The owner or operator of an UST system shall ensure compliance with the following requirements:

1. (a) Operator response guidelines. The owner or operator shall post operator response guidelines in written form at each underground storage facility in accordance with subdivisions (1) and (2) of this subsection. The operator response guidelines shall include reporting procedures for releases and suspected releases, emergency contact phone numbers, malfunctioning equipment lock-out/tag-out and notification procedures, and initial mitigation protocol for releases, suspected releases and any other emergency. Such operator response guidelines shall be:

   1. (1) Visibly posted at each unmanned underground storage facility:

      1. (A) Where regulated substances are dispensed; and(B) If there is no dispensing, where regulated substances are stored; and(2) Posted for each manned underground storage facility, visually accessible in close proximity to the person manning the facility.

2. (b) Monthly inspections.

   1. (1) Monthly inspections shall be conducted at all underground storage facilities. A monthly inspection shall not occur within 7 days of any previous monthly inspection.
   2. (2) Monthly inspections shall be conducted by a Class B Operator, provided such Class B Operator has a working familiarity with specifics of the UST systems being inspected at the underground storage facility.
   3. (3) The monthly inspection shall, at a minimum, include an evaluation of all items specified in the “UST Monthly Inspection Checklist” posted on the department’s internet website. Any such inspection shall be performed in a manner that is in conformance with the 2021 version of the Petroleum Equipment Institute RP-900, “Recommended Practices for the Inspection and Maintenance of UST Systems” unless the commissioner has posted on the department’s internet website that use of such practice, or a portion thereof, is unacceptable and has posted an alternative.
   4. (4) The findings of each monthly inspection shall be recorded on the “UST Monthly Inspection Checklist” and when signed by the Class B operator shall become the inspection report. For each item, the inspector shall inspect the item and record on the inspection report either “pass” or “fail” to reflect the status of the item inspected. For any item that is not in compliance with applicable requirements or for which a “fail” status has been recorded, the owner or operator shall take all actions necessary to correct such failure or non-compliance and the inspection report shall note the actions that have been or will be taken. Any action taken in response to an inspection shall be performed as soon as possible, but if such action will take longer than 30 days after discovery of the need for such action, an explanation of why such action will take longer than 30 days shall be noted in the inspection report.
   5. (5) The results of each monthly inspection shall be maintained at the underground storage facility for a period of no less than 3 years from the date of such inspection.

3. (c) Annual inspections.

   1. (1) Annual inspections shall be conducted at all underground storage facilities. An annual inspection shall occur within 90 days of the one-year anniversary date of the previous annual inspection.
   2. (2) Annual inspections shall be conducted by an independent third-party qualified and with experience performing such inspections. Such individual shall meet the qualification requirements set forth in the 2021 version of the Petroleum Equipment Institute RP-900, “Recommended Practices for the Inspection and Maintenance of UST Systems”.
   3. (3) Annual inspections shall, at a minimum, include an evaluation of the items specified in the “UST Annual Inspection Checklist” posted on the department’s internet website. Any such inspection shall be performed in accordance with the 2021 version of the Petroleum Equipment Institute RP-900, “Recommended Practices for the Inspection and Maintenance of UST Systems” and any applicable manufacturer’s instructions, unless the commissioner has posted on the department’s internet website that use of such practice or instructions, or a portion thereof, is unacceptable and has posted an alternative.
   4. (4) The findings of each annual inspection shall be recorded on the “UST Annual Inspection Checklist” and when signed by the individual who conducted the inspection, shall become the inspection report. For each item, the inspector shall inspect the item and record on the inspection report either “pass” or “fail” to reflect the status of the item inspected. For any item that is not in compliance with applicable requirements or for which a “fail” status has been recorded, the owner or operator shall take all actions necessary to correct such failure or non-compliance and the inspection report shall note the actions that have been or will be taken. Any action taken in response to an inspection shall be performed as soon as possible, but if such action will take longer than 30 days after discovery of the need for such action, an explanation of why such action will take longer than 30 days shall be noted in the inspection report.
   5. (5) The results of each annual inspection shall be maintained at the underground storage facility for a period of not less than 3 years from the date of such inspection.

4. (d) Tanks and piping. The owner or operator of an UST system shall ensure compliance with the following requirements:

   1. (1) Prevent the release or loss of liquid from any part of a tank and connected piping and maintain all such tanks and connected piping in accordance with a code of practice developed by a nationally recognized association or independent testing laboratory and in accordance with the manufacturer’s instructions. If use of any manufacturer’s specifications and recommendations are required under this section and such specifications or recommendations are inconsistent with any provision of this section, the provision which imposes the most stringent and protective requirement shall be required.

