Pipe jacks storming ahead in Queensland

Pipe jacks storming ahead in Queensland

In late 2007, TBA completed 10 pipe jacked tunnels on behalf of the Western Pipeline Alliance (McConnell Dowell, Abigroup & GHD) totalling 249 m of 1,800 mm diameter and 120 m of 1,500 mm diameter pipe jacked tunnels. The alliance was constructing a pipeline between Bundamba & Caboonbah in south east Queensland to supply recycled water to Tarong Power Station and Wivenhoe Dam to supplement drinking supplies, which is part of the Queensland Government massive $A10 billion South East Queensland Water grid response to the drought.

Early this year TBA was awarded the contract by the Safelink alliance to install four pipe jacked stormwater tunnels under the Centenary Highway as part of the $A1 billion Ipswich Motorway upgrade project – Wacol to Darra in southeast Queensland. The Safelink Alliance consists of the Department of Main roads, Leighton Contractors, BMD Constructions, Arup & Maunsell AECOM.

In addition to the installation of three 57 m long 2,100 mm diameter and one 65m long 1,800 mm diameter stormwater pipe jacked tunnels, TBA’s scope of work included design assistance and construction of the pit and thrust walls for the 2,100 mm diameter tunnels. These tunnels can be seen in figures 1, 2 and 3.

The construction of the pit and thrust walls was achieved in complicated ground conditions, which required 24 hours of pit dewatering. Each of the tunnels was completed in approximately 10 working days and due to the ground conditions, an intermediate jacking station was utilised on each of the tunnels.

In June this year, TBA also completed 194 m of 1,350 mm diameter stormwater tunnel for Pine Rivers Shire Council, Queensland. The tunnel was completed from one launch pit, jacking 32 m in one direction and then moving the rig 180 degrees, 154 m were jacked with the remaining 8 m being laid in the pit.

TBA is currently working for the Queensland Department of Main Roads in a major project, which involves the culvert replacement beneath the Gateway Arterial and Bracken Ridge Road in Brisbane. Corrosion due to standing water has caused a loss of steel sections in the culvert walls and due to structural failure and danger of sudden collapse, the repair of the culvert was considered a very high priority. The culvert consists of thee helical steel pipes – 1,950 mm, 1,800 mm and 1,650 mm, each 190 m long.

The repair methodology by cutting the existing steel pipes and immediate replacement by reinforced concrete jacking pipes (RCJP) proposed by TBA was accepted by the Department of Main Roads and the slow replacement process began towards the end of last year.

For this particular project, TBA designed and custom built a steel pipe cutting tractor (figures 4 and 5), capable of entering the damaged pipelines and cutting segments not longer than 200 mm. The 1,950 mm and 1,800 mm helical pipes are being replaced with 2,100 mm diameter RCJP and the 1,650 mm helical pipe is being replaced by 1,950 mm diameter RCJP. Throughout the project, additional measures of securing the roads such as horizontal grouting and resurfacing were undertaken by the Department of Main Roads. At present, TBA is working on the third and final pipe replacement with completion expected around September of this year.

Cable installation and culvert replacement in NSW

Towards the end of last year, TBA was awarded the contract to install 120 m of 2,400 mm diameter cable tunnel as part of Energy Australia’s new 132 kV/11 kV Kogarah substation in Sydney. The objective of the project was to design and construct a pipe jacked tunnel beneath the rail corridor and between the Carlton Substation and the new Kogarah Substation, to cater for a total of two 132 kV feeder circuits and up to twenty-six 11 kV feeders.

The overall project was awarded to Abergeldie Constructions, who in turn awarded the pipe jacking part of the contract to TBA. For this project, TBA manufactured the 2.668 m OD diameter rotating head shield and pipe jacking rig in its factory in Oxley, Queensland, as shown in figures 6 and 7.

The pipe jacking installation of the 120 m tunnel took 35 days to complete through Sydney’s sandstone. The receiving pit in this particular project was the basement of the new Kogarah substation (figure 8) and TBA was able to achieve the very strict requirements for both time and final position of the tunnel, which deviated only 10 mm from the original tunnel design.

TBA was also involved in the replacement of another culvert near Somersby for the New South Wales Road Traffic Authority beneath the F3 where the current culvert is substituted with a totally new stormwater pipe jacked tunnel. The tunnel is 86 m long and is constructed using class 6 – 1,500 mm diameter J-series Humes pipes. TBA has undertaken to commence tunnelling from the unconventional higher end of the tunnel at a grade of 6 per cent, which was a result of the site specific conditions. The pipe was completed after only 20 days in mid-July.

A centenary of service rewarded with Trenchless Technology

The MMSR is a major urban infrastructure project that will replace a section of Melbourne’s main sewer that has been servicing the city and inner southern suburbs for over 100 years.

The MMSR will be using a LOVAT tunnel boring machine (TBM) to excavate the pipeline, ensuring that much of the necessary activity can take place underground.

The estimated total coat of the project will be $220 million, which will be funded by the Victorian State Government.

MMSR project scope

The original Melbourne main sewer was built between 1894 and 1897. Melbourne Water said that the old sewer requires replacing, due to its age and capacity, to keep up with urban growth. The capacity of the new sewer will be four times greater then the existing sewer.

Construction work for the MMSR will include the replacement of approximately 2.214 km of the existing Melbourne main sewer from the Docklands in the north to connect with the Hobsons Bay main sewer in Port Melbourne. The diameter of the replacement sewer tunnel will be between 1.5 – 1.8 m at a depth of between 10 – 15 m.

The MMSR will also involve the removal of the North Wharf pump station and a staged sheet piling process for the Yarra River.

TBM

The TBM will be a specially designed earth pressure balance machine of 2.952 metres in diameter to construct a 2.4 metre ID segmental tunnel lining. The TBM will have an 11 metre shield length and measure 92 metres in total length, including backup. The TBM is being designed to be capable of cutting a maximum of 150 mm per minute.

Six vertical access shafts 10 – 15 m deep will be excavated along the sewer corridor providing access for the TBM to be inserted and retrieved. These shafts will then act as future manholes.

The TBM will bore into the ground at the key construction site of Fennel Reserve in Port Melbourne. It will first head south to the Swallow Street shaft where it will be removed and then re-inserted at Fennell Reserve shaft to then tunnel north to the South Wharf shaft on the bank of the Yarra River. Earth spoil from the tunnelling operations will be removed at the Fennell Reserve shaft.

The northern section of the project, around Docklands and the Charles Grimes Bridge, will use pipe jacking technology.

Contractors

John Holland Group has been appointed lead contractor for the project on behalf of Melbourne Water. Other project team members include designer GHD and project manager Connell Wagner.

John Holland managing director David Stewart said “This is the second project to reach the construction stage under John Holland’s six year agreement with Melbourne Water to provide tunnel construction services. We are excited about getting started on this vital piece of Melbourne infrastructure.”

The TBM will be purchased from Canadian company LOVAT. The machinery will take approximately nine months to manufacture, the delivery of the TBM is expected in early 2009.

The Yarra River crossing

Melbourne Water has identified a major component of the MMSR to be the crossing of the Yarra River, upstream from the Charles Grimes Bridge.

The river crossing will be completed by a three stage cofferdam construction, commencing from the south bank and progressing north. The company said that this will ensure two-thirds of the river will remain open to traffic at all times.

The cofferdam construction involves the installation of steel sheet piling to create a closed area in which to work. Some river silt will be removed to allow concrete pipes to be laid under the river bed. Once the silt has been removed, a concrete slab will be poured within the sheet piling as a base upon which a pipe will be laid and fitted together by divers. The pipe will then be encased in concrete, secured into place and back filled to the existing river bed level. The sheet piling arrangement will then be moved further across the river to allow the next stage to be laid.

Melbourne Water said that strict environmental controls in accordance with the Environmental Protection Association of Victoria, Melbourne Water and Parks Victoria requirements will be implemented and maintained throughout the duration of the project to protect the health of the waterways and aquatic life.

Branch sewers

The MMSR project will also involve the construction of approximately 2.5 km of new local branch and reticulation sewers to connect the existing sewer system into the new MMSR. The company said that these works will be undertaken mostly by Trenchless Technology using small diameter pipes between 300 – 500 mm. Small short term shaft sites in local streets will be utilised to complete the works.

Challenges

Melbourne Water has identified a number of interesting challenges presented by the construction of the MMSR. These challenges include working in highly developed urban areas and the multiple major construction projects occurring at the same time, such as the Melbourne Convention Centre and the M1 freeway upgrade. Finally, the crossing of the Yarra River using the staged cofferdam construction will test the ingenuity of the contractors.

Construction begins

Melbourne Water said that construction will begin in August and is expected to be completed by early 2012. The project team will continue to work closely with local residents, community groups and other key stakeholders including the City of Melbourne, City of Port Phillip, VicRoads and Parks Victoria to minimise the potential impacts and ensure regulatory requirements are met.

Microtunnelling Christchurch’s Ocean Outfall Pipeline

The $NZ85 million project comprises a new pump station and 5 km of 1,800 mm diameter pipeline with a design capacity of 6 cubic metres per second. The pipeline comprises 2.3 km of concrete pipe installed by microtunnelling and 2.7 km of polyethylene (PE) marine pipe installed by dredge and lay.

Project background

Sewage is collected in a dedicated network that terminates at the Christchurch Wastewater Treatment Plant, where primary and secondary treatment is undertaken. After the main pathogen reduction has occurred the wastewater is currently discharged into the Avon-Heathcote estuary, where it flows out to the coastal area of Pegasus Bay.

The community had significant reservations about wastewater discharging into the Avon-Heathcote estuary, as recreational water quality in the estuary was not being met at all times. It was decided that an ocean outfall to discharge 3 km offshore would be the best solution to rectify the problem. Consent for the project was granted in November 2005, with a requirement for the project to be operational by 30 September 2009.

Pipeline contract

The contract awarded was split into the “÷land-based’ pipeline section and the marine pipeline section. The land-based section of pipeline comprised an 874 m drive beneath the Avon-Heathcote estuary to a pump station, a 604 m drive through South New Brighton Park and along Jellicoe Street to the sand dunes, and a 830 m drive from the sand dunes to a point about 600 m offshore, beyond the surf zone. The land-based pipeline will connect to the marine pipeline at this point beyond the surf zone, where the depth of water at low tide is approximately 6.5 m and the cover to the pipeline is about 3 m.

