New South Wales
Sydney Water is undertaking another sewerage project, the Upper Blue Mountains Sewerage Scheme, which has involved a 2.4 km underground pipe being pushed through Australia’s longest bore – from Medlow Bath to the existing sewage tunnel at North Katoomba – in July 2007.
Using horizontal directional drilling to connect the new section of pipe to the existing sewage tunnel, the world heritage area was protected during the project and some significant engineering challenges were faced, including boring under the Cascade Dam and the water table.
Another Sydney Water sewerage scheme involving the use of Trenchless Technology is SewerFix, an extensive program to improve Sydney’s sewerage system, reduce the number of sewage overflows reaching waterways and protect public health, which will run until 2010.Article continues below…
The Liverpool to Ashfield pipeline has involved extensive boring, with the 24 km long pipeline running from Liverpool Sewage Treatment Plant (STP) to an existing sewer at Ashfield.
Also, the Mount Kuring-gai Industrial Estate Sewerage Scheme – which involves the installation of a network of reticulation pipes and the transfer of wastewater to the Hornsby Heights Sewage Treatment Plant, as well as small diameter pipes to homes – will use underground boring techniques where open trenching is not appropriate, to minimise disturbance and the extent of restoration required.
There are also water projects in Sydney making use of various Trenchless Technologies. Water main renewal projects across the city utilising sliplining and pipecracking are ongoing, to replace aged or damaged water mains in Sydney Water’s network.
Sydney Water also plans to construct a 250 million litre of water a day desalination plant, for which a pipeline will be constructed. Community impacts along the desalination pipeline route will be minimised as much as possible by using trenchless construction methods, such as microtunnelling. The plant is scheduled for completion in 2009-10.
Aside from water, electrical and communications continue to be installed by trenchless techniques around the state with projects like the Wisemans Ferry which saw the installation by HDD of an 11 kV cable from the Wisemans Ferry side of the Hawkesbury River across to the river’s northern side and various communications conduit installations by boring and small HDD.
SA Water owns and manages over 8,000 km of sewer mains throughout SA with sizes up 2,600 mm and some dating back to the 1880s. In 2002, a risk assessment model was developed to manage these assets. Trenchless Technology is a vital component on the ongoing sewer management strategy, with, for example, a comprehensive, prioritised 5 year program of CCTV inspection of the pipe systems, which began in June 2004. The work will be done using the latest equipment, digital recording and classification in accordance with the new WSSA Sewer Inspection Reporting Code. During 2007, SA Water undertook the CCTV of approximately 57 km of sewer mains.
Furthermore, a rehabilitation strategy has been developed for the assets at greatest risk, such as large diameter concrete mains installed prior to 1939. A 10 year relining program commenced in early 2004.
SA Water is also developing an overflow abatement program. Trenchless Technologies will be increasing used in the cleaning and rehabilitation of the smaller diameter mains that are the major cause of overflows.
As part of sewer extensions in the Adelaide Hills, directional drilling has been used for both sewer pumping and gravity sewers using a variety of locally based contractors. Pipe diameters are at the smaller end of the HDPE range and generally less than 100 m in length.
During 2007, SA Water relined approximately 8 km of wastewater mains, primarily RCRJ gravity mains, ranging in size from 225 to 525 mm diameter. Ribloc spiral wound liners were used for all of this work.
Horizontal directional drilling (HDD) of several small diameter sewer pumping mains was undertaken as part of the Adelaide Hills Backlog Sewers asset program through undulating easements. This work was undertaken by SA Directional Boring Pty Ltd.
SA Water has several potential applications of Trenchless Technology planned for the short-medium term on sewer assets, including continued rehabilitation of poor condition sewer mains identified through the CCTV program, and the lining of sewer mains prone to groundwater intrusion as a result of poor condition joints and/or root intrusion in combination with high water tables.
For SA Water’s water networks, the key issues of relevance to Trenchless Technology is the provision of filtered water to small River Murray townships and the rehabilitation of old, large diameter trunk mains.
SA Water has also performed a risk assessment on all of SA Water’s trunk mains to identify those mains that present various levels of risk to SA Water. These mains have been flagged for possible rehabilitation through the application of Trenchless Technology.
