The Illinois State Geological Survey (ISGS) conducts preliminary environmental site assessments (PESAs) for Illinois Department of Transportation (IDOT) road construction projects. Information on environmental conditions provided in these PESAs allows IDOT to protect worker and public safety, reduce liability, and avoid unnecessary delays.

The ISGS has recently completed a corridor study for the construction of a new highway connecting Peoria to Interstate 180 in Illinois. The new highway will provide a more direct transportation link between Peoria and Interstate 180 in La Salle. The study included the upgrading of approximately 30 miles of Illinois Route 29, as well as a corridor study for a bypass around the city of Chillicothe. The investigation included the industry-standard Phase I assessment component (historical research and site inspection), as well as a limited subsurface screening component. While most site assessments involve only one or a few parcels, this assessment covered hundreds of parcels through four towns and five counties. Seventy-six sites with potential hazards were encountered throughout the project including underground storage tank sites, petroleum pipelines, transformer sites, bulk pesticide storage sites, a railroad yard, and a large manufacturing facility. Boreholes were drilled and samples taken along state and county road right-of-way to screen for VOCs, SVOCs, heavy metals, PCBs, and pesticides at potential sites. Of the 76 sites tested, regulated substances were detected at 15 sites. IDOT will use this information on environmental conditions to assist in their project planning decisions.