1. (a) Immediate Action Required (1) An immediate action, performed pursuant to the requirements of this section, shall be required upon discovery of a release to the land and waters of the state if such release is:

   1. (A) An emergent reportable release; or(B) A significant existing release.
   2. (2) An immediate action shall continue until it has achieved either an immediate action transition-point identified in subsection (h) of this section or the standards identified in the cleanup standards sections of the RBCRs.
   3. (3) If an immediate action is required by this section but such action has not been undertaken or an immediate action has not been performed pursuant to the requirements of this section, including but not limited to, the failure to comply with a deadline specified in this section, the failure to satisfy a cleanup standard or transition-point identified by subdivision (2) of this subsection, or the failure to submit an immediate action report identified in subsection (k) of this section, the commissioner may take any action authorized by section 22a-134rr or 22a-134ss of the Connecticut General Statutes, including issuing a cease and desist order pursuant to section 22a-134ss(g) of the Connecticut General Statutes. Nothing in this section shall affect the commissioner’s ability to take enforcement action under any other provision of statute or regulation.

2. (b) Emergencies and Exigent Conditions (1) Upon receiving a report of an emergent reportable release or a significant existing release, the commissioner may, in the commissioner’s sole discretion, determine such release to be an emergency or exigent condition and may direct the response to such release.

   1. (2) If the commissioner responds to such an emergency or exigent condition, on-site or otherwise, the commissioner may direct any person who created or is maintaining such release to perform any action necessary to investigate, stabilize, contain, mitigate, remediate, remove, or monitor such release or to protect human health or the environment, which shall include, but not be limited to, any remediation or other action necessary to achieve an immediate action transition-point specified in subsection (h) of this section or a standard specified in the cleanup standards sections of the RBCRs.
   2. (3) If an action directed by the commissioner pursuant to this subsection is not performed as directed by the commissioner or is not able to be performed by the person who created or maintained the release in the timeframe necessary to protect human health or the environment, the commissioner may perform such action, or may retain an appropriately licensed contractor to perform such action, and may seek to recover eligible costs pursuant to section 22a-451 of the Connecticut General Statutes and may take any authorized enforcement action including, but not limited to, actions authorized by sections 22a-134rr to 22a-134ss, inclusive, of the Connecticut General Statutes including issuing a cease and desist order pursuant to section 22a-134ss(g) of the Connecticut General Statutes, or an administrative civil penalty pursuant to sections 22a-134ss(f) and 22a-6b of the Connecticut General Statutes, including a schedule of penalties adopted pursuant thereto.
   3. (4) The commissioner shall determine, in the commissioner’s sole discretion, when an emergency or exigent condition caused by a release has been abated. The commissioner may determine that an emergency or exigent condition has been abated without achieving either an immediate action transition-point specified by subsection (h) of this section or a standard specified in the cleanup standards sections of the RBCRs. Upon determining that the emergency or exigent condition has been abated, the commissioner may end any response to such release. At the conclusion of any response directed by the commissioner, provided the response directed has not achieved an immediate action transition-point or a cleanup standard, each person who created or is maintaining such release shall continue the actions required to achieve an immediate action transition-point or a cleanup standard within the time specified by subsection (h) of this section.

3. (c) Time to Begin Required Immediate Actions (1) The actions required by subsections (d) and (e) of this section shall begin immediately upon discovery of an emergent reportable release, if practicable, and under no circumstances later than 2 hours after discovery of such release. No time period or deadline specified by this section shall delay any action necessary to investigate, stabilize, contain, mitigate, remediate, remove, or monitor such release. When actions are necessary to provide safe access to a release area, the actions required by subsections (d) and (e) of this section shall be determined to begin upon initiation of such necessary actions.

   1. (2) The actions required by subsections (d) and (f) of this section shall begin immediately upon discovery of a significant existing release, if practicable, and under no circumstances later than any deadline for action specified in this section after such release is reported as required by section 22a-134tt-3 of the RBCRs. No time period or deadline specified by this section shall delay any action necessary to investigate, stabilize, contain, mitigate, remediate, remove, or monitor such release.
   2. (3) If the immediate actions specified by subsection (d) of this section, and subsection (e) or (f), as applicable, are not underway and the time frame specified by this subsection has passed, the commissioner may perform such action, or may retain an appropriately licensed contractor to perform such action, and may seek to recover eligible costs pursuant to section 22a-451 of the Connecticut General Statutes and may take any authorized enforcement action including, but not limited to, actions authorized by sections 22a-134rr to 22a-134ss, inclusive, of the Connecticut General Statutes including issuing a cease and desist order pursuant to section 22a-134ss(g) of the Connecticut General Statutes, or an administrative civil penalty pursuant to section 22a-134ss(f) and section 22a-6b of the Connecticut General Statutes, including a schedule of penalties adopted pursuant thereto.

