PUBLIC SERVICE CO OF NORTH CAROLINA — Gas transmission and gathering — incident on 2014-01-10

Gas transmission and gathering incident in CANDLER (NEAR ASHEVILLE), BUNCOMBE County, NC. Reported cause: EXCAVATION DAMAGE. Reported consequences: 0 fatalities, 0 injuries, 2786 NATURAL GAS released, $235,193 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: 20140018.

Operator ID: 15938.

Reported incident date: 1/10/2014 15:51.

Location detail: T-33 MP-9.90

Cause detail: PREVIOUS DAMAGE DUE TO EXCAVATION ACTIVITY

Cause detail: MISCELLANEOUS ROOT CAUSES

Cause detail: PREVIOUS DAMAGE

Cause detail: PSNC ENERGY SAND HILL T-33 PIPELINE RUPTURE JANUARY 10, 2014 THE FOLLOWING INFORMATION UPDATES THE NARRATIVE PROVIDED IN THE ORIGINAL INCIDENT AND INCLUDED ATTACHMENTS. CAUSE OF RUPTURE PSNC ENERGY DETERMINED FROM THE INVESTIGATION OF THE REMOVED SECTION OF T-33 AND OBSERVATIONS MADE DURING THE EMERGENCY RESPONSE / RESTORATION EFFORTS THAT THE RUPTURE WAS CAUSED BY MECHANICAL DAMAGES THAT OCCURRED DURING THE 2003 INSTALLATION OF THE 4-INCH PLASTIC DISTRIBUTION. THE DISTRIBUTION PIPE WAS INSTALLED BY PSNC ENERGY'S CONTRACTOR USING A HORIZONTAL DIRECTIONAL BORE METHOD. AT THE TIME OF THE 2003 CONSTRUCTION, SAND HILL ROAD HAD NOT BEEN WIDENED TO THE POINT WHERE IT EXTENDED OVER T-33. THE LOCATION OF T-33 WAS NOT PROPERLY IDENTIFIED AND THE BORE PATH FOR THE DISTRIBUTION LINE WAS ESSENTIALLY THE SAME AS T-33. WHILE FOLLOWING THE T-33 DITCH LINE THE BORING HEAD CREATED SHALLOW SCRATCHES ALONG T-33. THE DIRECTIONAL BORING HEAD HIT THE 18-INCH CULVERT AND CREATED DEEP GOUGES AS THE HEAD WAS ROTATED TO CLEAR THE OBSTRUCTION. THE DEEP GOUGES CREATED SHEAR CRACKS WHICH SET UP CONDITIONS THAT ULTIMATELY LED TO THE RUPTURE OF THE PIPELINE. THIS WAS CONFIRMED BY METALLURGICAL TECHNOLOGIES, INC. P.A. REPORT 2014141 (3/20/2014). THIS REPORT DISCOUNTED ANY ADDITIONAL STRESSES CREATED BY THE CULVERT. REMEDIAL ACTIONS PRESSURE ON T-33 WAS LIMITED TO 175 PSIG FROM THE TIME OF THE TEMPORARY REPAIR UNTIL PERMANENT REPAIRS COULD BE MADE. PSNC ENERGY FILED A SAFETY RELATED CONDITION REPORT IN ACCORDANCE WITH 49 CFR PART 191.25 ON JANUARY 15, 2014. PSNC ENERGY MADE THE DECISION TO REPLACE THE 1,000 FOOT SECTION OF T-33 THAT RAN PARALLEL TO THE 4-INCH DISTRIBUTION LINE. ONSITE CONSTRUCTION BEGAN ON JANUARY 16, 2014 AND THE NEW SEGMENT WAS IN SERVICE ON FEBRUARY 1, 2014 WHICH CORRECTED THE PIPELINE ISSUES WHICH CREATED THE SAFETY RELATED CONDITION REPORT. SYSTEM PRESSURE HAS BEEN RESTORED TO 350 PSIG AND THE SCADA ALARMS HAVE BEEN RESET. AN UPDATE OF THE STATUS OF THE SAFETY RELATED CONDITION REPORT WAS PROVIDED TO CHRIS TAYLOR, PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION - SOUTHERN REGION, BY EMAIL FROM SCOTT SWINDLER ON MARCH 3, 2014. DAMAGE ESTIMATES THE FIRE AND RUPTURE CAUSED DAMAGE TO SEVERAL CARS, HOMES AND COMMERCIAL BUILDINGS IN THE AREA. IN ADDITION, THE ROAD, AND SEVERAL OTHER UTILITIES WERE DAMAGED. ALL DAMAGE ESTIMATES WITHIN THE INCIDENT REPORT HAVE BEEN UPDATED WITH ACTUAL VALUES AS OF FEBRUARY 13, 2015.

PHMSA trend classification: significant incident, not serious.

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

PHMSA indexed costs: $777,287 reported total cost, $396,570.092 in 1984 dollars, $966,618.55 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.