Tysons Dump is a 4-acre former waste disposal site in Upper Merion Township, Pennsylvania. From 1962 to 1973, septic and chemical waste were dumped into unlined lagoons there. The EPA added the site to the National Priorities List in September 1984, which triggers a formal cleanup process. The site has not yet been deleted from that list.
The contamination covers several media. Groundwater contains volatile organic compounds including toluene, xylene, ethylbenzene, and chlorinated compounds such as 1,2,3-trichloropropane. Soil holds benzene, toluene, ethylbenzene, and phenothiazine. Sediment contains petroleum residue and heavy metals including arsenic, lead, mercury, chromium, cadmium, and others. Contamination has been detected in the Schuylkill River and in groundwater beyond the site boundary.
Companies identified as potentially responsible parties include Ciba-Geigy Corp., Wyeth Labs Inc., Essex Group Inc., and SmithKline Beckman Corp. Working with the EPA, these parties carried out several cleanup actions. A soil vapor extraction system ran from 1988 to 1996. A groundwater extraction system along the Schuylkill River started operating in May 1990 and has since prevented site contaminants from reaching the river. Additional extraction wells were added in December 1997 to address contamination in the deeper aquifer. A wet soil cover was completed by August 1997 to control vapor migration. Construction across the site's five operable units was substantially complete by December 1997.
The site is now in long-term operation and maintenance. All local residents are connected to the public water supply, so drinking contaminated groundwater is not a current exposure pathway. Institutional controls restrict site access and prohibit groundwater use in the affected aquifer. Zoning restrictions also prevent residential development at the site. The EPA's 2024 five-year review found the remedy continues to protect human health and the environment in the short term, with recommendations made for long-term protectiveness. The next five-year review is scheduled for 2029.
Community members can get involved through the EPA's Community Involvement Program, which supports participation in cleanup decisions. Questions about the site can be directed to the Community Involvement Coordinator or the Remedial Project Manager. Site records are available online, at the Upper Merion Township Library at 175 West Valley Forge Road in King of Prussia, or at the EPA Region 3 office in Philadelphia at 1600 John F. Kennedy Boulevard. Appointments to review records can be made by calling 215-814-2396.
