ENTERPRISE PRODUCTS OPERATING LLC — Gas transmission and gathering — incident on 2011-12-11

Gas transmission and gathering incident in FALLS CITY, KARNES County, TX. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 21566 NATURAL GAS released, $120,000 reported property damage. Operator-reported incident data submitted to PHMSA, generally within 30 days. Records may be supplemented or corrected and do not represent final agency causal findings.

Report number: 20120006.

Operator ID: 31618.

Reported incident date: 12/11/2011 20:55.

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: ON DECEMBER 11, 2011 AN ENTERPRISE PRODUCTS PIPELINE, BURNELL TO ADKINS LINE 9122, OVERPRESSURED AND HAD A FAILURE. THE OVERPRESSURIZATION WAS CAUSED TO BOTH MONITOR AND REGULATOR STATION VALVES FAILING TO FUCTION PROPERLY AT THE SAME TIME. THE PIPELINES ESTABLISHED MAOP IS 612 PSIG. DUE TO THE FAILURE OF THE PIPELINE REGULATORS THE PIPELINE WAS PRESSURED UP TO 847PSIG BEFORE FAILING. ONE CITY, PANNA MARIA, TX, LOST GAS SUPPLY FOR APPROXIMATELY 2 DAYS. THE TOTAL NUMBER OF RESIDENTS WITHOUT GAS DURING THIS TIME PERIOD WAS ABOUT TEN HOUSEHOLDS. THE PIPELINE WAS OUT OF SERVICE FOR TWENTY DAYS. IT WAS STARTED BACK UP ON DECEMBER 31, 2011. SUPPLEMENTAL/FINAL REPORT 8-7-12 THE FAILURE INVESTIGATION IDENTIFIED DEBRIS LODGED IN THE PRESSURE SENSING TUBES ON BOTH REGULATORS. THE INVESTIGATION ALL INDICATED THAT THERE WAS NOT A HIGH PRESSURE ALARM IN PLACE TO NOTIFY OF THE INCREASE IN PRESSURE. TO ADDRESS THESE ITEMS, REDUNDANT PRESSURE SENSING CONTROLS WERE INSTALLED AT THIS SITE AND A HIGH PRESSURE ALARM WAS ADDED TO THE CONTROL LOGIC.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EQUIPMENT FAILURE — MALFUNCTION OF CONTROL/RELIEF EQUIPMENT.

PHMSA indexed costs: $221,264 reported total cost, $132,930.541 in 1984 dollars, $252,630.91 in current-year dollars.

PHMSA trend flags, standardized causes, and indexed costs are analytical fields added to operator-reported incident data. They do not represent final agency causal findings.