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The 185-acre Henry’s Knob Superfund Site is located at the corner of State Highway 55 and Henry’s Knob Road in Clover Township, York County, South Carolina. The Henry’s Knob Site was an open pit kyanite mine that operated from 1947 to 1970. Kyanite is primarily used in producing refractory, ceramic and porcelain materials that withstand high temperatures. Mining activities included crushing and grinding rock and then recovering kyanite from the crushed ore. Waste rock and tailings, which remained from the processes, contained elevated levels of metals.
The former mining process contaminated groundwater over an area of 47 privately-owned parcels of land, which also includes 24 homes. Of these 24 homes, six were found to have groundwater contamination above Removal Management Levels (RMLs) for manganese and/or cobalt. The mining activities contributed to the higher levels due to acidic generation pyritic rock, increased the leaching of metals into groundwater.
The site was deeded to York County in 1974 and was used as a park for several years. York County sold the property in 1982, and the site was privately owned until 2015. To facilitate remedial activities associated with the site, in August 2015, ABB Inc. (ABB) completed the purchase of portions of the property where the tailings impoundments are located.
What Has Been Done to Clean Up the Site?
The main drinking water contaminants are manganese and cobalt. In 2012, after a public comment period, EPA selected extending a public water supply line as the preferred remedy. The public water supply system in Clover would be extended to the affected homes in the Henry's Knob community to provide a permanent solution to drinking water concerns.
In September 2012, EPA proposed that the Town of Clover extend the water line to the Henry's Knob area. In April 2013, the Town of Clover notified EPA that they did not support the water line extension option due to economics and the low number of homes to service. Public response was also not favorable. In October 2013, EPA issued a revised plan to install wellhead treatment systems on individual drinking water wells. The treatment systems neutralize and soften the water pumped from residential wells. Treatment systems were offered to 30 homes located up to 250 feet beyond the area of potentially impacted groundwater. To date, ABB has installed 18 treatment systems on residential wells. ABB has also extended offers to other residents with the affected area.
The Remedial Investigation Report identified ten Areas of Concern (AOC). These include:
- Area 1 - West Tailings Ponds
- Area 2 - North Tailings Ponds
- Area 3 - Former Mill Operations Buildings
- Area 4 - Mine Pit Pond
- Area 5 - East Tailings Ponds
- Area 6 - South Fork of Crowders Creek
- Area 7 - Random Dumping Areas
- Area 8 - Waste Rock Area (North Side)
- Area 9 - Waste Rock Area (South Side), and
- Area 10 - Site Groundwater.
ABB, with EPA oversight, began remediation stabilization work in 2015. To date, four major portions of the site have been stabilized. These include AOCs 1, 2, 3, and 5.
|5||Like AOCs 1 and 2||December 2017|
The grasses have grown and wildlife has returned to the areas. It is expected that the new vegetation will reduce infiltration of storm water through the tailings to groundwater.
The completion of AOC 5 marked the end of stabilization work at the site. The remainder of the AOCs will be addressed in a future cleanup plan.
What Is the Current Site Status?
ABB is currently preparing the Feasibility Study for the site. This stage of the Superfund process involves evaluating potential performance and cost of treatment options identified for a site.
In late 2018, EPA plans to send out a Proposed Plan to the community that will identify cleanup options that EPA will consider implementing. Following a public comment period, EPA will issue a final Record of Decision (ROD) which will select the cleanup plan. EPA currently plans to issue the ROD in February 2019.