A site plan for major modifications of the Walnut Creek YMCA will be presented to the West Des Moines Plan and Zoning Commission tonight.

The plan shows a 4,200-square-foot addition to the existing Y that will house locker rooms, a swimming pool mechanical room and a bicycle spinning classroom. The site plan also shows 35 additional parking spaces.

Walnut Creek YMCA Executive Director Terry Feldt said construction will begin as soon as the project is approved by the city. The addition will cost $2.3 million.