After preliminary work that began three years ago, the U.S. Environmental Protection Agency this week issued an administrative order to officially start the cleanup of the Gowanus Canal Superfund site in Brooklyn, N.Y.

The latest $125-million work segment will involve full-scale dredging and capping of the upper third of the 100-ft-wide, 2-mile-long canal and restoration of another area, according to EPA. The entire project is valued at $500 million, ENR reported earlier.

The order comes after a dredging and capping pilot program at the Fourth Street Basin, which started in 2017 and landed the Superfund site on ENR New York's Top Starts list for 2017.

According to Dodge Analytics, the Gowanus Canal's top and middle segments contain 307,000 cu yd of highly contaminated sediment.

Among the Superfund site project team members, Dodge says, are CH2M, now part of Jacobs, and Louis Berger Group, now part of WSP.

National Grid, which is in charge of the cleanup, became liable for the pollution after it acquired the sites of former manufactured gas plants, which discharged waste into the canal along with gas plants, tanneries, paper mills and other businesses formerly located in the site area.

“We’ve come a long way to achieve this significant milestone in cleaning up the Gowanus Canal," said U.S. Representative Nydia M. Velázquez (D), who represents New York City's seventh district.

She added that the Gowanus project is "on an ambitious timeline for cleanup as compared to other Superfund sites throughout the nation."