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<br />' William J. Carter Mazch 12, 1998 <br />Re: Response to Susan Burgmaier's comments on the 1996 Annual Hydrologic Report <br />The time and expense of collecting, storing, and presenting this large volume of data in not <br />insignificant. Sanbom Creek Mine questions if this time and expense, for the benefit of a few <br />' individuals in the Division of Minerals and Geology who may review the data, is justified. <br />Comment 11. <br />' "Tn future reports, OCM should be including a discussion of the hydrologic data being reported in <br />the AHR. Trends which are apparent in the data should be discussed, as well as possible <br />' explanations for any apparent anomalies. Such discussion should compare monitoring results to the <br />prediction of probably hydrologic consequences set forth in the approved permit application <br />package. Rule 4.05.13(4)(c)(iii) states that the annual hydrologic report, if required by the <br />' Division, should include a written interpretation of the data and identification of mining related <br />impacts to the hydrologic balance. Accordingly, the Division will require said discussion in future <br />reports." <br />i Response 11. <br />My response to the Division of Minerals and Geology requirement for a written interpretation of <br />' the data and identification of mining related impacts to the hydrologic balance remains as: There <br />has not been, nor are there expected to be, any significant negative mining-related impacts to the <br />hydrologic balance. This conclusion was reinforced by the "Aquatic Impairment Study of the <br />' Sanborn Creek Mine Discharge, Somerset, Colorado" by John C. Emerick, Nevis E. Cook, and <br />Susan M. Hoffineister, January 30, 1995. This report was submitted with the 1995 Annual <br />Hydrologic Report. <br />Many of the questions asked, particularly in regards to the total dissolved solids in the mine water <br />' discharge and the Rollins Sandstone, for the 1996 Annual Hydrologic Report have been previously <br />discussed. If necessary, the discussion will be repeated each yeaz. <br />Prediction of Probable Hydrologic Consequences for the Sanborn Creek Mine set forth io the <br />approved permit application package in Section 2.05.6(3)(b)(iii), page 2.05-46a to 2.05-466, <br />' Rev: 9/12/97, MR-45: <br />"It is assumed that the Somerset Mine will eventually fill to a level where the water inflow to the <br />' mine equals that which is leaching out of the mine through the alluvium. In this case, the primary <br />impact of the Somerset Mine discharge through the alluvium on the Gunnison River is on its total <br />dissolved solids (TDS) concentration. The flow into the mine is estimated to be 235 gallons per <br />' minute according to the Mine [nflow Study dated September 21, 1990. The average TDS <br />concentration of the water monitored in H-10 and B-6, through 1989, is 3176 and 2286 mg/liter <br />' respectively which averages 2731. The average TDS concentration of the North Fork of the <br />Gunnison River, near Hubbard Creek, in 1981 was 151 mg/liter (CT.S. Steel Mining Co. data). <br />' 24 <br />XBOW MINING INC. <br />1 <br />