Decked Rockfill Dams In Tasmania

The construction of dams for the seasonal storage of water began with the arrival of European settlers in Tasmania during the early part of the 19th century. A variety of small water storages with dams <15m high were constructed to meet the needs of local communities. The construction of ‘large dams’ began in Tasmania with the Lower Reservoir during the 1850s. It was Hobart’s first seasonal water storage.

During the second half of the 19th century three water supply dams were completed to serve Hobart and Glenorchy. These dams, Lower Reservoir, Upper Reservoir, and Tolosa Reservoir, had a combined storage volume of 945,000m3 (ANCOLD, 1990). With developments in mining, agriculture and industry the need for reliable supplies of water increased notably. The result was a near exponential growth in the construction of large dams (as defined by ANCOLD) for water storage during the 20th century.

The majority of these dams were rockfill (36) and earthfill (34) embankments. Other types included concrete gravity (7), concrete buttress (2) and concrete arch (5). There are 21 decked rockfill dams, i.e., ~25% of all large dams. Most of these are concrete faced rockfill dams (CFRDs), two are bituminous concrete faced rockfill dams (BFRDs). The first CFRD was constructed in 1907-8; the last was completed in 1993. This paper covers the development and performance of decked rockfill dams in Tasmania.