A mechanized unit that is moved through a trench in the ground for the purpose of placing a length or lengths of a utility or utilities by a guide device on the bottom of the trench, and then encasing the placed utility or utilities. The unit has at least one plow to sweep the material excavated from the ground to form the trench back into the trench onto a screening member mounted to the movable unit. The screening unit has sections of progressively larger openings from front to rear. The screening member preferably is vibrated to deposit onto the one or more utilities layers of the excavated material having particles of progressively larger size from the bottom toward the top of the trench to protect the utility or utilities from physical damage caused by larger excavated particles.