ALASKA PIPELINE CO — Gas transmission and gathering — incident on 2012-09-05

Gas transmission and gathering incident in ANCHORAGE, AK. Reported cause: NATURAL FORCE DAMAGE. Reported consequences: 0 fatalities, 0 injuries, 7950 NATURAL GAS released, $0 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: 20120104.

Operator ID: 207.

Reported incident date: 9/5/2012 17:45.

Location detail: A505

Cause detail: HIGH WINDS

Cause detail: INCIDENT: RELEASE OF GAS AT APC EAST ANCHORAGE GATE SITE DUE TO OVER PRESSURE ON 460 PSI SYSTEM DATE: SEPTEMBER 5, 2012 VOLUME RELEASED: 7.95 MILLION CUBIC FEET CHRONOLOGY OF EVENTS : WEATHER CONDITIONS: EXTREMELY HIGH WIND CONDITIONS IN EXCESS OF 120 MPH CAUSED NUMEROUS POWER OUTAGES AND SHUT DOWN OF POWER GENERATION STATIONS THROUGHOUT THE COOK INLET. TIMES ARE ESTIMATED +/- 2 MINUTES. 17:42 LOST POWER TO EAST ANCHORAGE GATE STATION ( EAG ) 17:42 SIGNIFICANT LOSS OF LOAD TO MLP POWER PLANT NUMBER 2 DUE TO FAULT CONDITIONS ON POWER SYSTEM 17:45 RELIEF OPENED ON 460 PSI SYSTEM AT EAST ANCHORAGE GATE DUE TO OVERPRESSURE 17:47 RELEASE OF GAS REPORT CALLED INTO ENSTAR (APC) DISPATCH 17:59 TECHNICIANS DISPATCHED TO EAG TO INVESTIGATE CAUSE 18:47 TECHNICIAN ON SITE AND CONTROLLED INCIDENT MITIGATING CIRCUMSTANCES APC'S EAG STATION INCLUDES A GAS DELIVERY SALES POINT TO MUNICIPAL LIGHT AND POWER'S STATION NUMBER 2. HIGH WINDS IN THE ANCHORAGE BOWL ON THE EVENING OF SEPTEMBER 5 CAUSED NUMEROUS POWER SYSTEM FAULTS TO OCCUR. THE POWER SYSTEM FED BY MLP 2 WAS INTERRUPTED DUE TO THE FAULT CONDITIONS, INTERRUPTING BOTH GENERATION AND ALSO POWER DELIVERY TO THE APC EAG STATION. BACK UP BATTERIES AT EAG WERE NOT CAPABLE OF CONTINUED SCADA SURVEILLANCE. ON IMMEDIATE CURTAILMENT OF GAS TO MLP 2, REGULATOR MALFUNCTION CAUSED THE 460 PSI SYSTEM TO OVERPRESSURE FOLLOWED BY OPENING OF THE OVERPRESSURE RELIEF. RESPONSE TIME WAS GREATER THAN WOULD NORMALLY BE EXPECTED DUE TO TRAFFIC CONDITIONS AGAIN CAUSED AGAIN TO LOSS OF POWER GENERATION.

PHMSA trend classification: not significant, not serious.

PHMSA standardized cause: NATURAL FORCE DAMAGE — HIGH WINDS.

PHMSA indexed costs: $48,500 reported total cost, $40,347.917 in 1984 dollars, $49,866.309 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.