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<br />LOCAL HYDROLOGY <br />In the vicinity of Battle Mountain Gold's San Luis mine, and in the San Luis Valley farther <br />west, Rito Seco Creek is a losing stream, at the present time. That is, water flows from the stream <br />bed into the alluvium, rather than from the alluvium to the stream. <br />As the groundwater level within the pit equilibrates with the adjacent undiswrbed ground, the <br />pit should fill to some level similar to past levels. At that point, the valley fill alluvium and water in <br />the West Pit should re-establish a gradient toward the stream, and the stream should once again <br />become a gaining stream in the reach near the mine. <br />Once established, the water table is likely to fluctuate in response to seasonal and yearly <br />variations in surface precipitation. Rock within the permanently-saturated zone Should be the most <br />stable and should weather at an extremely !ow rate. Rock above the water table will weather in <br />response to the periodic passage of rain and snow melt enroute to the groundwater table. Rock within <br />the zone of fluctuation will be subject to the most intense weathering, due to alternate wetting and <br />oxidation. <br />DUMP CONFIGURATION <br />The West Pit waste rock dump is to contain rock from two units: the Prectimbrian pink gneiss <br />and the Tertiary Santa Fe formation (Figure 1). The upper part of the dump will contain rock that <br />is currently stored in Waste Dump B and pink. (Waste Dump B contains rock from the South Pit, <br />which is mostly from the Santa Fe formation; a lesser quantity of Pink Gneiss exists in this dump.) <br />The lower part of the West Pit will contain the Pink Gneiss. <br />Groundwater will fluctuate mostly within dump material comprising the Santa Fe formation and <br />lower Waste Dump B. The Pink Gneiss will be placed mostly below what should be the eventual <br />water table. Thus, the Pink Gneiss should be expected to weather at an extrerely low rate. <br />METHODS <br />The BMG reports indicate that the operator collected representative samples, and that <br />appropriate collection and analytical procedures were employed. Single rock type samples were <br />considered representative of the unit as a whole. Chemical analyses are assumed accurate without <br />evaluation of lab QA or QC procedures. <br />The tests cover a range of techniques including: <br />a. Acid-base accounting <br />b. X-ray Fluorescence <br />c. Batch leach testing <br />2 <br />