Redcliffe Community Zone
With the completion of excavation and waterproofing works at Redcliffe Station, foucus had shifted to the construction of the station’s base slab. This involved installing steel reinforcement and pouring 5500 cubic metres of concrete.
Each of the nine pours required to construct the base slab took around seven hours to complete. Concrete was continuously supplied by up to 14 concrete trucks. Each truck made approximately eight trips over the course of the pour, delivering up to 650 cubic metres of concrete.
After an initial seven days of wet curing of each 1.5m deep section of the base slab, an additional 56 days were needed to complete the process. The last four of the pours are still in the final curing process and works are now underway to prepare for the arrival of the tunnel boring machines (TBMs) later this summer. This includes the removal of temporary struts to clear the way for the TBMs to pass through the station box unhindered. Also ongoing is the construction of the first section of temporary segment support blocks. These blocks will support the TBMs and their 130m long trailing gantries being maneuvered through the station box to where the cutterhead is to be lined up for the next section of tunnelling.
By the time the TBMs reach Redcliffe Station they will have constructed more than 1600 rings over approximately 2600m since departing Airport Central Station.
Dewatering and environmental testing
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 has been in place to ensure PFAS is not spread.
The 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. Dewatering is scheduled to be turned off by the end of the year.
Water levels are closely monitored and have remained within 1m of the recorded groundwater levels for the area.
To find out more, view the Redcliffe Station dewatering fact sheet.
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