Geotechnical Aspects Of Dredging And Reclamation Works For The Port Botany Expansion Project

This paper contains a discussion of the geotechnical aspects of the dredging and reclamation design and construction for the Port Botany Expansion (PBE) project in Sydney, Australia. The project involved dredging approximately 11Mm3 of Botany Bay Sands to form the 63 Hectare (Ha) reclamation. Dredging and reclamation works for the project commenced in 2008 and were completed in 2010. The bulk dredging works were carried out using cutter section dredges and various reclamation techniques were used including land discharge (pipelines), spreader pontoon and aerial discharge (rainbow).

This paper examines the dredging work completed at PBE from a geotechnical viewpoint and describes issues faced during design and construction, including methods for identifying suitable source dredging material, practical dredging tolerances, design of disposal areas for unsuitable materials and stability of underwater cuts and fill slopes.

The paper also discusses the specification for ground improvement works completed for the reclamation, including the earthworks testing requirements and fill verification processes adopted. The potential for fines being included in the reclamation was a major risk to future performance of the reclamation and so the methods used to assess and mitigate this potential risk are discussed. The results obtained from different compaction techniques including dynamic compaction, vibrocompaction and impact roller compaction are also presented in the paper.