Gowanus Canal Clean Up Update

Gowanus Canal Clean Up Update

Update: On April 15, 2016 the U.S. Environmental Protection Agency (EPA) and the NYC Department of Environmental Protection (DEP) reached in agreement on the location of two sewage and stormwater retention tanks in Gowanus: an eight-million gallon tank will be built on privately-owned property along the Canal, between Butler and Degraw Streets, and a smaller four-million gallon tank will be located on a City-owned property at 2nd Avenue and 5th Streets. You can read the full agreement here.


Black mayonnaise. Poo-nami.  Rumors of a three-eyed catfish.  

I know this update isn’t well-themed for the holiday season – I’m not aware of any Christmas carols about “combined sewer overflows” – but we wanted to give you an end-of-year update on the work to clean up the Gowanus Canal.

The Gowanus Canal has been deeply polluted for more than a century, making it a long-time source of local lore—and cringe-inducing headlines.

However, since the U.S. Environmental Protection Agency designated the canal as a “Superfund” site in 2010 (after longstanding advocacy by many local leaders), the Federal, State, and City government have all committed significant resources to reversing many decades of environmental degradation and neglect. Projects are underway that will, over the next several years: dredge the toxic sludge at the bottom of the waterway, curtail its use as an open sewer, remediate the land nearby, and minimize neighborhood flooding.

Here’s some of the progress toward a cleaner Gowanus that we’ve seen in the past year:

  • The dredge is on track to start in 2017 (as the primary part of the EPA’s Superfund project). You may have seen that, in the 7th Street basin, the EPA conducted a pilot study for different “caps” to seal the bottom of the canal after it is dredged.
  • The Gowanus Flushing Tunnel and Pumping Station (restored and operated by the NYC Department of Environmental Protection, or DEP) are fully functional, drawing cleaner water from Buttermilk Channel to “flush” the canal and pumping more wastewater to the treatment plant.
  • The EPA has ordered New York City to build two CSO (combined sewer overflow) retention tanks, which will go a long way to prevent the release of sewage in the Canal when it rains. There’s a debate underway about where to site the northern tank; but no debate that both tanks will be built.
  • Construction is underway on the first phase of new “high level storm sewers” along 3rd Avenue, which channel rainwater directly into the canal. These HLSS, built by NYC DEP, will increase the sewer system’s capacity, thereby reducing wastewater overflows into the canal and flooding in the streets.
  • Construction is also underway on new “green infrastructure” projects, which use plants to absorb rainwater, thereby reducing wastewater overflows and street flooding. They include 90 curbside gardens as well as a Sponge Park at the foot of 2nd Street.
  • The remediation of the contaminated land at 388 Carroll St and 365 Bond St is complete, and cleanups are in the works for 563 Sackett St, 450 Union St, and Bayside Fuel Oil. More sites will be cleaned up if and when there are development plans for them.

There’s more information on each of these projects below, if you'd like to read more about the clean up of the canal itself, the sewers, and the land.

We’ve got a very long way to go, of course. These projects will take the better part of the next decade. Meanwhile flooding, sewer back-ups, and the stench persist. But we are starting to see progress that will pay off in a big way in the years to come.

For this work, we owe big thanks to the US Environmental Protection Agency (and the Region 2 Superfund team), NYS Department of Environmental Conservation, NYC Department of Environmental Protection, and to a deeply committed group of local stakeholders known as the Gowanus Canal Community Advisory Group, or “the CAG” (whose website is a great source of updates on cleanup activities).

All of this cleanup work has served as an anchor for our Bridging Gowanus community planning process, launched in 2013, with the goal to develop a comprehensive framework for the infrastructure and land use regulations needed for a safe, vibrant, inclusive and sustainable Gowanus. Over a two-year process, substantial agreement emerged around a set of core values (and were affirmed by Community Board 6) that should shape any future actions in the neighborhood:

  • Upfront investments in sustainable infrastructure – for environmental cleanup of the water and land, to reduce flooding and to improve resiliency without creating adverse hydrological impacts, build new schools to address overcrowding, create and connect open space, and improve transit options.
  • Strengthening manufacturing businesses – recognizing the importance of retaining space for heavier industrial uses, as well as the opportunity that exists in the innovation, technology, green-tech, and creative sectors – and making sure residents can benefit from the jobs.
  • A genuine mixed-use community that preserves the character of Gowanus, including light manufacturing and the vibrant arts and artisan community, by strengthening protections and building those uses more strongly into the area’s zoning.
  • Preserving and creating affordable housing where new residential development is allowed – through investments in preserving public housing, stronger protections against tenant harassment and displacement, and mandatory inclusionary zoning – so the benefits of a resurgent Gowanus can be shared across lines of race and class.
  • Making sure the rules are followed – for sustainability, affordability, infrastructure, mixed-use, and quality of life – and aren’t simply words on paper amidst the loud reality of development.

