PHMSA Report 20160032 - NORTHERN NATURAL GAS CO — Gas transmission and gathering — incident on 2016-03-14 | Regulus

Gas transmission and gathering incident in Not Within a Municipality, WRIGHT County, MN. Reported cause: EXCAVATION DAMAGE. Reported consequences: 0 fatalities, 0 injuries, 7376 NATURAL GAS released, $20,000 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: 20160032.

Operator ID: 13750.

Reported incident date: 3/14/2016 16:50.

Location detail: MILEPOST 10.2

Cause detail: PREVIOUS DAMAGE DUE TO EXCAVATION ACTIVITY

Cause detail: MISCELLANEOUS ROOT CAUSES

Cause detail: PREVIOUS DAMAGE

Cause detail: ON MARCH 14, 2016 AT ABOUT 17:00 HOURS LOCAL RESIDENTS AND EMERGENCY RESPONDERS NOTIFIED THE OPERATIONS COMMUNICATION CENTER OF A VISIBLE AND AUDIBLE LEAK IN THE MIDDLE OF A FARM FIELD ABOUT 1.5 MILES SOUTH OF HOWARD LAKE, MINNESOTA. THE LEAK WAS CAUSED BY A CRACK IN THE 3-INCH BRANCH LINE. THE BRANCH LINE CONTAINED OBVIOUS THIRD PARTY DAMAGE. WE BELIEVE THE LANDOWNER WAS DEEP TILLING IN THE LATE 1960'S OR 70'S WHEN HE STRUCK AND BENT THE BRANCH LINE. AFTER NEARLY 50 YEARS, THE DAMAGE FINALLY REACHED CRITICAL FLAW SIZE AND A 1/16-INCH WIDE BY 2-INCH LONG CRACK OPENED. GAS PRESSURE IN THE PIPELINE DROPPED TO AS LOW AS 611 PSI WHERE IT REMAINED. NORTHERN LET THE LEAK CONTINUE UNTIL THE SECTION COULD BE ISOLATED AND BYPASSED USING LINE STOPPING EQUIPMENT. THE SECTION OF PIPE WAS REPLACED AND THE LINE RETURNED TO SERVICE ON MARCH 18, 2016 WITHOUT ANY INTERRUPTION OF SERVICE TO CUSTOMERS. A SECTION OF THE DAMAGED SECTION WAS SENT TO A METALLURGICAL LABORATORY FOR ANALYSIS BUT IT IS HIGHLY UNLIKELY THEY WILL BE ABLE TO DETERMINE WHEN THE DAMAGE OCCURRED.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EXCAVATION DAMAGE — PREVIOUS DAMAGE DUE TO EXCAVATION.

PHMSA indexed costs: $300,000 reported total cost, $217,320.71 in 1984 dollars, $377,426.877 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.