ROCKIES EXPRESS PIPELINE LLC

Incident Narrative

"ORIGINAL SUBMITTED: 10/10/2025 ON 9/13/2025 AT 10:00PM CHANDLERSVILLE STATION UNIT 5100 PLC RACK POWER SUPPLY FAILED. ON 9/14/2025 AT 10:30AM A NEIGHBOR OF THE STATION CALLED A TALLGRASS TECHNICIAN AND REPORTED A LOUD NOISE. THE TECHNICIAN ARRIVED ONSITE AT 10:50AM AND CLOSED THE SUCTION AND DISCHARGE VALVES MANUALLY STOPPING THE LEAK. INCIDENT INVESTIGATION IS ONGOING (SUPPLEMENTAL WILL BE FILED). SUPPLEMENTAL SUBMITTED: 12/16/2025 UPDATED PART E, QUESTION 11 UPDATED PART G APPARENT CAUSE TO G6 EQUIPMENT FAILURE UPDATED NARRATIVE: INVESTIGATION IS COMPLETE AND TALLGRASS HAS UPDATED RELEVANT SECTIONS OF REPORT. UNIT 5100 PLC POWER SUPPLY FAILED CAUSING THE PROCESSORS TO GO OFFLINE. THE ""U1 PLC COMM FAILURE"" ALARM DID NOT LATCH AND MOVED FROM ALARM SUMMARY TO THE ALARM HISTORY ONLY DURING THE TIME THE TECHNICIAN WAS ESTABLISHING A REMOTE CONNECTION. THE TECHNICIAN ON-CALL COULD NOT DETERMINE THAT THE HMI ON UNIT 5100 WAS NO LONGER DISPLAYING ACCURATE DATA AND DECIDED NOT TO REPORT TO THE STATION TO INVESTIGATE THE TYPE 6 ALARM. THE UNIT SUCTION AND DISCHARGE VALVES PERFORMED AS DESIGNED WHICH IS TO FAIL LAST STATE. THE BLOWDOWN VALVE PERFORMED AS DESIGNED AND FAILED TO THE OPEN POSITION. TALLGRASS HAS COMPLETED THE FOLLOWING CORRECTIVE ACTIONS: 1. ""TYPE 6"" CALLOUTS WILL GO TO OCC AS WELL AS THE TG PERSON ON-CALL FOR THE FACILITY. 2. OPERATIONS MANAGERS WILL COMMUNICATE TO TEAMS THAT A ""TYPE 6"" CALLOUT REQUIRES THEM TO REPORT TO SITE TO INVESTIGATE. TALLGRASS IS WORKING ON THE FOLLOWING CORRECTIVE ACTIONS: 3. EVALUATE IF A FIELD DESIGN CHANGE TO THE REX UNIT SUCTION AND DISCHARGE VALVES FAIL SAFE IS APPROPRIATE. 4. EVALUATE THE CALLOUT TYPES USED AT CHANDLERSVILLE AND DETERMINE IF WE CAN IMPROVE CLARITY BY MAKING THEM MORE DESCRIPTIVE."