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16/03/2022

Case study: Creek Damage Repair After Cyclone Debbie

In 2017, Cyclone Debbie raged through Queensland, causing immeasurable damage. In particular, Cyclone Debbie caused immense destruction to the ITV Studios lot, which significantly hindered many of their projects. The team at Total Environmental Concepts were brought in to repair the damage to the surrounding creeks and natural landscape.

RedWhat Happened?

In March of 2017, Tropical Cyclone Debbie landed and swept destruction through Queensland, destroying a significant amount of surrounding landscape and impacting filming schedules. 

There were two creek areas in particular that needed repairing, and due to upcoming projects, the timeline to have this completed was relatively short.

What Was Done?

The repair work was completed in four stages.

The first stage took into consideration work that was done upriver from the already-present bridge. Approximately 2000 tonnes of river rock needed to be removed, and 20 tonnes of imported rock groins needed to be placed. These rock groins were intended to redirect the water. This stage also included the placement of logs in the creek bank, and the removal and construction of a new bridge.

In the second stage, Total Environmental Concepts was tasked with restoring Trails Lake, a concrete creek pool, to its original condition by removing the accumulated bed material. The flooding caused by Cyclone Debbie moved significant quantities of bed material into the pool. Erosion downstream of the pool crest wall also developed since floods from 2013.

The accumulated bed material – silt, gravel and larger cobbles – were removed by a small excavator and by hand as the concrete lining is fragile. A pump located upstream released low-flor water around the works site to below the crest wall.

3000 tonnes of the silt and river rock material that flooded Trails Lake was removed and onsite creek rehabilitation works repaired the damaged area. This proved challenging as the palm trees provided small working space.

In stage three, Total Environmental Concepts was engaged to stop the erosion of the righthand bank downstream of the Trials Lake Crest wall. The team needed to create a constructed cascade to convey water from the Trials Lake to the natural channel downstream and, in doing so, repair the current erosion that undercut the right-hand crest wall of the lake.

The bank revetment was done using graded quarry rock with a geofabric underlay. The bank was shaped as required to position the geofabric. The upper bank batter was immediately revegetated in order to get cover on the erosion-prone surface.

In stage four, the first order stream needed to be positioned into its former channel in order to protect the film set structure and nearby road, and allow for the rehabilitation of a newly formed gully system.

Four main components were proposed:

  • Rock revetment of the right bank at and downstream of the film set
  • The construction of a log training wall to re-establish the right bank commencing at the avulsion breakout point
  • Revegetation of the right bank to secure the creek’s position in the longer term
  • Backfilling of the gully system with bed material (gravel and cobbles) that had accumulated within the nearby Trials Lake on Dungary Creek

The revetment work was constructed by Total Environmental Concepts using graded quarry rock with a geofabric underlay. The rock was carefully placed with existing large boulder worked into the structure.

The creek had broken out of its natural course and severely eroded the outer creek surrounds. The work detail was for the use of rocks to protect the embankment and build a log wall to redirect the creek to erode in natural course.

Total Environmental Concepts’ plan required logs to be recessed into a shallow trench with logs driven into creek beds on both sides and then bolted together under tension, allowing the deflection of water back into the centre of the creek.

The outside of the creek bed was lined with geofabric fill. Material and soil was added to revegetate and reinforces the outside of the bed.

Contact Total Environmental Concept today to discuss how our rebuilding and revegetation services can help you.

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