Paper No. 15
Presentation Time: 5:00 PM-7:00 PM
RESUMING GROUNDWATER WITHDRAWAL FOR PUBLIC WATER SUPPLY IN QUEENS COUNTY, NEW YORK CITY
For many years, groundwater for public water supply was withdrawn from the wells of the Jamaica Water Supply Company in Queens County, NYC. These wells were shut down, for the most part, in 1996. Since that time, water table elevations in the area have risen significantly causing some high groundwater problems. The New York City Department of Environmental Protection (NYCDEP) has held public hearings on the contemplated resumption of ground water withdrawal in Queens County, presumably to supplement surface water supply and to draw down the water table. One possible problem with the planned resumption of withdrawal is a site in the area which is contaminated with trichloroethylene (TCE) and perchloroethylene (PERC). The site was previously used as a storage and distribution center for dry cleaning establishments. This included the storage of TCE in above ground tanks. Improper handling of the stored chemicals led to a release of TCE that impacted the soil and groundwater at the site. The site was listed in the New York State Registry of Inactive Hazardous Waste Sites in August 1997, and now, a slow-moving plume of TCE-contaminated groundwater extends beyong the boundaries of this site. These pollutants must be isolated from proposed water supply wells to protect them from contamination. Water treatment processes including Oxidation and Filtration, Air Stripping , Activated Carbon Sorption and Reverse Osmosis are contemplated by the NYCDEP for clean-up operations. The NYCDEP is contemplating a recovery well to hydraulically isolate the area of contamination from the proposed supply wells. Monitoring wells have been installed on the campus of York College of CUNY to establish baseline water table conditions prior to the proposed recovery well operation. This may help to determine the efficacy of any subsequent recovery well operation by measuring changes in the water table elevation and gradient. It also offers York College students a real-world look into groundwater monitoring that can not be done in any classroom. Although the surface water supply for New York City is usually adequate, there are drought years, such as 2002, during which water supply emergencies may be declared. The ultimate goal of the NYCDEP is to integrate the newly purified groundwater into the City's water supply system as necessary.