Ohio VAP Groundwater Standards - SVOCs and PAHs

Overview

These are the Ohio VAP unrestricted potable use standards (UPUS) for semi-volatile organic compounds (SVOCs) and polycyclic aromatic hydrocarbons (PAHs) in groundwater from the CIDARS database, effective February 16, 2025.

The UPUS is the lower of the risk-based groundwater concentration and the federal Safe Drinking Water Act MCL (where one exists). For most SVOCs, there is no MCL - the UPUS equals the risk-based value. The UPUS applies when groundwater at the site is classified as potable use under OAC 3745-300-07.

Unrestricted Potable Use Standards - SVOCs and PAHs

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

Key Compounds

Benzo[a]pyrene

The UPUS is 0.2 µg/L - the federal MCL. BaP is the only individual PAH with an MCL. Most other PAHs have risk-based UPUS values that are higher, but dibenz[a,h]anthracene (0.25 µg/L) and benz[a]anthracene (0.30 µg/L) are comparable.

1-Methylnaphthalene

The UPUS of 0.0063 µg/L (6.3 ppt) is extraordinarily low - lower than most PFAS standards. This compound is common at petroleum sites. Achieving this detection limit requires EPA Method 8270 SIM or equivalent low-level methods. Discuss detection limit requirements with your laboratory before sampling.

TCDD (2,3,7,8-Dioxin)

The UPUS of 0.00003 µg/L (30 parts per quadrillion) is the lowest standard in CIDARS. Dioxin analysis in water requires EPA Method 1613 with specialized low-level detection capabilities. Not all laboratories can achieve this reporting limit.

Bis(2-ethylhexyl)phthalate (DEHP)

The UPUS is 6 µg/L - the federal MCL. DEHP is a common laboratory and field contaminant from plastic tubing and sample containers. Always use glass sample containers and PTFE-lined caps for DEHP analysis. Elevated DEHP in groundwater should be evaluated against equipment blanks before concluding it represents site contamination.

Practical Notes

• Most SVOCs have limited groundwater mobility. PAHs in particular are hydrophobic and tend to adsorb to soil organic matter rather than dissolve in groundwater. When SVOCs are detected in groundwater, it often indicates a nearby source area with high concentrations or the presence of NAPL.
• Detection limits are critical. Several compounds on this list have UPUS values in the low parts-per-trillion range. Confirm with your laboratory that their reporting limits are below the applicable UPUS before submitting samples.
• DEHP contamination from sampling equipment is one of the most common false-positive issues in groundwater sampling. Use dedicated HDPE or stainless steel equipment and glass sample containers.
• PAHs in groundwater are most commonly associated with manufactured gas plant sites, creosote-treated wood facilities, and sites with coal tar or heavy petroleum contamination. Light petroleum releases (gasoline) typically don’t produce PAH groundwater contamination except for naphthalene.