2023 – Briseis Reloaded: The Renaissance of Derby and the Implications for a Small Portfolio Dam Owner

Josh Clark, David Stewart, Karl Velasco, Kosta Tsourdalakis

Recent flood inundation studies of Cascade Dam, located on the same site as the failed Briseis Dam upstream of the township of Derby, Tasmania, provide a unique opportunity to validate outputs from modern 2-Dimensional flood inundation analysis against the true impacts of Australia’s most tragic dam failure event. The renaissance of the valley downstream of the dam due to the establishment of the “Blue Derby” mountain biking destination has resulted in a rapid increase in Population At Risk, comparable to the 1929 tin mining community. This provides new challenges to the current dam owner as the impacts of Consequence Creep, inequitable investment between downstream development and the dam, and standards-based engineering requirements are comprehended. Small portfolio dam owners are particularly exposed to standards-based engineering requirements, with high regulatory accountability contrasted by marginal funding streams. This is compounded by the limited internal resourcing capacity to enable risk-informed dam safety positions to be evaluated and reviewed on a sufficient basis. This paper is a case study supporting the acceptance of the normalisation of risk- informed guidelines, which will empower small portfolio dam owners to drive prudent, responsible and defensible management decisions for their revenue-stream constrained dam assets.

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