35 Ill. Adm. Code 742.400
Area Background
Section 742
Section 742.400 Area
Background
This Subpart provides procedures
for determining area background concentrations for contaminants of concern.
Except as described in Section 742.415(c) and (d) of this Subpart, area
background concentrations may be used as remediation objectives for contaminants
of concern at a site.