COLONIAL PIPELINE CO

Incident Narrative

AT APPROXIMATELY 17:15 ON JANUARY 8 2019, AN OPERATOR AT COLLINS TANK FARM NOTICED STAINED GRAVEL AND PRODUCT SHEEN WITHIN THE DIKE OF TANK 2075. SUBSEQUENT INVESTIGATION REVEALED PRODUCT ACCUMULATING AT THE BASE OF THE TANK. APPROPRIATE NOTIFICATIONS WERE MADE AND PRODUCT CONTAINMENT AND RECOVERY ACTIVITIES WERE INITIATED. THE TANK WAS EMPTIED AND PREPARED FOR INTERNAL INSPECTION. INITIAL INTERNAL VISUAL INSPECTION REVEALED A POSSIBLE CRACK IN THE TANK FLOOR NEAR THE SUMP WELL. NDT INSPECTION OF THE ENTIRE TANK FLOOR HAS BEEN COMPLETED PENDING FINAL REPORT. ALL CONTAMINATED SOIL HAS BEEN REMOVED FROM THE TANK DIKE AND REPLACED WITH CLEAN FILL. MDEQ HAS BEEN ON SITE AND RECEIVED UPDATES ON SOIL REMOVAL ACTIVITY. A FINAL OR SUPPLEMENTAL SPILL REPORT WILL BE FILED WITH PHMSA UPON DISCOVERY OF ANY NEW FINDINGS. FINAL REPORT UPDATE - THE RELEASE IS ESTIMATED TO HAVE STARTED ON 6 JANUARY 2019, BASED ON TANK VOLUME AND RELEASE CALCULATIONS. THE RELEASE WAS DISCOVERED AT 17:10, ON 8 JANUARY 2019. THE DECISION TO NOTIFY THE NRC WAS MADE AT 18:55 LOCAL TIME ON 8 JANUARY 2019 WHEN IT WAS DETERMINED THAT RESPONSE AND REPAIR EFFORT WOULD EXCEED $50,000. INCIDENT ANALYSIS (IA) WAS COMPLETED ON 20 MARCH 2019. THE ANALYSIS DETERMINED THE TANK FLOOR DEVELOPED A CRACK IN A SUMP DIFFUSER LEG SUPPORT PLATE. THE ROOT CAUSE OF THE FAILURE COULD NOT BE POSITIVELY IDENTIFIED. HOWEVER, THE IA DID IDENTIFY TWO POSSIBLE CONTRIBUTING FACTORS. TO THE DEVELOPMENT OF THE CRACK AS FOLLOWS: MATERIAL OR EQUIPMENT FAILURE: AN INSPECTION DISCOVERED THE SUMP DIFFUSER PLATE HAD DETACHED FROM THE TANK INTERIOR WALL DURING AN INTERNAL INSPECTION PERFORMED ON 22 AUGUST 2018. THAN 2075 PROJECT RECORDS REVEAL THAT A NITROGEN PUSH CONDUCTED IN 2016 USED TANK 20175 AS THE NITROGEN BLOWDOWN POINT FOR A PIPE REPAIR PERFORM ON A NEARBY RIGHT OF WAY. IT IS POSSIBLE THAT NITROGEN, VENTING THROUGH THE TANK, COULD HAVE MOVED THE DIFFUSER SUPPORT LEGS IN SUCH A MANNER AS TO CAUSE DAMAGE TO THE WELDED SUPPORT PLATE. MOVEMENT OF THE SUMP DIFFUSER LEG RESTING ON THE SUPPORT PLATE MAY ALSO HAVE CAUSED THE FLOOR TO FLEX ENOUGH TO AFFECT SOIL COMPACTION AROUND THE SUMP, CONTRIBUTING TO CRACK DEVELOPMENT. LOSS OF SOIL COMPACTION: A VOID BETWEEN THE TANK FLOOR AND SOIL AROUND THE SUMP BOX WAS OBSERVED DURING TANK FLOOR REPAIRS. THIS VOID MAY HAVE OCCURRED DURING FLOOR REPLACEMENT CONSTRUCTION IN 2007. LOSS OF SOIL COMPACTION OVER TIME COULD HAVE CAUSED THE WELD PLATE TO CRACK FROM METAL FATIGUE DURING TANK CYCLING. THE TANK WAS REPAIRED AND RESTORED TO SERVICE. ADDITIONALLY, THE VOLUME AND INCIDENT COST HAVE WERE UPDATED TO THE CORRECT VOLUME OF RELEASE AND COST OF REPAIRS. THIS CONCLUDES PHMSA REPORTING FOR THIS INCIDENT.