what to do with luggage when tour at Jiayuguan

Our train will reach Jiayuguan South at 11am. We plan to tour Jiayuguan by hiring a driver at the station, then catch the train at 6:30pm to Dunhuang. Is it generally safe to leave our luggage bags with the driver in the car? Or is there a luggage service at Jiayuguan South station? where and how much? Thanks.