New Cassel/Hicksville Ground Water Contamination

Overview

The New Cassel/Hicksville Ground Water Contamination site sits in Nassau County, New York. EPA added it to the Superfund National Priorities List in September 2011. The site is also known as the Hicksville Contaminated Ground Water Area and the New Cassel Industrial Area. Cleanup is organized into three operable units, each covering a distinct groundwater area. Construction is not yet complete at any of the units.

EPA has identified 21 contaminants of concern in groundwater at the site. The area south of Old Country Road contains chlorinated solvents including tetrachloroethene, trichloroethene, vinyl chloride, and several related compounds. The far field plume contains a broader set of chemicals, adding benzene, 1,4-dioxane, 1,2,3-trichloropropane, and others to the list. Most are volatile organic compounds, which are industrial chemicals commonly found in solvents and cleaning products. Elevated levels of these chemicals were found in 11 public water supply wells across New Cassel and Hicksville. Residents in affected areas currently receive drinking water that has been treated for these contaminants.

For the south of Old Country Road unit (OU 1), EPA selected a remedy in September 2013 using extraction wells, air stripping, carbon adsorption, chemical oxidation, and monitoring. Remedial design has been underway since 2015, with completion estimated between September and November 2027. The Sylvania/General Instrument unit (OU 2) does not yet have a cleanup decision. A combined investigation and feasibility study began in April 2014, and a Record of Decision is estimated between March and May 2028. For the far field plume unit (OU 3), EPA completed the investigation and feasibility study in March 2024 and issued a Record of Decision on March 29, 2024. Remedial design for OU 3 is estimated to start between September and November 2026. EPA notes that human exposure and groundwater migration both have insufficient data, meaning there is uncertainty about whether exposures are controlled and whether contaminated groundwater migration is stabilized.

EPA held a virtual community meeting on June 24, 2024, to present the selected cleanup plan for a portion of the site. Community members can review the April 2024 Community Update Fact Sheet and the Record of Decision for more details. Site records are available at EPA's New York office at 290 Broadway, 18th floor, New York, NY 10007, and at the Westbury Public Library Reference Section, 445 Jefferson Street, Westbury, NY 11590. For direct questions, community members can contact EPA's Community Involvement Coordinator or Remedial Project Manager using the contact information below.