4,000 Gallons of Coal Tar Already Removed From Gowanus Canal Site

Hazardous coal tar permeates six acres of heavily polluted city-owned land beside the Gowanus Canal—and the state's plan to remove and contain the toxic sludge has some residents worried.

At a meeting of the Gowanus Canal Community Advisory Group on Tuesday night, Gardiner Cross of the state Department of Environmental Conservation said the plan to remove the tar, which is in the ground all along the Gowanus Canal, is already underway at the Public Place site between Huntington and 5th Street. It will also start the process at two other locations in the next year.

Coal tar is a by-product of manufactured gas, and the three sites to be excavated of the gooey black stuff were all once manufactured gas plants.

"There's an awful lot of this gooey liquid," said Cross. "Public Place is leaky, it drips and draps into the canal."

While the federal EPA is responsible under the Superfund designation to clean-up the canal itself, it is the responsibility of the state DEC and the property owners to make sure the land beside the canal is cleaned up.

According to Cross, the best way to clean up coal tar is to excavate—first dig out the land and then take it to a hazardous waste dumping site. However, along the Gowanus, where the land is at water level and is wet and sandy, excavating only works so well. Coal tar is mobile, and sinks in water, said Cross.

In other words, it finds its way into the soil and is hard to remove.

"There comes a point when you say, 'Okay, we're going to stop digging here and do something else,'" said Cross.

Other options include isolating the tar, by installing steel walls.

The DEC has found that tar penetrates more than 100 feet into the ground in some places, and to get rid of it, has already installed 13 permanent wells, which pump the tar out into a drum, which then gets carted off to a waste site. They are now testing ways to install steel sheeting walls along the canal, to make sure the tar doesn't escape into the water, said Cross.

Of course, there are issues with exactly how to keep the tar from entering the waterway. Steel sheeting comes in sections, and the joints have gaps. And the tar is so strong it will find a way to get through the tiniest spaces, said Cross. The sheets will be installed 50 feet deep in some places.

Residents wondered about tar seeping into groundwater, which could potentially run off onto their properties or into the canal. They also expressed concern with how thorough the plan to remove the tar really is.

"We are concerned about the people who will be living there," said Steven Miller, a resident and member of the CAG.

Indeed, the Public Place site is where the city envisions "Gowanus Green," a 774-unit housing development with 70 percent affordable housing, as well as open space and public land.

Cross admitted the coal tar was a huge problem.

"If you're ever going to have a healthy canal, you're going to have to get this stuff out of there," he said.