Ohio BUSTR Corrective Action Standards
BUSTR corrective action levels for petroleum UST sites in Ohio. Delineation, groundwater, direct contact, and TPH by pathway.
Overview
These are the Ohio BUSTR corrective action levels from Tables 3.3 through 3.9 of the 2017 Technical Guidance Manual. These values apply when a petroleum release from a regulated UST has been confirmed and the site is undergoing corrective action under OAC 1301:7-9-13.
Unlike closure action levels (which assume worst-case conditions), corrective action levels are pathway-specific and can be adjusted based on actual site conditions - soil class, depth to groundwater, land use, and whether groundwater is a drinking water source.
How Corrective Action Levels Work
The corrective action process requires comparing the highest detected concentration of each COC against the action levels for every applicable pathway. The most restrictive pathway drives the cleanup - not just one table, but the lowest value across all applicable tables.
The applicable pathways depend on three key site conditions:
- Is groundwater a drinking water source? - If yes, the groundwater ingestion pathway and soil-to-drinking-water leaching pathway apply
- What is the depth to groundwater? - Affects vapor intrusion (indoor air) action levels
- What is the land use? - Residential vs. non-residential affects direct contact and vapor intrusion levels
Delineation Levels (Table 3.3)
Before comparing to action levels, contamination must be delineated - you need to define the horizontal and vertical extent of the plume. Delineation levels tell you when you’ve reached the edge of the contamination.
| Chemical | Soil (mg/kg) | Groundwater (mg/L) |
|---|---|---|
| Benzene | 1.67 | 0.417 |
| Toluene | 1,240 | 217 |
| Ethylbenzene | 406 | 41.6 |
| Total Xylenes | 42.7 | 10 |
| Naphthalene | 52.7 | 1.68 |
| 1,2,4-Trimethylbenzene | 5.35 | 0.417 |
| MTBE | 150 | 134 |
| EDB | 0.154 | 0.09 |
| EDC | 1.01 | 0.59 |
| Benzo(a)pyrene | 1.2 | 18.3 |
Delineation continues outward from the source until all COC concentrations are below the delineation levels. BUSTR may also request delineation of additional COCs not listed in Table 3.3 (including TPH).
Groundwater Ingestion Action Levels (Table 3.4)
These apply when groundwater is classified as a drinking water source. They represent the concentration in groundwater that is protective of human health through the drinking water ingestion pathway.
| Chemical | Action Level (mg/L) |
|---|---|
| Benzene | 0.005 |
| Toluene | 1 |
| Ethylbenzene | 0.7 |
| Total Xylenes | 10 |
| Naphthalene | 0.0014 |
| 1,2,4-Trimethylbenzene | 0.015 |
| MTBE | 0.12 |
| EDB | 0.00005 |
| EDC | 0.005 |
| Benzo(a)anthracene | 0.00092 |
| Benzo(a)pyrene | 0.0002 |
| Benzo(b)fluoranthene | 0.00092 |
| Benzo(k)fluoranthene | 0.0092 |
| Chrysene | 0.092 |
| Dibenz(a,h)anthracene | 0.000092 |
| Indeno(1,2,3-cd)pyrene | 0.00092 |
Note: Benzene (0.005 mg/L = 5 µg/L) matches the federal MCL. Many of the PAH values are extremely low - confirm your laboratory can achieve the required detection limits.
Groundwater to Indoor Air Action Levels (Table 3.5)
These vary by soil class, depth to groundwater, and land use (residential vs. non-residential). The table below shows Class 1 soil, less than 15 feet to groundwater - the most common scenario.
Class 1 Soil, < 15 ft to Groundwater
| Chemical | Residential (mg/L) | Non-Residential (mg/L) |
|---|---|---|
| Benzene | 4.17 | 26.1 |
| Toluene | 2,170 | 35,200 |
| Ethylbenzene | 416 | 6,760 |
| Total Xylenes | 50.7 | 822 |
| Naphthalene | 16.8 | 105 |
| 1,2,4-Trimethylbenzene | 4.17 | 67.6 |
| MTBE | 1,340 | 8,360 |
| EDB | 0.908 | 5.68 |
| EDC | 5.90 | 36.9 |
The full Table 3.5 in the TGM includes values for all four depth ranges (< 15 ft, 15-30 ft, 31-50 ft, > 50 ft) and all three soil classes. Values increase slightly with greater depth to groundwater because there is more vadose zone for attenuation.
