2008-09-17_REVISION - M1980244 (28)

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• the solution begins to report to the PSSA, the high dynamic inventory can lead to unacceptable (elevated) solution levels in the PSSA. This potential issue can be avoided by utilizing a dynamic water balance. A dynamic water balance tracks the dynamic inventory in the heap and provides an important tool for solution management. By tracking the dynamic inventory, the operator would be able to avoid over- application of solution and control the solution levels in the PSSA. As discussed in Section 10.3 and 10.3.7 of the Project Description submitted within the MLE Project Application, CC&V does not propose changes to existing VLF monitoring requirements or monitoring response requirements as approved under Amendment No. 8. Current approved monitoring and monitoring response requirements for Phases I-IV of the VLF would not change as a result of the implementation of the "dynamic" water balance. Comparable monitoring and monitoring response requirements are proposed in the MLE Project Application for proposed Phase 5. Z. Most of the drainage plan for the storm water hydrology was approved under Amendment # 8. The criterion used to evaluate the AM-09 area is the same as was approved in Amendment # 8. The only exception was a higher curve number used for the East Cresson overburden storage area due to the proposed engineered design with low infiltration cover. The Division agrees with the higher curve number. The Division also agrees with the use of • the two 10 year 24 hour events to design the storm water BMP ponds. CC&V plans to enhance some of these ponds and leave some of them in place post mining as stock ponds. Prior to the Division, allowing these ponds to remain in place post mining, CC&V will have to contact the State Engineer's Office to make sure loss due to evaporation from these ponds is applied for by the land owner (CC&V) in their water substitute supply plan. It would assist the public and any reviewer if the sub watershed delineation maps were at a scale of 1 inch to 800 feet. The sub water delineation maps as submitted are very hard to follow even for those people who are familiar with the project. Please provide a sub-watershed delineation map as requested. Response. CC&V currently accounts for evaporation from the storm water management ponds as part of the augmentation plan for the Cresson Project. CC&V's current practice is to promote the infiltration of storm water collected within the storm water management ponds and thus eliminate evaporative losses. The volume of these ponds would be included in that calculation and reporting as may be required under a revised water augmentation plan for the project, taking into account the MLE Project. These criteria would also be implemented as construction of any neu) storm water management ponds that would be constructed upon implementation of the MLE Project. A legend to be incorporated as part of the sub-watershed delimitation maps is included as Attachment 11 and should assist in interpretation of the drawings included as part of the • MLE Project Application. VII) Exhibit H- Wildlife Information-Rule 6.4.8 45