July 12, 2023

Additional Capacity in Neighborhood’s Drainage System Reduces Flooding During Heavy Rainstorms While Also Improving Health of the Gowanus Canal

A Map of the Project Area and Photos of the Work are Available on DEP’s Flickr Page

New York City Department of Environmental Protection (DEP) Commissioner Rohit T. Aggarwala today joined with Department of Design and Construction (DDC) Commissioner Thomas J. Foley and Deputy Mayor of Operations Meera Joshi to announce that construction has been completed on the $54 million installation of new storm sewers along 3rd Avenue in the Gowanus neighborhood. The additional capacity in the neighborhood’s drainage system is already helping to reduce roadway flooding and the amount of pollution that may be discharged into the Gowanus Canal during heavy rainstorms. Funding was provided by DEP while DDC managed the construction.

“These drainage improvements proved their worth most recently during the 4th of July rainstorms, as DEP received no reports of sewer backups or street flooding along 3rd Avenue,” said DEP Commissioner Rohit T. Aggarwala. “DEP continues to explore stormwater management solutions for other corridors in Gowanus that experience regular flooding.”

“This $54 million project is another major investment in Brooklyn which will improve harbor water quality while also helping to reduce the effects of intense rainfalls that can cause local flooding,” said NYC Department of Design and Construction (DDC) Commissioner Thomas Foley. “Gowanus is a vulnerable area and we’re proud to help improve the situation for residents. Larger sewers are just one approach to managing climate change. DDC and DEP are developing new infrastructure within the Mayor’s Cloudburst Resiliency Program that includes not just larger sewers but also thousands of curbside rain gardens and now the use of porous pavement that allows for better natural stormwater drainage.”

“Upgrading and expanding our underground infrastructure is one of the most effective tools we have against excessive water, protecting communities from heavy rainstorms and torrential floods,” said Deputy Mayor of Operations Meera Joshi. “By increasing the capacity for rainwater with larger and separate storm sewer pipes, DEP provides critical protection for the Gowanus community.

Before work began, drainage for the area around 3rd Avenue was routed to a single combined sewer pipe, which collected both wastewater from surrounding homes and businesses as well as stormwater from the street. The main component of this project involved building a new sewer pipe under 3rd Avenue to carry only stormwater. This dedicated stormwater pipe improves roadway drainage while also creating additional capacity for wastewater in the existing combined sewer, which reduces the chance of any polluted overflows into the nearby Gowanus Canal.

Construction was completed over the course of two capital projects with Phase 1 starting in March 2016 and Phase 2, which ended this month, starting in October 2018. Design of the two projects was also completed in-house by DDC’s Infrastructure Design team, reducing costs for the overall program, which completed the City work on budget.

“The completion of the 3rd Avenue high-level storm sewers marks a new chapter in Gowanus’ history. Modernizing our city’s infrastructure is imperative, especially in areas that have suffered unfortunate health and safety issues for generations, like Gowanus,” said Brooklyn Borough President Antonio Reynoso. “Thank you to DEP and DDC for leading efforts to upgrade infrastructure.”

“I am thrilled at the news of the Gowanus high-level storm sewers finishing construction, a desperately needed infrastructure upgrade that will reduce flooding and protect the Gowanus Canal from more pollution and waste. I would like to thank DEP Commissioner Rohit T. Aggarwala for prioritizing the health and safety of the Gowanus community,” said Assembly Member Jo Anne Simon.

“Investments in high-level storm sewers will protect the Gowanus Canal from further pollution and protect our neighborhoods from future flooding. This action helps build our community’s resiliency as we work to tackle the climate crisis,” said Council Member Lincoln Restler.

“Gowanus residents have been inundated with flooding year after year but thanks to this $54 million investment by the Department of Environmental Protection, our neighbors will have the infrastructure to ensure their homes stay dry,” said City Council Member Shahana Hanif. “With climate change becoming a more ever-present reality for our coastal community, upgrading our storm sewage capacity is essential to building resilient communities. I’m deeply grateful to the City for making this critical investment now and not waiting for the next big storm.”

