MICHIGAN CONSOLIDATED GAS CO (MICHCON) — Gas distribution — incident on 2008-02-26

Gas distribution incident in GRAND RAPIDS, KENT County, MI. Reported cause: 25. Reported consequences: 0 fatalities, 1 injuries, $1,035,900 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: 20080057.

Operator ID: 12408.

Reported incident date: 2/26/2008.

Cause detail: UNKNOWN

Cause detail: AT 14:56 ON FEBRUARY 26, 2008, MICHCON RECEIVED A REPORT OF A GAS LEAK INSIDE A TWO-STORY COMMERCIAL BUILDING AT 1500-1502 WEALTHY STREET SE, ON THE SOUTHEAST CORNER OF WEALTHY AND ETHEL AVENUE. THE CALLER REPORTED A STRONG ODOR OF GAS, PARTICULARLY IN THE BASEMENT OF THE BUILDING. A MICHCON TECHNICIAN WAS DISPATCHED TO THE ADDRESS AT 14:59, AND ARRIVED AT 15:21. A SECOND GAS LEAK REPORT WAS RECEIVED AT 15:04 FOR THE SAME BUILDING; THIS CALLER ALSO REPORTED A STRONG GAS ODOR IN THE BASEMENT BUT ALSO AN ODOR OF GAS IN HIS BUSINESS ON THE SECOND FLOOR. UPON ARRIVAL, THE MICHCON TECHNICIAN ENTERED THE FIRST FLOOR OF THE BUILDING AND BEGAN CHECKING FOR THE PRESENCE OF COMBUSTIBLE GAS. FINDING NO COMBUSTIBLE GAS READINGS ON THE FIRST FLOOR, THE TECHNICIAN CHECKED AROUND THE DOORWAY LEADING TO THE BASEMENT OF THE BUILDING TO CONTINUE HIS INVESTIGATION IN THE BASEMENT WHERE THE ODOR INTENSITY HAD BEEN REPORTED AS BEING STRONGEST. THE BASEMENT DOOR AT THE TOP OF THE FIRST FLOOR STAIRWELL WAS CLOSED, AND THE TECHNICIAN CHECKED FOR THE PRESENCE OF COMBUSTIBLE GAS AROUND THE FRAME AND AT THE BASE OF THE CLOSED DOOR. FINDING NO INDICATIONS OF COMBUSTIBLE GAS, THE TECHNICIAN OPENED THE DOOR AND IMMEDIATELY HIS GAS DETECTOR REGISTERED A READING OF 4% GAS CONCENTRATION AND RISING. WHILE TURNING TO EXIT THE BUILDING, THE TECHNICIAN WAS STRUCK BY A RUSH OF HEATED GASES AND DEBRIS. AN EXPLOSION LEVELED THE TWO-STORY STRUCTURE, DAMAGING NEARBY BUILDINGS AND STREWING DEBRIS ACROSS THE INTERSECTION OF WEALTHY AND ETHEL. A REPORT WAS RECEIVED FROM THE GRAND RAPIDS FIRE DEPARTMENT AT 15:40 ADVISING MICHCON THAT AN EXPLOSION HAD OCCURRED ON WEALTHY STREET, BUT THAT THEY HAD NO ADDRESS. MICHCON CREWS BEGAN ARRIVING ON THE SCENE AT 15:48. COMBUSTIBLE GAS READINGS WERE FOUND IN SEVERAL ADJACENT BUILDINGS AND IN SOME OF THE SEWER LINES IN WEALTHY STREET EAST AND WEST OF ETHEL. HIGHEST CONCENTRATIONS OF COMBUSTIBLE GAS WERE FOUND NEAR THE PARKING AREA ALONG THE EAST SIDE OF THE BUILDING AND ALONG THE WALLS OF THE BUILDINGS ON THE NORTH SIDE OF WEALTHY STREET, ACROSS FROM 1500-1502 WEALTHY. MICHCON FOUND A CIRCUMFERENTIAL BREAK WITH APPROXIMATELY 1/4-INCH OF SEPARATION BETWEEN THE PIPE ENDS ON A 6� CAST IRON MAIN IN WEALTHY STREET, WHICH WAS SUCCESSFULLY REPAIRED AT 21:14 USING A BOLT-ON STAINLESS STEEL CLAMP. AT 23:30, MICHCON SHUT DOWN THE MAINS IN THE INTERSECTION AS A PRECAUTIONARY MEASURE. THE 1-INCH COPPER SERVICE LINE TO 1500-1502 WEALTHY WAS DISCONNECTED FROM THE MAIN AT 23:36, BUT DUE TO CONTINUING FIREFIGHTING ACTIVITIES AND THE SUBSTANTIAL DEBRIS MICHCON WAS UNABLE TO LEAK TEST OR RECOVER THE REMNANTS OF THE SERVICE LINE AT THAT TIME. MICHCON GAVE TELEPHONIC NOTICE TO THE MICHIGAN PUBLIC SERVICE COMMISSION IN LANSING AT 16:31 AND TO THE NATIONAL RESPONSE CENTER AT 16:44. FIVE PEOPLE, INCLUDING FOUR BUILDING OCCUPANTS AND MICHCON�S TECHNICIAN, WERE TRANSPORTED TO LOCAL HOSPITALS. MICHCON�S