When the contractor chooses a Vermeer® T955 (298 kW, 43.4 tonnes) track trencher for the project, it reflects well on Vermeer and its dealer, Vermeer Sales & Service Queensland Pty Ltd.
The project is the 27 km Gove G3 Borefields Pipeline being built for Alcan in the Northern Territory as part of its $2 billion alumina refinery expansion project. Brisbane-based Greene and Associates Pty Ltd (GA) was chosen as the project contractor, while its pipeline construction subsidiary (Greene Pipeline Services) partnered with welding specialist Greendesert Pipelines (GP) to construct the potable water pipeline. The partners purchased the Vermeer T955 to complement their existing equipment fleet.
GA founder and managing director Mark Greene has more than 30 years of experience in the mining and resources industries, covering construction, manufacturing, and maintenance activities.
Critical timeline
Because water is required for the start-up of the expanded refinery, the timetable to complete the pipeline is critical. GA first visited the site in August 2005, and mobilised on site in October, with the full workforce in place by mid-November. The timing of the project meant that some construction coincided with wet season.
To stay on schedule, GA built an all-weather road along the route of the pipeline. While parts of this path run parallel to an existing conveyor, other parts run through virgin bush. A combination of spotters on the ground, Global Positioning System (GPS), and dozers were used to push a track through, which widened to the full 20 metre easement using the dozer. Battered drains were installed to control runoff as part of the environmental management plan.
This allowed GA to truck the predominantly 500 mm diameter high-density polyethylene (HDPE) pipes from the holding area to the pipe route for stringing, regardless of weather (250 mm diameter pipe was used between the bores and the aerator).
Safety controls
As part of its safety controls, GA installed and backfilled the pipe each night, so that no trench was left open overnight. The Vermeer T955 trencher made the backfilling task easier by leaving the finer spoil closer to the trench. GA chose the Vermeer T955 after determining the size of machine required, and comparing the alternatives available on the Australian market.
Greene outlined the reasons for the final choice saying, “At the end of the day, the prices were similar, but we were swayed by the number of Vermeer trenchers working in the field with credible work histories, and by the resources that the dealer had available to support Vermeer equipment in the field. This is very important when key equipment is working in remote locations on time-critical projects.
“The dealer informed us that although the T955 was slightly lighter than another machine we were looking at, the design of the Vermeer machine meant that it was capable of outperforming the heavier machine. The T955 has more than met our performance expectations in the time that it has been working at Gove.”
On-Site Training
An additional factor in the T955 purchase decision was the machine’s operator friendliness, with its ability to sense changes in trenching conditions and vary trenching speed automatically, using the TEC 2000.2® electronic control system.
GP founder and general manager Kerry Harvey has operated bucket wheel trenchers for 12 years, but found that the Vermeer T955 was in a different league compared to other trenchers in terms of performance, operator comfort and ease of operation. “We put the machine straight into rock on the first day, and its performance far exceeded my expectations. After a few of hours of training, I found it easy to operate, and the climate-controlled cab and raised operator position were a big improvement (over past machines). I was also surprised by how well the trencher handled the wet conditions at Gove.”
The trencher is working in cemented ironstone laterite with a strength of 15- 25 MPa, and medium abrasiveness. Depending on conditions, between 200 and 700 metres of trench are completed in a day, with the trencher working a 12-hour shift on weekdays and eight-hour shifts on Saturdays and Sundays. The standard Vermeer tool pattern is being used, and this has proved satisfactory in terms of production and wear. An 850 mm chain width is used for the 500 mm pipe, with a 650 mm chain used for the smaller-diameter pipe. The specification calls for an 1.5 metre (5 foot) trenching depth.
GA is tendering a 71 km Sunwater pipeline project in the Bowen Basin (Central Queensland), which suits the Gove project completion in terms of timing, as it would allow GA to keep most of its crew together. Continuity is important to fully utilise the Vermeer T955 and the experienced pipeline crew. With this combination Greene and Harvey see that their pipeline company can compete for work around Australia and offshore. With the volume of work planned in Australia over the next few years, they are sure that “the T955 won’t be the last Vermeer trencher that we buy.”