2012-02-28_REVISION - M1980244 (104)

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Table 14 -2 Potentially Toxic Chemicals In Use at the VLFs, ADRs, and High Grade Mill Chemical Name Use at the Site Location for Use Location for Storage Typical Quantities Used and /or Stored on Site Secondary Containment Provided Fate of Chemical Sodium Cyanide Delivered to the site in dry bulk and mixed adjacent to ADRs and High Grade Mill facilities. Used as a dilute solution for leaching and product recovery. VLFs, ADRs, and High Grade Mill facilities The sodium cyanide is or will be delivered as briquettes to the ADRs and the High Grade Mill facilities. The tanker containing the briquettes parks within a containment surface, and the briquettes are dissolved in water and pumped to holding tanks. There are two holding tanks for sodium cyanide at the AGADR, two holding tanks will be at the SGADR, and one holding tank will be at the High Grade Mill facilities. Each holding tank is 20,000 gallons in size. At least one 7,500 gallon tanker is on site to be staged and mixed at each facility The dissolving of the briquettes occurs within secondary containment at the ADRs and High Grade Mill facilities. The holding tanks are also located within secondary containment on concrete foundations with curbing. The SGADR, AGADR, and High Grade Mill facilities are underlain by a geomembrane liner system for tertiary containment. Is consumed in the dilute sodium cyanide solution leach circuit — see next box for ultimate fate of sodium cyanide process solutions. Dilute Sodium Cyanide Solution Barren solution is piped from storage locations to the VLFs and pregnant solution is piped from VLFs to ADRs. Dilute sodium cyanide solution is used in the High Grade Mill facilities to bring the gold into solution from both the ground product and the carbon. VLFs, ADRs and High Grade Mill facilities ADRs, cyanidation, and CIP tanks in High Grade Mill and in PSSAs within the VLFs. At each of the ADRs: - Internal barren tank of 20,000 gallons - Strip pregnant tank of 20,000 gallons - Strip barren tank of 20,000 gallons - Two Strip intermediate tanks of 20,000 gallons each - Two barren enrichment tanks of 80,000 gallons each at AGVLF only 29,100 gpm being applied at AGVLF at a strength of less than 250 mg/L sodium cyanide. 17,000 gpm to be applied at SGVLF at a strength of less than 250 mg/L sodium cyanide. Solutions are continuously re- circulated between the VLFs and ADRs. At the High Grade Mill facilities: - 20,000 gallons mixing tank 211 gpm(77 tons of slurry per hour) being continuously circulated within the High Grade Mill facilities at a strength of 2,500 mg/L sodium cyanide Dilute sodium cyanide solutions have primary, secondary, and tertiary containment at the VLFs, ADRs, and High Grade Mill facilities. Piping is within secondary containment or double - walled when outside of containment. See Sections 6.0, 7.0 and 8.0 of Project Description for complete details of the containment. The VLFs will be rinsed as will any tanks and lines that have contained sodium cyanide process solutions. Dilute sodium cyanide solutions are expected to breakdown during rinsing. Upon completion of rinsing, the dilute solutions will be treated with hydrogen peroxide or circulation enhanced to allow evaporation of water. Sodium Hydroxide Used for pH control VLFs and ADRs Stored in liquid form at ADRs 20,000 gallon tanks at each ADR Tanks are within concrete containment and also located on the lined area of the VLFs. Concrete containment is equipped with a float - activated pump that would return fluid to the plant in the event of release. Outside of concrete containment releases would flow onto VLF liner systems. Is consumed in pH control for process solutions. Hydrochloric Acid Used to acid wash carbon in carbon columns in the ADRs. ADRs Stored in mixing tanks at ADRs. Stored inside ADRs in holding At each of the ADRs: - 8,200 gallons stored in mixing tank - 7,000 gallons in holding tank Mixing tanks are double walled and within concrete containment outside of ADRs. Acidic solutions that have become neutralized through rinsing of the carbon and are not longer useable, Cripple Creek & Victor Gold Mining Company Cresson Project Mine Life Extension 2 14 -4