GOWANUS — A bridge over the Gowanus Canal could be fixed in more ways than one.
The Department of Transportation is floating a plan to replace the aging Union Street bridge with one that would block most marine traffic from the northern end of the canal, which could affect the waterway's cleanup, DOT officials told Community Board 6 members Thursday night.
DOT officials presented two options for replacing the 111-year-old Union Street crossing: a movable bridge similar to the current one, or a bridge that wouldn't move at all.
The bridge replacement project is in the "truly conceptional" stage now, said DOT's bridge division chief staff manager Joannene Kidder. The earliest construction could begin would by the second half of 2018, though 2019 is more likely.
DOT wants to start the long-planned bridge replacement as soon as possible because the Union Street span was severely damaged by Superstorm Sandy and has been operating with temporary equipment since.
The Union Street bridge, known in DOT parlance as a "double leaf Scherzer rolling lift bascule," is the northernmost of the five bridges on the Gowanus Canal, all of which are required by federal law to move so boats and barges can pass through.
Businesses along the canal once used the waterway to transport products such as heating oil. There's still commercial marine traffic at the canal's southern end for scrap metal recyclers and cement plants, but no businesses use the Union Street bridge anymore, Kidder said.
Opening the bridge requires two hours notice, and there were a "very nominal" number of requests last year, Kidder said.
New federal flood zone regulations require bridges on the canal to be elevated, which puts "constraints" on DOT's options for replacing the Union Street bridge, said DOT's director of movable bridges Rahul Shah.
Alternatives include movable bridges similar to New Jersey's South Front Street bridge, or the Minnesota Slip bridge in Duluth, Minn. A movable bridge would last about 75 years and would cost about two to three times as much to build as a fixed bridge, Shah said.
The fixed bridge option would create several unique challenges.
Only boats shorter than 7.5 feet would fit underneath, which would mean no larger vessels, including the barges that will dredge toxic sludge out of the canal as part of the U.S. Environmental Protection Agency's Superfund cleanup.
If DOT pursued the fixed bridge option, the city would have to cover the difference in cost between having the dredged sludge trucked out of the neighborhood instead of ferried out on barges, Kidder said.
A Carroll Gardens resident at the Community Board 6 meeting asked if DOT could wait until after the Superfund dredging is complete to replace the bridge, but Kidder said that's not possible. There's no set schedule for the dredging, which EPA said recently would start in 2019, and the city could be forced to wait to replace the rickety bridge at least five or six years, Kidder said.
Construction of the fixed bridge would also mean that property owners along the canal would permanently "lose the opportunity for waterfront access," Kidder said, meaning that they would no longer be able to build docks, piers or boat lifts on their property. The city would have to compensate those property owners for the loss in value to their land, Kidder said.
A fixed bridge would also require a change in the federal regulations that spell out how drawbridges operate on the canal.
Any new bridge on the canal, either movable or fixed, will also require a permit from the U.S Coast Guard. That process could be derailed if even a single member of the public raises concerns about the loss of access for watercraft, Kidder said.
"Mariner rights trump everything," Kidder said.
DOT officials said they didn't need a vote of approval from CB6, just feedback. Board members took an informal poll and most said they preferred the fixed bridge option.
Board member Matt Silverman said the city shouldn't be too hasty in its decision, given the rapid changes happening in Gowanus.
"Gowanus is in a state of flux,” Silverman said. "It's going to have, hopefully, a clean canal. My concern is that a fixed bridge limits its uses. Maybe people are going to bring tour boats up the Gowanus in the future, who knows?"