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<br />June 16, 1993 <br />Ms. Nora Jacyuez, Esq. <br />Attorney at Law <br />6458 South Quebec Street <br />Building 5 <br />Englewood, Colorado 80111 <br />Dear Nora: <br /> <br />I have looked over the introduction to the Battle Mountain Gold (BMG) res onses to <br />abatement requirements 8 & 10, the text to which the introduction refers to he extent that <br />chemical issues are addressed, and your notes on the document. The followi g comments <br />are based on these items and reflect my opinion relative to the adequacy oft e arguments <br />put forth by BMG that the current permit and bonding requirements are ade, uate. <br />Surrtmarizing the activities discussed in the document and relating to the the ical <br />composition of the tailings at the San Luis facility, I think the following are f• dually <br />accurate and form the basis of conclusions relative to risks presented by the t flings and the <br />needs to address these risks today and in the future when mining and gold re overy cease: <br />1. The original operating plan called for the use of an acidif1ication- <br />volatalization-recovery (AVR) system to permit cyanide recycle and to <br />minimize the cyanide reaching the tailings impoundment. <br />This system proved unworkable, was subsequently abandoned, a d as a <br />consequence more cyanide that had originally been propos~d was <br />discharged to the tailings ponds. <br />2. When the level of cyanide in the tailings pond reached excessiv~ levels <br />(several hundred parts per million) BMG installed the CYTOX sy tem to <br />deal with this problem. <br />The CYTOX chemistry revolved around converting cyanides to insoluble <br />iron and zinc salts which were precipitated in the tailings solids. <br />The precipitation of the CYTOX solids in the tailings ponds restMlted in <br />putting more cyanide and more metals (zinc and iron) in thesQ waste <br />impoundments than was anticipated in the original permit. <br />DEH061693 <br />