Owners and operators of hazardous substance UST systems shall provide release detection that meets the following requirements:
(1) Release detection at existing hazardous substance UST systems shall meet the requirements for petroleum UST systems in WAC 173-360-335
. By December 22, 1998, all existing hazardous substance UST systems shall meet the release detection requirements for new systems in subsection (2) of this section.
(2) Release detection at new hazardous substance UST systems shall employ some method of release containment such as secondary containment systems, double-walled tanks, or external liners (e.g., in a pit or excavation). Such methods shall meet the following requirements:
(a) Secondary containment systems shall be designed, constructed and installed to:
(i) Contain regulated substances released from the tank system until they are detected and removed;
(ii) Prevent precipitation and groundwater from entering the external liner and prevent the release of regulated substances to the environment at any time during the operational life of the UST system; and
(iii) Be checked for evidence of a release at least every thirty days.
The provisions of 40 C.F.R. 265.193, Containment and Detection of Releases, may be used to comply with these requirements.
(b) Double-walled tanks shall be designed, constructed, and installed to:
(i) Contain a release from any portion of the inner tank within the outer wall; and
(ii) Detect the failure of the inner wall.
(c) External liners (including vaults) shall be designed, constructed, and installed to:
(i) Contain one hundred ten percent of the capacity of the largest tank within its boundary;
(ii) Prevent the interference of precipitation or ground-water intrusion with the ability to contain or detect a release of regulated substances; and
(iii) Surround the tank completely (i.e., it is capable of preventing lateral as well as vertical migration of regulated substances).
(d) Underground piping shall be equipped with secondary containment that satisfies the requirements of subsection (2)(a) of this section (e.g., trench liners, jacketing double-walled pipe). In addition, underground piping that conveys regulated substances under pressure shall be equipped with an automatic line leak detector in accordance with WAC 173-360-350
(e) Other methods of release detection may be used if owners and operators:
(i) Demonstrate to the department or delegated agency that an alternate method can detect a release of the stored substance as effectively as any of the methods allowed in WAC 173-360-345
(6)(b) through (j) can detect a release of petroleum;
(ii) Provide information to the department or delegated agency on effective corrective action technologies, health risks, and chemical and physical properties of the stored substance, and the characteristics of the UST site; and
(iii) Obtain approval from the department or delegated agency to use the alternate release detection method before the installation and operation of the new UST system.
[Statutory Authority: Chapter 90.76
RCW. WSR 95-04-102, § 173-360-340, filed 2/1/95, effective 3/4/95; WSR 90-24-017, § 173-360-340, filed 11/28/90, effective 12/29/90.]