NORTHWEST PIPELINE LLC

Incident Narrative

THIS INCIDENT IS RELATED TO CORROSION FEATURES ASSOCIATED WITH PRIOR INCIDENT NO. 20200073-34025. IT IS SUBMITTED SEPARATELY DUE TO THE TIME ELAPSED BETWEEN DISCOVERY OF THE INITIAL THROUGH WALL ANOMALIES AND THIS ADDITIONAL THROUGH WALL ANOMALY. AT THE TIME OF DISCOVERY, THE LINE WAS ISOLATED AND BLOWN DOWN DUE TO MAINTENANCE WORK ON THE OTHER FEATURES IDENTIFIED THROUGH IN-LINE INSPECTION. IN APRIL OF 2020 WILLIAMS CONTRACTED WITH AN IN-LINE INSPECTION VENDOR TO COMPLETE TOOL RUNS ON THE WILLIAMS NORTHWEST PIPELINE 1400 POCATELLO TO BURLEY SEGMENT. HIGH-RES MFL TOOL RUNS WERE CONDUCTED, AND A PRELIMINARY REPORT WAS PROVIDED TO WILLIAMS WITH CERTAIN HIGH-PRIORITY ANOMALIES ON THE WEEK OF 5/25/2020. A PROJECT WAS INITIATED TO ADDRESS PRELIMINARY HIGH-PRIORITY ANOMALIES. IN PREPARATION TO EXCAVATE, WILLIAMS OPERATIONS CONDUCTED A LEAK SURVEY OF THE EXCAVATION AREA AND IDENTIFIED GAS READINGS AT THREE ANOMALIES WITHIN AN APPROXIMATE 350FT. SPAN ON 6/10/2020 NEAR M.P. 626.8. IN RESPONSE, THE LINE SEGMENT BETWEEN VALVES 9-1 AND 9-2 WAS SHUT-IN AND BLOWN DOWN ON THE SAME DATE. EXCAVATIONS OF THE ANOMALIES CONFIRMED PIN-HOLE LEAKS RESULTING FROM CORROSION. AFTER ASSESSING REPAIR OPTIONS WILLIAMS PROJECT MANAGEMENT DETERMINED THAT REPAIRS WOULD BE BEST ACCOMPLISHED THROUGH PIPE REPLACEMENT OF THE AFFECTED AREAS. THE PRELIMINARY COST OF REPAIRS EXCEEDS $50,000, WITH COST OF CONTRACTOR AND INTERNAL LABOR APPROACHING $200,000 PER FEATURE. IT WAS DETERMINED THAT THIS QUALIFIED AS A DOT REPORT-ABLE INCIDENT BASED ON COST. THE NRC WAS INITIALLY NOTIFIED OF THE INCIDENT ON 6/16/2020. AT THE TIME OF THIS REPORT THE LINE IS SHUT-IN AND BLOWN-DOWN. AS OF THE DATE OF THIS REPORT, CUT-OUTS/REPLACEMENTS ARE COMPLETE AND THE PIPELINE WAS RETURNED TO SERVICE ON 8/12/2020. A SUPPLEMENTAL REPORT WAS FILED ON 8/19/2020 PER THE REQUEST OF BRIAN PIERZINA (PHMSA) - WHO REQUESTED THAT ITEM A4 BE UPDATED TO THE TIME THAT THE FEATURE WAS FIRST DISCOVERED, RATHER THAN THE TIME WHEN IT WAS DETERMINED THROUGH EVALUATION AND COST ESTIMATES THAT THIS QUALIFIED AS A DOT REPORTABLE INCIDENT. THE THROUGH WALL FEATURE WAS UNCOVERED 7/15/20 AT 16:00 MT. WE DETERMINED THE NEXT DAY THAT REPLACEMENT COSTS WOULD EXCEED $50K AND THAT THIS COULD NOT BE INCLUDED WITH A REVISION OF A FORMER INCIDENT REPORT RELATED TO THE SAME PIGGING PROJECT FOR THE LINE IN QUESTION. THE COST DETERMINATION WAS MADE 7/16/2020 AT 12:48 MT, AND A NOTIFICATION TO THE NRC WAS MADE ON THE SAME DATE AT 15:13 MT.