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Gowanus Canal Superfund Cleanup Begins: 'You’re Gonna Smell Some Smells'

 The EPA can be seen Tuesday making preparations to dredge the canal's infamous black mayonnaise, a 10-foot high layer of toxic sludge at the waterway's bottom.
The EPA can be seen Tuesday making preparations to dredge the canal's infamous black mayonnaise, a 10-foot high layer of toxic sludge at the waterway's bottom.
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DNAinfo/Amy Langfield

GOWANUS — It's really happening.

Those who live and work along the Gowanus Canal will start to feel, hear, and smell work getting underway as the U.S. Environmental Protection Agency prepares to dredge 20,000 cubic yards of toxic muck from the Superfund site's Fourth Street Basin, officials said Tuesday night. 

"I don’t know if you realize this folks, but this is the real deal," said Christos Tsiamis, the EPA's remediation project manager. "For the first time in well over a century there will be a portion of the canal with a brand new bottom."

The work comes after the EPA kicked off its dredging pilot in the basin earlier this month and cleared the way for equipment to access the toxic sludge known as "black mayonnaise" at the bottom of the canal.

Dredging is set to begin in early December and will take approximately two months.

By May, the Fourth Street Basin will be the first "clean" stretch of the canal.

Starting Tuesday, workers began installing 60-foot tall steel beams along the Fourth Street Basin's banks to support existing bulkheads. The beams will be positioned through a vibration method and then sheered off at the top, concealing the bulkhead supports beneath the surface.

Five sound meters have been placed near the basin — three on the north side, two on the south side — to monitor noise levels and will send officials an alert if there is sound above 80 decibels. If it exceeds 85 decibels the monitor will actually snap a picture to help workers isolate the source.

Sediment that has already been scraped up is being floated down the waterway by barge where it will be mixed with cement to trap toxins and odors, but locals are bound to catch a whiff of some foul smells as the pilot continues.

“You’re gonna smell some smells," said Dave Himmelheber, a senior engineer with Geosyntec Consultants, who the EPA hired to help with the project's design. "We’re making sure they’re not dangerous or toxic to you — they’re just smells.”

The extricated sediment will be used to cover landfills in Pennsylvania and chunks containing too much liquid tar will be sent to facilities in New Jersey that will burn them away. Muck left out overnight will be covered with a tarp or sprayed with foam to soak up the smell, Himmelheber said.

The dredging will be followed by a process known as capping that will lay two feet of sand, clay and other granular materials to prevent contaminants from migrating up into the water. The uppermost section of the barrier will be an "armor layer that provides hydrodynamic stability" to the canal's bottom, noted Himmelheber. 

The process is expected to wrap up in April, according to Tsiamis.

Overall, dredging will remove 11 feet of sediment and capping will replace two feet, said Himmelheber.

Officials aim to use data from the pilot to finalize the cleanup plan for the northern portion of the canal by February 2019. The cleanup for that stretch of the canal will likely be completed in 2022.

The entire EPA cleanup will wrap up around 2027.