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What Are the Site Assessment Requirements for an Underground Storage Tank System?

September 22, 2022

An underground storage tank (UST) system, which consists of a UST and the associated dispenser(s) and piping run(s), is defined as when 10% or more of the UST and associated piping volume is located below the ground surface. Whenever a regulated UST system is upgraded or removed, it is important for the owner/operator (O/O) or contractor to understand the following: when is an environmental site assessment required, what are the benefits to proper planning before the upgrades are implemented, and what steps should be taken to prepare for a site assessment. As the auto industry pivots to electric vehicles, site assessments should also be considered when petroleum fueling systems are exchanged for electronic charging stations. The following serves to answer commonly asked questions regarding a site assessment for a UST system.

Is a site assessment regulated?

Yes. UST site assessments are regulated by the Michigan Department of Licensing and Regulatory Affairs (LARA) – Storage Tank Division under Part 211, Underground Storage Tank Regulations, of Act 451 of 1994, as amended.

If upgrades will only be made to the dispensers, not the existing UST, is a site assessment required? What about if upgrades are being made at a site with a previous release?

The need for site assessment sampling beneath a dispenser and the associated piping depends on the situation. If more than 50% of the existing dispenser containment sump and/or underlying piping run is removed or closed in-place during an upgrade, then site assessment sampling is required. If upgrades are only made to dispenser components above the sump or if less than 50% of the sump and piping run will be replaced or repaired, then site assessment sampling is not required. A site assessment is always required when a UST is removed or closed in-place.

A site with a previous release (closed or open) is not precluded from site assessment requirements, as the data may identify a subsequent release(s) from the same point of origin or a separate release that occurred elsewhere in the UST system. In certain situations, site assessment data may be reflective of a known release that does not warrant reporting as a separate release; however, this determination is made by LARA on a case-by-case basis, depending on the lines of evidence from the site assessment. If a site assessment is to be conducted in the vicinity of a known release, it is recommended that an environmental Qualified Consultant review existing environmental data beforehand to understand site conditions and how this relates to observations made during the site assessment.

Image (left): Mapping out the piping run for a dispenser; Image (right): Contractor preparing a UST for removal.

What needs to be done to prepare for a site assessment?

Whenever a UST system is removed or closed in-place, a 30-day notification must be submitted to LARA; further information on the removal process for a UST system can be found here. If the existing UST system has not been previously registered with LARA, it is important to register the UST system before it is removed or closed in-place, particularly if a release is identified (refer to the last question below for why this is important).

Before site assessment samples can be collected, the UST has to be emptied; likewise, if the assessment samples are to be collected beneath the UST, the tank must first be removed. The dispenser piping should also be emptied/purged prior to the collection of assessment samples. Ideally, soils beneath the dispenser containment sump and piping run are exposed; however, there are other means of sample collection if the features are to be closed in-place.

Images (left and right): Removal of gasoline USTs.

Who performs the site assessment? Will a site assessment cause a delay in the upgrade schedule?

LARA indicates that an environmental professional should conduct the site assessment. Under most circumstances, the environmental professional (i.e., Qualified Consultant) can work with the contractor performing the site upgrades to avoid a delay to their work. In the rare instances when a significant release is identified, the O/O may choose to pause upgrade work so that grossly impacted soil can be removed from the source area, which will potentially lessen future site disturbance and reduce the long-term impact from the release.

What are the sampling/reporting requirements associated with a site assessment?

LARA has established prescriptive sampling requirements for a site assessment. Samples are collected from the bottom of the UST vault (or directly next to the UST if it is closed in-place) — two soil samples, or one aqueous sample if groundwater covers the excavation floor, or 1-for-1 water-for-soil sample if the excavation floor is partially covered with water. Beginning at the dispenser, a soil sample is collected every 30 feet beneath the piping run up to the UST. The analytical parameters are dependent on the petroleum fuel or chemical type.

If evidence of a release is observed, then a confirmed or suspected release (supported by soil staining, odors, etc. or a field meter response, respectively) must be reported to LARA within 24 hours of discovery. If any analytical parameters are detected in the site assessment samples, a confirmed release is submitted or the suspected release is upgraded to a confirmed release within 24 hours of receipt of the laboratory analytical results. If a UST system is removed or closed in-place, an amended Registration Form and results of the site assessment should be submitted to LARA within 45 days of the site assessment to remove the UST from the state’s registration fee database. The amended Registration Form should be submitted, regardless of whether a release is identified or not.

Image: Contractor preparing a site for the installation of new dispensers and piping runs.

What are the next steps after a release is confirmed?

If results from the site assessment confirm a release, the O/O must conduct corrective actions as required by Part 213, Leaking Underground Storage Tanks, of Act 451 of 1994, as amended, which is regulated by the Michigan Department of Environment, Great Lakes, and Energy (EGLE). Site characterization and exposure risk assessment must be conducted by an environmental Qualified Consultant; the first reporting deadline is 180 days after the release is identified. Environmental investigation and corrective actions/cleanup work may be eligible for reimbursement under the Michigan Underground Storage Tank Authority (MUSTA) fund, provided a proper site assessment (including notification of a release within the 24-hour period) was conducted for a registered UST system and the O/O has met their financial responsibility obligation (insurance) through MUSTA. For more information about using MUSTA funds, click here.

Envirologic has over 30 years of experience serving as an environmental professional for the private and public sector and has extensive expertise in conducting site assessments and UST site characterization/cleanup work. We offer many of the services mentioned above, including site assessments, reporting to LARA/EGLE, site characterization, corrective actions/cleanup work, and assistance with setting up reimbursement through MUSTA. If you have an upcoming UST upgrade project or general questions about the closure process for a UST system, please email Project Manager Paul French or call him at (269) 342-1100 ext. 116.


Posted in Blog, Environmental Investigation & Remediation, Underground Storage Tanks

What Are the Site Assessment Requirements for an Underground Storage Tank System?

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