The application of Trenchless Technology within the last year includes:
* Minor HDD/bore works on various projects for road or railway crossings. * The installation of a filtered water pipeline across the River Murray from Tailem Bend to Jervois is due for completion in the 2007/08 financial year. This will require approximately 560 m of 355 mm diameter HDPE pipe using HDD to traverse under the River Murray. * The application of Swiftpipe plough in technology for the installation of approximately 8.25 km of HDPE water main ranging in size from 63 mm to 125 mm and lengths from 950 m to 2,600 m.
The largest swagelining project to be undertaken in Australia was completed in mid-2007 for the South Parklands Adelaide CBD Watermain Rehabilitation Project, owned by SA Water. The project involved the rehabilitation of 1 km of DN600 cast iron watermain in an environmentally sensitive location using the technique of swagelining in four 250 m sections and was undertaken by CLM.
Trenchless Technology will most likely be used by SA Water in the future for condition assessment on large diameter, unprotected (eg. no cathodic protection) mild steel trunk mains within metropolitan Adelaide, identified as presenting the highest potential risk to SA Water, and the rehabilitation of these trunk mains post-condition assessment if the assessment deems rehabilitation necessary.
Other South Australian companies have also utilised Trenchless Technology, with Bore-Tech (SA) Pty Ltd having installed several HDPE pipes of 180 mm diameter in Newport Quays (Port Adelaide) area below the water table. As part of this project sewers had to be installed to grade. Bore-Tech has also installed several small diameter HDPE pipes for small developments, road crossings, under existing structures and properties, and has installed a 400 mm steel sleeve under a main road near Loxton.
Rib Loc Australia Pty Ltd has also been involved in a number of recent projects executed in Adelaide by Interflow using the Expanda Pipe system.
For South Australian Trenchless Pipelaying Contractors, work completed over the past year has been primarily for Telstra cabling and the private industry in South Australia.
Trenchless Technology in Victoria continued to grow throughout 2007. The prolonged drought has raised the profile of the water industry in general and investment in infrastructure as a result will continue to increase in the foreseeable future.
As part of this increased investment, projects are increasingly seeing trenchless options raised as viable alternatives to traditional construction techniques. Many trenchless methods – such as sewer relining and directional drilling – are now considered mainstream and are no longer ‘new methods’.
In the Victorian water industry, renewal projects including sewer rehabilitation continue to be predominantly undertaken via trenchless methods such as sliplining and pipe bursting.
Authorities in Victoria are spending in excess of $25 million per annum on trenchless sewer rehabilitation mainly in the diameter range 150 mm to 900 mm.
Water main renewals using pipe bursting have grown especially as this technique becomes more established for routine renewals. In metropolitan Melbourne between 80 per cent and 90 per cent of water main renewals are undertaken in this way, especially in reticulation diameters of 100 mm to 225 mm.
However, in regional Victoria there is a large variation from authority to authority. More often, regional authorities are investigating trenchless and semi-trenchless options. It is expected that growth in trenchless methods will continue.
A number of large water main renewal projects were undertaken during 2007 in inner urban areas by a number of techniques ranging from microtunnelling, sliplining and pipe bursting. Larger projects using these techniques will continue in 2008 due to the costs of reinstating other infrastructure and private property associated with open cut techniques.
The current increase in infrastructure investment has seen an increase in large tunnelling projects to extend major trunk sewers. One such example is the Northern Sewerage Project, to connect Yarra Valley Water’s sewerage system near the Merri Creek at Coburg and the Moonee Ponds Creek in Pascoe Vale to Melbourne Water’s North Western Sewer in Essendon. Projects of this type have necessitated the creation of joint ventures and alliances to enable deliver of these large projects.
Over the last 18 months, trenchless jobs in the state have included approximately 8 km of CIPP lining by Tasmanian-based company UAS, which also reports the significant exporting of technology, CCTV and linings to the mainland.
A total of approximately 60 km of HDD with PE insertion lining has been another recent use of Trenchless Technology in Tasmania, the vast majority being for the gas network and the remainder for water services and main road service crossings.
