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 Section 22a-449(d)-1 and Sections 22a-449(d)-101 through 22a-449(d)-114 of the Regulations of CT State Agencies (RCSA) are uncertain of the sampling and analytical methods required for UST closure. The following procedures outline the sampling and analytical method requirements of Sections 22a-449(d)-1(j) and 22a-449(d)-107 for UST Facilities, but owners and operators are responsible for ensuring that acceptable sampling and analysis is performed. Please contact DEEP Licensing and Enforcement Unit (LEU) staff by email at DEEP.USTEnforcement@ct.gov or by phone at (860) 424-3374 if you have any questions regarding these or other UST issues.
The UST owner or operator shall retain a person with a minimum of 3 years of experience and training in selecting and taking samples. Samples shall be taken, not later than 5 days after UST System closure. Samples from a stockpile, or other disturbed soil, do not satisfy these requirements. UST owners and operators must ensure that samples are obtained where contamination is most likely occur and that analyses are performed by a laboratory certified for the particular analysis by the Connecticut Department of Public Health. Sampling must be conducted in accordance with all applicable health and safety requirements, including following proper chain-of-custody protocols. Never enter an unsafe excavation for any reason.
Individual soil samples should be obtained from the underlying native soil, not from soil stockpiles, at each end of the tank, at the level of the tank bottom from each of the sidewalls, and from beneath the tank. If groundwater is present in the excavation, the sidewall samples should instead be obtained at the level of the groundwater, and a water sample must be collected. Sample locations shall include, at a minimum: (i) all sides and the bottom of the area where a tank has been removed or closed in-place; (ii) areas of staining; (iii) areas where holes or perforation in the removed tank are visible; (iv) areas beneath spill buckets, containment sumps, transition sumps, or dispensers; and (v) in the case of piping closure, at least one sample must be taken at every 10-foot interval of piping, for intervals of less than 10 feet, at least one sample must be taken. All samples should be analyzed by the appropriate analytical methods used to characterize petroleum releases.
DEEP considers the analytical methods listed in the table on the analytical methods used to characterize petroleum releases webpage to be acceptable in accordance with Sections 22a-449(d)-1(j) and 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). The Reasonable Confidence Protocols (“RCPs”) shall be used when there is a method published by the Department.
If contaminated soil, contaminated groundwater, 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 Sections 22-449(d)-1(i) and 22a-449(d)-106 of the Underground Storage Tank Regulations must be undertaken. For releases cleanups required pursuant Section 22a-449(d)-106, documentation of the UST removal and cleanup actions taken should be submitted to DEEP on the forms prescribed by the Commissioner. Please see the Underground Storage Tank Clean-Up webpage for more information on the UST release cleanup and required submittals.
For any unknown or other unlisted product, contact either the DEEP Corrective Action Unit at DEEP.LeakingUST@ct.gov or (860-424-3376) or the DEEP Licensing and Enforcement Unit staff at DEEP.USTEnforcement@ct.gov or (860) 424-3374.
For further information please contact either the DEEP Corrective Action Unit at DEEP.LeakingUST@ct.gov or (860-424-3376) or the DEEP Licensing and Enforcement Unit at DEEP.USTEnforcement@ct.gov or (860) 424-3374 or write to:
Additional Information
Notice of Completion of UST Closure Form
Pre-Notification of Scheduled Permanent Closure of USTs (tank or piping)
Analytical Methods Used to Characterize Petroleum Releases
Requesting the Commissioner's Approval for Additional Polluting Substances
Department of Public Health Environmental Laboratory Certification Program
DEEP Document Online Search Portal
Remediation Programs and Information
Content Last Updated October 2025