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! • <br />39. The draindown volume of the heap leach pad was estimated to be 10 gallons <br />per ton of ore (approximately 20 cubic ft. or .74 cubic yds.). Appendix <br />G, Heap Leach Water Balance indicates that although only 700,000 tons of <br />ore will be processed at any one time, the heap leach pad is planned to <br />contain up to 6.5 million tons of ore. Therefore, the volume of the <br />total draindown of the maximum amount of contained ore should be <br />6.5 million tons x 10 gallons per ton = 65 million gallons. Please <br />clarify. <br />40. The solution containment ponds should include spillway structures <br />allowing for controlled release of solutions, rather than pos~:ible <br />embankment erosion and resulting failure, in the event that a storm which <br />exceeds the design event occurs. Please provide design specifications, <br />including embankment erosion control measures and locations of spillway <br />structures. <br />41. Considering that no emergency pond has been provided in the dE•sign, and <br />that the pond will be constructed as embanked structures with 20-foot <br />depth, further documentation on pond stability should be submitted. No <br />technical specifications on pond construction are provided in <br />Appendix N. Materials, construction techniques, compaction <br />specifications and compaction testing anticipated for use in Fond <br />construction should be documented. Please provide all documentation used <br />to support the conclusion for the pond embankment stability analysis. <br />42. Please specify pond sediment accumulation monitoring, maintenance and <br />disposal measures. <br />Section D.7.4.3 Leak Detection System <br />43. Please specify the leak detection monitoring schedule, reporting <br />procedures, and mitigation methods to be employed, should solution be <br />detected. <br />Section D.8 Project Water Balance <br />Section D.8.2 Heap Leach Facility <br />44. The narrative explains the draindown from deactivated areas has been <br />estimated at 10 gallons per ton of ore with the remainder of solution <br />being held by capillary forces at the estimated field capacity of 12 <br />percent moisture content. Please discuss whether laboratory measurements <br />were taken to verify either the 10 gallon per ton draindown or the <br />remaining 12 percent remaining moisture content of the ore sized <br />material. If not, please consider doing so such that water balance and <br />pond size design specifications can be verified. <br />45. In the water balance model output, a draindown of 2 acre-feet from the <br />deactivated part of the heap is shown. What pad area, ore volume and <br />desaturation rate corresponds to this draindown volume? <br />-7- <br />