MICHIGAN CONSOLIDATED GAS CO (MICHCON)

Incident Narrative

A TREE BRANCH BROKEN DURING A WINDY RAIN STORM FELL ONTO A POLE-MOUNTED ELECTRICITY DISTRIBUTION CONDUCTOR, WHICH FELL TO THE GROUND AND CONTINUED TO ARC AND SPARK FOR A LENGTHY PERIOD OF TIME. INVESTIGATION REVEALED THE COPPER LOCATING WIRE INSTALLED ADJACENT TO THE 2-INCH PLASTIC GAS MAIN BECAME ENERGIZED, GENERATING INTENSE LOCALIZED HEAT WHICH MELTED THE PLASTIC. NATURAL GAS AT APPROX 52 PSIG WAS RELEASED AND WAS IGNITED BY AN UNKNOWN SOURCE, ALTHOUGH IT HAS BEEN SPECULATED THAT THE ARCING ELECTRIC CONDUCTOR WAS THE SOURCE. A MICHCON CREW RESPONDED BY PINCHING THE 2-INCH PLASTIC PIPE UPSTREAM OF THE RUPTURE, STOPPING THE LEAK AND INTERRUPTING SERVICE TO 38 CUSTOMERS. THE LEAKING MAIN WAS REPAIRED USING A 60-INCH LENGTH OF PRE-TESTED POLYETHYLENE PLASTIC. AN AIR TEST AT 54 PSIG WAS APPLIED TO THE MAIN AND SERVICE LINES DOWNSTREAM OF THE PINCH, BUT THE TEST DID NOT HOLD AND THE DEAD-END SYSTEM TO THE SOUTH OF THE PINCH REMAINED OUT OF SERVICE. A LEAK SURVEY OF THE GAS DISTRIBUTION SYSTEM UPSTREAM OF THE PINCH FOUND LEAKS AT ANOTHER 20 LOCATIONS, SOME NEARLY 2 MILES FROM THE ORIGINAL MAIN LEAK AT 866 SCENIC DRIVE. ARC BURNS AND PERFORATIONS OF POLYETHYLENE PLASTIC SERVICE LINE TUBING WERE FOUND ALONG SCENIC DRIVE, ON WEST GILES ROAD AS FAR EAST AS 4175 W GILES, AND NORTH OF W GILES AT 1680 BENJAMIN ROAD IN LAKETON TOWNSHIP. ALL 20 LEAKS WERE ELIMINATED BY REPLACEMENT OF VARIOUS LENGTHS OF NEW SERVICE LINE TUBING. THE EVENT WAS REPORTED TO THE NATIONAL RESPONSE CENTER AT 18:59 ON OCTOBER 18, 2012, WHEN MICHCON REALIZED THE COST OF REPAIRS ALREADY MADE AND OTHER LEAKS THAT MAY HAVE REMAINED TO BE FOUND AND REPAIRED WOULD LIKELY EXCEED THE THRESHOLD FOR REPORTING AS AN INCIDENT. ON FRIDAY, OCTOBER 19, 2012, MICHCON RE-ESTABLISHED GAS SERVICE TO THE MAINS AND SERVICE LINES SOUTH (DOWNSTREAM) OF THE PINCH ALONG SCENIC DRIVE AND FENNER ROAD. THE MAINS AND SERVICE LINES WERE SURVEYED FOR LEAKS; EIGHT MORE LEAKS WERE FOUND AND REPAIRED. THE EVENT WAS DECLARED FINISHED AT 22:45 ON OCTOBER 19, 2012.