DETERMINING THE SOURCE OF SALT CONTAMINATION IN GROUNDWATER IN VERNON CENTER, NEW YORK

Three homes near Vernon Center, New York use bottled water because of concentrations of sodium and chloride of up to 5700 mg/l and TDS of up to 12,000 mg/l in their well water. The bottled water is provided by the New York State Department of Transportation (NYSDOT) because an abandoned road salt storage and reloading facility located approximately 500 m upgradient from the homes is believed to be the source of the contamination. The salt was stored on an unlined and uncovered surface and the facility was used for at least thirty years.

We used electromagnetic induction as a proxy to determine the relative salt content of the soil and shallow groundwater in the area. In addition, we analyzed water samples from six monitoring wells installed downgradient from the storage site, two monitoring wells upgradient from the site, five domestic wells, and a nearby stream. Our results suggest that salt contamination from the storage area is limited to the area immediately adjacent to the site and doesn’t appear to have migrated to the homes or the stream. While several of the domestic wells are contaminated with salt, several wells in the same area have very low salt concentrations. There appears to be a strong correlation between well depth and salt concentration; wells that are drilled deeper than 21 m (70ft) are have high concentrations of salt. While it’s possible that salt from the storage facility affected the wells in the past, our results show that this is not happening now. We believe that a more likely source of the salt is naturally occurring salt in the Paleozoic sedimentary rocks that underlie the area. Wells that are drilled to depths that intersect the salt-containing rock have become contaminated. Preliminary results of numerical modeling are consistent with this interpretation.