The Environmental Protection Agency (EPA) has rejected a city proposal that would have swapped two long-planned tanks with a massive tunnel to divert raw sewage from the Gowanus Canal, capping a months-long debate over how the city should ensure the waterway remains clean after its costly federal remediation.
As part of the Superfund effort, the city’s Department of Environmental Protection (DEP) is required, at its expense, to curb the amount of untreated waste that flows into the canal. Originally, DEP sought to do this with two multimillion-gallon underground tanks, but recently asked to switch to a tunnel that would have captured four million more gallons of fetid run-off, according to DEP.
After months of review, the EPA rejected the city’s proposal on September 20, pointing to “significant concern” over additional costs and project timeline impacts, among other things, according to Peter Lopez, the agency’s New York regional administrator.
“The result of this review has led to our determination that the technical record does not support changing the current remedy approach from CSO [Combined Sewer Overflow] retention tanks to a CSO tunnel,” Lopez wrote in a recent letter to Vincent Sapienza, the commissioner of DEP.
DEP spokesperson Ted Timbers blasted the decision, declaring that “President Trump’s EPA is at it again: ignoring science and facts when making significant decisions that impact New Yorkers’ lives.” Timbers argues that the tunnel would have increased the amount of sewage captured during heavy rains by 33 percent over the pair of tanks, “all with negligible cost and timeline impacts.”
The first of the tanks—an eight million gallon basin—would be operational by November 2029, while the second, smaller tank would be up and running by July 2030 for a combined cost of $1.193 billion. Comparatively, DEP expected the tunnel’s completion by December 2030 for $1.250 billion. The EPA says the project could actually cost at least $50 million more than the tanks and cause a two-year delay that would stall the dredging of the toxic “black mayonnaise” at the bottom of the canal.
“We are extremely disappointed that the EPA is not allowing the city to build a better, less disruptive project for the community,” says Timbers.
The main draw of the tunnel alternative, DEP says, is that it gives the city the option to potentially lengthen that tunnel for greater capacity down the road, unlike the tanks. This is an especially relevant perk now that Gowanus is in the midst of a city-led rezoning poised to transform the neighborhood with a surge of residential development, and therefore a greater burden on the neighborhood’s sewer infrastructure.
“Once you build those two tanks they’re basically a dead-end-asset. It’s going to be very tough to build any additional capacity beyond the eight and four million gallons, but with the tunnel you can add on to that,” Kevin Clarke, a portfolio manager with DEP’s Bureau of Engineering Design & Construction told the Gowanus Community Advisory Group in a January presentation on the tunnel.
In his letter, Lopez suggested in lieu of a tunnel, that DEP could expand the size of its tanks if the city thinks that’s necessary “in relation to its rezoning proposal,” he said in his letter. DEP would not say if it’s exploring this option.
The Department of City Planning has maintained that it does not expect new development brought on by the rezoning to inundate the newly cleaned canal with fetid runoff, and that it is working with DEP to develop mitigations, including a new facility that could intercept sewage before it reaches the canal. Those talks are ongoing.
But Christos Tsiamis, the EPA’s remedial project manager for the Gowanus Canal cleanup, says the federal agency would step in to develop a case-by-case plan for new canal-adjacent buildings, and that developers would likely need to treat their own sewage to ensure a clean canal isn’t defiled.
“The developers will have to assume responsibility for not overloading the system,” said Tsiamis. “We stand by that.”