Rita M. Lavelle may have violated Environmental Protection Agency regulations while she headed the agency's hazardous waste cleanup program by allowing representatives of the chemical industry to pay for frequent meals at some of Washington's most expensive restaurants, according to the agency's ethics officer.

Lavelle also may have ignored a longstanding policy against private meetings with companies that could be potential defendants in agency enforcement matters.

An Oct. 7, 1981, memo from William A. Sullivan Jr., EPA's enforcement counsel at the time, has been circulated widely inside the agency. It says EPA officials should consult with the Justice Department "before contacting defendants in enforcement litigation or potential defendants in a matter that may be referred to the Justice Department ."

"Failure to observe proper practice in this regard can . . . ultimately diminish the prospects for satisfactory enforcement of environmental laws," the memo says. An EPA spokesman confirmed that the policy remains in effect.

Industry officials whose names appeared on Lavelle's calendars and were reached yesterday said they were not discussing their company's cases, but were simply talking about issues of widespread interest to the chemical industry. Lavelle did not return repeated telephone calls.

Six congressional panels are investigating the activities of Lavelle, whom President Reagan dismissed Feb. 7 as head of the hazardous waste cleanup program, and the possibility that Lavelle and other EPA officials negotiated "sweetheart deals" with firms rather than force them to pay their share for cleaning up hazardous waste sites. Lavelle had primary responsibility for the $1.6 billion "Superfund" hazardous waste cleanup program.

Her appointments calendars, which were turned over to a Senate committee Wednesday night, read like a Who's Who of the American chemical industry. They contain multiple notations of office meetings, lunches and dinners, some including Lavelle and several of her staff members, with officials of industry.

According to the calendars, she met with representatives of Monsanto, Dow Chemical, the Chemical Manufacturers Association, Chevron USA, Du Pont, Union Carbide and Allied Corp., among others.

Don Nantkes, EPA's ethics officer, said yesterday, "General government regulations on employes' responsibilities and conduct say employes are not allowed to accept meals or anything of value from anyone dealing with their agency or regulated by the agency."

He said the EPA and many other federal agencies allow an exception so that a federal employe may "accept food and refreshments of nominal value on infrequent occasions," but only during a legitimate business meeting.

"Whenever I'm asked, I say that means that if you're at a plant in the middle of a meeting and you go to the corporate dining room and there's no provision for separate billing, or if you're in a meeting and someone sends out for sandwiches--okay.

"But I've always underlined that you're not allowed to accept business lunches . . . . I don't like the appearance of it at all," he said.

Lavelle's calendars show that she was scheduled to meet at least 14 times last year with Charles L. Sercu, an employee of Dow Chemical Co., which deposited poisonous chemicals in at least one dump ranked by the EPA as one of the most dangerous in the country.

According to the calendars, the meetings were almost always over dinner. One of the dinner meetings with Sercu was also attended by Wayne C. Jaeschke, an official of Stauffer Chemical Co. Inc., on the night before the EPA entered into an agreement requiring Stauffer to clean up a hazardous waste site in Woburn, Mass. Dow was one of 120 companies involved in a negotiated settlement with the EPA to clean up the Chem-Dyne site in Ohio.

Sercu wasn't available for comment yesterday, but a Dow spokesman said, "We see no reason to be apologetic for meetings with EPA personnel. Unless the ground rules have changed, the regulated have the right to express their views to the regulators."

Jaeschke, Stauffer's vice president of environmental services, said yesterday that he picked up the tab for the May 24, 1982, dinner at the Four Seasons hotel.

"The discussion had nothing to do with Woburn," he said. He and Sercu and other CMA officials discussed an industry advisory committee for new hazardous waste dump permits and how industry and EPA could work together to solve the problem of finding safe dump sites.

Jaeschke also said Lavelle and several other EPA officials flew to Stauffer headquarters in Westport, Conn., last May 12 for general discussions about Superfund management. In this instance, however, the company did not pick up the tab for air fare, he said. EPA inspector general Matthew Novick went along because "we wanted no thought that there was any special relationship," he said.

Several other businessmen listed on Lavelle's calendars confirmed that they paid for meals for Lavelle and other EPA officials.

Paul Wagner, a Washington lobbyist who is friendly with one of Lavelle's aides, confirmed that he had taken her to lunch three or four times "as a friendly thing . . . . We always try to get acquainted with people." Wagner said he represents companies that have EPA contracts and that "one of our people advised her when they announced the Love Canal thing last fall."

Asked if he paid for Lavelle's meals, Wagner said, "I never knew a PR guy that didn't have to pay the bill."

William Harsha, a former Republican congressman from Ohio, confirmed that he had met with Lavelle a number of times. Harsha, who is now a lobbyist, said, "I represent a company that's actively seeking aggressive implementation of Superfund. We're involved in cleaning up hazardous wastes." Lavelle's calendars indicate at least eight meals with Harsha. He said, "I pay for it. She doesn't pay for those."

Albert Fox, Allied Corp.'s director of legislative and regulatory affairs, said he took Lavelle to lunch at The Palm restaurant last Sept. 7 to get acquainted and to invite her to an Allied pollution control workshop next month. He recalls she had a chicken salad sandwich and a glass of water.

A spokesman for Union Carbide said that George Hanks and Fred Charles from its Washington office took Lavelle, enforcement chief Eugene Lucero and other EPA officials to the International Club for a "get acquainted" dinner on Sept. 14. "We are well aware of our responsibilities and scrupulously avoided any discussions" of pending cases, the spokesman said.

Lucero said last night that he went to that dinner and others at Lavelle's request because he wanted to "to keep Rita out of trouble." He said no specific cases were discussed.

A day after a Senate investigating committee received Lavelle's calendars both Republicans and Democrats immediately complained that there appeared to be erasures on the pages.

A close associate of Lavelle, who asked to remain anonymous, yesterday attributed the erasures to the fact that "she changed her mind. She was always changing her appointments left and right. No one went through and erased anything."