Willard Wirtz has been a labor lawyer for more than 40 years, so it's understandable that he takes a relaxed view of what looks to others like a crisis.

As chairman of the D.C. Public Employee Relations Board, the former secretary of Labor could turn out to be the man in the middle of an upcoming test of strength between the city workers unions, which are demanding big pay increases, and D.C. Mayor Marion Barry, who wants to hold them off for two years.

But Wirtz, puffing on a pipe and leaning back in his chair, seems unperturbed. "there's a fascinating thing going on here," he said of the District government and its employees. "They're trying to learn self-government at the same time as they learn collective bargaining." His immediate concern, he said, is that the "statutory situation makes it difficult for collective bargaining here to get off on the right foot."

The "statutory situation" he meant is the working and scope of the city's "Comprehensive Merit Personnel Act" of 1978 -- the law intended to regulate every aspect of labor relations for city workers now that they are no longer part of the federal civil service. The law runs to 354 typewritten pages and took years to draft, but labor experts now agree that any negotiations conducted under its provisions are doomed to fail because of disagreements over what the law actually means.

They believe that before negotiators could get around to discussing wages and hours, contract talks would run aground over such questions as who is covered, which bargaining units represent which workers and which issues are subject to negotiations.

Barry, striving to balance the District budget and save money, has not committed himself to any general increase for the city's 31,000 employees, though their federal white-collar counterparts will get a 9.1 percent cost-of-living boost Oct. 1, the first day of the 1981 fiscal year.

The mayor also has included no money for salary increases in the budget he has prepared for fiscal 1982. Unions representing city workers accustomed to salary parity with federalworker have predictably rejected Barry's proposals and hinted broadly that they would go to court to challenge him if necessary. The new law requires the mayor to engage in collective bargaining with the workers, but the legal machinery for conducting negotiations is not yet in place, and almost certainly will not be until well after Oct. 1.

The law created a five-member Public Employee Relations Board (perb) that is responsible for designating bargaining units for city workers based on their "occupational groups" (not necessarily the unions to which they belong, since most unions include different types of workers), and for mediating or arbitrating any negotiations that reach an impass. The members, in addition to Wirtz, are labor lawyers Nicholas Zoumas and Karl W. Carter Jr., customs lawyer Barbara Whiting-White, and real-estate manager H.R. Crawford, who last week was the apparent winner of the Democratic primary for the D.c. cIty Council seat from Ward7.

At a PERB meeting last week, Carter said the Barry administration was "very sensitive about those negotiations and afraid they'll have a runaway pro-labor board here." But Wirtz said that "we're not going to protest our virture in advance. The test will be in the way we handle the case."

The "case" is not pay negotiations, to which PERB will not be a direct party. Rather it is establishing a framework for negotiations that will be acceptable to "management" -- that is, Barry and city labor negotiator Donald Weinberg -- and the unions, and persuading all the participants to stay out of court while the ambiguities and inconsistencies in the law are resolved. The members all agreed that litigation over the terms of the law -- especially on the question of whether city workers are still entitled to pay parity with federal workers -- could result in judicial intrusion on what should be the decision-making power of a home-rule city government.

Last month, Wirtz sent out a deceptively chatty and informal letter to 18 city officials and heads of city workers unions, inviting them to a meeting this week to discuss the "increasing realization on all sides that the Comprehensive Merit Personnel Act of 1978 leaves

He proposed that "a number of us with special interest in this subject get together more or less informally and just talk this matter through -- in general terms to begin with and then more specifically if the conversation seems to warrant." The purpose of the meeting, he said, would be to reach agreement on proposals to amend the law that could be recommended to the City Council.

"there are a lot of anomalies when you try to reduce what is essentially a human relationship to law," Wirtz said. "There are bound to be some difficulties. This is particularly true in collective bargaining, which is an area that the public generally sees only when it breaks down."

Among the problems with the law cited by expert analysts are conflicting languages over whether bargaining on wages must be simultaneous with negotiations on working conditions, imprecise language on the scope and timing of court action and a lack of guidelines for selecting bargaining units for the workers. For example, one expert said, it is not clear whether "public safety" workers, who are to be represented by a single bargaining unit for the workers, who are to e represented by a single bargaining unit, include prison guards and firefighters as well as police officers and city government security guards. Wirtz's panel must make those decisions for every group of workers before collective bargaining can legally begin.

Zoumas acknowledged that those deliberations and attempts to amend the law could well be overtaken by events on Oct. 1. Unions representing city workers have made it clear that they will not easily settle for less than their federal counterparts are receiving, while Barry's inflexible position is that the absolute maximum they could get for the coming year is a raise of 5 percent, far less than the inflation rate.

If the unions cannot be persuaded to refrain from pressing their demands in court until the PERB can organize formal bargaining sessions, the issue may be taken out of the city's hands. Informed sources said that even if the unions do hold off, they will surely demand that any pay increase subsequently awarded be made retroactive to Oct. 1.