2000-01-31_REVISION - M1988112 - Laserfiche WebLink

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.~ SHEPHERD MILLER, INC. Environmental and Engineering Consultants TECHNICAL MEMORANDUM DATE: January 3l, ?000 TO: Battle Mountain Resources, [nc. FROM: Jim B. Finley SUBJECT: Revised West Pit Pore Volume Calculations Introduction Sufficient additional hydrologic and geochentical data have been collected from groundwater monitoring wells in the vicinity of the West Pit to warrant revisiting the initial ca culation of the volume of water required to flush secondary sulfate salts from the backfill material. Review of Basis for the TR-26 Calculation The estimation oY' pore volumes required to flush secondary sulfate salts from the hacktilled West Pit as presented in TR-26 was taken from the analysis presented in Appendix P. of the TR-l~ Response Plan (hereafrer "Response Plan°). The geochemical analysis conducted as part of the Response Plan was based on a combination of experimental data (from batch leaching tests) and initial concentration data obtained from the backfill groundwater monitoring well 13F-2. When batch leach laboratory tests were completed using materials representative of the backtill material placed in the West and Pinl: Gneiss Pits. Results of the all oY the laboratory tests conducted on solids materials present at the San Luis Mine were presented in Appendix A of [he TR-1 ~ Response Plan and in Appendix B of TR-26. The batch leaching tests were developed specifically to address the potential for the backtill materials to produce dissolved salts upon flushing by natural groundwater inflow to the backfilled West Pit. Sulfate was chosen as the indicator parameter because secondary sulfate salts were the most likely salts to form in response to the oxidation of sulfide minerals in the Precambrian bedrock. 3801 Autonudion W"ay, .Suite /00. Fa"t Collins, Colorado 80.i2~ Telephone (970) 2?3-9600 / F;1.1 (9i0) ?23-71 ?I