The costs of environmental and road studies on a proposed port terminal in North Charleston have shot up to about $5 million from less than $2 million, port officials said Tuesday.

Resigned to the fact that there was no way to avoid the expense, the State Ports Authority signed off on the studies, as required by the U.S. Army Corps of Engineers. The Corps will decide whether the $600 million port project at the former Navy base in North Charleston should be approved.

The controversial project, criticized by residential and environmental groups that say a new terminal will add to congestion and pollution in North Charleston, has been before the Corps of Engineers for more than a year.

The Corps and the SPA, after months of intense negotiations, agreed on a 91-page "scope of work" that outlines all the questions that will have to be answered before the controversial project could get the Corps' approval.

It includes everything from an environmental assessment of how the land and the Cooper River would be affected by a new terminal to how roads and railroads in North Charleston could handle the increased cargo traffic moving in and out of the expanded port.

The Corps now isn't expected to issue or deny a permit on the project until August 2006. The Corps and the SPA said last year they hoped to have a decision on the project no later than December of this year.

The project, however, has been unpredictable from the start.

The new $5 million price tag is more than double what the SPA had estimated it would pay for the studies. Last year, the SPA proposed spending about $1.8 million on the studies.

Engineer Donnie Dukes, who represents the SPA during project negotiations, said some of the Corps' earliest estimates on the study costs were higher than the $5 million.

"Certainly you go in and try to get to middle ground, and that's what we've achieved," Dukes said. "It's based on many hours of negotiation."

An additional $1.3 million was added for the cost of traffic and road studies of the busy North Charleston area, a sticking point for city officials and residents, who question how already-congested roads can make room for another 2,000 trucks a day traveling to a new terminal.

The city of North Charleston has a written agreement with the SPA that a new terminal would open only after new access roads to the terminal from Interstate 26 have been built.

The SPA has said it will be up to other agencies, like the state Department of Transportation and Division of Highways, and to the Legislature, to make sure funding is provided and that those roads are built.

Joe Bryant, SPA vice president of terminal development, said the Corps and the SPA have been working with those agencies to make sure the engineering studies will be sufficient to make new roads a reality.

The North Charleston terminal site was a last-ditch effort by the SPA to expand its Charleston-area facilities after a proposed terminal on Daniel Island was rejected by both residents and lawmakers.

Several board members have criticized the Corps for what they say are unnecessary delays in the permitting process and for adding additional expense to the studies.

The Corps has said all the studies are necessary to determine what kind impact a new terminal will have on the entire region, and that approval for the project is far from guaranteed.

Bryant told SPA members Tuesday that further cost negotiations probably won't speed the process.

"We believe this is what it's going to take to get to the record of decision," Bryant said. "We feel this is what we're going to have to do to get a (permit)."

The SPA had estimated it would take at least five years to build the new three-berth terminal, but road construction in North Charleston also is expected to take years. Port officials, who have seen a nearly 13 percent increase in cargo volume in the past six months, recently said it could be 2012 before a new terminal opens.