The Treatment - The Ripple Effect: The Fate of Freshwater in the Twenty-First Century - page 41

past Wall Street, and bends east under the river to encompass North Brooklyn. The
drainage includes 1.33 million people spread over twenty-five square miles. Because it
collects water from such a wide area, a mere one-eighth of an inch of rain translates into
63 million gallons of excess water flowing into the system, while an inch of precipitation
results in 504 million extra gallons of storm water.
“That's a lot of water,” said Jim Pynn, the plant's lean and garrulous superintendent.
“A slow, steady rain is easier for the system to absorb than an intense storm. It only
needs to be rainin' hard for twenty or thirty minutes before we have to use the
throttles”—meaning the system has reached capacity.
New York's “combined” sewer system—considered state-of-the-art when it was built
in the mid-nineteenth century—collects both runoff and sewage in one set of pipes.
(There were no wastewater treatment plants at the time, and there was no reason to
use separate sewage and storm-water pipes, as modern systems do.) To avoid massive
backups during storms, which could flood streets and basements with toxic sewage, re-
lief valves, called outfalls, allow the excess sewage to flow into local waters.
By the time the sewer pipes reach the Newtown plant , they are buried forty-five feet
beneath the surface. On a “dry weather day,” when the skies are clear, it requires only
four pumps to lift an average of 310 million gallons of wastewater per day from the
pipes. But during a heavy rainstorm—when five inches of water falls in thirty minutes,
say—all ten of the plant's giant pumps are put to work and can lift up to 700 million gal-
lons of water (usually composed of 450 million gallons of storm water and 250 million
gallons of sewage) in twenty-four hours, treat it, and release it into New York Harbor.
As the wastewater pouring into the plant reached 700 million gallons that January
night, Pynn grew concerned that the heavy flow was becoming dangerous: at that velo-
city, he said, “the water can literally erode away the sewer pipe.” He ordered the throt-
tling of eight gigantic gates—four at the Thirteenth Street pump house in Manhattan,
four at the NCWWTP in Brooklyn—which diverted, or “tipped,” the wastewater into
outfalls around the city: raw sewage began to spew into New York Bay.
Such an event, known as a combined sewer overflow (CSO), is distressingly common.
As little as one-twentieth of an inch of rain can be enough to cause the sewers to over-
flow, according to Riverkeeper. The city reports that 460 CSOs discharge more than 27
billion gallons of untreated waste-water into New York Harbor every year.
The effluent from CSOs has been found to contain human feces, high levels of co-
liform bacteria, forty types of disease-causing pathogens, viruses, industrial solvents,
debris, metals, nuisance levels of “floatables,” pesticides (such as malathion, an insect-
icide used to combat West Nile virus and the suspected cause of massive lobster die-
offs in Long Island Sound), and the like. CSOs can result in water quality problems, low