Redcliffe Community Zone
Diaphragm walls for the underground station were completed in late 2017. Excavation is now underway to remove soil within the station box, with 7500 cubic metres of soil removed to date.
With excavation below the water table, a process called dewatering is required to temporarily lower the groundwater level within the work site. Dewatering involves temporary and localised lowering of the groundwater level, by pumping from purpose built bores, to allow deep excavations to occur without the work site refilling with water. This process is being used at the Redcliffe Station site to enable construction of the underground structure which forms the station. To find out more, view the Redcliffe Station dewatering fact sheet.
Through routine environmental investigations for the construction of Redcliffe Station, the Public Transport Authority (PTA) has discovered perfluoroalkyl and polyfluoroalkyl substances (PFAS) in the groundwater. PFAS are manufactured compounds that have been used in certain types of firefighting foams and a range of consumer products, including non-stick cookware, fabric treatments, furniture and carpet stain protection, and food packaging since the 1950s. Environmental contamination by PFAS is an emerging challenge worldwide, and in WA is starting to be reported at various sites.
PTA has reported the results from the project’s environmental testing to the Department of Water and Environmental Regulation (DWER), the state regulatory agency. The presence of PFAS at the site has not been caused by the Forrestfield-Airport Link project and during the dewatering process, a strict management and monitoring regime will be in place to ensure PFAS is not spread.
The six-month dewatering program began in February 2018, with the target level reached in March. Three of the six dewatering wells installed are currently in operation, with the water pumped into four reinjection bores outside the station box.
Water levels are closely monitored and have remained within 1m of the recorded groundwater levels for the area. Dewatering will be ongoing until late August.
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