4. (d) Required Immediate Actions (1) Upon discovery of an emergent reportable release or a significant existing release, each person who created or is maintaining such release shall take immediate action to investigate, stabilize, contain, mitigate, remediate, remove, or monitor such release, as required to meet an immediate action transition-point specified by subsection (h) of this section or a cleanup standard specified in the cleanup standards sections of the RBCRs. Such actions shall include, but shall not be limited to:

   1. (A) Removing from:

5. (i) an improved surface of the land and waters of the state, to the standard specified in section 22a-134tt-8(a)(1)(F)(ii), an emergent reportable release;

   1. (ii) the land and waters of the state, to the maximum extent practicable, an emergent reportable release; or(iii) to the extent necessary to comply with this section, a significant existing release, using means appropriate for the specific substance released and the land and waters impacted by such release;
   2. (B) Implementing measures to prevent migration of a release, which may include, but shall not be limited to, active remediation techniques or the use of physical barriers or appropriate treatment systems; and(C) Identifying the source of a release and eliminating the source of an emergent reportable release or, if practicable in the time provided to complete immediate actions, eliminating the source of a significant existing release.
   3. (2) Closure characterization of the nature and extent of a release shall not be required before commencing an immediate action. Characterization of the nature and extent of the release shall be performed at the same time as the required immediate actions to ensure that such required actions are sufficient and successful. At a minimum, characterization sufficient to demonstrate that an immediate action transition-point specified by subsection (h) of this section has been achieved shall be developed during the timeframe specified for achieving an immediate action transition-point, except that should the actions performed include remediation to a standard specified in the cleanup standards sections of the RBCRs, closure characterization of such release pursuant to section 22a-134tt-4 of the RBCRs shall be required.

6. (e) Required Immediate Actions for an Emergent Reportable Release (1) In addition to the actions specified by subsection (d) of this section, the following actions shall be required if a release is an emergent reportable release that is impacting a public or private drinking water well:

   1. (A) Install, as soon as is practicable, physical barriers to prevent the further migration of such release, which may include, but shall not be limited to, interceptor trenches, sheet piles or slurry walls, and implement, as soon as is practicable, hydraulic control and recovery measures, which may include but shall not be limited to, recovery wells, absorbent socks, bailing, or vacuuming;
   2. (B) Identify each public or private drinking water well located on each parcel abutting the parcel on which the impacted well is located provided that such well is within 1,000 feet of the impacted well, collect samples of water from such wells, and send for laboratory analysis as soon as is practicable but not more than 36 hours after discovery that a public or private drinking water well has been impacted by such release;
   3. (C) Identify each public or private drinking water well located within 200 feet of an impacted well, or within 500 feet downgradient of an impacted well, collect samples of water from such wells, and send for laboratory analysis as soon as is practicable but not more than 36 hours after discovery that a public or private drinking water well has been impacted by such release;
   4. (D) Ensure that an alternative source of potable water is provided to the users of each public or private drinking water well impacted by such release;
   5. (E) Seven days after the collection of samples from a public or private drinking water well pursuant to subparagraph (B) and (C) of this subdivision, collect a second sample of water from each well tested and send for laboratory analysis;
   6. (F) For each drinking water well impacted by the release of a substance at a concentration greater than the groundwater protection criterion, install an appropriate treatment system for such substance or connect to an unimpacted public drinking water supply system. Each treatment system shall be installed not more than 15 days following discovery that such well has been impacted by the release, unless such drinking water well will be replaced with a connection to an unimpacted public water supply system. Each connection to an unimpacted public drinking water supply system shall be made not more than 30 days following discovery of such impacted well; and(G) As soon as practicable, but not more than 45 days following discovery that such release has impacted a public or private drinking water well, prepare and submit to the commissioner an immediate action report, pursuant to subsection (k) of this section, that:

7. (i) Lists each drinking water well identified pursuant to subparagraph (B) and (C) of this subdivision, specifies whether each drinking water well has been impacted by such release, and includes the results of laboratory analysis of all samples collected from such wells;

   1. (ii) Identifies each treatment system installed and each connection to an unimpacted public drinking water supply system made. For each treatment system installed, a schedule for the maintenance and monitoring of such system shall be specified;
   2. (iii) For each drinking water well impacted by a substance at a concentration equal to or less than the groundwater protection criterion, and for each drinking water well within 200 feet of a drinking water well impacted by such release, provides a schedule for the quarterly monitoring of such well for substances associated with such release; and(iv) Includes a description of those measures undertaken to prevent further migration of the release, pursuant to subparagraph (A) of this subdivision, and a schedule for the maintenance, and monitoring of such measures;
   3. (H) The commissioner may request a follow up report be submitted pursuant to section 22a-450-4(b) of the Regulations of Connecticut State Agencies, and may specify a deadline for the submission of such a report;

