NYC announces suite of stormwater infrastructure initiatives

Sept. 6, 2022
From green infrastructure to flood sensors and beyond, New York City has announced massive stormwater infrastructure projects following the one-year anniversary of Hurricane Ida.

New York City Mayor Eric Adams and the New York City Department of Environmental Protection (DEP) marked the one-year anniversary of Hurricane Ida by announcing a suite of stormwater infrastructure initiatives aimed at making the city more resilient to extreme rainfall in the future.

The announcement took place on Sept. 1 in South Ozone Park, Queens, where the city recently completed the construction of 2,300 new curbside rain gardens. For more than a century, New York City’s network of catch basins and sewers have served as the primary drainage tool across the five boroughs. As New Yorkers continue to experience the increasing impacts of climate change, the city is accelerating plans for a multi-layered system of adaptive infrastructure that will make the city more resilient to Ida-level rainstorms, and an implementation plan to guide this long-term effort is underway.

“One year ago, Hurricane Ida brought the heaviest rainfall in our recorded history and flooded our streets, subways, and basements, and, worse, claimed the lives of 13 of our neighbors,” said Mayor Adams. “Our neighbors were victims of climate change, which is bringing longer droughts, stronger storms, and heavier rainfall to places all over the globe, but we will not simply stand by and do nothing. We are taking action to protect our city and prevent future tragedies, by ramping up flood protection with sewer advancements and curbside rain gardens, as well as by building out our cloudburst infrastructure and expanding other flood mitigation options, including the bluebelt drainage system. New York City is adapting to the realities of climate change in real time and doing everything we can to keep New Yorkers safe and honor all that we lost one year ago today.”

“The Department of Design and Construction is proud to be part of a multi-agency effort addressing the wide-ranging impacts of climate change, including events like Hurricane Ida,” said New York City Department of Design and Construction (DDC) Commissioner Thomas Foley. “We are building new sewers in parts of the city that didn’t have them, increasing capacity to handle heavier rainfall events in others, rolling out innovative efforts to divert stormwater away from our sewer system, and installing thousands of green infrastructure projects across the five boroughs. Our work is not done, and we are finding ways to actually accelerate delivery so we can bring these projects online even faster in the future.”

Sewer Infrastructure

DEP is working with the DDC to upgrade and build out the sewer system to modern standards. In Southeast Queens, the city is investing $2.5 billion to install upgraded sewers. DDC is working in Gowanus, Brooklyn to complete a $39 million storm sewer project that will lead to cleaner water in the canal and reduce flooding in that area. Completion is scheduled for November 2022.

In the neighborhoods of Woodside, Maspeth, Middle Village, and Glendale in central Queens, the city has completed several projects to eliminate chronic flooding. The city is currently using micro-tunneling technology to double the size of sewers and reduce or eliminate flooding. This $119 million project is expected to be completed in 2023.

The city also completed a $47 million project to raise streets and add almost half a mile of new storm sewers to reduce flooding in Broad Channel, Queens — an area frequently inundated by Jamaica Bay during high tides and storms. Phase Two — an $83 million project that will add an additional 3,200 linear feet of new storm sewer on previously unsewered blocks — is anticipated to be completed in 2024.

To alleviate flooding in South Beach, Staten Island, the city completed a $98 million project that encompasses 61 individual blocks and includes the reconstruction of over three miles of storm sewers, ranging from 12 inches in diameter up to rectangular sewers that are 8.5 feet wide by four feet high. The work included the installation of 200 new catch basins to better capture stormwater and direct it to new storm sewers.

In Southern Brooklyn, the city completed a $166 million project that included the construction of 6.5 miles of new sewers. Building new sewers and separating previously combined sewers creates additional capacity in the drainage system to reduce flooding and cut sewer overflows into Fresh Creek by 189 million gallons annually.

Curbside Rain Gardens

New York City is also investing heavily in curbside rain gardens.

More than 70 percent of New York City is covered by impervious surfaces. The recent addition of 2,300 new curbside rain gardens is a milestone in the city’s effort to build out an aggressive green infrastructure program. More than 11,000 installations have already been constructed, and construction is set to begin on 1,000 more rain gardens by the end of this year.

The 2,300 newly constructed rain gardens are located across Queens and the Bronx. Each rain garden has the capacity to collect and absorb up to 2,500 gallons of water during each storm. It is estimated that newly installed green infrastructure will capture more than 369 million gallons of stormwater annually.

In Queens, a total of 1,811 rain gardens and infiltration basins now exist in Kew Gardens Hills, Hillcrest, Fresh Meadows, Utopia, Flushing, Murray Hill, and Auburndale. It is estimated the newly added rain gardens will capture more than 264 million gallons of stormwater annually, helping to reduce the risk of flooding for residents and businesses in the area, while also improving the health of Flushing Creek and Flushing Bay.

In the Bronx, 565 rain gardens and infiltration basins were installed in Belmont, Crotona, West Farms, Van Nest, Westchester Square, Morris Park, Pelham Gardens, Pelham Parkway, Allerton, Laconia, Williamsbridge, and Olinville. Modeling shows these assets will manage approximately 105 million gallons of stormwater annually, reducing the risk of flooding while also improving the health of Westchester Creek and the Bronx River.

