Ambient and Landfill-Impacted Groundwater Quality in the Hudson Valley of Southeastern New York State

A large amount of groundwater quality monitoring data has been collected in connection with solid waste landfills regulated by the New York State Department of Environmental Conservation. Although sampling personnel and analytical laboratories are different for each site, a high degree of uniformity in methods is assured by state regulations which govern environmental monitoring at the landfills. In this study, data for selected parameters was pooled from upgradient, presumably uncontaminated, monitoring wells installed in different rock formations at a large number of sites in order to characterize regional variability in ambient groundwater quality. Parameters selected for this study are those considered to be most useful in detecting landfill-derived groundwater contamination and include alkalinity, ammonia, arsenic, chloride, chemical oxygen demand, hardness, iron, manganese, total phenols and total dissolved solids. Comparisons are made with data from monitoring wells downgradient of the landfills and with other available data sets. Emphasis is placed on whether parameters exceed applicable water quality standards in ambient groundwater and whether the parameters selected are reliable indicators of landfill-derived groundwater contamination. This study should be particularly useful in cases where topography, property boundaries or other site constraints make it impossible to site a valid upgradient monitoring point or where groundwater quality impact assessments must be made using a single monitoring point.