COLUMBIA GAS TRANSMISSION, LLC

Incident Narrative

PIPELINE 134 IS A 10-INCH BARE CARBON-STEEL PIPELINE OWNED AND OPERATED BY COLUMBIA GAS TRANSMISSION, LLC (OPID 2616), A TC ENERGY ENTITY. THIS SEGMENT OF LINE 134 IS MECHANICALLY COUPLED, PLACED INTO SERVICE IN 1929 WITH A MAXIMUM ALLOWABLE OPERATING PRESSURE OF 250 PSIG. ON AUGUST 21, 2019 LINE 134 WAS SUBJECT TO A MECHANICAL COUPLING FAILURE OCCURRING IN ARMSTRONG COUNTY, PENNSYLVANIA. THE MORNING OF AUGUST 21ST, GAS CONTROL RECEIVED AN ALARM FROM THE IOWA COMPRESSOR STATION INDICATING THAT UNIT 1 HAD HIGH DISCHARGE PRESSURE. STATION PERSONNEL WERE DISPATCHED AND RESPONDED TO THIS CALL. LATER THAT HOUR GAS CONTROL RECEIVED A SECOND ALARM FROM THE IOWA COMPRESSOR STATION INDICATING THAT UNIT 2 HAD LOW SUCTION PRESSURE. THIS CALL WAS ALSO RESPONDED TO AND EVALUATED. PIPELINE PRESSURE CONTINUED TO DROP. OPERATIONS MANAGERS WERE NOTIFIED, AND ADDITIONAL SUPPORTING COMPANY PERSONNEL WERE DISPATCHED. THE PIPELINE LEAK WAS LOCATED AND ISOLATED BY 7:58 AM. THE PIPELINE IN THIS AREA IS PART OF A MODERNIZATION PROJECT. AT THE TIME OF THE INCIDENT, THE EFFECTED SEGMENT OF LINE 134 IN THIS PROJECT HAD BEEN EXPOSED, STOPPLES INSTALLED, PIPELINE SECTIONS REMOVED, AND END CAPS WERE INSTALLED. THE CONSTRUCTION ACTIVITIES DURING THIS CONSTRUCTION WORK APPEAR TO HAVE CONTRIBUTED TO THE DISCONNECTION OF THIS SECTION OF PIPE. INITIAL NRC REPORT NUMBER IS 1255871 REPORTED AUGUST 21, 2019 AND THE 48-HOUR NRC REPORT NUMBER IS 1256125 REPORTED ON AUGUST 23, 2019. THE INTERNAL INVESTIGATION INTO THIS INCIDENT HAS DETERMINED THE FOLLOWING CAUSAL FACTORS: -GUIDELINES FOR THE USE OF MECHANICAL COUPLINGS RESIDED WITHIN CPG INTEGRATED DOCUMENTS LISTING BUT NOT WITHIN THE TC ENERGY CONTROLLED DOCUMENT LIBRARY; THE SINGLE REFERENCE SOURCE FOR US NATURAL GAS PIPELINES PROJECTS. -DURING PROJECT PLANNING THE RISKS OF EXCAVATION ON 1929 VINTAGE PIPELINE SYSTEM WITH PROBABILITY FOR MECHANICAL COUPLINGS WAS NOT DOCUMENTED AS A POTENTIAL HAZARD FOR EXCAVATION/CONSTRUCTION ACTIVITIES. -WHEN A MECHANICAL COUPLING WAS EXPOSED DURING EXCAVATION, THE RISK WAS NOT ADEQUATELY ESCALATED BY THE CONTRACTOR TO THE PROJECT MANAGER. ADDITIONALLY, THE DECISION TO MOVE THE STOPPLE INSTALLATION POINT DUE TO MECHANICAL COUPLING DISCOVERY AT THAT POINT DID NOT GENERATE DISCUSSION ON THE RISK OF THE EXPOSED MECHANICAL COUPLING OR THE POTENTIAL OF ADDITIONAL MECHANICAL COUPLINGS NEAR THE EXCAVATION SITE. CORRECTIVE ACTIONS COMPLETED TO DATE INCLUDE: -ESTABLISHED US NATURAL GAS PROJECTS INITIATIVE TO IDENTIFY GAPS IN EXISTING ENGINEERING DESIGN STANDARDS -REQUIRE ALL PROJECTS TO DEVELOP A PRE-JOB SAFETY MANAGEMENT PLAN -THE DISTRIBUTION OF THE ""MECHANICAL PIPELINE REPAIR TAPPING AND JOINING"" PROCEDURE TO US NATURAL GAS PROJECT, US CONSTRUCTION SERVICES STAFF, US GAS OPERATIONS FIELD OPERATIONS MANAGERS AND TEAM LEADERS -PUBLICATION OF THE ""MECHANICAL PIPELINE REPAIR TAPPING AND JOINING"" PROCEDURE TO THE CONTROLLED DOCUMENT LIBRARY -ESTABLISHED REQUIRED TRAINING FOR US NATURAL GAS PROJECT CONSTRUCTION MANAGERS AND US GAS OPERATIONS FIELD OPERATIONS STAFF ON ""MECHANICAL PIPELINE REPAIR TAPPING AND JOINING"" PROCEDURES. -DISTRIBUTED LESSONS LEARNED SAFETY SHARE TO US NATURAL GAS PIPELINES PROJECTS, CONSTRUCTION SERVICES AND US GAS OPERATIONS FIELD OPERATIONS. -ADDITIONAL TRAINING PLANNED IN 2021