While we work toward those goals (you can see the whole Bridging Gowanus community planning framework here), you can read more below about progress over the past year on the cleanup of the canal, the sewers, and the land.

We will continue to update you as these projects progress – and I look forward to continuing to work together with many community activists and our partners in government to get the biggest cleanup possible.

Sorry again for the near-holiday update on such an unlovely topic – but at least it’s better than coal (tar) in your stocking.




December 2015

Background: Two Very Different Sources of Pollution

The Gowanus Canal suffers from two major sources of contamination – each toxic in its own way. The first is a product of Gowanus’ industrial past. Beginning in the 19th century, the 1.8 mile-long canal was a transportation route for manufactured gas plants (MGPs), paper mills, tanneries, and chemical plants. There were three MGPs near the canal during this time, which supplied homes and businesses with gas for lighting, heating, and cooking. Coal tar is one byproduct of gas production that today is a major source of contamination in the canal and some of the land around it.

To add to the industrial pollution, the canal is also a long-time site of sewage overflows. In most of New York City, we have a combined sewer system, meaning the pipes that carry sanitary waste from our homes to treatment plants also collect rainwater from the street. During storms, rainwater can cause sewers to swell to capacity, overwhelming our wastewater treatment plants —and therefore triggering “combined sewer overflows,” when a mixture of rainwater and sewage is released into waterways.

On average, there is 10 feet of sediment that has accumulated at the bottom of the canal because of industrial pollutants and sewage overflows. That sediment is sometimes referred to as “black mayonnaise.” Testing has found the contaminants in the canal to include PCBs, coal tar wastes, volatile organics, and heavy metals like mercury, lead, and copper.

In September of 2013, the U.S. Environmental Protection Agency (EPA) finalized the “Record of Decision” for its Superfund cleanup plan:

  • Remove the accumulated contaminated sediment from the bottom of the canal by dredging and build a multi-layer cap to prevent coal tar from seeping up into the canal
  • In coordination with the State, remediate the land where the three MGPs stood and construct cut-off walls along the canal to prevent coal tar from seeping into the canal
  • In coordination with the City, construct two CSO tanks, to capture wastewater that today overflows into the canal during storms

The cost of the Superfund cleanup plan – projected to exceed half-a-billion dollars – will be paid by the parties found to be responsible for the contamination, which are anticipated to include National Grid (formerly Brooklyn Union Gas) and the City of New York.

You can find more detailed information about the Gowanus Superfund cleanup on the EPA's website.

(Want a video to explain it? The EPA made one of those, too)

Part 1: The Canal

The Dredge

The EPA has divided the canal into three areas based on the severity of contamination. The work is scheduled to begin in 2017 and be completed in 2022.

  • Area 1: Butler Street to 3rd Street
  • Area 2: 3rd Street to 9th Street
  • Area 3: 9th Street to 21st Street

Between Areas 1 and 2, the EPA plans to remove approximately 307,000 cubic yards of highly contaminated sediment and, from Area 3, approximately 281,000 cubic yards of contaminated sediment.

Good news: The dredge will also restore 500 feet of the canal! Historically, the Gowanus Canal had an arm at 1st Street (on the east side), known as the 1st Street Basin. The EPA will require removal of contaminated material placed there decades ago and restoration of the waterway. The EPA will also require that 25 feet of the 4th Street Basin (underneath the 3rd Avenue Bridge) be restored.

The Cap

Once the dredging is completed, the EPA will cap the bottom of the canal to prevent any pollutants from the surrounding land from seeping upwards. The cap will consist of three layers of clean material:

  • Active layer made of a specific type of clay that will remove contamination that could well-up from below
  • Isolation layer of sand and gravel that will ensure that the contaminants are not exposed
  • Armor layer of heavier gravel and stone to prevent erosion of the underlying layers from boat traffic and canal currents.