   4. (2) In addition to the actions specified by subsection (d) of this section, the following actions shall be required if a release is an emergent reportable release that is impacting groundwater in a groundwater monitoring well within 500 feet in any direction of a public or private drinking water well:

      1. (A) Install, as soon as is practicable, physical barriers to prevent the further migration of such release, which may include, but shall not be limited to, interceptor trenches, sheet piles or slurry walls, and implement, as soon as is practicable, hydraulic control and recovery measures, which may include but shall not be limited to, recovery wells, absorbent socks, bailing, or vacuuming;
      2. (B) Identify each public or private drinking water well located on each parcel abutting the parcel on which the impacted monitoring well is located, provided that such well is within 1,000 feet of the impacted well, collect samples of water from such wells, and send for laboratory analysis as soon as is practicable but not more than 36 hours after discovery of such release;
      3. (C) 7 days after the collection of samples from a public or private drinking water well pursuant to subparagraph (B) of this subdivision, collect a second sample of water from each well tested and send for laboratory analysis;
      4. (D) Not more than 45 days after discovery of such release, prepare and submit to the commissioner an immediate action report, pursuant to subsection (k) of this section that:

8. (i) lists each drinking water well identified pursuant to subparagraph (B) of this subdivision, specifies whether each listed drinking water well has been impacted by such release, and includes the results of laboratory analysis of all samples collected from such wells;

   1. (ii) provides a schedule for the quarterly monitoring of groundwater at monitoring wells determined to be impacted by such release; and(iii) includes a description of those measures undertaken to prevent further migration of such release pursuant to subparagraph (A) of this subdivision, including a schedule for the periodic testing of wells identified pursuant to subparagraph (B) of this subdivision, and a schedule for the implementation, maintenance, and monitoring of any such measures; and(E) Notwithstanding the requirements of this subdivision, any public or private drinking water well impacted by a release shall be subject to the requirements of subdivision (1) of this subsection.

   2. (3) In addition to the actions specified by subsection (d) of this section, the following actions shall be required if a release is an emergent reportable release that is discovered in soil:

      1. (A) Not more than 2 hours after discovery of such release, initiate remediation of such impacted soil to the applicable direct exposure criteria or to the standards found in section 22a-134tt-8(a) of the RBCRs, and continue until compliance with such criteria or standards have been met; and(B) Notwithstanding the requirements of subparagraph (A) of this subsection, if such release contains PCBs, remediate or dispose of such soil in the manner required by 40 CFR 761 or as directed by the commissioner, not more than 48 hours after discovery.

   3. (4) In addition to the actions specified by subsection (d) of this section, the following actions shall be required if a release is an emergent reportable release that is a release of volatile organic substances, except volatile petroleum substances, that is discovered in groundwater within 30 feet or less of the ground surface and within 30 feet or less of the lowest portion of a building under which groundwater is impacted, or that consists of volatile petroleum substances within 10 feet or less of the ground surface and within 10 feet or less of the lowest portion of a building under which groundwater is impacted with such substances:

      1. (A) If the building is occupied or in use, immediately ventilate the building to the maximum extent practicable, which may include, but shall not be limited to, the opening of doors and windows, the use of fans, or the adjustment of the building’s air handling turnover rate;
      2. (B) All measures necessary to ensure that further migration of such release into indoor air is mitigated or prevented, which may include, but shall not be limited to:

9. (i) installation of a soil vapor extraction system;

   1. (ii) installation of a sub-slab depressurization system; or(iii) the sealing of cracks in the buildings floor and foundation or other preferential pathways; and(C) Not more than 7 days after discovery of the release, prepare and submit an immediate action plan, pursuant to subsection (j) of this section, that:

      1. (i) Describes the nature and extent of the volatile organic substances from soil or groundwater in indoor air, and includes the results of laboratory analysis of soil, soil vapor, and groundwater samples collected;
      2. (ii) Specifies a vapor mitigation system or approach to be used or installed, and a schedule for the installation of such system or approach;
      3. (iii) Includes a schedule for the maintenance and monitoring of such system or approach; and(iv) Includes a description of those measures already undertaken, or to be undertaken, to prevent further migration of such release, and a schedule for the implementation, maintenance, and monitoring of any such measures.

