MacKenzie Chemical Works operated as a chemical products manufacturer in Central Islip, New York from 1948 until 1987, producing items such as fuel additives. The facility stored hazardous materials in tanks and drums and experienced multiple spills and fires over the years. EPA added the site to the National Priorities List (NPL) in 2001, which identifies contaminated sites that need long-term cleanup under the federal Superfund program.
The site has 24 confirmed contaminants of concern found in both soil and groundwater. Groundwater contains metals including aluminum, antimony, arsenic, cadmium, chromium, iron, and manganese, along with organic chemicals such as benzene, chloroform, trichloroethene, and chlorinated propanes. Soil contamination includes polycyclic aromatic hydrocarbons like benzo[a]pyrene and benzo[a]anthracene, the pesticide dieldrin, and other organic compounds. The company also stored 1,2,3-trichloropropane in three 10,000-gallon on-site tanks.
EPA selected a cleanup remedy in March 2003. That plan included soil vapor extraction (SVE) to pull volatile organic compounds out of contaminated soil, excavation of other contaminated soils, removal of the former laboratory building, and groundwater treatment using air sparging with ozone injection. The SVE system ran from 2004 through 2016, then continued on an as-needed basis. In 2020, the top five feet of remaining contaminated surface soil was excavated and removed off-site, and the SVE system was decommissioned. For groundwater, chemical oxidation injections have substantially reduced contamination levels, with the most recent injection completed in 2016. The New York State Department of Environmental Conservation is currently evaluating whether additional injections are needed.
Construction of the cleanup was completed in October 2006. The site was declared ready for anticipated reuse on September 30, 2020. Human exposure is under control, and groundwater migration is stabilized with no unacceptable discharge to surface water. EPA's most recent five-year review, completed in January 2022, confirmed the remedy continues to protect human health and the environment. The next five-year review is scheduled between January and March 2027. The site remains on the NPL and has not yet been deleted.
Community members who want to follow cleanup progress or ask questions can contact EPA directly. Site documents are available online through EPA's Superfund database, in person at the EPA Superfund Records Center at 290 Broadway in New York City, at the Central Islip Public Library at 33 Hawthorne Street, or at the New York State Department of Environmental Conservation Region 1 Office on the SUNY campus in Stony Brook.