Regarding the reformation of the state water and sewerage industry, a Ministerial Water and Sewerage Taskforce has been set up to identify structural and regulatory changes to ensure the sector transitions to long-term sustainability.
Changes are expected to current rules, regulations and ownership of assets, how assets are managed and services delivered in conformance with the National Water Initiative Agreements. The outcomes are expected to produce more transparency and reflect the true cost of service and infrastructure provision. Models being promoted include a state authority or three regional bodies that could be owned by the local councils or state, which may prompt a spin-off in asset creation and reconstruction.
Trenchless Australasia would like to acknowledge the assistance of the ASTT Councillors in compiling this article.
One very important aspect of pipeline installation in Queensland in recent times has been the laying of major infrastructure to distribute water across the southeastern parts of the state. The installation of these networks has involved the use of Trenchless Technology.
With 80 per cent of the state’s population living in Southeast Queensland (2.7 million people) and this figure only expected to grow, without additional water supplies the future, economic growth and quality of life in the area will be severely affected.
The State Government’s response has included new supply strategies such as new storages, desalination and a water grid. The government also plans to respond to the demand side of the equation, with new water efficiency plans, pressure reduction and leakage management across the state water network.
The water grid – which includes the Western Corridor Recycled Water (WCRW) project, Gold Coast Desalination Plant, Southern Regional Water Pipeline (SRWP), Eastern Pipeline Interconnector, Northern Pipeline Interconnector, Northern Regional Pipeline, and various regional water projects – will provide a network of two-way pipelines to connect all major bulk water sources in the region.
As part of the eastern section of the WCRW pipeline over 40 trenchless crossings have been required, with trenchless techniques including auger boring, microtunnelling, tunnel boring and HDD being used. A type of hard rock cutting head called the Robbins Small Boring Unit has been used by contractor Winslow Constructors to bore up to ten road and rail crossings.
Furthermore, Microtunnelling Tunnel Boring Machines (MTBMs) are being utilised on the SRWP to tunnel underneath rivers, through hills and under major roadways. Two Herrenknecht MTBMs are being used on the project, on a wide variety of ground conditions, with the machines best suited for tunnelling through rock.
All of the priority water projects as part of the Southeast Queensland water grid are currently in progress and remain on track for completion by the end of 2008.
The Western Australian economy has been very strong throughout the last year and this has meant continued strong activity in the growth of the Trenchless Technology sector.
The Water Corporation of WA continued to provide works that allow for Trenchless Technology. The Infill Sewerage program, which was commenced by the Water Corporation back in the early 1990s still has a small program of works completed every year (approximately $30 million), and many microtunnelled pipes are installed in backyard and difficult street situations. The Corporation also continued a sewer rehabilitation program (approximately $20 million/annum) for strategic areas of potential failures near the Perth river systems. The two selected panellists, Drilline Pty Ltd and Interflow Pty Ltd, have been rehabilitating areas under various contracts.
The Corporation has also been rehabilitating other small pockets of sewer failures around the Perth area throughout the last year.
Early in 2007, the MetroRail City Project was completed successfully by the contractor, the Leighton Kumagai Joint Venture. The project involved approximately 744 m of twin bored underground rail tunnel under the city of Perth and the rail line is now in operation.
Contractors DJ & MB MacCormick continued to complete several large micro-tunnelling and pipe jacking projects. The Perth Main Sewer project for the Water Corporation of WA was completed in 2007.
During the year, pipe rehabilitation company Premium Pipe Services won a contract with the City of Kalgoorlie-Boulder to reline and pipe burst approximately 1.8 km of sewer pipes by offering a trenchless alternative bid to the originally requested tender to dig up and relay pipes.
The use of CIPP to rehabilitate pipes has expanded amongst several of Perth’s councils who are instigating small programs for rehabilitating drainage pipes, many of which are damaged by root intrusion or materials failure of the host pipe.
The use of directional drilling for the installation of underground power and communications has continued to grow and several large contracts are being completed.
The conversion of pole top power to underground power continues to be completed throughout selected suburbs (mostly by trenchless methods) and it is intended that these programs will be expanded further. Larger companies such as Underground Services Australia continue to specialise and complete many of these types of works as well as the many smaller contractors entering the market.