The successful tender from McConnell Dowell Constructors comprised approximately 2,300 m of 1,800 mm ID concrete jacking pipe being installed in three drives from the pump station and connecting with the marine pipeline section at the point beyond the surf zone offshore. The microtunnel boring machine (MTBM) would be recovered using a “÷wet’ marine recovery technique from a barge.

Site investigations and pipeline design

Site investigations, hydraulic analysis and pipeline detailed design were carried out by URS.

The site is located within a marginal marine setting, with the project corridor crossing estuarine, dune, beach and shallow marine environments. Investigations were undertaken to collect information required for the design of excavations along the pipeline route and at three proposed shaft locations. The onshore investigation comprised of test pits, cone penetrometer tests, piezocone penetration tests with dissipation tests, dual tube push sample holes, dynamic cone penetrometer tests, laboratory testing, water level monitoring and chemical analysis of water samples.

The subsurface investigations indicated that four distinct geological materials were present along the pipeline route. The microtunnel pipeline was expected to lie within a zone defined as dense to very dense, uniform fine beach and dune sands, with some thin medium dense fine sand or silty sand lenses. Some shell layers were also expected.

Pipeline design

Three locations were identified for microtunnel shafts: at the pump station interface, in South New Brighton Park and in the sand dunes.

The vertical alignment of the overall pipeline was governed by the minimum depth of cover requirement at the diffusers and minimum cover of the microtunnel pipeline beneath the deepest section of the estuary. Depth of cover through the majority of the microtunnel section is approximately 8 – 9 m, however a minimum cover of two pipe diameters or about 4.2 m was chosen beneath the estuary to ensure that adequate face stability and alignment control of the MTBM could be maintained should soft sediments be encountered.

Rubber ring jointed reinforced concrete (RRJRC) jacking pipes were specified. With jacking forces tending to govern the pipe structural design, the contractor was responsible for the design of the pipe and jointing system within the following limits to satisfy the hydraulic design:

  • Pipe internal diameter: 1,740 mm – 1,800 mm,
  • maximum working pressure: 290 kPa,
  • factory test pressure: 420 kPa (subsequently reduced to 370 kPa due to larger pipe size), and
  • corrosion protection: 35 mm external cover for marine conditions. Internal lining was not deemed necessary because of the high quality of the treated wastewater and lack of potential for sulphide attack
  • .


Settlement monitoring

Excessive settlement for the microtunnel drive from Jellicoe Street had the potential to damage existing sewer pipeline, water supply services, residential property and be a hazard to public and traffic. The cover along Jellicoe Street varied from about 9 – 11 m. The existing 150 mm diameter concrete sewer is buried about 1.5 m below the road surface directly above the microtunnel pipeline, with laterals at each property.

Given the potential to damage the existing sewer or property, the contractor was required to implement a settlement monitoring program with readings taken prior to, during and after the MTBM passes defined monitoring points along the street.

Settlement thresholds were set at 12 mm on centreline, 6 mm at 5 m off centreline and 3 mm at 10 m off centreline, which if exceeded, triggered an increase in monitoring frequency and a corrective action plan. These threshold levels were never triggered.

Construction of the microtunnel sections

The 2,308 m of tunnel was split into three drives:

  • Drive 1 – 874 m from the pump station at Construction Management Area 1 (CMA1) to the park (CMA2),
  • Drive 2 – 604 m from the park to the beach (CMA3) beneath Jellicoe Street, and
  • Drive 3 – 830 m from the beach through the surf zone and out to the connection point offshore with the dredge and lay marine pipeline.

The drives were all straight, with a down gradient of 0.3 per cent from the pump station. At the park shaft at CMA2, there is a 30 degree change in direction.

CMA2 was selected as the main site staging area, and this site was used as the launch shaft for Drives 1 and 2, necessitating the turning of the jacking rig.

Shaft construction

The shafts were all constructed as sheet piled pits, with CMA1 and CMA3 shafts being rectangular 6 m x 12 m shafts, while CMA2 was a circular shaft, 15 m in diameter. Sheet pile types AZ34 or AZ36 with a length of 24 m were used for the shafts.

The CMA1 shaft was constructed adjacent to a large sheeted pit excavated for the pump station construction, where well points were used to dewater the excavation. The shaft excavation therefore had to be dewatered and constructed in the dry to avoid any adverse effects on the adjacent works.

The CMA2 and CMA3 shafts were constructed partially “÷in the wet.’ They were initially excavated in the dry using a sump pump to lower the water table to about 8 m depth and walers fitted before being allowed to flood, with the remaining excavation being carried out with a clamshell grab. Final excavation trimming was carried out by divers using airlift equipment, the divers then coordinated the placement of prefabricated reinforcement cages and tremie poured concrete for the base slab. The shaft was then able to be pumped out with the minor leakage remaining being within the capacity of a small sump pump.

Wet recovery of the MTBM

For Drive 3, McConnell Dowell has chosen to recover the MTBM using a “÷wet’ recovery method rather than constructing a recovery shaft. To achieve this, the MTBM has been driven through to the recovery point where cover to the seabed is approximately 3 m.

Following completion of all disestablishment, cleanup and pressure testing of the concrete pipeline, which will be done with the MTBM still in place, the dredge will then excavate around the MTBM and buoyancy tanks will be fitted.

A wet recovery bulkhead door will be sealed at the back of the MTBM, which, after the flooding of the pipeline, will then be jacked free of the pipe and floated to the surface for recovery.

Once the MTBM has been removed, a specially designed mating piece will be installed by divers, to make the connection between the RRJRC jacking pipes and the PE marine pipeline.

Bentonite lubrication system and intermediate jacking stations

The slurry MTBM utilised a closed circuit slurry circulation and muck separation system located on the surface. It comprised a number of slurry tanks, which were dosed with bentonite and pumped to the MTBM cutterhead, providing face support and a means of transporting excavated material to the surface for removal. The slurry was transferred between the MTBM and separation plant through 150 mm diameter pipes and slurry pumps.

As the three tunnel drives were relatively long at 874 m, 604 m and 809 m respectively, the minimisation of jacking forces was of paramount importance.

In addition to mixing/holding tank/pumping system for bentonite production and delivery, a PLC controlled automatic injection control system regulated the cyclical injection of lubricant into injection nozzles positioned along the pipeline. During the jacking operation the bentonite fluid was injected into each nozzle for a fixed time, following which injection shifted to the next nozzle in sequence. In this way the pipeline was surrounded by lubricating fluid. Rate of injection was adjusted relative to the advance rate such that the theoretical annulus was filled.

As a contingency measure, intermediate jacking stations, comprising 14 hydraulic cylinders each capable of exerting a push force of 72 tonnes were installed at approximate 110 m spacing.

Intermediate jacking stations were installed in each drive every 115 m to provide the ability to jack separate sections of the pipeline in the event that jacking loads became too high. These did not need to be activated for Drives 1 and 2, but up to three of the intermediate stations were activated in Drive 3.

Drive 1 construction

The 874 m push across the estuary commenced on 23 May 2007 with the MTBM pushing through the tunnel eye in the CMA2 shaft. Over the first 200 to 300 m of drive some variable ground conditions were encountered that resulted in difficult driving and variable progress. The variable ground conditions encountered included shell formations, cobbles and timber. Most of the timber encountered came through the slurry system as finger-sized rounded fragments which, like the shells, probably originated from the 6,500 year old beach formation.

There were some instances where larger fragments of timber had been chewed by the cutterhead, and the cutterhead also jammed on a number of occasions on what was believed to be larger driftwood type branches. As a result of the timber the cutterhead had to be reversed at times to advance the machine and several times the slurry flow also had to reversed to clear the cutterhead ports.

Once under the estuary, a higher silt content in the face was periodically encountered that slowed down the extraction of fines in the separation plant, which in turn resulted in a slowing of MTBM penetration rate.

Tunnel invert level varied from 8.4 m below existing ground level at CMA2 to 13.5 m at CMA3. The lowest point of cover was under the main channel of the estuary where cover was about 4.2 m. The water table was within 1 m of ground surface. During the first quarter of the drive, a number of sinkholes appeared above the tunnel line.

The maximum jacking force required on Drive 1 was 600 tonnes, which was after a 72 hour stoppage to reinforce a damaged launch seal. Typical jacking loads for most of the drive were 300 to 400 tonnes, with the jacking force increasing gradually with drive length, as would be expected.

Notwithstanding the variable conditions, the 874 m long drive successfully holed through into the CMA1 shaft approximately 15 weeks after starting, at an average rate of about 7.5 m per day.

Drive 2 construction

As a result of the sinkholes occurring in Drive 1, there was considerable concern by the council over the potential for sinkholes along Drive 2 in Jellicoe Street and the effect these may have on public and traffic safety, property and buried services, including the 150 mm existing sewer line above the pipeline. It was decided that additional site investigations were necessary to determine whether variable conditions as encountered in Drive 1 would be present and an emergency contingency plan was prepared.

The site investigations comprised additional cored holes, cone petrometre tests, sampling and grading. One hole near the start of the drive indicated relatively high silt content, but apart from that, the investigations showed a more uniform sand profile than encountered in Drive 1, with only minor traces of shells and timber.

McConnell Dowell chose not to use the D-Mode feature on the MTBM for Drive 1. While it was not clear whether this would have improved the face stability and prevented the sinkholes, the decision was taken to use D-Mode on Drive 2.

The 604 m long Drive 2 commenced on 11 October 2007 and was successfully completed after approximately 7 weeks, with an average rate of 12.5 m per day. Jacking loads increased from around 80 tonnes to 200 tonnes at completion, well within the 850 tonne capacity of the main jacking station.

Importantly, the drive was completed without sinkholes or any other incident and settlement monitoring was well within the design parameters.

Drive 3 construction

Drive 3 construction commenced from the dunes shaft at CMA3 on 3 January 2008, after the separation plant and other facilities were relocated from CMA2. The original drive length was to be 830 m, however as the marine trench dredging had commenced, McConnell Dowell made the decision to stop the drive at 808 m to ensure that the MTBM and the leading pipes remained in stable ground.

