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-7- Homestake and its consultants have determined that the 10-day leach period should produce concentrations of leachates representative of the higher concentrations generally found toward the end of stage 2 (rapid increase) of the leachate concentration pattern. It is also believed that the 100 minute period is represented by this stage. The relatively consistent increase that is observed to occur during these time frames enables us to assume a Tinear relationship between the 100 minute and 10-day residence times. Thus one can adjust the leachate concentrations in accordance with time. Of greatest concern in utilizing this linear relationship is that the 10-day residence time would produce lower concentrations than observed in situ, or that the assumption regarding linearity was incorrect and, instead, concentrations at the shorter time interval would be disproportionately high. We are not aware of data showing non-linearity in this time period. Further, since the projected concentrations are so low, namely on the order of 10-6 mg/ml in the pile and 10-10 mg/1 in the stream, the small errors that should be involved could not result in measurable increases. Compensating against the effect of approximati fact that the calculations do not take into account or physical and chemical interactions that occur to leachate ions relative to the movement of the water account for diffusion through physical and chemical to occur should the leachate enter the fill beneath m s in this analysis is the diffusion of the water mass delay the movement of the itself. Nor do they interactions anticipated the low-grade pile. We believe the projected concentrations are conservative in that they are higher than concentrations than would be expected in the field. Again, we note that the projected concentrations are extremely low. Therefore, increases due to increased residence times or other factors would not result in detectable increases in the drainages. In essence, the reclaimed situation will not be unlike the premine situation, except that the higher grade ore has been removed. Item: Abetter discussion on the methodologies and solvent used in the laboratory leachate analysis should be provided. Response: The following methodologies were used to determine the constituents of the leachate samples: Constituent Analysis Deduction Limit Ra-226 Separation Counter 0.1 pCi/1 Uranium Fluorimetric 0.0005 mg/1 Arsenic furnace Atomic Absorption 0.002 mg/1 Barium ICP Emission Spectroscopy 0.005 mg/1 Cadmium ICP Emission Spectroscopy 0.0002 mg/1 Molybdenum ICP Emission Spectroscopy 0.005 mg/1 Lead ICP Emission Spectroscopy 0.025 mg/1 Selenium Furnace Atomic Absorption 0.002 mg/1 Vanadium ICP Emission Spectroscopy 0.002 mg/1 Zinc ICP Emission Spectroscopy 0.004 mg/1 The leachate was formed by immersing the pile of material in rain water collected at the mine site, under simulated flow conditions.