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.
A 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 the Illinois Department of Transportation (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).
