The scheme involved the upsizing of the existing sewer network within the community of Blackheath. The objective of the project was to increase the hydraulic capacity of the pipeline to alleviate flow problems as a result of the increasing population and future sub-division within the area.

Pipe bursting is one of the few Trenchless Technologies to provide a completely new pipe without being influenced by host pipe conditions. Pipe bursting typically includes renewal of all services and connections, ensuring a service life consistent with a new pipe installation upon completion. CLM Trenchless has been providing pipe bursting for the trenchless renewal of water, sewer, stormwater and industrial pipelines in Australia for over 17 years.

One of the advantages of pipe bursting is the ability to upsize the host pipe. The degree of upsize is primarily limited by surrounding soil conditions, depth and proximity of other services. Besides Sydney Water, recent work has been performed for a number of other clients in South Australia, Victoria, New South Wales and Queensland.

Project profile

The completion of the Upper Blue Mountains Sewerage Scheme will provide an improved sewerage service to the urban areas of Mount Victoria, Blackheath and Medlow Bath. Benefits of the scheme include an improvement to water quality in local creeks and streams and a reduced risk to public health from poorly performing septic tanks.

As part of the overall project, new pipes will be installed and some existing sewage pipes in Blackheath will be amplified to ensure system capacity into the future. One of the key considerations when Sydney Water was deciding on the preferred technology for the upsizing was the environmentally sensitive area where work was to be undertaken. CLM was awarded the project in February 2008 based on key assessment criteria of experience, technical expertise and methodology.

This project involved the upsize replacement of two sections of the sewer main in an area of bushland in Blackheath earmarked for a new housing subdivision. A track had to be cut on the side of a hill in order to undertake the construction work, so a number of environmental safeguards had to be put in place.

A pneumatic pipe bursting approach with a 10 tonne winch was used, which providing both the constant tension as well as guiding the pipe bursting tool. The two sections were upsized from 150 mm to 225mm, and 225 mm to 300 mm respectively. The construction of manholes was also required.

Besides the environmental sensitivities, care also needed to be taken with the local community given CLM was working in backyards reinstating a number of service connections. The new pipeline was constructed of HDPE pipe and service connections were HDPE electro-fusion saddles, with back to boundary service connections laid in PVC.

This project was an excellent example of how pipe bursting provided an improved pipeline capacity without having to completely excavate the pipe route. CLM Trenchless routinely provides upsizing projects for various water authorities and developers.