Arlington School Superintendent Charles E. Nunley recommended last night turning the county's oldest intermediate school into an alternative education center and closing four elementary schools at the end of the 1983-84 school year.

In a report to the School Board, Nunley also recommended keeping open all of the county's three high schools and changing only their boundary lines to improve racial and ethnic diversity.

As part of a consolidation plan occasioned by declining enrollment, Swanson Intermediate School should be closed, Nunley said, because it is the smallest, oldest and most expensive to operate of the county's four intermediate schools. Nunley recommended that Page Alternative School for elementary pupils be relocated at the Swanson facility. "The reasons for closing it as an intermediate school do not negate its viability as an elementary school," Nunley indicated that although Swanson is small for an intermediate school, it is large enough for the now-crowded alternative school.

Barcroft, Claremont, Reed and Tuckahoe elementary schools would be closed, under Nunley's proposal. He said they were selected because of their size and marketability, a concept Nunley has called relevant if the system is to lease the closed school buildings.

Nunley's recommendations came a week after board members directed him to more clearly specify reasons for closing schools identified in an earlier report. At that time, Nunley suggested only that the system maintain its current method of grouping students in elementary, intermediate and senior high schools.