The failure of a nut connecting a fuel injector to a fuel pump at Manhattan’s North River Wastewater Treatment Plant is one of the most likely initial causes of the four-alarm fire that shuttered the plant for days last July, according to a Dept. of Environmental Protection report released yesterday. However, the initial cause of the blaze, which caused millions of gallons of raw sewage to spill from the plant into the Hudson River, cannot be determined with absolute certainty because the fire damaged or destroyed much of the equipment involved, DEP says.
The nut may have failed because it was over or under tightened, causing a microscopic tear during routine maintenance at the plant, the agency says. Fuel oil may have escaped from the tear and hit an extremely hot engine turbocharger, sparking the fire.
Another possible initial cause of the blaze could be that a leak from a flexible fuel line located near the turbocharger caused a similar chain of events, the agency says.
The report is available at DEP’s Web site.
“From the beginning it was clear that the original source of the fire was near one of the main sewage pump engines,” DEP says. The report includes steps that the agency may take to minimize risk “from failures of such small pieces of hardware” at plants, it says.
The agency says it has already taken steps to improve safety at the Harlem-based plant, including relocating larger fuel pipes away from hot surfaces like turbochargers, installing kill switches in the control room to immediately cut fuel in case of fire, and installing more flexible connectors to minimize damage to pipes associated with vibrations. DEP says it will continue to evaluate other proposals detailed in the report.
The city hired Black & Veatch, an engineering, consulting and construction firm with experience in forensic reviews of industrial incidents, to investigate the fire. Black & Veatch retained T.J. Russo Consultants, a fire investigation and analysis firm.