The Iowa Department of Natural Resources (DNR) regulates sites contaminated by petroleum releases from underground storage tanks. These are known as leaking underground storage tank sites. The regulated materials Section has oversight for the investigation, remediation and monitoring of contaminated DOT sites utilizing a statewide environmental service contract. The Iowa DOT’s leaking tank sites have consisted of current and former DOT maintenance garage properties and parcels acquired as part of highway construction projects.
Upon review of site conditions outlined in investigation and monitoring reports, the DNR assigns risk classifications specific to each site. These classifications can be "High", "Low" and "No Action Required". High-risk sites typically require some form of corrective action, Low risk sites typically require monitoring (semi-annual or annual sampling and reporting), and No Action Required sites have met the DNR’s site closure requirements.
The Iowa DOT has worked through the regulatory requirements to obtain closure for its leaking underground storage tank sites.