PORTLAND – The cost of closing Brunswick Naval Air Station and other bases is going to be much higher than originally projected.

A report by the General Accounting Office says the Defense Department’s projected cost of closing and realigning bases has grown by 48 percent since the base closing commission reached its costs and savings estimate in 2005.

The costs of closing Brunswick Naval Air Station have grown from $193.2 million to $255 million, an increase of 27 percent, the GAO said.

The Defense Department hopes to save $115 million a year in Brunswick alone when the base closes in 2011. All told, however, the Defense Department may have overestimated its annual savings by $1.85 billion for all base closures, according to the GAO report.

Sen. Susan Collins, who sits on the Armed Services Committee, said the GAO report confirms her suspicions that the Defense Department underestimated potential costs and overestimated savings to the Base Realignment and Closure Commission.

“I am concerned that these cost overruns are not only a potential waste of taxpayer dollars, but also confirmation that the Department of Defense’s case to close [Brunswick Naval Air Station] was flawed,” Collins said in a statement.

The GAO estimated it would take until 2017 for the Defense Department to recoup its closing costs, four years later than expected. The report puts annual savings after that at $4 billion a year, but even that could change.

Collins said she has been told an Armed Services subcommittee likely will convene hearings in the new year to look into the matter. “I think that it is important that the Department of Defense be held accountable,” she said.