pumping & pipelines
~ refereed paper
diameter, a pipe with 'memory' has significant stored energy with high impact potential if not managed with caution , (likened to a large, stretched elastic band). The risk of pipe 'memory' was significantly red uced on warm/ hot days when the pipe heated up and 'relaxed' during the unravelling phase. Another manual labouring role in the plough installation process was pipe joining. During ini tial trials, two types of joint were trialled for HOPE pipe, butt welded and electro fusion. Both method s provided a weld join with butt welding providing a pipe face to face weld whilst an EF weld provided a coupling that fused to the outside of the pipe. Due to the simplicity and ease of use the EF weld was the method used on mainline activities. EF welding provided a safe, quality join through the employment of a computer driven weld unit connected to a power source and then hooked to the EF coupler. The computer would gauge the parameters of the coupl ing and feed power into the unit accordingly thus creating a sound weld . Not one weld failed over the course of 519kms of HOPE pipe installed and tested. Whilst there were some minor strain injuries associated with this emerging technology, the safety performance of this installation method was excellent with no LTis throughout the entire plough operation. In times of high liability and the need to conti nually strive for improvements in safety, the vibratory plough has not only provided a major leap in the technology of water pipeline laying but an equally large leap in construction safety. There is of course a risk of becoming complacent with safety when the perception is that there are no risks. It is still essential to continually reinforce the safety issues wit h the comprehensive approach of team briefings and too l box meetings as practiced by Nacap Australia.
Landowner impacts Landowners affected by this project were over 600 with zero landowner complaints for this project. This is a t estament t o the success of the plough, commitment to sound construction and design management and strong environmental practise.
Quicker construction Vibrat ory ploughing is a far less involved process than that for open cut pipe laying. Ploughing involved stripping of vegetation and topsoi l for vi bratory plough works only in areas where the RoW had localised elevation changes that required removal for pipeline performance reasons or where the vertical profile was unsuited for ploughing such as at washouts, channels (dry), water courses {dry) and the like.
Pipe stringing and ploughing Pipes were delivered in coils to the ROW and laid out in preparation for ploughing.
Jointing and fittings Jointing of pipe was undertaken at jointing pits, excavated prior t o ploughing. These pits had sufficient length t o provide for overlapped pipe ends t o be cut and stress free connection of the pipe. Jointing methods were by either electro-fusion or butt weld.
Reinstatement Immediately followi ng the compaction of the rip line and installation of appurtenances, the reinstatement of the ROW was conducted. The number of mechanical items requi red on site was markedly reduced as was the manual handling of materials and equipment and the exposure to working near trenches. The rate of laying was also substantially quicker than traditional methods with four kilometres of pipeline laid per day per machine possible (in favourable ground conditions we achieved an installation rate of over ?km/day). Landholder impact was substantially reduced with the pipeline const ructed and land reinstated t o pre-construction condition within 1 to 2 days.
Major Lessons Learnt There were several lessons learnt on this project, particularly: • Adopting a close worki ng relationship within the t eam broke down traditional approaches to the design process. This was critical and was achieved by co-locati ng client, construct or and design personnel. • Pipe supply was critical so a business partnership with a pipe
supplier was established to ensure pipe supply had surety of delivery to suite the project requirements. • Wh ile this was a lump sum contact Nacap, WorleyParsons and GWMWater cooperated in an 'alliance' style relationship which enabled this innovation to be achieved and deliver efficiencies on th is complex project.
Conclusion With the technology in very early stages it is clear, based on the multifronted success of this project, that there is a place for this technology within the Austral ian pipeline industry. A brief review of current projects in Australia point to the possible application of this installation method in the field of Coal Seam methane extraction (which is currently being demonstrated by Nacap on HOPE pipelines up to DN315 in Chinchilla, Queensland). The use of vibratory plough technique significantly red uced the impact on vegetation and farm ing land and reduced safety hazards that are normally associated with pipeline construction. The vibratory plough technique for laying small bore PE pipe is seen as an innovation that will have significant benefit for the wider Australian water industry.
Acknowledgment We acknowledge the support of GWMWater in this process.
The Authors
Malcolm Potts is the Engineering Manager for the Victorian wat er business of Worley Parsons Services Pty Ltd, malcolm.potts@worleyparsons.com
James Povey is a Project Manager for Nacap Australia Pty Ltd, j.povey@nacap.com.au
water JUNE 2009 57