Town officials had warned that the costs to remove two underground fuel tanks at the Department of Public Works garage could increase, if contamination was found.

Turns out, they were right.

Public Works Director Joseph Michelangelo came to the Board of Selectmen's Wednesday meeting to ask that a bonding resolution for a variety of municipal projects that was passed last March be increased by $218,500 to accommodate the extra costs. The selectmen approved the amendment unanimously.

Michelangelo said that original cost estimates for the tank-removal project included $30,000 for remediation and $163,000 for new, above-ground tanks and pumping system. However, the lowest bid for the new tank system came in at $203,000, adding to the costs was contamination from diesel and oil that was found in a 300-foot radius around the old tanks.

Cleaning up the contamination, Michelangelo said, will not be simple and may end up being a five- to 10-year process. He said it is believed the contamination came not from the 30-plus-year-old tanks currently in the ground, but from tanks that were buried in that spot before them.

While simply removing all the contaminated soil would be a quicker process, he told the board, it would also be the most costly option.

Instead, Michelangelo said, a process will be used that injects air bubbles into the ground and then removes the contaminants from that air.

"We may only need a half-dozen injectors or we may need 12 injection points," he said. "That will be determined by future testing."

Michelangelo also explained that the time the town will have to monitor the remediation is unknown at this time. If, for example, the ground was found to be clean after five years, he said, "We're done and out of the remediation business."

Because of the age of the underground tanks, state statutes require that they be removed or the town can face fines that Michelangelo said could end up costing more than the project itself.

Selectman Kevin Kiley pointed out the town had funded the tank-removal project before "we ran into obstacles," and wanted to know if that is being taken into consideration by the state as far as the threat of fines is concerned.

"They understand that," Michelangelo said.