When a B-Double fuel tanker ran into an embankment it rolled and emptied its load of fuel into the storm water drains running along the Federal Highway. The fuel ignited causing serious damage to the asbestos pipes and in doing so potentially created a huge environmental issue. Whilst the majority of the pipes could be removed by conventional open trenching techniques the crossings of the north and south bound carriageways had to be completed. Under normal circumstances this would not be an issue but the asbestos regulations required UEA to ensure no dust or fibre particles entered the atmosphere.
On previous sewer contracts UEA had up-sized existing mains using its thrust boring equipment. A specially designed cutter head had been designed that would follow the existing pipes and then install a steel case into which a new carrier pipe was installed and grouted. This option was presented to the client and after reviews of the proposed work method statements the process was adopted as the preferred installation method. UEA manufactured the required cutter heads with the guides for the existing pipelines – the only constraint being that all excavated and augured material had to be removed, bagged and sealed by an authorised asbestos removal company.
To undertake this project UEA used its 160 tonne auger boring machine. Bore one was a 12 metre shot of 450mm steel case into which a 300mm reinforced concrete pipe was installed. The launch pit had to be totally encapsulated so the air quality could be monitored for asbestos particles. UEA used a water spray throughout the auger process to settle any dust. All material was hand shovelled into 44 gallon containers and sealed before removal from site. The same processes were followed for bores two and three -both 900mm steel case for a total of 54 metres.
For more information about this project or UEA Trenchless, please send enquiries to Steven Hopkins.