   2. (5) In addition to the actions specified by subsection (d) of this section, the following actions shall be required if a release is an emergent reportable release that causes a visible impact to surface water:

      1. (A) As soon as practicable, but not more than 2 hours after the discovery of such release, undertake all measures necessary to remove all impacts that are recoverable and ensure that further migration of such release is mitigated or prevented, which may include, but shall not be limited to, physical barriers such as booms, interceptor trenches, slurry walls, other physical barriers, or vacuum extraction;
      2. (B) If the release occurred in or migrated to a surface water body, each substance released is soluble or has a specific gravity greater than or equal to 1, and such release has been present in surface water for a period-of-time such that accumulation or adsorption on sediments is possible, sample sediments to determine if such sediments were impacted by the release in a reasonable time, provided such sampling shall occur not more than 48 hours following discovery of the release;
      3. (C) Not more than 45 days after discovery of such release, prepare and submit an immediate action report, pursuant to subsection (k) of this section, that includes:

10. (i) A description of measures installed to prevent migration of such release and any necessary maintenance or monitoring of such measures;

    1. (ii) The results of laboratory analysis of sediment samples if required to be collected pursuant to subparagraph (B) of this subdivision;
    2. (iii) A schedule for any necessary additional mitigation, abatement, and monitoring of the impacted surface water body; and(iv) A schedule for the quarterly monitoring of groundwater, if any groundwater is impacted by such release resulting in impacts to groundwater at a concentration greater than the surface-water protection criteria or by a nonaqueous phase liquid.

11. (f) Required Immediate Actions for a Significant Existing Release (1) In addition to the actions specified by subsection (d) of this section, the following actions shall be required if a release is a significant existing release that has impacted or is impacting a public or private drinking water well:

    1. (A) Install, as soon as is practicable, physical barriers to prevent the further migration of the release, which may include, but shall not be limited to, interceptor trenches, sheet piles or slurry walls, and implement, as soon as is practicable, hydraulic control and recovery measures, which may include but shall not be limited to, recovery wells, absorbent socks, bailing, or vacuuming;
    2. (B) Identify each public and private drinking water well located on a parcel abutting the parcel on which the impacted well is located, provided that such well is within 500 feet of the impacted well, and collect samples of water from such wells not more than 2 days after discovery of such release;
    3. (C) Ensure that an alternative source of potable water is provided to the users of each public or private drinking water well impacted by the release;
    4. (D) Not more than 15 days after discovery that a public or private drinking water well has been impacted by such release, identify each public and private drinking water well located within 200 feet of an impacted well, or within 500 feet downgradient of an impacted well; and(E) Not more than 15 days after discovery that a public or private drinking water well has been impacted by such release, prepare and submit an immediate action plan, pursuant to subsection (j) of this section, that:

12. (i) Lists each drinking water well identified pursuant to subparagraphs (B) and (D) of this subdivision, specifying whether each listed drinking water well has been impacted by such release and including the results of laboratory analysis of all samples collected pursuant to subparagraphs (B) and (D) of this subdivision;

    1. (ii) Specifies a schedule for the sampling and analysis of drinking water wells on parcels abutting the parcel on which each impacted drinking water well is located, provided each impacted drinking water well shall be sampled not less than once per quarter, and a schedule for the continued identification and sampling of potentially impacted wells in an iterative manner until all drinking water wells impacted by the release have been identified and sampled;
    2. (iii) For each drinking water well impacted by such release by a substance at a concentration greater than the groundwater protection criterion, either identifies and describes an appropriate treatment system for such substance or indicates that a connection to an unimpacted public drinking water supply system will be provided. For each treatment system identified, the plan shall specify a schedule for its installation, provided such system shall be installed not more than 15 days following discovery that such well has been impacted by such release, and any required maintenance and quarterly monitoring. For each identified connection to an unimpacted public drinking water supply system, the plan shall specify a schedule for the connection to such system, provided such connection shall be made not more than 30 days following discovery that such well has been impacted by the release;
    3. (iv) For each drinking water well impacted by such release by a substance at concentrations less than or equal to the groundwater protection criteria, and for each drinking water well within 200 feet of a drinking water well impacted by such release, provides a schedule for quarterly monitoring of such drinking water well for the substances associated with such release; and(v) Includes a description of those measures already undertaken, or to be undertaken, to prevent further migration of such release, pursuant to subparagraph (A) of this subdivision, and a schedule for the implementation, maintenance, and monitoring of any such measures.

    4. (2) In addition to the actions specified by subsection (d) of this section, the following actions shall be required if a release is a significant existing release that is of a substance for which a groundwater protection criterion has been adopted that has impacted or is impacting groundwater within 500 feet of a private or public drinking water well at a concentration greater than the groundwater protection criterion:

       1. (A) Identify each drinking water well located on a parcel abutting the parcel on which the impacted monitoring well is located, provided that such drinking water well is within 500 feet of the impacted monitoring well, and collect samples of water from such wells not more than 2 days after the discovery of such release;
       2. (B) Not more than 15 days after discovery of such release, identify each public and private drinking water well located within 200 feet of an impacted monitoring well, or within 500 feet downgradient of an impacted monitoring well;
       3. (C) As soon as practicable, implement all measures necessary to ensure that further migration of such release is mitigated or prevented;
       4. (D) Not more than 15 days after discovery of such release, prepare and submit an immediate action plan, pursuant to subsection (j) of this section, that:

