Impact of rainfall, snowpack and storms on contaminant levels in groundwater beneath two U.S. Superfund sites in New York

Superfund sites are polluted locations in the U.S. designated by the Environmental Protection Agency for cleanup due to hazardous waste contamination. The U.S. Government Accountability Office estimates that 50% of U.S. Superfund sites are at risk of flooding, potentially leading to mobility of contaminants into the environment. We investigate the relationships between rainfall, snowpack, and storms with levels of contaminants in well water beneath Dzus Fasteners Co. in West Islip, New York (NY, 2011-2019) and American Thermostat Co. in South Cairo, NY (2005-2011) using data shared by the New York State Department of Environmental Conservation. At Dzus, sampling was conducted approximately yearly. During Superstorm Sandy in October 2012, the water table beneath Dzus rose 1 to 2 meters due to storm surge, then receded into the Atlantic Ocean via Willetts Creek. In a Dzus monitoring well (MW), cadmium (Cd) increased from 64.4 µg/L in August 2012, to 120 µg/L in November 2013; lower levels of Cd were seen in other MWs. In April 2013, after Sandy, 14 out of 70 sediment samples collected along Willetts Creek were above 90 mg/kg Cd, with a maximum of 1,600 mg/kg; the previous maximum was 133 mg/kg. At American Thermostat, positive correlations were detected between volatile organic compounds and both rainfall and snowpack in three out of six observation wells. For example, in well observation well 12, snowpack showed strong correl ati ons wi th the on-si te mai n contami nants: tri chl oroethyl ene (r = 0. 96) and tetrachloroethylene (r = 0.86). Despite limited sampling data, these case studies suggest that contaminant levels in groundwater and nearby sediment at Superfund sites can increase with rainfall, snowpack, and intense storms. Increased monitoring frequency is recommended to better understand the impacts of storms and precipitation at Superfund sites.