December 5, 2018

Additional Sewer Capacity helps to Reduce Flooding during Heavy Rain while also Improving the 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 Vincent Sapienza today joined with Department of Design and Construction (DDC) Commissioner Lorraine Grillo to announce that construction has been completed on the first phase of installing high-level storm sewers along 3rd Avenue in the Gowanus neighborhood. The additional capacity in the neighborhood’s drainage system is helping to reduce roadway flooding and the amount of pollution that may be discharged into the Gowanus Canal during heavy rainstorms. Phase I began in the spring of 2016, cost $26 million, and was completed in November. Work on Phase II is now under way, will cost $27 million, and will be completed in 2021. While the roadway is open to build the sewers, new water mains are also being installed. Funding for the project is provided by DEP while DDC is managing the construction.

“Third Avenue has been a chronic flooding location for many years and this $52 million investment will go a long way towards improving conditions for both residents and businesses,” said DEP Commissioner Vincent Sapienza. “With the installation of dedicated storm sewers, this project is already helping to reduce combined sewer overflows and improve the health of the Gowanus Canal.”

“This project is another major investment by the de Blasio Administration to improve the City’s environment and enhance its quality of life,” said DDC Commissioner Lorraine Grillo. “The completion of these upgrades addresses local street conditions as well as water quality conditions in the Gowanus Canal and surrounding waterways. It also makes the water delivery infrastructure more reliable and more resilient. DDC will keep working with its partners at DEP to bring projects like these to neighborhoods in every borough.”

“Upgrading storm sewer infrastructure has long been a critical priority for our Gowanus community, particularly along and around the Third Avenue corridor that too regularly floods during heavy rains,” said Brooklyn Borough President Eric Adams. “Street flooding and pollution discharge to the canal is a real concern for businesses and residents in this growing neighborhood, and the progress of work to alleviate this chronic issue is welcome news. I look forward to DDC and DEP’s completion of this drainage system project in Gowanus, as well as continued efforts on their green infrastructure initiatives along the canal.”

During the first phase of the project, more than 4,800 linear feet of new high-level storm sewers were installed along 3rd Avenue, between Carroll and Douglass streets, as well as portions of Denton Place and President, Union, Sackett and DeGraw streets. The construction of nine storm chambers and 48 new 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 high-level storm sewers. This will ensure that more wastewater is routed to a wastewater treatment plant and reduce the likelihood and volume of any combined sewer overflows into the Canal.

While the roadway was open to construct the sewers, approximately 5,000 linear feet of new ductile iron water mains were added to replace older cast iron pipes. This will ensure the reliability of the water delivery system for decades to come while 16 hydrants will provide firefighters with ready access to the City’s water supply. Upon construction’s completion, the roadways were resurfaced and new sidewalks, pedestrian ramps and curbs were installed. Tree planting is scheduled to take place during the next planting season, in the spring of 2019.

This project is the latest in a series of steps DEP has taken to improve the water quality of the Gowanus Canal. In late 2013, DEP reactivated the Gowanus Canal Flushing Tunnel for the first time since it was shut down for a full, $177 million rehabilitation in 2010. 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 allow 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. The activation of the flushing tunnel has already increased the dissolved oxygen content of the water in the Canal, which has improved its aesthetics as well as providing a more suitable habitat for plant and aquatic life.

DEP is also building green infrastructure throughout the Gowanus Canal drainage area. Green infrastructure allows stormwater to be naturally absorbed into the ground, thereby keeping it out of the sewer system where it could contribute to overflows into the Canal. This includes nearly 70 curbside rain gardens and two green playgrounds. DEP is also designing green infrastructure upgrades for the Gowanus Houses.

DEP manages New York City’s water supply, providing more than 1 billion gallons of high quality drinking water each day to more than 9.6 million residents, including 8.6 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 has nearly 6,000 employees, including almost 1,000 in the upstate watershed. In addition, DEP has a robust capital program, with a planned $19.4 billion in investments over the next 10 years that will create up to 3,000 construction-related jobs per year. 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 de Blasio’s long-term vision of growth, sustainability, resiliency, equity and healthy living, DDC provides communities with new or renovated public buildings such as such as firehouses, libraries, police precincts, and new or upgraded roads, sewers and water mains in all five boroughs. To manage this $14 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.