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The Leadville Mill 4.4 ORE STOCKPILES M1990-057 EXHIBIT C — MILL PLAN Page 4 -19 Existing ore stockpiles have been stored on site since 1991. The stockpiles, until they are reprocessed or disposed in the TSF, will be maintained in the following manner to mitigate the potential in generating acid rock drainage (ARD). The following measures will be implemented to mitigate potential surface or groundwater contamination impacts: • Existing stockpile ore considered to be acid or toxic producing materials will be covered with reinforced visqueen or alternative impermeable material; • Reinforced visqueen sheeting, approximately 40ft x 100ft sheets, will be placed over the piles, edges folded and pinned, and held in place by tires, blocks, rocks and /or other suitable ballast; • The water runoff from the reinforced visqueen will be passed through a combination of erosion and sediment control measures including natural minor depressions, constructed berms, silt fence and vegetative filters; • Reinforced visqueen will be maintained and replaced as needed; • Stockpiled ore will be sampled and a TCLP analysis will be performed, as outlined in the Division's August 27, 2009 letter prior to removal and prior to milling or disposal; • Provide CDRMS an ore stockpile removal schedule; and • Weather permitting, historical stockpiled ore will be removed and disposed in the TSF within 60 days after the permit has been approved; 4.5 MILL UTILITIES & SERVICES 4.5.1 ELECTRICAL POWER The mill receives electric power from XCEL Energy. The connected load is about 130kW. The power is delivered by a 38kV overhead line across the northern portion of the property, connecting to the northeast corner of the Mill Building. A portable generator will be available on site for emergency conditions. Version 1.0 April 2013