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iiiiiiiuiiiiiiiiii <br />999 <br />DIVISION OF MINERALS AND GEOLOGY <br />Drpnnmcnl of Nanual Resources <br />131 3 Shcrm~n C1., Roum ' I i <br />Denver, Colorado 80?U3 <br />Phone: 13171) Hh6-3157 <br />FAX: (3US) N3'~81116 <br />July 1, 1999 <br />Kathleen Welt <br />Environmental Supervisor <br />Oxbow Minine loc. <br />P.O. Box 535 <br />Somerset, Colorado 81434 <br />Re: Update PHC; Technical Revision No. 34, Sanborn Creek Mine, Permit No. C-81-022, <br />Oxbow Mining [nc. <br />Dear Ms. Welt: <br />~`~ ` <br />DIVISION O F i <br />MINERALSi <br />GEOLOGY <br />RECLAMATION <br />MINING•SAFETv <br />Bill Owens <br />Governor <br />Greq E lValche~ <br />EeecW we Dvcao~ <br />nLCnzel e. ions <br />Dinsinn Director <br />The Division is in the process of reviewing the submittal of Technical Revision No. 34. One <br />issue that has been discussed with Oxbow Mining Inc. (OMI), and which is discussed in TR-34, <br />is the potential discharge of 2000 epm of mine water into the North Fork of the Gunnison. The <br />Division would like to address this issue now. The remaining adequacy questions or comments <br />for TR-34 will be forthcoming. <br />OMI is proposing, through Technical Revision No. 34, to discharge mine water into the <br />North Fork of the Gunnison River at the rate of 2,000 gallons per minute. The duration of <br />this rate ofdischarge has not been specified by OMI but has been characterized as occurring <br />over a short period of time. The Division has concerns about this proposed rate of discharge <br />of mine water. <br />The currently approved Probable Hydrologic Consequences (PHC) discussion, found on page <br />2.05-46b of the permit application, states that the PHC will be revised if the mine water <br />discharge shows a "pattern of exceeding 425 gpm averaged over a 7 day period." However. <br />due to the spontaneous combustion problem in the mine, the quality of the mine water may <br />have been degraded. The Division believes that additional safeguards are warranted. <br />A. If OMI intends to discharge mine water at a rate of 2,000 gpm, the Division <br />would like the following information submitted before that discharge rate can <br />be approved: <br />STATE OF COLORADO <br />(]) .4n update of the PHC that provides an estimate of the <br />length of time that this rate of discharge is expected to <br />continue; <br />