Scour Remediation Using Composite Systems of Rock Fill & Mattresses
Nearshore pipelines that cross harbours, rivers and estuaries are exposed to a range of hazards including tidal current induced scour, freespans and impact from vessels and anchors. State authorities typically specify a depth of cover of 1,200 mm to top of pipe, which can be costly and problematic to maintain in high current areas.
Subcon recently worked with its client, their design house and their regulator to implement a cost-effective, hybrid solution that provides an equivalent depth of cover to the pipeline.
Firstly, 10 mm rock fill was used to rectify the scoured section of the pipeline in freespan and increase depth of cover to 600mm along the pipeline. Subsequently, 150 mm thick articulated concrete mattresses were used to provide a stabilising layer of armour over the rock to protect the pipeline from the high current and impact from boating traffic.
Recent 100-year floods provided a good test of the system which, with subsequent inspections, showed was intact and promoting sediment deposition along the pipeline.
“I found the depth of knowledge that the team provides and the ability to adapt to changing conditions was impressive. I would use Subcon again as my first preference.”
Boyne Smelters Limited