A ground-level access operating system for a tank trailer. The ground-level system includes a cleaning/washing device, a venting device, an inspection access port, and device for loading/unloading the compartments. All devices in this system are located on the side of the semi-trailer, within an operator's reach on the ground. The devices locations are meant to be reachable to ensure operator safety. The operator of the trailer can execute all work without having to reach the top of the tank. Both of venting and cleaning/washing devices have their access port on top of the tank but are hooked up at a position proximate ground level, for an easy-to-reach operation and inspection by on operator on the ground.