A utility trenching and sidewalk system comprising modular utility sidewalk units which may be assembled together to form a cable trench. The modular units are formed from plastic composite material and include sidewalls, a bottom wall and covers which define a chamber for housing utility cables. A cavity formed in the sidewalls and bottom wall is filled with concrete through apertures in the sidewalls. The covers are removable from the module to provide access to the chamber. The module further includes a recess for receiving a paving material which serves as a sidewalk surface in the installed system.