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<br />• <br />Memo to Larry Oehler 7 October 24, 1993 <br />3. Relatively benign material discharged to the impoundment. The <br />operator committed to detoxify the tailings to a low level of <br />cyanide prior to routing them to the impoundment. <br />4. Large depth to water table. The operator made the point that <br />if there were unexpectedly high rates of seepage from the <br />impoundment, it was unlikely that the contaminant plume would <br />ever reach the water table. <br />It was the redundant nature of the facility that assured minimal or <br />zero environmental impact. Item 3 in the foregoing list has been <br />eliminated, in that the AVR system failed, and a high cyanide <br />slurry was discharged to the impoundment. It now appears that item <br />2, minimization of head on the liner, will also be less effective <br />than if a high permeability material were to be utilized as called <br />for in the design documents. The Division can, and should, require <br />the operator to instal a high permeability material for Phase II <br />liner cover. <br />The operator has stated that "the liner cover (drainage blanket) <br />material has been placed by the earthwork contractor, ffiut has not <br />been accepted by (the) engineer and material test work is ongoing. <br />If this material is unacceptable, it will be blended until <br />acceptable or removed". To me, it is implausible that this <br />material would be placed on the critical and sensitive geomembrane <br />without first being accepted by the engineer and BMRI. If a <br />significant amount of out of specification material is identified <br />by the sampling program that has been initiated for the installed <br />liner cover, an enforcement action may be indicated. <br />cc: Jim Pendleton <br />Bruce Humphries <br />Jim Stevens <br />Jim Dillie <br />