2004 – Remedial Works on Australia’s Oldest Embankment Dam

P J Cummins, G S N Adikari, C Hill and A K Parkin

Yan Yean Dam has been a key component of water supply to the City of Melbourne since its completion in 1857. Of typical puddle core construction over deep alluvium, it has performed well over the years since, with the exception of the discovery of a piping tunnel in 1949, duly repaired with minimal risk. However, in the absence of an engineered filter, some potential for recurrence has remained, and this, coupled with a continuing outward creep of the downstream batter and the need to ensure compliance with current design practice, has driven the recent remedial program.

The original embankment was 9.6m high and almost a kilometer long, with 3:1 and 2:1 batters and a wide core, now modified by the placement of a 3-component full-height chimney filter and stabilising fill. Critical issues in the design of these remedial works are described herein, including foundation preparation, the evolution of the design slope, the cellular filter and its specification, and measures required for the preservation of historic structures. Because of the potential impact on public parkland and nearby housing, community consultation was a vital input that enabled good relationships to be maintained throughout the project.