The Proposed Strait of Belle Isle Cable Crossing

Abstract

The Muskrat Falls Hydroelectric Project will allow Newfoundland and Labrador to reduce greenhouse gas emissions created by oil-fired, electricity generation by more than one million tonnes annually [1]. In order for the hydroelectricity created at Muskrat Falls to be consumed by people on the island of Newfoundland it must be transmitted across the Strait of Belle Isle. The Strait of Belle Isle is approximately 14.5km wide at its narrowest point and poses many engineering challenges for installing a subsea transmission cable. Tides, currents, bathymetry, icebergs and sea ice are just some of the ocean related environmental factors which create problems while planning for a subsea cable crossing in the Strait of Belle Isle. Investigations have been conducted to study each of these factors and engineers have devised a plan to install three subsea cables across the Strait. Three horizontal directional drill paths will be drilled from each shoreline between. The boreholes will extend between 1.5 and 2.5km into the Strait. At about 65m below the water’s surface the drill paths will pierce the seabed. A transmission cable will be placed in each of the drill paths. Between the two sets of drill paths, the cable will be laid directly on the seafloor. The cable will follow the natural occurring bathymetry and be laid in the deepest areas. Once the cables are in place a rock berm will be placed around each cable [2]. Although installing a subsea transmission cable is not a new task, there are currently no subsea transmission cables in the world that had to be designed around such unpredictable ice conditions. Based on this fact and based on the evidence outlined in this paper, the proposed plan for the for the Strait of Belle Isle cable crossing seems to leave the transmission cables at unnecessary risk of damage.