An open house and big truck expo will be held from 10 a.m. to noon Saturday at the city of Urbandale’s newly completed parks and public works maintenance facility at 9401 Hickman Road. The $26 million, 150,000-square-foot facility includes a nearly 3-acre rooftop. The building was designed with many energy-efficient features, including a 4,000-gallon rain barrel that captures rain from the roof. The captured water is then reused in Urbandale’s parks to water flowers, shrubs and trees. A short presentation begins at 10:30 a.m. and will be followed by guided tours of the facility, a big truck exhibit, light refreshments and activities for families and kids. The public is invited to attend the free event.