Highway Authority Agreements

An agreement with a highway authority may be used where a property owner has contaminated public right-of-way or where the public right-of-way may become impacted in the future. Highway Authority Agreements (HAA) may be used as an institutional control where the requirements of Title 35 of the Illinois Administrative Code, Section 742 (35 Ill. Adm. Code 742) are met and the Illinois Environmental Protection Agency (IEPA) has determined that no further remediation is required for the property.

HAA applicant should use Equation R26 in accordance with 35 Ill. Adm. Code 742.810 to demonstrate that the concentration of any contaminant of concern in groundwater will meet the applicable Tier 1 Class I groundwater remediation objective. Equation R26 predicts the contaminant concentration along the centerline of a groundwater plume emanating from a contaminant source in the aquifer. For HAAs with IDOT, the agreement area should include all highway jurisdictional property predicted radially from the concentration source (Cs) to a distance X that meets the Tier 1 groundwater remediation objectives for the direct ingestion of Class I groundwater presented in 35 Ill. Adm. Code 742, Appendix B, Table E of TACO (Cx).