NUSTAR PIPELINE OPERATING PARTNERSHIP L.P.

Incident Narrative

AT 6:20 AM ON 1/28/2023, A HUNTER REPORTED AN AMMONIA ODOR NEAR THE OLD LOCATION OF VALVE 2-7. THE VALVE HAD BEEN REMOVED MANY YEARS AGO, BUT SEVERAL BURIED STOPPLE TEE FITTINGS WERE IN THE IMMEDIATE AREA. THE INITIAL REPORTED LOCATION WAS INACCURATE. ADDITIONAL INVESTIGATION DETERMINED THE EXACT LOCATION. A NUSTAR EMPLOYEE ARRIVED AT THE LOCATION AT 8:04 AM AND VERIFIED SOME SILT MOVING IN THE WATER ABOVE THE UPSTREAM STOPPLE TEE OF THE OLD VALVE 2-7. THE PIPELINE WAS SHUT DOWN AT 8:56 AM. VALVE 2-6 WAS CLOSED TO ISOLATE THE RELEASE AREA AT 9:44 AM. AFTER LOWERING PRESSURE FROM THE LEAK SITE, VALVE 2-8 WAS CLOSED AT 10:44 AM. THE INITIAL INDICATION WAS THAT THE LEAK WAS REASONABLY LOW ENERGY, LIKELY NOT EXCEEDING THE REPORTABLE QUANTITY OF 100 LBS / 24-HOUR PERIOD. HOWEVER, IN AN ABUNDANCE OF CAUTION, NOTIFICATION CALLS WERE MADE TO AGENCIES BEGINNING AT 9:12 AM. ADDITIONAL SUPPORT PERSONNEL AND REPAIR CREWS MOBILIZED TO THE SITE ON 1/29/2023, AND REPAIR PLANS WERE DEVELOPED. DEWATERING OF THE AREA WAS STARTED ON 1/31/2023, AND EXCAVATION OF THE STOPPLE BEGAN ON 2/1/2023. THE CAUSE OF THE LEAK WAS TWO SEGMENT PLUGS, BOTH RELEASING ONLY AMMONIA VAPOR. THE STOPPLE TEE SEGMENT PLUGS WERE WELDED CLOSED ON 2/1/2023 AT 4:00 PM, WHICH COMPLETELY STOPPED THE AMMONIA LEAK. THE STOPPLE WAS CUT OUT AND REPLACED WITH PRE-TESTED PIPE. THE LINE WAS RETURNED TO SERVICE ON 2/3/23 AT 4:33 PM. THE RELEASE VOLUME WAS CALCULATED TO BE 1.91 BARRELS.