Federal officials are preparing to file a series of unprecedented lawsuits against companies that have been involved in the disposal of hazardous waste at sites around the United States.

Attorneys for the Justice Department and the Environmental Protection Agency have been studying more than 100 sites that have been identified as containing a wide variety of material that could pose health problems to those nearby.

Last November the EPA released a list of 638 sites identified as containing hazardous waste. Federal officials have estimated that the cleanup bill for these and additional waste disposal sites may run into the billions of dollars, but they have not determined who will pay it.

The waste disposal problem has led to massive cleanup bills in the highly publicized Love Canal case in Niagara Falls, N.Y., where the cost is estimated in the tens of millions of dollars, and in additional multi-million-dollar problems in several other states. EPA officials have claimed that the government should not be responsible for paying the cost of removing waste generated by private companies.

Assistant Attorney General James W. Moorman said yesterday that he expected requests for suits against companies responsible to be made by EPA within a month.

In the case of lawsuits filed by the Justice Department's Land and Natural Resources Division, Moorman said his agency has to wait for specific requests for the lawsuits from EPA before they are filed. EPA officials and attorneys from the Justice Department were looking at a hazardous waste site in Kentucky yesterday, a spokesman for the EPA said.

The site, known as "the Valley of the Drums," is just outside Louisville, and contains some 200,000 leaking drums of toxic material. Federal officials said the site was one of several being closely studied to attempt to identify the companies that created the waste.

Moorman said attorneys from his department and from EPA had formed a "think team" to consider what kind of action to take against companies involved in the waste dumping.

"This is an untested area of the law," Moorman said. "We don't know yet what we can or cannot do. But we are getting ready for what we have been told will be requests for lawsuits from the EPA."

Lisa Freedman, an EPA attorney, said yesterday that the agency is uncertain whether it can prosecute hazardous waste-creating firms under the 1976 Resource Conservation and Recovery Act.

EPA officials have said in the past that the act contains no provision for a retroactive application against companies that created or dumped hazardous waste. Freedman said, however, that the possibility of using the act against those firms is still under investigation by the EPA.

One of the questions under consideration by the federal attorneys is whether large companies which generate hazardous material in their operations can turn it over to a contract waste disposal company and then be absolved of responsibility for where it ends up.

A number of such contract dumping firms have taken waste in the past from some of the nation's largest companies and illegally disposed of it. Then the dumping firms have gone out of business, leaving the government with no one to pay for the cleanup.

"We are trying to determine whether these small fly-by-night outfits are actually contractual employes of the big waste generators," Moorman said.

Gus Conroy, director of the EPA's toxic pesticides enforcement division, said yesterday that the waste generating companies are the targets of the planned lawsuits.

"We are looking at these sites, and if they pose an imminent hazard then we're going to ask Justice to prosecute," Conroy said.