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June 8, 1990 Page 5 through 18 inch galvanized culvert to the clean c 11 of the impoundment. The Division interprets this stateme t to mean that an 18 inch galvanized culvert will be construct d all the way from the point of diversion at Columbia Ditch to the clean cell of the impoundment. if this interpretation i correct, please verify. if it is not, please provide all i formation requested. In the attached report RRI has provided a descripti n of the diversion that will be employed to carry raw water into the impoundment. This approach to diversion has been used hi torically without incident. As a no-discharge operation the Alma Placer Mine is not object to the NPDES categorical standards for the Gold P1 cer Mine Subcategory found at 40 CFR 440.140. Regardless, tha body of regulations provides specific performance standards for erns, but does not specify performance standards for diversion s ructures. The regulations do provide that the diversions must be ffective, must protect from sudden and catastrophic failure, an must be maintained. (See 40 CFR 440. 148(e)). RRI asserts that the existing diversion system satisfies those requirements. EXHIBIT L - RECLAMATION COSTS Our May 21, 1990 correspondence indicates that a $40,600.00 will be necessary. Please provide estimate, or concurrence with our recommendation. See comments immediately below. EXHIBIT L - RECLAMATION Cost Estimate Doze tails from 1.5 day operation No comment. Push embankment of pond 1 to 48 slope Phase I Sond of a re ised cost $ ,889.05 $ 1 ,208.00 RRI's concurrence with this figure is dependent on he MLRD's response to our comment on finished grading, immediatel below, Finish grade 27 ac @ $555.54/ac $ 11,999.58 RRI asserts that the costs to push the embankment of po d 1 to 48 are duplicated in the finish grading, and the grading costs are unreasonably high given the pre-disturbed nature of the mine site and the historical post-mine site performance standard p oposed for