Posted by: admin November 6, 2015

PROJECT DESCRIPTION:

Scope included slope stabilising with rock anchors and shotcrete. The project required an access road to be built in a precarious location on a mid-level bench above the river and below the lookout to the dam.

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PROJECT DESCRIPTION:

Investigation works were carried out at three points in the dam’s 200mm thick concrete spillway. The works involved cutting a 700mm x 700mm square out of the face of the dam, excavating down to expose and inspect the anchor bars below. Each investigation point had to be opened and reinstated in one shift. The client was able to then gather important data required for future maintenance of dam which is the main water supply for Noosa Shire Council.

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PROJECT DESCRIPTION:

Winner – Category 2, NSW CCF Earth Awards 2013

The Burrinjuck Dam Access Upgrade project had its fair share of complex challenges.

Burrinjuck Dam is a historic State Water asset. Construction of the dam started in 1909 and took over twenty years to complete. It is located 34 km south west of Yass, NSW over the Murrumbidgee River. During its construction a cableway was erected across the spillway face to ferry personnel and materials across the gorge. For many years the cableway, fitted with a lifting hook and man box was the sole method of haulage for materials and personnel.

The hook and man box run along two axis – north/south and east /west. The north/south axis runs on cables from a head tower above the northern spillway, to a tail tower above the southern spillway. To position the hook and man box along the east/west axis, the two towers move along rail tracks on benches cut into the steep rock faces of the gorge above two spillways.

The purpose of the upgrade was to address OHS risks associated with transporting personnel in the cableway man box (the only means of accessing the southern cable tower), and to provide reliable logistic arrangements for handling materials.

The works involved design, fabrication, installation, construction, testing and commissioning of a new steel trussed bridge for alternative access across the southern spillway from the dam parapet to the cableway’s tail tower and new steel trussed tower stairs and access platforms to improve access from the parapet wall down to the north and south spillway trainer walls.

The isolated location of the construction site required special consideration to emergency response and evacuation procedures, which were incorporated in the site induction and safety training. Additional working at heights safety and emergency evacuation training was essential. Much of the work was carried out using abseiling harnesses on steep rock faces above the dam wall and water storage, and to and from a man-box suspended from the cableway up to 140m above the river bed.

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PROJECT DESCRIPTION:

Spillway and Embankment

Grahamstown Dam is the major water storage reservoir of the Hunter Water Corporation, supplying the Newcastle and Lake Macquarie regions. To increase storage, improve water level control systems and boost flood discharge capacity, Abergeldie were contracted to construct a new control structure, a zig zag concrete spillway and major new earth embankment.

Complex Challenges:

An adjustable steel formwork system was developed for the construction of the labyrinth spillway to achieve a tolerance on the weir crest of -0+2mm.

An original requirement for the staging of works was the completion of the control structure and a portion of the spillway wall to enable control of the water level in the lake. Abergeldie proposed and implemented an adjustment to the order of works by constructing diversion works prior to completion of the control structure. This allowed works to the main embankment to commence earlier and accelerated the construction process.

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PROJECT DESCRIPTION:

Abergeldie completed works immediately below the spillways of Queensland’s Wivenhoe, Somerset and Borumba Dams to repair damage caused by overtopping and emergency releases during the 2011 and 2013 floods.

At Wivenhoe dam, most of the repair works were to the recreational area on the southern embankment of the river below the dam wall. Roads were rebuilt, pavements stabilised, new canoe access tracks created and extensive earthworks carried out to stabilise and re-profile the river embankments.

At Somerset Dam, extensive remediation works were carried out to the severely eroded right bank of the Stanley River. Abergeldie installed a new reinforced concrete spillway training wall, carried out repairs to scours, installed a new access road, replaced guardrails and handrails and installed rock protection and rip rap to stabilise embankments.

Works at Borumba dam included remediation of the dam’s concrete embankment toe, valve house, spillway and plunge pool areas, and reinstatement of handrails and access pathways. To stabilise the river banks and bed, rock rip rap was placed downstream of the spillway and steel reinforced rock protection was installed adjacent to the spillway itself.

At all three sites, care was taken to protect the riparian habitat. At both Wivenhoe and Somerset dams there are important populations of Australian Lung Fish, both within the dam reservoirs and in the rivers downstream. The waters above and below the Borumba dam are home not only to Australian Lung Fish but also to the endangered Mary River Turtle, which is found only in this one location.

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PROJECT DESCRIPTION:

Abergeldie were engaged to construct a weir and associated works in the Logan River, to replace the existing weir that had been damaged by floods. The works included a temporary water flow diversion, retaining walls, structural concrete, steelwork and pipe work, erosion protection and installation of rock anchors.

Complex Challenges:

Access to the site was available from only one side of the river, requiring a temporary access road to be built across the water course to facilitate works from both sides. Temporary weir and earthworks were built to divert the water flow away from the works site. Safety and environmental management were primary issues in planning the project.

Contingency plans were prepared to address the possibility of flooding during any significant rain event, with a view to minimising the risk to personnel and possible damage and delay to the works. As the weir is an integral element of the local fresh water supply, a “no compromise” approach was taken to environmental controls to prevent contamination.

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PROJECT DESCRIPTION:

Abergeldie were engaged to carry out remedial work to increase the structural safety of the more than 80 year old Chichester Dam, while maintaining its storage and operational capacity.

Works included:

  • Raising the height of the left parapet wall
  • Drilling a network of pressure relieving drainage holes
  • Reconfiguring the right parapet to divert water flows
  • Associated minor works

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PROJECT DESCRIPTION:

Thrust Block Remediation

Partial demolition and re-instatement of three large concrete thrust blocks, including removal and re-installation of services. The thrust blocks form part of the hydro power station, located in the base of the Googong Dam wall.

Complex Challenges:

The project involved removing a large amount of defective concrete from the top and sides of the main outlet thrust blocks from the dam. The proximity of live water mains demanded that the demolition work be carried out with care and delicacy, with continuous vibration monitoring to ensure that no damage was caused to the cement lining of the existing pipework. Initially, all concrete demolition was carried out by hand due to limited space and restricted access into the chamber. This restriction was overcome by lifting a small excavator and hammer into the chamber to accelerate the process.

Posted by: admin November 20, 2015

Project Description:

Construction and commissioning of a 3 Megalitre reservoir pump station and 400m long rising main, including conduit runs, electrical installation and hypochlorite dosing facility. Associated civil works included construction of an access road and various concrete works including a valve pit and retaining walls. Then commission and cut into existing mains.

Complex Challenges:

The construction site was extremely steep, with restricted access for construction equipment and very limited space for fabrication, assembly or storage of construction components. The reservoir was constructed using steel plates, fabricated in an off-site workshop to the correct size and shape. The plates were transported to the site to be erected and welded piece by piece, followed by a multi-step painting process under stringent quality control conditions. The result was a solid, durable, hydrostatic steel reservoir for potable water storage.

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Project Description:

Auxiliary Spillway

Excavation of rock for the contouring of the spillway inlet chute.