DEP Completes Construction of Underground Inflatable Dam in Red Hook

The city Department of Environmental Protection has finished construction of two inflatable dams in Brooklyn, one of which is located at Gold and Plymouth streets in Red Hook and is remotely monitored by Red Hook Wastewater Treatment Plant. The other dam is located at Kent Avenue and S. 5th Street in Williamsburg.

The underground dams are designed to prevent combined sewer overflow (CSO) from being discharged into New York Harbor. During heavy rains, the device inflates and stores a mix of stormwater and wastewater, which is later diverted to the wastewater treatment plant.

"We at DEP and New York City as a whole have been taking a look at what we can do to reduce those discharges of combined sewer overflows," said Vincent Sapienza, the Deputy Commissioner of Waste Water Treatment. "Inflatable dams are contrived to use existing sources to store flow during wet weather, and then, once that storm is over, to take that flow and put it to a waste water treatment plant so that it's treated rather than discharged as raw sewage."

The $15.7 million project will prevent up to 100 million gallons of combined sewer overflows from entering the harbor each year, with each dam able to store over 2 million gallons during a storm.

"The technology for inflatable devices like dams have been around for awhile, but it's really the control logic and the computer systems that make these dams effective," said Sapienza. "We've tested these for the last few years and it's at the point now where the devices themselves and the sensors that control whether or not they are inflated or deflated really are foolproof."

The construction of these devices is part of the NYC Green Infrastructure Plan, which includes several initiatives to improve the city's sewer system. The Plan has proposed a $2.4 billion investment to reduce CSOs, which have already been drastically reduced in recent years. In the 1980s, only 30 percent of overall flow was prevented from discharging into the harbor, as opposed to 72 percent today.

"The waterways around New York City have really been improved. In fact, they are the cleanest that we've measured them in a hundred years," said Sapienza. "That's really been due to the big investment New Yorkers have made to wastewater treatment plants."