Facility layouts and configurations for an automated crop production system for controlled environment agriculture. In particular implementations, the core of the facility comprises a controlled growth environment and a central processing system. The controlled growth environment includes systems for exposing crops housed in modules, such as grow towers, to controlled environmental conditions. The central processing system may include various stations and functionality both for preparing crop-bearing modules to be inserted in the controlled growth environment, for harvesting crops from the crop-bearing modules after they have been extracted from the controlled growth environment, and for cleaning or washing crop-bearing modules for re-use. The controlled growth environment may include vertical farming structure having vertical grow towers and associated conveyance mechanisms for moving the vertical grow towers along one or more grow lines. The conveyance mechanisms may include a return transfer mechanism that creates a return or u-shaped path for each grow line.