From: David A Gabel, ENN
Published December 28, 2012 09:40 AM

EPA Proposes Ambitious Plan to Clean the Gowanus Canal

The Gowanus is one of the United States' most polluted waterways, bisecting Brooklyn and emptying into Upper New York Harbor. Many years ago, it was a major industrial transportation route, servicing manufactured gas plants, paper mills, tanneries, and chemical plants. At the time stormwater runoff and discharges from these facilities were constantly being absorbed into the canal. The Gowanus was added to the EPA superfund list of sites, and numerous potentially responsible parties have been identified including National Grid and the City of New York. After thorough environmental investigation, EPA has finally proposed a plan to conduct the cleanup, which will include the removal of contaminated sediment, capping dredged areas, and preventing further land-based contaminated outflows. The expected cost of the project is between $467 and $504 million. The EPA will be taking public comments on the plan from now until March 28, 2013.

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Many areas of Brooklyn are undergoing a renaissance, and the area around Gowanus is no exception. The historic neighborhoods of Carroll Gardens, Park Slope, Red Hook, and Gowanus which are all in the vicinity of the Gowanus Canal hold thriving and creative communities. The revitalization of these neighborhoods would likely be further bolstered by a cleaner canal.

There are more than a dozen contaminants in the canal sediment, including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and heavy metals such as mercury, lead, and copper. Many of the contaminants found are suspected and known carcinogens. As a result, nobody ever swims in the canal, many hold their breath, and fishing is prohibited, however consuming fish from the canal still continues despite the warnings.

The cleanup plan is divided into three parts for three segments of the canal: upper, middle, and lower. The upper and middle portions which run from the top of the canal to just south of Hamilton Avenue Bridge are the most heavily contaminated.

For these two sections, EPA proposes to dredge over 300,000 cubic yards of highly contaminated sediment. This is a very difficult task because the dredging action can stir up the contamination which has settled on the bottom, suspending it in the water where it can move to other areas. Containment will have to be built around each small area that is dredged.

Areas of liquid coal tar in the sediment will be stabilized by mixing it with concrete, and then capping with clay, followed by an "isolation" layer of sand gravel, and finally an "armor" layer of heavier gravel and stone to prevent erosion. Finally, a clean sand layer will be placed on top to restore the benthic habitat of the canal bottom.

The lower section of the canal, from south of Hamilton Avenue Bridge to the mouth of the canal, is proposed to have 281,000 cubic yards of contaminated sediment removed. The areas would then be capped with the "armor" layer and clean sand to restore habitat.

Other cleanup aspects will be removing contaminated material placed in the 1st Street Turning Basin decades ago, and a plan for managing the sediment after dredging. Two methods will be transporting to an off-site permitted disposal facility, and transporting to a location where the sediment can be treated for possible beneficial reuse.

To prevent future contamination, EPA proposes installing new control technologies for two major sewer outflows in the upper portion of the canal. The controls would be able to reduce the total volume of discharges by 58% to 74%.

EPA is holding public meetings where they will take comments and questions on the following dates:

- January 23, 2013, 7:00 pm, - Public School 58 (the Carroll School)

- January 24, 2013, 7:00 pm, - Joseph Miccio Community Center, 110 West 9th Street

For more information and a link to the proposed plan, click here.

Image credit: A. Jesse Jiryu Davis

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