Project Overview
Mundaring Weir is a dam (and historically the adjoining locality) located 39 kms from Perth, Western Australia in the Darling Scarp region.The dam and reservoir form the boundary between the suburbs of Reservoir and Sawyers Valley and the dam impounds the Helena River.
The Irish Australian engineer C. Y. O’Connor was involved in the design of a scheme that transported water to the Eastern Goldfields of Coolgardie and Kalgoorlie in the eastern part of Western Australia. The weir was completed in 1903. Considered to be one of Australia’s greatest engineering achievements, the scheme pipeline still supplies drinking water to 100,000 people from Mundaring to Kalgoorlie today.
In 2017, Clough was engaged for the Mundaring Weir outlet works upgrade with the aim to install new inlets into the intake tower so that water could continue to be drawn from the dam during periods of lower water levels. The project included the upgrade and refurbishment of the existing intake tower and outlet structures including installation of a 43m x 2.5m sleeve into the intake tower, instalation of inlet and refurbishment of control gates.
MMA's scope on this project was to support Clough with technical grouting services to re-sleeve the heavily corroded inlets.
MMA's Solution
MMA developed the grouting procedure and selected the plant and equipment to perform the works, developed the grout mix design and conducted a full-scale trial in our Henderson facility. We also supplied the grout, sealing systems, batch plant and pumping spread.
Technical Details
The designed grout mix was a mix of potable water and general-purpose cement with a SG of 1.92 and minimum characteristic compressive strength of 50MPa at 28 days.
The existing cast iron collar was cleaned before steel inlet inserts were installed. We modified the insert sleeves to allow its neoprene grout packer to be activated from the external face of the insert. By tightening bolts on a temporary flange, a seal was activated followed by the grouting of the grout packer.
Outcome
MMA developed a sealing system that enabled the divers to rapidly install and seal the intake sleeves and achieve 100% seal against the existing, corroded cast iron inlets without any leaks or failures. Diver bottom time was heavily restricted due to the water depth and the critical nature of the work to Perth’s water supply meant that the sealing systems and grout injection had to work the first time round – there was no room for error.
Following the successful completion of the project, the intake tower is back to supplying water to Perth and the Goldfields as it has done for the past 120 years.
Key Equipment
- SGM 2000
- Propietry grout seals