Gowanus

Believe it or not, the Gowanus Canal cleanup won’t start until 2020

July 24, 2018 By Scott Enman Brooklyn Daily Eagle
EPA began the last phase of its dredging and capping pilot project on Monday, the third and final study before the actual cleanup of the Gowanus Canal commences. Eagle photos by Paul Frangipane

It’s the final countdown.

The Environmental Protection Agency began the last phase of its dredging and capping pilot project on Monday, the third and final study before the actual cleanup of the Gowanus Canal commences.

While some may have assumed the cleanup was already ongoing, EPA was only performing a series of tests to determine the most effective methods for eventually cleaning the entire canal.

The 1.8-mile toxic waterway was declared a federal Superfund site nearly a decade ago in 2010, but the remediation process isn’t slated to begin until mid- to late-2020.

“Before we do the cleanup, we do the design,” Christos Tsiamis, project manager of the Gowanus cleanup, told the Brooklyn Eagle. “As part of the design, we have some actual trials in the canal, pilot studies of the techniques that we’re going to use in the main body of the canal.”

A crane operator floating on a barge on the Gowanus Canal lifts the machine’s arm out of the water after dropping sand to the bottom of the canal.

Tsiamis said the tests also determine which types of equipment are best suited for the estimated $506 million cleanup.

The first trial, to stabilize sediment at the bottom of the canal, occurred in 2015 at the Seventh Street Basin. EPA successfully injected cement into tar to prevent it from moving upwards.

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The second trial, completed in 2016, involved debris removal at the Fourth Street Basin near Whole Foods. Notable objects taken out of the water included two sunken boats, a tree, tires, shopping carts, a bocce ball and an anchor from as early as the mid-19th century — but no corpses.

EPA started the final study of dredging and capping in October. The agency removed 17,000 cubic yards of contaminated material from the bottom of the Fourth Street Basin, including the revolting black mayonnaise.

The agency is currently installing 2.5 feet of capping, five separate layers at the bottom of the canal, which will act as a filtration system and suppress toxins.

“The different materials can absorb any contamination that is in the water that comes from the bottom of the canal,” Tsiamis said. “We isolate anything that comes upwards so we can maintain the water above the bottom in a clean state.”

 

The first layer, made of sand, is called leveling. The second layer is a mixture of sand and organic clay, which can absorb contaminated material. The third layer is made of sand and activated carbon. The fourth layer is another coating of sand.

The fifth tier is called the armor layer, a honeycomb-like level of cement with holes filled with gravel that allows aquatic life to flourish and for filtered water to pass through. The entire capping process is expected to be completed in mid-September.

“We’re going to take the lessons learned [during the pilot studies] and complete the design, which will be done by April 2019,” Tsiamis said.

He added, “The area that we completed in this pilot, that’s its final cleanup. We’re finished. So in 2020 we expect to start the dredging at the top of the canal and then it should go on a continuous basis.”

The entire canal is projected to be cleaned entirely by 2027 at the earliest.

Follow reporter Scott Enman on Twitter.

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