For most petroleum UST sites with shallow groundwater (< 15 ft), the groundwater ingestion pathway (Table 3.4) will be more restrictive than the vapor intrusion pathway (Table 3.5). The vapor intrusion pathway becomes the driver at sites with non-drinking water groundwater.
Direct Contact Action Levels (Table 3.7)
These are the soil concentrations protective of human health through direct contact (ingestion, dermal, and particulate inhalation).
| Chemical | Residential (mg/kg) | Non-Residential (mg/kg) | Excavation Worker (mg/kg) |
|---|---|---|---|
| Benzene | 26 | 140 | 1,200 |
| Toluene | 820 | 820 | 820 |
| Ethylbenzene | 130 | 480 | 480 |
| Total Xylenes | 260 | 260 | 260 |
| Naphthalene | 90 | 450 | 560 |
| 1,2,4-Trimethylbenzene | 160 | 220 | 220 |
| MTBE | 1,100 | 5,700 | 8,900 |
| EDB | 0.83 | 4.4 | 38 |
| EDC | 11 | 56 | 480 |
| Benzo(a)anthracene | 12 | 58 | 1,200 |
| Benzo(a)pyrene | 1.2 | 5.8 | 120 |
| Benzo(b)fluoranthene | 12 | 58 | 1,200 |
| Benzo(k)fluoranthene | 120 | 580 | 12,000 |
| Chrysene | 1,200 | 5,800 | 120,000 |
| Dibenz(a,h)anthracene | 1.2 | 5.8 | 120 |
| Indeno(1,2,3-cd)pyrene | 12 | 58 | 1,200 |
Direct contact action levels do not vary by soil class or depth to groundwater - they are based solely on human exposure assumptions for each land use scenario.
TPH Action Levels (Table 3.8)
| Petroleum Fraction | Class 1 (mg/kg) | Class 2 (mg/kg) | Class 3 (mg/kg) |
|---|---|---|---|
| Light Distillates (C6-C12) | 1,000 | 5,000 | 8,000 |
| Middle Distillates (C10-C20) | 2,000 | 10,000 | 20,000 |
| Heavy Distillates (C20-C34) | 5,000 | 20,000 | 40,000 |
TPH action levels apply to soil only and must be evaluated in addition to individual COC action levels. A site can have individual BTEX concentrations below all action levels but still exceed TPH action levels - this is common at sites with heavy petroleum contamination where the bulk of the TPH consists of unresolved hydrocarbons that aren’t captured by the individual COC analysis.
Soil to Indoor Air, Drinking Water Leaching, and Non-Drinking Water Leaching (Table 3.9)
Table 3.9 contains soil action levels for three additional pathways. These vary by soil class and land use. The soil-to-drinking-water-leaching values are often the most restrictive soil action levels at a petroleum site, particularly for benzene.
For Class 1 soil, the soil-to-drinking-water-leaching action level for benzene is 0.246 mg/kg - the same value used as the closure action level. This pathway frequently drives the cleanup at sites where groundwater is classified as drinking water.
Practical Notes
- The most restrictive pathway wins. When evaluating a site, you must compare against every applicable pathway. The cleanup target for each COC is the lowest action level across all applicable pathways.
- Benzene in soil is almost always driven by the leaching pathway, not direct contact. The Class 1 soil leaching action level (0.246 mg/kg) is orders of magnitude lower than the residential direct contact level (26 mg/kg).
- Groundwater ingestion drives PAH cleanup when the drinking water pathway applies. The PAH groundwater ingestion values (Table 3.4) are extremely low - BaP at 0.0002 mg/L requires very sensitive analytical methods.
- TPH exceedances are common even when individual BTEX compounds are below action levels. Always analyze for TPH by carbon fraction in addition to individual COCs.
- The BUSTR-Screen spreadsheet can be used to develop site-specific (Tier 2) action levels when Tier 1 levels are exceeded. This tool is available from BUSTR and allows modification of default parameters based on actual site conditions.
- Document everything. BUSTR reviews corrective action reports closely. Include your pathway determination rationale, groundwater classification justification, soil class documentation, and all supporting data.
Related Standards
- BUSTR Closure Action Levels - Screening levels for UST closure assessments
- BUSTR Program Overview - How corrective action fits into the overall program
- Ohio VAP Groundwater Standards - VOCs - For comparison with VAP standards
- Ohio VAP Soil Standards - VOCs - For comparison with VAP standards
- Ohio Vapor Intrusion Evaluation Guide - VI evaluation under VAP/DERR programs
BUSTR corrective action levels - delineation levels, groundwater ingestion, direct contact, and TPH. Source: 2017 BUSTR TGM Tables 3.3-3.8.