Fairfax County Executive J. Hamilton Lambert and School Superintendent Linton Deck yesterday proposed giving county workers, including teachers, a 9.1 percent pay raise.

Their recommendation, made in a surprise appearance before the County Board of Supervisors, would cost taxpayers $37.8 million. It is the first time in recent years that the county and school administrations have made a joint announcement on salary proposals.

The proposed wage increase would have to be approved by the school and county boards before going into effect next July.

"I should emphasize that the 9.1 percent represents nothing more than a recommendation which must be factored into the proposed budget," Lambert said during his presentation to the board. He said there would be "ample opportunity" for the community to react to the proposed increases.

The salary announcement received mixed reactions from the two county teacher organizations that had held discussions with school administrators for two months over wages and working conditions.

The Fairfax Education Association, the largest teacher group in the county, initially asked school officials for a 30-percent pay increase for county teachers next year. The rationale for the steep increase was previous losses by teachers to inflation.

William Costello, president of the association, said yesterday that after an intensive round of discussions on Friday, his organization agreed to support the 9.1 percent salary proposal.

The rival Fairfax Federation of Teachers did not agree to the proposed increase. The federation originally had requested a 17 percent raise next year and told school officials that any increase less than the expected cost of living (12.2 percent) would be unacceptable.

"For a one-year increase in rough times [9.1 percent] is not bad," said Rick Nelson, president of the federation. "But a 23-percent loss to inflation in nine years . . . that's the rub."