With development pushing in from all sides, the cleanup of the 1.8-mile-long Gowanus Canal Superfund site in Brooklyn could again transform a lost marsh and longtime industrial wasteland into the borough’s next waterfront destination. In a report released in late December, the Environmental Protection Agency (EPA), in collaboration with the
New York State Department of Environmental Conservation (NYSDEC), outlined a dual approach to dredge and cap the canal bottom and improve the city’s combined sewer overflow (CSO) problem that dumps raw sewage and other contaminants into the canal during heavy rainfall.
Declared a Superfund site in 2010, the Gowanus Canal will require a cleanup cost of between $467 million and $504 million that will be paid for by New York City and a group of companies liable for past pollution, including National Grid, ConEd, and Verizon, among others.
To remove existing contaminants deposited by 150 years of industrial use from factories, tanneries, and refineries, ten feet of sediment from two heavily contaminated portions of the canal will be removed and capped with a mix of concrete, clay, and sand. A less-contaminated segment will also be dredged and capped with sand. According to the EPA report, no major dredging effort has been undertaken along the canal in the past 30 years. The mix of PCB- and heavy metal-laden sediment will be cleaned and reused, either onsite or at a remote landfill.
After identifying carcinogenic compounds in the sewage dumped into the canal from the city's CSO problems, the EPA expanded the scope of the cleanup to mandate CSO reductions by 58 to 74 percent. “We realized that a lot of the pollution [including carcinogenic polycyclic aromatic hydrocarbons, or PAHs, which result from the burning of fuel] was coming from the CSO,” said New York regional EPA spokesperson John Martin. “We want to make sure the canal doesn’t get recontaminated after dredging is complete.” He said both measures are necessary to ensure the long-term health of the waterway.
Two underground retention basins costing $78 million are proposed at two of the worst CSO sites, to store sewage until nearby water treatment facilities can handle it. Smaller-scale improvements, including green storm-water management, to capture and hold rainwater on surrounding streets, and an environmental restoration project, the Gowanus Canal Sponge Park, designed by Brooklyn-based dlandstudio and funded by city and federal grants, will also help reduce storm-water discharges.
The public is invited to comment online or at two public meetings on January 23 and 24. Martin said a final plan will be drafted by the end of 2013, and the actual cleanup could be completed as soon as 2020, when hundreds of new residences are slated to open up along a canal-side esplanade.