NORTH ATTLEBORO - The town is expecting to receive more than a half-million dollars as the result of a settlement of a class-action lawsuit against major oil companies.

North Attleboro joined the lawsuit, along with about 80 other communities, alleging that a chemical used as a gasoline additive had seeped into drinking water supplies.

The chemical is methyl tertiary butyl ether - known as MtBE, an additive first put in gasoline during the 1980s in response to the Environmental Protection Agency's program to reduce air pollution.

Similar class action suits have been filed throughout the country alleging that oil companies used the additive, even though they knew MtBE could cause groundwater contamination if it leaked from underground storage tanks.

North Attleboro's wells tested for small amounts of the additive in 2001. The amount detected was far below the levels listed for concern in water safety guidelines, however. The town did not have to pay anything up front to join the lawsuit, which was handled in Massachusetts by the law firm Rodman, Rodman and Sandman, which worked in conjunction with attorneys in New York and Dallas.

The town's portion of the settlement actually amounted to $800,000 but will actually be closer to $530,000 after attorney's fees are subtracted.

Town Administrator Mark Fisher said the money will be placed in the water enterprise fund so that it can be used for the future protection of the town's wells.

He said the best part about the settlement is that the oil companies have accepted liability for the next 20 years.

"So, if our contaminations levels rise, they will have to come in to pay for the treatment to remove it," Fisher said.