Eagle Mine Superfund Site Public Tour

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C M. process, as problems with the original remedy were identified, modifications to the plan were implemented. In addition, as a result of studies conducted by EPA, further remedial action was required. In 1995, EPA, the State, and Viacom International, Inc. entered into a Three -Party Consent Decree to implement the additional work. This included development of a biological based water quality clean -up standard for the Eagle River and removal of contaminated soils from the Maloit Park Wetlands. In October 2001, construction of the remedy was declared complete. Ongoing maintenance and monitoring activities continue. WATER TREATMENT Problems with the original remedial action plan became very public when water being pumped back into the mine reached fractures in the bedrock at an elevation around 8500 feet above sea level. Metals contaminated water began to seep out, causing the Eagle River to turn orange. As a result, ski resorts using the river for snowmaking produced orange snow. At that time, the plan to flood the mine workings was abandoned. Instead, a small water treatment plant to treat water from the mine was then installed which was soon upgraded to a full -scale process plant. The water treatment plant continues to be a vital part of the remedy. In addition to treating water from the mine, contaminated groundwater is collected at the Consolidated Tailings Pile through a trench system and pumped to the water treatment plant. The water treatment plant treats around 140 million gallons of water annually (averaging around 350 gallons per minute), and removes approximately 175 pounds of zinc per day. Currently, the water level in the mine pool is at an all -time low level, and may soon be near the elevation of the gravity feed intake at 8450 feet. The water treatment plant is a "lime and settling" type plant. Lime and soda ash are added to the contaminated water to raise the alkalinity (pH) of the water. A chemical, called "polymer" is then added to promote the settling of the solid particles containing metals. The solids are settled out in a clarifier. Sludge is removed from the bottom of the clarifier and pumped to sludge presses that squeeze out the water. Dried sludge is disposed of in a lined, on -site holding area. Acid is added to the treated water to reduce the alkalinity of the water to acceptable discharge limits. The treated water is then discharged to the Eagle River under the provisions of a discharge permit issued by the state's Water Quality Control Division of CDPHE. Averaae Influent and Effluent Qualitv of Eaale Mine Water Treatment Plant for 2003 Parameter* Water Flowing Water After Treatment Concentration Required Into the Plant By i:he Plant To Be Met by State of CO On Monthly Basis Cadmium - Total 0.08 Not detected .a 0.05 Copper - Potentially Dissolved 0.095 Not detected 0.012 Iron - Dissolved 6.172 0.04 0.3 Iron - Total Recoverable 27.73 0.05 1 Lead - Total 0.002 Not detected 0.3 Manganese - Dissolved 23.173 0.413 6.19 Mercury - Total Not detected Not detected 0.001 Sulfate 1748.25 1728.22 3600 Total Suspended Solids 76.583 5.73 20 Zinc - Total 31.587 0.113 0.75 %.onucutrations are in parts per minion.