Section 742.415  Use of Area Background Concentrations

a)         A person may request that area background concentration determined pursuant to Sections 742.405 and 742.410 be used according to the provisions of subsection (b) of this Section.  Such request shall address the following:

1)         The natural or man-made pathways of any suspected off-site contamination reaching the site;

2)         Physical and chemical properties of suspected off-site contaminants of concern reaching the site; and

3)         The location and justification of all background sampling points.

b)         Except as specified in subsections (c) and (d) of this Section, an area background concentration may be used as follows:

1)         To support a request to exclude a chemical as a contaminant of concern from further consideration for remediation at a site due to its presence as a result of background conditions; or

2)         As a remediation objective for a contaminant of concern at a site in lieu of an objective developed pursuant to the other procedures of this Part.

c)         An area background concentration shall not be used in the event that the Agency has determined in writing that the background level for a regulated substance poses an acute threat to human health or the environment at the site when considering the post-remedial action land use. (Section 58.5(b)(3) of the Act)

d)         In the event that the concentration of a regulated substance of concern on the site exceeds a remediation objective adopted by the Board for residential land use, the property may not be converted to residential use unless such remediation objective or an alternative risk-based remediation objective for that regulated substance of concern is first achieved.  If the land use is restricted, there shall be an institutional control in place in accordance with Subpart J. (Section 58.5(b)(2) of the Act)

(Source:  Amended at 31 Ill. Reg. 4063, effective February 23, 2007)