These boats are made for human-waste trafficking.
On Nov. 25 the city christened three new sludge boats, the vessels used to transport the refined sewage of wastewater treatment facilities, including the onion-domed plant on Newtown Creek in Greenpoint. The sludge that gives the watercraft their name is one of two byproducts of the sewage treatment process, the other being water. The new boats, costing $106 million altogether, are necessary because New York’s toilets are always flushing.
“The sludge never stops,” said Gordon Arnold, captain of the Port Richmond, one of the new boats.
To get a picture of what the sludge boats do in relation to sewage plants, imagine a drinking glass placed under a pitcher that is always pouring liquid, Arnold said.
“When that glass is full, you better have another glass there in a hurry,” he said.
When a boat is late, the city has a “sludge emergency,” Arnold added, though he declined to elaborate.
The Port Richmond and her fellow fleet members the Rockaway, and the Hunt’s Point, come custom-designed to navigate the shallow waters of Newtown Creek and the low clearance of the Pulaski Bridge. The city is decommissioning two older boats and keeping another, so the fleet will soon total four. Each of the new vessels takes six people to operate and can carry as many as a million gallons of muck.
Unlike their predecessors, the new boats can load sludge directly from the Newtown Creek Wastewater Treatment Plant, nearly a mile upstream at the end of Humboldt Street. The old boats stopped at the mouth of the fetid inlet to drain an 800,000-gallon storage tank on shore, connected by pipeline to the plant. Now the tank, at the foot of Dupont Street, has been dismantled to make way for the Greenpoint Landing mega-development and an expansion of Newtown Barge Park.
The Department of Environmental Protection estimates that its boats transport 1.2 billion gallons of sludge each year. Of the city’s 14 wastewater treatment plants, eight are equipped to separate the liquid in the sludge from the solid, a process known as dewatering. The other six plants must ship their goop to those eight. Newtown Creek’s plant is the biggest in the city, with sewage coming in from more than a million people in Williamsburg, Bushwick, Bedford-Stuyvesant, Greenpoint, and lower Manhattan. It does not dewater, so its sludge gets shipped to Wards Island.
At Wards Island the goop goes into a centrifuge, where it is spun until the separation occurs. The solid, a black-dirt-like substance called “cake,” is handed off to a private contractor for disposal, in landfills and in abandoned mines in Pennsylvania. The nitrogen-rich liquid, or centrate, is eventually released as clean water.
The city used to dump the sludge in the ocean, 12 miles offshore, according to Arnold, until Congress banned the practice in 1988. For many years afterwards, the city turned the dried-up dung into fertilizer, but it recently decided the effort was too expensive.
Today, getting rid of the cake costs the city $73 to $77 per ton.
The new boats were partly covered by a federal stimulus grant, but the cost of wastewater treatment is passed on to consumers by way of their water bill.
According to the department’s deputy commissioner for design and construction, the new boats are going into service just in time.
“We’re getting ready for the busiest day of the year,” Vincent Sapienza said, “Black Friday.”