Casella Waste Systems Inc. is moving forward with plans to build a transfer station in Westbrook that could handle all of the trash that now goes to the Maine Energy Recovery Co. in Biddeford.

The transfer station is part of the latest plan, made public in April, for shutting down Casella’s unpopular MERC incinerator in Biddeford. But a company official said Monday that the developments in Westbrook don’t indicate the plant’s closure is imminent.

Building a transfer station in southern Maine has long been the company’s plan, regardless of what’s happening with MERC, said Joe Fusco, a vice president of Vermont-based Casella.

The company plans to begin construction within the next year on a 13,000-square-foot trash transfer station on County Road, Fusco said. The Westbrook Planning Board will review the site plan at a meeting at 7 tonight.

Casella announced in April that it planned to sell MERC to Biddeford and dismantle the incinerator, which residents blame for impeding development because of its odors, air pollution and truck traffic.

The plan called for the trash from 15 communities that’s now burned at the incinerator — about 285,000 tons in 2010 — to go instead to a yet-to-be-built transfer station in Westbrook, where it would be sorted and then hauled to the state-owned Juniper Ridge Landfill in Old Town.

Although Casella and Biddeford are still working out details of the plan, Fusco said, that’s no reason to stop moving forward with the transfer station.

“They’re not necessarily connected. … This is a longer-term planning activity,” he said.

Casella has owned the property on County Road in Westbrook for more than a decade, and once planned to build a facility for construction and demolition debris there.

The plan for the site has changed several times over the years. The site was most recently permitted for a trash-processing facility, where Casella planned to take in trash and turn it into fuel pellets that would be burned at the incinerator in Biddeford.

The plan, which would have reduced truck traffic and pollution in downtown Biddeford, fell apart because of a conflict among Casella and Biddeford officials.

Westbrook City Planner Molly Just said the main change in Casella’s latest site plan is removing the trash-processing facility.

Casella, which now uses “third-party transfer stations” in southern Maine, has always felt that it would make business sense to have its own transfer station in the area, said Fusco.

Plans to build one were made “much before anyone was considering selling or buying Maine Energy,” he said.

Fusco said he didn’t know when construction would be completed on the Westbrook transfer station, which could handle 1,000 tons of trash per day.

Meanwhile, negotiations for Biddeford to buy the incinerator continue, said Mayor Alan Casavant.

The plan announced in April hinged on Casella, which operates Juniper Ridge, taking ownership of the landfill from the state so it could take out-of-state trash, which a state-owned landfill cannot do.

The plan hit a roadblock when a bill to allow the transfer of ownership was killed by the Legislature. Casella and Biddeford officials vowed to continue to work toward shutting down the incinerator.

Casavant said company and city officials will likely meet in the next week or two to discuss the terms of their purchase-and-sale agreement. “We’re inching along,” he said.

The agreement initially was for Biddeford to buy the plant for $7.5 million and pay for it through inflated disposal fees and revenue from a tax-increment financing district and cellphone towers on the incinerator property.

Casavant said “there have been changes” since then, but he refused to say what they are.

He said he is still “very optimistic” that the city and Casella will reach an agreement, but “who knows when or who knows what?”

Staff Writer Leslie Bridgers can be contacted at 791-6364 or at: lbridgers@pressherald.com