The Fairfax Board of Zoning Appeals will decide Tuesday whether to allow the American Horticultural Society to expand its operations at historic River Farm and Wellington Mansion in the Mt. Vernon area.

The society's require for an amended special use permit to build four small connecting office buildings, add 120 parking spaces and enlarge a circular drive on the 27-acre site has been the subject of controversy in the adjacent residential community since the expansion was proposed in January.

Located on the Potomac River, east of Mt. Vernon Memorial Parkway at East Boulevard, the American Horticultural Society has operated its national office from the Georgian style main house, formerly known as Wellington Mansion, since 1973.

A small library and botanical computer center are located in a building that was formerly the servants quarters and kitchen for River Farm. It is to this building that the society proposes to attach, via a covered walkway, the four office buildings to create a horse shoe shaped structure and court yard.

In exchange, the society has offered to give a 300- to 400-foot scenic easement to the National Park Service as a buffer on the East Boulevard side of the property and a 200-foot easement on the river to the state of Virginia.

The proposed buildings would provide offices for non-commercial, non-profit related associations, such as the Botanical Association, in the plant science field.The plan is to build the offices one at a time, according to Thomas Richards, the society's executives director and former chairman of the Arlington County Board.

At the two public hearings before the Planning Commission and the Board of Zoning Appeals recently much of the criticism centered on a fear of increased traffic over narrow residential streets and a concern that the historical preservation of River Farm, once a part of George Washington's Mt. Vernon property, was not best served by the expansion.

The society's immediate neighbor to the south, Gerald Halpin, also objected. He now has an easement on part of the Horticultural Society's existing driveway to reach his own home.

"The park service owes it to the citizens to tell them how they're going to handle the traffic," said Halpin, a developer of the Tysons Corner and Westgate shopping complexes. He complained that county government staff members did not even consider traffic when they recommended that the expansion be approved.

An equal number of residents supported the expansion, saying that it was not a large expansion and that the society's use of the land was better than a commercial use or subdivision would be.

Others critical of the expansion pointed out that when the first special use permit was issued in 1973, the society promised to build a new driveway from Halpin's property. It was never built. Lois Deneke, finance and administrative director for the society, said that the Park Service objects to the northern access because traffic, which now can move directly from the parkway across East Boulevard to the entrance of the River Farm property, would have to go through residential areas.

Hulda Russell, president of the Wellington Civic Association, who said she was speaking as an individual, opposed the expansion at both hearings. She said the society, with the expanded office use, could have as many as 100 employes in approximately 84 cars going in and out three times a day.

"These streets are 15 feet wide or so," she said. "It is bound to have spillover effects."

The Wellington group's board later endorsed Russell's opposition to the plan. One board member said that "the renting of office space would be a commercial use, one previously not allowed along the parkway corridor" and might lead to other commercial ventures in the area.

Col. J.N. Lopez also objected to the expansion at the hearings. He is president of the East of the Parkway Association but he said he did not represent his group at the hearings because the members were divided on a position.

"the Horticultural Society is a business organization. They are going into speculative leasing. They rent the property out for weddings on weekends," Lopez said. "They were given a special variance five years ago but they have not complied with the original variance (in the matter of the northern driveway)." He said that no study was made of traffic impact.

Deneke admits that the ballroom in the main house was rented for 12 wedding receptions on Saturdays last year. "They were all local girls," she said.

The Mt. Vernon Council of Civic Associations, at the recommendation of its zoning committee, supported the proposed expansion with conditions.

According to Sheldon Hoening, who chairs the council's zoning committee, the conditions were that the Horticultural Society accept the scenic easement to the park service and that state group; that the shared raod problem with the neighbor to the south be worked out satisfactory for both parties, and that the Georgian architecture be continued in the new buildings.

At its hearing the staff of the planning commission recommended approval on the condition that each applicant for space in the new offices apply for a special use permit.

All special use permits are issued by the Board of Zoning Appeals but public hearings on the permits may be held by the planning commission as in this case, if the use would affect the master plan of the country.

The master plan now has the 27 acres of River Farm as open space but adjacent zoning in the area is half-acre residential.