Superfund Information Systems: Site Profile

Superfund Site:

ORE KNOB MINE
ASHE COUNTY, NC

Cleanup Activities

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Background

The Ore Knob Mine site is located in Jefferson, North Carolina. It includes areas affected by copper mining operations from the 1850s to 1962. The U.S. Environmental Protection Agency placed the site on the Superfund program’s National Priorities List (NPL) in 2009 because of contaminated surface water, groundwater, sediment and soil. EPA and the North Carolina Department of Environmental Quality (NCDEQ) have investigated site conditions and taken steps to clean up the site. This cleanup will protect people and the environment from contamination.

It was found in 2010 that many residences surrounding the site had tap water contaminated with high concentrations of metals and acid (manganese, iron, cobalt, acidity). This suggests that water is migrating from the mines through faults, fractures, and pore spaces in the bedrock into nearby drinking water wells.

EPA has attempted to identify all affected drinking water wells and provide bottled water or well treatment systems where needed. EPA conducts annual well water sampling on properties identified as being in the zone of concern. The purpose of the sampling is to ensure that whole house filter system is removing contamination present in drinking water related to the Ore Knob Mine Superfund Site and to evaluate if any further response actions are necessary to protect public health and the environment.

EPA has also completed an emergency response action to stabilize a tailings impoundment dam. [Tailings are the materials left over after the process of separating an ore.] The response action will prevent a catastrophic release of tailings into nearby streams and rivers. In February 2015, EPA completed an investigation and determined a municipal water line will be extended about 8 miles from the Town of Jefferson through Ashe County to affected residents near the Ore Knob Mine Site. EPA is also conducting an investigation to assess other affected parts of the site for long-term site cleanup options. These parts include soils, surface water and sediment.

 


About the site:

The site is located in Ashe County, North Carolina, approximately 12 miles south of the Virginia state line, 45 miles southeast of Bristol, Tennessee, and eight miles east of Jefferson, North Carolina. The area hosted intermittent mining of copper ore from the 1850s through 1962, with most mining occurring from 1873 to 1883 and from 1957 to 1962. The site includes three principal areas and several downstream areas.

  1. The 15-acre 1950s Mine and Mill Area is located northwest of the intersection of Ore Knob Road and Little Peak Creek Road, just north of Highway 88. This area contains derelict ore bins, concrete mill foundations, a transformer building, other ruins, tailings and a 2-acre former pond where process water was stored.
  2. The 19th Century Operations Area and the Main Tailings Impoundment Area are located across Little Peak Creek Road, at the end of Ore Knob Mine Road. The Main Tailings Impoundment Area is located about 0.3 miles northeast of the 19th Century Operations Area.
  3. The 19th Century Operations Area includes a series of barren and nearly barren stretches of land (totaling about 5 acres) near the top of Ore Knob. This land contains waste rock dumps from at least 11 mineshafts as well as former ore smelting locations.

The Main Tailings Impoundment Area contains an estimated 720,000 cubic yards of tailings. These tailings contain high levels of metals, including copper, zinc, iron, arsenic and mercury. Tailings are the waste material left over after mining operations have extracted minerals from ore mined at the site. The tailings can be a source of acid mine drainage, which can damage streams, rivers and other water bodies.

All mining was conducted underground through underground mine workings to access the ore. Underground mine workings are now partly flooded with ground water to a depth of approximately 130-feet below ground surface. The underground mine workings are more than 4,000 feet long and more than 1,000 feet deep. These workings exposed the ore containing sulfur bearing minerals to air and moisture. Air and water react with the ore and produce acid which in turn releases metals into the groundwater. Underground pools of mine-impacted water provide a continuing source of contamination to groundwater down-gradient of the underground mine workings.

This contamination would define a “plume” that migrates away from the contaminant source with time. It was found in 2010 that many residences surrounding the site had tap water contaminated with high concentrations of metals and acid (manganese, iron, cobalt, acidity). This suggests that water is migrating from the mines through faults, fractures, and pore spaces in the bedrock into nearby drinking water wells. EPA became involved at the site when this contamination was discovered and began providing bottled drinking water to affected residents as well as in-house water treatment systems. EPA is currently in the process of extending a municipal waterline approximately 8 miles from the Town of Jefferson, North Carolina to the affected residents.

