Benambra Mine Remediation

The Benambra mine was an underground mine which operated for just four years in the 1990s before being abandoned.The Victorian Government then contracted Abigroup to remediate the dam and encapsulate it. Abigroup subcontracted Birdon for aspects of this work.

This included:

  • Levelling the stored tailings within in the dam to ensure minimum coverage of 2 metres of water over the contaminated material
  • Distribution and spreading of limestone sand over the submerged contaminated material
  • Laying a jute mesh over the entire dame bed to encapsulate the material.
Port Phillip Bay

Birdon has been Parks Victoria’s Dredging Contractor for more than 15 years to date.

The work involves maintenance dredging at various sites around Port Phillip Bay and Westernport VIC.

Birdon’s responsibilities included:

  • Supply and establishment of all required equipment to each site
  • Dredging of individual sites for navigation using cutter suction dredge with discharge to nearby beaches for sand re-nourishment
  • Maintenance of all equipment used.

The longstanding relationship with this client can be attributed to Birdon’s commitment to continual improvement. Birdon’s ongoing evaluation of the dredging program and development and implementation of new procedures has resulted in improved dredging efficiency. It has also delivered a cost saving to Parks Victoria by reducing its supervision and contract administration requirements.

Murray Mouth Dredging

Birdon was awarded a three-year contract by South Australia Water Corporation for the dredging of the Murray mouth entrance and adjacent channels which was extended by another three years.The project involved two cutter suction dredges plus a booster pump operating on a 24 hour a day, seven days a week basis.

The Murray Mouth, near Goolwa in South Australia, is a dynamic system influenced by the flow of River Murray water through the barrages and tidal movement from the Southern Ocean.

Periods of low flow, such as the Millennium Drought in 2002, have led to the mouth threatening to close. The mouth was dredged for eight years from 2002 to 2010, during the Millennium Drought, to keep it open.

Birdon began work in 2007 and continued until2010. Birdon was then awarded a further three-year contract which was suspended in 2011 when flood waters negated the need for continual dredging.

The contract was a turn key solution involving provision of all plant, equipment labour and services including construction of pipeline, operation of cutter suction dredge, booster, workboats plant machinery and associated equipment and vessels.

Loy Yang

Birdon was contracted to dredge 1.4 million cubic metres of consolidated ash from two primary settling ponds at Loy Yang power station. The material was pumped 1km to a newly constructed void for dewatering ad long term storage.

AGL Pty Ltd operates Victoria’s largest coal mine and power station –Loy Yang –which supplies one-third of the state’s electricity.

During the production process on site, fly ash and bottom ash build up in the main settlement ponds. This requires regular removal and transfer to a storage area.

The work was undertaken using a 10-inch cutter suction dredge with the material pumped via a temporary pipeline to the elevated storage void.

All work was undertaken while the power plant and settling ponds remained in operation. This required careful planning to achieve settling requirements while still leaving enough water for dredging operations.

Birdon worked closely with AGL to amend the working area and adjust the scope of work which allowed the ponds to remain operational throughout the project.

Lakes Entrance Dredging

Lakes Entrance is home to the largest commercial fishing fleet in Victoria and increasingly is used by local and visiting recreational vessels. Regular dredging at the entrance to the Gippsland Lakes has occurred for more than 120 years and has been essential for maintaining access between the Gippsland Lakes and Bass Strait since the permanent entrance was constructed in 1889.

GippslandPorts awarded Birdon the contract for the hire and operation of a cutter suction dredge for 18 months while they sourced their own dredge.

Birdon undertook the following scope of work:

  • Supply, establishment and operation of cutter suction dredge discharging to fixed slurry pumping station at Lakes Entrance
  • Dredging of boat harbour with discharge to beach for re-nourishment at Port Welshpool
  • Maintenance of dredge and pipeline
  • Development of preferred dredging practices

Birdon subsequently won the tender to build and supply a purpose-built cutter suction dredge for Gippsland Ports.

