Cable Bay Road Slip Repairs

In late 2023, Donaldson Civil won the Cable Bay Road Slip Repairs project through a competitive tender.

As the only way in and out of Cable Bay was via this road, closing the road from 9am – 12pm and 1pm – 3pm was deemed the best way to maintain productivity to complete the job before winter, as well as causing as little travel disruption as possible to the community.

The project addressed three underslips caused by the August 2022 flood event, with each site presenting unique challenges.

Site 1 involved constructing a 30m² mass concrete block wall supported by a ground beam with rock-anchored supports. AP65 backfill was placed, and the roadway was rebuilt to restore functionality.

Site 2 required excavating the slip face to create a safe working platform and drill pad. Eight 6m-long 250 SED timber poles were augered and installed with 30m² of timber lagging. Horizontal anchors and whalers were added to reinforce the poles.

Site 3 combined the installation of 13 palisade timber poles to a depth of 5.5m below the road with additional excavation to address challenging ground conditions. An additional 22 timber poles, ranging from 3m to 8m in length, were installed on the face with 63m² of timber lagging. Deadman anchors tied the palisade and face poles together for enhanced stability.

Working on active slip faces across all three sites brought significant safety challenges, mitigated through rigorous planning and execution. Silt fencing was erected downstream of each site, ensuring there were no environmental breaches throughout the project.

With the road closure in place, communication to residents was key. The team sent weekly texts to residents, updating them on the progress of the project, as well as on days when the road was able to be opened during typical closure hours. The successful restoration of the road was celebrated by the Cable Bay community, with over 40 residents attending a thank-you event at the Cable Bay Adventure Park upon project completion.