Overview

These are the Ohio BUSTR closure assessment action levels from Table 2.2 of the 2017 Technical Guidance Manual. These values are used when evaluating soil and groundwater samples collected during UST closures - permanent removals, closures-in-place, out-of-service assessments, and changes-in-service.

If all analytical results are below the applicable closure action levels, BUSTR issues a No Further Action (NFA) letter. If any result exceeds an action level, the site enters the corrective action process under OAC 1301:7-9-13.

Closure Action Levels - All Chemicals

Showing 19 of 19 chemicals

Chemical	CAS Number	Class 1 Soil (mg/kg)	Class 2 Soil (mg/kg)	Class 3 Soil (mg/kg)	Groundwater (mg/L)
Benzene	71-43-2	0.246	0.437	1.63	0.005
Toluene	108-88-3	70.7	168	850	1
Ethylbenzene	100-41-4	84.5	130	130	0.7
Total Xylenes	1330-20-7	42.7	51.8	63.5	10
Naphthalene	91-20-3	0.511	1.12	4.99	0.0014
1,2,4-Trimethylbenzene	95-63-6	2.37	5.89	7.99	0.015
MTBE	1634-04-4	1.58	2.67	11.5	0.12
1,2-Dibromoethane (EDB)	106-93-4	0.000982	0.00177	0.00734	0.00005
1,2-Dichloroethane (EDC)	107-06-2	0.101	0.177	0.714	0.005
Benzo(a)anthracene	56-55-3	12	12	12	0.00092
Benzo(a)pyrene	50-32-8	1.2	1.2	1.2	0.0002
Benzo(b)fluoranthene	205-99-2	12	12	12	0.00092
Benzo(k)fluoranthene	207-08-9	120	120	120	0.0092
Chrysene	218-01-9	1,200	1,200	1,200	0.092
Dibenz(a,h)anthracene	53-70-3	1.2	1.2	1.2	0.000092
Indeno(1,2,3-cd)pyrene	193-39-5	12	12	12	0.00092
TPH C6-C12	NL	1,000	5,000	8,000	NL
TPH C10-C20	NL	2,000	10,000	20,000	NL
TPH C20-C34	NL	5,000	20,000	40,000	NL

Default Assumptions

The closure action levels are based on the most conservative set of assumptions:

Land use: Residential
Groundwater: Assumed to be a drinking water source
Depth to groundwater: Less than 15 feet
Soil class: Class 1 (default - the most restrictive)

These assumptions can only be changed during the corrective action process (not during closure assessment). During closure, you use Class 1 unless you submit geotechnical documentation confirming a different soil class.

Soil Classes

BUSTR classifies soils into three classes based on grain size distribution:

Class 1 - Fine-grained soils (clays, silts) and bedrock. This is the default and most conservative classification. Most Ohio glacial till falls into Class 1.

Class 2 - Medium-grained soils (silty sands, sandy silts). Requires geotechnical analysis (grain size distribution) to confirm.

Class 3 - Coarse-grained soils (clean sands, gravels). Requires geotechnical analysis to confirm. Has the highest (least restrictive) action levels.

The logic: contaminants are less mobile in coarser soils because they partition more strongly to the soil phase and are less likely to leach to groundwater. This is the opposite of what you might intuitively expect - coarser soils have higher action levels because the leaching pathway is less of a concern due to faster drainage and lower capillary rise.

Key Compounds to Watch

Benzene

The Class 1 soil closure action level for benzene is 0.246 mg/kg - one of the most restrictive values in the table. This is significantly lower than the VAP residential soil GDCSS for benzene (1,100 mg/kg) because the BUSTR value is driven by the soil-to-groundwater leaching pathway, not direct contact.

At petroleum UST sites, benzene in soil is almost always the risk driver for the closure assessment. If benzene passes, the other BTEX compounds almost always pass too.

Naphthalene

The closure action level for naphthalene in Class 1 soil is 0.511 mg/kg and in groundwater is 0.0014 mg/L (1.4 µg/L). Naphthalene is the most restrictive compound after benzene for many petroleum sites, particularly diesel and fuel oil releases where naphthalene concentrations can be significant.

EDB and EDC

1,2-Dibromoethane (EDB) and 1,2-Dichloroethane (EDC) are lead scavengers that were added to leaded gasoline. They are only relevant at sites where leaded gasoline was stored (generally USTs in service before the mid-1980s). The action levels are extremely low - EDB in Class 1 soil is 0.000982 mg/kg (less than 1 part per billion). Confirm with your laboratory that their detection limits can achieve these levels.

Carcinogenic PAHs

The PAH closure action levels are based on direct contact exposure. Benzo(a)pyrene has the most restrictive soil action level at 1.2 mg/kg across all soil classes. PAHs are primarily a concern at sites with heavier petroleum products (diesel, fuel oil, used oil) rather than gasoline.

Note that the PAH soil action levels do not change between soil classes - they are based on direct contact, not leaching, so soil permeability doesn’t affect the standard.

TPH

TPH action levels are reported by carbon fraction:

C6-C12 (light distillates): 1,000 mg/kg (Class 1) to 8,000 mg/kg (Class 3)
C10-C20 (middle distillates): 2,000 mg/kg (Class 1) to 20,000 mg/kg (Class 3)
C20-C34 (heavy distillates): 5,000 mg/kg (Class 1) to 40,000 mg/kg (Class 3)

There are no groundwater action levels for TPH in the closure assessment. TPH in groundwater is evaluated during the corrective action process.

Practical Notes

Always assume Class 1 during closure unless you have geotechnical data already in hand. Don’t plan a closure assuming Class 2 or 3 soil - if the geotechnical results come back as Class 1, you’ve compared against the wrong standards.
Groundwater sampling is required if water recharges the excavation within 24 hours of dewatering. If no water recharges within 24 hours, only soil sampling is required.
Closure results must be submitted to BUSTR within 90 days of sample collection on the appropriate closure form.
EDB and EDC are only required for Analytical Group 1 (gasoline) USTs. If the UST stored diesel or fuel oil only, these compounds are not required.
Used oil USTs may contain both petroleum and hazardous substances and require analysis for all analytical groups.

BUSTR Corrective Action Standards - Full corrective action tables by pathway
BUSTR Program Overview - How the closure process fits into the overall program
Ohio VAP Soil Standards - VOCs - For comparison with VAP standards
Ohio VAP Program Overview - Understanding the difference between BUSTR and VAP