It could be a child's worst nightmare. Imagine someone living in an old elementary school, living out a life there among the plastic green window blinds, yellowed linoleum and sound-absorbant ceilings dotted with aging spitballs.

It's happening, or going to happen very soon, right in Northern Virginia. But it's no nightmare. A plan devised by the Fairfax County Housing and Redevelopment Authority to transform surplus schools into apartments for the elderly was approved last Monday by the Fairfax County Board of Supervisors, and it could prove to be an answer to the prayers of many elderly county residents desparate for better housing.

As Fairfax County's inner areas have aged over the last decade, the population of school-aged children has dropped dramatically, leaving a number of elementary schools empty. Seven county schools already have been declared surplus, and thus can be sold or used for other county purposes. Many more schools still are held by the school system, but are being used for activities other than reading, 'riting and 'rithmetic. These schools could be declared surplus in the future if school populations in those neighborhoods do not rebound.

What to do with these surplus school is fast becoming a problem for the county. Many of the schools are on large parcels of land zoned for residential development, in close-in neighborhoods attractive to developers. Because land in these neighborhoods is scarce, the school sites are valued at any where from $400,000 to $750,000. Some county officials would loke to see the schools sold and the money plowed back into county coffers.

But residents of the surrounding neighborhoods consider these schools community property. As an interim measure, most of the schools are leased for day care centers, senior citizen centers, recreation classes and community meetings, activities that strengthen community ties with the school. And in a county where soccer teams have to scramble to find a playing field on Saturday mornings, the green spaces around these schools provide a jealously guarded benefit for the local neighborhoods.

The Oak Grove elementary school in Herndon has been declared surplus and the county would like to sell it, but Herndon town officials have asked the county to consider deeding the property over tothem to use as a headquarters for the town's 35-person police force.

"The property is worth between $400,000 and $600,000," said John McBride, the county's property management director. "It's a classic problem of the interests of the local community versus the interests of the county as a whole."

Herndon's town manager, however, sees it differently.

"The people of Herndon pay taxes just like everybody else in the county," said Edwin Martin. "If we had to build an addition [to the existing police station], it would cost us $100,000."

The housing authority's plan to convert part of the Lewinsville Elementary School in McLean into apartments for the elderly has attracted interest from other communities with surplus schools, because it is a way of meeting neighborhood and county needs.

The plan, which is the first in the county, will involve renovating the second floor of the school into 21 efficiency apartments while leaving the first floor open to day care programs and other community activities.

The 400-square-foot apartment units will be made by dividing each schoolroom in half, putting in carpeting, kitchenettes and bathrooms, and modifying the windows slightly to soften the institutional look. The school library will be revamped into a community room with cooking and dining facilities, and there will be a resident program manager to coordinate activities for the residents.

The units will rent from about $250 a month, and housing officials are not sure yet how they will select residents other than giving preference to people from the local community. The renovation will cost $300,000, far cheaper than building new apartments. But because the housing authority only has a five-year lease on the space, some board members questioned whether it was worth the expense.

"Housing for the elderly is a top need in this county," said Supervisor Sandra L. Duckworth (D-Mount Vernon). "From the proposal and sketches we saw, it looks like it will be very nice and livable, and this kind of shared living arrangement is wonderful for senior citizens who want support and privacy at the same time."

Duckworth has a particular interest in the success or failure of the Lewinsville project because similar projects are being discussed with community residents for a number of schools in her district, and she believes it is cost-effective, even if the lease is short-term.

"Five years is a long time, and if you cost it out per unit, that isn't much money," said Duckworth. "Not when you consider what you can accomplish by providing housing for 21 elderly residents."

One of the schools in Duckworth's district is the Hollin Hills Elementary School, an aging structure the board of supervisors agreed last week to put up for public sale. Bids are being solicited from more than 50 groups and developers that have expressed an interest in the site on Fort Hunt Rd., and the county board is expected to award a contract sometime this summer.

But Duckworth said she is going to consider the bids carefully and not support an award that is not accepted by the local community. With restrictions on the use of the land and the community's concerns, the county "could very well end up without a bid," even though the land is valued at $750,000, she added.

"We are particularly concerned that they not cut another access road through to the property," said Ruth Dell, president of the Hollin Hills Community Association. "We would like to see the playing fields preserved and possibly get housing for the elderly on the site. We didn't know until the public hearing last week that a developer could build 48 units on the property even though some of the acreage is not buildable. I'm not sure if we would support that, because the traffic on Fort Hunt Road is already so bad."

To protect the surrounding neighborhood from having a developer buy the land as an investment and not actually use or develop the property, the county has built restrictions into the bid proposal for the Hollin Hills site that will allow the board to consider time schedules for development and the longevity of the proposed use when it awards the contract. Under the current zoning, up to four units per acre could be built on the 12-acre site, and the board approved a restriction that will prohibit future rezonings.

But these restrictions could reduce the desirability of the site for developers, and Duckworth said she thinks it is less likely that a private school would want the building.

"I don't know what we would do then," said Duckworth. "Lease it out to community groups again until someone wants it."