PORTLAND – L.L. Bean is embarking on the largest expansion project in its 94-year history with plans to open at least five new stores in the Northeast and expand its retail space and distribution center in Freeport.

The plans will build on the company’s strategy to expand its retail operations, while enhancing its presence in Freeport, where it has its headquarters and flagship store, company officials said Tuesday.

The total cost has not been determined, but will amount to tens of millions of dollars.

“When you look at everything in aggregate, it’s safe to say this is the biggest project Bean has undertaken,” said company spokesman Rich Donaldson.

The move is the latest in a series of growth initiatives at Bean, which has enjoyed strong growth the past few years after a decade of flat revenues. Besides aiming to open more retail stores, the company has expanded its advertising and recently hired a new ad agency with significant Internet experience.

The first new store will open in September in Burlington, Mass., with another slated to open in October in Center Valley, Pa., near Allentown. A South Windsor, Conn., store will open in the summer of 2007.

The company is scouting other sites, with at least two stores planned in Greater Boston in 2007 and 2008 and others in undetermined locations in the years ahead. Besides its 120,000-square-foot flagship store in Freeport, L.L. Bean has retail stores in Virginia, Maryland, New Jersey and New Hampshire, as well as 14 factory stores in the Northeast.

“We’ll continue to look at the Northeast, and from our perspective any location from Maine to our store in Virginia is open to consideration,” Donaldson said.

In Freeport, the company plans to take a now-empty 16,000-square-foot building it owns next to its flagship store, renovate it and open it as retail space to sell a yet-to-be-determined product line.

Also on the drawing boards are plans for a development where a dirt parking lot and Bean’s factory store now sit across the street from the flagship store.

The development would include a parking garage with hundreds of spaces. Attached to the parking garage, and possibly on top of it, L.L. Bean plans to build up to 100,000 square feet of retail space that will be leased to other companies and could include several stores.

The company is seeking a development company to work in partnership on the project, Donaldson said.

A third component of the Freeport plans is a $35 million, 330,000-square-foot expansion to the company’s distribution center, located a couple of miles from the store. Construction began last month, with completion set for the fall of 2007.

The plant expansion will support the company’s growing retail operations as well as the increasing number of consumer orders over the Internet, by phone and by mail.

Chris McCormick, company president and CEO, said the plans represent a “major transformation” for downtown Freeport.

“These changes will significantly enhance the overall experience for L.L. Bean customers and represent tens of millions of dollars of new commercial investment in our hometown of Freeport,” he said.