Leonard Chemical Co., Inc. operated a hazardous waste treatment facility on a 7-acre property in Rock Hill, South Carolina from the late 1960s until a York County court order forced it to close in 1983. The U.S. Environmental Protection Agency (EPA) added the site to the Superfund National Priorities List (NPL), a roster of the country's most contaminated sites, in 1984. The site is fenced and not currently in use.
EPA has identified 33 contaminants of concern spread across both soil and groundwater. These include volatile organic compounds (VOCs) such as trichloroethene, tetrachloroethene, and vinyl chloride. Semi-volatile organic compounds like bis(2-ethylhexyl)phthalate and dibutyl phthalate are also present, along with heavy metals including arsenic, cadmium, chromium, lead, mercury, and manganese. The contamination traces back to the facility's practice of separating wastes through boiling and placing residues in three main areas on the property.
Cleanup began with a voluntary surface removal in 1983 that cleared more than 3,900 drums and tanks. EPA approved a formal cleanup plan in 2001 for the single operable unit (OU01). That plan uses soil excavation, soil vapor extraction (pulling contaminants out of subsurface soil), and air sparging (injecting air into groundwater to break down VOCs). Phase I soil removal ran from 2010 to 2014 and took out 1,934 tons of contaminated soil. Additional extraction and air sparge wells were added in later phases. From November 2010 through mid-2024, the treatment system removed roughly 28,409 pounds of VOCs. Groundwater is monitored annually, with the next sampling set for October 2025.
EPA assessments confirm that human exposure is currently under control and there are no unacceptable exposure pathways at this time. Groundwater contamination migration is also under control, and EPA has found no unacceptable discharge to nearby surface water. Physical construction is not yet complete, however. EPA estimates construction will finish between April and June 2028, and the site is expected to be ready for reuse between September and November 2028. Zoning restrictions prevent residential use, and fencing limits public access in the meantime.
Community members can stay involved through public notices, public meetings, and interviews that EPA holds throughout the cleanup process. Direct questions can be directed to the Community Involvement Coordinator or the Remedial Project Manager.
