A system for uncovering a trench. The system comprises several subsystems, including a work machine and a frame for providing a seal with the surface to be trenched with a saw blade contained therein. The blade is supported on a hub which is slidably movable relative to the frame by operation of a linear actuator, which may be a hydraulic cylinder or the like. The vertical location of the blade within the frame is continuously adjustable to create a deeper or shallower trench. A monitoring system is provided to monitor the vertical location from an operator station.