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better knowledge of the factors controlling alkalinity generation could greatly help in the <br />future mitigation. <br />0. The reported carbonate contents of the diaterme below elevation of 7500-8000, based on <br />data from only three deep drill holes, is substantially greater than the reported carbonate <br />content of shallower depths that were based on a significantly larger number of drill holes. <br />Is the carbonate content at depth real, or is it a function of the smaller sample size and good <br />fortune in hitting carbonate rich zones when drilling the deep test holes? It would be <br />beneficial to have more complete deep drill hole coverage. Lacking that, DRMS <br />recommends sensitivity analyses of the acid-generating characteristics of the deep diateeme <br />assuming a more uniform carbonate content top to bottom. <br />P. The DRMS is concerned that the three deep drill holes do not provide adequate spatial <br />sampling representation. Please provide a map showing the locations of the three deep drill <br />holes used for carbonate characterization. <br />Q. Lacking the quantity of data for deep lithology, it would be prudent to continue to update <br />and calibrate the environmental model with ABA analyses of blast hole or mine face sample <br />as mining progresses. <br />R. Applicant states that dissolution of carbonate minerals creating enlarged preferential <br />pathways is not a concern because the carbonate would give way to gypsum and maintain <br />the integrity of the pathway. This may be correct from a physical hydrologic standpoint, <br />but this scenario would result in a progressive depletion of carbonate in favor of the non- <br />neutralizing minerals gypsum or anhydrite. Thus, infiltration through those pathways <br />might eventually encounter progressively less carbonate as time goes. One mitigating <br />circumstance surrounding this concern is the fact that the Carlton Tunnel discharge <br />alkalinity has been increasing again of late. <br />S. In the event of leachate release to the environment, it is always useful to have some <br />knowledge of the expected geochemical interaction between the leachate and material <br />underlying the pile, bedrock or unconsolidated material, to assess the attenuation <br />properties of the material. This can also be done using leach test, but might be better <br />approximated using sequential batch tests, which is a documented ASTM method. <br />T. For post closure, CC&V should provide a worst case scenario of the quantity and quality of <br />release from the overburden storage areas. CC&V predicts a long term average release of <br />6.8gpm, but ranges would be useful. And again for water quality CC&V stresses the bulk <br />acid- ase property of the rock. <br />U. The prediction that the overall seepage water quality will be similar to the Carlton Tunnel <br />water is not entirely gratifying, since the Carlton Tunnel has sulfate running over 1,000 <br />mg/l, which is 4x the drinking water standard. The DRMS is well aware that the Carlton <br />Tunnel discharge is covered under the NPDES, discharge under the Colorado Water <br />Control Division and that the sulfate amount was about the same prior to Anglo's operation <br />in 1994. However, the DRMS has a responsibility to control the source of sulfate loading <br />from areas approved under our permitting process. <br />a) DRMS had been observing peaks and valleys and a steady gradual increases in <br />sulfate concentrations in GW monitoring compliance wells in Arequa Gulch. <br />12