North Carolina officials prepared yesterday to begin cleaning a mass of industrial chemicals, including the potent toxin PCB, apparently spilled deliberately along 250 miles of rurals highways.

The removal operation is expected to cost the state government $2.5 million and to involve the excavation of 52,000 tons of soil. The contaminated materials will then be buried in lime landfills meant to separate them from the environment for all time.

Whoever dumped the hazardous chemicals - they are being called "environmental vandals" here - has not been caught or identified. State officials suspect that the spill - actually a series of dumpings - was done by someone seeking to avoid the expense of disposing of the PCBs according to new federeal regulations.

While there have have other previous PCB spills in the United States, the North Carolina spill is unprecedented for its large geographical area.

"Nobody thought anybody would do this dastardly act," says Gov. James B. Hunt Jr. "Few things have happened that have made our people as angry."

PCBs (polychlorinated byphenyls) have been used by industry for more than 30 years, particularly as insulation in electrical transformers. PCBs are a suspected carcinogen, having been found to cause liver cancer in laboratory animals.

State health service offices are passing out leaflets to residents along the routes of the spills, saying that there is no immediate danger to humans. However, PCBs make their way into the food chain and do not break down significantly overtime.

Some residents have reported cases of nausea and eye irritation. Health officials said these are temporary problems caused by other chemicals in the oily mixtures containing PCBs.

The spills occurred in farming regions. A trace of PCBs has already been found in soybean fields. Tobacco farms and dairy herds are also in the area. Dairy farmers are being warned to keep grazing cows away from contaminated grass.

A spill was first found on Aug. 2, subsequent spills were found over several days. Altogether the chemical spills are in 4-mile to 30-mile stretches of highway in 15 counties.

The chemicals were spilled in a narrow brown ribbon along the roadside of several highways encircling Raleigh. Apparently, said officials, one or more tank trucks drove slowly at night down these highways spewing the noxious chemicals as they went.

The first step of the cleanup operation entails covering the spills with a layer of charcoal, which binds and deactivates PCBs and prevents them from seeping further into the soil. Emulsified asphalt will be poured on the contaminated strips along the highways. Finally the entire mixture, including dirt three inches below the surface, will be scooped up with motor graders and vacuuming equipment.

Several sites within North Carolina have been designated as potential places for disposal of the PCB-tainted material. Underground burial is required in vaults lined with clay or a [WORD ILLEIBLE] material. Soil with especially heavy concentrations of PCBs must be shipped to a federally approved disposal operation in Livingston, Ala.

The cleanup operation is being handled under the supervision of the U.S. Environmental Protection Agency, which is also taking aerial photographs with infrared cameras in a search for possible further contamination.

Federal regulations that went into effect in April call for high-temperature incineration of PCBs as a mean of disposal. However, no permits have yet been approved for incineration plants.

Gov. Hunt said he could not give a timetable for the cleanup operation, but he indicated that it would take more than two weeks.

State law enforcement officials have begun an intensive investigation to apprehend those responsible for the spills.

The Highway Patrol has been ordered to increase night details to prevent further dumping. The governor has offered $5,000 reward for information leading to the arrest and conviction of those responsible. Federal and state laws provide for final and jail terms as penalties.