NUSTAR PIPELINE OPERATING PARTNERSHIP L.P.

Incident Narrative

"AT APPROXIMATELY 12:15PM ON 30JAN25 WHILE SUNOCO LOCAL OPERATIONS PERSONNEL WERE MAKING THEIR ROUNDS, IT WAS DISCOVERED AT THE MP90 - PIG TRAP SITE THAT A RELIEF VALVE WAS LEAKING. THE SPILL WAS CONFIRMED AT 12:15PM. THE RELIEF VALVE WAS ISOLATED IMMEDIATELY, AND NOTIFICATIONS WERE MADE TO SUNOCO MANAGEMENT IN THE WICHITA OFFICE AT 12:43PM. ADDITIONAL LOCAL SUNOCO PERSONNEL WERE MOBILIZED TO THE SITE TO BEGIN CLEANUP OPERATIONS. SORBENT PADS, TRASH PUMPS, AND DRUMS WERE USED FOR INITIAL COLLECTION OF FREE PRODUCT ON TOP OF THE GROUND. THE SUNOCO MAINTENANCE CREW WAS NOTIFIED AND MOBILIZED TO THE SITE ON THE MORNING OF 31JAN25 WITH A VAC TRUCK AND EXCAVATOR TO CONTINUE CLEANUP OPERATIONS. AT THE TIME OF THE INCIDENT, IT WAS OVERCAST AND 46 DEGREES F. THE GROUND WAS FROZEN AND THERE WAS MINIMAL WIND. AN INITIAL ESTIMATE OF 75 GALLONS OF GASOLINE WAS RELEASED. A FAILED RELIEF VALVE WAS IDENTIFIED AS THE CAUSE OF RELEASE. PIG TRAP SITE IS RURAL, AND THE RELEASE IMPACTED SOIL AROUND THE SITE. THERE WAS NO IMPACT TO WATER, WILDLIFE, OR PUBLIC. NOTIFICATIONS MADE TO STATE AND FEDERAL AGENCIES (NRC, SOUTH DAKOTA DANR, PHMSA, ONE-CALL). SOUTH DAKOTA DANR ARRIVED ON SITE AT APPROXIMATELY 5:00PM, TO ACCESS DAMAGES AND CLEAN-UP ACTIVITIES. NO ADDITIONAL CONCERNS IDENTIFIED. SUNOCO CONTACTED PINNACLE ENGINEERING TO LEAD THE CLEAN-UP / REMEDIATION EFFORTS. THE PINNACLE CONSULTANT ARRIVED ON SITE AT APPROXIMATELY 8:20AM ON THE MORNING OF 31JAN25. INITIAL CLEAN-UP AND REMEDIATION EFFORTS ARE COMPLETE. CONTINUED REMEDIATION WILL BE DETERMINED BASED ON FURTHER ASSESSMENT TO BE COMPLETED BY 11MAR25. THE SUNOCO ENGINEERING TEAM IS REVIEWING NEW DESIGN OPTIONS TO REPLACE THE FAILED RELIEF VALVE."