115 kV Underground Cable System






O&G was the civil contractor for this project which included installation of 10 miles of underground conduit with three runs of cable and six riser structures. Up to eight crews worked simultaneously, both day and night, while traffic flow was maintained, and over 280 existing utilities were worked around during the course of the project. Once underlying utilities were located, the existing State and local roadways were sawcut and 3’ wide by 5’ deep trenches were excavated. Shoring was then erected and conduit was installed and encased in concrete. Thermal flowable fill was placed and temporary hot mix asphalt installed for the roadway surface. As part of the conduit system, 28 large splicing vaults were installed along with numerous smaller fiber optic hand holes. At the ends of the underground runs, six large caissons were excavated for the riser structure foundations. A “jack and bore technique,” directional boring, to tunnel under Metro-North Railroad in Norwalk was utilized. Subsequent to conduit completion, a full depth restoration of the roadway trench was performed including full lane milling and paving.

115 kV Underground Cable System in Connecticut