CONSUMERS ENERGY CO — Gas transmission and gathering — incident on 2013-12-21

Gas transmission and gathering incident in HAMILTON, ALLEGAN County, MI. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 6648 NATURAL GAS released, $500 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: 20140009.

Operator ID: 2748.

Reported incident date: 12/21/2013 22:33.

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: AT APPROXIMATELY 10:33 PM ON DECEMBER 21, 2013, BLOWDOWN VALVE 614 AT OVERISEL COMPRESSOR STATION TRAVELED OPEN AND VENTED GAS TO ATMOSPHERE THROUGH THE STATION EMERGENCY SHUT-DOWN VENT FOR APPROXIMATELY 57 MINUTES. IN TOTAL, ABOUT 6.65 MMCF WAS VENTED TO ATMOSPHERE. PER MANUFACTURER'S RECOMMENDATION, CONSUMERS ENERGY IS PURSUING PLANS TO INSTALL WEATHER-TIGHT ENCLOSURES AND/OR NEW PILOT ASSEMBLIES FOR ALL BIFFI-STYLE VALVES IDENTIFIED AT ITS COMPRESSOR STATIONS. WHERE IMPLEMENTED, THE ENCLOSURES WILL HOUSE THE PILOT VALVE AS WELL AS THE CONTROLLER. AS A NEAR-TERM MEASURE, VALVES ARE BEING MONITORED REGULARLY FOR ICE BUILD-UP TO PREVENT RE-OCCURRENCE. ADDITIONALLY, VENT REPLACEMENT IS IN PROGRESS FOR ALL IDENTIFIED BIFFI VALVES AND IS SCHEDULED FOR COMPLETION BY JANUARY 31, 2014. IN THE EVENT OF A LEAKING SHAFT SEAL, UNRESTRICTED VENTS WILL HELP PREVENT PRESSURE BUILD-UP AT THE VALVE ACTUATOR, THUS PREVENTING THE BLOWDOWN VALVE FROM IMPROPER OPERATION.

PHMSA trend classification: not significant, not serious.

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

PHMSA indexed costs: $32,395 reported total cost, $26,002.219 in 1984 dollars, $32,405.803 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.