• Construction of a cofferdam at the downstream end of the tunnel to facilitate dewatering;
• Internal remediation works, including the replacement of existing bolts, spot bolting as required with dental concrete at isolated locations, and the application of fibre reinforced shotcrete extending from the roof to the base of the tunnel walls;
• Establishment of equipment laydowns; and
• Upgrades to existing access roads for construction and maintenance vehicles.

The Balickera Tunnel is a known roosting site for several threatened microbat species and the construction work was deemed to have a biodiversity impact on these colonies due to the temporary exclusion from the tunnel. The remediation works were carried out in accordance with a species impact management plan. Further, major flooding due to recurrent wet weather also presented significant challenges to the construction team with constant monitoring of water ingress compared to achievable dewatering rates needed to ensure safety during construction.

The project team, in close collaboration with the Geotechnical Engineer and Hunter Water, developed a new methodology to install rock bolts within the tunnel. This doubled the productivity of rock bolt installation, achieving 4m/12-hour shift, saving significant costs for the client.

The completed rehabilitation of the Balickera Tunnel, now ensures ongoing reliable transfer of water from the Williams River to Grahamstown Dam (via Balickera Pump Station) which holds over 65% of the total water storage for the Lower Hunter Region.