Laserfiche WebLink
• Response: <br />CC&V agrees that the precipitated gypsum from the neutralization process will not react <br />with acids. The point about the gypsum precipitation is that it replaces the dissolved <br />carbonate, and plugs the conduit along which the acid was being transported. This forces any <br />remaining acidic fluids to find another pathway. In doing this, it would be obliged to contact <br />un-reacted carbonate. <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 />Response: <br />The attenuation properties of the rock material in the Cripple Creek diatreme have been <br />evaluated by performance of humidity cell tests with large amounts of neutralizing materials. <br />There is little attenuation in rock that has previously been acidified. Also, the resulting <br />concentration after neutralization of acid HCT leachate is approximately the same when <br />neutralization is done with liquids and solids. This indicates that the presence of the solids, <br />upon which adsorption would take place if it 71yere favored, is not a significant factor in metal <br />• removal. <br />No credit has been taken for attenuation in the evaluation. <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- base property of the rock. <br />Response. <br />CC&V predicts a flow through the ECOSA of 23 gpm. No range is given for this flow, <br />because it turns out to be irrelevant to the mass flux evaluation. The mass of oxidation <br />products transported into the diatreme for neutralization is not dependent on the flow rate, <br />but is dependent on the rate of oxidation, which has been quantified. Accordingly, CC&V has <br />not specifically quantified the flow through the remainder of the individual facilities. <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/ 1, 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 />Response. <br />41