33.1-13-01-05. Release detection requirements for aboveground storage tank piping.

An owner or operator shall provide the following release detection for piping:

1. Aboveground piping. An owner or operator shall: a. Visually inspect and document leaks and seepage at least monthly; and b. Repair any areas of the piping, including pipe joints, that show visible seepage.

2. Underground piping. Release detection for new underground piping of an aboveground storage tank system must meet the following requirements: a. Any new piping system must be secondarily contained. b. The interstitial space between the inner and outer pipe walls must drain to a containment sump.

c. Underground piping must be monitored for leaks through one of the following:

(1) A piping system that is pressurized using a pump or is under any other type of pressure more than normal head pressure of the aboveground storage tank, must be equipped with:

(a) An electronic line leak detector and a positive shutoff normally closed solenoid valve. A method which alerts the operator to the presence of a leak by shutting off the flow of liquid fuel through piping and triggering an audible or visual alarm. May be used only if they continuously detect leaks of three gallons [11.36 liters] per hour at ten pounds per square inch [68.95 kilopascals] line pressure within one hour; and

(b) Secondary containment monitored for releases by one of the following methods:

[1] Continuous interstitial monitoring between the inner and outer barriers of underground piping may be used if the system is designed, constructed, and installed to detect a leak from any portion of the piping that routinely contains liquid fuel. All transition, dispenser, and other sumps must be equipped with liquid sensing float sensors that trigger an audible or visual alarm and shut-off the flow of liquid fuel through all buried piping and the inner wall in any portion of the piping that routinely contains liquid fuel; or

[2] The department may approve another method of release detection if the owner and operator can demonstrate that the method, or combination of methods, can detect a two-tenths gallon [.76 liter] per hour leak rate or a release of one hundred fifty gallons [567.81 liters] within a month with a probability of detection of ninety-five percent and a probability of false alarm of five percent. In comparing methods, the department shall consider the size of release the method can detect and the frequency and reliability with which it can be detected. If the method is approved, the owner or operator shall comply with any department imposed conditions imposed by the department on its use to ensure the protection of human health and the environment.

(2) A piping system with no more than normal head pressure from the aboveground storage tank system must be continuously monitored for releases by interstitial monitoring. Interstitial monitoring between the underground piping and a secondary containment barrier immediately around it may be used, if the system is designed, constructed, and installed to detect a leak from any portion of the piping that routinely contains product, and the sampling or testing method can detect a leak through the inner wall in any portion of the piping that routinely contains product. The piping system must have a positive shutoff normally closed solenoid valve installed before any buried piping. All transition, dispenser, and other sumps must be equipped with liquid sensing float sensors that trigger an audible or visual alarm and shut off the flow of liquid fuel through all buried piping.

d. Release detection for existing underground piping must monitor for leaks through at least one of the following:

(1) A piping system that is pressurized using a pump or any other type of underground piping system that is under more than normal head pressure of the aboveground storage tank system, which must meet one of the following requirements:

1. (a) The piping system is secondarily contained and meets the release detection requirements for new double-walled piping in subsection 2; or
2. (b) The piping system is single walled and meets the release detection requirements for electronic line leak detectors in subparagraph a of paragraph 1 of subdivision c, in compliance with subsection 6 of section 33.1-13-01-02 and passes a yearly line tightness test that meets the release detection requirements of subparagraph b of paragraph 1 of subdivision c. The initial line test shall be performed within one year of the effective date of this chapter. A positive shutoff normally closed solenoid valve must be installed before any buried piping.(2) A piping system with no more than normal head pressure from the aboveground storage tank system, which must be continuously monitored for releases by interstitial monitoring. Interstitial monitoring between the underground piping and a secondary containment barrier immediately around it may be used, if the system is designed, constructed, and installed to detect a leak from any portion of the piping that routinely contains product, and the sampling or testing method can detect a leak through the inner wall in any portion of the piping that routinely contains product. The piping system must have a positive shutoff normally closed solenoid valve installed before any buried piping. All transition, dispenser, and other sumps must be equipped with liquid sensing float sensors that trigger an audible or visual alarm and shut off the flow of liquid fuel through all buried piping. Existing single-walled suction type systems must be converted to a pressurized system to comply with the requirements outlined in paragraph 1.(3) Applicable tank methods. Any of the methods in this section may be used for release detection if it is designed to detect a release from any portion of the underground piping that routinely contains liquid fuel.3. Annual testing. An owner or operator shall conduct an annual test of the electronic line leak detection systems and, when installed, sump alarm systems to test for proper operation, in accordance with one of the following:- a. Manufacturer's instructions;
3. b. A code of practice developed by a nationally recognized association or independent testing laboratory; or
4. c. Requirements determined by the department to be no less protective of human health and the environment than subsection 1 or 2.4. Annual line tightness tests. All underground piping systems from the aboveground storage tank system must conduct an annual test of piping that can detect a one-tenth gallon [0.38 liter] per hour leak rate at one and one-half times the operating pressure. The initial line test must be performed before October 1, 2026.5. A normally closed solenoid valve, which must be installed at the connection between the tank and piping to eliminate continuous head pressure on the piping, by April 1, 2027, if not already installed.