IDEM R2 Soil Published Levels - Indiana VOCs (Residential and C/I)

Overview

These are Indiana’s Published Level Table 1 soil direct-contact standards for volatile organic compounds (VOCs), from the IDEM Risk-based Closure Guide (WASTE-0046-R2, “the R2”), effective March 28, 2025. IDEM renamed these values from “Screening Levels” to “Published Levels” in the 2022 R2 update - the terminology has changed but the regulatory function is the same.

Risk basis: Indiana’s published levels are derived at a 1E-05 cancer risk (1 in 100,000) and a hazard quotient (HQ) of 1.0. This is 10 times less conservative than EPA’s default 1E-06 risk level. For carcinogens, Indiana’s screening levels are approximately 10 times higher (less protective) than default EPA Regional Screening Levels. This difference matters when comparing Indiana results to federal Superfund guidance.

Qualifier key:

• C = Carcinogenic - value is cancer risk-based
• N = Noncarcinogenic - value is hazard quotient-based
• S = Soil saturation cap - value is the maximum concentration soil can hold before a separate phase forms
• L = 100,000 mg/kg cap - value is capped at the practical maximum
• D = Detection limit-based
• M = Based on the Maximum Contaminant Level (MCL)

Blank cells indicate no published level for that chemical and pathway combination - not a level of zero.

VOC note: Many VOCs have no long-term soil direct-contact values because they volatilize before causing direct-contact risk. For short-term worker exposure during excavation, see Indiana’s Excavation Screening Levels, which cover nearly all VOCs that lack long-term soil values.

Soil Direct-Contact Published Levels - VOCs

Both residential and commercial/industrial (C/I) values are shown. Residential standards apply to properties where the residential receptor is the exposure target (homes, schools, parks). C/I standards apply where the adult worker is the primary receptor.

Practical Notes

Vapor intrusion is often the controlling pathway for VOCs. The soil direct-contact values above may be more permissive than soil-to-indoor-air pathway values. A complete Indiana IDEM site assessment evaluates soil direct contact, groundwater, indoor air, and soil gas separately. Do not assume that meeting a soil direct-contact published level means the vapor intrusion pathway is also satisfied.

BTEX compounds (benzene, toluene, ethylbenzene, xylenes) are the primary VOC concerns at petroleum UST sites. Benzene typically drives risk at the lowest concentrations. Check the Indiana Groundwater Published Levels page for groundwater screening at the same site.

Chlorinated solvents (TCE, PCE, vinyl chloride) are common at dry cleaner and industrial sites. Vinyl chloride - a TCE and PCE degradation product - often has the most stringent standards. Always include it in your analyte list at chlorinated solvent sites even if TCE or PCE is the primary source contaminant.

Comparing to Ohio: Ohio’s VAP generic direct-contact standards (OAC 3745-300-08) are derived at the same 1E-05 cancer risk target as Indiana’s published levels. The two states’ values still differ chemical by chemical because of different exposure assumptions and toxicity inputs, so on a multi-state project compare each result to the correct state’s table rather than assuming the values are interchangeable.

Comparing to EPA RSLs: EPA publishes Regional Screening Levels at a default 1E-06 cancer risk. Indiana’s 1E-05 values will generally be higher (less conservative) than EPA RSLs for carcinogens. For non-carcinogens, the comparison depends on the specific exposure assumptions used.