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<br />t BATTLE MOUNTAIN RESOURCES, SAN LUIS PROJECT <br /> CMLRD ADEQUACY LETTER RESPONSES <br /> Page 18 of 28 <br /> <br /> 31. The water balance calculations are referred to on pages D-73, D-74, <br /> and 6-3 as being found in Appendix I. The apparent correct reference <br />is Appendix K. <br /> RESPONSE: The correct reference for the water balance is Appendix K. Pages D- <br /> 73, D-74, and G-3 have been revised to show the correct reference. <br /> 32. The units for monthly shallow lake evaporation are referenced in <br /> Appendix K as "miles". The apparent correct reference would be <br />' inches. <br /> RESPONSE: The first page of Appendix K has been corrected to read inches as <br />' the unit for monthly shallow lake evaporation. <br /> 33. A pan evaporation coefficient of 0.70 was used in the water balance <br /> whereas 0.74 was given in Exhibit K of the original permit. Piease <br />' clarify. <br />RESPONSE: The pan evaporation coefficient of 0.74 was used in the water balance <br />calculations for treatment of ore in a heap leach facility. The <br />current ore treatment process involves closed cell leaching coupled <br />with deposition of spent ore in a tailings facility. Use of the lower <br />' coefficient is more conservative than that of 0.74. <br />34. The diversion ditches located upslope from the collection pond are <br />1 shown in cross-section on Detaii 2 of Figure C-8 and in plan form <br />on Figures C-3 and C-4. No peak flow calculations are provided to <br />substantiate their design, however the size appears to be <br />conservative. Please provide the following information on each <br />' diversion: <br />a. The upland drainage area; <br />' b. The minimum slope to ensure drainage; <br />c. An estimate of the size of runoff event which would overtop <br />the berm; and <br />d. The erosion control measures to be utilized at the ditch outlet <br />downslope to the natural drainageway. <br />a. The diversion ditches adjacent to the collection pond have <br />' upland drainage areas of 23.5 and 17.9 acres on the north and <br />south sides of the pond, respectively. An analysis of runoff <br />potential for the 100-yr, 24-hr storm was performed for the <br />t northern diversion ditch. This area represents the worst case <br />with respect to total surface area and overland slope. Results <br />of this analysis are presented as Attachment 13. <br />' The analysis was performed using the computer program WASHED. <br />A peak discharge of 17 cfs can be expected to occur in the <br />northern diversion ditch. <br />