PURPOSE: This rule describes the steps needed to verify a release.

1. (1) Unless corrective action is initiated in accordance with 10 CSR 26-2.070–10 CSR 26-2.083, owners and operators must immediately investigate and confirm all suspected releases of regulated substances requiring reporting under 10 CSR 26-2.050 within seven (7) days or another reasonable time period specified by the department using either the following steps or another procedure approved by the department:

   1. (A) System Test. Owners and operators must conduct tests appropriate for the suspected release, using tightness tests listed by the National Work Group on Leak Detection Evaluations and/or approved by the department, or for containment sumps, a test method included in 10 CSR 26-2.035, to determine whether a leak exists in that portion of the tank system that routinely contains a regulated substance or a breach of the interstitial space has occurred. To obtain copies of equipment listings, contact the National Work Group on Leak Detection Evaluations, www.nwglde.org.

      1. 1. If the system test confirms a leak into

the interstice or a release, owners and operators must repair, replace, upgrade, or close the underground storage tank (UST) system. Owners and operators must conduct a site check and comply with subsection (l)(B) if the test results for the system, tank, or delivery piping indicate that a release has occurred.

1. 2. Further investigation is not required if

the test results for the system, tank, and delivery piping do not indicate that a release exists and if environmental contamination is not the basis for suspecting a release.

1. 3. Owners and operators must conduct a

site check as described in subsection (1)(B) of this rule if the test results for the system, tank, and delivery piping do not indicate that a leak exists but environmental contamination is the basis for suspecting a release; or

1. (B) Site Check. Owners and operators must measure for the presence of a release where contamination is most likely to be present at the UST site. In selecting sample types, sample locations, and measurement methods, owners and operators must consider the nature of the stored substance, the type of initial alarm or cause for suspicion, the type of backfill, the depth of groundwater, and other factors appropriate for identifying the presence and source of the release.

   1. 1. If the site check indicates that a

release has occurred, owners and operators must begin site characterization and corrective action in accordance with 10 CSR 26- 2.070–10 CSR 26-2.083; or

1. 2. If the results of the site check do not

indicate that a release has occurred, the investigation may stop.

1. (2) Owners and operators shall follow a written procedure. A copy of the written procedure or, if the written procedure is commonly available, a clear reference to the written procedure shall be submitted to and approved by the department prior to beginning activities required by this rule.

AUTHORITY: sections 319.105, 319.107, 319.109, and 319.137, RSMo 2016.* This rule originally filed as 10 CSR 20-10.052. Original rule filed April 2, 1990, effective Sept. 28, 1990. Amended: Filed Aug. 3, 1993, effective April 9, 1994. Moved and amended: Filed April 15, 2011, effective Dec. 30, 2011. Amended: Filed Aug. 15, 2016, effective May 30, 2017. *Original authority: 319.105, RSMo 1989; 319.107, RSMo 1989, amended 1994; 319.109, RSMo 1989, amended 1995, 2004, 2008; and 319.137, RSMo 1989, amended 1993, 1995, 2004.