Trenchless Technology in Australia and New Zealand
The International surge in the development and application of trenchless technology has had an impact in Australia and New Zealand. The problems of maintaining aging pipe infrastructure is highlighted by the knowledge that there are some 130,000 kilometres of water mains and 80,000 kilometres of sewers and sewerage pumping mains in Australia.
A significant proportion of these have exceeded, or are approaching, their design life. Conservative estimates would indicate annual replacement costs of over $200M, with an increasing awareness of the favourable economics of renovating, or maintaining an already expensive hole-in-the-ground. These statistics do not take into account gas distribution systems, electricity mains and telecommunications which service areas with similar asset management issues.
Australia has had a long history of conventional pipe-cracking, horizontal boring and pipe-bursting, and continues to use such techniques with success. Pipe rehabilitation and renovation has also had a history of some thirty years in Australia. Recent studies have shown that there are now some 50 different rehabilitation methodologies and a similar number of trenchless installation methods in Australia and New Zealand.
Australia and New Zealand have unique problems of geographic spread and a great potential for a fragmented approach to the development and implementation of trenchless technology. In recognition of these difficulties, and as a result of the promotion of developments of trenchless technology through international No-Dig events conducted by International Society for Trenchless Technology (ISTT), the Australasian Society for Trenchless Technology (ASTT) was formally established in March 1991 and became affiliated with the International Society for Trenchless Technology in April 1991.
WHAT IS TRENCHLESS TECHNOLOGY?
What is trenchless technology? Nearly all of these service organisations have a huge investment in underground pipelines, cables and conduits. Each has a particular interest in installing new pipelines at minimum cost. There is also an increasing awareness of the favourable economics of renovating or maintaining an already expensive 'hole-in-the-ground'.
Many of these services require conduits too small for man entry and conventional tunnelling techniques are not applicable. Pipelines up to a metre in diameter represent some 99% of all underground pipeline infrastructure. Traditional open-cut excavation methods for installing, renovating or maintaining services are often disruptive and uneconomical, and the true social costs and environmental impact of such disruption is not taken into account. This has resulted in an ever increasing demand for methods of pipeline installation and refurbishment which have the capability of performing this work without the need for trenching. The techniques which have been developed for this purpose are known as 'no-dig' or trenchless technology.
TRENCHLESS TECHNOLOGY SYSTEMS
Trenchless technology systems utilised on underground pipelines fall into three broad categories:
- Installation of new pipelines and services
- On-line replacement of existing pipelines
- Renovation of existing pipelines.
To support these systems, a number of essential services are required before trenchless technology can be applied. These include:
- Site investigation - locate existing services and ground conditions
- Condition surveys - closed circuit TV and robotics are now commonplace
- Location surveys and mapping thermal imagery and ground mapping radar being used.
The potential use and application of trenchless technology in Australia and New Zealand is staggering. In the water industry alone, it is estimated there are some 150,000 km of water mains and 96,000 km of sewer and sewerage pumping mains. A significant proportion of these have exceeded, or are approaching, their design life. Conservative estimates would indicate annual replacement costs of $200 million, with an increasing awareness of the favourable economics of renovating or maintaining an already expensive hole-in-the-ground.
The full deregulation of the Telecommunications Industry in Australia on 1 July, 1997 has resulted in some 4,500 km of new cable network installation, with trenchiess technology playing a major role in these installations. The use of directional drilling and guided boring provided cost savings of some 35% compared to open cut installation.
In Western Australia, pilot projects are underway to test the feasibility of placing underground the electricity system which is currently on overhead lines. The transferring of the whole system underground is estimated to cost around $2.4 billion. A projected programme recently announced suggested that 50% of the System would be underground by the year 2010.
The success of trenchless technology on similar projects in Australia and New Zealand would suggest there is a real role for the technology on these, and many other Programmes.
APPLICATION OF TRENCHLESS TECHNOLOGY IN AUSTRALIA AND NEW ZEALAND
There are many initiatives underway to assist in the continued introduction of trenchless technology in Australia and New Zealand. Recent studies have shown there are more than 60 proprietary products and methodologies used for the trenchless repair and renovation of pipelines in Australia and New Zealand. These are being used by more than 70 utilities experienced in the use of these methods. There is also an appreciable increase in the construction and installation capability using trenchless technology. It has been estimated there were some 70 guided boring machines utilised in the telecommunications industry alone during the network run-out.
The continual growth in the application of trenchless technology will require an understanding of what the current and future technology in Australia and New Zealand has to offer.
Planners need to understand the opportunities that the alternative trenchless technologies have to offer. Designers must design with the knowledge that a wide range of trenchless techniques and technologies are already available - with continuing economic advantages. Likewise, with trenchless installation, refurbishment and rehabilitation techniques, a wide range of social, technical and economic advantages will also be readily available.
High level strategies within the utilities to utilise the available technology must be encouraged. This implies developing an understanding of the value of the application of the technology, and linking this closely with asset management strategies already in place. Once there is a greater awareness of the impressive state of development that the trenchless technology industry has achieved when advantage is taken of the range of techniques, equipment and materials that already exist; and when the traffic authorities and utilities recognise the need for, and advantages of trenchless technology, then the true potential of no-dig techniques will start to be realised.