Bioswales to divert CB10, 11 rainwater

A bioswale in Brooklyn collects stormwater.
Photo courtesy of the NYC Department of Environmental Protection

Community boards 10 and 11 will soon be getting greener.

The NYC Department of Environmental Protection has brought its green infrastructure program to the Bronx.

Bioswales, greenspaces in the sidewalk designed to collect stormwater, will be installed throughout the Westchester Creek watershed in the eastern part of the borough.

The green infrastructure initiative, started in 2011, is a city-wide effort by DEP to improve water quality in the city by reducing the amount of stormwater that ends up in the city’s century-old sewer system, where it mixes with sanitary water.

During or after heavy rains, water from the sewer exits the system at designated points into the city’s waterways in order to avoid overwhelming the wastewater treatment centers.

Those ‘combined sewer overflows’ is what green infrastructure is designed to reduce, by keeping some rainwater out of the sewer system.

Types of infrastructure can include green roofs, rain barrels, greenstreets in under-utilized roads space or bioswales in the sidewalk.

The bioswales are about 5 feet deep, filled with an engineered mix of rock and sand, and topped with plants. They are placed upstream of catch basins, and cuts in the bioswales’ curb aim to divert water running down the street into the greenspace where it will be stored and used by the plants. A tree guard protects the other three sides of the space.

A representative from DEP presented the information about the forthcoming infrastructure to Community Board 11’s leadership committee on May 18 to bring them up to date on the already-in-process project.

After conducting hydraulic analysis in the area and walking through with DOT to identify feasible areas, the DEP has been drilling at potential sites to take soil samples to determine the best sites for the bioswales.

They expect to be drilling for several more months, and to have a list of sites for construction in the Westchester Creek watershed by the end of the year, the representative said.

The process to bring bioswales to the Bronx River watershed in the western part of the Bronx will begin later this year.

Members of CB 11’s Leadership Committee were receptive to the idea of green infrastructure overall, but were wary of the $25,000 price tag for each bioswale that will be paid for by revenue from the city’s water rates.

“I disagree with the amount of money they’re going to spend,” said board member Joe McManus after the meeting.

McManus said he’s concerned that the bioswales won’t divert enough water to compensate for the larger infrastructure deficiencies.

“Basically they’re little sponges,” he said.

CB 11 vice-chair Al D’Angelo said he was also concerned that the middle class would ultimately bear the cost of the infrastructure, but said that overall the bioswales sounded like a good idea.

“It would beautify the city,” he said.

Reach Reporter Jaime Williams at 718-260-4591. E-mail her at jwilliams@cnglocal.com.
Bioswales, greenspaces in sidewalks designed to collect stormwater, like these in Brooklyn will be coming to Community Board 11.
Photo courtesy of the NYC Department of Environmental Protection

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