Depressurisation Of The Cleveland St Underpass

Between May and July 2014 the Cleveland St Underpass on the Eastern Distributor, Sydney was successfully resurfaced using open grade asphalt some 15 years after motorway construction. To undertake this work required temporary depressurisation of the surrounding aquifer so that the motorway could be kept dry throughout the work period. Key to the project was rapid depressurisation such that works could be completed during night shift and within tight work hours dictated by RMS minimising disruption to one of Sydney’s busiest motorways. Surface monitoring of groundwater levels was also required to ensure the drawdown beneath adjacent structures was within acceptable limits established from review of construction records and historical data. The successful depressurisation of this section of the motorway was the culmination of 4 years of research, modelling, testing, permitting and monitoring. This paper describes the staged approach performed over 4 phases of investigation, testing and monitoring of the novel solution to dewatering that was utilised to make resurfacing possible.