Highlands Acid Pit

Overview

The Highlands Acid Pit is a 3.3-acre Superfund site in Highlands, Texas, added to the National Priorities List in September 1983. In the 1950s, an unknown quantity of industrial waste sludge from oil and gas refining, believed to be spent sulfuric acid, was disposed there. That waste contaminated both soil and groundwater with hazardous chemicals. The site is also known as the Johnson Acid Pit and sits in Harris County within Congressional District 36.

EPA has identified 19 contaminants of concern across two areas. The source area, called Operable Unit 01, contains benzene, beryllium, chromium, lead, manganese, toluene, and xylene in solid waste and groundwater. The groundwater area, Operable Unit 02, contains arsenic, benzene, cadmium, chromium, lead, pyridine, and sulfuric acid in groundwater.

Cleanup began in 1984 with the excavation of 22,200 cubic yards of waste and contaminated soil, which was removed off-site for disposal. The excavated area was backfilled and revegetated, and a fence was installed. Construction of the primary remedy finished in June 1992. For groundwater, EPA selected a monitored natural attenuation approach in 1987, meaning contamination is tracked over time to verify it is breaking down or staying contained naturally. A deed notice was put in place as an institutional control. A new groundwater remedial investigation started in August 2024 and is estimated to finish between June and August 2028.

Human exposure is currently under control, with no unacceptable exposure pathways identified. Groundwater migration is also under control, with contaminated groundwater stabilized in its original area and no unacceptable discharge to surface water. The site is not yet sitewide ready for anticipated use, though redevelopment is occurring on portions of it. The site is estimated to be ready for anticipated reuse between September and November 2027. A five-year review completed in June 2023 found the site short-term protective but identified actions needed for long-term protection. The next five-year review is estimated for June to August 2028.

Community members can review site records at the Highlands Public Library, Stratford Branch, at 509 Stratford Street in Highlands, Texas. The full five-year review report is also available online. For questions, residents can contact the EPA Community Involvement Coordinator. For state-related questions, contact the Texas Commission on Environmental Quality.