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An additional degree of conservatism to the estimate is provided by <br />• this assumption, w1C11 a niinirnwn safety factor of 10 attributed to <br />this assumption. <br />3) Refuse generated from mining of the B seam will consist of waste rock <br />from the immediate roof and floor of the operation ("gob"), and <br />refuse rock generated during development of tl~e access slopes and <br />ventilation shafts for tl~e B seam. Table 1 provides a suniniary of the <br />estimated portion of the refuse pile completed to date with I' scam <br />wastes, and the estimated volumes of refuse to be generated by B seam <br />activities. As can be observed, waste rock generated by the access <br />slopes and ventilation sl~aCts for tl~e B seam represent a very small <br />percentage of tl~e refuse pile. <br />4) The Leacliate discharged to t}ie Nortli Fork is asswned to completely <br />mix with the flow in the river according to tl~e Following equation: <br />Qnf+1*Cal QnfkCnf+Q1'~Clm <br />where: <br />QnF Tlie flow rate of the North Fork (33.9 cfs). <br />Ql -The flow rate of leachate (26 gpin). <br />Qnf+1 Tlie flow rate in tl~e Nortli Fork after leachate I~as <br />_ entered (15,240 gpm). <br />• Cal - Tlie concentration in the Nortli Fork wliicli meets ttie in <br />stream standards (ISS) set by the Colorado Department <br />of Natural Resources (1984). <br />Cnf - Tl~e quality of water in the North Fork upstream of tl~e <br />refuse pile during the flow conditions. <br />Clm -The maximum allowable concentration in the leachate <br />that will meet [he ISS after mixing with the ambient <br />flow in tl~e North Fork. <br />It is estimated that the above assumptions incorporate a miniunnn factor of <br />safety of 100, which is extremely conservative. <br />EXISTING WATER QUALITY OF TIIE NORTII FORK <br />The North Fork of the Cuunison is currently considered a Class I cold <br />water aquatic habitat and a Class II recreation stream. The water is used <br />downstream for both potable water supply and agricultural uses. In stream <br />_ standards (ISS) which account For these uses have been set for tl~e North Fork <br />. 3 <br />