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Permanent multi-strand ground anchors and spillway strengthening

Project Overview


Owned and operated by State Water Corp, Blowering Dam is the sixth largest embankment dam and ninth highest in Australia.


The main construction works completed by MacMahon's consisted of a parapet wall on top of the dam wall crest and raising the spillway training walls.

The work on the crest wall and spillway was proven to be successful immediately after the completion of the works to raise the crest as the region experienced severe rainfall in December 2010 resulting in the dam exceeding its capacity.


Geovert Solution


Geovert completed several packages of work during the safety
upgrade firstly installing rock bolts for the spillway strengthening and
widening and secondly post tensioned high tensile bar anchors through the crest and multistrand anchors through the new wing walls. Works on the 45° slopes and spillway required roped access and winches to complete the drilling safely in freezing temperatures during the winter to over 45° heat in the summer months.


The permanent post tensioned anchors were installed through the crest towards the end of the project to depths of 30m and consisted of 19No. 15.2mm strands. Precision drilling was required along with
meter by meter video surveillance of the drilled holes prior to the pregrouting process. Anchors were tested and locked off with re-stressable heads to allow for continued monitoring of their
performance on State Water’s asset.


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