With stated reluctance, the Loudoun County Board of Supervisors last week approved a 69-acre subdivision on the Blue Ridge Mountains northwest of the town of Round Hill, despite a unanimous recommendation from the planning commission to deny the application.

The supervisors said they approved the subdivision because the subdivision ordinance in effect on Nov. 1, when the application was made by the Sunny Ridge Development Corp., required them to do so.

Supervisor James Brownell, whose Blue Ridge district includes the new subdivision, moved to deny the application on the ground that the mountain ridge is an "environmentally critical and sensitive area of the county." Because of this, he said, the provisions in the new ordinance are subject to discretion on the part of the board.

Supervisor Ann Kavanagh supported Brownell's motion.

According to members of the county's staff, the ordinance, under which the Sunny Ridge development probably would not have been approved, was passed by the board on Nov. 5, four days after the application, and became effective Dec. 1.

Supervisor Thomas Dodson, echoing the sentiments of the other three supervisors who voted with him for approval, said: "My heart is with Mr. Brownell. But given the legal framework we're provided, I think we have to go forward with this."

The original application called for 15 houses to be built on the property, but Woodrow Turner, attorney for the developers, told the board that his clients would agree to change the boundary lines and decrease the density to 11 lots if the application were approved. The land is zoned R-3, which means that one house may be built on every three acres of land. The developer will not build houses, but will sell the lots.

The dilemma has sparked a request by the board to the planning staff to draft a new subdivision ordinance that will provide guidelines for developing environmentally critical areas. County planner Bill Ramsey indicated that such a draft could take the better part of 1985 because of a crush of zoning matters currently facing the staff.

"We are looking at the other 10 Northern Virginia counties that have the Blue Ridge running through them, to determine what they've done to protect the mountain ridges," he said.

In opposing approval of the subdivision, Brownell cited planning commission Chairman John Sleeter's warning that it would lead to erosion and sedimentation from water run-off, pollute the ground water and deplete water supplies.

Sleeter said later that another reason the planning commission recommended denying the developer's application was the condition of the road leading to the subdivision.

"That road Rte. 761 is substandard already," Sleeter said. "The subdivision will double the use of the road and the developer doesn't have to proffer provide road improvement to get a subdivision approved."

Usually a developer will offer to make certain improvements only during the rezoning process. The Sunny Ridge development will not have to go through that process, since the land was zoned R-3 before the developers bought it.

Sleeter, the planning commission's Blue Ridge representative, chastized the board for "giving up too soon."

"They could have exercised more will and greater authority," he said. "Now a precedent has been set that did not need to be set. There will be fallout from this."