As part of construction, more than a mile (7,118 linear feet) of new storm sewers were installed along Third Avenue, between Carroll and State Streets, as well as from 3rd to 4th Avenues for each of the east/west streets between Carroll and State Streets. The construction of nine storm chambers and 74 catch basins will help to drain precipitation from the roadways and alleviate localized flooding. Existing catch basin drainage connections were switched from the combined sewer to the new storm sewer. This will ensure that more wastewater is routed to a wastewater treatment plant.

While the roadway was open to construct the sewers, more than two miles (10,820 linear feet) of older cast iron pipes were replaced with concrete-lined ductile water mains, which are more resilient and less prone to breakage than the cast iron pipes typically used decades ago. This will ensure the reliability of the water delivery system for decades to come while 36 new fire hydrants will provide firefighters with ready access to the City’s water supply. Upon completion of the sewer and water work, the roadways were resurfaced and new sidewalks, pedestrian ramps and curbs were installed.

This is the latest in a series of steps DEP has taken to improve the water quality of the Gowanus Canal. In March, DEP joined with Mayor Eric Adams and U.S. EPA to break ground on the $1.6 billion sewer overflow retention tanks that will help to protect the ongoing Superfund Cleanup of the Canal.

DEP also completed a full, $177 million rehabilitation and upgrade of the Gowanus Canal Flushing Tunnel. The Flushing Tunnel brings more oxygenated water from Buttermilk Channel, lying between Governors Island and Red Hook, to the head of the canal. The rehabilitation work included draining the 1.2-mile long, 12-foot diameter tunnel and inspecting and repairing its brick-lined interior. The installation of three new turbine pumps allows for the injection of as much as 252 million gallons of fresher water into the Canal each day, or roughly 30 percent more than it could before the upgrade. In addition, the tunnel can now operate around the clock, including at low tide, when the Canal water is at its most stagnant.

DEP has also built green infrastructure throughout the Gowanus Canal drainage area. This includes nearly 70 curbside rain gardens and Green Infrastructure playgrounds at P.S. 282 in Park Slope and P.S. 38 in Boerum Hill. Green infrastructure allows stormwater to be naturally absorbed into the ground, thereby keeping it out of the sewer system where it could contribute to flooding and overflows into the Canal. DEP has also built nine green infrastructure installations for the Gowanus Houses that will capture nearly 2 million gallons of stormwater in a typical year. The project will ease pressure on the neighborhood’s sewer system during rainstorms, which will decrease overflows into the Gowanus Canal.

DEP manages New York City’s water supply, providing approximately 1 billion gallons of high-quality drinking water each day to nearly 10 million residents, including 8.8 million in New York City. The water is delivered from a watershed that extends more than 125 miles from the city, comprising 19 reservoirs and three controlled lakes. Approximately 7,000 miles of water mains, tunnels and aqueducts bring water to homes and businesses throughout the five boroughs, and 7,500 miles of sewer lines and 96 pump stations take wastewater to 14 in-city treatment plants. DEP also protects the health and safety of New Yorkers by enforcing the Air and Noise Codes and asbestos rules. DEP has a robust capital program, with a planned $31.3 billion in investments over the next 10 years. For more information, visit nyc.gov/dep, like us on Facebook, or follow us on Twitter.

The Department of Design and Construction is the City’s primary capital construction project manager. In supporting Mayor Adams’ long-term vision of growth, sustainability, resiliency, equity and healthy living, DDC provides communities with new or renovated public buildings such as firehouses, libraries, police precincts, and new or upgraded roads, sewers and water mains in all five boroughs. To manage this $24 billion portfolio, DDC partners with other City agencies, architects and consultants, whose experience bring efficient, innovative and environmentally-conscious design and construction strategies to City projects. For more information, please visit nyc.gov/ddc.