Long-Overdue Dredging Of Gowanus Canal Turns Up 'Black Mayonnaise,' Sunken Cars, Evil Stench

Dredging the Gowanus Canal.

The first section of the Gowanus Canal being dredged is adjacent to a public promenade at 363 Bond Street and 365 Bond, a pair of new apartment towers built at the water’s edge.

During the first phase of the cleanup, the EPA will remove approximately 72,400 cubic yards of ‘black mayonnaise’ from the bottom of the canal, in an area extending from the Third Street Bridge up to the head of the canal.

The dredging is taking place in front of the Brooklyn Rapid Transit Company (BRT) central power station, a heavily polluted property that is being remediated and redeveloped as part of Powerhouse Arts. A new tower designed by Herzog & de Meuron is rising here, next to the old powerhouse.

The dredging is immediately adjacent to the esplanade, and just outside the windows of the apartments at 363 Bond Street and 365 Bond. This waterfront area is a popular destination for local families.

The EPA has placed an air monitoring station on the promenade to record any air pollution released by the dredging. The promenade is used by dog walkers and bicyclists, and as a park for children.

A dredging crew removing pilings next to the Carroll Street Bridge, which is immediately adjacent to the public esplanade. The dredgers will remove 10 feet of sediment from the bottom of the canal, which is polluted with industrial chemicals, liquid tar, and heavy metals like mercury and lead.

Workers used a welding torch and chainsaw to cut the pilings in half, before pulling them out from the bottom of the canal. After it is dredged, the bottom of the canal will be capped with layers of sand, concrete and gravel.

Just north of the Carroll Street Bridge, the shoreline is being excavated and new bulkheads are being built, to contain any pollution buried inland from leaking into the canal. Coal tar plumes have been found underground along the canal’s shoreline, going down to a depth of more than 150 feet.

Diners at Pig Beach, a barbecue restaurant on Union Street, sit outdoors next to a polluted excavation site. Dredging crews will also be digging up sediment from the water next to the restaurant, as part of the first phase of the cleanup.

After a barge is filled with dredged materials, it is pushed down the Gowanus Canal, past the Third Street Bridge. The Department of Transportation has stationed crews of bridge workers along the canal, to raise and lower bridges throughout the day.

Barges filled with ‘black mayonnaise’ are moored alongside the Whole Foods Market, in the 4th Street Turning Basin. The waterfront esplanade here is a popular destination for shoppers, families and children.

The barges sometimes sit overnight, or through the weekend, alongside the promenade, before being transferred further down the canal. Air monitors have been installed nearby to record any toxins they might release.

The contents of the smaller barges are transferred to a larger barge, which is moored at the end of Huntington Street, on the west side of the canal. The canal water is drained and treated here, before being pumped back into the canal.

After being drained, the dredged material is transferred to a treatment area in New Jersey, where larger objects like tires and logs are removed. Some of the remaining material will be turned into a “beneficial use product,” like a material to cover landfills.

The dredging process is unearthing toxins that have been buried for more than a century, and the water near the barge transfer site is covered with oil slicks and other debris. According to the EPA, booms have been placed in the water, to stop this pollution from flowing out into the New York Harbor.