Toxic Waste Cleanup to Cost Billions : Environment: Congress has provided $10.1 billion. Estimates go as high as $500 billion. And some sites may be too expensive ever to renew.

No one can say how much the final bill will be for cleaning up the hazardous waste sites dotting neighborhoods, industrial parks and federal land across the country. Congress has appropriated $10.1 billion so far for the Superfund program alone, but even conservative estimates put the final price tag at four to five times that amount.

Most independent estimates are far higher.

The congressional Office of Technology Assessment said last year that cleaning up the nation’s hazardous wastes will take 50 years or more and cost as much as $500 billion--longer and costlier than the savings and loan bailout and the equivalent of $2,000 for every man, woman and child in the country.

Reaction to the figure has been skeptical, but there seems to be some support for it.

The White House budget office said cleaning up thousands of facilities and sites owned by the federal government will cost $140 billion to $200 billion over 30 years. These sites, which include about 10% of the Superfund locations, range from domestic military bases and nuclear weapons facilities to legal and illegal dumps on public land.

Some sites may prove too expensive ever to clean up. Radioactive contamination is so extensive at the Energy Department nuclear complex in Hanford, Wash., that cleanup estimates run as high as $40 billion. In May, the Congressional Budget Office warned that Hanford may have to be sealed off forever, creating what’s called a “national sacrifice zone.”

No solid figures exist for the ultimate overall cost because the extent of the pollution is unknown. Consider these uncertainties:

* The EPA expects to add 900 new sites to the Superfund list by the end of the decade, but the Office of Technology Assessment predicts that 8,000 will be added to the present 1,218. Estimates of the number of sites deemed not serious enough for Superfund but still requiring cleanup range from 30,000 to 425,000.

* The average cost of cleaning a single Superfund site is approaching $25 million. But, when six environmental groups and an association of waste-treatment companies studied all 1987 cleanup decisions by EPA, they found that fewer than one in 10 employed methods designed to reduce contamination as much as possible, as required by law, creating the possibility that some sites may have to be cleaned again.

* The Defense Department, a major polluter at its U.S. bases, has not even surveyed contamination at U.S. military facilities on foreign soil even as it begins to close such bases worldwide.

What is certain is that the scope of the problem was underestimated in 1980, when Congress created Superfund. It was a crash response to the national panic generated by disclosures of waste dumps such as Love Canal in Niagara Falls, N.Y., where 1,000 families were evacuated from land that was oozing chemicals.

The mission was to clean up land and water so contaminated that they threaten health and the environment, and the expectation then was that it would be done in short order. But, as former EPA Administrator Douglas Costle observed: “Love Canal was merely the first detonation of a long string of chemical time bombs literally strewn across the nation.”

Defusing those time bombs has proven far more expensive and difficult than expected.