Design of a Flexible Stiff-Leg Mooring System, Transfer Bridges, and Foundations at McMurdo Station, Antarctica

McMurdo Station is the largest research station in Antarctica and is operated by the National Science Foundation. Climate change has significantly reduced the lifespan of reinforced floating ice piers that the station constructs for annual offload and resupply operations. A more robust replacement solution was required to meet the station’s long-term needs. A steel barge-like floating dock moored in position with stiff legs, overwintering in Winter Quarters Bay, was the preferred option. Two steel orthotropic-deck transfer bridges with box girders were designed as access points between the barge and the shore. The stiff-leg mooring system included flexible axial elastomeric elements (load cells) to secure the barge and limit displacements. Precast concrete stiff-leg foundations were designed to be assembled on-site by post-tensioning two pieces. Barge forces are transferred to slurried freeze-back piles installed in 70 ft (21.3 m) of fast ice. Special considerations were given to account for the harsh environment, an extremely remote location, maintenance considerations, limited on-site resources, equipment limitations, environmental contamination, and climate change.