Local geology was extremely complex with highly altered sediments and corestones which created challenges when operating the jack up and deciding the appropriate pile installation method. Conventional reverse circulation drill techniques would have been risky so a bespoke hammer drill system was designed and built. There were also environmental concerns as the Island is surrounded by the world’s 2nd largest barrier reef and a closed loop drilling mud slurry system was installed for management of the spoil.
The 914mm diameter rock socketed piles, ranging from 16m - 48m, provided foundation support for two finger wharfs with approach jetties forming an integral part of the new port facilities for the massive Nickel Development Project. The 102 piles were installed singularly in rows and the 24 rock socketed rakers in clusters to accommodate an ultimate compressive load of 1130t and tensile load of 835t respectively. All 24 of the rakers needed a drilled socket in order to attain the tensile capacity requirement. The vertical piles required drilling if refusal occurred before the minimum embedment level was attained. The piles were interlinked with precast concrete crosshead beams, which were spanned with precast concrete deck panels and overlaid with a final in-situ concrete deck slab.