REP19893 - Laserfiche WebLink

Home Browse Search

0 March 18, 1996 Colowyo Coal Company L. P. 5731 State Highway 13 Meeker, CO 84641 Attention: Mr. Jim Kiger Subject: Sealing of X-Seam Auger Mining North Wall, West Pit Colowyo Coal Mine, Moffat County, Colorado Job No. 23,585 Dear Mr. Kiger: This letter is in response to the State of Colorado, Division of Minerals and Geology comments regarding their concern for sealing or covering the X-Seam auger openings along the north wall of the west pk. The concern is that water entering the auger holes could affect the Excess Spoil Pile and previously repaired landslide area located south of the west pit pond. Attached as Appendix "A" is a previous letter by CTLlfhompson (Job No. 23,001, dated July 6, 1995) which addresses this concern. As shown on the attached letter, based upon information provided by Colowyo, the Y-2 coal seam outcrops in the area of the previous landslide and toe of the Excess Spoil Pile area. The X-seam is approximately 70 to 80 feet below the Y coal seams and we do not believe that the X-seam outcrops in the area of concern. Another factor is the elevation of proposed drain outlets within the reclaimed west pit. The drain beneath the excess spoil pile will be above the X-seam. Another outlet drain is planned in the East Taylor drainage wkh an outlet elevation of 6990 The lowest elevation of the X-seam along the north wall is approximately elevation 7010 which is above the second outlet drain. Based upon this configuration we do not believe that water will build up within the reclaimed west pk above elevation 6990 and should, therefore, not impact the X-seam auger holes. We understand as a precaution Colowyo is planning to place a zone of claystone/shale fill along the face of the north wall, X-seam auger holes. The overburden material will be placed as a shallow dump with compaction by 240 ton haulage truck traffic, To summarize, we believe our previous recommendations to provide a clay seal at each coal seam location (in our geotechnical investigation for the west pit excess disposal sRe, Job No. 16,516, dated March 1, 1991) can be rescinded based upon the more detailed information currently available on the mine plan. As outlined in our July 6, 1995 letter, coal seams which are being considered for angering (X, C, D, and/or E) do not outcrop near the previous landslide area or Excess Spoil Disposal area. The X-seam is above the proposed drain outlet to East Taylor Creek. Based upon these configurations we do not believe that sealing or covering of the auger holes for any of the seams is required. CTL/THOMPSON, INC. CONSULTING ENGINEERS 1971 WEST 12TH AVENUE ~ DENVER, COLORADO 80204 ~ (303) 825-0777