Cavern Excavation & Ground Support
RIX excels at civil projects in areas of limited access or confined space, such as the North Head STP Mini Hydro Electric Project. Works were undertaken in a cavern 60m underground and below the access shaft, with materials, plant and equipment being dismantled and craned down a shaft to be re-built within the cavern.
There were four phases to the project:
Phase 1 – Staged excavation
Staged excavation of the roof and walls, including support consisting of rock bolts, meshing and shotcreting of the new turbine room.
Phase 2 – Gantry beam
Gantry beam construction and installation, where form and pour in-situ concrete reinforced gantry crane rail beams.
Phase 3 – Pipe and flange installation
Unable to turn the wastewater off completely, professional scuba divers cut out sections of the mainline pipe and weld from the inside.
Phase 4 – Concrete encasement
The valve and DOOS were concrete incased, and due to long pumping distances underground, the concrete was put to ‘sleep’ at the concrete plant and ‘re-actived’ when it reached its final position.
The project was successfully completed to program, safely and to the highest quality.