Millions to billions: A price breakdown of the Gowanus Canal’s costly sewage tanks

March 25, 2019 Scott Enman

EPA claims the city's design decisions and choice to acquire property through eminent domain has increased the cost of two retention tanks, while the city claims the EPA's initial estimate was extremely conservative. Eagle file photo by Rob Abruzzese

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The price of two sewage retention tanks built for the Gowanus Canal has ballooned from a projected $78 million to $1.2 billion — more than 15 times the initial figure and more than double the estimated cost of the Superfund cleanup in its entirety.

The federal Environmental Protection Agency claims this steep price tag is a result of the city’s design of the tanks — which differs from the one recommended by EPA — and its choice to build the tanks on private land acquired through eminent domain.

“[The cleanup] includes controls to reduce [combined sewer overflow] discharges and other land-based sources of pollution from compromising the cleanup,” EPA Public Information Officer Elias Rodriguez told the Brooklyn Eagle. “The total cost of the cleanup was estimated in 2013 at $506 million.

“The city’s approach to siting and designing the CSO tanks, including acquiring private property, has increased that portion of the cleanup.”

The city, however, said EPA’s estimate on the cost of the remediation was extremely conservative and didn’t take into account preserving the Gowanus Station Building, a historic structure that activists fought to save from demolition.

“While the initial federal budget estimate was certainly low, and the preservation of 234 Butler St. will certainly add to the cost, achieving the best cleanup of the canal remains the shared goal,” Ted Timbers, communications director of the New York City Department of Environmental Protection, told the Eagle.

DEP, which was named a potentially responsible party for the canal’s pollution, is tasked with covering the cost of the CSO tanks. (The city and National Grid are on the hook for paying for the majority of the cleanup, with more than 25 smaller private parties also contributing.)

The eight-million gallon and four-million gallon tanks, estimated at $77.7 million in the EPA’s record of decision, are one part of the plan to clean the waterway, which also includes dredging contaminated deposit that has accumulated due to industrial and sewer discharges. The chambers will retain sewage and stormwater that currently release directly into the canal through outfalls.

The price of two CSO tanks is projected to cost $1.2 billion, more than double the estimated cost of the entire Gowanus Canal cleanup. Eagle file photo by Rob Abruzzese

The breakdown

The Eagle requested detailed estimates for the two tanks and an explanation as to how the price could be so vastly different from the one projected by the federal EPA. Below is the city DEP’s price breakdown, according to Timbers, who said the numbers “will certainly change moving forward as some of the items are to be determined.”

Professional Services (engineering, construction management): $187 million

Head-end property acquisition: TBD
Head-end CSO Facility Construction: $580 million

Mid-Canal property acquisition: TBD
Mid-Canal CSO Facility Construction: $300 million

Even though the two property acquisitions are yet to be determined, the DEP gave a presentation at the Gowanus Canal Community Advisory Group on Jan. 22 that estimated the land acquisitions would cost about $190 million. If one adds that number into the above figures, the new total comes out to $1.257 billion.

How did the tanks get so expensive?

The city’s preference to install at least one of the tanks on private land acquired by eminent domain at 234 Butler St. and 242 Nevins St. — rather than on city-owned property — adds significant costs. (A third piece of land will likely need to be seized for staging during construction.)

EPA recommended the larger tank be built underneath the Double D Pool in Thomas Greene Park, a city-owned property that already needs to be remediated.

(The mid-canal four-million gallon tank will be placed on a city-owned “Salt Lot,” but DEP has suggested that it may need to acquire additional land next to it for the tank’s support facilities, which will add even more expenses.)

Another disparity in cost is the differences in tank design between the federal and city agencies.

EPA’s concept included a one-chamber eight-million gallon tank that would collect waste and be emptied into a treatment plant once a storm passed. EPA’s estimate did not include a headhouse because it was assumed that, other than odor control and pump housing, all other treatment functions would be performed at a treatment plant where overflow sewage is treated.

DEP decided instead to design a multi-chamber tank with several engineering controls and features that provide different functions for the tank than the one envisioned by EPA.

The costs of the tanks will likely increase based on changes to the neighborhood as well. The city said five million gallon and two million gallon tanks would initially be sufficient, but EPA disputed that amount, saying it preferred an eight million and four million gallon tank — both of which could be increased as Gowanus develops and is rezoned.

“While the sizes of the tanks will be determined during the remedial design, they are expected to … accommodate projected additional loads to the combined sewer system that result from current and future residential development,” the record of decision said.

The projected cost provided by the city for the larger tank has not changed in at least two years, even though the design of it has advanced to near completion. EPA requested a detailed price estimate for it, but the city hasn’t provided it yet.

EPA identified the tanks as the organization’s preferred technique to capture sewage overflows, but DEP has also floated a half-mile tunnel as another option. EPA will ultimately decide which idea to move forward with.

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