Technical


The RST Technical Branch is staffed by engineers and geologists who provide technical and regulatory oversight for owner/operator-led corrective actions (cleanups) involving the release of petroleum products from underground storage tanks (USTs) and aboveground storage tanks (ASTs). When a regulated substance release is confirmed, tank owners or operators are required to have a site assessment performed to determine the level and extent of any contamination. Branch staff members make sure that the facility owners hire qualified professionals to do the job and document its progress.

The RST Technical Branch also provides direction and oversight for corrective action projects conducted by the division’s state-hired contractors on orphaned or abandoned storage tank sites.

Corrective Action at Facilities with USTs

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Regulatory guidance for initial response and abatement activities is found in 40 CFR 280.61 and 280.62. Briefly, upon discovery of a suspected release or confirmation of a release, in accordance with 40 CFR 280.52, the responsible party must:

  • Report the release by telephone or email to ADEQ within 24 hours of discovery.
  • Take immediate action to prevent any further release of the regulated substance to the environment.
  • Identify and mitigate fire, explosion, and vapor hazards.
  • Remedy hazards posed by contaminated soils or other wastes resulting from release confirmation, site investigation, hazard abatement, or corrective action activities.

While the regulatory citation applies only to USTs, these steps may also be required in the event of a release from a leaking AST if the corrective action is under the oversight of the RST Division.

Pre-approval of costs for initial response activities is not required for possible trust fund participation. The costs incurred, however, must be reasonable if they are to be submitted for reimbursement. An emergency should not be used as an excuse for failure to exercise common sense and prudence where costs are concerned.

Free product is defined in 40 CFR 280.12 as “a regulated substance that is present as a non-aqueous phase liquid [liquid not dissolved in water],” sometimes also called NAPL.

Although it is difficult to correlate an observed thickness of free product in a monitoring well to a defined risk to human health and the environment, free product recovery is required by 40 CFR 280.64 to the “maximum extent practicable” as determined by ADEQ.

If sufficient free product thicknesses are present on the groundwater table, the product itself may be mobile. Consequently, abatement of free product migration is a minimum objective in free product removal and another reason for free product recovery as an interim measure during site assessment activities or during development of a corrective action plan.

Guidance for investigating the presence of free product and implementing effective recovery measures is available in a document entitled "How to Effectively Recover Free Product at Leaking Underground Storage Tank Sites - A Guide for State Regulators"

Unless otherwise directed by ADEQ, an Initial Site Characterization (ISC) must be reported within 45 days of a confirmed release. This regulatory requirement and a description of compliance are found in 40 CFR 280.63.

The ISC is typically the decision point for RST Division technical staff to determine if no further work will be required in response to a release or if further investigation and/or remediation will be required.

In order for ADEQ to make this determination, three major questions must be answered by the ISC: Have wells (including monitoring wells) or other receptors been affected by the release? Is free product present in or on the uppermost groundwater unit beneath the site? Are nearby receptors potentially affected by the release?

In addition to supporting ADEQ decision-making, the ISC provides important prerequisite information for the owner/operator to design the next level of investigation. This is the most common problem area for ISC reports. It is easily possible for enough information to be presented for ADEQ to determine that further investigation is necessary but still not provide enough information to adequately devise and cost the investigation.

While the regulatory citation applies only to USTs, an ISC may be required in the event of a release from regulated ASTs as well, if the response is under the oversight of the RST Division.

If review of the Initial Site Characterization results in the determination by ADEQ that an environmentally significant release has occurred, an investigation to identify the location of soils affected by the release and the level and extent of dissolved product contamination in groundwater will be requested. This regulatory requirement and a description of compliance are found in 40 CFR 280.65.

The work described by this citation is complex and must be performed and reported in a manner that demonstrates technical adequacy by trained, experienced people. It falls under Arkansas professional practice statutes, which have been interpreted to require the services of a professional engineer or geologist licensed to practice in Arkansas to seal site assessment reports. (Memo from Arkansas Board for Professional Geologists on Geologic Interpretation and Analysis) While the regulatory citation applies only to USTs, an investigation for soil and groundwater cleanup may be required in the event of a release from regulated ASTs as well, if the response is under the oversight of the RST Division.

Beyond the non-degradation legislation that chartered ADEQ, Arkansas does not have a specific groundwater quality law or regulation. Consequently, each program dealing with groundwater has generic corrective action goals that are rooted in the federal law or regulation from which the program is delegated. For the RST Division, there are two program goals:

  • Protection of human health and the environment from regulated substance exposures (40 CFR 280.66)
  • Free product removal “to the maximum extent practicable” to prevent the spread of regulated substance contamination (40 CFR 280.64)

Each release response will be managed on a site-specific basis, within the two program goals outlined above. When sufficient site and risk investigation data becomes available, the Technical Branch staff will draft an exposure assessment that will summarize what is known about the release, identify pertinent exposures, and establish preliminary remediation goals. A Corrective Action Plan will then be ordered if remediation is justified.

