DOMINION ENERGY QUESTAR PIPELINE, LLC

Incident Narrative

ON 11/17/2018 AT 18:26 LOCAL TIME, DOMINION ENERGY QUESTAR PIPELINE'S (DEQP) MAIN LINE 048 (ML048) RUPTURED IN RICH COUNTY, UT. OPERATORS WERE DISPATCHED AND SHUTDOWN THE ML048 TRANSMISSION PIPELINE VIA MANUAL BLOCK VALVES AT 19:47. AT 20:12, A DEQP OPERATOR ARRIVED ON-SITE OF THE INCIDENT AND DISCOVERED A RUPTURE OF THE 20"" ML048 PIPELINE WHICH HAD RESULTED IN AN UNINTENDED NATURAL GAS LOSS OF APPROXIMATELY 48.9 MMSCF. ONCE IT WAS CONFIRMED AT 20:48 THAT THE INCIDENT WAS REPORTABLE, INCLUDING CONFIRMATION OF EXACT FAILURE LOCATION, DEQP NOTIFIED THE NATIONAL RESPONSE CENTER VIA TELEPHONIC REPORT ON 11/17/2018 AT 20:53. A 48-HOUR CONFIRMATION OF THE INCIDENT WAS REPORTED TO THE NRC ON 11/19/2018 AT 17:56. AN INCIDENT INVESTIGATION TEAM WAS DEPLOYED AND PROGRESSED AN INVESTIGATION OF THE FAILURE AND REPAIR OF THE PIPELINE. CAUSE OF THE FAILURE WAS EXTERNAL CORROSION AS A RESULT OF DISBONDED COATING AND CP SHIELDING AS DETERMINED BY A KIEFNER & ASSOCIATES METALLURGICAL ANALYSIS. NOTES ON PARTICULAR QUESTIONS PART A: Q 6-7. SECOND NRC NOTIFICATION NUMBER 1230856 ON 11/19/2018 AT 17:56 LOCAL TIME Q 15B. COMPANY REPAIRED THE PIPELINE SEGMENT DIRECTLY AFFECTED BY THE FAILURE AND PLACED THE SEGMENT BACK IN-SERVICE SUBJECT TO SEVERAL COMMITMENTS: 1) MAINTAIN A PIPELINE PRESSURE AT 80% OF OPERATING PRESSURE AT TIME OF FAILURE, 2) CONTRACT WITH INDEPENDENT PARTY AND COMPLETE A PIPE FAILURE ANALYSIS, 3) COMPLETE INLINE INSPECTION OF MAIN LINE 048 FROM YELLOW CREEK SITE TO THE MAIN LINE 048-MAIN LINE 060 JUNCTION, AND 4) PERFORM NECESSARY REMEDIATION. THE PIPE FAILURE ANALYSIS HAS BEEN COMPLETED BY KIEFNER AND ASSOCIATES. INLINE INSPECTION IS IN PROGRESS AT THE TIME/DATE OF THIS SUPPLEMENTAL REPORT, AND THE PIPELINE REMAINS UNDER THE OPERATING RESTRICTION COMMITMENT (80% OF OPERATING PRESSURE AT TIME OF FAILURE). Q 19A. TIME ENTERED REFERS TO TIME OPERATOR BECAME AWARE OF INCIDENT BUT HAD NOT CONFIRMED