A large chemical waste firm, represented by a lawyer who was then a top adviser to Environmental Protection Agency Administrator Anne M. Gorsuch, was able to dump 1,500 barrels of flammable solvents in a Denver landfill last year after Gorsuch lifted a federal ban on such dumping.

James W. Sanderson, a Denver attorney whom Gorsuch had proposed for the No. 3 job at the EPA, represented Chemical Waste Management Inc. while serving as a government-paid, part-time adviser to Gorsuch from March, 1981, through June, 1982.

On Feb. 25, 1982, Gorsuch acted to lift a Carter administration prohibition against disposal of liquid chemicals in hazardous waste landfills. Gorsuch later changed her mind and reimposed the ban in mid-March after a storm of protest over EPA's procedures and concern that buried drums containing liquid waste eventually corrode, allowing dangerous liquids to leak into nearby ground water.

While the ban was lifted, Chemical Waste Management Inc. was able to dump the 1,500 barrels of flammable solvents for a number of industrial clients into the Lowry Landfill in Denver, one of a dozen such dumps operated by the firm. A congressional investigator has estimated that, at the going rate, the firm could have earned $80,000 for doing this.

An official at Chemical Waste Management Inc., which Sanderson continues to represent, acknowledged at the time that the firm was poised to dispose of the liquid wastes when the EPA officially lifted the ban. The official was quoted by The Wall Street Journal as saying "the stuff's already on site" at the Lowry Landfill.

Sanderson withdrew from consideration for the No. 3 job at the EPA last June after an unrelated investigation into possible conflicts of interest concerning another of his clients, the Denver Water Board, which also was affected by EPA action while he worked as a consultant at the agency.

Sanderson, who is still being investigated about this by the Justice Department, acknowledged in an interview yesterday that he also has discussed with both Gorsuch and EPA general counsel Robert M. Perry the pending contempt-of-Congress case against Gorsuch.

But he said he played absolutely no role in Gorsuch's liquid dumping decisions and that he did not discuss the matter with Chemical Waste or any other legal client. He said he was careful to "wall myself off" from any discussions at the EPA that might affect these clients.

"I was concerned about the conflict issue," Sanderson said. "I notified people in the agency who my clients were. I didn't talk with any of my clients."

He said he was especially wary of the liquid dumping rule because "I knew that was going to be a hot one."

In a confidential deposition taken last year by the EPA inspector general, Sanderson said he "became aware because one of my legal partners told me, that this was an issue that was developing within the agency and I better be careful and stay away from it . . . . "

Rep. James J. Florio (D-N.J.), whose House subcommittee is among six congressional panels investigating the EPA, said yesterday he was concerned about Sanderson "being on two payrolls" during the period when the EPA lifted the ban on liquid wastes without holding hearings or seeking public comment.

"No public hearings were held before they lifted the ban," Florio said. "Sanderson's client company was a direct beneficiary."

The EPA lifted the ban abruptly without holding hearings or seeking public comment.

Sanderson said he talked last month to Gorsuch, whom he called an old friend from Denver, "in general terms about how the flap is going."

He said he was "curious" about the contempt case, which began in December, when Gorsuch refused to give Congress subpoenaed documents, and that Perry provided him with copies of the Justice Department's legal briefs in the lawsuit. But he said he hasn't seen any of the documents being withheld in the case and called suggestions that he was giving Gorsuch legal advice "malarkey."

Chemical Waste Management Inc., one of the largest waste disposal firms in the country, recently received a $7.7 million contract to dispose of wastes at a toxic dump in Seymour, Ind. The EPA has been sharply criticized for agreeing to a settlement in which 24 major companies could escape millions of dollars in potential liability for cleaning up the Seymour site.

Last month the EPA recommended that Chemical Waste be fined $48,000 for several violations at the Lowry Landfill in Denver, including failure to monitor ground water pollution, failure to repair a crack in the facility and failure to keep accurate records.

While dumping liquid chemicals in landfills has proven to be the cheapest method of disposal, companies can legally get rid of these liquids by incinerating them, turning them into solids or, in some cases, allowing them to evaporate in holding ponds. These methods, now being used to dispose of an estimated 500,000 gallons a year of hazardous waste containing liquids, are far more expensive for industry.

While the liquid waste ban remains in effect, the EPA has proposed new rules that would loosen restrictions on such disposal.

Peter Vardy, vice president of Chemical Waste's parent company, acknowledged that he personally wrote "some sections" of the EPA proposal, which Gorsuch published after reimposing the Carter ban last March. Vardy said the EPA adopted some ideas he had offered as a member of a national trade group on hazardous waste disposal.

That proposal would limit the volume of liquid in a hazardous waste landfill to 25 percent, the maximum amount of liquid any landfill could hold anyway for engineering reasons, according to an EPA technical consultant.

Vardy contended that the temporary lifting of the ban on liquid wastes had had a "negligible" effect on his company.

Sanderson said he didn't understand why his year-old activities were receiving so much attention. "I thought I was old news," he said.