Iceberg Risk Analysis for Strait of Belle Isle Cable Crossing

Abstract

Abstract In 2016 Nalcor Energy installed subsea cables across the Strait of Belle Isle, which comprises part of the Lower Churchill Transmission Project linking Muskrat Falls, Labrador, and Soldier's Pond, Newfoundland. The cable crossing site is southwest of a shoal which filters out deeper draft icebergs which could potentially contact and damage the cable. An initial study in 2011 was followed by iceberg tracking and current monitoring programs at the cable crossing site and a final study incorporating these data 2015-2016. This paper describes the application of a drift-based Monte Carlo model to assess iceberg risk to cables laid on the seabed in the Strait of Belle Isle. The model considers the effect of iceberg rolling which could potentially result in icebergs increasing draft and contacting cables laid on the seabed. Modeled iceberg drift was based on field observations, and measured and modeled currents. Based on results from the 2011 analysis it was decided to use directional drilling to route the initial portions of the cable from shore to break-put locations on the seabed in water depths in excess of 70 m. Rock dumping is used to stabilize the cables on the seabed at deeper water depths. Due to the extreme difficulties in trenching the very strong seabed or tunneling across the Strait of Belle Isle, the selected solution offers the most technically feasible and cost-effective solution for cable routing across the Strait of Belle Isle.