THOMASTON, Maine — Construction for the Walmart Supercenter is expected to begin by the end of the month, according to a company spokesman.

The approved 150,000-square-foot retail complex should be open by early fall 2013, according to William Wertz, director of community and media relations east for Wal-Mart.

The commercial development has been in the planning stages for several years. The company received its final government permits this spring and summer. Less than a month ago, the company provided an environmental easement to the the Maine Department of Environmental Protection as a safeguard since part of the 30-plus acres on which the project is being built was a former junkyard.