CIRCLEVILLE, Ohio — New environmental data submitted to state regulators shows that groundwater contamination tied to the PPG Industries facility in Circleville continues to exceed federal cleanup limits.
According to documents filed with the Ohio Environmental Protection Agency on Sept. 11, 2025, concentrations of 1,4-dioxane, a likely human carcinogen, remain above the state’s cleanup criterion of 4.6 micrograms per liter in several monitoring wells located downgradient of the site.
Sampling conducted in July 2025 found levels of 7.4 µg/L at monitoring well 6, 7.6 µg/L at monitoring well 7, and 7.6 µg/L at the DuPont MW-10 well field near the Earnhart Hill Regional Water and Sewer District — all above the state’s threshold for remediation.
The data were compiled by Tetra Tech Inc. on behalf of PPG and analyzed by Eurofins Cleveland Laboratory. The letter to Ohio EPA states that while some concentrations have declined slightly since May, contamination persists across the same wells that have exceeded limits for years.
PPG recently restarted recovery well RW-5, which had been offline, to help capture the plume along the southern boundary of the Earnhart Hill property. The company told regulators that increased pumping from RW-4 and RW-5 is expected to gradually reduce the chemical concentrations “over the next several months.”
Records show that the contaminated plume has been monitored since at least 2002, when early testing detected 1,4-dioxane in the same groundwater system. Despite intermittent declines, concentrations near Earnhart Hill have frequently stayed above the cleanup standard for more than two decades.
The chemical 1,4-dioxane is used as an industrial solvent and stabilizer. It is highly mobile in groundwater and does not readily break down in the environment. The U.S. EPA classifies it as a probable human carcinogen linked to liver and kidney damage.
The next sampling round is scheduled for November 2025, with a semiannual report due later that month.
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