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What Has Been Done to Clean Up the Site?

EPA and the NCDEQ have investigated site conditions and taken steps to clean up the site in order to protect people and the environment from contamination.  EPA leads site investigation and cleanup activities in cooperation with NCDEQ.

  • From April 2010 through June 2012, EPA sampled 79 potable water sources (64 private wells and 15 springs) in order to determine the extent of contaminated or potentially contaminated private drinking water wells.
    • EPA installed or upgraded 15 whole house treatment systems.
    • EPA will continue collecting samples from private drinking water wells as necessary to assess whether site contamination might be affecting additional wells. EPA also samples whole-house well treatment systems annually and potential at risk water sources to make sure the treatment systems are working properly.
    • EPA has attempted to identify all affected drinking water wells and provides bottled water or well treatment systems where necessary.

In 2011, EPA completed an emergency response removal action to stabilize the Main Tailings Impoundment Area dam and prevent a catastrophic release of tailings into downstream waters. Specific actions included:

  • Analyzing the face of the Main Tailings Impoundment Area dam.
  • Removing 16,000 cubic yards of tailings from the Main Tailings Impoundment Area sediment pond so the pond could continue to capture new sediment.
  • Constructing a diversion channel to direct storm water around the Main Tailings Impoundment Area to minimize erosion of the dam face and acid mine drainage.
  • Filling in four ponds near the Main Tailings Impoundment Area to reduce surface water infiltration.
  • Re-facing the Main Tailings Impoundment Area dam.
  • Removing 60,000 cubic yards of mine tailings from the tailings dam at the 1950s Mine and Mill Area.
  • Constructing catchment basins to minimize the flow of sediment into the diversion channel.
  • Reconstructing the sediment pond embankment to provide more stability and increase sediment pond capacity.

If EPA and NCDEQ are able to fully address the Town of Jefferson's concerns regarding the municipal water line, it will be extended approximately 8 miles from the Town of Jefferson through Ashe County to affected residents near the Ore Knob Mine Site.

EPA will issue the final cleanup plan (a Record of Decision, or ROD) which addresses any long-term contamination and related risks to people and the environment. After issuing the plan, EPA will begin preparations to carry out the approved long-term cleanup activities.

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What Is the Current Site Status?

In 2011, EPA completed an emergency response removal action to stabilize the Main Tailings Impoundment Area dam and prevent a catastrophic release of tailings into downstream waters.

In February 2015, EPA completed an investigation, referred to as an engineering evaluation/cost analysis (EE/CA), to determine a permanent alternate water source for people affected by ground water contamination from the site. EPA signed the Action Memorandum to implement the preferred alternative from the EECA: Drinking Water Alternative 4, Municipal Water Supply. A municipal water line will be extended approximately 8 miles from the Town of Jefferson through Ashe County to affected residents near the Ore Knob Mine Site. EPA is currently in the design phase on implementing the waterline remedy and plans to begin construction by 2019.

EPA is also conducting an investigation to assess other affected parts of the site, including surface water, soils, and sediment for long-term site cleanup options. EPA is currently investigating surface water contamination at the site. After completing the site’s remedial investigation/feasibility study, EPA will issue a proposed cleanup plan to address any long-term contamination and related risks to people and the environment. After receiving input from the North Carolina Department of Natural Resources and Environment (NCDENR) and the community, EPA will issue the final cleanup plan (a Record of Decision, or ROD). After issuing the plan, EPA will begin preparations to carry out the approved long-term cleanup activities.

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Sampling and Monitoring

EPA is conducting a remedial investigation/feasibility study to assess other affected parts of the site, including surface water, soils and sediment for long-term site cleanup options. EPA continues to conduct annual sampling of private wells of the affected residences.

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Enforcement Information

EPA has identified several potentially responsible parties (PRPs) associated with the site. EPA is engaged in ongoing enforcement activities. On November 9, 2010, EPA published notice of a proposed Settlement Agreement with one site PRP, The Marsh Foundation, Inc., and invited public comments.

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