DENBURY ONSHORE, LLC

Incident Narrative

ON 9/9/2020 AT 19:19, THE DENBURY CONTROL CENTER (DCC) WAS NOTIFIED BY A PRIVATE CITIZEN OF A WHITE CLOUD NEAR THE LOCKHART JUNCTION VALVE LOCATION OFF CANE MARKET RD (IN THE AREA OF THE CONNECTION TO THE NEJD PIPELINE). THE DCC CONTACTED THE PIPELINE FOREMAN WHO DISPATCHED THE APPROPRIATE DENBURY PERSONNEL TO THE SITE. DENBURY PERSONNEL ARRIVED ONSITE AT 21:50 AND MADE THE DETERMINATION THAT A CARBON DIOXIDE (CO2) LEAK WAS OCCURRING NEAR THE JUNCTION OF THE LOCKHART LATERAL AND NEJD PIPELINE. IT WAS INITIALLY UNKNOWN WHETHER THE LEAK WAS ON THE LOCKHART LATERAL OR THE NEJD PIPELINE. THE LA STATE POLICE HAZARDOUS MATERIAL HOTLINE WAS NOTIFIED AT 22:45 (STATE POLICE REPORT # 20-03507), FOLLOWED BY THE NOTIFICATION TO THE LIVINGSTON PARISH OFFICE OF EMERGENCY PREPAREDNESS AT 23:01. THE NATIONAL RESPONSE CENTER (NRC) WAS THEN NOTIFIED AT 23:07 (NRC #1286945). AT 22:21 THE NEJD PIPELINE PUMPS SUPPLYING PRESSURE TO THE AFFECTED AREA WERE SHUT DOWN. BECAUSE THE AREA OF THE LEAK COULD NOT BE ACCESSED DUE TO LACK OF VISIBILITY CAUSED BY THE CO2 RELEASE, THE INTERCONNECT VALVE COULD NOT BE SAFELY SHUT, IN ORDER TO ISOLATE THE NEJD PIPELINE FROM THE LOCKHART LATERAL. THEREFORE THE NEJD MAINLINE VALVES THAT ISOLATE THE NEJD SEGMENT, CONTAINING THE LOCKHART INTERCONNECT, WERE CLOSED IN ORDER TO ULTIMATELY LIMIT THE LEAK VOLUME, IN THE EVENT THE LEAK WAS DETERMINED TO BE ON THE NEJD PIPELINE. THE NEJD MAINLINE VALVES WERE CLOSED AT 23:02 AND 23:23. AT 23:48 HOURS, EMERGENCY RESPONSE CONTRACTORS ARRIVED ON-SITE AND BEGAN CONDUCTING PRELIMINARY AIR-MONITORING FOR RESPONSE PERSONNEL. IN ADDITION, AIR MONITORING AND ATMOSPHERIC TESTING IN AND AROUND THE FAILURE SITE WAS CONDUCTED AND CONTINUED THROUGHOUT THE NIGHT. AT 7:15 ON 9/10/2020, SITE CONDITIONS SIGNIFICANTLY IMPROVED SO THAT DENBURY PERSONNEL WERE ABLE TO SAFELY ACCESS THE LOCKHART JUNCTION VALVE LOCATION. AT THIS TIME THE LOCATION OF THE LEAK WAS IDENTIFIED TO BE ON THE LOCKHART LATERAL, SO THE TAP VALVE AND A DOWNSTREAM, ABOVE GROUND, ISOLATION VALVE WERE IMMEDIATELY CLOSED AT THE FACILITY TO ISOLATE THE LEAK. AT 8:05 NO PRODUCT WAS OBSERVED COMING FROM THE LEAK LOCATION. IT WAS DETERMINED THAT THE LEAK OCCURRED DUE TO AN ISOLATION GASKET FAILURE AT AN ABOVE GROUND FLANGED JOINT ON THE LOCKHART LATERAL . ON 9/11/2020 THE FAILED ISOLATION GASKET WAS REMOVED AND REPLACED. REPAIRS WERE COMPLETED AT 10:00 AND THE PIPELINE SEGMENT WAS RETURNED TO SERVICE. ON 9/11/2020 AT 16:42, THE NRC WAS CONTACTED TO SUBMIT AN UPDATE (NRC #1287129) TO THE ORIGINAL NRC REPORT. THE ISOLATION GASKET WAS SENT TO AN INDEPENDENT LAB FOR FAILURE ANALYSIS. ON JANUARY 21, 2021 DENBURY RECEIVED THE RESULTS OF THE ANALYSIS, WHICH INDICATED THAT THE GASKET SHOWED SIGNS OF DAMAGE (BLISTERING, TEARS, CRACKS AND SPALLING) THAT WAS CONCENTRATED AT THE BOTTOM, ON BOTH THE UPSTREAM AND DOWNSTREAM SIDES. THE REPORT INDICATES THAT THE FAILURE INITIATED AT THE BOTTOM AND BECAUSE OF THE ADDITIONAL SIGNS OF DAMAGE, SUGGESTS THAT THE PIPELINE FLANGE ALIGNMENT MAY HAVE CHANGED OVER THE PERIOD THAT THE FLANGE HAD BEEN INSTALLED AND MAY HAVE LED TO THE FAILURE.