THOMASTON, Maine — Customers filled the new Walmart Supercenter moments after the grand opening ceremonies were completed Wednesday morning.

The opening of the 150,000-square-foot building — which is expected to employ 300 people — was welcomed by local officials.

“Welcome Wal-Mart,” Thomaston Town Manager Valmore Blastow shouted out as he took the podium to speak in front of the store and more than 100 people who had gathered. “We have been pursuing this day for 13 years.”

The town manager recalled how a Wal-Mart representative came to his office in April 2000 and inquired about the possibility of opening such a store in Thomaston. Before that could occur, however, he said city and state officials had to work together on a $3 million sewer extension to reach that section of Route 1.

He credited the effort of former Selectman Walter Breen who conducted an informal survey at his regular eating place — the former Dave’s Restaurant — and found there was support for Wal-Mart coming to town.

Jamie Logan, an account executive for the Maine Department of Economic and Community Development, said the new store was a win-win situation for all of Knox County. The opening of the Thomaston store coincided with the closure Tuesday night of the 94,000-square-foot Walmart store in neighboring Rockland. But the new store, Logan said, adds 85 jobs and 50,000 square feet of additional retail space.

Store Manager Shawn Ames cited the company’s contributions to the community and highlighted another $8,000 in donations that morning to organizations, including to LifeFlight of Maine, local fire and police departments, and local schools.

The old store in Rockland had been built in 1993. Then in late 1999, Wal-Mart proposed building a Supercenter complex in Rockland across from its existing Walmart on property where The Home Depot later built a store. That was met with considerable public opposition and an advisory referendum was to be held in June 2000 when the company announced it was withdrawing its plan.

With the departure of Wal-Mart from Rockland, another company is ready to fill the void.

Ocean State Job Lot continues with its plan to move into the space by spring, according to Ocean State Director of Marketing David Sarlitto. The company plans to lease out a portion of the building.

“Our target move-in time period is spring 2014. Needless to say, we’re excited to be expanding our presence in Maine,” Sarlitto said Tuesday.

Ocean State’s Maine stores are in Bangor, Belfast, Oxford and Sanford.

The company expects to employ 30-40 people.