The Fairfax County Board of Supervisors approved an unusual and perhaps unique program last night for upgrading a deteriorating trailer park through redevelopment that will give owners loans to buy newer and roomier mobile homes or renovate their old ones.

The project was agreed on after a number of residents of the Woodley-Nightingale Mobile Home Park described substandard and even hazardous conditions in their development on Rte. 1 in the Groveton area. Woodley-Nightingale, with 550 trailers, is the oldest trailer park in the county.

Deirdre Coyne, spokesman for the county housing office, said the project is believed to be the first public redevelopment of a mobile home park in the nation.

In addition to providing loans for purchases and renovations, the county's Redevelopment and Housing Authority plans to acquire the cramped 39-acre park and reduce the number of trailers, many of which date from the 1940s.

The total cost of the redevelopment is estimated by the housing agency at about $7.3 million, but none of it would come from county tax revenues. Fund applications will be made under a variety of federal programs.

With federal community improvement funds, of which $1.6 million already have been committed, the housing agency plans to correct a number of neighborhood deficiencies, including those cited at last night's board meeting by 14-year-old Michelle Giguere, who said:

"We have no place to play except the streets. Small children play in the streets, which is dangerous to both children and drivers. Games, riding bikes, roller skating, badminton, almost any form of exercise is impossible due to heavy traffic. I have never had a place to play, to swim or to enjoy sports except by going out of my neighborhood."

Grace Huffman, a widow who has lived in the trailer village for 29 years, said: "I don't live in a mobile home because I'm trash, I live in a mobile home because I want to live there." Of conditions at Woodley-Nightingale, she said: "It's bad for young people, it's bad for old people."

County housing official Bruce Laval said "many homes are improperly and even dangerously located." The density of the park is 14 persons per acre -- more than double the density at Friendly Village, another mobile home community, near Dulles International Airport.

Laval also said there is "hazardous" electrical wiring, no fire hydrants, deteriorating water and sewer systems and "minimal community services." From 45 to 50 percent of all the trailers are substandard or in need of major repair, he said. No resident disagreed, and many who testified concurred.

Under the plan to reduce the park's density, no one would be relocated without the reisdent's concurrence or before adequate and affordable housing could be found elsewhere, the board-approved plan says.

In another action on housing, the supervisors approved a number of staff recommendations aimed at dealing with the dramatic increase in complaints about new-home construction in the county.

The recommendations call for the state to examine every builder and require local bonding, the establishing of minimum standards on quality of work and for the final inspector to use a checklist geared to a homeowner's expectations.

The Northern Virginia Builders Association, claiming that only a small number of builders are responsible for most of the complaints, criticized the staff report for "inaccuracies, inadequacies and misleading information."