Special Projects

Special Projects

Central Illinois Ground Water Contamination Source Investigation

For several decades Illinois EPA has been keeping a watchful eye on contamination within the aquifer used by Nokomis, Illinois for drinking water.  Contaminants such as Tetrachloroethylene (PCE), benzene, vinyl chloride, Methyl Tertiary-Butyl Ether (MTBE) had been found in groundwater beneath the municipality.  With the help of a loan from Illinois EPA the village installed a new water treatment plant in 1998 equipped to remove contaminant concentrations to levels below federal drinking water standards. The equipment in the new treatment facility was (and continues to be) successful at treating the incoming water and distributing safe drinking water to residents.  However, contaminants continued to be found in groundwater throughout the village.

Illinois EPA Office of Site Evaluation conducted a series of investigations to identify the flow direction of water and identify potential sources for these contaminants still in the drinking water.  OSE installed a combination of monitoring wells and piezometers at 21 locations throughout the village to sample for contaminants and characterize groundwater flow direction.  Water levels obtained from community water supply wells, Geoprobe temporary well-point locations, and OSE’s network of wells and piezometers were used by Illinois EPA’s Bureau of Water to model flow direction using geographic information systems (GIS). 

Using the results of multiple rounds of groundwater sampling and flow direction analysis, Illinois EPA was able to identify multiple sources of contamination to the groundwater used by Nokomis for their public water supply.  Their data findings on several different areas allow for potential remediation and other necessary steps to occur to ensure that the drinking water in Nokomis, IL is continues to be completely free of these contaminants.