The Fairfax County Board of Supervisors agreed yesterday to support construction of a housing project in Springfield for low-and moderate-income familiess st ifs size were cut from 100 to 50 subsidized toenhouses. The project's developer promptly called the proposal "unfeasible" and "unrealistic."

David Small whose Pittsburgh-based firm, Housing Affiliates, Inc., is developing the Rolling Road Estates projected the supervisors' idea. "We are building 100 subsidized units or none at all . . . I'm not going to sit down with anybody and talk about just 50 units," he declared. The supervisors called for interspersing 50 subsidized units among at least 50 non-subsidized units.

The next move in the continuing controversy move in the publicly subsidized housing project apparently will come from the Virginia Housing Development Authority, which is scheduled to vote Wednesday whether to allocate $4.5 million in federal funds as a loan to build houses.

The controversy began in October when citizen association representing several neighborhoods near the 35-acre site leaned that the stage agency was about to approve federal funding for constrution. Arguing that the citizens were not properly informed about the project, County Bojrd Chairman John F. Herrity, board membeMarie B. Travesky (R'Sprinfield) and others succeeded in having the state agency delay its deci-

In November, the federal Housing and Urban Development Department threatened to cut off $3.7 million in federal aid to the county if the county blocked the project.

The state agency had aid it will approve funding for the project unless the county determined that Rolling Road Estates fails to confirm to the county'ss housing assistance plan. The board took no position yesterday on the project's conformity to that plan.

Thomas Hobbs, director of HUD's Washington area officesaid yesterday that his department would "be willing to sit down and discuss proposals endorsed by the supervivors for altering the development's =economic mix," but he said "the project will go through as it is no compromise reached."

The porposal endorsed yesterday on a 5-to-4 vote supervisors originated with citizen associations representing several subdivisions - Saratago, Newington Station and Chancelor Farms - near the Rolling Road Estates site.

Current plans for a development of 100 two, three and four bedroom townhouses on the site on Rolling Road. Thirty per cent would be rented to families with low incomes ($10,000 a year or below), and the rest to moderate-income families (for instance, a family of four with earnings between $10,000 and $16,000 a year)

The proposal endorsed by the supervisors calls for "a mix for not more than 50 subsidized units, interspersed among not less than 50 nonsubsidized ownership units." The primary objection to the project, according to the statement adopted by the supervisors is a "100 per cent concentration of subsidized housing in one development.% "

Supervisor Travesky said she thinks "this solution (the boards's proposal) is a reasonable compromise that could satisfy all sides . . . If successful, it would show Fairfax County citizens they have an hand in determine how public housing is developed in the country. Nobody is saying public housing is not needed."

Voting against the board's proposal were Supervisors Martha V. Pennino (D-Centreville), Warren I. Cikens (D-Mount Vernon), James M. Scott (D-Providence) and Alan H. Magazine (D-Mason).