NORTHERN NATURAL GAS CO

Incident Narrative

AT 15:19 ON DECEMBER 24, 2020, NORTHERN NATURAL GAS RECEIVED NOTIFICATION FROM THE LYONS NE VOLUNTEER FIRE DEPARTMENT OF A PIPELINE RUPTURE SOUTH OF COUNTY ROAD P IN BURT COUNTY, NEBRASKA. THE RUPTURED LINE WAS IDENTIFIED AS THE 179NEM50103-M570C HOOPER TO SOUTH SIOUX CITY C-MAINLINE AT MILEPOST 21.32. THIS LOCATION IS 3.8 MILES SOUTH OF THE NEB56001 LYONS, NEBRASKA BRANCH LINE TAKE-OFF. OPERATIONS STAFF ISOLATED THE RUPTURED SEGMENT AT 16:46 HOURS AFTER 8.18 MILLION CUBIC FEET OF GAS LOSS. INITIAL OBSERVATIONS BY THE FIELD INVESTIGATION TEAM INDICATED THE FAILURE MAY HAVE BEEN CAUSED BY PREVIOUS THIRD PARTY DAMAGE. THE FIELD INVESTIGATION TEAM IDENTIFIED A SERIES OF GOUGES AND SCORES ACROSS A SEGMENT OF PIPE WHICH WAS FOUND ABOUT 100 YARDS SOUTH OF THE FAILURE SITE. THE ROOT CAUSES OF THIS EVENT ARE A THIRD PARTY CONTRACTOR COMMENCING EXCAVATION PRIOR TO THE CLEARING OF A ONE CALL TICKET. THERE WERE TWO ONE CALL TICKETS REGARDING THIS PROPERTY. ONE FOR OCT 30 TO CLEAR TREES AND REMOVE TERRACES AND ONE FROM DEC 4 TO BURY LEFT OVER DEBRIS FROM A BURN PILE. THE DAMAGE TO THE PIPELINE PROBABLY OCCURRED AT THE OCT 30 WORK. A CONTRIBUTING FACTOR WAS A FIELD OPERATIONS FAILURE TO FOLLOW NORTHERN PROCEDURE BY GIVING VERBAL APPROVAL FOR EXCAVATION ACTIVITIES IN PROXIMITY TO A PIPELINE BEGIN BEFORE THE EMPLOYEE ARRIVED ON SITE. BOTH TIMES THE ONE CALL TICKETS WERE COMPLETED BY THE SAME EMPLOYEE AND THE PIPELINES MARKED IN ACCORDANCE WITH COMPANY PROCEDURES. THE EMPLOYEE REMAINED ON SITE UNTIL ALL WORK WAS COMPLETED. NORTHERN NATURAL GAS MOBILIZED THE EMERGENCY RESPONSE TEAM AND CONSTRUCTION RESOURCES TO THE INCIDENT SITE AND COMPLETED REPAIRS AT 22:29 HOURS DECEMBER 25, 2020.