  • Goals to address human health exposures will be established using the ASTM E1739-95 standard. Points of compliance will be assigned by ADEQ based on the relationship to the affected receptors.
  • For ecological exposures, the National Ambient Water Quality Criteria will be used for groundwater underflow to waters of the state. Points of compliance will be assigned by ADEQ based on the relationship to the affected receptors.
  • For groundwater contamination source controls, a groundwater goal equal to the NAPL equilibrium concentration and incorporating a dilution attenuation factor of 10 to account for sampling uncertainties will be specified. Points of compliance will be throughout the contaminated zone.

As a part of the corrective action process, division staff may, after review of the Initial Site Characterization and the circumstances of the release, request further assessment of the site for the purposes of defining the risk or establishing the design of a remediation program. Authority to request further assessment and regulatory guidance for investigations for soil and groundwater clean-up are found in 40 CFR 280.65.

  • The Site Assessment Report will be requested in writing by ADEQ, according to the conditions of 280.65.
  • Specific guidance regarding the goals of the investigation, the content and format of the report, and the schedule for compliance will be provided at the time the SAR is requested.
  • To ensure that the goals are met and that the investigation methods are appropriate to the site, a work plan will be reviewed and approved by the technical staff before the work is undertaken.

The work described by this section is demanding and must be performed and reported by persons with specific education and experience, in a manner which demonstrates technical competency. It falls under professional practice statutes that have been interpreted to require the services of a professional geologist licensed to practice in Arkansas to seal site assessment reports.

While the regulatory citation applies only to USTs, the SAR may also be required in the event of a release from a leaking aboveground storage tank if it is under the oversight of the RST Division.

At any time during the corrective action process, the RST Division staff may require a plan for responding to soil and groundwater contamination or other attenuation of public health or environmental hazards. The authority to request Corrective Action Plans and regulatory guidance for their development and implementation is found in 40 CFR 280.66.

All Corrective Action Plans must address the following elements in detail:

  • A discussion of the background of the case, including a chronology of the events leading up to the development of the Corrective Action Plan. Information must be provided about how the release was detected, the nature and estimated quantity of the released regulated substance(s), and a summary of response actions taken to date.
  • A conceptual site model to summarize what is known about the geology and hydro-geology of the site, physical site conditions, contaminant sources and distributions, exposure pathways and migration routes, and affected or potentially-affected receptors.
  • A coherent strategy for adequately protecting human health, safety, and the environment, with objective, media-specific goals and points of compliance for each goal.
  • A list of the actions required to meet the goals of the Corrective Action Plan, including any contingency actions, and a proposed schedule for their accomplishment.
  • If the facility is eligible to participate in the Arkansas Petroleum Storage Tank Trust Fund, an estimate of the costs for each task must be included.
  • A program for monitoring, evaluating, and reporting progress toward meeting the goals of the Corrective Action Plan.
  • A plan for notifying stakeholders of the existence of the Corrective Action Plan, according to the provisions of 40 CFR 280.67. Specific notice and a copy of the Corrective Action Plan must be provided to those stakeholders directly affected, and general notice must be provided to the public in the area of the release.

While the regulatory citation applies only to USTs, a Corrective Action Plan may also be required in the event of a release from regulated ASTs if the response is under the oversight of the RST Division.

Corrective Action at Facilities with ASTs

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Corrective actions for certain sizes and types of aboveground storage tanks (ASTs) are also under the oversight of the RST Division and may be eligible for Arkansas Petroleum Storage Tank Trust Fund participation. These tanks are defined as holding liquid petroleum motor fuels and ranging in size from 1,320 to 40,000 U.S. gallons in capacity.

The technical standards for AST storage and operations are found in the Arkansas Fire Prevention Code, 2014 Edition. This set of regulations is enforced through the Arkansas State Fire Marshal’s Office. Any questions concerning those requirements should be directed to the Arkansas State Fire Marshal at 501-618-8624. Spill Prevention Control and Countermeasures (SPCC) plans may also be required for AST facilities. This federal EPA program is not delegated to ADEQ, and all questions about SPCC plans should be directed to EPA Region VI at 214-665-6702.

Oversight of any required response to a leak from a regulated AST will be provided by the RST Division, according to the policies and procedures established by the division.

Because of staff and contractor familiarity with the corrective action process found in 40 CFR 280, that model will be used for all AST corrective actions, including the requirement for public participation. Trust fund participation, if the AST is eligible, will likewise be on the same basis as for a UST release.