NORTHERN NATURAL GAS CO — Gas transmission and gathering — incident on 2004-03-25

Gas transmission and gathering incident in WOODWARD, IA. Reported cause: 9. Reported consequences: 0 fatalities, 0 injuries, $235,000 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: 20040035.

Operator ID: 13750.

Reported incident date: 3/25/2004.

Cause detail: THIRD PARTY EXCAVATION DAMAGE

Cause detail: AT APPROXIMATELY 9:00 A.M. ON MARCH 25, 2004, THE NORTHERN NATURAL GAS COMPANY (NORTHERN) 16-INCH DES MOINES "B" BRANCH LINE RUPTURED APPROXIMATELY 1 3/4 MILES SOUTHEAST OF WOODWARD, IA. THE FIRE AND EXPLOSION WERE REPORTED TO NORTHERN'S OPERATIONS COMMUNICATION CENTER BY A PASSERBY. NO EMPLOYEES OR THIRD PARTIES WERE PRESENT AT THE TIME OF THE RUPTURE AND THERE WERE NO INJURIES. NORTHERN DISCOVERED THAT A TILING CONTRACTOR, KUEHI BROTHERS, L.L.C. (KUEHI), INSTALLED TILING OVER THE GAS PIPELINE IN DECEMBER 2003. THERE WAS NO ONE-CALL PLACED FOR THIS EXCAVATION. NORTHERN TRANSPORTED SAMPLES OF THE DAMAGED PIPE TO BRYAN LABORATORIES, INC., IN HOUSTON, TEXAS FOR ANALYSIS. THE REPORT FROM BRYAN LAB STATES THAT THE RUPTURING OF THE PIPE WAS THE RESULT OF THE WEAKENING AFFECTS OF RECENT GOUGING AND DENTING OF THE EXTERNAL SURFACE. THE APPEARANCE AND THE SEVERITY OF THE DAMAGE ARE CONSISTENT WITH THAT RESULTING FROM EXCAVATING OR FARMING OPERATIONS. BRYAN LABS FOUND NO DEFECTS IN MATERIAL OF MANUFACTURING.

PHMSA trend classification: significant incident, not serious.

PHMSA standardized cause: EXCAVATION DAMAGE — THIRD PARTY EXCAVATION DAMAGE.

PHMSA indexed costs: $235,000 reported total cost, $144,372.075 in 1984 dollars, $307,867.862 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.