Faced with a serious money crunch, Prince William County budget officials have proposed an austere building plan that calls for spending less than half of what they expected one year ago.

Prince William ordinarily plans major construction projects in six-year intervals and updates those projections annually. Last year, the county announced plans to spend $47.6 million in fiscal 1992, which begins in July. The new plan calls for $20.8 million.

Calling the proposed plan "a major downsizing," County Executive James H. Mullen recommended pushing back or canceling renovations for the Central Library in Manassas, parking for the stadium next to the McCoart building and plans for a 200-bed expansion to the Prince William/Manassas Adult Detention Center.

However, he opted to push ahead with plans for an emergency juvenile shelter, baseball field lights at Woodbridge Senior High School, and design work for a recreation center in the county's western end.

The improvements plan is only a recommendation and must be voted on by the Board of County Supervisors as part of the annual budget process.

If the board agrees with Mullen, the 1992 projects will be financed with $1.4 million from general tax revenue, and the rest of the money would come from user fees and government grants.

In addition, all the road, parks, library and schools bond projects approved by the voters in 1988 would go forward as scheduled, Mullen said. For example, the Chinn Regional Library and Recreation Center are scheduled to open in the fall, and construction has begun on the Prince William Parkway.

Prince William public schools officials won't unveil their improvements plan until Feb. 6, but Associate Superintendent Robert Ferrebee said he does not expect to build any schools in the next year. "Any capital projects we do will be limited to things that are absolutely essential," such as replacing a roof that can't be patched, Ferrebee said. "Whatever we would do on the capital projects will have to be funded from our operating budget" rather than with bonds.

The building plan adopted last year had called for four schools to be built in 1992: one high school, one middle school and two elementary schools.

County budget officials also recommended significantly scaled-back building plans for the next five years. The new plan calls for spending $516 million from 1992 to 1997, while the 1991-96 plan adopted last year anticipated spending $738 million, including funds for several new schools.

"Prince William cannot debt finance any new improvements, including schools, until 1994," Mullen said.

The essential problem for Prince William, budget officials said, is that county policy limits all interest payments on bonds to 10 percent of general tax revenue.

Because revenue has fallen off dramatically this year due to the economic slump, the county can't afford to take on new debt, said budget officer Kathy Lueckert.

The proposed building plan assumes that the county would receive $305.9 million from general property, sales and business tax revenue in fiscal 1992.