OSHA Lab, Water Agency Probe Chicago Plant Explosion | Columbus Ohio Dump Trucks
The roof of a sludge concentration building was brought down by a methane explosion.
IMAGE: WFLD-TV VIA AP
The dust has settled from a methane explosion last month that brought down the roof of a sludge concentration building at the Calumet water reclamation plant on Chicago’s far south side, but there is still uncertainty as to what triggered the blast.
The roof collapse injured 10 workers, one seriously. Carl Malinowski, 51, had worked in maintenance at the 96-year-old plant for more than a decade when he was called on Aug. 30 to perform the routine procedure of removing a frozen bolt with an acetylene torch.
His bosses at the Metropolitan Water Reclamation District of Greater Chicago describe Malinowksi as a “skilled, trained ironworker.” On the day of the explosion, he was carrying a portable gas meter meant to detect high levels of dangerous gases in the air.
Hours later, 70 rescue workers had to dig and tunnel through 40 feet of concrete to save the trapped and badly injured Malinowski. An initial Chicago Fire Dept. investigation found that a methane explosion caused by a worker’s torch was the cause.
“Methane is explosive and must be handled properly,” said Allison Fore, public affairs officer at the MWRD. “There are levels of methane that are a natural by-product of our process, and methane is automatically assumed to be present. We test the atmosphere for multiple gasses, including methane, hydrogen sulfide, oxygen and carbon monoxide.”
Methane only becomes explosive in higher concentrations. The National Institute for Occupational Safety and Health’s maximum recommended safe methane concentration for workers during an eight-hour period is 0.1%. Methane levels between 5% and 15% are required for an explosion. The Occupational Safety and Health Administration and the Illinois Dept. of Labor each are conducting their own investigations. Fore said the MWRD will retain a forensic investigator to determine the cause and the agency will release a report upon its conclusion.
“Our finding from a strictly technical view is ignition of a significant amount of methane that was in an area where a torch was being used,” said Lawrence Langford, director of media affairs and communications at the Chicago Fire Dept. “Others will determine questions as to how the situation occurred. It should not be assumed the operator of the torch is responsible.”
Langford said the OSHA, Labor and MWRD investigations will try to answer questions such as: Did the air monitors function? Did the air-handling system operate correctly? Was the supervisor correct to order use of a torch? Was the atmosphere below the bolt monitored and known?
Fore said the Calumet plant can operate at capacity without the gravity belt thickener system of the sludge concentration building destroyed in the blast. Fore said the impacted portion of the building was rehabilitated in the last decade. Over the coming weeks, MWRD will conduct training sessions at all of its plants on the dangers of hazardous atmospheres.