2018 – Refurbishment of the 120 year old inlet tower on Mundaring Weir

Alex Gower, Neil Johnson, Bob Wark

This paper provides an outline of the design and construction of the works undertaken to refurbish the 120 year old intake tower at Mundaring Weir. The project drivers included asset condition, hydraulic capacity, reduction in unusable storage, and reduction in evaporation from the reservoir. The one off sale of this water together with the present value of the reduction in evaporation pays for the project construction and is a significant response to climate change that is taking place in the region. The effects of Alkali Aggregate Reaction (AAR) compromised the efficacy of the Intake Tower operating as a dry-well, while the small diameter and significant corrosion of cast iron pipes and valves had severely diminished the service capacity of the structure. The solution implemented in this project included: lining the Intake Tower with a 37 m long by 2.7 m diameter 316 stainless steel liner; construction of a new inlet 15 m below the reservoir surface using a bespoke underwater coring rig; relining of existing pipes through the dam wall; and new outlet control pipework and valves downstream of the dam.

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