Cliff face to be stabilised

Gosford Council has resolved to stabilise the cliff face near the Pearl Beach Rock Pool at a cost of $140,000.

According to a council report, the stabilisation works will consist of a combination of wire mesh, rock bolts, shotcrete and other works including measures to prevent future erosion to the rock surface.

The report also stated that this option was the preferred stabilisation method for the Pearl Beach Progress Association and The National Trust of Australia.

Another method was adopted by council at a meeting on May 6, at a cost of $180,000 but was later rejected by the local progress association and the National Trust.

It would have seen a shotcrete membrane applied over the entire rock slope and was rejected as "unsightly".

The cliff face, along with the rock pool, are both classified by the National Trust of Australia.

In a letter to Gosford Council, conservation director for the National Trust of Australia Mr Graham Quint wrote: "Given the need to reduce public risk and in light of the proposed use of shotcrete, the Trust would suggest that limited excavation and reshaping of the cliff may be a preferable approach".

"An excavated cliff face would still provide a more aesthetically acceptable backdrop to the pool than shotcrete," Mr Quint wrote.

"Given the highly uneven surface of the cliff, it is hard to accept that the shotcrete will be so well laid that it will not need some maintenance itself in time, particularly as it will be subject to wave and salt action on one side and stormwater/groundwater action on the other.

"The use of stainless steel mesh securely bolted into the rockface appears to be perfectly adequate for the purpose and, as the mesh will be made of stainless steel, maintenance should not be onerous.

"Whilst the mesh will have an impact upon the look of the cliff, it will be greatly less than that of the shotcrete and is much more easily maintained and/or replaced in future.

"A stepped final profile, perhaps in combination with stainless steel mesh, would address many of the safety concerns, whilst preserving a natural stone cliff face, albeit, one that will have been worked by the hand of men rather than nature."

As a result of communication between council and the trust, the design was revised and reviewed by council officers and supported by the national trust and local progress association group.

The revised design will include preparing the face of the cliff for stabilisation by removing loose blocks, soil, trees and vegetation.

The new design also includes draping and pinning double dip galvanised four millimetre mesh loosely to the rock face, installing rock bolts to the rock face and shotcrete sprayed where appropriate to prevent further erosion or the detachment of blocks.

"The estimated cost of the design option three is $140,000 which is a reduction of $40,000 from the previous design and will be funded through the Budget Review Process as per previous Council Resolution," the council report stated.

"The necessity for ongoing maintenance will be funded through the recurrent budget of Open Space and Leisure Services as required."

Council agenda CIT.27, 2 Jun 2009