It was a rather unusual request.

Local governments across the Washington region were in open warfare with each other over sewage disposal, and a federal judge had designated J. Hamilton Lambert, then acting Fairfax County executive, to be the peacemaker. The Blue Plains sewage treatment plant had a limited capacity, and someone had to figure out how to divvy it up.

Lambert walked into the first meeting of 30 or so lawyers, engineers and bureaucrats about 15 years ago, and said simply, "Everybody with a three-piece suit, leave."

There was an uncomfortable silence. A few people looked questioningly at their counterparts. Lambert didn't move or say anything. One by one, the blue and grey pinstripes rose from their chairs, collected their belongings and walked from the room.

"About 10 people got up and left," Lambert said yesterday, relating the tale on his final day as a county employee after 31 years of service. "There were so many attorneys involved in the Blue Plains issue, it was never going to be resolved. They had to stay out of the political and technical issues."

The story is the type that has floated around the Washington region for years and has helped earn Lambert the reputation as "the dean of the Beltway bureaucrats."

Lambert stepped down yesterday after 10 years as county executive, during which he amassed extraordinary power and helped transform the county from a suburban bedroom community into an economic powerhouse and one of the nation's most dynamic growth areas.

The Blue Plains meeting was the start of a process that led to one of the most important regional agreements and ushered in an era of cooperation among the area's local governments. It earned Lambert a special award from the Metropolitan Washington Council of Governments for "a major achievement of lasting significance" to the region.

"There's no way to overemphasize J.'s influence on regional issues," said Walter A. Scheiber, the council's longtime executive director, who also retired yesterday. "He is a tower of strength and leadership in the region and in his own government."

The Fairfax Board of Supervisors has appointed Richard A. King, the former police chief and deputy county executive for public safety, as acting county executive until a permanent executive is selected. The process probably will take at least 18 months. King has said he is not interested in the post on a permanent basis.

Lambert, 50, joined the Fairfax government as an assistant map draftsman in 1959, and despite his lack of a college education, rose steadily through the ranks to become the chief administrative officer in 1980. He decided to retire about two months ago after a salary dispute with the Board of Supervisors, electing to collect a $102,000-a-year benefit package rather than continue in his $129,000-a-year job.

Now, Lambert says, he intends to relax at home for a while before deciding his next career move. "I'm leaving this place that same way I started," he quipped. "Looking for a job."

Yesterday was a fairly normal day that started with an irony: Lambert was supposed to turn in his county-owned car, but when he tried to start it, the battery was dead.

Between routine business about the budget and pending lawsuits, Lambert held court in his office, sharing stories and one-liners, receiving calls and visits from well-wishers, attending a small staff party, and having lunch with Supervisor Joseph Alexander (D-Lee), who has served on the board almost as long as Lambert has worked for the government.

The day offered him a chance for a soliloquy on his years with the county.

"Joe Alexander called me once and said, 'The Annandale library is on fire!' I said, 'I didn't do it.' "

To a question about his immediate plans: "My calendar is as empty as a hermit's date book."

What about the New Year's Eve party in the District? Would the city drop the "Love" stamp from the Old Post Office Pavilion, as in previous years? "They're going low-bid this year," Lambert said. "They're going to drop a postage stamp from the top of the Washington Monument."

How about in 1973, when the previous county executive sent Lambert, his special assistant, to the computer department to help computerize tax records?

"I was resented by the deputy of the department, who didn't think I belonged there," Lambert said. "So they got a desk for me, painted it red, and put it in the middle of the floor. I guess you could say I had a reality check my first day there."

And the deputy? "He's no longer there," Lambert said with a puckish grin. "Some days you get the elevator, some days you get the shaft."

Lambert's comments have not always won him the gratitude of his bosses on the Board of Supervisors, such as the time he told a magazine interviewer that he'd rather be sitting in an Interstate 66 traffic jam on the way to work than be standing in the unemployment line.

But, Lambert said yesterday, he has few regrets. County staff needs to be consolidated more in the human services area, he said. Progress on transportation improvements "was not as rapid as I had hoped." As for affirmative action, "we could have done better, but given all the conditions and circumstances, we've done quite well."

Lambert said he is particularly proud of the county's child care services and some of the major public improvements that he helped create, including the widening of Route 28, construction of the county's new incinerator and the new government center, scheduled to open in about a year.

And the final question, borrowed from his own repertoire: Will the public need a search warrant to find J. Lambert?

"I don't intend ever to retire. I don't think I could emotionally adjust to that," Lambert said. "Let's just say I'm between jobs."