   2. (2) Except as provided for in subsection (f) of this section, each double-walled UST and double-walled connected piping shall be tested to determine if there is a release or any loss of liquids from any part of such tank or piping, as applicable. The test required by this subdivision shall:

      1. (A) Be performed in accordance with the manufacturer’s specifications. If there are no manufacturer’s specifications, the owner or operator shall perform such test in accordance with an applicable method specified in an industry code or engineering standard. If there are no applicable manufacturer’s specifications, industry codes, or engineering standards, the owner or operator shall perform such tests using a test method that, before use, is approved by a registered professional engineer licensed in the state of Connecticut;
      2. (B) Be performed by a qualified individual or company who has the training and experience to perform and document the results of such testing; and(C) Beginning May 7, 2025, such testing shall be performed not later than 3 years after the date of the previous test or the date of installation of the tank and piping, as applicable, whichever date is later, and once every 3 years thereafter, provided that for any testing performed to comply with this subdivision, there is at least one year between tests.

5. (e) Spill buckets and containment sumps. The owner or operator of an UST system shall ensure compliance with the following requirements:

   1. (1) Any liquid that accumulates in any part of a spill bucket or containment sump remains in such spill bucket or containment system, such that there is no release or loss of liquids.

   2. (2) Except as provided for in subsection (f) of this section, all spill buckets and containment sumps shall be tested to determine whether any liquid that may accumulate in such sump or spill bucket is prevented from leaving such sump or spill bucket. The test shall:

      1. (A) Be performed in accordance with the manufacturer’s specifications. If there are no manufacturer’s specifications, the owner or operator shall perform such test in accordance with an applicable method specified in an industry code or engineering standard. If there are no applicable manufacturer’s specifications, industry codes, or engineering standards, the owner or operator shall perform such tests using a test method that, before use, is approved by a registered professional engineer licensed in the state of Connecticut;
      2. (B) Be performed by a qualified individual or company who has the training and experience to perform and document the results of such testing; and(C) Beginning May 7, 2025, be performed not later than 3 years after the date of the previous test or the date of installation, whichever date is later, and once every 3 years thereafter, provided that for any testing performed to comply with this subdivision there is at least one year between tests.

6. (f) Provisions applicable to testing. The following shall apply to testing required by subsections (d) and (e) of this section:

   1. (1) The testing shall not be required for a double-walled UST system component using continuous monitoring that automatically monitors both the primary and secondary containment of such tank system, such as systems that are hydrostatically monitored or under constant vacuum; and(2) Notwithstanding subsections (d)(2) and (e)(2) of this section, an owner or operator shall not use a test method to comply with this subsection if the commissioner has posted on the department’s internet website that use of such test method is unacceptable. In addition, the commissioner may post test methods deemed acceptable on the department’s internet website.

7. (g) Overfill prevention equipment. The owner or operator of an UST system shall ensure compliance with the following requirements:

   1. (1) An UST system’s overfill prevention equipment shall:

      1. (A) Automatically shut off flow into an UST when such UST is no more than 95 percent full; or (B) Alert the transfer operator when an UST is no more than 90 percent full by triggering a high-level alarm that is both audible and visual.

   2. (2) Overfill prevention equipment shall be tested to determine if such equipment will activate as specified in subdivision (1) of this subsection.

      1. (A) The test required by this subdivision shall:

8. (i) Be performed in accordance with the testing specified in the 2021 version of the Recommended Practices of the Petroleum Equipment Institute RP-900, “Recommended Practices for the Inspection and Maintenance of UST Systems”;

   1. (ii) Be performed by a qualified individual or company who has the training and experience to perform and document the results of such testing; and(iii) Be conducted annually, provided that for the testing to comply with this subdivision, there is at least 9 months between tests.
   2. (B) An owner or operator shall not use a test method to comply with this subdivision if the commissioner has posted on the department’s internet website that use of such test method is unacceptable. In addition, the commissioner may post test methods deemed acceptable on the department’s internet website.

9. (h) Operation and maintenance of corrosion protection. The owner or operator of an UST system shall ensure compliance with the following requirements:

   1. (1) All corrosion protection systems shall be operated and maintained to continuously provide corrosion protection to the metal components of that portion of the UST that routinely contain regulated substances and are in contact with the ground or water. Such corrosion protections shall, at a minimum, be maintained continuously at least minus 0.85 volts, measured between the structure and a copper-copper sulfate electrode.

