The difficulty was that the two estates were separated by a lake, a hill and a train storage facility, approximately five train tracks wide, for domestic and interstate trains. To further complicate the situation the project was specified as a 225 mm installation on minimum grade all the way. The total line was approximately 250 m long and the installation was designed with the pipe invert being approximately 4 m below water table. The ground conditions were stated to be sandy silty clays. Alternative solutions were building a new pump station or running the sewer a long distance, both of which were very costly.

Bullseye took on the project to demonstrate the effectiveness of their new vacuum microtunnelling equipment, a vacuum extraction microtunnelling system that has been designed to operate in either self-supporting or non self-supporting ground conditions.

Vacuum microtunnelling equipment has been utilised throughout Australia for over twenty years. Vacuum microtunnelling is known as a cost effective method for installing pipelines in self supporting strata such as silts, clays, reef and hard rock. The flaw of vacuum microtunnelling has always been its ability to work effectively in non self-supporting ground conditions. The new system allows for controlling the flow of material at the face and maintaining a supported hole throughout the installation process.

At the outset of the project Bullseye consulted with Brendan Carmody of Maunsell Australia to change some of the specifications to reduce the total project cost. This job would previously have been done by slurry microtunnelling systems at a minimum size of 300 mm. Slurry microtunnelling would have relied on utilising a rated jacking pipe. Bullseye were able to reduce the cost by reducing the pipe size and by installing a less costly 280 mm OD PE pipe. After assessing the ground condition on site the maximum drive length was broken down to 104 m, as failure was not an option.

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Bullseye successfully completed the project with extreme cost effectiveness. After seeing the effectiveness of this microtunnelling system on site Catcon awarded Bullseye an additional 100 m line crossing over the main highway at Mawson lakes. This line was surveyed upon completion and stated to be accurate to +/- 2 mm over the 100 m length. Nick Karapetsas from Catcon said: “Microtunnelling effectively deleted a pump station and substantial cost out of the venture.”

Bullseye has exclusive use of its revolutionary microtunnelling equipment, which has allowed the company to install small diameter <600 mm pipelines at rates other companies just cannot match. By specialising in small diameters Bullseye has achieved high productivity in a wide range of ground conditions. All of the Bullseye crews are fully mobile and are experienced in microtunnelling and the sub-contract requirements of open cut pipeline companies.

Bullseye offer a range of trenchless equipment and operate at the cutting edge of Trenchless Technology. Their research and development experience in the design aspects of trenchless equipment, and some of their own hybrid machines, mean Bullseye can offer trenchless solutions at efficient prices. Bullseye are happy to be contacted to discuss trenchless options for particular projects.