The drive was completed on 4 February 2008 after an average rate of 25 m per day, on two 12 hour shifts, seven days a week. The best day was 45 m. Ground conditions were excellent, with very little silty material being encountered and the penetration rates reflected this.

Average penetration rates increased from about 70 mm/min to a maximum rate of 120 mm/min at 700 m. The penetration rate then reduced and the jacking loads increased significantly.

The jacking loads increased to over 600 tonnes at about 700 m, prompting the activation of up to three of the intermediate jacking stations. A gelling agent was used in the bentonite to counter the flocculating effect of saltwater but the injection rate of the bentonite along the pipeline was not increased with the increasing penetration rate. The higher jacking loads were therefore attributed to reduced lubrication along the pipeline.

D-Mode was not used in Drive 3 because ground conditions were expected to be uniform, cover was high and there were no consequences of sinkholes or settlement.

Conclusions

Microtunnelling proved to be the most economical option for the Christchurch City Council Ocean Outfall project, as well as the option with the least environmental and community impact. The project was the first time microtunnelling has been used on this scale and over this length of drive in New Zealand.

Once into construction the microtunnel operation presented the contractor with a number of difficult challenges, including variable ground conditions, a drive beneath an estuary with minimum cover, noise effects on the community, managing risks along Jellicoe Street and the final drive beneath the surf zone to the wet recovery of the MTBM.

The three drives were all successfully completed without any significant incident.

The project has demonstrated that pipe jacking of drives of this length is well within the limits of current technology.

The ocean outfall project has also confirmed the many benefits of choosing the microtunnel option over conventional dig and lay construction as well as clearly demonstrating that in a situation such as this, it is a cost competitive solution.

This article is a summary of the paper by Ron Fleming, John Moore and Gwyn Jones entitled Microtunnelling the Ocean Outfall Pipeline, Christchurch, New Zealand. The paper was presented at the Australian Tunnelling Society conference in May this year.

Project Hobson: strength to strength

Oraki sewer replacement

Watercare is boring the tunnel to replace the 90 year old sewer pipe which currently bisects the bay on Auckland’s waterfront Tamaki Drive. No deep sewer tunnels of this size and complexity have been built in New Zealand.

The $NZ118.6 million Oraki Sewer Replacement, Hobson Bay Tunnel Project (Project Hobson) will see the replacement of the concrete sewer with a 3 km tunnel.

The new tunnel will meet projected growth in the area, practically eliminate wastewater overflows into the bay and the Waitemata Harbour, open the bay for recreational purposes and improve the views from Tamaki Drive.

Watercare Project Manager Mike Sheffield said that Project Hobson began with extensive consultation with the local community and regulatory bodies. Together with the approvals and design process, the planning was completed over a period of six years.

Implementing the GBR

Mr Sheffield told Trenchless Australasia that a Geotechnical Baseline Report (GBR) should comprise a realistic and quantative assessment of the geotechnical conditions to be encountered at a project site and forms an integral part of the conditions of contract, in particular the unforeseen conditions clause. The GBR provides both the employer and the contractor greater certainty as to the allocation of risk and also provides the employer with a better basis for obtaining and evaluating tender prices.

In tunnelling, in particular, many aspects associated with ground conditions will have a major influence on time and cost; the critical issues are cuttability, support, and all phases of spoil handling.

Extensive site investigation is therefore essential. Watercare invested approximately $NZ1 million on site investigation for Project Hobson undertaking some 60 boreholes, said Mr Sheffield.

Heavyweight TBM in NZ

The TBM machine was chosen for several reasons including the technical requirements of the job, environmental factors and because the machine was specifically designed for the ground conditions, geology and location of Hobson Bay.

Watercare said the TBM is a heavyweight in the construction world and its advanced capabilities are a New Zealand first.

The TBM was manufactured by Lovat. The machine is a mixed face earth pressure balance machine, weighing 270 tonnes and measuring 75 m in length. The diameter is 4.32 m.

Due to the immense size of the TBM, it was shipped from Canada in segments and was assembled 35 m below ground in a specially prepared shaft and a back shunt tunnel.

To enable continuous tunnelling, a temporary noise enclosure was constructed. Measuring 50 m long and 25 m wide, the enclosure was insulated with two layers of acoustic lining and clad with steel.

Mr Sheffield said this enabled tunnelling to take place round the clock by keeping the external noise below the levels permitted in the resource consents.

Tunnelling started in June using innovative technology that allows the machine to complete the work in one pass. The company said that the machine drills through the rock at the boring face, while at the tail end of the machine the tunnel is lined with pre-cast concrete segments. The gap between the segments and the rock is grouted, ready to go.

Once sealed and lined the internal diameter of the tunnel will measure 3.75 metres. Debris from the excavation is removed using a small train system.

The slab

The new pump station is an important component of Project Hobson. In April of this year a concrete pour required approximately 130 concrete trucks to deposit 700 m3

The concrete formed a 1.4 metre thick base slab for the new pump station on the Orakei Domain. Flygt Pumps from Sweden supplied six pumps for the pump station.

The large scale pour was necessary to ensure the pump station has enough weight to support the structure on top and to counteract the uplift from groundwater.

The station will pump waste water from some central and eastern suburbs to the Mangere Wastewater Treatment Plant for processing.

Obstacles overcome

Some of the challenges identified by Mr Sheffield included the construction of the pumping station. As the shaft is 38 m deep and 3 m in diameter this component of Project Hobson required careful thought in regards to the method of excavation.

Watercare also carefully selected a tunnelling method that would be able to handle the specific conditions of the project. Other techniques considered to replace the old pipeline included a new pipeline, alternate tunnelling options or a surface pipeline.

Project Hobson: the future

Works on Project Hobson began in May 2007. The new tunnel is due to be completed in 2010, following the removal of the old pipe.

HOBAS goes Global

HOBAS Pipe of Austria is the world’s only maker of GRP jacking pipe and Global Pipe is Australia’s exclusive agent for HOBAS pipe. Managing Director of Global Pipe Andrew Holman spoke with Trenchless Australasia about the advantages of using HOBAS jacking pipe in the installation of underground infrastructure.

Pipes for jacking are subject to very high loads during installation. The quality of the surface, the jointing system, as well as the physical property of the pipe is important for the successful use of pipe material. Following the installation, the pipes must meet the hard requirements of day-to-day operations – the pipes must be leak-free, corrosion-resistant, have a hydraulic smooth interior surface and be flush safe.

What are the advantages of HOBAS jacking pipe?

The HOBAS pipe consists of a thermosetting composite material. During the automated centrifugal casting process, several components of the compound material are fed into a rotating mould, degasified by rotation with a pressure of 30 to 50 bar, compacted, and tempered.

Mr Holman said that the pipe has many advantages. “Of particular interest are the lower machine costs and reduced excavation due to the smaller outside diameter that is a by-product of the thinner pipe walls.”

A smaller drill hole automatically means that less ground material has to be removed, transported and disposed. The result is considerable savings in excavation work that can amount to 14 to 53 per cent depending on the nominal diameter. The smaller drill hole will often translate into reduced boring costs.

The other major benefit is the inherent flexibility in GRP Mr Holman said “The pipe is able to compensate for minor irregularities in the face of the machinery or bore by means of elastic deformation. This elasticity also means that no wooden spacer rings are needed in the joint.

“The use of wooden spacer rings should be considered the weak link in any jacking project as the wood is left behind and will swell in the joint and deteriorate faster than the rest of the pipe system.”

The HOBAS jacking pipe will work well in any pipe jacking or boring project. Mr Holman said that the pipe is particularly cost effective in projects where the jacking/boring is happening in rock. If there is a high boring cost due to the geology, then there is typically a major savings by having a HOBAS pipe that meets the criteria of the internal pipe diameter but has a substantially smaller external diameter due to its thinner pipe wall, Mr Holman explained.

Stage two of the Epping Branch sewer in Victoria will use DN1000 GRP. The project will begin in April-May 2009. The Epping sewer combines 1,143 metres of open trench and 877 metres boring using HOBAS jacking pipe. The ground condition for the bore is mostly solid basalt. The contractor on the project is MFJ Construction.

Anthony Caligiuri from Califam Construction, a customer of Global Pipe, said he was very pleased to see HOBAS jacking pipe available in Australia. Mr Caligiuri said it is his preferred pipe choice. “The advantage is the thinner wall, which significantly reduces boring costs.” Mr Caligiuri has a number of jobs earmarked for the GRP pipe.

The pipe is available Australia-wide in diameters from DN200 up to DN2100.

Danish mobile dewatering saves time, fuel and money

Transport, handling and disposal of sludge are environmental challenges and represent significant costs for municipalities, waste management companies and related industries. The MaskoFlexå¨ unit is a mobile dewatering unit, developed and manufactured in Denmark.

This dewatering technology holds advantages for the recipient, the contractor and the environment. The MaskoFlex may be considered as a mobile treatment plant as the dewatering process is carried out on site and the reject water is immediately returned to the source. The bacterial culture is thus kept intact at the source, which ensures an optimum function septic tank system or a grease trap.

The dewatering system removes water from the sludge by means of polymer, reducing the amount of sludge significantly. Septic sludge is reduced by more than 80 per cent and the system has a proven high efficiency on bio-waste, and grease as well. Customer Donal Kearney of AQS Environmental Solutions Ltd, Ireland said “The JHL dewatering technology ensures continuity throughout the workday and therefore saves time, fuel and money.”

For Salters Cartage in New Zealand, the MaskoFlex has also made a significant difference, “Seeing 25,000 litres of septics go in and 1,000 litres of solids come out enforces our dedication to buy from J. Hvidtved Larsen A/S”, said Ron Salter whose fleet counts several different JHL units.

The dewatered sludge is highly suitable for further treatment and thus easy to handle at disposal sites and treatment plants. In all, the environmental benefits of the MaskoFlex are obvious, as the reduced amount of sludge requires less transport, minimising the CO2 emission, and imposes less or no strain on wastewater treatment plants and disposal sites.

Delivering desalinated water to Sydney

The new pipeline and its associated infrastructure and systems will carry the desalinated water from Kurnell, across Botany Bay, to the city’s main water supply, the City Water Tunnel at Erskineville.

Three tunnel boring machines (TBM) will be employed to minimise the disturbance to residents and also to protect unique tracts of seagrass along the Botany Bay floor.

