By Raanan Geberer
Brooklyn Daily Eagle
The Gowanus Canal Flushing Tunnel, which “flushes” fresh water from Buttermilk Channel into the heavily polluted canal, is going back into service this week for the first time since 2010, according to Department of Environmental Protection Commissioner Carter Strickland.
The tunnel, which often operated at only partial capacity, was under repair for three years. It begins at the channel, and for most of its route carries water under DeGraw Street. Near the canal, it turns one block north onto Hoyt Street and then onto Douglass Street.
The rehabilitation work included draining the 1.2-mile-long, 12-foot diameter tunnel and repairing its brick-lined interior. In the wake of Hurricane Sandy, resiliency measures such as raising the control room floor and flood-proofing the service building were also added.
Early next year, it is expected that two additional turbine pumps will be activated, allowing for the injection of as much as 252 million gallons of fresher water into the canal each day, or roughly 30 percent more than it could before the upgrade, according to the city’s Department of Environmental Protection (DEP).
The three pumps will provide redundancy and make maintenance easier – until now, there has been only one operable pump.
One of the reasons for its breakdowns was that when the tunnel was last rebuilt in 1999, it was built to the original 1911 specifications, making it difficult to get parts. In addition, debris sometimes got caught in its blades.
When the flushing tunnel was taken off line in 2010, a temporary oxygen transfer system was installed alongside the canal to help maintain a minimum level of oxygen, according to DEP. Removal of this temporary system could begin as early as January.
“A clean and healthy Gowanus Canal will help ensure that the communities surrounding the Canal are safer, more sustainable, and aesthetically pleasing,” said City Councilmember Stephen Levin (D-Downtown/Heights).
“The reactivation of the Gowanus Canal flushing tunnel is yet another example that the clean-up of the canal is well underway,” added NYS Assemblywoman Joan Millman. “I thank DEP for both repairing the flushing tunnel as well as increasing its capacity.”
“It [the tunnel] has been a challenging piece of infrastructure,” said Hans Hesselein, executive director of the Gowanus Canal Conservancy. “It will make the canal much for supportive of aquatic life.” In addition, he said, it will reduce the canal’s odor, often a source of complaint by local residents.
The Flushing Tunnel was built between 1905 and 1911 at a cost of nearly $1 million, and was opened with great fanfare. Even then, the Gowanus Canal, built as an industrial waterway, was considered one of the most polulted bodies of water in New York City. The tunnel helped – somewhat.
Unfortunately, it was shut down in 1960. Rumor has it that barge operators didn’t want it repaired because they preferred a stagnant body of water with no movement.
After the tunnel reopened in 1999, the quality of the water in the canal improved noticeably, although no one would mistake the Gowanus for a pristine mountain spring. Eels, sea robins, crabs, flounder and other aquatic life returned to the canal, as well as birds.
The Gowanus Dredgers Canoe Club sponsored paddling trips on the canal – something that would have been unheard of in the 1940s or ‘50s.
Part of what makes the Gowanus so polluted is the fact that in New York City, storm runoff water and sewer water share the same pipes. Although this isn’t usually a problem, during rainstorms the amount of water overwhelms the system and sewage floods the canal.
As part of an effort to improve this problem, DEP will install separate storm sewer pipes, or high-level storm sewers, along Third Avenue in Park Slope. Once completed, this project will keep millions of gallons of stormwater out of the combined sewer system, help to mitigate chronic flooding during heavy rainstorms, and reduce sewer overflows into the canal.
The dredging of the canal under the federal Environmental Protection Agency’s Superfund plan is a separate project.