Wallace Group, a San Luis Obispo-based engineering firm, is gearing up to begin work on a half-million-dollar contract with the city of Atascadero to redesign the Highway 101 interchange at Del Rio Road, the company recently announced.

The contract includes the planning and design work for three roundabouts, including two at the highway interchange and another at Del Rio Road and El Camino Real.

The contract, inked in December, allows for expenditures up to $562,400 for design changes to the overpass to better handle the area’s traffic for the planned construction of a Walmart store.

A construction date for the new Walmart has not yet been set because the project is currently tied up in a lawsuit with local citizens group Save Atascadero.

However, city officials are going forward with preparations for the project as planned.

Other services Wallace Group is tasked with include transportation planning, design analysis, plans, reports, preliminary construction cost estimates, drainage and associated environmental services as needed to obtain Caltrans approval, according to the city.

Wallace Group, one of three firms interviewed for the position late last year, has completed similar projects including designing Goleta’s first roundabout at the Los Carneros and Calle Real intersection, in place since November 2012.