Sydney Ports Corporation completed in 2013 the construction of the new Bulk Liquids Berth (BLB2) at Port Botany, NSW. (The BLB2 LP was transferred to NSW Ports on 1 June 2013 as part of the 99 year lease for Port Botany and Port Kembla). The berth construction included the installation of 136 large diameter driven piles adjacent to an underground Liquid Petroleum storage facility. The underground facility comprises four large caverns excavated into the Hawkesbury Sandstone bedrock 130 metres below surface level. To ensure the long term integrity of the storage cavern strict vibration limits were set as part of the conditions of approval for the BLB2 piling operations. Dynamic analysis using Plaxis 2D was undertaken, indicating that the proposed piling was feasible within vibration limits.
A pile vibration management plan was developed in conjunction with all stakeholders, and a monitoring system installed. The piles were driven to target depths using both vibrating and impact hammer. Piling was staged with the furthest piles from the cavern being driven first, with works proceeding towards the cavern so that construction methodologies could be adjusted if the vibration limits were being approached. Vibration monitoring confirmed that the vibration limit criteria applied to the LP storage cavern were not exceeded by the piling, and that the vibration levels recorded were of the same order of magnitude as predicted in the analysis.