How easy life would be for the owners and operators of underground pipe assets if their pipes didn’t corrode or crack, if they were laid straight and never moved and if external load and operating conditions never changed. In practice this is not the case, and engineers and field staff are faced daily with the issue of extending the service life of their ageing pipe assets. The cost of maintaining these assets is increasing in line with their age.

Established back in 1892 as The Hunter District Water and Sewerage Board, Hunter Water Corporation (HWC) as it is now known is a statutory state owned corporation providing water and wastewater services to almost half a million people from five local government areas – Newcastle, Lake Macquarie, Maitland, Cessnock and Port Stephens.

HWC’s vision is “Caring for our Community and the Environment” and in line with this vision HWC have embraced Trenchless Technology as the most cost effective and least disruptive answer to the rehabilitation of their ageing underground assets. For any newcomers - pipeline renovation involves restoring the performance of a length of pipe by using the existing conduit i.e. it uses the existing hole in the ground. When the pipeline renovation is carried out without the need for excavation it is called Trenchless Technology.

There are now available in Australia a range of Trenchless Technologies for both sewer and water mains. Some of these techniques involve short length spot repairs while others are capable of lining over 300 m of pipe in a single installation.

Kembla Watertech P/L is a specialist pipeline rehabilitation contractor who has been a leader in this field since 1993. Kembla now has a team of over 150 experienced and trained personnel who employ state of the art proven Trenchless Technology systems from around the world.

Numerous projects have been completed for major authorities and other clients throughout Australia and the total length of linings installed by the company now exceeds 500 km.

HWC has been employing Trenchless Technology since the mid ‘80s by calling open tenders at different times for various amounts of work. Kembla has been awarded a number of these tenders.

Calling a number of separate tenders every year is time consuming and costly and Peter Nikolic, Contract Manager for HWC, says that “the Corporation identified a number of advantages in switching to a term contract for sewer rehabilitation. These included; reduced tendering and administration costs, more efficient project management, economies of scale and better community relations as a result of developing a long term relationship with the right contractor.”

In October 2004 HWC called tenders for Term Contract CG323206, Rehabilitation of Sewermains by Lining and Associated Works. The initial contract period would be for two years with a two year option to extend. Work would be issued in three different categories:

• I/I Reduction works: Approximately 10km in first year and 8 km in second; • HWC’s Critical Sewer Programme: Approximately 0.5 km monthly based on CCTV inspections of critical sewers; and, • Reactive Emergency Works: Sewer lengths will be selected from customer complaints and daily operational problems.

Kembla Watertech was subsequently awarded the contract and the programme of work has commenced. Kembla’s commitment to caring for the community has already seen the establishment of a local facility in Newcastle with local employment opportunities.

Caring for the Environment

One of the critical sewers identified for rehabilitation in the initial period of this term contract is 1800 m of 300 mm sewer main which runs below sea level along a section of the foreshore of Lake Macquarie at Coal Point. This main is in a serious deteriorated condition and any sewage spill into the pristine recreational waters of Lake Macquarie would be environmentally intolerable.

Kembla has the ability to install a solid wall structural lining in long continuous lengths of up to 300 m using only existing access chambers. Thus, this work can be planned to use those access chambers most easily accessible and least disruptive (see photo to the right). House service lines will be reinstated after lining using specialised remotely controlled robotic cutters and CCTV camera. No excavations are required and as each lining installation is completed within 24 hours any disruption to the community and the environment is minimal.

The Kembla linings are designed to provide a minimum of 50 years life and the smooth joint free nature of the lining not only eliminates potential leaks but also provides increased hydraulic flow characteristics to the rehabilitated sewer. The environment is well and truly protected.

Conclusion

Utilities, small and large alike, are now more than ever under the spotlight to operate in an efficient, safe and environmentally conscious manner. The forces of competition, increased customer focus, quality assurance and productivity improvements all influence the commercial manner in which these authorities are managed. This long term contract between Hunter Water Corporation and Kembla Watertech P/L will be a key element of the Corporation’s mission statement: Continuous improvement in being commercially successful while delivering value-for-money water, wastewater and associated services in an environmentally responsible way.

Reference; 1. “International Trends in the Application of Trenchless Technology for Pipeline installation and Refurbishment”: Menno Henneveld. Paper presented at Pipes Wagga Wagga 2001.