TBM: managing the environment

The southern shore of Botany Bay contains extensive seagrass beds, which are a valued and protected part of the estuarine environment. Three species of seagrass are present off Silver Beach at Kurnell: zostera capricorni or eelgrass; posidonia australis or strapweed; and halophila ovalis or paddleweed. Posidonia requires the greatest consideration due to its slow reproduction and poor propagation by seed.

Stretching about 6,500 metres in a westerly arc from Silver Beach at Kurnell to Lady Robinson’s Beach at Kyeemagh, the twin and single steel pipelines will impact approximately one per cent of the overall area of Botany Bay. Along the whole route, however, less than half of one per cent of existing seagrass along the southern shore (0.45 per cent) and Botany Bay (0.42 per cent) will be removed as a result of pipeline construction.

Trenching through these seagrass beds would have required a seagrass management plan to be implemented during and after construction, and a compensatory seagrass package involving steps like transplantation. Instead, Sydney Water has chosen to microtunnel the pipeline from its Silver Beach construction area under Botany Bay for a distance of about 800 metres in order to protect the seagrass.

The Water Delivery Alliance will join the single 1,800 mm diameter pipeline from Silver Beach to the twin 1,400 mm diameter pipeline about 800 metres from the shoreline, and (as always) protection of the environment will be a key consideration. Pit construction is nearing completion at the Silver Beach site. This pit is supported by secant piling, has internal jet grouting and is around 10 metres deep. Land-based sections of the pipeline will be constructed first. Material that has been dug up from the pit is being used on site, where possible, in order to minimise truck movements. Continual water quality monitoring is carried out around the Silver Beach construction area. Recent monitoring of the site has indicated good water quality conditions, with similar results both inside and outside the silt curtain.

TBM onshore

A TBM is also an essential tool to minimise disruption onshore. The bore passes beneath Tasman and Dampier Streets, Kurnell for the water delivery pipeline. The model shown is a Herrenknecht earth pressure balance and AVN machine, weighing approximately 100 tonnes.

The first microtunnelling drive through a residential area is now complete. The TBM tunnelled 640 metres from the launch pit in Cook Park, under General Holmes Drive and under Tancred Avenue to the receival pit at Muddy Creek. The TBM used was chosen specifically for the conditions at Cook Park. The pipe liner and services will be installed on this section of pipe in the coming months.

The TBM has also finished tunnelling 645 metres from Canal Road to Botany Freight Rail Line, which was the first tunnel complete on the project. Microtunnelling from Marsh Street in Arncliffe, under the Cooks River to Tempe Recreation Reserve is set to begin in March.

Choosing the route

The pipeline route across Botany Bay was chosen because it avoids known areas of contamination. Every practical effort is being made to protect the Bay environment during construction. Water quality monitoring is ongoing during construction activities, in accordance with the Construction Water Quality Management Plan. The results of this monitoring will help the project team manage their work.

Project scope

The main project works are:

  • A drinking water pumping station on the site of the desalination plant in Kurnell.
  • Infrastructure from the pumping station to the existing water supply system in Erskineville, via Silver Beach and Kyeemagh, including associated connections and flow and pressure controls.
  • Marine works consisting of twin 7.5 km long, 1,400 mm diameter steel pipelines across Botany Bay;
  • Approximately 6.4 km of 1,800 mm diameter mild steel cement-lined onshore pipe, slipped inside 2,100 mm diameter concrete pipes and installed by trenchless microtunnelling; and
  • Approximately 3 km of 1,800 mm diameter MSCL onshore pipeline, installed by dig and lay conventional trenching methods, with sheetpile and trench box shoring as required.

Overcoming challenges

Given the size of the project, and the locations it must traverse, considerable pre-planning and consultation has taken place with various regulatory authorities and the many wider stakeholders, including the community that will be affected by construction operations along the pipeline route. The Water Delivery Alliance has in place a structured team of proven community and environmental personnel, providing support to the wider team and ensuring that all approvals have been obtained and that stakeholders are well informed of both the program and methods of the activities that will take place in their vicinity. Community feedback has been encouraged and adjustments to the method or timing of activities have been made to accommodate the community’s concerns, wherever possible.

This project is breaking new ground to achieve the distances set for the tunnel drives, while the sizing of the laybarge operations require laying twin 1,400 mm diameter pipe in a pre-dredged trench across the vast Botany Bay waters, which is likely to be challenging. Some of the tunnels will be the longest undertaken by pipe jack method in Australia, and potentially within the Southern Hemisphere. No twin pipeline of this diameter, laid simultaneously from a barge for 8 km, has been executed previously in Australia.

Notwithstanding the considerable challenges that exist, the Water Delivery Alliance team are well skilled and committed to overcoming them, utilising innovation and a team culture that is striving for the completion of this project on time, in a safe manner and surmounting technical challenges to break new ground.

Glenelg to Adelaide: pipeline shoots ahead

The Glenelg to Adelaide Parklands Reuse Scheme is a $A74.5 million project providing extra treatment facilities, a 10 kilometre pipeline from Glenelg to Adelaide’s CBD, and approximately 30 kilometres of pipeline around the Parklands. It will enable about 3.8 billion litres of treated water to be recycled annually.

In addition to supplying existing customers, the project will provide a minimum of 1.3 billion litres each year to irrigate the Adelaide Park Lands. This landmark project will provide a sustainable long term solution for watering the Park Lands and can provide opportunities for the development of additional recycled water initiatives.

This project is being delivered by the CityGreen Alliance, which includes SA Water, United Water, Leed Engineering and Construction, Leighton Services, and Guidera O’Connor.

Trenchless takes off

Shoota Trenchless Drilling is responsible for the thrust boring and pipe jacking of GRP for the CityGreen Alliance. The project began in October 2008 and will be completed in April 2009.

The trenchless aspect of the project comprised five thrust bores (auger bores). Shoota operated two McLaughlin borers; one with a diameter of up to 900 mm and the other capable of a
1,350 mm diameter. On average, each bore took approximately seven days to complete, taking into consideration delays for wood, running sand and other obstacles encountered by the team.

Launch pit

The launch pit was dug by Shoota’s 22 tonne excavator. Each shaft was approximately 10.5 metres long and 2.5 metres wide and varied in depth from 2 – 5 metres. Some shafts were benched out metre by metre. However, if the company could not bench out, a shoring box was put in the shaft. Each shaft took approximately half a day to prepare for drilling.

Ground conditions

The ground conditions have varied from running sand at Taply Hills Road to clay. At Taply Hills Road, the running sand meant that bore had to be spare point.

Bores

The Anzac Highway road crossing was 18 metres in length. An old water main was struck, which had to be cut out of the way. The company also completed two 42 metre bores and a 72 metre bore on Peacock Road in Adelaide City, which saw 30 metres drilled in the first day.

The Taply Hills Road crossing, a main highway, was a 56 metre bore near the Adelaide Airport. The bore was completed at night, over durations of six hours per night. This bore was quite challenging as the airplanes disrupted work. The airplanes were combined with a number of other obstacles, such as old wooden sleepers that were drilled into. Due to the nature of the work, the Taply Hills Road bore was completed in two weeks.

Pipe jacking

Shoota also used a pipe jacking station with a Volvo power pack. The team pipe jacked one shot of 80 metres of steel casing.

Challenges

There were a number of challenges to overcome in the successful completion of the trenchless aspects of the Glenelg to Adelaide pipeline. Shoota Trenchless Drilling General Manager Steve Schut said that the limestone clay caused a lot of friction on the pipe. “In regards to the proximity of the airport, airport safety officers were present at night in order to communicate with the traffic tower so we knew when the boom of the excavator had to be lowered for incoming and out going planes.” Mr Schut said the continuous downtime with the planes taking off and landing was understandable. Shoota had limited hours of work with only a six-hour window at the airport, combined with the disruptions of the planes. Mr Schut said “The airport personnel were very co-operative with us.”

Shoota worked with the drilling department of Leed Engineering and Constructions to complete the works. Shoota has previously completed drilling projects such as the Bendigo recycled water pipeline, Gippsland Water Project, the Goldfields Superpipe and the Casterton-Coleraine pipeline.

Current construction report

Construction of the new recycled water treatment facility at the Glenelg Wastewater Treatment Plant is now underway. The first stage of the underground pipeline in Adelaide Airport Limited land has been completed, and installation of the trunk main pipeline in the suburbs of Netley and Marleston is ongoing. A CityGreen Alliance construction team is currently installing the ring main pipeline in the eastern and southern Park Lands, and a second team is working in the northern Park Lands, within the North Adelaide Golf Course.

The underground pipeline is being constructed at a number of locations concurrently in West Torrens and the Park Lands to ensure timely construction completion. Completion of the project, with water in the Park Lands for irrigation, is planned for mid-2010.

Australia’s water future

The South Australian Minister for Water Security Karlene Maywald said “Water is one of our most precious resources and it needs to be carefully managed to meet the needs of all South Australians – now and in the future.

“On completion, the project will deliver a sustainable supply of recycled water for the Adelaide Park Lands and Adelaide City. The project will provide ecological, social and economic benefits for government, business and the community.”

Behaviour of segmental lined tunnel on overburden removal

Case Study: Putra LRT Tunnel

The project owner is KL City Council (Dewan Bandaraya, Kuala Lumpur) and the LRT tunnel asset owner is Syarikat Prasarana National Berhad (SPNB). The project concerned the construction of a dual carriage underpass above a LRT tunnel. The clearance between the road underpass to the LRT tunnel crown is approximately 1.9 metres after considering the depth of the base slabs of the structure.

The main restrictions imposed on the underpass works in relation to safeguarding the LRT tunnel included a limited tolerable displacement of the tunnel from vibration impacts during installation works e.g. installation of the king post, sheetpiles, grouting etc. Other restrictions included the limited tolerable displacement associated with the removal of overburden and the minimal imposed loading on the tunnel due to the underpass, either during construction or in its permanent state.

The geology of the site consisted mainly of rock mass of meta sedimentary rock formation of interbedded sandstones and shale of Upper Silurian-Devonian age (Kenny Hill formation) overlaid by alluvial deposits. The water table fluctuated between 6 to 8 metres of depth from the surface depending on the season.

The road underpass construction

The methodology for the road underpass construction consisted of permanent sheet piling system and king post coupled with steel strutting and temporary removable ground anchors and top down excavation. Refer to figures 1 to 5.

