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Battle Mountain Resources <br />November 1, 2000 <br />Page 7 <br />The unsaturated pore volume was re-calculated using the surface area of the West I''it (27 I acres) <br />and an average depth to groundwater of 25 feet (groundwater table elevation of approximately <br />8579 feet amsl). Based on this information, and the estimate of the specific yield reported <br />previously, the unsaturated pore volume in the West Pit under current conditions is 6,810,483 ft'. <br />Therefore, the total saturated pore volume in the West Pit is the difference between the total pore <br />volume (18,335,917 ft') and the unsaturated pore volume (b,81Q483 ft3), or 1,,525,433 ft'. <br />Thus, one pore volume in the West Pit corresponds to 88,587,877 gallons of grcundwater at a <br />groundwater table elevation lower than 8582 feet amsl. g3, 731, 0 6:z ~4 <br />For purposes of evaluating the current status of the West Pit backfill groundwater system witft <br />regard to flushing pore volume requirements, the amount of groundwater that has been extracted <br />from the West Pit backfill needed to be converted to number of saturated pore volumes. The total <br />volume of groundwater extracted from the West Pit corresponds to the sum of the cumulative <br />volumes of groundwater pumped from BF-3, BF-4 and BF-5, which are the three West Pit <br />backfill groundwater wells used to maintain the groundwater table elevation in tie West Pit <br />Table 1 shows a summary of the West Pit backfill pumping volumes and the equivalznt number of <br />pore volumes pumped in each month. <br />3.2 Measured Backtill Geochemistry <br />Subsequent to the development of the TR-26 water management plan, extensive additional <br />hydrologic and geocltemical data have been generated as a consequence ot~ the TR-26 <br />performance monitoring program. These data reFlect the specific field conditions that affect <br />secondary sulfate salt flus}ing in the West Pit backfill The field data provide direct empirical <br />evidence regarding the flushing characteristics of the West Pit backfill and have beer evaluated [o <br />refine the backfill flushing requirements. <br />The final TR-26 West Pit backfill groundwater monitoring requirements include monthly sampling <br />at BF-4 and BF-6. Prior to June 2000, BF-2 was sampled in conjunction with BF-~. Therefore, <br />the water quality data collected from BF-2, BF-4, and BF-6 constitute the most complete sets ot~ <br />163(Midpoint Dr., S'r~ile B, Fort Collars, Colorado 80.52.1 <br />Telephone (970) 484-7704 /FAX (970) 484-7789 <br />