ONEOK NGL PIPELINE, LLC

Incident Narrative

AT APPROXIMATELY 11:16 AM ON APRIL 8, 2020 A LANDOWNER CONTACTED LOCAL ONEOK FIELD PERSONNEL REGARDING A POSSIBLE LEAK AT THE MP 52 VALVE SETTING ON THE ONEOK #1-10-INCH PIPELINE. FIELD PERSONNEL IMMEDIATELY NOTIFIED SUPERVISORY PERSONNEL AND RESPONDED TO THE LOCATION ARRIVING AT APPROXIMATELY 11:37 AM. UPON ARRIVAL AN ICE BALL APPROXIMATELY 4 INCHES IN DIAMETER WAS DISCOVERED ON THE GROUND AT THE LOCATION OF MP 52 VALVE. THE UPSTREAM MAINLINE VALVE (MP 53) WAS CLOSED AT 12:02 HRS. AND PUMPS DOWNSTREAM AT THE ONEOK EASTLAND PUMP STATION WERE USED TO REDUCE PRESSURE ON THE PIPELINE UNTIL 13:11 HRS. WHEN THE DOWNSTREAM VALVE (MP 45) WAS CLOSED TO ISOLATE THE SEGMENT OF PIPE CONTAINING THE LEAK. THE ISOLATED 8-MILE SECTION OF PIPELINE WAS PURGED OF HYDROCARBONS WITH NITROGEN AND THE LEAK SITE EXCAVATED. UPON EXCAVATION ONEOK DETERMINED THE SPIRAL WOUND GASKET BETWEEN THE UNDERGROUND CHECK VALVE AND MAINLINE VALVE HAD FAILED INTERNALLY, RESULTING IN THE RELEASE OF HYDROCARBONS. THE CHECK VALVE AND A SECTION OF PIPE WERE REMOVED AND REPLACED AND THE PIPELINE RETURNED TO SERVICE AT APPROXIMATELY 20:50 HRS. ON APRIL 10, 2020. ONEOK DETERMINED APPROXIMATELY 62 GALLONS OF HYDROCARBONS WERE RELEASED TO THE SOIL. ALL CONTAMINATED SOILS HAVE BEEN REMEDIATED. UPDATE: 5/11/2020 ROOT CAUSE INVESTIGATION, ONEOK USES THE CAUSE MAP PROCESS FOR CAUSE INVESTIGATION. FINAL: 5/20/2020 UPDATE: FINAL 8/19/2020 GPS COORDINATES UPDATED PER PHMSA REQUEST.