Champlain Hudson Power Express Terrestrial Project Trenchless Crossing

The Champlain Hudson Power Express project involved installing a pair of HVDC electrical transmission cables with an associated telecommunications line from Canada to New York City, NY. This work includes approximately 126 crossings under roads, railroads, wetlands water bodies, and obstructions to be installed using horizontal directional drilling (HDD) methods to minimize interference with use or impacts to the surface environment. The new transmission line will be approximately 146 miles in length, extending from the south end of Lake Champlain to Astoria, NY, following the Hudson River Valley of New York.

The underground construction of two HVDC electrical transmission cables will be housed in individual 10-inch-diameter plastic conduit spaced approximately 15 feet apart. A third, minimum 2-inch-diameter plastic conduit will be bundled with one of the 10-inch diameter conduits for a telecommunications line. The cable duct will be installed at least 25 feet below congested areas, roads, railroads, under/around other obstructions, 15 to 25 feet below wetland, and 35 to 45 feet below open bodies of water using HDD methods.

Brierley Associates was contracted to provide review of the existing geological and geotechnical conditions for each HDD crossing, provide a descriptive narrative of the HDD crossings in support of the design drawings and technical specifications, present pipe stress and annular pressure analyses that support the proposed designs and supporting calculation packages, and analyze construction considerations including inadvertent return mitigation.