Project Description

The new bridge spanning Kilcoy Creek at Wunulla Lane was part of the 2013 NDRRA flood restoration program to replace the old timber bridge washed away during the 2013 floods. Although only a single span bridge in a rural setting, the new bridge was required to withstand flood velocities of up to 4m/s and a two tonne log impact up to 2m from the flood surface. Scour was also of concern for up to a 1 in 100 flood event along with the added pressure of a debris mat during flood events up to 3m depth acting on the bridge superstructure or the piers.The geotechnical profile indicated the presence of fresh crystalline Granodiorite rock beneath layers of loose saturated sands which were up to 8m below ground level. The high water table in conjunction with the layers of loose sand excluded the use of open hole bored piles and the underlying fresh rock was identified in the geotechnical report as potentially making the
installation of steel liners and rock sockets for traditional bored piles “difficult” and “slow”.

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