A trailer assembly has a frame, wheels attached to and bearing the frame and a hopper mounted on the frame. A front conveyor belt is mounted in a front part of the hopper and is operable to rearwardly convey contents of the hopper overlying the belt. A rear conveyor belt is mounted in a rear part of the hopper and is operable in a first mode to rearwardly convey contents of the hopper overlying the rear belt and is operable in a second mode to forwardly convey contents of the hopper overlying the second conveyor belt. Depending on the direction of conveyance of the rear conveyor belt, the two conveyor belts can be operated either to convey contents for dumping through a rear gate or to convey contents for dumping through a bottom gate.