1990-01-09_REVISION - M1988112 (6)

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90 01105 18:38 S 303 985 9947 9RK DE N'JER 07 ~ ~ BATTLE MOUNTAIN RESOURCES, SAN LUIS PROJECT CMLRD ADEQUACY LETTER RESPONSES Page 21 of 28 EXHIBIT E, RECLAMATION PLAN 39. It 1s apparent that detoxification and/or treatment of the tailings material after deposition will be impossible. Therefore, any necessary treatment of the tailings material must be accomplished prior to deposition. 7n order to determine what, if any, treatment 1s necessary, geochemlcal analysis of the material at the point of deposition must be provided. In order to judge whether treatment is necessary, a criteria for evaluation must 6e established. Our analysis indicates that any seepage or flow from the facility would most likeiy Infiltrate into the co11uv1a1 material a short distance from the dispesal facility. Therefore, the adopted groundwater standards are applicable to the effluent from the facility. Battle Mountain must demonstrate that Impacts to the hydrologfc balance are minimized after ,reclamation is Complete. A predictive model of the effluent, given post reclamation conditions and the geochemica] characteristics of the tailings, should be submitted. If the model suggests treatment of the tailings prior to deposition is necessary, a pion to do so should also be submitted. RESPONSE: Geochemicat analyses of the discharge slurry are given in Attachment 1 and described in Response No. 2. During operation, flows from the facilities drainage network will be routed to the collection pond. Both quantity and quality of this solution will be monitored during operation. As the tailings facility is operated the rate of drainage will decrease as the tailings ad,~acent to the drainage network consolidate, reduce in permeability, and drain. At the end of operation, the flow rate is predicted to have decreased to approximately 10 gpm and will continue to decrease following cessation of operation. This prediction is b$sed upon permeability of the tailings reading approximately 10- cm/sec. Drainage will also be controlled by the degree of saturation of the tailings ad,~acent to the drain layer. The proposed reclamation will involve a period of in excess two years during which time reclamation of the surface of the tailings facility will be performed. The collection pond will be maintained dur{ng this phase. Decommissioning of the collection pond is anticipated to be possible at the end of this period as solution flows reduce to nondetectable levels. In the event flow rates do not decrease at the predicted level BMR will maintain the facility until such rates are achieved.