Supervisors OK Study of Whether to Replace or Upgrade Courthouse : Expansion: But proposals to add $306-million high rise or build a new $420-million facility may be scuttled by a court ruling that could annul financing.

In the first major step toward expansion of the crowded downtown courthouse, the San Diego County Board of Supervisors on Tuesday approved a study that will examine whether to add a $306-million high-rise to the existing building or replace it with a $420-million facility.

By a unanimous vote, the board selected those two options from among seven alternatives included in a study of the county’s long-term criminal justice system needs--a review that revolves around how, or if , the cramped 26-year-old central downtown courthouse should be used.

However, Tuesday’s board action, which authorized additional refinements of the cost estimates and construction options over the next three months, could be rendered moot by a court decision expected later this summer that could determine whether the county can spend hundreds of millions of projected tax dollars on the project.

Unless the county overturns a controversial 1989 court ruling that invalidated Proposition A, a voter-approved 1988 half-cent sales tax estimated to generate $1.6 billion for new jails and courts over the next decade, the courthouse expansion review could become little more than a frustrating academic exercise.

“Without Prop. A, it isn’t going to happen,” acknowledged Rich Robinson, head of the county’s Special Projects Office. “There’s just no way to proceed with a project of this magnitude without that revenue. It’s going to take Prop. A or Son of Prop. A to finance something this big.”

Last year, a Riverside County Superior Court judge--who heard the case because of local judges’ conflict of interest on a matter affecting future courtroom space--struck down the ballot measure on the grounds that it violated Proposition 13, the landmark 1978 statewide property-tax cutting initiative. The 4th District Court of Appeal heard the county’s appeal of that decision last month and is expected to issue its ruling by September.

While county officials wait and hope for a favorable court ruling, their real-estate consultants, Williams-Kuebelbeck & Associates, and other analysts will proceed with studies aimed at helping the supervisors choose between expansion or replacement of the existing downtown courthouse.

Local judges strongly favor replacement of the existing building, a position underlined by Presiding Superior Court Judge Judith McConnell’s argument that spending more money on the courthouse “would be tantamount to throwing it down a black hole.”

Arguably the most notable among the courthouse’s numerous shortcomings is a lack of space, which has made it necessary for temporary courtrooms to be built in an adjacent downtown hotel and another vacant building. The building also lacks adequate office and support space for purposes such as lawyer-client conference rooms and holding cells, and is plagued by problems stemming from deterioration of its mechanical system and other parts of its infrastructure.

The supervisors, however, wanting to preserve their options, decided to pursue both possible expansion or replacement of the courthouse pending additional review of the cost differences and other distinctions.

Both plans to be further studied under Tuesday’s action envision adding 77 courts and extensive office space to the existing 66-court facility, creating a 143-court building designed to meet the county’s needs until the year 2010.

Of the two options, renovation and expansion would be less expensive, costing an estimated $306 million--about $116 million less than demolition and replacement, according to projections from the Omni Group, a justice system consulting firm retained by the county 20 months ago.

Under the renovation plan, a 27-story tower--equal in height to a 35-story building because of the courts’ higher ceilings--would be built next to the courthouse on the block bounded by A, B, Front and Union streets.

The same block would be used under the second proposal to raze and replace the courthouse, a project estimated at about $422 million. If that option is selected, more court office space will be built on the block to the west, and the valuable property housing the existing courthouse could be sold by the county to raise substantial revenue.

The new courthouse would have 1.9 million square feet, 700,000 more than are available in the renovation-expansion plan and nearly four times the size of the existing structure.

Several other critical factors also will influence the project’s overall cost and feasibility. Consultants have said that a $25-million parking structure also would be needed, and the county’s Central Jail and detention facility--situated in the existing courthouse building--also would have to be relocated. If the courthouse is demolished, the jail obviously will have to be moved, and, even if the building is retained and renovated, the county’s consultants recommend that the jail area be used for storage and office space.

County plans call for the existing 1,000-prisoner jail to be eventually replaced by a 2,750-bed facility in Kearny Mesa on a site once considered for a proposed trash-to-energy plant.