The Arlington County Board has approved site plans to allow the construction of an 12 story rent-subsidized aparment building for the elderly on the edge of Rosslyn. Their action came in the face of objections of some residents of the community.

The board voted 4-to-1 to approve the 300 apartment Monticello Place building to be constructed just west of the Xerox building on North Ft. Meyer Drice. If the Department of Housing and Urban Development and the Virginia Housing and Development Authority also approve plans for the building, as expected, construction could begin this spring.

The building, with 300 one-bedroom units, will rent to elderly tenants of low and moderate income, with the median income expected to be about $5,000, according to Larry Suiters, attorney for the developers. The developer is The Beacon Companies, a Boston real estate development, construction and management firm.

If approved as a rent-subsidy apartment building, HUD will pay the developers what is considered to be a fair market rate for the apartments, about $300 monthly, according to the developer's representative. Tenants will pay no more than 25 per cent of their income in rent, with that money flowing back to HUD. The average tenant is expected to pay about $105 monthly in rent, said Beacon's representatives.

The board changed the zoning and adopted the plan for the site after hearing from a small group of residents of the nearby area who said they opposed construction of the building for reasons ranging from expressed concern for the elderly to desire to see the county purchase the land for a park.

"Rosslyn is a dead city at night. It's city of office buildings," said Robert Bamberger of 1502 North 16th St. He said he questioned where the elderly tenants would go for entertainment.

James E. Whelan, vice chairman of the Association for the Preservation of Rosslyn, suggested that the county buy the land for a park, preseving "one of the grandest views in the country." Under questioning by board member Walter L. Frankland Jr., developer's representatives said that the cost to the county for the land would be about $1.5 million and that taxes that might be lost would amount to about $120,000 yearly.

Other opponents said that the terrain on which the building will be erected is so steep that it will present difficulties for tenants walking and that the area is so noisy and ill-served by merchants that it is not suitable for such a building. In one attempt to stem opposition, the developers had agreed to keep part of the development land natural or land-scaped rather than paved.

The grant to build 300 units included a bonus in the form of a 6.8 per cent increase in permitted density from the county because the building will provide housing for moderate income families. The single vote against the project was cast by board member John W. Purdy, who indicated he thought the bonus had been taken too much for granted by the developers.

"I'm very impressed with this project," said board member Ellen Bozman. The building will include a greenhouse and solarium on the roof and will provide jitney service for residents.

"I think the project and the people in the project will make good neighbors," she said.