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<br />13 <br />In a similar replo to data for paste pH and the latest data in the report on humidity cell <br />effluent pH, in Figure 2, we can see again that the waters contacting finely divided <br />samples (paste pH) and those contacting coarser material (humidity cell samples) are <br />markedly different in pH. Specifically, in all cases, the paste pH yields waters with higher <br />pH levels than the waters from the humidity cells. <br />This again suggests that the capacity of the Cresson materials to neutralize acid <br />waters is a function of the availability of the basic minerals and this availability is <br />improved by finer grinding. It is also interesting to note that in none oC the cases <br />shown is there evidence that the finer grind has preferentially increased acid <br />generating minerals exposure to the extent that any net higher levels of acid <br />production accompany the finer grinding. <br />Based upon my understanding of the plans for handling of the Cresson overburden <br />material, I expect that the material proposed for deposition in the Ironclad, Globe Hill, and <br />Cresson Pits, as well as the lower sulfide material to be placed in Arequa Gulch, will be <br />relatively coarse material. The comparison of paste pH data, net neutralization <br />potential data, and humidity cell test data suggests that this coarse material may in <br />fact present the highest risk of developing acid and metals mobilizing drainage and <br />that, if technically and economically feasible, some crushing or grinding of the <br />materials prior to deposition might reduce this risk <br />OMLR951 DEH <br />