Clean sand will be placed on top of the armor layer to fill in the voids between the stones and restore the canal bottom as a habitat.

Where there is liquid coal tar in the land below the canal, the EPA will first stabilize the land by mixing it with concrete or a similar material, and then apply the three-layer cap.

The Sludge

Once the black mayonnaise is scraped from the bottom of the canal, we’ve got to do something with it. The sediment will be treated differently based on the severity of contamination. The highly contaminated sediments from Areas 1 and 2 will be treated at an off-site facility through a process called “thermal desorption,” which heats the sediment to temperatures that destroy contaminants. The resultant material might be reused, for example as landfill cover.

The less contaminated sediments from the first and third segments of the canal will be stabilized by mixing with materials like cement and might be reused offsite.

Part 2: The Sewers

In most of New York City, we have a combined sewer system, meaning the pipes that carry sanitary waste from our homes to treatment plants also collect rainwater from the street. During storms, rainwater can cause sewers to swell to capacity, overwhelming our wastewater treatment plants — and therefore triggering “combined sewer overflows,” when a mixture of rainwater and sewage is released into waterways.

Rainwater and sanitary waste from many neighborhoods drain down into the Gowanus Canal during overflows, including parts of Gowanus, Carroll Gardens, Boerum Hill, Park Slope, and Prospect Heights—meaning interventions to improve water quality in the Gowanus Canal must extend from the area immediately surrounding the canal to include other nearby neighborhoods.

Flushing Tunnel & Pumping Station

One important element of improving water quality in the canal over the past few years has been the $160 million overhaul and restoration of the Gowanus Flushing Tunnel and Pumping Station, which draws cleaner water from New York Harbor to “flush” the canal (and also includes a “counter-flow” tunnel that directs CSOs directly to the treatment plant).

Originally built in 1911, the Flushing Tunnel was constructed to pump contaminated water from the Gowanus Canal west toward Buttermilk Channel (the waterway between Brooklyn and Governor’s Island). The tunnel ceased functioning from the mid-1960 to mid-1990s, when it was reactivated and the flow reversed, bringing cleaner water from Buttermilk Channel east to “flush” the stagnant canal.

Earlier this year, NYC DEP completed the Gowanus Facilities Upgrade, with three new submersible pumps (instead of just one), increasing the tunnel’s flow capacity to 215 million galloons per day (up from 154 mgd). In addition, the City upgraded the Pumping Station, installing a brand new force main to pump wastewater to the Red Hook Wastewater Treatment Plant, to reduce the incidence of wastewater overflows. These upgrades are projected to reduce CSO discharge by 34%—a good start, but still with a long way to go.

Retention Tanks

To achieve further water quality improvements (and protect the Superfund cleanup for the long term), the US EPA has ordered – as part of the Superfund Record of Decision – that the City construct two underground retention tanks to capture wastewater (or CSOs) that today overflows into the canal during storms. The EPA estimates that the two new tanks will reduce overflows by between 58% and 74%. The EPA is working together with the City to make sure construction of the two tanks are phased with the Superfund dredge, so that sewage overflows do not recontaminate the canal.

The southern tank is expected to be constructed at the “Salt Lot,” a City-owned property at 2nd Avenue and 5th Street now used by the NYC Department of Sanitation and the Gowanus Canal Conservancy.

There is a significant debate about where the northern tank will be constructed. In June, the City discussed two primary options: under the Douglass & DeGraw Pool at Thomas Greene Playground (which will, in any case, be temporarily removed and reconstructed in order to excavate coal tar contamination); or on two privately-owned properties along the canal between Butler and Degraw Streets (which would be acquired or taken through eminent domain proceedings). The City of New York prefers the canal-side private properties, which would reduce the length of time the pool is closed, prevent any diminution of pool/park size for the tank, and create the opportunity for additional canal-front open space. Supporters of the pool site argue it would be faster, since no additional acquisition or eminent domain is needed.

The EPA will make the final decision in the coming months. While there is debate about the location, there is agreement that both tanks (north & south) will be built as part of the Superfund remedy.

High Level Storm Sewers

Construction is underway on the first phase of new “high level storm sewers” along 3rd Avenue, which channel rainwater directly into the canal, instead of into the existing combined sewer system. In this way, HLSS increase the existing sewer system’s capacity, thereby reducing wastewater overflows into the canal, and also reducing flooding on local streets – which has become an increasing problem along 4th Avenue and other local streets.

