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Loose Nut Likely Caused Explosion at Harlem Sewage Plant

By Jeff Mays | November 2, 2011 4:37pm
Another view of the fire that closed Riverbank State Park.
Another view of the fire that closed Riverbank State Park.
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Kevin Boursiquot/Twitter

HARLEM — A loose nut that connected a fuel line to a fuel pump was the likely cause of the July 20 fire at the North River Sewage Treatment Plant that sent upward of 260 million gallons of untreated sewage into the Hudson River, according to a report commissioned by the Department of Environmental Protection.

Once the nut loosened, a spray of fuel oil hit the engine's extremely hot turbochargers and likely ignited the initial fire, the report said. However, because of the extensive damage caused by the fire, the exact cause may never be known, DEP Commissioner Carter Strickland said in a statement.

"While the initial cause could not be determined with absolute certainty, the report includes a number of steps that DEP can take in the future to minimize the risk from failures of such small pieces of hardware at North River and at similar DEP facilities throughout the city," Strickland said.

The FDNY also issued several recommendations, including increasing response planning at the agency, conducting quarterly drills and making sure key documents are maintained outside of its  sewage plants in lock boxes.

The fire and explosion shut down all five engines of the plant and caused the evacuation of Riverbank State Park which is built on top of the sewage plant. The Hudson River and Harlem River were closed to recreational users and four beaches in Staten Island and Brooklyn were also closed.

The report by engineering and consulting firm Black & Veatch ruled out deficient maintenance or improper operation as a cause for the nut that may have sparked the fire.

However, just as something as simple as a nut may have caused the fire, other basic issues helped to feed it. Because fuel continued to feed the fire for five minutes after the engine was shut down, Black & Veatch recommended a remote fuel stop be installed in the control room. A shield to prevent fuel from contacting the turbocharger was also recommended.

The fire and release of sewage sparked new attention to the issue of sewage overflow into the city's waterways. Each year, 30 billion gallons of rain runoff and untreated sewage are sent into the city's waters every time it rains because of the way the century-old sewer system is designed. The North River plant sends 800 million gallons into the Hudson each year.

DEP has committed to implement better procedures to notify the public of when sewage is in the waterways but has yet to announce specifics.

State Sen. Adriano Espaillat is authoring legislation that would require more public notification when untreated sewage enters the city's waterways.

"It's far more important to have strong notification systems in place that alert the public in cases of these accidents. In the coming days, my office will be unveiling legislation that does just that," he said.

Tracy Brown, a spokeswoman for Riverkeeper, a watchdog group that monitors the Hudson and its estuaries, said she too was disappointed to not read more about the sewage discharge and DEP's plans for better public notification.

"The one thing we expected to see in the report that we didn't see was DEP addressing the sewage that was discharged. The public is very interested in the sewage release that happened as a result of the fire," she said.