Two area developers plan to build about 800 town houses and condominium apartments on nearly 85 acres of the Chiles Tract, one of Northern Virginia's best known pieces of undeveloped property.

Final development plans have been submitted to Fairfax County authorities, who are expected to approve them. Zoning changes to permit construction of the homes, offices, a hotel and retail buildings on the 334-acre tract were approved a year and a half ago over the opposition of residents in the area. Homeowners predicted that the proposed development would result in giant traffic snarls, overcrowding in schools, and the construction of tall buildings that would ruin the rural character of the area.

The Chiles Tract is named for the late Earl N. Chiles Sr., a Virginia country merchant who bought it in 1924, sold off pieces of the property in the 1930s, but retained some of the most strategic land. The tract is bisected by Rte. 50 and bounded on the west by the Beltway. Its location at the intersection of two major roadways and the presence of the Dunn Loring Metrorail station less than a mile away make the property highly desirable. The subway station is scheduled to open in 1986.

Two Canadian development corporations bought the tract, with Cadillac Fairview Corp. taking the southeastern quadrant of the Rte. 50-Beltway intersection and Costain Washington Inc. buying the northeastern section. Then both companies sold areas marked for residential development to two Northern Virginia builders.

Sequoia Building Corp. purchased 33 acres for residential development from Cadillac Fairview Corp., which plans to erect office buildings, retail facilities and a hotel on the remaining 145 acres. In a joint venture, Cadillac Fairview and Wills and Plank Inc. of Vienna will develop four single family, detached homes, and 36 single-family townhouses in the southeastern section of the property.

Carr Properties Inc. will build townhouses and apartments on the approximately 50 acres it purchased from Costain. The Canadian company also will build office and retail complexes on the approximately 100 acres.

Spokesmen for Sequoia, of Fairfax City, and Carr Properties, with headquarters in Annandale, said the two builders expect to start work in mid-1983.

A portion of the homes and office buildings on the Carr-Costain property will cluster around a 15-acre lake the two firms plan to develop. John Cowles, president of Carr, said his company's approximately 400 residential units will be priced from $70,000 to $135,000. He expects the real estate market to improve soon and said that he is "relatively optimistic that long-term funds for construction will be available at a reasonable rate," Cowles said.

The Sequoia housing in the southeastern quadrant will be worth about $28 million and will be priced from about $50,0000 for efficiency condominiums to $70,000 and more for two- and three-bedroom units. Town houses will be more expensive. Sequoia also plans to build a small lake in the residential neighborhood. Ray Smith, president of Sequoia, believes the "market will recover slowly," and in time to bring the buyers to his property.