DENBURY GULF COAST PIPELINES, LLC

Incident Narrative

ON 10/7/2020 AT 17:31, DENBURY BEGAN BLOWDOWN ACTIVITIES TO PERFORM WORK REQUIRED TO RECONNECT A DOWNSTREAM PIPELINE SEGMENT TO AN UPSTREAM SECTION OF PIPE ON THE DELHI PIPELINE SYSTEM AT THE SATARTIA MLV SEVERAL MILES SOUTHWEST OF SATARTIA, MISSISSIPPI AND ADJACENT TO STATE HIGHWAY 3. THE SECTION WAS ORIGINALLY REMOVED AND TEMPORARILY CAPPED, IN ORDER TO POSITIVELY ISOLATE THE DELTA PIPELINE INCIDENT LOCATION (FEBRUARY 2020) FROM THE DOWNSTREAM, PRESSURIZED SEGMENT OF PIPE. BECAUSE THE SATARTIA MLV DID NOT SEAL PROPERLY, THERE WAS MORE PRODUCT IN THE SEGMENT, BETWEEN THE SATARTIA MLV AND THE TEMPORARY WELD CAP, THAN ANTICIPATED. ONCE IT WAS DETERMINED THAT THE MLV WAS NOT SEALING, THE DENBURY OPERATOR BEGAN TO CLOSE THE BLOW-DOWN VALVE, IN ORDER TO SHUT-DOWN THE OPERATION FOR THE EVENING. AS THE OPERATOR ATTEMPTED TO CLOSE THE VALVE, AFTER SEVERAL ATTEMPTS, HE FOUND THAT THE HANDWHEEL ON THE GEAR OPERATOR WOULD NOT TURN. BECAUSE OF THE JOULE-THOMSON EFFECT, ASSOCIATED WITH THE MLV PRODUCT BLOW-BY, IT IS BELIEVED THAT THE OPEN 8' BLOWDOWN VALVE (THAT WAS IN THE FLOW PATH OF THE LEAKING MLV) FROZE IN THE OPEN POSITION DUE TO INTERNAL ICE FORMATION. DUE TO THE POTENTIAL OF PUBLIC IMPACT, THE YAZOO COUNTY EMA WAS NOTIFIED AT 20:26 AND MSDEQ EMERGENCY SERVICES WAS NOTIFIED AT 20:34. THE NATIONAL RESPONSE CENTER (NRC) WAS THEN NOTIFIED AT 21:21 (NRC #1289255). DUE TO THE PROXIMITY OF THE RELEASE TO HIGHWAY 3, THE HIGHWAY WAS SHUT DOWN TO AVOID THE POSSIBILITY OF A VEHICLE ACCIDENT DUE TO LOW VISIBILITY CAUSED BY THE CO2 CLOUD. AS AN ADDITIONAL PRECAUTION, EMERGENCY RESPONSE CONTRACTORS WERE DISPATCHED TO CONDUCT AIR-MONITORING IN THE SURROUNDING AREA, TO ENSURE THE SAFETY OF THE RESPONSE PERSONNEL AND LOCAL PUBLIC. ATMOSPHERIC TESTING IN AND AROUND THE RELEASE SITE WAS CONTINUOUSLY CONDUCTED THROUGHOUT THE NIGHT. ALL AREAS BEING MONITORED MAINTAINED ADEQUATE OXYGEN LEVELS THROUGHOUT THE DURATION OF THE RELEASE. ON 10/8/2020 AT 18:00, ONCE THE PIPELINE SEGMENT PRESSURE HAD BEEN REDUCED ENOUGH TO PREVENT ADDITIONAL CO2 BLOWBY THROUGH THE MLV, THE BLOWDOWN VALVE THAWED ENOUGH TO ALLOW IT TO BE CLOSED. ONCE THE BLOWDOWN VALVE WAS CLOSED, THE PRODUCT RELEASE WAS STOPPED, AND HIGHWAY 3 WAS RE-OPENED. ON 10/9/2020 AT 15:43, THE NRC WAS CONTACTED TO SUBMIT AN UPDATE (NRC #1289386) TO THE ORIGINAL NRC REPORT. ON 10/12/2020, ALL VALVES AT THE SATARTIA MLV LOCATION WERE FLUSHED AND LUBRICATED AND DETERMINED TO BE IN WORKING ORDER. ONCE THE TEMPORARY WELD CAPS WERE REMOVED AND REPLACED WITH TESTED PIPE, THE PIPELINE WAS RESTARTED ON 10/26/2020 AT 12:30 WITH NO ISSUES.