13. (i) Lists each drinking water well identified pursuant to subparagraphs (A) and (B) of this subsection(ii) Specifies whether each identified well has been sampled, lists each drinking water well known to have been impacted by the release, and includes the results of laboratory analysis of all samples collected from such wells;

    1. (iii) Lists each drinking water well within 200 feet of an impacted public or private drinking water well, or within 500 feet downgradient of a groundwater monitoring well and groundwater plume exceeding groundwater protection criteria for substances associated with the release, and specifies a schedule for the sampling of such wells;
    2. (iv) Provides a schedule for the quarterly monitoring of groundwater determined to be impacted at a concentration greater than a groundwater protection criterion; and(v) Includes a description of those measures already undertaken, or to be undertaken, to prevent further migration of the release, including a schedule for the periodic testing of wells identified pursuant to subparagraphs (A) and (B) of this subdivision, and a schedule for the implementation, maintenance, and monitoring of any such measures; and(E) Notwithstanding the requirements of this subdivision, any public or private drinking water well impacted by the release shall be subject to the requirements of subdivision (1) of this subsection.

    3. (3) In addition to the actions specified by subsection (d) of this section, the following actions shall be required if a release is a significant existing release that is discovered in soil within 2 feet of the ground surface that contains a substance at concentrations at or above 30 times the industrial/commercial direct exposure criterion for such substance if the parcel is in industrial or commercial use, or at or above 15 times the industrial/commercial direct exposure criterion for antimony, arsenic, barium, beryllium, cadmium, chromium, copper, cyanide, lead, mercury, nickel, selenium, silver, thallium, vanadium, zinc or polychorinated biphenyls, excluding arsenic or lead from the lawful application of pesticides, if the parcel is in industrial or commercial use and such soil pollution is not more than 300 feet from any residence, school, park, playground or daycare facility, or at or above 15 times the residential direct exposure criterion if the parcel is in residential use:

       1. (A) Determine the location and extent of soil impacted by such release, not more than 45 days after discovery of such release;
       2. (B) Not more than 90 days after discovery of such release:

14. (i) Remove or mitigate soil within 2 feet of the ground surface impacted at concentrations greater than 15 times the applicable direct exposure criteria by measures to prevent exposure to such soil, which may include, but shall not be limited to, installation of a fence, pavement, or other temporary physical barrier;

    1. (ii) Render inaccessible, by satisfying all relevant provisions of the cleanup standards sections of the RBCRs, all soil impacted by such release at concentrations greater than the applicable direct exposure criteria;
    2. (iii) Remediate all soil impacted by such release to the applicable direct exposure criteria; or(iv) If the soil is impacted by PCBs, remediate or dispose of such soil as required by 40 CFR 761 or in a manner authorized by the commissioner or the EPA;
    3. (C) Not more than 90 days after discovery of such release, if measures to prevent exposure to such soil have been implemented pursuant to subparagraph (B)(i) or (B)(ii) of this subdivision, prepare and submit an immediate action plan, pursuant to subsection (j) of this section that:

15. (i) Describes the location and extent of such release, including the results of the laboratory analysis of samples;

    1. (ii) Includes a description and photographs of the installed measures; and(iii) Provides a schedule for the monitoring and maintenance of such measures, at a minimum annually, and sufficient to ensure that such measures remain effective; and(D) Notwithstanding the requirements of subsection (j) of this section, an immediate action plan shall not be required for a significant existing release subject to the requirements of this subdivision, if such release has been remediated to the applicable direct exposure criteria or if PCB containing soil has been remediated or disposed of in a manner authorized by the commissioner or the EPA, pursuant to subparagraph (B)(iii) or (B)(iv) of this subdivision.

    2. (4) In addition to the actions specified by subsection (d) of this section, the following actions shall be required if a release is a significant existing release that is of volatile organic substances or volatile petroleum substances to groundwater that has caused or is causing groundwater within 15 feet of an industrial or commercial building to be contaminated with a volatile organic substance at a concentration at or above 10 times the industrial/commercial volatilization criterion for groundwater for such substance or, if such contamination is within 15 feet of a residential building, at a concentration at or above 10 times the residential volatilization criterion:

       1. (A) Immediately ventilate the building to the maximum extent practicable if the building is occupied or in use; and(B) Not more than 30 days after discovery of such release, prepare and submit an immediate action plan, pursuant to subsection (j) of this section, that:

16. (i) Describes the nature and extent of such release, and includes the results of laboratory analysis of samples collected;

    1. (ii) Specifies a sufficiently protective vapor mitigation system or approach to be used or installed, which may include, but shall not be limited to, the sealing of cracks and other preferential pathways, a sub-slab depressurization system or soil vapor extraction system or an adjustment of air handling turnover rate, and a schedule for the use or installation of such system or approach;
    2. (iii) Includes a schedule for the maintenance and monitoring of such system or approach to be used or installed; and(iv) Includes a description of those measures already undertaken, or to be undertaken, to prevent further migration of such release, and a schedule for the implementation, maintenance, and monitoring of any such measures.

