Construction of a new Walmart Supercenter just east of County Line Road is progressing ahead of schedule and could open this fall.

Following a groundbreaking in September, officials said the new store, the third within a 23-mile radius, would be open by spring 2013. Madison has a Walmart Supercenter at 8650 Madison Boulevard, while Athens’ store is also on U.S. 72.

The 180,000-square-foot Supercenter is expected to employ 350 people.

“We’re just happy to be bringing a Walmart to the Huntsville area,” said Ken Marshall, executive vice president with Birmingham-based Colonial Properties Trust. “We really feel like it will serve the continued growth of Madison and Huntsville as it expands further to the west.”

The store, part of a 53-acre development, will be built in three phases. The first phase will include the Supercenter and 90,000 square feet of additional commercial space for retail and restaurants.

Phase 2 will consist of 80,000 square feet of commercial space, while Phase 3 includes a 27-acre multifamily residential development.

Marshall said Colonial Properties Trust is “working actively” to line up tenants for the remaining retail parcels. He said the group is talking with businesses who generally like to be located near a Walmart.

“A lot of those tenants would be service oriented businesses like hair salons, nail salons, restaurants, cafes and things like that,” he said. “We’ve got several people we are negotiating agreements with, so in the next couple of months we should have a better idea.”

The new retail center will be a short distance from the Shoppes of Madison, located just east of the new Madison Hospital. Most of the tenants in that development have opened, though work continues on a Panera Bread and a Ross.

“Retailers generally like to be in an area where other retailers are,” Marshall said when asked about competition between the two developments. “It creates that critical mass in creating a variety of shopping opportunities for the customer making multiple stops in one area.”

Total construction costs on the project are estimated at $60 million, while annual sales from the retail center are expected to exceed $70 million.

The project also includes $2 million of public roadway infrastructure, including the widening of U.S. 72, and construction of a new road called Promenade Point Parkway.

Traffic signals will also be installed at the intersection of the new parkway and U.S. 72. A call made to Huntsville’s planning department regarding the status of the infrastructure improvements was not immediately returned.