Concerns about the possible closure of the U.S. Navy Submarine Base in Groton go beyond the potential economic impact, and the state Department of Environmental Protection is now exploring the possibility that the cost of the environmental cleanup of the base – which would be necessary before the land could be turned over for private use – could exceed the estimation put out by the Defense Base Closure and Realignment Commission.

The Pentagon last month proposed closing the base, but the final decision won’t be made until the end of the year.

The DEP toured the base late last month to find out what already has been cleaned and what more needs to be done, and is now combing through BRAC reports to compare its own findings with BRAC’s, according to Matt Fritz, spokesman for the DEP. BRAC estimated the cost of environmental cleanup to be $24 million, but some in Connecticut suspect the cost could be much higher.

The DEP is exploring the possibility of groundwater contamination on the base and studying the effects of opening up the large area of land – one that has been a secure Navy base for years, Fritz said.

He added that he expects the department to have at least a simple analysis by early July, when there will be public hearings on the matter.

“We’re preparing ourselves for that,” Fritz said.

The DEP also is exploring what the price tag for the cleanup would be if the base is used for a much different purpose.

‘A Big Help’

A team of people from the department, including Commissioner Gina McCarthy, toured the base in late May and met with representatives from the Navy. Gov. M. Jodi Rell’s office arranged the visit.

“I have asked DEP Commissioner Gina McCarthy to form a special team go over every square inch of the base and make a thorough record of all contamination, waste storage locations and other such sites,” Rell said before the tour, in a prepared statement. “The Navy has been a presence in Groton for nearly 100 years. If they were ever to really leave, we would require them to make sure that 100 years of environmental effects have been fully addressed – and we need to know exactly how much that is going to cost, because that has to be figured into any savings calculation by BRAC.

“I am grateful to the base commander, Capt. Sean P. Sullivan, for allowing us the access we need. The Navy has also promised to give us copies of any records they have on remedial actions they have already taken or are planning. This should be a big help in our examination.”

The cost of any cleanup at the base will be a key issue in determining whether the Department of Defense will really see any savings by closing the base.

Earlier this month, an independent commission exploring the Pentagon’s recommendation to close the base finished a two-day visit to the base, according to the Associated Press. The group took a tour, questioned military officials and listened to the arguments of state and local officials.

Rell said commission members asked questions that signaled they understood the importance of the base.

“I feel like we fired the first salvo across the bow of the Defense Department,” Rell told the AP.

The Pentagon has recommended moving personnel and submarines from Groton to existing shipyards in Norfolk and Kings Bay.