Category: Infrastructure
Project: CBH Terminal Upgrade
Client: Leighton Contractors, SDR Australia
Location: Albany
Project value: $100 million
Timeframe: July 2004 – Nov 2006
Background
Initially completed in 1956, the CBH terminal’s capacity had grown over the 50 years, to over 420,000 tonnes with grain received by road and rail from producers throughout the region.
Based on these increased volumes, the project sought to add 60,000 tonnes of storage capacity with the installation of ten additional steel storage cells.
In-loading and out-loading facilities also need to be improved to provide a faster and more efficient operation. This comprised of a new underground transfer tunnel and replacement of existing overhead conveyor corridors (two parallel conveyors replaced a single conveyor system). The project also incorporated new boot pits and elevators.
Harley Dykstra was appointed by Leighton Contractors and SDR Australia to undertake survey set out of all structural elements involved in the terminal upgrade.
Challenges
In order to replace the existing conveyor corridors, an accurate survey of the positioning and orientation of the existing attachment points for the corridor superstructure was required.
These points were over 30m above ground level and difficult to access.
However Harley Dykstra achieved results to +/- 3mm through innovative use of LisCAD’s least squares adjustment package.
Reflectorless EDM measurements were combined with traditional prism observations and multiple repetition angle readings from a high accuracy control network.
The drilling of reinforced concrete filled piles for the new cells also took place during winter. As a low lying area, close to the coast, many of the below ground structures and particularly the new rail transfer tunnel and associated boot pit involved working in very wet conditions.
Each of the ten storage cells also had ten individual footings located centrally above their individual piles. Each footing then required ten holding down bolts with a position tolerance of +/-2mm that had to be checked prior to each pour.
Overall this represented a total of 100 bolts per cell that often had to be checked within a very short time frame.
Survey checks were also required for the prefabrication of each cell roof to ensure that the base plates for the overhead conveyor corridors were in the correct position, when the roof was lifted into position. Alignment marks had to be placed on each prefabricated roof and the cell structure, on which it was to be fitted, to ensure that the crane placed the cell roof in the correct orientation before welding commenced.
Upgrade of the rail in-load facility also involved monitoring of the temporary sheet piling. It was critical, for safety reasons, that any movement in this sheet piling was detected and communicated to the project team as a whole.
A new personnel elevator approximately 30 – 40m in height was also installed in an existing building, using block work construction. Harley Dykstra had to monitor construction and provide corrections at regular intervals to ensure that the elevator shaft was vertical and not twisting out of true orientation. This had to be accomplished within very cramped working conditions.
Outcomes
This project relied heavily on accurate data throughout the entire construction process and as a result of Harley Dykstra’s expertise, the project was completed within the design specifications.
During peak times Harley Dykstra was flexible in providing full time survey teams and the consistency with staff ensured the success of the project over the 18 month time frame.
Because of the unique circumstances, with the placement of the new conveyor coridors 30m above ground, Harley Dykstra was required to research and utilise existing software and equipment to its fullest capabilities.
Ultimately the company overcame numerous barriers to achieve its client’s commercial objectives.
