WAYNE, Mich. -

Consumers Energy has released a fact-finding report about last year's deadly explosion at the William C. Franks Furniture Store in Wayne.

The blast leveled the furniture store, killing employees James Zell and Leslie Machniak on December 29, 2010.

The report was filed Dec. 20, 2011 with the Michigan Public Service Commission. The company also will file a report with a federal agency, the Pipeline and Hazardous Materials Safety Administration.  

The 65-page report identified three possible causes for the incident, but said the exact cause couldn’t be determined because of a number of factors.

The three possible causes:

Broken gas line theory.  After the incident, investigators found a two-inch steel gas main that was broken at a coupling and leaking natural gas.  The fracture point was in an alley about 230 feet from the building involved in the incident. Testing found the fracture occurred suddenly from an undetermined downward force on the top of the pipe. It couldn’t be determined from the available evidence if the pipe separation occurred before the incident or as a result of the incident.

Broken gas line-sewer theory. A second possible cause that can’t be determined with certainty is that the pipe fracture occurred before the incident and natural gas migrated into the building through a sanitary sewer.

Interior leak theory. The third possible cause is that there was a gas leak inside the building.  As the first responders handled the incident, the interior gas piping was removed from the building with power equipment.  During that process, the piping was damaged and investigators couldn’t piece it together afterward and reconstruct the system to determine if there was a leak.