When it rains in New York City it pours… sewage.
Less than an inch of rain can overwhelm America’s largest city’s drainage system, discharging raw sewage into the Hudson River, Long Island Sound, and surrounding wildlife refuges. It’s a 30-billion-gallon-a-year problem. But the emerging solution is rethinking stormwater as waste rather than a resource.
"It’s a complete paradigm shift in how we think of the 'problem’ of stormwater," writes Peter Lehner of NRDC. "Instead of trying to get rid of this 'excess’ water as fast as possible, we are turning it into an opportunity to make cities more livable places, with cleaner air and greener neighborhoods."
For a century, the solution to stormwater has been to put it into underground pipes as soon as possible. In New York, and about 800 other cities where one set of pipes handles both liquid waste and runoff, a major rainfall forces municipalities to simply dump it all into the nearest waterway.
New York, along with Philadelphia, is now taking a different approach by investing billions in infrastructure such as street plantings, porous pavements, and green roofs that will store, slow, and absorb the water. Tree boxes that expand the area around trees and add absorbent soil already going up around the boroughs. New York’s Department Environment Conservation estimates it will avoid two billion gallons of water per year entering the drainage system and save $2.4 billion slate to have "grey" infrastructure handle that volume of water.
New York City, despite being one of the most urbanized regions in the U.S., has always been among the first to pay for the value of ecosystem services—the benefits furnished by the natural environment—over new, more expensive infrastructure. The most famous case was securing the city’s water supply in 1997 when the city launched a $1.5 billion program to preserve its watershed in upstate New York, which ended up cutting about $8 to $10 billion off the cost of new water treatment plants.
So billions for better sidewalks and roofs now may come to seem like a very good deal in the future, when the Hudson is filled with water and not sewage.