Turning Rain Into A Resource, Not A Pollution Source

by Peter Lehner, via NRDC’s Switchboard

New York City, like hundreds of older cities around the country, can’t stand the rain. With so much paved area, and so little ground to soak up the water, the city’s sewer system can get overwhelmed by a mere tenth of an inch of rainfall, triggering the discharge of polluted runoff from streets mixed with untreated sewage into the nearest water body. Anyone who’s walked along the Hudson River the morning after a storm knows what this looks like.

For New York, excess stormwater is one of the biggest sources of water pollution in the city. It’s a 30-billion-gallon-a-year problem.

The traditional approach to stormwater management is to treat it like garbage, as waste that needs to be disposed of. But a growing number of cities have recently embraced an innovative new approach to stormwater that transforms this “waste” into a resource that will improve neighborhoods. By building out a suite of solutions known as green infrastructure–including features like porous pavement, street plantings, and green roofs—city landscapes can absorb rainwater where it falls.  Instead of washing straight into the sewer system and triggering sewage discharges, this water can be used as nature intended, to nurture trees and plants, keeping neighborhoods cooler, greener, and the air cleaner.

This street planting outside a Brooklyn playground is one of the city’s pilot projects. By expanding the planted area around a streetside tree, using native plants and specially engineered, absorbent soil, city engineers have created a system that can absorb nearly 1,000 gallons of stormwater runoff, which would have previously been mixed with sewage and ejected directly into Jamaica Bay. The tree box also has extra storage chambers underground, which can hang on to extra water and slowly release it for the trees to drink.

The city plans to eliminate 1.5 billion gallons of water waste each year through green infrastructure, and aims to save billions of dollars as compared to the cost of building conventional “gray” infrastructure, such as pipes and large storage tanks.

“It’s particularly important for the State and City to leverage innovative, cost-effective solutions like these when there are competing social needs and taxpayer dollars must deliver more services for less, said city councilman James F. Gennaro, who supported the plan. Business leaders are on board with the effort as well, praising its cost-effectiveness and the use of public and private properties for stormwater management.

Philadelphia has an even more ambitious green infrastructure plan, and other cities are exploring the idea as well. Using green infrastructure to stop water waste is a radical departure from the norm, and it’s incredibly encouraging to see the idea take root. Stopping waste, even though it makes perfect sense, sometimes requires a change in thinking–and when it happens, the ripple effects can spread far and wide.

Peter Lehner is Executive Director of the Natural Resources Defense Council. This piece was originally published at NRDC’s Switchboard and was reprinted with permission.


10 Responses to Turning Rain Into A Resource, Not A Pollution Source

  1. squidboy6 says:

    Parking lots, streets, and similar paved spaces need to have holes poked through them to allow water to percolate down into the soil. This may be less feasible in NYC itself but that shouldn’t stop it from happening elsewhere.

    This could improve drinking water and reduce flooding all the way down the Mississippi River, besides creating jobs and making life better.

    Water is great temperature buffer, it resists rapid changes in temperature, so keeping it around but not in a standing pool of temporary conditions can help cut energy use.

    I like just being near water and it helps to focus the mind. Having more of it beneath my feet makes me feel better!

  2. Leif says:

    Catch the Rain at the tops of the buildings and use the “head” for electrical generation. Discharge directly into the streams or use for irrigation. String additional catchment reflective sheets between buildings to shade streets as well as reflect sunlight when it is not raining.

  3. fj says:

    Yes, rain is a tremendous free resource and it’s long overdue that we stop wasting and use it for terrific benefit.

  4. Doug Bostrom says:

    Our house backs on a creek that drains much of NE Seattle. Pavement is over 30% of the drainage for the watershed; the creek balloons with street runoff whenever it rains more than a drizzle.

    As a little example of easy improvements, our home’s gutters used to empty into pipes leading to the creek bank, thus bypassing any chance of water from the roof soaking into the ground. We dug a couple of drywells while do some other work on the property. Water now only emerges from the streamside pipes at the end of winter. This technique will work in a lot of places where gutters lead to the street or (legacy) directly into sewers.

    Obviously the ground needs some “perc” for a drywell to accept water. YMMV.

  5. AA says:

    Useless for power generation.

  6. Leif says:

    I disagree. Capture the water high, tops of big buildings, and put it in a pipe, you get head pressure. Use a large storage tank with a BIG HEAVY piston to retain the head pressure and use it as available. Use river water and surplus solar PV etc to pump the head higher as well for energy storage of PV. The storage piston could even be built below ground to retain pressures and simplify construction.

  7. AA says:

    It’s just not enough electricity to bother collecting.

    I’ve done this calculation before, but for “fun” I did it again, using NYC’s late twin towers as an example.

    Large roof area. Very Very tall. Reasonably rainy climate. Use both towers.

    How much could electricity could a downspout power turbine theoretically generate under these conditions?

    Using both towers, you could generate enough electricity to run one average American house.

    It would be fun to do, but it’s not worth pursuing as practical matter.

  8. Leif says:

    The major area is between the buildings, as I pointed out., tension cables with large collection material strung over the road ways. That would shade the streets and lower AC usage. Make bike travel more practical, reflecting sunlight increasing albedo, decreasing solar gain. All that is energy. Perhaps even incorporating solar PV in the sheets. Pumped hydro to lift the piston during excess production reversing to produce power during need. Add the weight of the “used” water to the top of the piston and no water even needs to be wasted and would increase head pressure of the remaining. Snow removal negated for the most part producing further energy savings. It all adds up.

  9. AA says:

    It does not add up.

    If you want to shade streets, that idea will have to stand or fall on its own merits. Using your canopy as a hydro-power catchment area is more trouble than it’s worth.

    It is a fun idea though. Bucky Fuller would approve.

  10. Leif says:

    Just brain storming. Mental gymnastics if you will.