BUSTR Interim Response Actions - Source Removal and Short-Term Cleanup

Overview

An Interim Response Action (IRA) is a short-term cleanup action conducted at a BUSTR petroleum UST site to remove contaminated source material or reduce COC concentrations. IRAs are one of the most common and practical tools available to consultants working BUSTR corrective action sites because they can significantly reduce contaminant mass and potentially eliminate the need for more complex and expensive long-term remediation.

IRAs are authorized under OAC 1301:7-9-13(K) and are distinct from Remedial Action Plans (RAPs). Where a RAP involves engineered remediation systems, monitoring plans, and public notice, an IRA is intended to be a quicker, more targeted action.

When to Conduct an IRA

An IRA may be conducted after any tier evaluation is approved by BUSTR and COC concentrations remain above applicable action levels or site-specific target levels (SSTLs). Specifically, an IRA can be implemented within 90 days of BUSTR approval of:

A Tier 1 Investigation report
A Tier 2 Evaluation report
A Tier 3 Evaluation report

IRAs are most commonly used after Tier 1 when the source area is well-defined and physically accessible. The goal is usually to remove the most contaminated soil, reduce dissolved-phase concentrations in groundwater, and simplify the pathway analysis for subsequent tier evaluations.

What Qualifies as an IRA

IRAs are limited to source removal or short-term actions not exceeding three months. Examples include:

Soil excavation (over-excavation) - removing contaminated soil from the source area to reduce mass and concentrations
Enhanced fluid recovery (EFR) - accelerated pumping to remove dissolved-phase contamination or free product
Pump-and-treat - short-term groundwater extraction and treatment
Free product recovery - targeted recovery of LNAPL beyond the ongoing monthly FPR program

What does NOT qualify as an IRA:

Injection of chemicals, surfactants, or substances to increase biological activity or chemically degrade COCs in the subsurface. These activities require a Remedial Action Plan.
Any action expected to take longer than three months
Any action involving more than 800 cubic yards of soil without prior BUSTR approval

Limits and Pre-Approval Requirements

Standard IRA (No Pre-Approval Required)

An IRA can proceed without prior BUSTR approval if all of the following are true:

Total soil excavation volume is 800 cubic yards or less
Anticipated duration is three months or less
This is the first IRA for the site (across all tier evaluations)

Pre-Approval Required

BUSTR approval must be obtained before starting the IRA if any of the following apply:

Combined total soil excavation volume will exceed 800 cubic yards
Combined anticipated time to complete the IRA exceeds three months
More than one IRA will be conducted across all tier evaluations at the site

If the volume unexpectedly exceeds 800 cubic yards during excavation, contact the State Fire Marshal immediately for approval to continue.

The pre-approval request must include:

Description of activities to be conducted
Site map identifying the limits of soil excavation (if applicable)
Estimation of soil and groundwater volumes to be managed
Estimation of anticipated time to completion
Confirmatory sampling plan
Comparison of the selected IRA technology to other corrective action options, including cost evaluation

Notification

An IRA Notification Form 2022 must be submitted to BUSTR at least 10 days before beginning the IRA. All necessary permits must be secured before starting work.

Confirmatory Sampling

After completing an IRA, confirmatory samples must be collected to determine the concentration of COCs remaining in the soil or groundwater.

Soil Confirmatory Sampling

Collect soil samples from the excavation sidewalls and bottom using a ratio of one sample per 100 square feet. A minimum of one soil sample must be collected from each sidewall and from the bottom of the excavation. Bias samples toward areas with the highest contamination.

Lab submission requirements depend on excavation volume:

Less than 400 cubic yards: A minimum of five samples must be submitted to the lab (one per wall plus one from the bottom). Select the five samples with the highest field screening results.
Greater than 400 cubic yards: A minimum of ten samples must be submitted to the lab (two per wall plus two from the bottom). Select the ten samples with the highest field screening results.

Contaminated soils removed during the IRA that previously exceeded action levels or SSTLs must be sent to a landfill for disposal or treatment. Handle all excavated material according to the PCS rules (OAC 1301:7-9-16 and 17).

Groundwater Confirmatory Sampling

If the IRA addressed localized groundwater contamination, develop a groundwater sampling program to demonstrate effectiveness. This may require re-installing monitoring wells destroyed during excavation.

At a minimum:

Collect a groundwater sample from each monitoring well within the affected area
Conduct at least two quarters of confirmatory groundwater sampling in the previously contaminated area
BUSTR may require additional confirmatory sampling

Results Evaluation

All COC concentrations remaining in soil and groundwater must be at or below the applicable action levels or SSTLs to receive NFA status. If concentrations remain above the targets after the IRA, additional corrective action is required (another tier evaluation, a RAP, or in some cases another IRA with BUSTR pre-approval).

Reporting

Submit a completed Interim Response Action Form 2022 within 60 days of completing the IRA activities.

Practical Considerations

IRAs are often the most cost-effective path to NFA. If the source area is well-defined and the contamination is concentrated in a relatively small volume of soil, excavation during an IRA can eliminate the need for Tier 2 evaluation, long-term monitoring, and engineered remediation. The cost of mobilizing an excavator and disposing of a few hundred cubic yards of soil is often less than the cost of a full Tier 2 evaluation with BUSTR-Screen modeling.

Know the volume before you dig. The 800 cubic yard threshold matters. Exceeding it without pre-approval creates a compliance issue. Estimate the excavation volume carefully during planning and build in margin. If the contamination extent is uncertain, discuss with BUSTR before mobilizing.

Confirmatory sampling drives the outcome. The IRA is only as good as the confirmatory results. If sidewall or bottom samples still exceed action levels, the IRA did not achieve its objective and additional work is required. Bias your confirmatory samples toward the areas most likely to still be contaminated - not the cleanest walls.

Coordinate with PCS management. The soil you excavate during an IRA is subject to the same PCS rules as closure excavation material. Plan stockpile locations, sampling, and disposal logistics before breaking ground.

Source

BUSTR Technical Guidance Manual (TGM) 2022, Chapter 3: Corrective Action Requirements (Section 3.10). OAC 1301:7-9-13(K).