indianaidemexcavationscreening-levelssoilbenzene

IDEM Excavation Screening Levels - The Benzene Example

Benzene has no residential or commercial direct-contact soil Published Level in Indiana, but it has an excavation screening level of 2,000 mg/kg. A consultant who reads the blank direct-contact cell as “no standard” misses a value that governs worker protection during soil handling, and one who reads it as zero flags a site that may need no soil action at all. Both errors cost time on Indiana projects.

Why Blank Cells Appear in the Soil Tables

Indiana’s Published Levels come from the IDEM (Indiana Department of Environmental Management) Risk-based Closure Guide, WASTE-0046-R2, a guidance document that applies across the state’s cleanup programs including the Voluntary Remediation Program, State Cleanup Program, LUST, and RCRA corrective action. The current tables are effective March 28, 2025 and use a target cancer risk of 0.00001 and a hazard quotient of 1.0.

Long-term direct-contact values assume years of repeated exposure to soil. Many VOCs (Volatile Organic Compounds) are too volatile to support that calculation, so they carry no residential or commercial/industrial soil value. They still pose short-term inhalation and dermal risks to workers actively digging in contaminated soil, which is why the excavation table covers 853 chemicals - the most complete soil table in the Indiana framework. A blank cell means no published level exists for that pathway. It never means zero.

Benzene as the Worked Example

Benzene (CAS 71-43-2) shows the pattern cleanly. The residential and commercial/industrial direct-contact columns are blank. The excavation table lists 2,000 mg/kg with an S qualifier, meaning the value is capped at soil saturation - the maximum concentration soil can hold before a separate liquid phase forms. The S-qualified number is a physical ceiling, not a risk calculation.

Benzene risk at Indiana sites is instead driven by other pathways. The groundwater Published Level is 5 ug/L, matching the federal MCL (Maximum Contaminant Level), and IDEM does not publish soil migration-to-groundwater screening levels - that pathway is evaluated site-specifically under the R2. What this means in practice: a benzene soil hit below 2,000 mg/kg can still be a serious groundwater or vapor problem, and the excavation value tells you nothing about closure.

Ohio note: Ohio’s CIDARS (Chemical Information Database and Applicable Regulatory Standards) does not publish a separate excavation screening level table. This is an Indiana-specific feature of the IDEM published levels framework. Ohio is not without a functional analog, though: the VAP generic standards in CIDARS include a construction worker soil category serving the short-term worker-exposure function - a separate land-use column within the direct-contact standards, not a standalone excavation table.

Using the Excavation Table Correctly

Appropriate uses:

  • Worker protection: Evaluating short-term exposure for construction and excavation workers contacting contaminated soil.
  • Stockpile management: Setting thresholds for on-site handling and stockpiling during remedial excavation.
  • Brownfield redevelopment: Assessing construction worker exposure during site work.

Not appropriate:

  • Closure decisions: Excavation levels are not cleanup standards and do not determine whether a site has met closure requirements for any land use.
  • Leaching evaluation: The groundwater pathway is assessed separately and site-specifically under the R2.
  • Replacing HAZWOPER: Excavating contaminated soil may independently trigger OSHA requirements under 29 CFR 1910.120, including air monitoring, PPE, and training.

Check the current excavation table for the value and qualifier before mobilizing to any Indiana dig. For the full 853-chemical table and qualifier definitions, see our Indiana standards pages, and the IDEM R2 walkthrough covers how the tables fit into the closure framework.