WAC 173-360-340
Release detection for hazardous
substance UST systems. 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.
Note:
The provisions of 40 CFR 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 (3)(a).
(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.