Salem — The Planning and Zoning Commission Tuesday night unanimously approved relocating a water-treatment facility at the Salem Four Corners shopping plaza.

The vote to move the facility from the basement of a nail spa to a new building behind the plaza advances the state Department of Transportation's plan to build a roundabout at the site. Relocating the facility, which treats water for the plaza, is part of the DOT's overall plan for the intersection.

Town and state officials say that a roundabout could ease traffic issues at the busy site, which is the intersection of routes 82 and 85.

The DOT's site plan still needs approval from the state departments of Environmental Protection and Public Health.

The DOT is in the final design stage for the roundabout. Preliminary plans call for the intersection of routes 82 and 85 to be moved northwest of where it is now. The traffic signal would be replaced by a modern roundabout with crosswalks for pedestrians and improved entrances into businesses.

Construction of the $4.5 million federally funded project is scheduled to begin April 2012, with the roundabout completed that summer. The final aspects of the project, such as landscaping, might be finished the following summer.

The next step in the project is to demolish three buildings that the DOT recently bought in the area for $600,000. Scott Bushee, DOT project engineer, said demolition is scheduled for the spring.

"This is a very important safety upgrade for our community," said First Selectman Kevin Lyden.

a.renczkowski@theday.com