Providing a cleaner and healthier canal in Gowanus, Brooklyn

Clean up and remediation of the Gowanus Canal

The Gowanus Canal, a 1.5-mile-long (2.4 km) waterway built in the 1800s to support industrial commerce, has a legacy of industrial pollution and contamination from combined sewer overflow (CSO) outfalls. In 2010, the US Environmental Protection Agency (USEPA) announced plans, along with local authorities, to clean the canal and remediate the area.

Employing technical excellence to construct combined sewage overflow storage tanks

In 2023, the New York City Department of Environmental Protection (NYCDEP) engaged the CDM Smith – Mott MacDonald Joint Venture to serve as the construction manager and oversee the construction of an 8-million-gallon (30,283-kiloliter) CSO storage tank designed to prevent sewer overflow from entering the Gowanus Canal during rainstorms.

As the construction manager, our team worked closely with the client, contractors, and designers to develop an accelerated schedule to deliver the mass excavation of the CSO tank six months earlier than originally anticipated.

A variety of geo-structural and civil engineering techniques were utilized to overcome the challenges of working in a highly urbanized area, with soils contaminated by former industrial activities and a shallow groundwater table. The team built slurry walls extending 160 feet (50 meters) deep in combination with permeation grouting to form the groundwater cutoff around the perimeter of the tank. In addition, several other support of excavation (SOE) systems and ground modification techniques were deployed, including soldier pile tremie concrete walls, jet grouting, braced support of excavation systems, dewatering, micropiles, soldier piles, and sheet piles.

Upon completion of the mass excavation of the tank, the interior of the structure, including holding cells, sedimentation tanks, and screening elements, will be constructed from cast-in-place (CIP) concrete.

A green space and cleaner water for the Gowanus community 

The completion of the Gowanus Canal cleanup will transform Gowanus into a revitalized waterfront with open space and improved water quality for residents and visitors.