The Arlington County Board decided yesterday to take no chances and continue its campaign against a U.S. Navy proposal to shift 18,000 employes--11 percent of the county's work force--from Northern Virginia to the Navy Yard in Washington.

The board has fought this battle before, most recently in August when the Virginia congressional delegation torpedoed an authorization bill that would have eventually given the Navy $280 million over the next five years to consolidate personnel in Northern Virginia--including 16,500 who work in Arlington--into current or future Navy-owned facilities in Washington.

Despite the setback, Navy officials have not given any indication of abandoning the proposal, which they argue would be "cost-efficient" and "management-efficient" since the Navy would no longer have to lease suburban space and would have all its employes in close proximity.

If enacted, the plan would leave nearly 2.4 million square feet of office space, most of it in Crystal City, vacant.

"We have every reason to believe the Navy is going to raise this issue again," said Board Member John G. Milliken, calling for "vigorous opposition" to the proposal.

Board Chairman Ellen M. Bozman said board members would testify against the proposal at a Jan. 19 hearing scheduled by the National Capital Planning Commission, which has previously indicated support for the relocation, and at hearings Feb. 18 and 19 that the Navy is conducting. The board will also seek to reenlist congressional support and the backing of such regional agencies as the Metropolitan Washington Council of Governments.

The Navy's consolidation proposal surfaced again yesterday when board members received a county staff report that was highly critical of the Navy's draft of a $500,000 Environmental Impact Study (EIS), which is required before Congress can fund the Navy's plan.

The staff analysis, done by Diana Wahl of the county's economic development division, attacks the Navy's study as being "skewed and biased (in favor of relocation to the Navy Yard) . . . (frequently) unsubstantiated and ill-conceived," and often factually inaccurate. It concludes that the study is so prejudiced that "the public is ill-served by this cavalier disregard for the law's intent."

"In the minds of some Navy officials, this is a virtual fait accompli," Wahl said, explaining that the Navy needs "the ammunition [of the EIS report] to go forward."

The staff analysis is particularly critical of the Navy's assessment of the impact a relocation would have on the county's economy, retail and hotel businesses, housing patterns, transportation and development. It also notes that 64 percent of the employes who would be affected live in Virginia.