Tunnel instrumentation

A detailed study was carried out on the instrumentations required to ensure adequate monitoring and response times. The objective was to install an instrumentation system that was able to measure movements of the tunnel and to provide warning on excessive displacements.

Several constraints were identified;

  • Access to the tunnels for manual readings was limited to four hours per day (i.e. during non-operational hours of the trains);
  • Train operations introduce dynamic forces onto the installations within the tunnel;
  • Construction works on the underpass had to be carried out during the day, hence the need to obtain information immediately rather than in non-operational hours.

Based on the above considerations, real time monitoring systems were chosen. These systems were backed up by the following manual systems;

  • The automatic and real time displacement measurement using electro level beams (ELB) was used to find a measurement of displacement measurement at the tunnel crown level. The ELB system consists of a horizontal electrolytic level sensor with measurement range of 40 arc minutes and resolution of 1 arc second (0.01 mm for a 2 metre beam). The beams were two metres long aluminium and had a large temperature operating range of -20 to 50 degrees Celsius.
  • The automatic and real time displacement measurement basset convergence system (BSC) was installed to measure the tunnel ring deformation within 20 metres of the centre zone of the monitoring zone. These readings provide direction of movements in 2D. They were installed at five ring intervals (5 metres). The BCS systems consist of double electrolytic tilt sensors to an accuracy of 0.02 mm and measure along two axes (vertical and horizontal). Low profile design enables the system to fit close to the tunnel wall. The brackets and steel arms were stainless steel.
  • The purpose of thee electro-optical survey systems (ATMS) instrument was to serve as backup and checking system for the real time electrical sensors of the ELB and BCS systems. The ATMS consists of an automatic target recognition (ATR) system, which is fast and accurate in referring to a fixed datum. It is essentially an automatic total station with 0.5 inch angle measurement accuracy (0.05 mm), mini glass reflective prisms, APS Win data acquisition software and data analysis and report generation software.
  • The purpose of the Manual Level Survey Markers was to derive the absolute movement of the track slab. The system consists of survey markers at two metre intervals along the track slab with a survey accuracy of 0.01 mm.


Tunnel displacement

In stage one of the works, excavation to five metres, the tunnels settled or shape deformed, to about 3 mm at the crown during the installation of the king posts, preparation of the steel decking, and minor excavation works to -1 metres. The settlement at track level was less than 1 mm. It was noted that this was due to the additional surcharge introduced by heavy excavation machinery at the surface.

On completion of these works, the excavation to the 5 metre level commenced and the tunnel began to heave with further shape deformation, however the rate of displacements was within the predicted rate and the absolute displacements was within the predictions at crown and track. As the overburden was reduced, the surrounding ground relaxed and the stresses within the tunnel linings begin to redistribute due to the loading relaxation, and the tunnels began to deform under the new stresses.

Jet grouting

The tunnels continued to heave during the jet grouting works. It was concluded that this was the short and medium term results of the ground relaxation effects. The rate of heave slowed down as expected and within the predicted displacement estimates. There was no reduction of overburden during this stage.

The grout cap improved the strength of the soil surrounding the tunnels. The triple phase jet grouting technique was selected. The grout forms a body of cemented soil above and alongside to maintain the shape profile of the ground in order to minimise ground relaxation surrounding the tunnels. Dewatering wells were installed during this stage. This had the effect of reducing the flotation pressure during the temporary works.

On completion of the grout cap, underpass excavation resumed to a depth of 7 metres. The rate of heave was much lower than the stage one rate, which again corresponded to the predicted rate at tunnel crown location, but was higher at the track level. The lower heave rate was due to the counteraction between the inverted U shaped jet grout cap and the settlements, resulting from the drop in the water table by the dewatering works.

The track level, absolute heave value was 60 per cent higher than predicted. This was assessed carefully and it was concluded that further mitigation works were needed. The excavation sequence was changed to reduce the amount of excavation by zoning and limiting the excavation works and introduction of permanent loadings within these zones.

In stage three of the project, excavation from -7 to -9 metres, the tunnel heave continued and the rate of the displacement at crown was slightly above the predicted value. This was at a crucial time since the excavation depth was just above the crown level. The frequency of the data gathering was increased and assessments were conducted on a daily basis.

The measured heave at the crown level was 10 per cent (11.8 mm) above the predicted value and the measured value at the track was 138 per cent (6.2 mm) above the predicted value. However, based on the design assessments, the out of balance radial stress was within acceptable limits. To mitigate the risk it was recommended that base slab construction of the underpass should be expedited. The tunnels were monitored continuously during this stage with the real time reading intervals set at one minute.

Conclusions

The following graphs illustrate the monitoring data over the project period at various stages of the works. They provide a comparison between the predicted displacement based on finite element analysis, as well as actual displacement at both the crown and invert levels of the tunnel against various stages of the excavations. It is observed that theoretical predicted displacements from the analytical work and actual monitored displacement showed trends in correspondence with variations to the absolute values at track level.

The deviation was a cause of concern and back analysis was carried out with additional adverse soil parameters in order to predict the revised displacements. The results indicated that the absolute maximum of 15 mm would not be breached. Probable cause for the differences was soil profile variation within short intervals, as was observed during the tunnel drives.

The real time monitoring provided the necessary information for immediate response to an event and the manual monitoring provided essential back-up checks. It is noted however that the absolute values comparison between the real time and prism monitoring at the crown level showed a lower absolute displacement value for the real time monitoring than the prisms.

Post completion monitoring continued over a period of six months until negligible displacement. Pre- and post dilapidation surveys of the affected length of tunnel were carried out and no structural deterioration of the tunnels was observed.

Pipe jacking record in Perth

The pipe jacking operation was part of a suite of works by the Alkimos Water Alliance to install new wastewater services in Perth’s northern suburbs. The Alliance consists of the Water Corporation, Brookfield Multiplex, Macmahon Contractors and Zublin.

Alliance participant Zublin was responsible for the pipe jacking operation, which involved laying the 2,000 mm internal diameter plastic-lined concrete reinforced sewer pipes.

Alkimos Water Alliance representative and Tunnelling Package Manager Josef Kofler said on 24 November 2008 that his team had successfully installed 84 metres of pipe within a 24-hour period using a “÷dual mode’ tunnel boring machine.

“This was an Australia-wide pipe jacking record,” Mr Kofler said.

Pipe jacking in Perth

Construction of the pipe jacking works began on 16 February 2008 and was completed in early March 2009, three months ahead of schedule.

Pipe jacking will start again in April 2009 in a separate area and will involve making three tunnels of a total approximate length of 1,500 metres. This work is in addition to the original work package awarded in 2008.

The original works included the construction of ten temporary jacking and/or receiving shafts along the sewer alignment at varying depths between 8 and 20 metres. At each temporary shaft location, a permanent access chamber was installed for future access for inspections and maintenance. Depending on topography, construction and operational constraints, distances between the shafts varied from between 270 metres and 606 metres. The temporary shaft construction in the sandy strata was undertaken using concrete caisson segments with an internal diameter of 8.8 metres. Where the limestone formation was encountered, the walls of the temporary shafts were lined with reinforcing mesh and shotcrete.

Zublin also designed and manufactured the 3,000 mm long jacking pipes used in the sewer. The vertically wet-cast pipes have an internal diameter of 2,000 mm, a wall thickness of 225 mm and are designed for jacking forces of 8,100 kN. Corrosion protection was provided for the pipes by the addition of a 2.5 mm thick, 360 degree HDPE liner, which was cast into the concrete pipes. A stainless steel collar at each pipe acts as a guide during installation and together with a rubber seal seated on a recess, creates a watertight seal at each pipe joint.

Ground conditions

In general, the geology of the Perth metropolitan region consists of sandy overburden, derived from the underlying layer of limestone bedrock of the Tamala Limestone. Ground conditions along the 5 kilometres of sewer were highly variable, ranging from full face medium dense sand to a full face high strength calcarenite/siliceous calcarenite. In the sandy strata, limestone pinnacles of varying strength and diameter, typical of the Tamala Limestone formation, were encountered by the tunnel boring machine. However, this did not provide any problems for the operation. The rock strength was also highly variable and ranged between 1 MPa to 80 MPa. Dry fine sand was also found to overlay the limestone formation.

Alkimos Wastewater Treatment Plant

The Alkimos Wastewater Treatment Plant will provide a much needed service to Perth’s expanding northwestern corridor and will ultimately serve approximately 750,000 people. The plant will be owned and operated by the Water Corporation of Western Australia and will be built in a staged approach, with an ultimate capacity of 160 megalitres (ML) per day.

The contract to design, construct and commission the first stage of the plant has been awarded to the Multiplex MacMahon Zublin Joint Venture. This first stage will accommodate 20 ML per day, with the second stage required in 20 years.

The first stage will include a series of permanent and temporary structures to be decommissioned progressively during the second and third stages of construction. Works will include a permanent flow reception chamber, temporary screening facilities and a potable water system comprising bores, storage tanks, disinfection and a booster pump station. The plant will have a permanent incoming HV switch room, module one switch room and associated roads, drainage, connecting pipe work, landscaping, security and fire system.

Construction of the plant is scheduled to start in April 2009, with the plant to become operational towards the end of 2010.

SRWP tunnels provide water windfalls

The State Government regional infrastructure project will enable water to be shared among five local council areas – Brisbane, Gold coast, Ipswich, Logan and Scenic Rim councils – moving water from areas of surplus to where it is needed most.

These councils have enjoyed the prosperity of booming populations, a trend that has been accelerating over the last few years. At the same time, they have struggled to manage allocations of an ever-diminishing drought-affected water supply. However, from the start of next year this struggle will ease with the ability of the pipeline owner, the Queensland Bulk Water Transport Authority (trading as LinkWater), to transfer water over an area covering more than 7,500 sq km.

The Southern Regional Water Pipeline Alliance (SRWPA) Program Director Paul Tracey said the project broke new ground with its microtunnelling, tunnel boring and pigging techniques.

“The tunnelling crews have done an outstanding job building ten microtunnels in challenging conditions within very tight time frames, including crossing four rivers and twice crossing the Pacific Highway,” said Mr Tracey.

