FORT EDWARD -- Hudson River dredging looks ready to launch, finally.

Workers hired by General Electric Co. are finishing a canal-side wharf for barges and a hangar-sized building to squeeze dry polluted river mud. A rail yard is being built with nearly seven miles of track for shipping out the waste.

After three decades of plans, lawsuits, negotiations, delays and demonstrations, a rural site a few miles from the upper Hudson is being prepared to treat tons of PCB-contaminated river mud beginning next spring -- Phase 1 of a six-year operation that will ultimately scrape away 490 acres of river bottom.

"Nothing like this has ever been attempted before," GE spokesman Mark Behan said over the rumble of construction at the sprawling treatment site being built near the river. "The project is unique in its scope and its size."

GE plants in Fort Edward and Hudson Falls dumped wastewater containing more than a million pounds of PCBs into the river before they were banned in 1977. The gooey compounds once used as coolants in electrical equipment are a suspected carcinogen, and the narrow run of the upper Hudson is considered so polluted that the fish are deemed unsafe to eat.

New York first took steps to clean up the mess in the mid '70s -- one report then said GE might have to spend thousands of dollars. But local opposition, legal fights, studies and bureaucratic wrangling have had the effect of dragging the case on like a raft ride on a long, lazy river.

A 200-mile stretch of river down to New York City was listed as a Superfund site in 1984. GE spent years arguing that dredging would be disruptive and scientifically unsound.

Dredging was a particular sore point with former GE head Jack Welch, who snapped at a pro-dredging nun at a 1998 shareholders' meeting, "You owe it to God to be on the side of truth here."

GE dropped public opposition after the Environmental Protection Agency signed a dredging order in 2002. Dredging could have started in 2005, but legal issues and negotiations pushed back the start date several times.

During the delays, officials picked a 110-acre dredge treatment site along the Champlain Canal, a couple of miles from where the canal connects with the Hudson. Shovels hit the ground here in April 2007 and the "dewatering" site is taking shape.

Behan said the site employs 150 people, making it one of the larger construction projects in upstate New York. Before a single scoop is taken out of the river, the company has already spent $395 million.

Barring 11th-hour glitches, this site will run around the clock next summer, six days a week. It will take sediment scooped up from "hot spots" along a six-mile stretch of river south of Fort Edward, where up to eight dredges will work simultaneously. After being barged to the dewatering site, the sludge will be pressed dry and shipped by train to a burial site in western Texas. The water will be treated.

Neither the EPA nor GE will provide a cost estimate to complete the project.

The scope of the looming project -- more than 200 workers will be involved -- long ago raised fears among locals that their little river towns will be ruined by the incessant rumble of trucks and dredges.

EPA spokeswoman Kristen Skopeck said they are trying hard to minimize trauma. Trucks will detour around Fort Edward, the "clamshell" dredges will leak as little as possible and the operation will be quieter than a lawn mower to people on shore.