(a) Each operator of a distribution system shall provide for periodic leakage surveys in its operating and maintenance plan. Leaks located by these surveys shall be investigated promptly and necessary action shall be taken in accordance with sections 255.805 and 255.807 of this Part.
(b) The type and scope of the leakage control program must be determined by the nature of the operations and the local conditions, but it must meet the following minimum requirements:
(1) A leakage survey with leak detector equipment shall be conducted at intervals not exceeding 15 months, but at least once each calendar year, in business districts within the operator's gas franchise area including tests of the atmosphere of gas, electric, telephone, sewer, and water system manholes, at cracks in pavement, at the curbline, in the sidewalk, and at other locations providing an opportunity for finding gas leaks.
(2) Leakage surveys of the distribution system outside of business districts, must be made as frequently as necessary, but at least once every five calendar years at intervals not exceeding 63 months.
(3) If the operator employs leakage history to determine areas of active corrosion, the leakage survey frequency shall be at least once every three calendar years at intervals not exceeding 39 months on mains and service lines.
(c) Distribution lines operating at 125 psig (862 kPa) or more and located in Class 3 and 4 locations must comply with the transmission line leakage survey requirements in section 255.706 of this Part.