A federal judge, criticizing what he called the Justice Department's "shabby treatment" of a Fairfax County paving executive, swept aside government objections yesterday and gave the businessman a suspended one-year prison sentence for rigging Virginia highway contract bids.

District Judge Richard L. Williams rebuffed arguments by prosecutors that the executive, Bobby J. Surface, who pleaded guilty yesterday to conspiracy, should receive substantial prison time as a message to those "who swindle large amounts of money." Williams gave no explanation from the bench for his action, except for his reference to "shabby treatment."

The judge said later, outside court, that he believed it "almost seemed Justice wanted to set Surface up" in its handling of testimony before a grand jury that has been investigating alleged bid rigging on Virginia road projects since last September.

The sentence left Justice lawyers "not happy," one federal antitrust lawyer said afterward. Earlier bid-rigging convictions have resulted in prison terms ranging up to 150 days and heavy fines for several Virginia businessmen implicated in alleged violations of the Sherman Anti-Trust Act going back at least five years.

Williams denied last week a request by lawyers for Surface, an official of Superior Paving Corp. of Centreville, to dismiss his client's indictment based on Justice's handling of the investigation.

According to court documents, Surface and a fellow Superior employe, Ronald White, were granted limited immunity in exchange for their grand jury testimony last September. Such immunity does not shield witnesses from later prosecution, but restricts prosecutors from using their testimony against them.

White and Surface later met and "refreshed each other's memory" about Superior's past pricing practices, the documents said. White subsequently gave grand jury testimony, but Surface was never ordered to appear before the panel. Surface was indicted last month, in part on the strength of White's testimony, according to court papers.

In an order issued last week, Williams agreed to suppress White's evidence allegedly incriminating Surface and admonished Justice "to handle the problems created by immunity properly in the future."

Surface, who was to have gone on trial July 6 in Alexandria, acknowledged yesterday he conspired between 1977 and 1979 with another Superior executive and other firms to submit illegally fixed bids to the Virginia highway department for paving work in four Northern Virginia jurisdictions.

The alleged conspiracy included secret meetings by various executives at the Washingtonian Motel in Gaithersburg and the Tysons Corner Holiday Inn, some of which Surface attended, Justice attorney Hays Gorey Jr. said.

The president of Superior, Barton S. Mitchell, also pleaded guilty to conspiracy recently in Alexandria and is now serving a 150-day sentence at the federal prison in Allenwood, Pa. Superior was fined $250,000 in the case.

A sealed plea agreement between Justice and Mitchell, made public earlier this week, revealed that another paving firm headed by Mitchell, E. Stewart Mitchell Inc. of Baltimore, has agreed to plead guilty to an antitrust violation in Maryland and pay a $350,000 fine.

Also, Vernon E. Dasey, president of the Bituminous Emulsion Co., a firm owned in part by Mitchell, has agreed to enter a conspiracy plea in Pennsylvania. Dasey will be sentenced to two years in prison with all but 60 days suspended under terms of the plea agreement.

Besides the one-year suspended sentence, Williams placed Surface on probation yesterday and ordered that he perform 300 hours of community service.