WAC 173-360-350   Methods of release detection for piping.  (1) Any method of release detection for piping shall meet the performance requirements of this section, with any performance claims and their manner of determination described in writing by the equipment manufacturer or installer. In addition, release detection methods, except for those methods permanently installed prior to December 22, 1990, shall be capable of detecting the leak rate or quantity specified for that method in subsection (3)(a) and (b) of this section with a probability of detection of 0.95 and a probability of false alarm of 0.05. (That is, under test conditions, a method will correctly detect at least ninety-five of one hundred actual releases, and will falsely indicate a release no more than five times in one hundred tests of nonleaking systems.)

Note:

The establishment of leak indication thresholds is a means of setting a standard for the equipment or method used. It is not in any way meant to imply that actual leak rates less than these limits are allowable. No release is acceptable, and any indication that a release may have occurred should be investigated in accordance with WAC 173-360-360.

     (2) Underground piping that routinely contains regulated substances shall be monitored for releases in a manner that meets one of the following requirements:

     (a) Pressurized piping. Underground piping that conveys regulated substances under pressure shall:

     (i) Be equipped with an automatic line leak detector conducted in accordance with subsection (3)(a) of this section; and

     (ii) Have an annual line tightness test conducted by a certified UST supervisor in accordance with subsection (3)(b) of this section or have monthly monitoring conducted in accordance with subsection (3)(c) of this section.

     (b) Suction piping. Underground piping that conveys regulated substances under suction shall either have a line tightness test conducted at least every three years beginning when release detection is required and in accordance with subsection (3)(b) of this section, or use a monthly monitoring method conducted in accordance with subsection (3)(c) of this section. No release detection is required for suction piping that is designed and constructed to meet the following standards:

     (i) The below-grade piping operates at less than atmospheric pressure;

     (ii) The below-grade piping is sloped so that the contents of the pipe will drain back into the storage tank if the suction is released;

     (iii) Only one check valve is included in each suction line;

     (iv) The check valve is located directly below and as close as practical to the suction pump; and

     (v) A method is provided that allows compliance with subsection (2)(b)(ii) through (iv) of this section to be readily determined.

     (3) Each method of release detection for piping used to meet the requirements of WAC 173-360-335 shall be conducted in accordance with the following:

     (a) Automatic line leak detectors. Methods which alert the operator to the presence of a leak by restricting or shutting off the flow of regulated substances through piping or triggering an audible or visual alarm may be used only if they detect leaks of three gallons per hour at ten pounds per square inch line pressure within one hour. An annual test of the operation of the leak detector shall be conducted in accordance with the manufacturer's requirements.

     (b) Line tightness testing. A periodic test of piping may be conducted only if it can detect a 0.1 gallon per hour leak rate at one and one-half times the operating pressure, or if it can detect a leak rate equal to multiplying 0.1 gallon per hour by the square root of the value obtained by dividing the line pressure during testing by 1.5 times the operating pressure. Line tightness testing shall be conducted and results interpreted and reported in accordance with the department's guidance document for tightness testing, or as otherwise directed by the department or delegated agency.

     (c) Applicable tank methods. Any of the methods in WAC 173-360-345 (6)(f) through (j) may be used if they are designed to detect a release from any portion of the underground piping that routinely contains regulated substances.

     (4) Certified UST supervisors who perform any of the tank services described in this section shall certify that such services comply with the requirements of this section by signing the appropriate checklist(s) provided by the department.



[Statutory Authority: Chapter 90.76 RCW. 95-04-102, § 173-360-350, filed 2/1/95, effective 3/4/95; 91-22-020 (Order 91-26), § 173-360-350, filed 10/29/91, effective 11/29/91; 90-24-017, § 173-360-350, filed 11/28/90, effective 12/29/90.]