2016-07-28_REVISION - M1980244 (2)

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5 —Summary and Conclusions • Page 34: The text states"the dewatering by the drainage tunnels has created widespread dry conditions in at least the upper 750 feet of the diatreme and the adjacent granites in portions of Grassy Valley." However, it was mentioned previously in the evaluation that the diatreme water table is located approximately 1,000-3,000 feet below the ground surface throughout most of the diatreme. In which portion(s)of the diatreme is the water table at 750 feet below surface? RESPONSE:See Hydrogeochemistry Report, Plate 11,for contoured depths to water. The specific answer to the question is along a zone in the Eastern Volcanic Overflow Apron. The comment in the text refers to the eruptive centers, and the areas where there has been underground mining, which do not in general include the apron, which has little gold mineralization. Table 2-1 Water Quality Monitoring Parameters • This Table provides a list of the water quality monitoring parameters that are used at least at all compliance sites according to this evaluation. Please also provide a list showing the established numeric protection levels that are used for all compliance monitoring sites(surface and groundwater). The Division understands that different values may be used for each drainage according to its classification; however,this information should be compiled here in AM-11. RESPONSE:Numeric protection levels for groundwater are provided in the table below for each of the drainages where compliance monitoring is required. Manganese, Sulfate, Dissolved Zinc, Weak Acid Total(mg/I (mg/I as Dissolved Dissociable Drainage as SO4) pH Mn) (mg/I as Zn) Cyanide,mg/I Aregua 1070 6 through 9 8.1 2 0.2 Grassy Valley 250 6.5 through 8.5 4 6.5 Vindicator 800 6.5 through 8.5 2 WCMW 3 250 6 through 9 0.5 2 0.2 WCMW 6 250 6.5 through 8.5 0.2 2 0.2 Figure 2-1 Surface Water and Groundwater Monitoring Locations • As mentioned previously, this figure does not appear to show all of the compliance monitoring sites mentioned in the text(9 surface water sites, 17 groundwater sites). Please revise this figure to include locations of all compliance sites. RESPONSE: Comment noted. A revised Figure 2-1, 2-la and 2-1 b are provided as Attachment 2. • Several non-compliance monitoring sites were also discussed in the text(and data provided in Figures 3-1 —3-6 and 4-1 —4-22); however,their locations are not shown on Page 23 of 28