Collie River Gauging Weir
Due to the ability to reduce the river flow for only 3 weeks, the design and construction methodology included precast concrete panels and footings around the perimeter of the weir to create a 32m long by 2.5m wide by 1.2m deep weir structure.
The weir design included internal steel beams with mass concrete poured around, and a below ground cut-off concrete wall under the weir.
The weir was constructed by installing the concrete cut off wall which was 1m deep under the weir. Precast concrete footings were then installed to support the concrete panels around the perimeter of the weir. Steel beams provided support between the concrete panels and then concrete was poured between the panels creating a “box” structure.
The top surface of the weir was then poured with 40 MPa concrete to provide a smooth surface for the water flow.
The area downstream of the weir was constructed as a stilling basin and the river bank was reinstated with geofabric and rock bank protection.
Serpentine River Gauging Weir
The weir was required to span across Serpentine River for a width of 25m. The weir consisted of a cutoff wall underneath the weir, and a 25m long by 1.6m wide concrete structure with a “V” notch to direct the water flows for gauge measuring.
Downstream of the weir, a 6m by 5m concrete stilling basin was designed to capture and dissipate the lower flows, as well as mortared stone pitching along the river banks surrounding the stilling basin and downstream of the weir.
Design, Construction Methodology and Technical Specifications for construction