Ground conditions associated with sinking shafts for river crossings required substantial temporary works to support soft, wet alluvial ground conditions on steep river banks and to create a cut-off against the ingress of river water.

Microtunnelling

The SRWP project completed ten microtunnels in only 18 months. The tunnels have a combined distance of more than 2.2 km and depths of up to 30 m. These tunnels cross four rivers, four roads, a major motorway, including the on and off ramps and the main rail line between Brisbane and the Gold Coast.

As the project was operating on a fast track schedule, tunnelling involved 12 hour shifts that operated 24 hours a day, six days a week, with staff rotating shifts for 12 months.

Some sites were limited in size due to their proximity to suburbs. This meant the crews could not stockpile pipes and had to organise daily deliveries. These smaller sites also determined the positioning of cranes. Instead of having mobile cranes move around the site, the crew secured one crane in an optimal location to operate as needed. They further reduced project risk by implementing physical and mechanical lookouts, as well as proxy volts that sense overhead power lines and automatically shut down the crane whenever the boom comes within a predetermined distance of the hazard.

Tunnel boring

Two Herrenknecht AVN 1500TB microtunnelling machines were put to use 24 hours a day for 14 months, reverting to 12 hour shifts in built up areas.

Both tunnel boring machines (TBMs) operated using a slurry system and were predominately set up for hard rock and mixed ground conditions. The TBM cutters and the slurry system faced high wear risk due to the abrasive nature of the rock. For this reason, a cutter overhaul workshop was set up to rebuild cutters and maximise the potential reuse of parts. A substantial consignment of spare parts for the tunnelling equipment and solids separation equipment was stored onsite to ensure the workshop could immediately respond to maintenance needs.

Mr Tracey said the project saved hundreds of thousands of dollars by recruiting staff to operate the machines, as opposed to hiring subcontractors.

“By doing the more difficult jobs in-house, SRWP built staff capability, ensured the project remained accountable for operating the equipment and better managed potential issues.”

In total, the project conducted 320 vertical metres of jacking and bored 2,382m of tunnel. This included 25 auger bore road and rail crossings of lengths from 30m to 125 m, with a total installed length 1,346 m.

Hyperbaric tunnelling

To manage the hyperbaric conditions involved in microtunnelling, the SRWP project partnered with the Wesley Centre for Hyperbaric Medicine (WCHM) to conduct comprehensive risk assessment.

This assessment helped ensure crew safety by developing procedures, formally certifying machinery and coordinating medical requirements.

The TBMs were certified by the WCHM to ensure the machines complied with work place health and safety regulations and a decompression chamber and hyperbaric medical support were provided on a 24/7 basis during the tunnelling operation.

The SRWPA also co-ordinated all life support systems and support personnel, organised “÷dive’ medical assessments for the caisson workers, lock operators, paramedic and intensive care nursing staff and established and practised an emergency evacuation exercise with SRWP staff.

Pigging

The first challenge for the crew was incorporating the pigging runs into a tight schedule of SRWP works

Mr Tracey said that there are no applicable standards that relate to pigging, only proven operating methods and procedures taken from lessons learnt in the past.

“So you do feel a bit as if you’re working without a benchmark, which can be both daunting and liberating,” said Mr Tracey.

Prior to the works, extensive pigging trials were completed to select the pig type and size used to ensure there was no damage to the bituminous coating to the cement lining inside the mild steel pipe. A pig’s diameter is traditionally designed to be larger than the pipeline. The SRWP crew tailored the pigs to reduce the oversize and avoid “÷snags’ while still being able to pig efficiently. The pigging crew was able to condense the program to gain schedule efficiencies.

Additionally, as a result of the relatively clean pipeline installation, the pig was able to be used without an initial high velocity flush behind the pig, practically halving the time normally taken to do this task. Water flow was controlled by using the pipeline’s temporary valves to manage water pressure in the pipes.

The pigging crew completed their activities as scheduled. The longest pigging run measured 16 km, taking around nine hours and 15.5 megalitres of water to complete.

After pigging, the pipelines will undergo testing and commissioning. All SRWPA projects will have finished commissioning by 31 December 2008.

Tunnelling Melbourne’s future

The NSP is being jointly delivered by Melbourne Water (Stage One) and Yarra Valley Water (Stage Two). The John Holland Group has been awarded the contract to construct both stages of the NSP. The NSP will help protect the Merri and Moonee Ponds Creeks from the damaging impact of sewage overflows that can occur after heavy rain as well as provide for additional capacity to the Northern suburbs.

The project involves the construction of approximately 13 kilometres of new sewer pipes ranging in diameter from 1.6 to 2.5 metres. The sewers are generally located along the Merri Creek Valley and Moonee Ponds Creek, from Reservoir to Essendon. Eight major access shafts of up to 65 metres in depth and 13 metres in diameter will also be constructed across stages one and two.

The NSP is one of a number of future projects to be delivered under a collaborative arrangement between John Holland, Melbourne Water and Yarra Valley Water. Project Managers Connell Wagner and design partners SKM-Jacobs are working with John Holland to deliver this project.

Site selection

Community Relations Manager for the NSP Trent Woodberry said that a thorough site selection and extensive consultation process was undertaken by Melbourne Water and Yarra Valley Water to determine the route of the sewer and the worksites, prior to construction. This process involved local councils, community groups, Vic Roads, Environmental Protection Agency Victoria, Local Councils, State Government departments and local Members of Parliament.

Working with the community

Mr Woodberry explained that one of the biggest challenges is running 24 hour operations in an urban environment. “Many of our project sites are located in densely populated areas, meaning that community engagement is of the utmost importance.”

Seeking to minimise the potential impacts on the community was a major factor in the planning and design of the project and continues throughout the construction phase. Community forums are held on a regular basis to provide opportunities for residents and businesses near the shaft sites to receive updates on the project, and raise any questions or areas of concern. Community members attending these sessions have provided useful feedback on ways in which the project can minimise possible impacts.

The NSP team have also involved local schools as a key partner to the project by offering them an opportunity to name the three Tunnel Boring Machines (TBMs) to be used for construction. Local Primary School students in grades 1 to 3 were invited to colour in and name the TBMs. The chosen names were TBM 1 – Victoria, TBM 2 – Gemma and TBM 3 – Julia.

Managing the environment

During the project’s planning phase a number of detailed investigations were completed including an environmental assessment, which incorporates a biodiversity study, and archaeological and heritage studies. These studies provided the basis for the development of an Environmental Management Plan which guides how construction work will be undertaken to minimise the potential for environmental impacts.

Numerous geotechnical investigation studies were undertaken prior to the commencement of tunnelling activities, in order to ascertain what sort of geotechnical conditions were likely to be encountered during underground construction. The project is tunnelling at depths of between 19 – 65 metres across both stages, through variable geology including basalt, alluvium and Silurian sedimentary formations. At various points the project will be required to tunnel through basalt up to 270 MPa and also water bearing alluvial’s.

Constructing the tunnels

Three state-of-the-art TBMs have been specially designed and commissioned for use on the NSP: two Herrenknecht Earth Pressure Balance (EPB) TBMs and one Robbins Hard Rock TBM.

These TBMs are highly advanced and designed to operate in specific geological conditions. The Herrenknecht TBMs are designed to operate in mixed ground conditions, while the Robbins TBM will be used to excavate through hard rock, such as the basalt conditions expected on Stage Two.

Stage One – Melbourne Water

John Holland began construction on Stage One of the NSP in August 2007. Stage One involves 8 kilometres of sewer tunnel connecting to the existing sewerage system near Merri Creek at Coburg and the Moonee Ponds Creek at Pascoe Vale. The crews will use the two Herrenknecht EPB TBMs to complete Stage One.

Shaft excavation is underway or has been completed at three of the five NSP Stage One sites. Tunnel construction on the 1.6 kilometre tunnel length from De Chene Reserve, to connect to the Carr Street shaft is well underway. This tunnel is being excavated using an EPB TBM “÷Victoria’, which is the first to be used on the project. “÷Victoria’ is anticipated to reach the shaft site in Carr Street towards the end of 2008.

To facilitate 24 hour tunnelling operations three sophisticated acoustic enclosures have been constructed over the three main shafts. The bored piling works at the Bass Street and Vanberg Road sites have also been completed, ahead of schedule.

Stage Two – Yarra Valley Water

Stage Two of the NSP is a 4.6 kilometre long, deep-tunnelled sewer running from Carr Street in Coburg to L.E. Cotchin Reserve in Reservoir. It will connect to the Stage One works at Carr Street and will have a finished diameter of 1.8 metres.

In September 2007, John Holland signed a contract with Robbins for a 3 metre double shield TBM, with back-up, spare parts and cutters. The Robbins TBM will be launched from a 31.5 metre deep shaft at the Newlands Road job site.

Four access shafts of up to 39 metres in depth and 10 metres in diameter will also be constructed, enabling two specially designed TBMs – Julia and Victoria – to be utilised during construction. Drill and blast techniques are being used to excavate some of the tunnels, launch chambers and shafts.

Completion of the project is timed for mid 2012.

Harker underground in Timaru

In April, the team began work on the Timaru District Council’s $A14 million main trunk sewer upgrade. The project consists of three drives, all approximately 400 m in length. They are spread from the Washdyke Lagoon to Caroline Bay. The Harker team is scheduled to complete the job by the end of July 2009.

The team started from the lagoon end and headed south, using drill and blast for the first 150 m. The team then split and half headed north with an EX50 to eventually meet in the middle. Harker has also completed 106 m of open cut at the start of the most southern drive. This will be laid in 2.5 m OD concrete pipe and used for access into the ringbeam and lagging tunnel.

Project Manager Mr Bishop says that they are working 24 hours a day on the tunnel boring machine and day shifts on the conventional section. “The tunnel face is a split of clay and fractured basalt. Although the rock proved difficult to blast due to the clay seams, we have been averaging about 1.5 m per shift.

“The open cut had to be extended as we encountered some unexpected boulders in fill material; otherwise it’s been as the geotechnical reports predicted. We are enjoying the challenges of the job, which is both drill and blast with sections of ringbeam and lagging.” Harker now has 20 men onsite.

The company also has a $NZ10 million project underway for Auckland City – a storm water system upgrade – as well as a $NZ7 million sewer pipeline upgrade for North Shore City.

