Demolition began Wednesday at the former Cornell-Dubilier Electronics plant, a big step in the federal government's efforts to clean up the contaminated site.

The tract is a Superfund site that ranks among the worst toxic waste sites in the nation. Earlier this month, U.S. Sens. Frank R. Lautenberg, D-N.J., and Barbara Boxer, D-Calif., held a news conference there to criticize the Bush Administration for moving too slowly to clean up toxic waste.

The federal Environmental Protection Agency says plenty of work remains at the former plant.

Electronic components were built there between 1936 and 1962, and the buildings have been found to have elevated levels of dangerous chemicals, including PCBs and lead.

The demolition is expected to last until the summer of 2008.

The demolition did not get under way until many of the businesses in the industrial park on the site had been moved.

"This multiphase cleanup will help the community turn this problem property back into a local asset," said Alan J. Steinberg, the regional administrator for the EPA.