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included. I No application change necessary. 88. We are concerned that the quantity and duration of post-mining ground water inflows to the west pit may be greater than anticipated. The data presented does not appear adequate to completely substantiate the prediction that the pit will not contain permanent standing water after reclamation. For example, there is insufficient information which shows how the pit will intersect the faults and fractures, such that their influence on the hydrologic system can be ascertained. It is Likely that the horizonta] and vertical extent of fracturing probably goes beyond the economically mineralized zone. Therefore, the lateral extent of this fracture-controlled aquifer may extend beyond the pit area. It is also unclear whether dewatering will cause a hydraulic gradient reversal in the alluvia) aquifer in the vicinity of Rito Seco and thus ' provide an unanticipated source of ground-water flow from the south. In order to resolve this concern, we suggest that Battle Mountain initiate further hydrologic investigations. These investigations should 1 produce a predictive model which describes, given the additional research, the potential for continued post-mining pit inflow from the Rito Seco alluvium and the pre-Cambrian aquifer system. This model 1 should be completed prior to west pit disturbance, as the result may impact the proposed reclamation plan. If post-mining inflows are likely, two potential reclamation plan modifications will need to 6e evaluated. These alternatives are: 1 1. Areas coincident with the anticipated pit water level elevation should be backfilled ar graded to 3H:1V slopes from five feet above water to 10 feet below, as would be required of any post-mining ground water lake; or ' 2. The pit shou]d be backfilled to above the anticipated water 1pve1 with waste rock, topsoiled and revegetated. Response: Based on the data presented in the permit application, BMR does. not believe that there will be significant inflows to the West Pit following completion of mining operations. The studies conducted in the ore zone aquifer as described in Exhibit G indicate that the aquifer is bounded by a fault barrier on the east side and flows from the east do not occur. Based on the green clay/mudstone fault zone which creates the confined ore zone aquifer and the behavior of the fault zone between the East and West Pit areas, there is evidence that faults in the project area act as barriers to flow. In addition, the ore body dips to ' the south and west and flows from the south and west are not expected. Based on the rapid changes in well yields over the period of testing for artesian wells in the West Pit area, the recharge to the system from the north is judged to be limited either as a result of barrier faults or limited recharge area. Since the aquifer system is both fault and fracture controlled, we do not know of a predictive model which would allow an