Houses in Danger from cliff instability / boulder roll
Unstable boulders & undercut cliff above houses
Temporary rock netting encapsulating unstable boulder
Temporary rock netting encapsulating unstable boulder
Project:Rock Cliff Stabilisation, Point Clare NSW
Client:Private Corporate Client
On the Central Coast of NSW a subdivision was carried out in the 1970's near the foot of a steeply sloping hillside, and below a 6½m high sandstone cliff face which had both a large 'undercut' overhang and several large detached boulders perched on the top of the cliff. Later in the 1990's, and because some large boulder falls had occurred in other areas of the Central Coast, the occupiers of the houses in the subdivision below the cliff & boulders raised safety concerns as to the stability of the cliff / boulders with Gosford City Council.
As a result, the firm was engaged to assess the site & public safety risks, and to then provide advice on the necessary remedial actions. This work involved both detailed inspections and geotechnical mapping, design of the stabilisation works and review of the remedial works themselves.
In developing the appropriate design solution, the options considered included boulder removal and rock anchoring, with the encapsulation of some of the boulders by cables and rock netting mesh as a short term 'immediate' option because of the costs associated with the necessary 'permanent' solution.