Bundaberg Burnett River Channel Maintenance Dredging
Scope of Works
Severe flooding impacted the Burnett River. As a result, the navigational channel required dredging to restore the depth of the river’s navigational channels adjacent to Kirby’s Wall. A total of 65,700 cubic metres of sand and gravel was removed from the channels and placed behind Kirby’s Wall.
TMR nominated two specific dredge areas:
- Dredge Area A, adjacent and upstream of Kirby’s Wall, required 36,000m3 of material to be removed, and
- Dredge Area B, downstream of Kirby’s Wall with almost 30,000m3.
Dredging to a maximum depth of 2.3m below LAT was required in both channel areas.
The dredged material was required to be placed behind Kirby’s Wall to fill in the area between the river bank and the rock wall. The spreader barge spread the material evenly to a height below +0.3 LAT.
- Dredge & Booster – The 450mm cutter suction dredge the Nu Endeavour was used for this project. In addition, a booster pump and pontoon were connected directly to the rear of the dredge to extend its pumping capability to reach the required distances to the disposal area (up to 1,700m).
- Spreader Barge – We undertook the replenishment works behind Kirby’s Wall with a spreader barge with a three-wire anchoring system. The three-wire system allowed the spreader barge to winch across the fill area while discharged material. In addition, to ensure anchor lines didn’t come into contact with the top of the wall and cause damage, floating pontoons were employed adjacent to Kirby’s Wall.
- Support Vessels – Other supports vessels included: a Workboat, the MV Tramp; Fuel Barge; Anchor Barge and several smaller tender vessels.
Dredging commenced at the upstream end of the channel and progressed downstream. The team added the additional pipeline for works in Dredge Area B.
Neumann Dredging completed the project on a 24 hour, seven days per week basis.
- Use of spreader barge to place the dredged material behind Kirby’s Wall
- Use of a barred Bucketwheel to exclude oversize material from the pumping system
- Spreading the dredged material evenly and with tolerances with the spreader barge behind Kirby’s Wall
- Post-flood debris and obstructions in the dredge area
- Dredging unpredictable material – coarse sand, gravel, cobbles and boulders.
- Wear and tear on machinery and equipment.
- Strict dredging and fill tolerances.
- Interfacing dredging works with shipping, and other marine vessels traversed the work areas.
- We had to maintaine access to the busy boat ramp adjacent to Kirby’s wall.