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• treatment system. Environmental protection measures for the treatment facilities are described in detail <br />in Exhibit T and Appendix H. A description of the treatment components follow. <br />Untreated Water Tank <br />Three-inch diameter high density polyethylene (HDPE) pipe extends from the mine sump to the <br />Untreated Water Tank. A 2-inch return line extends from the tank back to the mine. These water lines <br />are buried from the portal to the tank to prevent freezing. A third, 6-inch diameter HDPE buried pipe <br />will be installed from the ore pad sump to the Untreated Water Tank when the ore pad is constructed. <br />The Untreated Water Tank has dimensions of 68 feet by 68 feet by 4.75 feet high and is constructed of <br />interlocking metal wall panels. The tank is lined with two 30-mil, reinforced synthetic liners. Leak <br />detection is provided by an 8-oz. geotextile fabric that is located between the two liners and connected <br />to a dip tube leak detector. Tertiary containment is provided by a GCL liner that is installed at the base <br />of the tank between the wall panels. The tank has approximately 22,000 cubic feet of storage capacity <br />. (equivalent to 164,000 gallons of untreated water). Freeboard requirements are described in Section 18 <br />below. <br />Water Treatment Plant <br />The treatment plant is mounted in a 47-foot-long truck trailer. There are three mix tanks of 370, 300, <br />and 230 gallons containing dilute solutions of barium chloride, ferric sulfate, and other chemicals as <br />needed (See Exhibit T and Appendix H). These chemicals are fed into the untreated waterline via <br />metering pumps. After chemical dosing, the water flows through in-line static mixers to two 335- <br />gallon reaction tanks. These reaction tanks are equipped with mixers that provide additional contact <br />time between the treatment chemicals and the natural contaminants in the water (i.e., radionuclides, <br />selenium and other trace metals). The water then flows by gravity into a Settling Tank located outside <br />the trailer. <br />• <br />Whirlwind Mine 07 (rev. April 08) D-16 <br />