Celebrating a key milestone for the Gowanus Canal in Brooklyn, NY

The excavation for the 8-million-gallon (30-million-liter) combined sewer overflow (CSO) tank in the Gowanus neighborhood of Brooklyn was recently completed. This is a key milestone in the New York City Department of Environmental Protection (DEP) project that will intercept and store combined sewage that would otherwise overflow into the Gowanus Canal during rainstorms.

In 2023, the CDM Smith – Mott MacDonald Joint Venture, was engaged to serve as the construction manager by the DEP to coordinate and oversee the construction of the underground tank. As the construction manager, our team is working closely with designers and contractors on-site to deliver the project under an accelerated schedule, while navigating the challenges of working in a dense urban neighborhood with a history of industrial contamination.

“The team has been able to meet the demands of a very challenging and technically complex project head-on through close collaboration with the DEP, their engineer of record, and the contractor,” said Eric Prantil, senior project manager at Mott MacDonald and Resident Engineer on-site. "We took two city blocks and sank them 40 feet deep in record time."

“Much of the credit for achieving this major milestone goes to our dedicated field team lead by Eric Prantil, which required working around the clock to meet a very ambitious schedule,” said CDM Smith’s Construction Manager Brian Farrelly. “The teamwork and collaboration on this project was as good as it gets”.

With the mass excavation completed, the next phase of work will be the construction of the concrete tank structure, including interior permanent works, cast in place concrete, and a roof slab which will cover the entire structure. The concrete work will be performed in parallel with the construction of ancillary influent and outfall structures, which will connect the tank to the existing Gowanus Pump Station and the canal.

The Gowanus Canal, originally a tidal creek, was channelized in the 1800s to support industrial commerce. In 2010, the United States Environmental Protection Agency (US EPA) designated the Gowanus Canal a Superfund site. The US EPA-led remediation of the canal is underway with the dredging of contaminated sediment and capping of the canal bed. The completion of the Gowanus Canal cleanup and CSO tank project provide a cleaner and healthier canal and provide much needed public open space for residents and visitors.