    3. (5) In addition to the actions specified by subsection (d) of this section, if a release is a significant existing release that is a release of a substance at a concentration greater than 10 times the surface-water protection criteria for such substance, or that is a non-aqueous phase liquid, that has impacted or is impacting groundwater within 500 feet of surface water, not more than 30 days after discovery of such release an immediate action report shall be prepared and submitted pursuant to subsection (k) of this section that:

       1. (A) Describes the nature and extent of such release, and includes the results of laboratory analysis of samples collected;
       2. (B) Identifies each measure taken to prevent migration of such release; and(C) includes a schedule for completing tier characterization of such release.

17. (g) Certification by a PEP or Verification by an LEP (1) Immediate action required by this section may be directed by the commissioner in the event such release is determined to be an emergency or exigent condition pursuant to subsection (b) of this section. If such release is not determined to be an emergency or exigent condition pursuant to subsection (b) of this section, a release record demonstrating that immediate action is complete may be certified by a PEP or verified by an LEP, except that an LEP verification shall be required if:

    1. (A) Such release was discovered or determined to be a significant existing release through laboratory analysis of samples of soil, sediment, groundwater, or indoor air;
    2. (B) Such release is causing persistent groundwater impact; or(C) The actions proposed will satisfy the standards specified in the cleanup standards sections of the RBCRs, and such cleanup standards require LEP verification.
    3. (2) The need for an LEP to verify that an immediate action is complete shall not be considered a requirement that an LEP supervise or otherwise be present at all times during an immediate action, and no time period specified in this section shall be stayed due to the presence or absence of an LEP.
    4. (3) Notwithstanding the requirements of this subsection, no person shall engage in the business of collecting, storing or treating waste oil or petroleum or chemical liquids or hazardous wastes, or of acting as a contractor to contain or remove or otherwise mitigate the effects of discharge, spillage, uncontrolled loss, seepage or filtration of such substance or material or waste, nor shall any person, municipality or regional authority dispose of waste oil or petroleum or chemical liquids or waste solid, liquid or gaseous products or hazardous wastes except in accordance with the requirements of a permit issued pursuant to section 22a-454 of the Connecticut General Statutes.

18. (h) Immediate Action Transition-Points (1) Emergent Reportable Release Transition-Points If the release for which immediate action was required is an emergent reportable release, such immediate action shall result in compliance with the standards specified at section 22a-134tt-8 of the RBCRs, the applicable numeric cleanup standard, an applicable additional polluting substances criterion calculated pursuant to section 22a-134tt-App 8 of the RBCRs, or, if such criteria cannot be met within one year of discovery, an applicable immediate action transition-point, specified below:

    1. (A) For a release impacting a drinking water well, for which required actions are specified in subsection (e)(1) of this section, such transition-points shall be:

19. (i) without treatment, 4 quarters of water monitoring laboratory analytical results that demonstrate compliance with applicable standards for each substance detected in such well;

    1. (ii) the installation of a suitable treatment system to each impacted drinking water well identified, provided that:
    2. (I) 4 quarters of water monitoring laboratory analytical results demonstrate that the substances are not detected in effluent water from the treatment system on such well as submitted to the commissioner; and(II) an immediate action report is submitted that includes all the information specified in subsection (k) of this section, a plan and schedule for the maintenance and monitoring of each treatment system installed, and the analytical results of such quarterly monitoring; or(iii) the replacement of each impacted private drinking water well identified with a connection to an unimpacted public water supply system, provided that an immediate action report is submitted that contains all the information specified in subsection (k) of this section.
    3. (B) For a release impacting groundwater, for which required actions are specified in subsection (e)(2) of this section, such transition-points shall be when, one year following discovery of the release, such release is entered into a cleanup tier requiring department oversight, and an immediate action report is submitted that contains all the information specified in subsection (k) of this section;
    4. (C) For a release impacting soil for which required actions are specified in subsection (e)(3) of this section, such transition-point shall be the removal of the release from soil to the maximum extent practicable, and the mitigation of the risk of exposure to any remaining impacted soil, provided that an immediate action report is submitted that contains all the information specified in subsection (k) of this section; and(D) For a release impacting groundwater of volatile organic substances or volatile petroleum substances for which required actions are specified in subsection (e)(4) of this section, such transition-point shall be when:

20. (i) mitigation measures identified in subsections (e)(4)(A) and (e)(4)(B) of this section have been installed or implemented and are operating but an environmental use restriction has not yet been recorded;

    1. (ii) the analysis of 9 indoor air samples, taken in consecutive months, indicates concentrations of less than or equal to target indoor air concentration calculated pursuant to section 22a-134tt-App8 of the RBCRs ; and(iii) an immediate action report is submitted that contains all the information specified in subsection (k) of this section;
    2. (E) For a release impacting surface water, for which required actions are specified in subsection (e)(5) of this section, such transition-point shall be when the release that is the source of the impact has been removed or mitigated to the maximum extent practicable and all visible sheen is collected or otherwise eliminated, provided an immediate action report is submitted that contains all the information specified in subsection (k) of this section.

