Tuesday, June 4, 2013

Bioswale Installation Will Slow Down Stormwater Runoff In City

The Department of Environmental Protection plans to install 5,500 curbside gardens, called bioswales, to intercept, absorb and filter storm runoff before it flows into waterways. The bioswales will help clean up its rivers, streams and bays.  The bioswales—20 feet long and five feet wide—can hold 2,244 gallons of storm water at a time, the city says. They stretch five feet deep and are filled with broken stone and soil that contain air pockets to hold storm water. Planted with vegetation, the bioswales could pass topside as simple street gardens.

The bioswales, which cost about $25,000 each, will be tended by the city's parks department. Some 119 already have been installed in Queens and the Bronx around Jamaica Bay, the Hutchinson River and the East River. By 2014, city officials say they plan to have 2,200 bioswales installed, and 5,500 by 2015. Most will be situated in Queens, Brooklyn and the Bronx.

The bioswales are part of a larger city push on so-called green infrastructure, required under a 2012 settlement with New York state. In addition to paying a $200,000 fine to Albany for discharging pollutants into state waters, the city will spend some $5.3 billion to improve its sewer-overflow systems over the next 20 years.

By diverting storm water, the bioswales are designed to ease pressure on the city's 14 water-treatment plants, the final destination for both sewage water and storm-water runoff. On days with heavy rainfall, those plants become overwhelmed, letting wastewater and sewage slip into the city's waterways.

The city collects and treats 1.3 billion gallons of sewage and storm water on a dry day, city figures show, though the system can handle 2.5 billion gallons. Rainy days send far more than 2.5 billion gallons toward the treatment plants, the city says. (WSJ, 6/3/2013)

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