In preparation for the Commonwealth Games Kembla Watertech has been involved in a variety of Trenchless Technology sewer rehabilitation works. The managing authority for this sewer rehabilitation project in the lead-up to the Commonwealth Games was Melbourne’s City West Water. City West Water is a state owned enterprise that manages water supply and sewerage services for the City of Melbourne and the Western suburbs, delivering water through a 3,615 km network of water mains to approximately 290,000 customers. The majority of Commonwealth Games venues are in City West Water’s area of operation.

Kembla Watertech has a schedule of rates contract with City West Water for the provision of sewer rehabilitation services. Kembla has worked closely with City West Water since 2001 to deliver sewer rehabilitation services ranging from sewer relining, patch repairs and civil repairs.

Project summary

City West Water required approximately 742 metres of 300 mm and 225 mm diameter sewer to be relined prior to Christmas 2005 to ensure that all works in the vicinity of the Commonwealth Games Athletes’ Village were completed prior to security lock down of the area.

The project consisted of 555 m of 300 mm diameter sewer and 187 m of 225 mm diameter sewer. The route followed by the sewer started in the middle of a busy road adjacent to a tram crossing, wound its way through the Royal Melbourne Hospital’s Parkville Campus, around the boundary of Commonwealth Serum Laboratories Limited (CSL), along a creek and steep embankment, through a newly constructed wetlands and ended inside the boundary of the Commonwealth Games Athletes’ Village. The route of the sewer is outlined on the aerial photograph as is the temporary pipeline set up to bypass the sewer flow during lining installation.

A great deal of coordination with all of the stakeholders was necessary to ensure the work proceeded smoothly so that the full advantages of Trenchless Technology could be realised. Some of the issues encountered were trade waste discharges being received into the sewer 24 hours a day, landscaping and tree planting being carried out on the site where work was being undertaken, security fencing being erected, the need to maintain unrestricted access for elderly patients being treated at the Hospital, busy roads which had to be crossed by the sewer bypass pumping lines and safe access to various other authority assets.

Installation

Time was of the essence, but it was just as critical that the work was completed safely and without any environmental incidents. Kembla chose to use its Enviroliner system for this project. Enviroliner is a form of CIPP lining which provides a structurally solid wall lining in long joint free lengths. One of the major practical advantages of the Enviroliner system is the ability to install very long lengths in a single operation. This ability to tailor make the lining length to suit specific site conditions enabled Kembla to choose start and finishing points that provided least risk and least disruption. This project highlighted this benefit where a 320 m length of 300 mm diameter lining was installed through a number of intermediate access chambers in a single 24 hour operation.

The existing sewer flow had to be bypassed during the installation of the liners and this presented the major practical problem. The difficult location of some of the access chambers, the high volume of flow, the need to maintain services to the Hospital and CSL and the crossing of major roads all had to be taken into account. Ultimately, it was decided that two 150 mm diesel suction pumps and twin bypass pipelines each 800 m in length. The chosen route minimised disruption and pre-planning located existing stormwater drains into which the bypass hoses were laid to transfer the flow under a major road without the need to excavate a trench or bypass the traffic. Low noise submersible pumps and eductor trucks were used to ensure the service to the Hospital was maintained at all times without any adverse side effects.

Conclusion

Because of the natural parklands, golf course and high profile location of this project any environmental incident would have been simply unacceptable. Careful risk management planning of the entire installation and bypass procedures resulted in the 742 m of sewer being completely rehabilitated in four days of site work without incident and to the complete satisfaction of the client. This project proved to be a shining example of Trenchless Technology at its best with benefits for both the client and the community.