    3. (2) Significant Existing Release Transition-Points If the release for which immediate action was required is a significant existing release, such immediate action shall result in compliance with the standards specified in the cleanup standards sections of the RBCRs, or an applicable immediate action transition-point, specified below:

       1. (A) For a release impacting a drinking water well, for which required actions are specified in subsection (f)(1) of this section, such transition-point shall be:

21. (i) without treatment, 4 quarters of water monitoring laboratory analytical results that demonstrate compliance with applicable standards for each substance detected in such well;

    1. (ii) the installation of a suitable treatment system to each impacted drinking water well identified, provided that:
    2. (I) 4 quarters of water monitoring laboratory analytical results demonstrate that the substances are not detected in effluent water from the treatment system on such well as submitted to the commissioner; and(II) an immediate action report is submitted that includes all the information specified in subsection (k) of this section, a plan and schedule for the maintenance and monitoring of each treatment system installed, and the analytical results of such quarterly monitoring; or(iii) the replacement of each impacted private drinking water well identified with a connection to an unimpacted public water supply system, provided that an immediate action report is submitted that contains all the information specified in subsection (k) of this section.
    3. (B) For a release impacting groundwater, for which required actions are specified in subsection (f)(2) of this section, such transition-point shall be when, one year following discovery of the release, such release is entered into a cleanup tier requiring department oversight, and an immediate action report is submitted that contains all the information specified in subsection (k) of this section.
    4. (C) For a release to soil, for which required actions are specified by subsection (f)(3) of this section, such transition-point shall be when direct exposure to such soil is mitigated, pursuant to subsection (f)(3)(B) of this section, provided an immediate action report is submitted that contains all the information specified in subsection (k) of this section;
    5. (D) For a release to groundwater of volatile organic substances or volatile petroleum substances for which required actions are specified in subsection (f)(4) of this section, such transition-point shall be when:

22. (i) mitigation measures, identified in subsection (f)(4)(B) of this section, have been installed or implemented, and are operating but an environmental use restriction has not yet been recorded;

    1. (ii) the analysis of 9 indoor air samples, taken in consecutive months, indicate concentrations of less than or equal to target indoor air concentration calculated pursuant to section 22a-134tt-App8 of the RBCRs; and(iii) an immediate action report is submitted that contains all the information specified in subsection (k) of this section; and(E) For a release to groundwater near surface water, for which required actions are specified in subsection (f)(5) of this section, tier characterization is complete and such release has been entered into a cleanup tier by filing a tier assignment and paying the required fee.

23. (i) Remediation of Remaining Substances Released (1) To the extent that the completion of the required immediate action does not result in the achievement of the standards specified in the cleanup standards sections of the RBCRs for each substance released to the land and waters of the state, a release shall remain subject to the requirement to remediate to such cleanup standards.

    1. (2) If a release remains present in the land and waters of the state following the completion of an immediate action, such release shall be:

       1. (A) Tier characterized not later than one year after discovery, pursuant to section 22a-134tt-6 of the RBCRs.
       2. (B) Assigned to a cleanup tier pursuant to the process specified in section 22a-134tt-6 of the RBCRs, except that if all substances remaining in the land and waters of the state are remediated to the standards specified in the cleanup standards sections of the RBCRs, and a release remediation closure report has been prepared that satisfies the requirements of section 22a-134tt-13 of the RBCRs, then entry into a cleanup tier shall not be required.

24. (j) Immediate Action Plan (1) The commissioner may require a person who created or is maintaining an emergent reportable release to submit an immediate action plan. The commissioner shall notify such person, verbally or in writing, that submission of an immediate action plan is required, and shall specify a deadline for the submission of such plan.

    1. (2) Any person who created or is maintaining a significant existing release, except a release to groundwater requiring immediate action pursuant to subsection (f)(5) of this section, shall submit an immediate action plan to the commissioner in the time specified by subsection (f) of this section, or, if a time period is not specified in such subsection, not more than 90 days after discovery of a significant existing release.

