Section 742.215  Determination of Soil Attenuation Capacity

a)         The concentrations of organic contaminants of concern remaining in the soil shall not exceed the attenuation capacity of the soil, as determined under subsection (b) of this Section.

b)         The soil attenuation capacity is not exceeded if:

1)         The sum of the organic contaminant residual concentrations analyzed for the purposes of the remediation program for which the analysis is performed, at each discrete sampling point, is less than the natural organic carbon fraction of the soil.  If the information relative to the concentration of other organic contaminants is available, such information shall be included in the sum.  The natural organic carbon fraction (foc) shall be either:

A)        A default value of 6000 mg/kg for soils within the top meter and 2000 mg/kg for soils below one meter of the surface; or

B)        A site-specific value as measured by the analytical method referenced in Appendix C, Table F, multiplied by 0.58 to estimate the fraction of organic carbon, as stated in, Nelson and Sommers (1982) or by SW-846 Method 9060: Total Organic Carbon, as incorporated by reference in Section 742.210;

2)         The total petroleum hydrocarbon concentration is less than the natural organic carbon fraction of the soil as demonstrated using a method approved by the Agency.  The method selected shall be appropriate for the contaminants of concern to be addressed; or

3)         Another method, approved by the Agency, shows that the soil attenuation capacity is not exceeded.

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