   2. (2) Cathodic protection systems shall be tested by measuring the voltage between the structure and a copper-copper sulfate electrode. A passing test shall be at least minus 0.85 volts measured between the structure and a copper-copper sulfate electrode. Voltage drops other than those across the structure electrolyte boundary shall be considered for valid interpretation of the voltage measurements. Such test shall be performed:

      1. (A) In accordance with a code of practice developed by a nationally recognized association;
      2. (B) By a qualified cathodic protection tester who can document the results of such testing. A qualified cathodic protection tester means a person who can demonstrate an understanding of the principles and measurements of all common types of cathodic protection systems as applied to metal piping and UST systems in contact with soil or water. At a minimum, such persons shall have education and experience in soil resistivity, stray current, structure-to-soil potential, and component electrical isolation measurements of buried metal piping and tank systems; and(C) Within 6 months of installation and once a year thereafter, provided that there is at least 9 months between tests.
10. (i) Metallic piping. The owner or operator of an UST system with metallic piping that is not cathodically protected shall prevent such piping from coming into direct contact with the ground or any water for the operational life of such piping. This requirement does not apply to metallic piping that is not designed to routinely contain regulated substances.

11. (j) Maintaining proper operability. The owner or operator of an UST system shall ensure that the UST system components specified in sections 22a-449(d)-102, 22a-449(d)-103 and 22a-449(d)-104 of the UST regulations:

    1. (1) Remain in good working order and operate properly and if a repair is needed, such repair shall be promptly made in compliance with subsection (m) of this section; and(2) Are not disabled or rendered inoperable. This includes ensuring water does not accumulate in the spill buckets and such buckets remain clean and dry, and that automatic shut-off equipment is not disabled during the filling of an UST;

12. (k) Transfer of liquids. The owner or operator of an UST system shall ensure that the transfer of regulated substances into a tank is constantly monitored and that releases, such as spills or overfills, do not occur during any such transfer. The owner or operator shall ensure that the volume available in the tank is greater than the volume of product to be transferred to the tank before the transfer is made and that the transfer operation is monitored constantly to prevent overfilling and spilling.

    1. (1) The owner or operator of an UST system shall only use an UST system that is made of materials that are compatible with the regulated substance which is stored in such system. This requirement shall apply to the entirety of an UST system.

    2. (2) (A) The owner or operator of an UST system storing greater than 10 percent ethanol or greater than 20 percent biodiesel shall demonstrate that such substances are compatible with the UST system by:

       1. (i) Certification or listing of the UST system components by a nationally recognized independent testing laboratory for use with such regulated substances; or(ii) An affirmative statement of compatibility in writing from the equipment or component manufacturer that specifies the range of biofuel blends with which the UST system component is compatible; and(iii) Documentation from the manufacturer indicating that the regulated substances stored in such UST system are compatible with the UST system.
       2. (B) Documentation demonstrating compliance with the requirements of subparagraph (A) of this subdivision shall be maintained in accordance with section 22a-449(d)-114 of the UST regulations.

    (l) Compatibility.

13. (m) Repairs.

    1. (1) General Requirement. Except for the UST system components specified in this subsection, the owner or operator shall immediately repair any UST system component in need of repair. All such repairs shall comply with the requirements of this subsection, as applicable.

    2. (2) Specific Equipment That Can Only Be Repaired Under Certain Conditions. An owner or operator of an UST system shall only make repairs to the following equipment if the requirements of this subdivision are satisfied:

       1. (A) For cathodic protection equipment, only if such equipment passed the cathodic protection test required by subsection (h)(2) of this section within the previous 5 years;
       2. (B) For a containment sump, only if such repairs performed after May 7, 2025 result in the sump meeting the requirements of section 22a-449(d)-102(a)(5)(C) of the UST regulations;
       3. (C) For single-walled fittings or pipe sections, only if such fitting or pipe section is 3 feet or less. The replacement of fittings or pipe sections of greater than 3 feet is permitted if the replacement piping or fitting is in compliance with section 22a-449(d)-102 of the UST regulations; and(D) For a fiberglass-reinforced plastic tank, only if such repair is made by the manufacturer’s authorized representative.

    3. (3) Equipment That Cannot Be Repaired. An owner or operator of an UST system shall not repair, but shall immediately discontinue use and permanently close the following UST system components in accordance with section 22a-449(d)-107 of the UST regulations:

       1. (A) A tank that is comprised of steel or of a composite that includes steel; or(B) A tank or piping that does not pass the annual cathodic protection test required by subsection (h)(2) of this section and the owner or operator of such tank or piping cannot demonstrate that such tank or piping has passed such test within the 5 years prior to such failed test.

