QUESTAR PIPELINE COMPANY — Gas transmission and gathering — incident on 2011-11-18

Gas transmission and gathering incident in NEAR GREEN RIVER, SWEETWATER County, WY. Reported cause: EQUIPMENT FAILURE. Reported consequences: 0 fatalities, 0 injuries, 0 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: 20110395.

Operator ID: 12874.

Reported incident date: 11/18/2011 17:00.

Location detail: MP 95.97

Cause detail: MALFUNCTION OF CONTROL/RELIEF EQUIPMENT

Cause detail: SUPPLEMENTAL BEING FILED TO CLARIFY THE INCIDENT CAUSE. REGULATOR FROZE-OFF AND CAUSED THE STATION PRESSURE TO RISE TO THE RELIEF VALVE SET-POINT, THUS ACTIVATING THE RELIEF VALVE AS INTENDED. THE RELIEF VALVE OPERATED AS DESIGNED AND RELIEVED TO PREVENT OVER-PRESSURIZATION ON THE DOWNSTREAM PIPING.

PHMSA trend classification: not significant, not serious.

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

PHMSA indexed costs: $25,300 reported total cost, $17,700.871 in 1984 dollars, $21,932.675 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.