The City's Sewer System

About 70% of New York City's vast, century-old sewer system is made up of combined sewers, carrying both household waste and storm runoff through gravity-fed sewer mains into wastewater treatment plants.

A major downside of the combined sewer system is that any rainfall over a tenth of an inch per hour causes overflows -- oil, garbage, antifreeze, dog poop, you name it -- blasting out of the sewers into the city's waterways.

Environmentalists have criticized the city for its "casual" attitude about raw sewage overflows into its waterways, with the city's archaic combined sewer system often named as the primary problem.

New York is one of only about 800 US cities that still use a combined sewer system. In 20,000 other US cities, wastewater and storm runoff are carried in separate pipes, a more efficient system that prevents overflows by keeping storm runoff out of wastewater treatment plants.

Rather than separate sewers from storm drains, the city, as part of a 10-year, multi-billion dollar upgrade to bring its sewage treatment plants into compliance with the federal Clean Water Act, has built huge underground reservoirs to hold the overflows until the waste can be safely pumped into a treatment plant.

Most of the city's waste treatment plants were built after World War II.  The Red Hook plant in Brooklyn, one of the last to be built, didn't open until the late 1980s.

As recently as 1986, all of the sewage from the Upper West Side of Manhattan was dumped untreated into the Hudson River. The Hudson's rebirth was made possible by wastewater treatment.

The city's ancient sewer system is a constant and critical infrastructure issue. Although the city's Department of Environmental Protection supposedly monitors the system via remote-controlled video cameras run through the pipes to spot leaks and cracks and patch or replace damaged pipes before they break, that clearly doesn't always happen.

And when sewer mains break, as they have on 92nd Street and 79th Street in Bay Ridge over the past month, the city responds only on a case-by-case basis -- instead of addressing the problem on a system-wide basis.

The post from Gotham Gazette.

More from Environmental Health Perspectives.

More from Brooklyn Paper.