Great Lakes Dredging

Birdon delivered maintenance dredging of Lower Myall River entrance to aid navigation and replenish beach sand in eroded areas within Port Stephens. This project involved dredging about 110,000m3 of sand from the eastern channel of the Lower Myall River, near Jimmys Beach, and relocating it to the badly eroded Winda Woppa sand spit.

Work was undertaken in three phases:

  • Excavation phase
    Sand was excavated from the area of the channel above mean water level using a 30-tonne excavator and loaded into articulated dump trucks. This was then transported and placed to form a perimeter bund for the sand stockpile.
  • Dredge Phase
    Birdon used a 10” cutter suction dredge for removal of the remaining material from the river channel. This material was then pumped up to 2km viaa temporary pipeline to be stockpiled or for beach renourishment.
  • Deposition
    Birdon placed the dredged sand along a 600m section of Jimmy’s Beach to provide protection from erosion and restore the beach.The remaining material was deposited in a nearby stockpile for future beach renourishment.
Garden Island Dredging

Birdon was responsible for maintenance dredging activities at Fleet Base East and Garden Island Naval Base wharves to maintain operational and functional capabilities for the Department of Defence.

Garden Island Naval Base is located within Sydney Harbour, about two kilometres east of the Sydney CBD.The work involved the mechanical excavation, dewatering, treatment and disposal of approximately 10,000m3 of contaminated material to an onshore registered waste facility. Due to the limited available land area at Garden Island, the contaminated sediments were solidified by addition of polymer in the on-water hoppers and loaded directly onto trucks for transport to landfill.

Another 10,000m3 of clean material was also excavated and disposed of using bottom dump barges to an offshore spoil site.

The work included site establishment, the supply of all materials, plant, equipment and labour required for the completion of the dredging and disposal activities as well as completion of all survey activities associated with the works, including calibration, pre-dredging survey and post-dredging surveys.

Broadwater Channels Dredging

This project consisted of maintenance dredging of navigation channels in the Broadwater on Queensland’s Gold Coast. The scope includes removal of 110,000m3 of sand from the north and south channels as well as South Wave Break Island channel.

Birdon used a cutter suction dredge to remove sand from the North Channel and pump it, via a temporary pipeline across the southern tip of South Stradbroke Island, for discharge into the ocean-side tidal zone.

The sand from the South Channel and South Wave Break Island Channel was pumped to the stockpile on the spit for storage and future beach renourishment. Birdon delivered the project without disrupting existing waterway users.

Newport Waters

Birdon undertook maintenance dredging works within the Newport Canals for Moreton Bay Regional Council.The work included the removal of sediment within the canal system using a long reach excavator mounted on a hopper barge.

Sediment was excavated from the seabed and loaded directly into the hopperbarge before being transferred to a larger barge about 1km offshore. Once the larger barge reached capacity (500 cubic metres) it was then towed to Mud Island for disposal.

South Australian Common User Facility

This project included maintenance and capital dredging around the common user facility (CUF) and ASC ship building facility within South Australia’s maritime precinct, Techport Australia.

The CUF is a State-owned facility and consists of a ship-lift, wharf, ship transfer system and dry berth for shipbuilding and ship maintenance activities. Its primary purpose is to support the construction of the Air Warfare Destroyers for the Royal Australian Navy.

The scope of work included:

  • Capital dredging of 54,000m3 of predominantly hard material to allow for the extension of the CUF wharf
  • Maintenance dredging to remove infill sediment from both the CUF and ASC ship lifts
  • Maintenance dredging of infill sediment from under the ASC wharf area.

Birdon pumped the removed sediment, via a temporary pipeline, more than 2.5 km to designated settling ponds. Due to the distance, Birdon deployed booster pumps to ensure efficiency. The water was allowed to settle and monitored for quality before being returned to the river. Key to securing this bid was Birdon’s innovative solution which involved using a low pontoon to manoeuvre the pump under the ship lift. This allowed for dredging under the ship lifts without the need to remove the deck timbers of the structures. This resulted in minimal docking restrictions during the work.