A system for uncovering a desired and pre-planned trench. A trenching machine is equipped with sensors, including visual imaging sensors. The sensors detect the inclination of the ground and movement of the trenching machine, as well as the angle of a trenching boom. Using this information, and a pre-determined preferred trench grade, a processor commands the trenching boom to adjust its angle to maintain the preferred trench grade. Surface irregularities may therefore be accounted for along the length of the trench to maintain a constant grade at the trench bottom.