    2. (3) An immediate action plan shall contain a description of the actions already underway and those proposed to achieve an immediate action transition-point specified by subsection (h) of this section or a standard specified in the cleanup standards sections of the RBCRs, and shall:

       1. (A) Be prepared using a form prescribed by the commissioner;
       2. (B) Identify one or more persons who created or is maintaining the release;
       3. (C) Identify the person who will certify or verify the completion of the immediate action;
       4. (D) Reference the initial release report for such release, and update any information provided in such report based on the most current available information regarding such release;
       5. (E) Propose a schedule for achieving an immediate action transition-point specified in subsection (h) of this section or a standard specified in the cleanup standards sections of the RBCRs on or before one year following the discovery of a release;
       6. (F) Provide any other information specified by subsection (d) of this section, and subsection (e) or (f) of this section, as applicable; and(G) Provide any other information specified by the commissioner on such form.

    3. (4) The commissioner may review the immediate action plan, and may approve or reject such plan, in writing. The commissioner’s determination shall be provided to the person who submitted the immediate action plan and the person identified as certifying completion of the immediate action. If the commissioner determines that the proposed actions and schedule in such plan are not protective of human health or the environment, the commissioner shall reject the immediate action plan. If the commissioner rejects the plan, the commissioner shall state the reasons for rejection, which may include, but shall not be limited to:

       1. (A) The actions proposed are incomplete or otherwise inappropriate;
       2. (B) The schedule proposed does not address the release with sufficient urgency when considering any imminent threat to human health or the environment, even if the schedule proposed otherwise satisfies the deadlines specified in subsection (e) of this section, and subsection (f) or (g) of this section, as applicable; or(C) The immediate action plan does not identify the PEP or LEP, if an LEP is required, who will certify the immediate action is complete.
    4. (5) If the commissioner does not reject the immediate action plan within 21 days after receipt, the plan, including the proposed actions and schedule, shall be automatically deemed approved.
    5. (6) If the commissioner rejects the proposed actions and schedule, the actions and schedule shall be revised and resubmitted for the commissioner’s review not later than 7 days after such rejection.

25. (k) Immediate Action Report (1) An immediate action report shall be submitted:

    1. (A) For emergent reportable releases, on the earlier of the following:
26. (i) the assignment of such release to a tier; or(ii) the submission of a release remediation closure report; and(B) For a significant existing release, on the earlier of the following:

27. (i) A deadline specified by the commissioner in writing for the submission of such report;

    1. (ii) Not more than 60 days after completion of the actions required to achieve an immediate action transition-point specified by subsection (h) of this section or a standard specified in the cleanup standards sections of the RBCRs; or(iii) Not more than one year following discovery of an emergent reportable release or a significant existing release.

    2. (2) Such report shall:

       1. (A) Be prepared using a form prescribed by the commissioner;
       2. (B) Identify each known person who created or is maintaining the release;
       3. (C) Identify the person who, pursuant to subsection (g) of this section, supervised the immediate action;
       4. (D) Identify the immediate action transition-point specified by subsection (h) of this section, or the standards specified in the cleanup standards sections of the RBCRs that have been achieved;
       5. (E) Provide information regarding the investigation and characterization of the release sufficient to demonstrate that the transition-point or cleanup standards identified have been achieved, including confirmatory sampling of soil or groundwater, if required;
       6. (F) Identify any remaining characterization of the nature and extent of a release necessary to satisfy the requirements of section 22a-134tt-4 of the RBCRs;
       7. (G) Identify any remaining remediation required to achieve the standards specified in the cleanup standards sections of the RBCRs for any substances still present in the land and waters of the state; and(H) Provide any other information specified by the commissioner on such form.
    3. (3) If, at the time an immediate action report is submitted, the release has not been remediated to the standards specified in the cleanup standards sections of the RBCRs, the immediate action report and a tiering assignment shall be simultaneously submitted to the commissioner.

    4. (4) The commissioner may audit the immediate action report pursuant to subsection 22a-134tt-13 of the RBCRs and may approve or reject such report.

       1. (A) If the commissioner rejects the immediate action report, the commissioner may require:

28. (i) The submission of a modified report containing additional information not later than a specified deadline;

    1. (ii) The submission of a schedule for additional investigation and characterization of the release and an updated immediate action report not later than a specified deadline;
    2. (iii) The performance of additional immediate actions not later than a deadline specified by the commissioner, the submission of a schedule for the performance of such additional immediate actions, and an updated immediate action report upon completion of such actions; and(iv) the submission of a revised tiering determination.

    3. (B) Notwithstanding the provisions of subparagraph (A) of this subdivision, if any deadline to complete immediate actions specified by this section has passed, and an immediate action report has not been submitted to the commissioner, or the immediate action report submitted has been rejected, nothing in this section shall prevent the commissioner from taking any action authorized by section 22a-134ss of the Connecticut General Statutes.

       (l) Commissioner’s Authority Nothing contained in this section shall be construed to affect the authority of the Commissioner of Energy and Environmental Protection pursuant to any other statute or regulation.

(Effective March 1, 2026)