As state police patrolled outside emptied homes, workers in masks and protective clothing began cleaning up Michigan's worst toxic waste dump.

"We're on schedule," said Warren Hutchinson of the state Department of Natural Resources' Environmental Enforcement Division. "We want truckloads of waste out of here."

The workers donned air-monitoring devices--used to detect hazardous fumes--as they moved in to excavate contaminated sludge from a lagoon.

The cleanup began after 54 families were moved from the flat farmland west of Flint to protect them from any toxic fumes.

The site, near the Berlin & Farro Liquid Incineration Inc. property, is No. 16 on the national "Superfund" list of hazardous dumps most in need of cleanup. It is laced with C-56, a toxic pesticide component that gives off dangerous emissions at temperatures above 50 degrees.

The lagoon also is suspected of holding barrels of hydrochloric acid and cyanide, which could form deadly hydrogen cyanide gas if mixed.

Eight of 20 private wells tested were also contaminated, said David Wade, a toxicologist with the state Public Health Department. The wells showed levels of a compound, tentatively identified as isophorone, ranging from one to 10 parts per billion, he said. The effect of isophorone, which is used in paints and varnishes, on humans is not known.