Slope Instability Affecting Water Main

Castle Hill

In 2012, a significant localised landslide occurred in the Castle Hill area which had the potential to cause damage to a large [j450 mm] Sydney Water water main.  Subsequently, Sydney Water sought advice from a large multidiscipline engineering firm as to the remedial works necessary to remediate the landslide.

Later, and because of the relatively large cost of the remedial works proposed by the multidiscipline engineering firm, Sydney Water requested SCE to inspect the landslide and advise as to:

  • the efficacy of the remedial works proposed;
  • the probable cause(s) of the landslide;
  • whether there were alternate, more economic remedial works.

Subsequently, and after its investigations, SCE advised Sydney Water that:

  1. As the landslide had been primarily caused by the concentrated discharge of stormwater drainage by the Local Council, the concentrated discharge should be rectified before any remedial works were undertaken.
  2. If the concentrated discharge was appropriately remediated, then the landslide repair works would be relatively simple and only embrace minor earthworks.

Sydney Water then chose to implement the SCE recommendations.