Trenchless Australasia 2009: fantastic speakers, footy, food and fashion

Trenchless Australasia 2009, the 8th National ASTT Conference and Exhibition will take place at Melbourne Park from 20-22 September, 2009. Delegates are guaranteed to take plenty away from the conference program, featuring a range of speakers covering projects, technology, the latest developments, policy and more.

With the confirmation of the keynote speakers for Trenchless Australasia 2009, the high quality of the technical program is guaranteed. Read on for an introduction to your keynote speakers.

The event has attracted sponsorship from the leading movers and shakers in the trenchless industry.

Platinum sponsor Interflow will hold 36 square metres of exhibition space and will sponsor the Gala Dinner. Gold Sponsor Vermeer is hosting the River Cruise. Parsons Brinckerhoff is a bronze sponsor and will provide Melbourne’s famous coffee. Other sponsors include Digital Control Incorporated and Westnet.

Old problems new solutions

Trenchless Australasia 2009 is honoured to have Dr Dec Downey, ISTT Chairman, as a keynote speaker. Dr Downey will share his considerable knowledge and expertise on the topic “÷The contribution of Trenchless Technology 21st Century pipeline construction and rehabilitation’. Dr Downey is back by popular demand following the very successful ASTT Roadshow.

“We often speak about the challenges of ageing underground infrastructure and the benefits of our technologies in addressing urban renewal with a minimum of disruption, but there is much more to say about the contribution of Trenchless Technology to the maintenance of existing networks and the construction of pipelines for the future,” said Dr Downey.

“Many of today’s problems can be attributed as much to the historic choices of materials and methodology available at the time of construction as to time-related deterioration and shortcomings in construction supervision. With the clarity of hindsight we can identify some of our past mistakes and build on this hard-earned understanding to do better for our communities and the trenchless option has so much to offer in these initiatives.

“Trenchless methods facilitate construction with less joints or better made joints, with potentially more durable materials and with less reliance on hard-to-supervise skills in the darker corners of the underground. Today we have improved geotechnical exploration and utility location skills, though further development is required. The practices of microtunnelling, pipe ramming and HDD have improved substantially. Modern pipe materials properly installed by these methods must surely offer sustainable solutions to the challenge.

“We have an increasing tool box of technologies to address ageing pipelines and provide lasting solutions to these problems. While condition assessment and service connection reinstatement remain challenging many of the rehabilitation techniques we use have been tried and tested over a considerable length of time and our retrospective evaluations can underpin service life predictions. New techniques continue to evolve along with our understanding of the pipe-soil interface. We have high hopes for emerging structural spray and reinforced linings.”

Dr Downey has worked in the pipeline business for more than 35 years, initially involved in the development of jacking pipe and confined trench construction methods he contributed to the Institution of Civil Engineer’s Conference “÷Restoration of Sewerage Systems’, participated in the first No Dig Conference “÷Trenchless Construction for Utilities’ in 1985 and was amongst the first members of the ISTT. He has served as UKSTT Chairman 1999-2001, ISTT Vice Chairman 2005-2007 and is the current ISTT Chairman. Dr Downey serves as a member of the Pipeline Industries Guild Utilities Panel and is a member of the CIWEM Editorial Board.

Dr Downey is a Principal at Jason Consultants Group, where he specialises in projects concerned with all aspects of pipeline rehabilitation including research and development, licensing and technology transfer, liner manufacturing and installation.

Dr Downey has worked for Insituform Technologies Inc. (ITI) in the field of CIPP since 1987 and as a consultant with the Jason Group on a wider range of renovation and pipe replacement methods since 2003. His development team at ITI pioneered pull-in and inflate methods, light curing, controlled head inversion pressure equipment, pressure pipe lining materials and methods and procedures for large diameter installations. He has had substantial involvement in the establishment of test methods, specifications and standards for CIPP. Educated at The University of Bath in the United Kingdom, Dr Downey has travelled extensively, working in Europe, North America and particularly Asia. He brings a global perspective on experience with CIPP and other rehabilitation systems.

Recent training courses on CIPP and other renovation and construction methods have been delivered to San Francisco Public Utilities Commission, Hong Kong Gas and the Ministry of Energy Water and Communications, Malaysia. Current projects include Rehabilitation Advisor to Wessex Water, Project Engineer, TBE Consortium, City of Largo Florida and technical advisor to Mouchel Parkman for the UKWIR large diameter mains failure study.

Sustainability

Dr Samuel Ariaratnam is currently the Vice-Chairman of the ISTT, as well a Professor at the School of Engineering at Arizona State University and has been a keynote speaker at many trenchless events all over the globe. Dr Ariaratnam’s presentation promises to be a highlight. He is no stranger to Australasia and his last presentation at a major event down under was at the 2006 International No-Dig in Brisbane.

Dr Ariaratnam is one of the world’s leading trenchless academics, his research is in the area of “÷Sustainable Urban Underground Infrastructure Systems’. He has recently undertaken ground-breaking research on the use of optimisation techniques and performance models to evaluate and develop improved construction strategies/methods for installing, assessing, rehabilitating, and repairing underground infrastructure systems including sewer/water systems, fibre-optic cables, pipelines, electrical lines, and gas lines. Particular focus is in trenchless engineering applications of HDD, pipe replacement, and underground asset management.

Well-known as a trenchless guru, Dr Ariaratnam has played a key role in raising the profile of the industry through his tireless promotional efforts. He is an engaging and entertaining speaker and his speeches are always a highlight. His experience and contacts mean that he has a strongly international perspective on the trenchless industry and is well versed on the varying local conditions that affect the sector.

His professional experience ranges from time with the United States Army Corps of Engineers to copious publications in refereed journals and conference papers. He serves on numerous boards and panels making various technical and funding decisions. Additionally he has consulted to many major companies and municipalities and has acted as a professional witness in many legal cases. Dr Ariaratnam also holds a number of patents.

Lessons from Singapore

Tan Thai Pin is the Director of the Water Reclamation (Network) Department, PUB,
Singapore. He will draw on his extensive experience in the water industry for the benefit of the Trenchless Australasia Conference delegates.

Mr Tan graduated from the National University of Singapore with a Bachelor of Engineering (Civil). He has been working in Drainage Department and Sewerage Department, Ministry of the Environment, since his graduation in 1982, and in the PUB since 2001.

His professional experience covers a broad spectrum of water and wastewater management. This includes the development of master plans, policies and also engineering works covering planning, design, construction, operation and maintenance of drainage, sewerage and water reclamation infrastructures. He has been involved in the use of Trenchless Technology for the installation and rehabilitation of sewers since the early 1990s.

He has also been intimately involved in the NEWater (high grade reclaimed water) development initiatives since 2001. His roles in the water reclamation initiatives have included participating in the NEWater pilot study, the implementation of the NEWater projects and the operation of the NEWater Factories. He has extensive knowledge in the planning, design and operation of large scale, high grade water reclamation plants using dual membrane technologies.

Mr Tan has presented papers at international conferences held in the USA, Europe, Australia, Middle East, India, Hong Kong, and Singapore sharing PUB’s experience in integrated water management and the use of advancement technologies.

Mr Tan said “It’s always a challenge managing Singapore’s water supply due to our limited resources, especially in our land area which is required for the storage of the rainwater. We therefore have to adopt an integrated and long term approach in our water resource planning.

“Ensuring that we have an adequate sewerage reticulation system is key to our water resource management for long term sustainability in water supply, both in protecting the quality of the raw water in our water courses and in capturing the sewage for treatment and water reclamation.

“PUB has been using trenchless technologies for implementation of sewerage network projects to serve new development and for the implementation of sewer rehabilitation plays. These technologies have enabled us to carry out these projects in a cost-effective manner and with minimal disruptions to the public.

“I look forward to co-operation with the utilities in Australia and to learn from them,” he said.

Building a future from water

Ross Young commenced as the Executive Director of the Water Services Association of Australia (WSAA) in 2004. WSAA is the peak body for the urban water industry and its members provide water services to 16 million Australians – 80 per cent of the population. As an industry insider Mr Young promises to be a highlight of the conference, he will present on the investment in the water industry, now and in the future.

Mr Young has extensive experience in urban water management at a senior level, having held a number of key executive positions with Melbourne Water for over a decade. During his time at WSAA, he has raised the profile of the Australian urban water industry and has established himself as the national spokesperson on urban water issues.

Mr Young is the Chair of the Global Water Research Coalition Board and a Board Member of WaterAid Australia. He has a Diploma of Horticultural Science, a Bachelor of Applied Science, an MBA and a Graduate Diploma in Natural Resources Law from the University of Melbourne.

Dollars and sense of No-Dig

John Roskam will be addressing the economics of Trenchless Technology and the economic drivers for infrastructure construction. Mr Roskam was a popular speaker at the Australian Pipeliner Industry Association 2008 Convention, addressing the economic outlook for both the pipeline industry and the nation. Mr Roskam is sure to bring unique insight and perspective to the economics of the trenchless industry.

Mr Roskam is the Executive Director of the Institute of Public Affairs. Before joining the IPA, he was the Executive Director of The Menzies Research Centre in Canberra. He has also held positions as Chief of Staff to Dr David Kemp, the Federal Minister for Employment, Education, Training and Youth Affairs, as Senior Advisor to Don Hayward, Victorian Minister for Education in the first Kennett Government, and as Manager of Government and Corporate Affairs for Rio Tinto.

His policy analysis includes reports such as Australia’s Education Choices (with Professor Brian Caldwell) and The Protocol: Managing Relations with NGOs (with Gary Johns).

Technical talk

In addition to the keynote speakers, a technical program offering two streams on a diverse and interesting spread of topics will engage and inform Conference delegates. The topic and themes of the technical papers will incorporate new installations, rehabilitation, replacement, inspection and assessment of all underground utilities including water and wastewater, as well as communications and energy. Local and international case studies will be presented along with papers in the areas of new and emerging technology, difficult environments, solving Australia’s water crisis, new issues in design and engineering, water re-use, pipe materials and tunnelling. Non-technical topics of interest include industry skills shortages and training, contracting strategies, risk management and projected capital works by utilities.

