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6.4.21(7)(b) <br />There are no Designated Chemicals to be used in this operation. <br />There is no acid mine drainage from any adits, tunnels, or underground mine workings on this site either pre- <br />existing or proposed. <br />6.4.21(7)(c) <br />There will be no changes to the current, natural geological structure of the permitted area. All proposed operations <br />are surface in nature. The geochemical conditions will only improve by removing the acid forming materials <br />(sulfide minerals and heavy metals) by removing the pre-existing waste rock for offsite processing. <br />6.4.21(7)(d) <br />No monitoring stations shall be necessary. The pre-existing waste rock is being removed completely in a relatively <br />short duration of time. <br />6.4.21(7)(e) <br />There are no Designated Chemicals to be used in this operation. <br />To avoid redundancy, the handling methods of potentially acid forming waste rock has been described at length in <br />Exhibit C and above in 6.4.21(6)(a). <br />6.4.21(7)(f) <br />Drainage control within the Affected Area has been considered using the U.S Soil Conservation Service, Technical <br />Release 55: Urban Hydrology, for Srnall Watersheds, USDA (US. Department of Agriculture), June 1986 and the <br />Federal Highway Administration Hydraulic .Engineering Circulars HEC-1 1 & 11F.C-1 S for design guidance. Refer <br />to Exhibit C, 6.3.3(2)(c) for a storm flow analysis. <br />See Stormwater Management Plan attached as an appendix to Exhibit C for best management practices. <br />6.4.21.(8)(a) <br />On a map generated from the CO Division of Water Resources in the appendix of Exhibit C is shown water <br />resources, consisting of surface water and groundwater wells, near the proposed operation. <br />6.4.21(8)(b) <br />There are minimal perched zones or traditionally defined aquifers known in this mountainous area. The site is <br />completely composed of crystalline Precambrian rocks, i.e. gneisses and schists, and tertiary intrusive rocks such as <br />quartz monzonit:es overlain by 0-24" of unconsolidated material. <br />Unconsolidated materials, soils, of between 0 and 18"-24" overlay the crystalline rocks. The rocks themselves have <br />essentially no porosity or permeability. Random, in-identifiable fractures due to jointing and faulting provide the <br />only groundwater transmissivity and relative porosity. The site is underlain by numerous mine openings, the most <br />important of which is the workings of the Old Town Mine (mine complex immediately adjacent to the east). This <br />mine's workings effectively drain the area underneath the site, connecting the Old Town to the Argo Tunnel via the <br />Hot Time Lateral. Refer to a map from USES Professional Paper 359, ECONOMIC GEOLOGY OF THE <br />CENTRAL CITY DISTRICT, GILPIN COUNTY, COLORADO, Sims, P. K.,, Drake, A. A., and Tooker, E. W., <br />1963 at the end of Exhibit C detailing this. <br />Hydraulic conductivity for the undisturbed rock types present at the site, in-situ before mining, ranges from 10-2 - <br />10+2 gallons per day per square foot (as reported by Freeze and Cherry (1979)) due to joints and fractures in the <br />rock. The existence of the underground mine workings provide a direct hydraulic conduit for groundwater beneath <br />the site. <br />As previously stated, the Argo Tunnel is within the vicinity beneath the proposed Affected Area at a depth of <br />approximately 1,500 feet. The Argo Tunnel drainage is monitored, collected, and treated at the Argo Tunnel <br />Treatment Facility located in Idaho Spuings. <br />Page 4 of I I