The chairman of the Fairfax County School Board said yesterday she will urge the panel to drop an intermediate school in the Centreville-Clifton area from its proposed five-year construction plan and add renovations at some high schools that are more than two decades old.

"I still don't see the justification for the new intermediate school," Chairman Mary E. Collier said. The 1,000-student school is proposed to open in 1991-92.

Collier said the school will be needed eventually, but not as soon as school planners forecast.

"My feeling would be to do some more high school renovations, so more attention is being given to the older schools," she said.

Collier's move is designed in part to address the simmering issue of equity among different parts of the county. At the fast-growing western edge of Fairfax, new schools are rising and more are proposed. But parents in the built-up eastern and central neighborhoods, who are an important source of votes for any school bond referendum, complain that their classroom buildings do not meet modern standards.

Collier said she will lobby fellow board members for support before Thursday's scheduled vote on a capital improvement plan proposed by Superintendent Robert R. Spillane to cover fiscal years 1987-1991.

The proposal, revised from an earlier draft after a public hearing and comments by board members, would spend $181 million, down slightly from the earlier $182.8 million version.

Under the new plan, the county would construct seven elementary schools, one intermediate school, 11 elementary school additions and three special education centers by 1992. Also proposed are extensive renovations to 10 elementary schools, two intermediate schools and two high schools, as well as gyms and music rooms at 11 other elementary schools.

The construction would accommodate a baby boomlet in the county schools, as well as special programs that require additional classrooms. Approval by the Board of Supervisors and voter passage of a bond referendum would be required to pay for it.

Collier said she has asked school staff members for estimates of the cost of adding older high schools to the renovation list, instead of building the $14.2 million intermediate school. Major renovations would include new plumbing, heating and lighting, expanded and modernized libraries, improved laboratories and the addition of safety features such as smoke detectors.

Maggie Van Winkle, a spokesman for Langley High School parents who favor renovations, said Langley, Jefferson and Falls Church high schools all were built before 1965, Herndon and West Springfield in 1965, and Oakton in 1966.

Van Winkle, who testified on behalf of her school's Student-Parent-Teacher Association at the board's public hearing on its construction plan last week, said her group estimates that adding four older high schools to the two already proposed for renovations would cost an additional $24 million.

The superintendent's staff already has made several other changes in the proposed plan. They include dropping a proposed elementary school off Beulah Street, although school planners say it eventually will be needed. Substituted for it was a proposed 36-room elementary school to open in 1989-90 west of Rolling Road and north of Pohick Road, on a site tentatively called "Saratoga." Assistant Superintendent Alton C. Hlavin said bus transportation is easier to Saratoga.

The revised proposal also calls for postponing for two years, until 1990-91, a 10-room addition to Rolling Valley Elementary School and advancing the opening date of the "Sangster branch" elementary school in West Springfield by a year, to 1988-89, because of the neighborhood's fast growth.

The revisions also would postpone opening of an elementary school, to be located at an undetermined site between Braddock Road and Lee Highway, for one year, to 1989-90, and drop plans for six-room additions to the Fairfax Villa and Bush Hill elementary schools.