The U.S EPA has recently published a feasibility study, or outline of the remedial options selected for the cleanup of the highly contaminated Gowanus Canal in Brooklyn, New York. This is the latest development in the ongoing debate about how to proceed with the cleanup. The Gowanus Canal was finally added to the Superfund’s National Priority List (NPL) in March 2010, which contains some of the country’s most hazardous waste sites. The newly completed feasibility study evaluates the technologies that could be used to clean up the canal, and will be used to develop a cleanup plan for the Gowanus Canal.
The Gowanus Canal was built to allow access for industrial needs by bulkheading and dredging a tidal creek and wetland that had previously been fished for oysters. After its completion in the 1860s, the canal quickly became one of the nation’s busiest industrial waterways, home to heavy industry including gas works, coal yards, cement makers, soap makers, tanneries, paint and ink factories, machine shops, chemical plants, and oil refineries. It was also the repository of untreated industrial wastes, raw sewage, and surface water runoff for decades, causing it to become one of most polluted waterways in New York’s and the entire United States. Although much of the industrial activity along the canal has stopped, high contaminant levels remain in the sediments. Despite the ongoing pollution problems, some city dwellers currently use the Gowanus Canal for recreational purposes, such as canoeing and diving, while others catch fish for consumption.
Samples collected from the sediments in the Gowanus Canal have shown to be contaminated with a variety of pollutants, including polycyclic aromatic hydrocarbons (PAHs), volatile organic contaminants (VOCs), polychlorinated biphenyls (PCBs), pesticides, and metals. PAH concentrations were found to be as high as 45,000 mg/kg and the contamination was found to extend throughout the entire length of the canal. Many of the detected contaminants are known carcinogens. The contaminated sediments pose an immediate risk to the fishery located just downstream of the canal in Gowanus Bay, as many of the local residents consume the fish that are caught.
The primary objective for the remedial action is to reduce the levels of toxicity of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and metals to acceptable ranges. The options listed in the feasibility study include seven alternatives where the sediment layer at the bottom of the canal will be dredged and capped with a sand and gravel layer, an isolation layer, and an armor layer to protect from potential future contamination. Additionally, several options for treatment and disposal of the sediment are outlined in the feasibility study. Many options include ex situ (or off-site) treatment and disposal, such as at a landfill, which is a very easy practice, but not the most sustainable. One option considers an on-site treatment and beneficial reuse of the sediment for various applications, a “green remediation” technique. The EPA has published the document online, asking the public to submit comments and suggestions pertaining to the cleanup options. The entire 108 page feasibility study can be found here.