The dam, constructed in 1971 with a catchment area of 750km2, is a 27m high, 7.5km long earth rock embankment. The reservoir impounded by the dam is a major source of water supply for the cities of Townsville and Thuringowa.
NQ Water, owner and operator of the dam, is undertaking the upgrade based on the recommendations of a panel of dam safety experts. The work involves lowering the spillway, installing new spillway gates, constructing sand filters and supporting earthfill, augmenting rock riprap, and associated works.
The upgrade, to be completed by 2008, will ensure the dam is capable of withstanding a rainfall event that, on average, is estimated to occur only once in 400,000 years. The first stage of the work which included lowering the spillway was completed in 2003. A new spillway gate design has been prepared, with three gates to span the 40m wide spillway.
The gates have been designed by GHD-MWH, who are also responsible for the detailed design and project management of the upgrade work.
The gates are expected to be in place by the end of 2006.