HAMPDEN (AP) – The Pine Tree Landfill, a 200-foot mountain of trash that’s a familiar landmark to motorists along Interstate 95, will become Maine’s first dump site to generate power from methane gas.

Landfill owners will break ground May 14 for the state’s first power plant that converts gas that results from rotting rubbish into electricity. Once the 3-megawatt plant is operating later this year, the $6 million system will generate enough energy to light about 3,000 homes for 15 years.

In addition, waste heat from the turbines has the potential to dry lumber or grow vegetables.

The Hampden project is tied to a second project at the state-owned Juniper Ridge Landfill in Old Town. A planned power project there could light more than 15,000 homes for up to 60 years. It would use engines retired from the Pine Tree Landfill.

Both landfills are operated by Casella Waste Systems Inc. And both methane projects reflect a national effort to capture the gas from solid waste landfills and produce homegrown energy and fight global climate change. New federal tax credits helped to make it profitable for Casella and other waste firms to get into the power business.

“Our landfills aren’t that large,” said David Burns, who monitors landfill gas activity at the Maine Department of Environmental Protection. “There hasn’t been enough gas production to make them worthwhile, and the incentives haven’t been there. That’s all changing.”

Burns believes that at least four other landfills scattered around Maine are candidates to produce energy from methane. Nationally, 400 operating or recently closed landfills have methane power plants, and the U.S. Environmental Protection Agency estimates that 560 additional landfills have the potential to produce enough electricity for hundreds of thousands of homes.

Casella, which owns Pine Tree and operates Juniper Ridge for the state, also owns the Maine Energy trash-to-electricity plant in Biddeford and has two landfill gas plants in New York and Vermont.

Pine Tree Landfill first starting burying waste from the Bangor area in 1975 and now holds 6 million cubic yards. The 42-acre site is set to close by 2010.

A 50-foot high flame now shoots from a flare into the sky from the site, burning off methane gas that’s just going to waste. That gas will be captured when the new power system is built.