FLAGSTAFF ROAD LANDSLIP
In 2011 a section of Flagstaff Road within Isla Gorge National Park had been repaired using a gabion basket wall. In 2014 the gabion basket failed and the road required repair work and an alternate solution to provide safe access along Flagstaff Road.
CMC was engaged to cut the road further into the hill and move it approximately 15 metres laterally to within a major escarpment which provides a foundation on existing material. This solution deviated the existing roadway through a 200 metre section onto new pavement, before aligning it back with the existing roadway.
Works included construction of new concrete lined drains and channels, upgrading of existing road furniture, unbound and bound pavements and bituminous spray sealing. Additional variation works involved utilising spoil from the excavation within a gully on Flagstaff Road. This raised the existing gravel roadway by approximately four metres within a neighbouring section of Flagstaff Road, and reduced carting of spoil off site.
HIGHLIGHTS & OUTCOMES
Completed two weeks ahead of schedule.
Worked collaboratively with the client and Queensland Parks and Wildlife Services to identify acceptable native species for revegetation.
CMC created a more natural drainage structure by changing the original scope from shotcrete lined catch drains over the top of the escarpment, to rock lined channels, chutes and berms which flowed into existing structures.
Committed to working safely, CMC identified that the rock stratum within the excavation was highly variable in nature and therefore blasting may have created an unnecessary risk. It was discussed at length, and agreed with the client, that blasting was not a safe option as the activity could not be adequately constrained, and in fact may not have worked due to the type of strata.