1. (a) Suspected releases.

   1. (1) The conditions identified in this subdivision shall constitute a suspected release.

      1. (A) The discovery by an owner or operator or any other person of a release of regulated substances at an underground storage facility or in the surrounding area including the presence of NAPL or vapors in soils, basements, sewer and utility lines, and nearby surface water;
      2. (B) Unusual operating conditions, including:

2. (i) Erratic behavior of product dispensing equipment;

   1. (ii) The sudden loss of product from an UST system;
   2. (iii) An unexplained presence of water in the tank;
   3. (iv) Any condition or monitoring result, such as an alarm, indicative of the failure of an UST system;
   4. (v) Any condition in the secondary containment system, such as liquid in sumps or interstitial space, indicative of a potential release; or(vi) A visual inspection that indicates a release may be occurring.
   5. (C) A failed test of any UST system component such as:

3. (i) a failed tank tightness test;

   1. (ii) a failed line leak detector;
   2. (iii) a failed cathodic protection test;
   3. (iv) a failed test of a piping containment sump;
   4. (v) a failed test of an under-dispenser containment sump;
   5. (vi) a failed test of a spill bucket; or(vii) a failed test of interstitial space on any component.
   6. (D) Monitoring results from a release detection method pursuant to section 22a-449(d)-104 of the UST regulations that indicate that a release may have occurred, regardless of whether or not the method is being used as the primary method of release detection. Except that no further action shall be required under this section if:

4. (i) Such monitoring device is found to be defective and is immediately repaired, recalibrated or replaced, and additional monitoring does not confirm the initial result; or(ii) An alarm was investigated and the owner or operator determined that the alarm was not the result of a failure of the UST system.

   1. (2) Any UST system equipment or component that is found to be defective, but not leaking, and that is immediately repaired or replaced shall not be considered an unusual operating condition for purposes of subdivision (1)(B) of this subsection provided the owner or operator can demonstrate, through documentation, the basis upon which it was determined that the UST system equipment or component was not leaking.
5. (b) Investigation due to off-site impacts.The Owner or operator of an UST system shall follow the procedures in subsection (c) of this section to determine if such UST system may be the source of off-site impacts when such impacts are discovered by the owner or operator or are reported to the owner or operator by any other person. These impacts include, but are not limited to, the presence of NAPL or vapors in soils, basements, sewer and utility lines, and nearby surface and drinking water.

6. (c) Reporting and investigating suspected releases and confirmation steps.Unless corrective action is initiated in accordance with section 22a-449(d)-106 of the UST regulations, the owner or operator shall immediately investigate any suspected release listed in this section. Such investigation shall include:

   1. (1) Report. A suspected release shall be reported to the commissioner, not later than 24 hours after the discovery. Such report shall be on a form and in a manner prescribed by the commissioner on the department’s internet website.

   2. (2) (A) Tightness test. The owner or operator shall complete a tightness test of the UST system not later than 72 hours after the discovery of any suspected release; however, a tightness test need not be conducted if no further action is required under subsection (a)(1)(D) of this section. Unless requested by the commissioner, such test does not need to include spill buckets, or vent and vapor recovery piping that does not routinely contain product. Any such tightness testing shall comply with the following:

      1. (i) For a tank, be capable of detecting a 0.1 gallon per hour leak rate from any portion of the tank while accounting for the effects of thermal expansion or contraction of the product, vapor pockets, tank deformation, evaporation or condensation, and the location of the water table;
      2. (ii) For piping, be capable of detecting a 0.1 gallon per hour leak rate at one and one-half times the operating pressure of such piping; and(iii) For a containment sump, be performed in accordance with section 22a-449(d)-103(e)(2) of the UST regulations.
      3. (B) Under-dispenser containment sump, piping containment sump and spill buckets. If the suspected release is due to an alarm, sensor or similar device in a containment sump or spill bucket indicating that liquid may be present in such sump or spill bucket, or if there is liquid observed in any such sump or spill bucket, the owner or operator of such sump or spill bucket shall:

7. (i) Immediately investigate and if applicable, determine if liquid is present. If liquid is present, identify the cause for the presence of such liquid;

   1. (ii) Immediately remove all liquid and ensure that any liquid removed is managed and disposed of in accordance with all applicable federal, state, and local requirements;
   2. (iii) Immediately take corrective measures to prevent liquid from accumulating in such sump or spill bucket, including preventing water from outside the UST system from accumulating in a sump or spill bucket; and(iv) Unless such containment sump or spill bucket has passed a tightness test within the previous 30 days, not later than 48 hours after liquid in the sump or spill bucket has been removed, perform such test in accordance with section 22a-449(d)-103(e)(2) of the UST regulations. If the test results indicate that the containment sump or spill bucket is not liquid tight, as soon as practicable, but not later than 5 days after obtaining such test results, the owner or operator shall conduct a site check pursuant to subdivision (4) of this subsection.
   3. (C) Visual inspection. If a visual inspection of any part of an UST system that is not included in a test performed pursuant to subparagraph (B)(iv) of this subdivision indicates a release is or may be occurring, the owner or operator shall immediately repair the component causing such condition to eliminate such suspected release or release.
   4. (D) As soon as practicable, but not later than 5 days after a suspected release is discovered, the owner or operator shall conduct a site check pursuant to subdivision (4) of this subsection, if:

8. (i) Environmental contamination is the basis for suspecting a release; or(ii) After taking the steps identified pursuant to subparagraphs (A) to (C), inclusive of this subdivision, the owner or operator cannot determine whether a release has occurred.

   1. (E) If the commissioner determines that a suspected release has, or may have, occurred, in addition to the testing required by this section, the commissioner may require additional testing the commissioner deems necessary.
   2. (F) For the purposes of this subdivision, any test deemed inconclusive shall constitute a failed test.

   3. (3) Failures. If after taking the steps identified in subdivisions (2)(A) to (2)(C), inclusive, of this subsection, a failure is indicated, the owner or operator shall determine the source of such failure. If the source of such failure indicates that:

      1. (A) A regulated substance is, or may be, emanating from an UST system, the owner or operator shall begin corrective action in accordance with section 22a-449(d)-106 of the UST regulations and;

9. (i) Repair the UST system pursuant to section 22a-449(d)-103(m) of the UST regulations, and if applicable temporarily close such tank in accordance with section 22a-449(d)-110 of the UST regulations; or(ii) Permanently close such UST system in accordance with section 22a-449(d)-107 of the UST regulations;

   1. (B) A regulated substance is not emanating from the UST system, the owner or operator shall repair or replace any part of the UST system determined to be in need of repair or replacement pursuant to section 22a-449(d)-103(m) of the UST regulations.
   2. (4) Site check. The owner or operator shall measure for the presence of a release where contamination is most likely to be present. In selecting sample types, sample locations, and measurement methods, owners and operators shall consider the nature of the stored substance, the type of initial alarm or cause for suspicion, the type of backfill, the depth of ground water, and other factors appropriate for identifying the presence and source of the release. Unless otherwise approved by the commissioner in writing, sample collection and analysis shall comply with appropriate chain-of-custody procedures to ensure sample integrity and all samples shall be analyzed by a laboratory certified by the Connecticut Department of Public Health to perform such analyses.

(Effective July 28, 1994; Amended May 7, 2025)