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• T <br />~ t <br />information. Further, there are two leaky dams that catch runoff in the ephemeral drainages <br />that border the Ironclad and Globe Hill mines. These are both inspected and are locations <br />where runoff can be collected. To date, there is little, if any runoff from the overburden that <br />reaches these dams. Only local snow melt runoff is observed. <br />Dr. Hyatt appears to be in agreement with the delineation of 0.8% total sulfur as <br />distinguishing between the material with a higher risk of acid generation and metals <br />mobilization (1 1, page 5 of his comments). <br />Dr. Hyatt's analysis confirms both the correlation of sulfide sulfur with visible pyrite as well <br />as total sulfur with visible pyrite, while observing that the lower the visible pyrite, the less <br />precise the correlation may become. <br />Dr. Hyatt observes "This is not to say, however, that the dynamics of water and air <br />contacting the overburden piles will be such that we can expect any discharge from them to <br />be of exactly the same quality as waters which have contacted in-plane materials in the <br />weathering deposit." He goes on to note "This data suggests, that when both acid generating <br />and acid neutralizing minerals are exposed by fine grinding, waters contacting the system <br />will tend to exhibit what amounts to a buffered pH in the range of about 4.3 to 8.8. This is <br />interestingly close to the pH of waters in various parts of the natural environment in the <br />Cripple Creek district and may support the contention that the area has a net buffering <br />capacity to handle acid drainages so long as there is sufficient contact between the acid <br />waters and neutralizing minerals." Obviously, in view of the fact that the native materials <br />are not fine ground and that yet they neutralize the waters removes the emphasis on fine <br />grinding as something that should be employed in full-scale operations. <br />In this context, Dr. Hyatt appears to suggest that CC&V mix the various rock types, as he <br />characterized the sense of CC&V's original plan for overburden disposal. He notes that this <br />mixing concept is probably more speculative than based on data. CC&V is reluctant at this <br />time to change back to and thus plan such mixing unless the OMLR feels that it is an <br />improved approach. Containment of the >_0.8 percent material as backfill to the Ironclad <br />and Globe Hill mines appears to be a better resolution. CC&V reasons that much more <br />buffering capacity exists through the bulk of the caldera into which infiltration into [hat <br />material will drain. <br />Dr. Hyatt re-addresses this theory of finely ground versus coarse material in a number of <br />places. As the OMLR is aware, it would be economically impossible to grind any <br />appreciable overburden in this situation. Effectively, the process would be identical to a <br />milling operation and thus would require, at current product prices, much higher precious <br />mineral concentrations. Just as Dr. Hyatt stated, quite perceptively and accurately, that "any <br />approach [to minimizing the amount of efFluent] will require careful analysis from both a <br />technical and cost standpoint since large amounts of material and capital are likely to be <br />involved in any of these or other choices." He also does not conclude that acid development <br />and/or metals mobilization will occur and that this minimization is absolutely necessary, but <br />4 <br />