1. (a) Discovery of an Existing Release (1) Discovery of a release to the land and waters of the state occurs when a person who created or is maintaining an existing release has knowledge of such release, except that a release shall not be deemed discovered if the only evidence of such release is data available or generated before the date the RBCRs are adopted.

   1. (2) Provided a substance is not present because it has been authorized under Title 22a of the Connecticut General Statutes, is naturally occurring, or is a result of automotive exhaust or the application of fertilizer or pesticides consistent with their labeling, a person who created or is maintaining a release has knowledge of a release if such person:

      1. (A) Becomes aware of the results of laboratory analysis of soil, groundwater, sediment, or soil vapor that indicate concentrations of such substances above the laboratory reporting limit;
      2. (B) Becomes aware of the observed presence of non-aqueous phase liquid; or(C) (i) When, in the course of an investigation, taking into account any specialized knowledge or training, becomes aware of multiple lines of evidence that would indicate to a reasonable person, with similar knowledge, experience or training, exercising a degree of care that a reasonable person would exercise in the same or similar circumstances, the presence of a release in or on the land and waters of the state. Such lines of evidence may include, but shall not be limited to:

      3. (I) information about the use of a particular geographic area, including anecdotal reports of historical disposal or releases, aerial photographs, and maps;

         1. (II) the results of field screening indicating the presence of volatile organic compounds, petroleum hydrocarbons, or metals;
         2. (III) observed staining of soil, concrete floors, or pits;
         3. (IV) organoleptic evidence, including odors;
      4. (V) indoor air samples indicating the intrusion of soil vapors; or(VI) the observed presence of asphalt, coal slag, solid waste, ash, or other non-native materials in or on the land and waters of the state;
   2. (3) For the purposes of this subsection data available or generated before the date when the RBCRs are adopted shall encompass environmental reports or investigations conducted prior to the date when the RBCRs are adopted, including but not limited to, laboratory analytical data and observations, photographs or research regarding the historical use of an area of land.
   3. (4) Notwithstanding the requirements of this subsection, a significant environmental hazard reported to the commissioner pursuant to section 22a-6u of the Connecticut General Statutes that is in compliance with the requirements of that section shall not be deemed discovered until 2 years after the effective date of the RBCRs.
2. (b) Existing Releases Discovered by Other Persons If characterization of an existing release performed pursuant to the requirements of section 22a-134tt-4 of the RBCRs has identified the source of such release, and information regarding such characterization, indicating concentrations of such substances above the laboratory reporting limit, is provided to any person who would be considered to have created or be maintaining a release by the person performing such characterization, the person who receives such notice shall be presumed to have created or be maintaining a release. Such presumption may be rebutted through characterization of the area from which such release is believed to be emanating.
3. (c) Discovery of a Significant Existing Release In addition to the provisions of subsection (a) of this section, a significant existing release is discovered when any person obtains knowledge of a significant existing release.
4. (d) Releases from Regulated Underground Storage Tank Systems If the source of a release is or was an underground storage tank system regulated by the underground storage tank system regulations adopted pursuant to section 22a-449(d) of the Connecticut General Statutes, such release shall not be considered to have been discovered for the purposes of the RBCRs.

5. (e) Discovery of Emergent Reportable Releases (1) Any release to the land and waters of the state required to be reported by regulations adopted pursuant to section 22a-450 of the Connecticut General Statutes shall be considered to be discovered and shall be subject to the requirements of the RBCRs, unless otherwise exempted from discovery by subsection (d) of this section.

   1. (2) Releases required to be reported by regulations adopted pursuant to section 22a-450 of the Connecticut General Statutes shall be deemed not to be releases to the land and waters of the state, and shall not be subject to the requirements of the RBCRs, if:

      1. (A) The release occurs to the air;
      2. (B) The release occurs to a secondary containment system entirely within the interior of a structure or to a secondary containment system outside the interior of a structure that does not contact soil, such as an aboveground storage tank; or(C) The release occurs to the interior of a structure and does not come into contact with soil; and substantially all of the material released is removed from any surface to which it was released not more than 2 hours after discovery.

6. (f) Naturally Occurring Metals at the Time of Discovery (1) If the laboratory analytical results of soil samples identify the presence of one or more metals listed in the following table, each metal shall be considered naturally occurring if:

   1. (A) The concentration of such metal in each sample analyzed is less than or equal to the low value listed in the following table that corresponds to such metal;
   2. (B) Not less than 3 samples of soil have been analyzed and the concentration in any one or more samples analyzed of a metal other than beryllium or silver is greater than the low value listed in the following table that corresponds to such metal but the concentration in each sample analyzed is less than or equal to the high value in the following table that corresponds to such metal;
   3. (C) Not less than 5 samples of soil have been analyzed and the concentration in any one or more samples analyzed is greater than the high value listed in the following table that corresponds to such metal but the concentration in each sample analyzed is less than or equal to the residential direct exposure criteria for such metal, provided an outlier analysis has been performed and any sample determined to be an outlier is evaluated to determine whether such sample has resulted in the discovery of a release;
   4. (D) Not less than 7 samples of soil have been analyzed and the concentration in any one or more samples analyzed is greater than the residential direct exposure criteria for such metal, provided an outlier analysis has been performed and the results of the laboratory analysis of all soil samples analyzed is provided to the commissioner, and the commissioner determines in writing that the identified metal is naturally occurring; or(E) The identified metal is determined to be background using a method other than the methods specified in this subsection, provided such method is submitted to the commissioner in writing and the commissioner approves of the use of such method.

   5. (2) For the purposes of determining background concentrations pursuant to subdivision (1) of this subsection, soil samples shall be collected and analyzed as follows:

      1. (A) If one or more samples identify concentrations of metals greater than the low value listed in the following table, the minimum number of samples of soil specified by subparagraphs (B), (C), and (D) of this subdivision shall be collected from another area reasonably believed not to be impacted by site activity, and shall be from the same geologic unit and of similar texture and composition;
      2. (B) If one or more samples identifying concentrations of metals greater than the low value listed in the following table have been collected from a known or suspected release area, the minimum required number of samples of soil specified by subparagraphs (B), (C), or (D) of this subdivision shall be collected from outside such known or suspected release area; and(C) All analytical data shall comply with the requirements of section 22a-134tt-1(d) of the RBCRs. If an outlier analysis is required, such analysis shall be performed pursuant to any method specified by the commissioner pursuant to section 22a-134tt-1(d) of the RBCRs or another method approved by the commissioner pursuant to such section. Naturally Occurring Background Metals Values for ConnecticutInorganic SubstanceLow Value in mg/kg (ppm)High Value in mg/kg (ppm)Aluminum58,80085,040Antimony0.10.3Arsenic36Barium385756Beryllium22Bismuth0.20.5CadmiumND < 0.10.3Calcium5,61020,870Cerium73138CesiumND < 58Chromium3160Cobalt920Copper1745Gallium1524Indium0.050.1Iron26,08051,940Lanthanum3266Lead1827Lithium2060Magnesium5,84015,320Manganese5441,195Mercury0.030.1Molybdenum0.74Nickel1336Niobium1017Phosphorus339817Potassium16,93029,620Rubidium80117Scandium1218SeleniumND < 0.20.8SilverND < 1ND < 1Sodium9,93018,500Strontium125283SulfurND < 100304Thallium0.40.8Thorium1115Tin23Titanium2,8804,660Tungsten0.92Uranium37Vanadium69102Yttrium1931Zinc44104Notes:ND = non-detect at the specified reporting limitmg/kg = milligrams per kilogram

(Effective March 1, 2026)