In a 14 month $21m contract, it is being built by main contractor Utility Services, an alliance between South East Water, Thiess Services, Siemens and MWH. The ‘first dig’ of the detention tank started in early June and is expected to take two months to excavate.
Utilising diaphragm wall technology to build both the pump station’s pump well shaft and detention tank superstructure, sub contractor Piling Contractors will be using a Liebherr HS885HD crawler crane to excavate diaphragm walls. With a 12.5 m diameter, a final base depth of 13.5 m will be constructed.
Piling Contractors is also using a second large crane on the pump station job, a new Liebherr LR1130 lattice boom crawler model, hired from Alfasi Hire in Melbourne. It was delivered on eight semi-trailers, with Liebherr Australia engineers erecting and commissioning it.
Gravity fed facility
The inlet gravity sewer will feature 3m diameter manholes and 1.28m and 960mm diameter Hobas GRP pipes - shipped from Germany - to be installed by Crib Civil and TCG utilising open cut and hybrid micro-tunnel/auger jacking technology to a depth of 8 m.
Ground conditions feature stiff clays on the surface underlain by a thick sand layer containing artesian ground water. According to a spokesman for the contractor, the aquifer would have been difficult to control had they opted for conventional excavation methods.
The diaphragm wall will cut through the aquifer layer to the stiff sand and prevent any ingress of ground water into the works area. The contractor opted for diaphragm wall technology for its ability to reduce traditional construction methods by at least 50% ensuring reduced cost and time savings.
By completion of construction more than 3000m³ of structural concrete will have been placed together with 500t of reinforcement steel.
