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Gowanus Canal

Improving Water Quality

DEP is undertaking a number of projects and other activities to improve water quality in the Canal and meet its obligations under a CSO Consent Order. Some of these are already under construction and some require long-term planning.

In 2009, DEP initiated the $160 million Gowanus Facilities Upgrade Project. This project has two main components, modernizing the Flushing Tunnel and reconstructing the Gowanus pump station. The project is scheduled for completion by the spring of 2014.

In addition, DEP has submitted an application to the DEC and the US Army Corps of Engineers to dredge an 825-foot section of the Canal, starting at the head end near Butler Street. This dredging is intended to eliminate the accumulated sediment mounds at this location, reduce associated odors, and provide an improved surface for benthic habitat.

The Gowanus Canal Flushing Tunnel

Historic photo of the tunnel

The original Flushing Tunnel used a seven-foot diameter propeller to pump water from the Canal into Buttermilk Channel. The tunnel operated until the mid-1960s, when service was suspended due to mechanical failure. The tunnel remained out of service for the next three decades.

Between 1994 and 1999, the facility underwent rehabilitation and in April of 1999, the tunnel was reactivated to bring water from Buttermilk Channel into the Canal. The reactivation resulted in dramatic improvements to water quality in the Canal, significantly increasing levels of dissolved oxygen.

However, periodic shutdowns of the Flushing Tunnel were necessary to repair equipment failures resulting from corrosion of the submerged components. The persistence of these failures, along with the lack of redundancy in the Flushing Tunnel system, necessitated a complete upgrade to ensure reliability and improve water quality.

Under the Gowanus Facilities Upgrade Project, DEP is installing three new submersible pumps to replace the original single propeller configuration, and rehabilitating portions of the 1.15 mile tunnel. The new interchangeable pumps will eliminate shutdowns at low tide and will virtually eliminate shutdowns for maintenance. In addition, the tunnel’s flow capacity will increase from 154 million gallons per day (mgd) to 215 mgd. This work is scheduled to be completed in the spring of 2014.

Gowanus Pumping Station Upgrade

Proposed post-upgrade rendering of the Gowanus facilities

DEP is also improving water quality by reducing CSOs into the Canal. To accomplish this, DEP is upgrading the Gowanus Wastewater Pumping Station, which pumps wastewater to the Red Hook Wastewater Treatment Plant. The project will increase the station’s pumping capacity from 20 mgd to 30 mgd. In addition, DEP is constructing a new mile-long force main from the pumping station to the Columbia Street / Red Hook Interceptor Sewer. These improvements will decrease the frequency and intensity of CSO events and the volume of CSO discharged to the Canal by approximately 34% on an annual basis. In addition, DEP will install a screening device at the head end of the Canal to remove floatables and other solid materials that may be discharged during CSO events. This work is scheduled to be completed in September 2014.

For the long-term, the DEP is working on the following two key City-wide water quality initiatives:

Using Green Infrastructure

In March 2012, DEC and DEP agreed to a groundbreaking modification of the CSO Consent Order to include green infrastructure as a substantial component of the City’s CSO control program. Green infrastructure is an alternative approach to improving water quality by capturing stormwater and thereby reducing CSOs. Examples of green infrastructure include permeable pavement, bioswales, which are tree pits with a curb cut to allow absorption of runoff, and green roofs. DEP has prioritized the Gowanus Canal neighborhood for green infrastructure development. DEP plans to spend approximately $11 million over the next few years on green infrastructure projects in the area.

Long Term Control Plan

As part of the 2012 modification to the CSO Consent Order agreement, DEP agreed to develop Long-term Control Plans (LTCPs), or comprehensive evaluations of long term solutions, to reduce CSOs and improve water quality in the City’s waterways. The goal of each LTCP is to identify appropriate CSO controls necessary to achieve waterbody–specific water quality standards, consistent with the Federal CSO Policy and subsequent guidance. The LTCP for the Gowanus Canal is scheduled to be complete by June 2015.

Community Notice

The improvements to the Flushing Tunnel, including the installation of the new wastewater force main, are taking place along a mile long stretch in Brooklyn that runs through several neighborhoods. In order to provide direct communication and coordination with the community along the Flushing Tunnel route, an on-site Project Manager and Community Liaison were enlisted to respond to any questions or concerns relating to the construction. For more information, please contact Shane Ojar, DEP Director of Community Partnerships, at (718) 595-4148 or Marlon King, Gowanus Site Project Manager, at (347) 725-4388 x209

Roadway work on Degraw Street near Columbia Street required a full closure of Degraw from Columbia Street to Tiffany Place. The roadway was reopened in March 2013 after completion of the construction of the Tunnel Exit Chamber. At the main Gowanus Pump Station site, one-lane road closure has been in place on Butler Street between Bond and Nevins Streets for construction of the wastewater pumping station and service buildings. This closure will be removed when the roadway restoration work begins in late 2013.

Gowanus Sponge Park™

Proposed rendering of the Gowanus Sponge Park

The City is also moving forward on an innovative park to help improve water quality in the Canal. The new Gowanus Sponge Park™ will occupy 1,800 square feet where 2nd Street meets the west side of the Canal. This prototype green infrastructure park will feature a surface that will capture and retain stormwater before it reaches the Canal.

Construction of the park will involve excavation of the roadway to a depth of four feet and installation of a modular system of concrete cells filled with engineered soil to store and filter stormwater runoff. Native plants will absorb, filter and evapotraspirate water through their roots and leaves, as well as act to phyto-remediate toxins from the runoff. A ten foot wide walkway over an overflow sand filter area will provide public access to the Canal. Construction is expected to begin in 2014, with the park scheduled to open to the public in the the summer of 2015.

The Gowanus Sponge Park™ was announced at a press conference held at the site on July 31, 2013. You can read more about it here.

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