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Review of Abatement ,~8 Response August 4, 1993 Page 3 BMG should explain why the augering methodology was em~loyed rather than some other more practical one that could have provided some assurance of retrieving saturated sediments from the dgeper depths. I think it is unacceptable to eliminate the need or adequate sampling because of difficulties encountered using he sampling methodology. Included in the explanation should be a iecuesion of the mineralogy of the ore body indicating that tailings in the upper few feet of the tailings pile have the same or similar ineralogy ae those in the deeper depths. In view of the re irements of Abatement 8 that the liquid portions of the tailings b sampled and analyzed, BMG should furnish some indication of why t ie issue has not been properly addressed; that ie, why only one samp a of liquids was collected. HMG should also explain why they f el that one sample of fluid "should represent the pore water t depth in tailings deposited with high cyanide concentrations" ( .34). Given the time it takes to collect and analyze the tailings samples, and assuming further sampling will be necessary, HMG ehou d adopt and initiate a sampling methodology that will provide reeu to quickly. APPENDIX Leach tests. A. The accelerated weathering test employed to eimula a weathering of the Battle Mountain Tailings, both in the original ermit and in the response to Abatement item #`8, seems not to accou t as well ae possible for the conditions that will exist at the ei e. Although I believe it is appropriate to use simulated rain ater as the leachate, I believe also that the acids produced as a p oduct of the first weathering cycle should be recycled back into th, tailings ae other rainwater is added. ' BMRI should explain why the EPA Method 1312 was choeen,and describe more fully why this method was chosen over other accelerated weathering testa that are available. BMRI should also describe the results of the accelerat d weathering test in terms of the Battle Mountain tailings syet What is likely to happen to the leachatee under the phyei graphic and climatic conditions at the Bite once the system is cl eed? B. Some of the weathered tailings samples have metal concentrations which are at or near the levels for surface water et~andards for, say, the Rio Grande River. BMRI should explain the high metal concentrations in arms of the site conditions that will exist upon closure. The D'vieion needs certain assurance that, under the present reclamation lan, surface water that leaves the site will not be degraded by weathering of the tailings.