    4. (4) Requirements for Conducting Repairs.

       1. (A) (i) Once it is determined that an UST system or UST system component needs repair, and such repair is permitted to be made in accordance with this section, the owner or operator of such UST system or UST system component shall ensure that:

       2. (I) No regulated substances are delivered to such UST system if there is a release from such system or if the delivery of a regulated substance to such system could result in a release;

          1. (II) No regulated substances are dispensed from such UST system if dispensing such substances could result in a release; and(III) If the repair is to a tank associated with such UST system or piping that routinely contains regulated substances, any regulated substances are immediately emptied from such UST system prior to the repair.
          2. (ii) The requirements of this subparagraph shall remain in effect until the UST system or UST system component is successfully repaired and passes the applicable test, in accordance with the requirements of subparagraphs (B) and (C) of this subdivision.
       3. (B) The owner or operator shall ensure that all repairs allowed by this section are conducted in accordance with the manufacturer’s specifications, a code of practice developed by a nationally recognized association or an independent testing laboratory.
       4. (C) (i) Immediately after a repair, the owner or operator shall ensure that the repaired UST system or UST system component passes a test specified in this subparagraph prior to being put back into service:

       5. (I) For a repair to a single-walled non-metallic tank associated with an UST system, a tank tightness test 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;

          1. (II) For a repair to single-walled piping, a tightness test capable of detecting a 0.1 gallon per hour leak rate at one and one-half times the operating pressure of such piping;
          2. (III) For a repair to a double-walled tank associated with an UST system or double-walled piping, a test of the interstitial space in such tank or piping demonstrating that there is no release or loss of liquid from either the primary or the secondary containment of such tank or piping, as applicable;
          3. (IV) For a repair to a cathodic protection system, a test conducted in accordance with subsection (h)(2) of this section;

       6. (V) For a repair to spill prevention equipment, a test to determine if the equipment is liquid tight by using vacuum, pressure, or hydrostatic testing. Before use of such test, if requested, the commissioner may approve in writing, another test method;

          1. (VI) For any repair to overfill prevention equipment, release detection equipment or the shear valve or crash valve on a dispenser, a test of functionality to ensure that the equipment is functioning properly; and(VII) For a repair to a piping containment sump or under-dispenser containment sump, a test to determine that the repaired sump meets the requirements of section 22a-449(d)-102(a)(5)(C) of the UST regulations.
          2. (ii) The owner or operator of an UST system shall ensure that any test conducted to satisfy the requirements of subparagraph (B) of this subdivision shall be performed in accordance with the manufacturer’s specifications. If there are no manufacturer specifications, the owner or operator shall perform such tests in accordance with an applicable method specified in an industry code or engineering standard. If there are no applicable manufacturer specifications, industry codes, or engineering standards, the owner or operator shall perform such tests using a test method that, before use, is approved in writing, by a registered professional engineer licensed in the state of Connecticut. The owner or operator shall ensure that the person who performs the testing required by subparagraph (B) of this subdivision has the qualifications and expertise to perform such testing and the owner or operator shall maintain the results of such testing in accordance with section 22a-449(d)-114 of the UST regulations.
          3. (iii) Notwithstanding subparagraph (B) of this subdivision, an owner or operator of an UST system shall not use a test method to comply with subparagraph (A) of this subdivision if the commissioner has posted on the department’s internet website that the use of a test method is unacceptable. In addition, the commissioner may post test methods deemed acceptable on the department’s internet website.

    5. (5) Requirements Regarding Removal or Replacement of Containment Sumps and Spill Buckets (A) Whenever a containment sump or spill bucket is removed or replaced, for any reason, the owner or operator shall ensure that:

       1. (i) A person, with the training specified in this subparagraph, is present at the underground storage facility to oversee such removal or replacement. Such person, before such removal or replacement, shall have:

       2. (I) Received certification of successful completion of training in accordance with 29 CFR 1910.120(e) and as applicable, annual refresher training required in accordance with 29 CFR 1910.120(e)(8); and(II) Successfully passed an examination listed on the department’s internet website, such as the International Code Council Decommissioning Exam U2.

          1. (ii) The containment sump or spill bucket, as applicable, is emptied and cleaned by removing all liquids and accumulated sludges in accordance with a code of practice developed by a nationally recognized association. After removal of such liquids and sludges, the containment sump, or spill bucket, as applicable, shall be removed from the ground.

