This final rule establIshes procedures to be followed in the operation and maintenance (O&M) of gas pipeline facilities. This action amends current standards by requiring regulated gas pipeline operators to include detailed procedures regarding normal and abnormal operation; maintenance and emergency-response activities in their O&M manual. Furthermore. operators are required to review and update their O&M manual each calendar year. Finally. this final rule requires that regulated gas and hazardous liquid pipeline operators prepare and follow procedures to safeguard personnel from the hazards. associated with the unsafe accUmulation of vapor or gas in excavated trenches.