Search for sites where contaminaion has been reported to the DNR.
Hint - Keep your search criteria general and then sift through the results
(e.g "Main" instead of "2005 E. Main St.").
Search for REGISTERED above- and underground storage tanks (ASTs and USTs).
Keep your search criteria general and please note that unregistered tanks could still exist at a property.
I think you get the idea where this link will take you.
Find general information from the DNR Remediation & Redevelopment page.
The DNR requires evaluation of the vapor intrusion pathway at many contaminated sites. Here is a link to a lot of helpful information.
This link should be good for some light nighttime reading.