By: R. Scott Stoldt, CPG, LPG, PG – Director of Investigation & Remediation Services


IDEM’s 2020 Screening Level Tables (Table A-6 and A-7), effective March 2, 2020, are now available on IDEM’s Screening and Closure Levels web page located at


On an annual basis, IDEM compares its risk-based screening levels against the most recent updates the U.S. EPA applies to its own regional levels. Changes to state and federal screening and closure levels can affect environmental liabilities for companies across Indiana with respect to how the primary risk driving chemicals, specific industries or ongoing site characterizations could be affected, positively or negatively. For 2020, the changes are relatively minor.

It is notable that updated Table A-6 includes the same list of chemicals shown in the 2019 Tables with the addition of new screening levels for the following 7 chemicals: bromoacetic acid, organic chloramines, dibromoacetic acid, dichloroamine, endosulfan sulfate, 2-ethyl-1-hexanol, and trichloroamine. Additionally, the name changes for nitrate, nitrite, uranium (soluble salts), and styrene-acrylonitrile (SAN) trimer have also been incorporated. The air screening level units for refractory ceramic fibers have been changed from fibers per cubic centimeter to fibers per cubic meter. It also reflects the inclusion of Maximum Residual Disinfectant Levels (MRDLs) as Maximum Contaminant Levels (MCLs) for chlorine and chlorine dioxide and the inclusion of the asbestos MCL.


The 2020 Table A-6 also incorporates toxicity updates from the U.S. EPA for the following 10 chemicals: auramine, 1,3-butadiene, formaldehyde, 4,4-methylene-bis(N,N-dimethyl)aniline, 2-nitropropane, Aroclor 1248, tert-butyl acetate, alpha,alpha,alpha,p-tetrachlorotoluene, methyl thiophanate, and 2,4,4-trimethylpentene.


IDEM is continuing to monitor the U.S. EPA as they develop screening levels for per and polyfluoroalkyl substances (PFAs). The U.S. EPA Screening Level Tables (and therefore, IDEM) currently contain entries for perfluorobutane sulfonic acid (PFBS), perfluorobutanesulfonate, and potassium perfluorobutane sulfonate.


As with prior changes, there is a 6-month transition period, which ends this year on September 2, 2020, per IDEM’s Remediation Closure Guide. Accordingly, 2019 screening levels remain applicable if a remediation or corrective action work plan is submitted by a responsible party during the transition period. After the transition period has ended, 2020 screening levels become enforced.

Wilcox Environmental Engineering continually monitors ever-changing regulations at both the state and federal levels. Prompt awareness permits us to analyze changes for our clients and thus maximize the benefits of positive change, or conversely, minimize the impact of negative changes to their specific environmental liabilities.