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Cresson Project – AM-11 Adequacy Review No. 2 <br />Page 2 <br />October 19, 2016 <br /> <br />Please provide a cross-section oriented roughly perpendicular to the southern portion of <br />the ECOSA (at the location of GVMW-8A and GVMW-8B monitoring wells), <br />displaying the ECOSA, the Grassy Valley perched aquifer, Grassy Valley Creek, the <br />groundwater monitoring wells listed above, and the areas identified on Plate 9 (Rev. 1) <br />as “post-mining Grassy Valley capture zone” and “area where drainage tunnels do not <br />cause significant head change in diatreme”. <br /> <br /> Please also provide a cross-section oriented roughly perpendicular to the cross-sections <br />requested above, showing the same features (as applicable). This cross-section should <br />particularly display the nature of the Grassy Valley perched aquifer, and does not <br />necessarily need to be located beneath the ECOSA footprint. <br /> <br /> Please ensure all cross-sections show shallow bedrock groundwater, groundwater flow <br />direction, and indicate the saturated zone (either visually or in notes provided on the <br />cross-section). These cross-sections should provide a unifying picture of the <br />hydrogeology of the area specified, showing the relationships between the ECOSA, the <br />ECOSA underdrains, Grassy Valley Creek, the contact between the diatreme and <br />Precambrian rocks, and the additional features shown on Plate 9 (Rev. 1) and Plate 17 <br />(Rev. 1), with the local groundwater regime. <br /> <br />3.6.6 Impact of East Cresson Overburden Storage Area on the Hydrology of Grassy Valley <br />13) The Operator’s response indicates the ECOSA underdrain system is functioning properly <br />to route infiltration from disturbed areas located outside of the diatreme, to the diatreme. <br />The Operator’s response also indicates the ECOSA underdrain system is designed to <br />conduct water which will seep through areas underlain by Precambrian rock to areas <br />underlain by diatremal rock. Pursuant to Rule 3.1.5(11), no unauthorized release of <br />pollutants to groundwater shall occur from any materials mined, handled, or disposed of <br />within the permit area. The purpose of the ECOSA underdrain system is to direct <br />potentially impacted water (infiltrating ECOSA materials) to the diatreme. Therefore, <br />please specify the maximum flow rate of the ECOSA underdrain system (based on the <br />as-constructed survey), and the maximum infiltration rate and volume of areas drained <br />by the system. <br /> <br />Appendix 2 – Hydrologic Evaluation, CC&V / December 2015 <br /> <br />26-62) Please be informed the Division’s approval of Revision No. AM-11 would not constitute <br />permanent approval of the compliance monitoring stations presented in the application. <br />Pursuant to Rule 3.1.7(6)(b)(ii)(B), the Division may require modification for points of <br />compliance. <br /> <br />Table 2-1 Water Quality Monitoring Parameters <br /> <br />59) The Operator’s response to this item proposed groundwater numeric protection levels <br />(NPLs) for five parameters (Total Sulfate, pH, Dissolved Manganese, Dissolved Zinc,