VECTREN ENERGY DELIVERY OF OHIO

Incident Narrative

ON SATURDAY, NOVEMBER 11, 2011, AT 2:06 PM, VECTREN ENERGY DELIVERY OF OHIO WAS NOTIFIED BY THE CITY OF FAIRBORN FIRE DEPARTMENT OF A HOUSE EXPLOSION AT 367/369 WAYNE DRIVE IN FAIRBORN. VECTREN PERSONNEL WERE DISPATCHED TO THE SCENE AND SUBSEQUENTLY CLOSED THE VALVE TO THE SERVICE LINE PROVIDING NATURAL GAS TO THE STRUCTURE. AN INITIAL REPORT FROM THE FAIRBORN FIRE DEPARTMENT INDICATED THE STRUCTURE INVOLVED IN THE INCIDENT WAS 'TOTALLY DESTROYED AND REDUCED TO A FLAMING PILE OF RUBBLE'. IT FURTHER DESCRIBED THE DAMAGE TO ADJACENT STRUCTURES INCLUDING BLOWN OUT WINDOWS, A COLLAPSED EXTERIOR WALL AND SMALL AMOUNTS OF FIRE TO THE ROOF LINES. THE INITIAL REPORT ALSO COMMENTED THAT ALTHOUGH THE CAUSE REMAINS UNDER INVESTIGATION, THE PRELIMINARY THOUGHT IS THAT 'EXCAVATION WORK AROUND A NATURAL GAS LINE CAUSED THE LINE TO FRACTURE ON THE INSIDE OF THE BASEMENT WALL'' 'ALLOWING THE FREE FLOW OF GAS TO FILL THE INTERIOR OF THE STRUCTURE AND A UNDETERMINED IGNITION SOURCE SPARKED THE EXPLOSION.' VECTREN IS CONTINUING ITS OWN INDEPENDENT INVESTIGATION INTO THE ORIGIN OF THIS INCIDENT. SUPPLEMENTAL REPORT NARRATIVE, JANUARY 10, 2012: THE NATURAL GAS SERVICE LINE FOR THE DUPLEX AT 367-369 WAYNE DRIVE RAN UNDERGROUND FROM THE CURB BOX THROUGH THE CONCRETE BASEMENT WALL INTO THE BASEMENT OF 367 WAYNE DRIVE. AFTER GOING STRAIGHT THROUGH THE BASEMENT WALL, THE NATURAL GAS SERVICE LINE THEN WENT TO THE LEFT AT A TEE CONNECTION TO THE METER FOR 367 WAYNE DRIVE AND THEN TO THE RIGHT AT AN NINETY DEGREE ELBOW THROUGH THE BLOCK WALL, DIVIDING THE BASEMENTS, TO THE METER FOR 369 WAYNE DRIVE. VECTREN GENERALLY CONCLUDES THAT THE BACKHOE OPERATOR, DIGGING A TRENCH OUTSIDE THE BASEMENT FOUNDATION BETWEEN THE SIDEWALK AND THE DUPLEX, DAMAGED THE NATURAL GAS SERVICE LINE. THIS DAMAGE CAUSED THE NATURAL GAS SERVICE LINE TO BEND AND PULL AND TO PLACE A LARGE AMOUNT OF TENSION ON THE GAS SERVICE LINE AND THE THREADS THAT SCREWED INTO THE NINETY DEGREE ELBOW INSIDE THE BASEMENT OF 367 WAYNE DRIVE. THIS LARGE AMOUNT OF TENSION CAUSED THE THREADS OF THE GAS SERVICE LINE, WHICH WERE SCREWED INTO THE NINETY DEGREE ELBOW, TO FRACTURE AT THIS THREAD JOINT RELEASING NATURAL GAS INTO THE BASEMENT OF 367 WAYNE DRIVE. THE NATURAL GAS EXPLODED FROM AN UNDETERMINED IGNITION SOURCE ONCE THE NATURAL GAS AND AIR MIXTURE HAD REACHED A POINT BETWEEN THE LOWER EXPLOSIVE LIMIT AND THE UPPER EXPLOSIVE LIMIT. THE FORCE OF THE EXPLOSION DID NOT CAUSE THE FRACTURE TO THIS THREAD JOINT. VECTREN'S INVESTIGATION ALSO DETERMINED THAT THE PROPER AMOUNT OF MERCAPTAN OR ODORANT WAS IN THE NATURAL GAS AT THE TIME AND THAT THERE WERE NO OTHER NATURAL GAS LEAKS. THE SERVICE LINE WAS IN GOOD CONDITION AND LEAK TIGHT. VECTREN'S INVESTIGATION ALSO DETERMINED THAT THERE WERE NO REQUESTS TO LOCATE THE NATURAL GAS SERVICE LINE BEFORE THESE UNFORTUNATE EVENTS AND THAT THERE WAS NO REQUEST TO TURN OFF THE NATURAL GAS. ALTHOUGH VECTREN DOES NOT RELY ON THE INITIAL REPORT OF THE FAIRBORN FIRE DEPARTMENT OR THE INCIDENT REPORT AND SUPPLEMENTAL REPORT OF THE STATE FIRE MARSHAL, VECTREN'S CONCLUSIONS ARE CONSISTENT WITH THE FACTS CONTAINED IN THESE REPORTS.