Stabilising works to cost $2.5M

Stabilising work on Pearl Beach Dr may cost up to $2.5 million dollars, according to two options presented to Gosford Council by Shirley Consultancy Engineers.

Council had asked that a concept design of the necessary risk reduction and remedial works be prepared, and the cost of the works be determined.

Council officers have reported that two alternative concept designs had been prepared which included the realignment of much of the road to provide a rockfall drop zone, upgrade of road stormwater drainage, stabilisation of fill material below the pavement, retaining wall and batter construction, excavation to improve sight distance, pavement widening, loose rock scaling, rock bolting, shotcreting and other associated works.

The report stated that "either concept has been estimated by the consultant to cost in the order of $2.5 million."

A third, more detailed concept option was also currently being prepared.

The report stated: "This is an amalgamation and refinement of Options A and B where features of both are being applied at various locations along Pearl Beach Dr.

"The preferred option is to be verified by an experienced geotechnical engineer."

It stated that there was currently a grant offer of up to $150,000 from the Natural Disaster Mitigation Program (NPMP) to carry out initial slope stability risk reduction treatments at Pearl Beach Dr, which was equally funded by Federal and State government and was conditional on council providing a further contribution up to $75,000.

Officers stated that the preferred concept design would need to be completed and adopted prior to development of specifications for the NPMP treatment works.

"This will avoid a scenario where parts of the slope are stabilised, only to be removed where a different treatment is developed in the final design."

Works anticipated to be carried out using the initial $225,000 available through the NDMP would include scaling and removal of loose and potentially unstable rock and soil material on the slope above the roadway, installation of rock-bolts and rock dowels into suitable rockfall hazards, installation of rockfall mesh where required, application of sprayed concrete to suitable hazards, and if ponding of stormwater and seepage remains, carry out the highest priority drainage improvement works and/or repairs.

Council stated that it was also proposed to fund the design plans for the stabilisation work through the NDMP, including the associated geotechnical evaluation and assessment of priority, during the first half of this year.

"Assuming tenders are called immediately thereafter it is anticipated that the works can be completed by late 2008," officers stated.

"The above activity is intended to be the first of a number of stages to reduce risk to an acceptable level.

"Future stages would be prioritised as funding is made available to progressively address the greatest inherent risks.

"The ultimate result would be a completely reconstructed, road free on intolerable slope stability risk."

Council has resolved to source its $75,000 share of funding for the Natural Disasters Mitigation Program from a future capital works Program Budget Review.

Council agenda SF.11, 4 Mar 2008