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J. E. STOVER & ASSOCIATES <br />2768 COMPASS DRIVE, SUITE 101 <br />GRAND JUNCTION, COLGFiADO 81506 <br />PHONE: (970) 245-4101, FAX 242-7908 <br />MINE ENGINEERING <br />MINE RECLAMATION <br />January 26, 2001 <br />David Berry <br />Division of Minerals and Geology <br />1313 Sherman St., Room 215 <br />Denver, CO 80203 <br />Re: Powderhorn Coal Company <br />Permanent Mine Water Plan <br />Technical Revision No. 33 <br />Permit C-81-041 <br />CIVIL ENGINEERING <br />CONST. MANAGEMENT <br />RECEIVED <br />JAN 2 g 2001 <br />Division of Minerals 6 Geolow <br />Dear Mr. Berry: <br />By letter dated January 23, 2001, the DMG <br />regarding the referenced technical revision. <br />comments and concerns: <br />transmitted additional adequacy comments <br />Following are PCC's responses to the DMG's <br />PCC has two sources of information available to determine the mine water inflow <br />to the Northwest Intake Pool as follows: <br />a. Mine Discharge -The siphon system has been in operation from 1993 - <br />2000. During this period of time there was discharge from Outfall 001 <br />located near the conveyor tube, Outfall 002 the siphon, and there was <br />consumptive use of water by the underground mine and preparation plant <br />through 1999. The average flow values each year are fairly consistent <br />ranging from 200 gpm to 300 gpm with an average of about 250 gpm. <br />b. Mine Inflow Studies -Mine inflow studies at the South Portal were performed <br />from 1986 through 1999. These point in time measured values range from <br />110 to 350 gpm with an average of about 225 gpm. <br />Based on the above data, PCC believes a 350 gpm design flow rate for the North <br />Decline discharge pipe is appropriate. <br />The South Portal has two discharge points, the siphon and the South Portal 4-inch <br />diameter pipe, Outtalls 002 and 001 respectively. If both of these discharge points <br />were left unattended, flowing at full capacity, the water level in the mine would be <br />reduced to the point the siphon would break and stop discharging at least <br />temporarily. The capacity of the siphon is close to the mine inflow rate. Therefore, <br />