The geologic and hydrologic characteristics of the sand-and-gravel deposits that compose the glacial drift aquifer in the vicinity of the Nelson Landfill site in Yorkville, Illinois indicate that the aquifer could be developed as a source of public water supply. The geology of these deposits within the Newark Bedrock Valley is complex, however, and a detailed investigation of their water bearing and transmitting properties will be required to successfully locate high-capacity wells.
Volatile organic compounds, pesticides, and cyanide were not detected in ground water during this investigation. Metals and nitrogen compounds were not detected at concentrations above their Maximum Contaminant Level. Iron, manganese, and aluminum were detected at concentrations above their Secondary Maximum Con-taminant Level and various constituents were detected at concentrations above background levels downgradient of the landfill. Nitrate and ammonia, presumably derived from agricultural practices, also were detected in samples from locations hydraulically upgradient of the landfill.
Oxidation-reduction conditions in the aquifer become more reducing with depth. This change is reflected by a change in the type of nitrogen compound detected and the concentration of dissolved oxygen and iron in the glacial drift aquifer. Concentrations of some of the major ions and metals may be affected by dissolution of carbonate minerals in the aquifer and perhaps road salts.