SERVICE TECHNICIAN WAS ADMITTED AND THE REST WERE RELEASED LATER THAT DAY. MICHCON PERFORMED A SUCCESSFUL LEAK TEST OF THE SERVICE LINE AT NORMAL 2 PSIG OPERATING PRESSURE ON MARCH 20, 2008, INCLUDING APPROXIMATELY 20 FEET OF 1-INCH COPPER PIPE BETWEEN THE MAIN AND THE BUILDING, 2 FEET OF 1-INCH COATED STEEL PIPE WHICH SERVED AS THE BUILDING ENTRANCE, AND A 1-INCH COUPLING OUTSIDE THE BUILDING WALL CONNECTING THE TWO PIPING MATERIALS. NO LEAKAGE WAS FOUND ON THE SERVICE LINE. THE CAUSE OF THE EXPLOSION AND THE SOURCE OF THE GAS HAVE NEVER BEEN DETERMINED. ON MARCH 20, 2008, A SEGMENT OF THE BROKEN 6-INCH CAST IRON MAIN FOUND ON FEBRUARY 26, 2008, INCLUDING THE CIRCUMFERENTIAL FRACTURE SEALED BY THE STAINLESS STEEL CLAMP, WAS CUT AND REMOVED FROM WEALTHY STREET. LABORATORY EXAMINATION OF THE 6-INCH PIPE REMOVED FROM THE MAIN IN FRONT OF 1500-1502 WEALTHY STREET SE REVEALED IT TO BE GREY CAST IRON WITH A COMPLETE CIRCUMFERENTIAL CRACK, THE RESULT OF A SINGLE OVERLOAD EVENT. THE FRACTURE FACES EXHIBITED GRAPHITIC CORROSION AT SEVERAL LOCATIONS UP TO DEPTHS OF 70 TO 80 PERCENT OF THE PIPE WALL THICKNESS. THE REMAINING WALL THICKNESS WAS SUFFICIENT TO MAINTAIN THE INTEGRITY OF THE PIPE UNDER NORMAL OPERATING CONDITIONS. THE CONDITION OF THE FRACTURE FACES RULED OUT THE POSSIBILITY THAT THE BREAK OCCURRED WEEKS OR MONTHS PRIOR TO THE EXPLOSION AT 1500-1502 WEALTHY, BUT METALLURGICAL TESTING WAS UNABLE TO ESTABLISH WHETHER THE BREAK RESULTED FROM THE FORCE OF THE EXPLOSION OR IF IT OCCURRED JUST PRIOR TO THE EXPLOSION. BOTH POSSIBILITIES WERE DETERMINED TO BE EQUALLY LIKELY. MICHCON AND SEVERAL OTHER INVESTIGATORY ENTITIES, INCLUDING FIRE OFFICIALS, INSURANCE ADJUSTERS, AND FAILURE ANALYSTS, WERE UNABLE TO EVALUATE THE POSSIBILITY THAT NATURAL GAS HAD LEAKED FROM FUEL PIPING INSIDE THE BUILDING AT 1500-1502 WEALTHY. DEBRIS FROM THE EXPLOSION WAS PUSHED FROM THE SURROUNDING STREETS AND ALLEYS BACK INTO THE BASEMENT WITHIN HOURS OF THE EXPLOSION, DAMAGING OR DESTROYING THE BUILDING FUEL PIPING IN THE PROCESS. NONE OF THIS PIPING COULD BE EXAMINED TO DETERMINE IF IT COULD HAVE BEEN A POSSIBLE SOURCE OF A GAS LEAK INTO THE BASEMENT OF THE BUILDING, NOR COULD AN IGNITION SOURCE BE DETERMINED. HOWEVER, ANALYSIS DID CONFIRM THAT A RELATIVELY MINOR LEAK FROM THE CUSTOMER FUEL PIPING INSIDE THE BUILDING COULD HAVE PRODUCED AN EXPLOSIVE ENVIRONMENT IN THE BASEMENT WITHIN HOURS. MICHCON WAS NOT ABLE TO DETERMINE WHETHER THE FRACTURE OF THE 6-INCH CAST IRON PIPE OCCURRED PRIOR TO OR AS A RESULT OF THE EXPLOSION AT 1500-1502 WEALTHY STREET SE ON FEBRUARY 26, 2008. THEREFORE, MICHCON CANNOT DETERMINE WHETHER THE EXPLOSION WAS CAUSED BY NATURAL GAS LEAKING FROM THE CAST IRON MAIN OR, AS HAS BEEN SUGGESTED BY SOME FIRE AND EXPLOSION INVESTIGATORS, THE EXPLOSION RESULTED FROM THE IGNITION OF NATURAL GAS LEAKING FROM A CUSTOMER�S FUEL LINE INSIDE THE BUILDING. BOTH POTENTIAL CAUSES WERE DEEMED POSSIBLE; NEITHER COULD BE ELIMINATED. THE CAUSE OF THIS INCIDENT HAS BEEN CLASSIFIED AS �UNKNOWN.�

PHMSA trend classification: significant incident, serious incident, not fire-first.

PHMSA standardized cause: ALL OTHER CAUSES — UNKNOWN.

PHMSA indexed costs: $1,035,900 reported total cost, $577,546.872 in 1984 dollars, $1,422,320.197 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.