The Environmental Protection Agency is preparing to propose acceptable levels of contamination from hazardous-waste landfills, saying that Congress did not intend to eliminate all risk when it tightened the waste-disposal law in 1984.

The proposal, expected to be released next week, already has drawn heated protest from environmentalists and some EPA employes, who called it a "travesty" that will give landfills federal permission to pollute ground water.

EPA officials defended the proposal, which essentially would set an acceptable level of a given contaminant 500 feet from a disposal facility and then work backward to determine how much material containing that contaminant could be dumped in the facility.

According to the agency, the 500-foot distance would assure that no one living near the facility faced an "unacceptable" health risk.

"We think this is a protective rule, an extremely conservative rule," said Eileen D. Claussen, director of the division that wrote the regulations. "This is a very good rule."

In an internal memorandum, however, an agency analyst accused the EPA of going out of its way to avoid complying with the new law, which says that no materials may be placed in a landfill or injected underground unless the EPA believes "there will be no migration of hazardous constituents . . . for as long as the wastes remain hazardous."

EPA "seems more concerned about minimizing the impacts of these clear statutory directives than it is in minimizing the threats of continued land disposal," said a memo prepared by EPA analyst Michael Burns, who has worked on the regulations since the tougher Resource Conservation and Recovery Act was enacted more than a year ago.

According to Burns' memo, EPA data indicate that the distance from landfills to points of potential human exposure is less than 500 feet at nearly 75 percent of all facilities and less than 100 feet at half the facilities.

Claussen said the distance in the proposal was aimed at controlling contamination of drinking water, and the agency was not aware of any wells within 500 feet of a hazardous-waste facility.

Burns' criticisms were echoed by the Environmental Defense Fund, which accused the EPA of drafting a "technical monstrosity and a bastardization of congressional intent."

According to EDF scientist Linda E. Greer, the proposed regulation would allow landfills to leak trichloroethane (TCE), which has been linked with increased birth defects in an area of California's Silicon Valley, "at levels at least 6,500 times EPA's own health standard of 15 parts per billion."

The environmental group also accused the agency of making "completely unrealistic" assumptions about the safety of landfills.

EDF attorney David J. Lennett said the EPA assumed, for example, that all landfills are double-lined and contain equipment to collect and treat leaked material, although few facilities have such advanced systems, and that the systems will perform perfectly for at least 40 years.

The proposal also is based on the assumption that only water-soluble chemicals will escape from a landfill, he said, even though nonsoluble materials such as waste oils have been found in ground water near land disposal sites.

Congress was seeking to discourage hazardous-waste landfills and lagoons when it tightened the nation's basic waste-disposal law in late 1984. Land disposal is generally the cheapest and most popular method of disposing of toxic waste, but it is also widely considered the most dangerous. EPA has acknowledged that even the best-engineered landfills will leak eventually.

Members of Congress have not yet been briefed on the proposed regulations, but a Senate Environment and Public Works Committee aide who has seen an outline of the proposal said the agency "seems to have missed the point."

"I think a real good argument can be made that it's blatantly illegal," he said.