The HLSS will be constructed in two phases: Phase 1 (underway now) stretches along 3rd Avenue between Douglass and Carroll Streets (map of affected streets here), and Phase 2 (which will not start for several years) runs north from Douglass to State Street.

We have also been pressuring DEP to move more quickly to address street flooding on 9th Street (over the canal, between 2nd Avenue and Smith Street), and along 2nd Avenue, where flooding is a chronic problem when it rains, causing major problems for area businesses.

Green Infrastructure: Curbside Gardens & Sponge Park

In addition to the “gray” infrastructure investments described above, the City is also employing “green” infrastructure to absorb rainwater, reduce wastewater overflows, and minimize street flooding.

In April, the City announced that it would install 90 bioswales, or “curbside gardens,” at locations throughout the Gowanus watershed. Bioswales look like large tree beds, but are specially designed with particular soils, stones, and vegetation to collect and absorb rainwater from streets and sidewalks. (More details here.) Construction is currently underway on 1st Street, near 4th and 5th Avenues, where the sidewalk has been excavated, backfilled with graded stone and engineered soil, and new curbs installed.  You can see if there’s a location coming to your block here.

Also under construction is the Sponge Park, which you may have seen in the New York Times last week. At the end of 2nd Street, this 2,100 square foot park will absorb thousands of gallons of rainwater and the pollutants it washes off city streets, like litter, bird droppings, dog waste, and contaminants produced by cars such as antifreeze, cadmium, oil, and zinc.

All of the remedies described about are included in the Long Term Control Plan for the Gowanus Canal watershed, which was released this summer.


Part 3: The Land

The Gas Plants

In the late-nineteenth and early-twentieth centuries, there were three manufactured gas plants near the Gowanus Canal. Today they are referred to as the Fulton, Citizens, and Metropolitan MGPs. From each plant, a network of pipes brought gas to homes and businesses for lighting, heating, and cooking. Coal tar is one byproduct of gas production from this era that is a major source of contamination in the canal and some land around it today. It is a reddish-brown oily liquid that can move laterally underground, away from the location where it was deposited, making it difficult to contain and remove.

Similar to the construction of the CSO retention tanks, it is important that remediation of the MGP sites be phased with Superfund dredge, so that the coal tar does not recontaminate the canal. The EPA is working together with the State, which oversees MGP remediation, and National Grid (formerly Brooklyn Union Gas) to adhere to the below schedule:

  • Fulton MGP: located near Area 1 (at the north end of the Canal, including Thomas Greene Park and blocks nearby), remediation expected in 2016. Details here.
  • Citizens MGP: located near Area 2 (including “Public Place,” the area between the Canal and Smith Street, between 5th Street and 7th Street), remediation expected in 2018. Details here.
  • Metropolitan MGP including the Lowe’s and former Gowanus Pathmark sites. Details here

A remediation plan was proposed for the Fulton MGP in April 2015, which includes stipulates construction of a wall along the canal to prevent migration coal tar in the short term and excavation of deeper contaminated material in the long-term. The footprint of the former Fulton MGP includes the Douglass & Degraw Pool in Thomas Greene Playground. Coal tar does not present a danger to those who use the park today. However, in order to excavate the deeper contaminated material, the pool will be removed and reconstructed.

Other Brownfields

In addition to the manufacturing gas plant sites, there are many “brownfields” in Gowanus, or properties where contaminants in the land exceed standards put forth by the State. These properties may or may not contribute directly to the pollution in the canal – but must be cleaned up before new development can take place.

The remediation of the land at the new Lightstone development is complete, and cleanups are in the works for many other properties, including 563 Sackett St, 450 Union St, and Bayside Fuel Oil.

In general, the New York State Department of Environmental Conservation (DEC) has oversight of brownfield remediation. The City of New York can add an “E” designation to its zoning maps, which requires additional cleanup oversight (as it did for the Lightstone site, and would likely do for any other sites near the canal that were rezoned to allow for residential use).

Where the EPA has identified that brownfield sites may contribute cause future contamination in the Canal, they provide a strong additional layer of oversight and protection – as they did at the Lightstone site, where they ordered substantial additional soil removal and remediation.

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