Trenchless assisting Tasmanian natural gas roll-out

Apr 27, 2007

In 2003 the Tasmanian Government announced it would construct a natural gas pipeline network across the state for commercial and residential users, and Trenchless Technology has had a part to play in building this network.

CDP Networks is currently completing construction of Stage 2 of the natural gas reticulation project in Devonport, northern Tasmania, which comprises some 120 km of polyethylene gas reticulation network. The system, when completed for asset owner Powerco Tasmania, will enable supply of natural gas to a potential 7,500 new consumers.
CDP Networks were engaged by Agility (now Alinta) to construct the project on behalf of Powerco. The project required a mixture of plant and construction methods due to the geology of the area. The client was keen to see as much of the project directionally drilled to ensure minimal reinstatement works were necessary, along with lower disruption residents along the route.
Around 75 km of the works were completed using two Case 6030 Drills and an Astec 3238 drill. These were set up as standalone, fully self-sufficient crews, supported with 1.5 tonne mini excavators, sullage trucks and associated plant.
CDP Operations Director Jim Connelly set a series of production targets for each crew, with crew leaders taking responsibility for planning and delivery of those targets. The teams were supported internally by CDP’s own traffic management planning and control crews, operating out of company’s Devonport base.
Flexibility was an important aspect of the works, given the ground conditions in areas of Devonport, and indeed across much of the state, contained rock formations with a compressive strength of 300 MPa.
Consequently, to ensure continued production, it was important for the CDP planners to prepare forward works which would enable a crew to jump across a rock area when encountered, to a new section able to be directional drilled.
The rock areas were then tackled by two special crews operating a 14 tonne Takeuchi and a 12 tonne Komatsu excavator with General Breaker rock hammers to deal with the rock conditions.
Given the relatively new approach of directional drilling for the installation of Tasmanian infrastructure, it was important for CDP to demonstrate from an early stage the reliability of the process, which would avoid third party asset damages. An independent asset locations team operated well ahead of the crews, working from ‘one call’ plans and carrying out all necessary provings to ensure each drill crew had a clear run once on site, and that any route or design changes were dealt with prior to arrival at site.
As a consequence of this focused approach two benefits have been achieved. Firstly, lower cost operations have resulted due to few delays, either by unforeseen damages or downtime awaiting design change approvals. This process also provided Powerco with timely notice for considering amendments, which in turn translated to a solid, professional relationship between the parties.
Secondly, other stakeholders, such as Devonport City Council, were able to gain confidence in what could have been an intrusive project for the community and recognised the HDD process can be productive whilst avoiding disruption through damage to their water and sewer assets.
Importantly, through this project, CDP has been able to successfully achieve a key objective in building a number of local teams, manned by Tasmanians, who through CDP training and experience, have been able to build a successful long-term opportunity in the new Tasmanian gas industry, and in some cases for the first time, are able to work in their home state.
CDP now has an office located in Victoria to expand their infrastructure installation expertise to Southern Australian markets, already completing 110 km of works to date.

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