The State Ports Authority board took the next step Tuesday in converting a 108,000-square-foot warehouse into a modern cruise terminal in downtown Charleston.

The group voted to approve a contract with international consulting firm CH2M Hill for as much as $250,000 for cost estimates, conceptual design and a schedule by mid-October. Port officials set a preliminary price for the entire project at $25 million.

The SPA plans to move its cruise operations from a nearly 40-year-old building to a considerably larger cargo warehouse farther north on Union Pier Terminal, where workers could handle passengers, ship supplies, baggage and security in one place.

Denver-based CH2M Hill must consider not only the relocation and its architectural needs but seismic upgrades to the building and also U.S. Customs and Border Protection requirements.

The firm previously performed nearly the same task at the Port of Galveston in Texas, converting a warehouse to a cruise terminal, according to Joe Bryant, the SPA's vice president of terminal development.

Bryant said CH2M Hill officials expect the building's existing footprint to work well with the project.

"They feel that the building size is comfortable," he said. "That was the term they used."

The cost estimate comprises $205,000 for professional services and $45,000 in reimbursable expenses.

The contract marks an early step in an ambitious plan to relocate SPA cargo operations out of the historic district, to move cruise business farther north and to connect Market Street with public access to the Cooper River.

The redevelopment of Union Pier Terminal would remove from the tourist-rich area 200 cargo ships per year, two or three trains each day and 1,800 trucks and cars every week.

The projected time-line calls for a request for proposals from architects by year's end and a start to construction a year later. The new cruise terminal would open in the third quarter of 2012.

Reach Allyson Bird at abird@postandcourier.com or 937-5594.