Owners and operators of UST systems with containment sumps used for interstitial monitoring of piping must comply with the requirements of this section and the walkthrough inspection requirements in WAC 173-360A-0420 to ensure the equipment is operating properly and will prevent releases to the environment.

(1) Periodic monitoring or testing. Containment sumps used for interstitial monitoring of piping must meet one of the following requirements:

(a) The containment sump is double-walled and the integrity of both walls is monitored at least annually as part of the walkthrough inspection in WAC 173-360A-0420 (1)(b)(i)(C). If monitoring is discontinued, the containment sump must be tightness tested in accordance with (b) of this subsection within thirty days; or

(b) The containment sump is tightness tested at least every three years to ensure it is liquid tight. The tightness test must be performed:

(i) By or under the direct supervision of a service provider certified in accordance with Part 9 of this chapter; and

(ii) Using a vacuum, pressure, or liquid test (including a low level liquid test) performed in accordance with:

(A) The manufacturer's instructions;

(B) A code of practice. The following code of practice may be used to meet this requirement: Petroleum Equipment Institute, Recommended Practice 1200, "Recommended Practices for the Testing and Verification of Spill, Overfill, Leak Detection and Secondary Containment Equipment at UST Facilities"; or

(C) Requirements determined by the department to be no less protective of human health and the environment.

(2) Repairs. Containment sumps that are not operating properly must be repaired in accordance with WAC 173-360A-0490 or replaced in accordance with WAC 173-360A-0300.

(3) Reporting. Tightness tests of containment sumps must be reported to the department within thirty days using the applicable checklist provided by the department. The checklist must be completed by the service provider.

(4) Recordkeeping.

(a) Records of periodic monitoring of containment sumps must be maintained for at least three years. The records must demonstrate that the sumps are double-walled and the integrity of both walls is periodically monitored.

(b) Records of tightness tests of containment sumps must be maintained for at least six years.

(5) Compliance dates. The periodic monitoring or tightness testing of containment sumps required under this section must begin by the following dates:

(a) For UST systems installed after October 1, 2018, upon installation; and

(b) For UST systems installed on or before October 1, 2018:

(i) If the UST facility has an even facility compliance tag identification number, by October 1, 2020; and

(ii) If the UST facility has an odd facility compliance tag identification number or does not have a facility compliance tag, by October 1, 2021.