          2. (iii) (I) An assessment is performed in accordance with this subparagraph not later than 5 days after the containment sump, or spill bucket, as applicable, has been removed from the ground in accordance with section 22a-449(d)-107 of the UST regulations. The assessment shall include an evaluation of the presence of a release or potential release at all locations where contamination is most likely to be present. At a minimum, this assessment shall be adequate to determine if there is a release or potential release in the area where the containment sump or spill bucket, as applicable, has been removed. The selection of sample types, sample locations, and analytical methods, shall take into account: the nature of the stored substance, the type of backfill, the depth to ground water, the presence of rainwater or groundwater, and other factors appropriate for identifying the presence, or potential presence, of a release;

             1. (II) Only a person with a minimum of 3 years of experience and training in selecting and taking samples shall undertake the assessment required by this subparagraph. 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 that is either certified by the Connecticut Department of Public Health or approved in writing by the commissioner; and(III) All analytical data used to comply with this section shall be scientifically valid and defensible, with a level of precision, accuracy, and sensitivity commensurate with its intended use. All analytical data shall include an analytical data quality assessment and data usability evaluation prepared by an individual qualified to make such assessment or evaluation. If the commissioner determines that analytical data is not scientifically valid and defensible, or is not of a sufficient level of precision, accuracy, and sensitivity to support the intended use of the data, the commissioner shall identify in writing the reasons for such conclusions and such data shall not be relied upon to demonstrate compliance with this section.
       3. (B) If any time during the replacement of a containment sump or spill bucket, as applicable, a release is:

14. (i) Suspected, the owner or operator of the UST system shall comply with section 22a-449(d)-105 of the UST regulations; or(ii) Confirmed, the owner or operator of the UST system shall comply with section 22a-449(d)-106 of the UST regulations.

    1. (C) Sump or Spill Bucket Removal or Replacement Report. Not later than 30 days after completing the sampling necessary for the assessment required by subdivision (5)(A)(iii) of this subsection, the owner or operator of the UST system shall ensure that a detailed report is prepared regarding the removal or replacement of a containment sump or spill bucket, as applicable. Such report shall include at a minimum:

15. (i) A description of the underground storage facility, including any UST systems in use and general characteristics of the area in which the facility is located;

    1. (ii) A detailed description of the replacement or removal activities undertaken;
    2. (iii) A detailed description and justification for the sample locations, sample depths, analytical methods used, and quality assurance/quality control measures taken;
    3. (iv) A detailed analysis of the analytical results. This analysis shall include:

    4. (I) All sampling results and a justification for disregarding or not using any sampling results;

       1. (II) A description of the distribution and concentration of any substances in soil or groundwater that may have been released from the underground storage facility;
       2. (III) A description of the general characteristics of soil in the vicinity of the underground storage facility;
       3. (IV) A map to scale showing the extent and concentration of all releases;

    5. (V) The tabulated analytical results of all laboratory analysis of soil and groundwater;

       1. (VI) A description of the experience and training of the person undertaking the assessment required by subsection (m)(5) of this section; and(VII) Any other information specified by the commissioner.
    6. (D) The report required under subdivision (5)(C) of this subsection shall be submitted to the commissioner on a form and in a manner specified by the commissioner:
16. (i) If the results of the assessment undertaken pursuant to subdivision (5)(A) of this subsection indicate an exceedance of any applicable criterion of the RSRs or the release or potential release of a substance for which there is no criterion under the RSRs; or(ii) Upon request by the commissioner within the time frame specified in any such request. If no time frame is specified in the request, the report shall be provided not later than 30 days after receipt of the commissioner’s request.
17. (n) Additional activities.If the activities undertaken pursuant to this section are not satisfactory to the commissioner, the commissioner shall notify the owner or operator in writing, identifying what the commissioner deems unsatisfactory, the reasons why and what additional actions are necessary. The owner or operator shall undertake any actions requested by the commissioner within the time frame specified by the commissioner. If no time frame is specified in any such request, the requested actions shall be undertaken not later than 60 days from the date of any such request.
18. (o) Cooperation.The owner and operator of an UST system shall cooperate fully with any inspection, monitoring and testing conducted by the department, as well as any request for document submission, testing, and monitoring by the owner or operator pursuant to the UST regulations and any applicable Connecticut General Statute administered by the commissioner.
19. (p) Recordkeeping.For purposes of section 22a-449q of the Connecticut General Statutes, the records required to be maintained pursuant to section 22a-449(d)-103 of the UST regulations shall be those specified in section 22a-449(d)-114(b) of the UST regulations.

(Effective July 28, 1994; Amended December 1, 2021; Amended May 7, 2025)