A nonprofit foundation and a Northern Virginia development company are seeking $4.7 million in federal housing funds to build a low-cost apartment complex for the elderly in eastern Prince William County.

The Fellowship Square Foundation, in cooperation with Ridge Development Corp. of Woodbridge, has applied for funds under the federal Section 8 subsidized housing program, which so far has been immune from presidential budget-cutting.

If the funds are approved, the Foundation, a 16-year-old Lutheran lay group, and Ridge Development would build a 100-unit apartment complex for the elderly and disabled near Occoquan. Under Section 8 rules, residents in the project would pay no more than 25 percent of their income for rent, with the difference between actual rental costs and what residents pay being made up through federal funds.

If approved, work on the project could begin as early as next winter with occupancy expected in spring 1983, according to Foundation officials.

Fellowship Foundation, a private, nonprofit group with headquarters in Reston, manages a similar 464-unit project in Reston called Fellowship Square. Like the Reston complex, the Prince William project would be open to any qualified individual and would include one-bedroom units only.

Prince William has several hundred units of low-income housing for the elderly, far short of the county's needs, say county officials.

Tony Sala, vice president of Ridge Development, who says he was sold on the idea after looking at Fellowship Square in Reston, says the proposed housing complex would be on the banks of a man-made lake planned by developers and within walking distance of convenience stores.

John A. Scherzer, president of the Fellowship Square Foundation, says affordable housing for the aged on fixed incomes is sorely needed in Prince William County.

"This area is a new community with younger and middle-aged people -- people who ought to have their parents nearby, although perhaps they don't actually want to live together," he said.

"We figure we'll have 25 to 30 applications for every unit available," Scherzer predicted.

Zoning for the project already has been approved by the Prince William Board of Supervisors. If federal funds are approved, a more detailed development plan will be presented to the supervisors for approval.