Groundwater cleanup near the New Cassel industrial area expected to cost $22.9 million
The U.S. Environmental Protection Agency (EPA) has finalized its plan to clean up a portion of contaminated groundwater beneath the New Cassel/Hicksville Ground Water Contamination Superfund site  in the towns of Hempstead, North Hempstead and Oyster Bay in Nassau County, N.Y. Groundwater at the site is contaminated with harmful volatile organic compounds (VOCs), which are often found in paint, solvents, aerosol sprays, cleaners, disinfectants, automotive products and dry cleaning fluids. Repeated and direct exposure to VOCs can damage health.
Because of the nature and complexity of the contamination at the site, the EPA is dividing the investigation and cleanup into phases. The plan is the first EPA phase of the cleanup and specifically addresses one portion of the site. EPA held a public meeting in the town of Westbury on Aug.15, 2013, to explain its plan. It received public comment for 60 days and considered public input before finalizing the plan.
The Magothy aquifer, Nassau County’s primary source of drinking water, has been contaminated by the VOCs. This contaminated drinking water has been treated since 1990 before it is provided to area residents. The water supply is monitored regularly to ensure that the water quality meets federal and state drinking water standards.
Testing by EPA in 2010 confirmed the presence of elevated levels of VOCs in the groundwater feeding 11 public water supply wells: six in Hicksville, four in Hempstead and one in Westbury. The site was added to the federal Superfund list of contaminated hazardous waste sites in 2011.
The final cleanup plan for this portion includes construction of a plant to extract and treat groundwater contaminated with VOCs above a specific level. If used to full capacity, the treatment plant would treat up to 500,000 gal per day. In some areas, a vapor stripper would be used on individual wells to force air through contaminated groundwater to remove the VOCs. The air in the stripper causes the chemicals to change from liquid to gas, which is then collected and cleaned. Depending on the results of a study, the most heavily contaminated groundwater would be treated using a process such as chemical oxidation to break down the harmful contaminants into water and byproducts such as carbon dioxide. The oxidants would be pumped into the groundwater at different depths in the contaminated area. Each injection would be followed by monitoring to evaluate the effectiveness of the treatment, and EPA will require periodic collection and analysis of groundwater samples to verify that the levels and extent of contaminants are declining.
EPA estimates the cost of this cleanup will be about $22.9 million. Consistent with EPA policy, the agency will seek to engage those parties legally responsible for the contamination in implementing the cleanup at the site.