(a) Any notification of a gas leak or gas odor, or any notification of damage to facilities by contractors or other outside sources shall constitute the need for prompt action.

(b) Each operator shall be responsible for the leak investigation, classification, and repair of each leak found on its below-grade system and shall establish a means by which it determines the appropriate surveillance interval at leak locations under frost conditions.

(c) Leaks found to be on exposed piping or facilities need not be classified; however, each operator shall establish procedures for immediate elimination of potential hazards resulting therefrom.

(d) The purpose of the leak classification system is to determine the degree or extent of the potential hazard which results from gas leakage and to prescribe remedial actions therefor.

(e) Classifications shall be made only by individuals who possess training, experience, and knowledge in the field of leak classification and investigation, including extensive association with actual leakage work. The judgment of the aforementioned individuals, based upon all pertinent information and a complete leakage investigation at the scene, will form the basis for the classification.

(f) Percentages of gas-in-air included hereafter are based on natural gas. Where liquefied petroleum, manufactured or other gases are involved, appropriate adjustment shall be made as may be required, consistent with the lower explosive limit (LEL) of such gas or mixture of gases.

(g) Prior to downgrading a leak without any repair, at least one additional surveillance at the normal interval is required to verify that a lower class of hazard exists. Except for leaks downgraded to type 3 classification, which do not require a time limit for repair, if a leak is reclassified to a lower hazard level, the original date of discovery determines the time period for repair. In no case shall the time limit for required repair of any leak exceed one year from the date of discovery. This requirement does not apply to leaks classified as type 2 or 2A based on consideration of frost conditions nor to leaks, at the time of discovery, classified at a higher level pending a further, more complete investigation of the leak hazard area.

(h) When a leak is upgraded to a higher hazard level, the time period for repair is the remaining time based on its original classification or the time allowed for its new classification, whichever is less. This does not apply to leaks classified at a higher hazard level based on consideration of frost conditions nor to leaks, at the time of discovery, classified at a lower level pending a further, more complete investigation of the leak hazard area.