Trenchless on show

The exhibition will feature more than 50 individual companies from all areas of the industry, including contractors and equipment providers in areas such as HDD, tunnelling, relining, pipe bursting, concrete and plastic pipe manufacturers and consultants. This year the lively and colourful exhibition will be held in one area, adjacent to the Conference. The coffee cart with professional barista, sponsored by Parsons Brinckerhoff, will be located in the exhibition hall.

Making the most of Melbourne

Melbourne itself will be abuzz with footy fever, in the lead-up to the AFL Grand Final, taking place on Saturday 26 September. The conference takes place at the end of the third and final week of the AFL finals. The grand final parade will be held on Friday 25 September. Watching the city gearing up for what is one of Victoria’s biggest sporting events is truly a sight to behold.

Venue

The event will be held at Melbourne Park Function Centre, close to the heart of the city. The Centre offers first-class facilities and spectacular views of the city skyline. The Function Centre is ideally located for transport accessibility, next door to two tram stops (route 70), a taxi rank and two pedestrian bridges linking Melbourne Park with the Melbourne Cricket Ground. There is ample accommodation available at the nearby Hilton on the Park and Mantra on Jolimont, which is just a short walk from Melbourne Park.

Social Program

Take a trip to the lush and scenic Ivanhoe Golf Course for the Great Trenchless Golf Challenge of 2009 – a leisurely or active game of 18 holes on Sunday 20 September. Both serious golfers and weekend whackers will be welcome. Lunch will be available for purchase from the golf courses cafe after the ninth hole, and a drinks cart at cost will be on hand. Experience Melbourne’s beautiful colours and spring weather in a day of fun and entertainment, a series of prizes will be awarded, including outright winner, longest drive, and nearest the pin.

The Exhibition Opening Cocktail party will officially kick off the Conference on Sunday evening as all delegates and exhibitors gather together in the exhibition area to enjoy canap̩s and a range of drinks. Meet old friends and make some new ones as the event officially gets underway, 5 pm Sunday 20 September.

One of the highlights of last year’s conference was the spirited and scenic boat cruise. This year the Vermeer River Cruise will be departing from the Docklands for an enjoyable evening of drinks and a delicious buffet dinner, beginning 7 pm Monday 21 September. Like last year, the event is dress-up and this year’s cruise will be gangster-themed so scratch up your best Scarface. From Bugsy to Capone, all guys and dolls are in for a spectacular and decadent night of fun. And Melbourne’s recent brush with Underbelly should attract another colourful cast of costumes and characters to the event.

The prestigious Gala Dinner, Tuesday 22 September at the MCG, will be the trenchless industry’s feature event for 2009. Sponsored by Interflow, the glamorous evening will include an awards ceremony, top-class entertainment and a sumptuous three course meal. This is a very exciting time in the lead-up to the AFL grand final; enjoying the same venue will only add more celebratory spirit and dynamism to the Conference. This highly enjoyable and lively night is not to be missed and provides a great opportunity to socialise before having to say goodbye on Wednesday.

Tourist information

Melbourne is a dynamic, multicultural and versatile city with virtually endless activities and entertainment on offer. Whether you are looking for an animated, energetic activity in a bustling environment or a quieter, more tranquil place to unwind, there is no chance of boredom in a town that has something to suit everyone’s tastes.

Melbourne’s many shopping options are varied and colourful; from hidden laneways to large outlets, to trendy designer boutiques and arcades. There are also a number of unique fruit, food and merchandise markets throughout the city, many of which boast an incomparable experience of Melbourne’s multicultural face. If you prefer to be shown around, there are fun and informative guided walks that point out different shopping points. For discounted designer stores there is the Spencer DFO located at Southern Cross train station. If you are looking for boutique stores and high end designer stores, take a walk down Chapel Street, Prahran and South Yarra. Bourke Street is also a popular and fashionable destination.

Queen Victoria Market is Melbourne’s premier open-air market. Located just outside the city centre, the market has everything to offer; market stalls, food, wine, regular cultural activities and more.

Enrich your understanding and appreciation of Victoria’s culture, history and natural environment by visiting the Melbourne Museum, located in the picturesque Carlton Gardens. Museum highlights include Bunjilaka – the Aboriginal Cultural Centre, and the IMAX Theatre. Opening hours are from 10 am until 5 pm daily.

The Melbourne Aquarium houses over 10,000 aquatic creatures and is Australia’s only Southern Ocean Aquarium making it a must see. The Aquarium is open from 9.30 am until 6 pm daily. Crown Casino is filled with a wide variety of entertainment options; from shopping to gaming machines to different restaurants, you will find ample diversion. You may also want to take a walk along the swanky Southbank district, which is just outside of the casino, on the banks of the Yarra River.

Take a walk in the Botanic Gardens and look at over 10,000 species and 50,000 individual plants or enjoy relaxing splendour in the grass reading a book. The gardens are recognised as one of the world’s finest botanical arrays, with 38 hectares to explore. Open daily from
7.30 am until 6 pm.

The Eureka Tower is new to Melbourne and is currently the tallest apartment building in the world. The tower also has a lookout to the city, which is open from 10 am until 10 pm with last entry at 9.30pm. The Docklands is one of Melbourne’s new up and coming entertainment districts, with cosmopolitan restaurants serving fine cuisine, and a range of retail stores.

Day Trips

If you are interested in a day tour, the Great Ocean road is an unbeatable option. Enjoy breathtaking views while travelling down one of Melbourne’s best known tourist spots. You may even want to see the Twelve Apostles. The Great Ocean road is one hour out of Melbourne so you will need to hire car or book a day tour, which can be done at www.melbournetours.com.au.

Another great day trip would be a visit to the Yarra Valley wineries. Enjoy a day of wine tasting and socialising, as well as a gourmet lunch. The Yarra Valley is one hour out of Melbourne so you will need to hire a car or book a day tour which can be done at www.yarravalleywinerytours.com.au.

TT Asia Pacific and Tenix build partnership

Tenix Maintenance Services, part of Tenix Alliance, is responsible for the installation of gas supply lines in western Victoria. Manager Jacob Bonisch welcomed John Walsh and Denis Vout from TT Asia Pacific and, they discussed the machinery, the relationship between the companies and the growth of the trenchless industry.

Mr Bonisch said “Along with our horizontal directional drills, earth displacement hammers form an important part of our trenchless capability. Having a variety of effective trenchless options is an important part of our commercial success in the modern marketplace.”

The selection

There are many different earth displacement hammers on the market. What made Tenix Maintenance Service choose TT Asia’s Grundomat machines? Mr Bonisch explained that an important component of the selection process was a side-by-side trial in a variety of soil conditions. Three hammers were trialled, comparing the time taken and the accuracy of the equipment.

“The genuine Grundomat earth hammers were the stand out performers. The Grundomats left the other two for dead. For us, it was a reasonably obvious choice in terms of actual time on the job,” said Mr Bonisch.

“While the Grundomat was not the cheapest option in the market, our driver was a total life cost that took into account the time savings in completing the bores in the field, the frequency of required servicing and the lifespan of the asset.”

The speed of the road crossing and the availability and reliability of the machines was an important factor in the selection process.

Other than a shovel, the earth displacement hammer is the most common tool on the Tenix Maintenance Service truck. Every truck has at least one Grundomat and some trucks are running two for the different sizes – 55 and 75.

In choosing the genuine Tracto-Technik Grundomat product, Tenix Maintenance Service reduces the long term costs as the hammer has been proven reliable and accurate.

“For us, time is money. A crew that is constantly waiting for repairs on earth displacement hammers is not an acceptable or productive outcome. We need strong performance and reliability from our trenchless tools,” said Mr Bonisch.

Tenix Maintenance Service is equipping its maintenance trucks with the Grundomat earth displacement hammer. The delivery of 46 hammers will ensure efficient and effective installation of gas supply lines.

In business

The business relationship ethos of both companies is founded on a desire for long term mutual benefit. Mr Bonisch says that in business, companies can choose to make a lot of money over the short term or companies can aim to make a reasonable amount of money over a very long time period. “We, at the heart, are a relationship company and with our clients we build long term relationships,” he says.

For example, Tenix Maintenance Service has had the same material provider and the same plant provider for six years. In recognition of the reality that their suppliers need to make a profit and stay in business, Tenix Maintenance Service values long term relationship over short term cost cutting.

“At both our customer end and our supply end we try to build long term relationships,” says Mr Bonisch.

In response, TT Asia Pacific National Sales Manager John Walsh commented that it is progressive, intelligent companies that choose to purchase TT Asia Pacific’s German manufactured equipment – companies that rely on the quality, durability and reliability of TT products. “You can not afford to have this type of machinery fail underground,” says Mr Walsh.

The trenchless advantage

Mr Bonsich explains that the company views trenchless as the way to go, due to the demand of councils, consumers, residents and other stakeholders and various environmental constraints. “This is why we are manning up in terms of our trenchless capability. We recognise that earth displacement hammers, such as the Grundomat, are an essential part of being both cost effective and time effective in terms of getting things done and also keeping the various stakeholders happy,” he says.

Mr Walsh highlights the benefits of Trenchless Technology for companies such as Tenix Maintenance Service, companies which are responsible for installing essential services such as electricity, gas and water.

The Grundomat enables Tenix to install gas supply lines under roads and driveways. The hammer can enter off the street, under fences and landscaping, eliminating the need to remove paving and other hard made services that are expensive and time consuming to reinstate.

“The Grundomat takes away the necessity of digging up people’s driveways or roadways. It will cut inconvenience. Once you have bored under a road with a Grundomat there is no ongoing maintenance,” says Mr Walsh.

The average drive with the Grundomat takes 30 minutes per 12 metres, depending on soil conditions.

The trenchless option also significantly reduces the cost of the job. For example, the cost to reinstate a concrete driveway is approximately $A175 per square metre. “So to be able to put a service in without having to have any reinstatement costs is a massive commercial benefit,” says Mr Bonisch.

In the future

Tenix is looking to use the earth displacement hammer across other applications, for example in an electrical environment to put in conduit, to supply domestic electricity and to install fibre-optic cable. Tenix Maintenance Services is currently in discussions with Tenix Alliance Power. Tenix Alliance Power does approximately 100 road crossing applications per month.

Mr Walsh believes that TT Asia Pacific and the trenchless industry in general will continue to expand in Asia and Australia.

“In Australia communications and essential services will continue to grow [despite the economic downturn], and therefore the trenchless industry will also continue to grow,” he says.