Ohio Groundwater Standards - Volatile Organic Compounds (VOCs)

Overview

Ohio’s Voluntary Action Program (VAP) establishes generic cleanup standards for groundwater under OAC 3745-300. The values below are Unrestricted Potable Use Standards (UPUS) - the default and most restrictive groundwater classification, which assumes groundwater is or could be used as a drinking water source.

The UPUS is the lower of the risk-based groundwater concentration and the Safe Drinking Water Act MCL. For most VOCs with MCLs, the MCL governs. For contaminants without MCLs (like MTBE), the risk-based value is the standard.

Other groundwater classifications: If groundwater at your site is classified as restricted potable use (RPUS) or non-potable (RNPUS) under OAC 3745-300-07, less restrictive standards may apply. See the VAP Program Overview for details on groundwater classification and Urban Setting Designations.

VOC Groundwater Standards

† Listed in CIDARS under Supplemental Criteria rather than as an Appendix A generic numerical standard.

Qualifier key:

• (b) MCL is for Total Trihalomethanes. The 80 µg/L value applies to the sum of the four trihalomethanes, not to each compound individually.

Practical Notes for Consultants

Sampling considerations: When collecting groundwater samples for VOC analysis, use 40 mL glass VOA vials with HCl preservative and zero headspace. Low-flow sampling is the standard method per Ohio EPA guidance - purge at <500 mL/min until field parameters stabilize.

Lab methods: Request EPA Method 8260 (or 8260C) for full VOC analysis. If you only need BTEX, some labs offer a cheaper BTEX-specific package, but 8260 gives you the full chlorinated solvent suite which is almost always worth having at Ohio sites.

Common pitfall: Vinyl chloride is frequently the risk driver at chlorinated solvent sites because its standard (2 µg/L) is tighter than TCE or PCE (both 5 µg/L), and it’s a degradation product that can persist in groundwater. Always include it in your analyte list even if the primary contaminant of concern is TCE or PCE.

BTEX vs. chlorinated solvents: At petroleum UST sites, BTEX compounds are typically the focus. At dry cleaner or industrial sites, the chlorinated solvent suite (TCE, PCE, DCE, vinyl chloride) is more relevant. Many Ohio sites have both - don’t assume one excludes the other.

When These Standards Apply

Ohio VAP generic standards apply to:

• Properties enrolled in the Ohio Voluntary Action Program
• Phase II ESA screening level comparisons (common practice even outside VAP)
• Remediation goal-setting when a property owner elects to use generic standards rather than site-specific risk assessment

They do not directly apply to:

• RCRA corrective action sites (which use separate OEPA guidance)
• Federal Superfund (CERCLA) sites (which use EPA RSLs or site-specific values)
• Drinking water compliance (which uses MCLs under the Safe Drinking Water Act)