CONSUMERS ENERGY CO — Gas transmission and gathering — incident on 2019-01-21

Gas transmission and gathering incident in MANCHESTER, WASHTENAW County, MI. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 32564 NATURAL GAS released, $1,405 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: 20190018.

Operator ID: 2748.

Reported incident date: 1/21/2019 2:43.

Location detail: PLANT II

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: ON JANUARY 21, 2019 AT APPROXIMATELY 02:43 HOURS, AN OPERATOR --ALREADY ONSITE RESPONDING TO A LOW PILOT PRESSURE ALARM AT CONSUMERS ENERGY'S FREEDOM COMPRESSOR STATION --OBSERVED GAS BLOWING AT OR NEAR THE PLANT II FIREGATE BLOW DOWN VALVES. DURING HIS INVESTIGATION THE OPERATOR DETERMINE THAT THREE (3) OF THE PLANT 2 FIREGATE BLOW DOWN VALVES WERE IN THE OPEN POSITION. THE OPERATOR WAS SUCCESSFUL AT CLOSING TWO OF THE THREE BLOW DOWN VALVES BUT UNABLE TO CLOSE THE THIRD VALVE (VALVE 614). THE OPERATOR PERFORMED A MANUAL EMERGENCY SHUT DOWN (ESD) OF PLANT 2 BY OPENING A PILOT GAS VENT VALVE TO STOP THE GAS FROM BLOWING. THE PLANT 2 ESD ISOLATION VALVE (VALVE 609) STUCK OPEN AND GAS CONTINUED TO ESCAPE. THE OPERATOR ATTEMPTED TO HAND PUMP VALVE 609 TO THE CLOSE POSITION WITH NO SUCCESS. THE OPERATOR WITH THE ASSISTANCE OF 2 STATION MECHANICS CLOSED VALVES 267 AND 268, WHICH ARE DOWNSTREAM OF VALVE 609. THIS OPERATION SUCCESSFULLY STOPPED THE GAS FROM BLOWING. AN INCIDENT INVESTIGATION IDENTIFIED A CATALYTIC HEATER FAILURE PREVENTED THE PILOT GAS REGULATOR FROM OPERATING RAPIDLY ENOUGH TO MAINTAIN PRESSURE FOR THE PILOT GAS SYSTEM CAUSING THE BLOW DOWN VALVES TO OPEN AND GAS TO BLOW. OPERATIONS PERSONNEL ARE EVALUATING ACTIONS TO IMPLEMENT THAT WILL MINIMIZE FUTURE OCCURRENCE.

PHMSA trend classification: significant incident, not serious.

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

PHMSA indexed costs: $103,237 reported total cost, $105,545.23 in 1984 dollars, $131,105.943 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.