Sampling and Analytical Methods for Underground Storage Tank Closure

An Environmental Program Fact Sheet

The Connecticut Department of Energy and Environmental Protection (DEEP) recognizes that some owners and operators of underground storage tanks (USTs) regulated by Sections 22a-449(d)-101 through 22a-449(d)-113 of the Regulations of CT State Agencies (RCSA) are uncertain of the sampling and analytical methods required for UST closure. The following procedures satisfy the sampling and analytical method requirements of Section 22a-449(d)-107 for typical service station sites, but owners and operators are responsible for ensuring that acceptable sampling and analysis is performed. Please contact DEEP Storage Tank Enforcement and PCB Enforcement Unit staff by email at or by phone at (860) 424-3374 if you have any questions regarding these or other UST issues.

Samples from a stockpile or other disturbed soil do not satisfy these requirements. Owners and operators must ensure that samples are obtained where contamination is most likely to occur and that analyses are performed by a laboratory certified for the particular analysis by the Connecticut Department of Public Health. Sampling should be done by a person experienced in the proper collection and handling of such samples and must be conducted in accordance with all applicable health and safety requirements. Never enter an unsafe excavation for any reason.

Individual soil samples should be obtained from the underlying native soil at each end of the tank, at the level of the tank bottom from each of the sidewalls, and from beneath the tank. If ground water is present in the excavation, the sidewall samples should instead be obtained at the level of the water and a water sample must be collected. Samples should also be collected beneath dispensers and beneath product lines in the vicinity of fittings and at no more than twenty foot intervals along the piping. Prior to abandoning a UST in place, samples should be obtained in the vicinity of the fill pipe, at two or more locations immediately beneath the tank, and beneath piping as previously specified. All samples should be analyzed by the appropriate analytical methods used to characterize petroleum releases.

DEEP considers the analytical methods in the table provided at the link below to be acceptable in accordance with Section 22a-449(d)-107. Every sample, except as noted, should be analyzed for all potential contaminants listed for any product ever stored in the UST. Analyses must be performed with analytical reporting limits below the criteria identified in the Remediation Standard Regulations (Section 22a-133(k)-1 through 133(k)-3 of the RCSA).

If contaminated soil, contaminated ground water, or free product as a liquid or vapor is observed on site or is detected by sample analysis, the CT DEEP Emergency Response Unit must be immediately notified at (860) 424-3338 and corrective action in accordance with Section 22a-449(d)-106 of the Underground Storage Tank Regulations must be undertaken. That section requires cleanup “to the satisfaction of the commissioner”, which means in accordance with the Connecticut Remediation Standard Regulations. Documentation of the UST removal and cleanup actions taken should be submitted to DEEP.  The documentation can be submitted with the updated UST Notification Form through ezFile or through the DEEP’s Electronic Transmittal webpage.

In addition, DEEP must be notified of any significant environmental hazards, pursuant to Section 22a-6u of the Connecticut General Statutes. 

For any unknown or other unlisted product, contact either the DEEP Corrective Action Unit at or (860-424-3376) or the DEEP Licensing and Enforcement Unit staff at or (860) 424-3374.

For further information please contact either the DEEP Corrective Action Unit at or (860-424-3376) or the DEEP Licensing and Enforcement Unit at or (860) 424-3374. or write to:

Department of Energy and Environmental Protection
Bureau of Materials Management and Compliance Assurance
Emergency Response and Spill Prevention Division
DEEP Licensing and Enforcement Unit
79 Elm Street
Hartford, CT 06106-5127


Additional Information

QA/QC Guidance

Analytical Methods Used to Characterize Petroleum Releases

DEEP Document Online Search Portal

Remediation Programs and Information

Requesting the Commissioner's Approval for Additional Polluting Substances

Notification of Scheduled Permanent Closure of USTs (fillable Word) (PDF)


Content Last Updated December 2023