FloodNet Sensors

NYC FloodNet is a new flood data collection program that will provide real-time street-level flood information to city agencies, residents, emergency response teams, and researchers. The information provided by the sensors can give critical information on the need for road closures or travel bans, inform residents of the need to deploy sandbags and flood barriers, validate existing flood models, and provide data for future drainage investments.

The city has already installed 29 sensors this year alone, will install 50 this year, and will install 500 FloodNet sensors in priority areas citywide over the next five years. These areas are determined by an analysis of stormwater risk, tidal flooding risk, storm damage, environmental justice history, social vulnerability, critical infrastructure, and proximity to wireless network connections.

Cloudburst Management

New York City has been partnering with the city of Copenhagen to share best practices for stormwater management. An outgrowth of that work in New York City are pilot cloudburst projects to help manage extremely intense cells of rainfall that can impact portions of the city during a storm. These intense rain events can drop a large amount of water over a short period and can overwhelm the city’s sewer system capacity.

Cloudburst management implements a combination of methods that absorb, store, and transfer stormwater to minimize flooding. The city’s new cloudburst projects will seek to utilize open spaces to store stormwater until the rainfall event passes, and there is capacity in the drainage system to manage it.

The city’s first cloudburst pilot project will take place at NYCHA’s South Jamaica Houses. Project design is now complete, and construction is expected to begin in 2023. The city is expected to invest $4-5 million on this project and will focus on channeling stormwater to three areas on the NYCHA grounds: Two open grassy areas that will be designed to hold a large amount of stormwater and a basketball court that will be rebuilt at a lower elevation so water will naturally flow there.

When completed, this cloudburst installation will capture and hold approximately 300,000 gallons of stormwater. In addition, upgrades will be made to complement this work, including new lighting and seating.

Another cloudburst pilot project at the St. Albans/Addisleigh Park neighborhood in Southeast Queens is currently in design. NYCHA’s Clinton Houses in East Harlem, Manhattan has also been selected for a cloudburst pilot project. This project — currently in design — is the recent recipient of an $8.31 million grant from the federal government.

Citywide Bluebelt Program Expansion

The city remains committed to expanding its Bluebelt Program. Bluebelts utilize existing streams, ponds, and wetlands and partner them with storm sewers to safely drain large volumes of stormwater and naturally filter it before eventually flowing to the New York Harbor. Today, there are 94 bluebelts citywide, with 83 providing drainage for more than a third of Staten Island, 10 in Queens, and one in the Bronx. There are several additional bluebelts currently in the pipeline, and DEP engineers are looking across the city to determine what sites are feasible for future bluebelts.

Daylighting

The city has begun an ambitious project to “daylight” parts of the southern section of Tibbetts Brook, south of Van Cortlandt Lake in the Bronx. This means bringing a previously buried stream back to the surface, redirecting the flow of the Tibbetts Brook out of the sewer system and allowing it to run closer to its historical course toward the Harlem River.

By daylighting Tibbetts Brook and removing its clean water from the sewer system, the project will create additional capacity in the area’s sewer network and should help to mitigate flooding along Broadway and other areas of the Tibbetts Brook watershed, while also reducing sewer overflows into the Harlem River.

Tibbetts Brook is a small stream that begins its journey in the City of Yonkers and flows south into Van Cortlandt Park in the Bronx. The stream cuts through the middle of the park, where it was dammed to form Van Cortlandt Lake. Historically, Tibbetts Brook flowed through southern portions of the Bronx before emptying into the Harlem River. Roughly a century ago, however, this southern portion of Tibbetts Brook was redirected into the city’s sewer system at a rate of 4 to 5 million gallons per day on dry weather days, and the bed of the waterway was reclaimed for other purposes. The freshwater of Tibbetts Brook then travels through the sewer system, occupying space that could otherwise be used by stormwater to the Wards Island Wastewater Resource Recovery Facility.

Porous Pavement

As part of an ongoing pilot program, more than three miles of porous pavement have been installed within roadways in Queens and the Bronx. Porous pavement manages more stormwater runoff than typical curbside rain gardens and is easier to site. Engineers are currently designing more than 56 additional miles of porous pavement for Brooklyn and the Bronx.

Onsite Retention

Earlier this year, DEP finalized the Unified Stormwater Rule, which requires any newly developed or redeveloped property to include infrastructure, such as a green or blue roof, rain gardens, or storage, that will retain additional stormwater on-site. By keeping stormwater on-site, and not allowing it to drain onto sidewalks and eventually into the city’s sewer system, the new rule will help ease pressure on the sewer system, mitigate flooding, and reduce sewer overflows.

Flood Insurance and Financial Counseling

The city is expanding outreach and counseling to homeowners and tenants through FloodHelpNY, an online platform that provides residents with information and resources about flood risk, flood insurance, and flood resiliency retrofits. Since 2016, FloodHelpNY has educated and equipped more than 700,000 New Yorkers with resources to prepare themselves and their homes. The city has proposed a significant expansion of the program using federal grant funding that will help homeowners better prepare to recover from a flood. In addition to launching a coordinated marketing campaign around flood insurance, the city aims to leverage FloodHelpNY to offer in-home engineering inspections and financial counseling sessions for property owners in certain flood-prone neighborhoods.