New Yorkers who have never laid eyes upon — or never heard of — the rainwater-capturing, urban runoff-reducing miracle worker known as the bioswale are about to get mighty familiar with this super-beneficial landscaping element that, outside of the Big Apple's impervious streetscapes, can commonly be found abutting gas stations, fast food joints and strip mall parking lots.

For the uninitiated, GrowNYC defines bioswales as “linear, sloped retention area designed to capture and convey water, while allowing it to infiltrate the ground slowly over a 24 to 48 hour period.”

Earlier this week, the New York City Department of Environmental Protection (DEP) announced plans to install a whopping 2,000 of the trench-like rain gardens in the outer boroughs. While Manhattan might have more available cabs and places to eat ramen at 2 a.m., Brooklyn, the Bronx and Queens (sorry, Staten Island) will have bioswales. Lots and lots of them.

The Big Apple’s pretty new bioswales, built into city sidewalks much like standard tree pits and more modest in size than their suburban brethren, will join about 250 of these aesthetically pleasing drainage ditches that have already popped up around the city as part of the city’s stormwater management-focused Green Infrastructure Program. The price tag attached to this aggressive — and much needed — onslaught of vegetated swales is $46 million.

While that might seem like a hefty wad of cash for the city to dedicate to curbside rain gardens, it’s nothing compared to the costs associated with upgrading New York’s aging combined sewage system (a system that handles both storm runoff and domestic sewage) and cleaning up after perfectly foul combined sewage overflow (CSO) events that strike following heavy rainstorms (and, of course, hurricanes).

As I described back in 2011 in a post about Leif Percifield’s Internet-based DontFlushMe sewage level alert system, a CSO occurs when a combined sewer system is inundated with stormwater during precipitation-heavy weather events. With nowhere to go but out, city wastewater treatment plants are forced to discharge a fetid mixture of storm runoff and untreated sewage into local waterways including, most notoriously, Brooklyn’s Gowanus Canal.

The DEP also singles out Newtown Creek, Jamaica Bay, the Bronx River and Flushing Bay as bodies of water that will benefit (read: be less frequently pumped full of raw sewage) from the presence of the new bioswales which will capture stormwater before it even has the chance to drain into the sewage system and wreak havoc.

While discharging raw sewage into local waterways at overflow points is by no means an ideal solution to dealing with overwhelmed combined sewage systems, the alternative would result in extensive damage to treatment plants along with something that you wouldn't even wish upon your worst enemy: sewage backups into homes and businesses.


Outside of dense urban areas, bioswales, like this one in Hinsdale, Ill., can be quite large. (Center for Neighborhood Technology/flickr)

In total, the DEP estimates that each bioswale will be able to manage between 1,300 and 3,000 gallons of runoff per storm and, collectively, capture an impressive estimated 200 million gallons of stormwater annually.

Remarks Brooklyn Borough President Eric Adams:

Bioswales are more than just a community beautification tool; they significantly improve our stormwater management while cleaning our environment. Some of our most important and at-risk waterways, including the Gowanus Canal, Jamaica Bay and Newtown Creek, will benefit from this effort, which is helping us become a more sustainable and resilient borough.

One of the dozen neighborhoods in Brooklyn where the bioswales will be constructed is Carroll Gardens, home to the EPA Superfund-ed Gowanus Canal.

“This is a crucial step to address the problem of combined sewer overflows, which remain a very serious problem for the Canal,” explains Brad Lander, the New York City Council Member who represents Brooklyn’s 39th Council District, which includes Carroll Gardens, Park Slope and other neighbors surrounding the Gowanus. “And this infrastructure is an example of the kind of creativity that will be required to help make the Gowanus neighborhood a model for sustainability in a low-lying, once-polluted industrial area, on a warming planet.”

In addition to Carroll Gardens, many of the bioswales, filled with trees, native vegetation and “hardy plants” to help aid in stormwater absorption, will be constructed in neighborhoods with both a dearth of greenery and high asthma rates, according to the DEP. In turn, in addition to bringing a splash of much-needed green to the concrete jungle and helping to prevent pollution from entering local waterways, these multi-tasking green spaces will also help New Yorkers suffering from health woes worsened by poor air quality.

Situated in locations selected by DEP engineers, the bioswales will be tended to weekly by Department of Parks and Recreation staffers. Aside from Carroll Gardens, additional neighborhoods in Brooklyn that will see new curbside sponges include, but are not limited to, Bushwick, Brownsville, Bedford-Stuyvesant and Crown Heights. Queens, Corona, Forest Hills and Jackson Heights will also have bioswales within the next several years. The targeted Bronx neighborhoods are Soundview, Clason Point and Castle Hill.

Do you have a bioswale (or something that you think might be one) in your neighborhood?

Via [Gothamist]

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Matt Hickman ( @mattyhick ) writes about design, architecture and the intersection between the natural world and the built environment.

Meet the bioswale, New York's new weapon in the war against water pollution
An army of bioswales — aka 'those weird sloped mini-gardens with pebbles' — will help prevent overwhelmed sewers from discharging waste into NYC waterways.