 Sherman Street, Room 215 Safety <br />Denver, Colorado 80203 <br />(303) 866-4933 <br />29515 Routt County Road #27 <br />Oak Creek, CO 80467 <br />970.879.3800 <br />June 30, 2009 <br />RE: Twentymile Coal Company - Foidel Creek Mine (Permit No. C-82-056), Minor Revision <br />(MR09-238) for 10-Right Monitoring Borehole and Miscellaneous Facilities <br />Dear Mrs. Binns: <br />Twentymile Coal Company (TCC) requests CDRMS approval of a Minor Revision (MR09-238) to the <br />approved Permit, for drilling and installation of a new monitoring borehole at the 10-Right Mine <br />Dewatering location. This revision also address construction or modification of several minor facilities, <br />including expansion of the existing 10-Right Pumphouse, a new propane tank installation near the new <br />Washplant II, installation of a temporary contractor maintenance/storage shed near Mine Substation No. <br />1, installation of temporary skid-mounted material storage units east of the Area 1 Pit, and a change in the <br />configuration and use of a portion of Ditch D-4. The new monitoring borehole is needed to provide for <br />ongoing monitoring of mine water levels in the Eastern Mining District. The other minor facilities are <br />needed to support ongoing mining and related operations. The proposed or modified facilities are shown <br />on Map 24, Surface Facilities and Freshwater Systems, with details provided by drawings in Exhibit 49P. <br />The new 10-Right Monitoring Borehole will be drilled on the existing 10-Right facilities pad, and will <br />involve no new surface disturbance. The borehole will be collared with an 8-inch ID surface casing, <br />extending to a depth of approximately 40 feet. The borehole will then be drilled as a 6.25-inch borehole <br />to a depth of approximately 1,365 feet, and cased with 3-inch ID cemented in-place casing. The casing <br />will extend approximately 4 feet above the ground surface, and be fitted with a locking cap to prevent <br />unauthorized access. The 10-Right Monitoring Borehole will be used for regular monitoring of mine <br />water levels in the Eastern Mining District. <br />In order to better accommodate pumping and control equipment for the two 10-Right Dewatering <br />Boreholes, the existing 10-Right Pumphouse and pad will be demolished and replaced with a larger <br />Pumphouse and foundation pad with support piers. Specifically, the existing 16 x 14 foot wood-frame <br />building and 14 x 24 foot concrete pad will be replaced by a 25 x 43 foot concrete pad with 12 - 1-foot <br />diameter concrete piers extending to a depth of approximately 12 feet, and a 25 x 30 foot pre-fabricated <br />steel building. The Pumphouse expansion will occur on the existing 10-Right facilities pad and will <br />involve no new surface disturbance. Other associated work will include placement of the existing <br />electrical transformer on the northeast corner of the new pad, and completion of the necessary plumbing <br />and electrical hook-ups. <br />G:\Environmental\REVISION\MINOR-RV\MR09-238 1 ORT Borehole & Misc\MR09-238 1 ORT Borehole and Misc TL.doc