EPA to cleanup Nassau County groundwater contaminated with harmful VOCs
The U.S. Environmental Protection Agency (EPA) announced its proposed plan to clean up an area of contaminated groundwater within 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 throughout these areas 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 cause serious health effects.
The Magothy aquifer, Nassau County’s primary source of drinking water, has been contaminated by the VOCs. This contaminated water is currently being treated 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.
Because of the nature and complexity of the contamination at the site, 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 will hold a public meeting on Aug. 15 at the Community Center, 141 Garden Street, Westbury, N.Y., to explain the plan. Public comments will be accepted until Aug. 26, 2013.
Groundwater testing by EPA in 2010 confirmed the presence of elevated levels of VOCs in groundwater feeding 11 public water supply wells: six in Hicksville, four in Hempstead and one in Westbury. Based on past water quality monitoring results, public water supply companies installed treatment systems that remove VOCs from the contaminated groundwater. The site was added to the federal Superfund list of contaminated hazardous waste sites in 2011.
The proposed cleanup plan includes construction of a treatment plant to extract and treat groundwater contaminated with VOCs above a specific level. If used to full capacity, the system will treat up to 500,000 gal per day. In some areas, a vapor stripper that forces air through polluted groundwater to remove harmful chemicals will be used on individual wells. The air causes the chemicals to change from liquid to gas, which is then collected and cleaned. In the most heavily contaminated areas, the groundwater will be treated using a treatment process such as chemical oxidation, which uses chemicals to destroy pollution in groundwater, breaking down the harmful chemicals into water and carbon dioxide. The oxidants are pumped into the groundwater at different depths in the polluted area. Each injection is followed by monitoring to evaluate the effectiveness of the treatment. Samples of the groundwater will be collected and analyzed to ensure that the technology is fully effective.
EPA will require periodic collection and analysis of ground water samples to verify that the levels and extent of contaminants are declining. The agency will conduct a review every five years to ensure the effectiveness of the cleanup.