Stockton gas network upgrade strikes gold

The works involve inserting modern, high-density nylon piping into existing cast iron and high-density polyurethane (HDPE) gas mains.

This process, which derives its name from the yellow colour of the new piping, reduces the need to dig trenches in the street and will minimise safety and environmental risks.

“Rehabilitation of the Stockton network will minimise the likelihood of gas leaks or a loss of gas which sometimes happens when these old cast-iron pipes become rusted or the old HDPE gas mains start to crack,” said Jemena General Manager of Gas Peter Bowden.

The Stockton project is part of Jemena’s $A810 million investment over a five year period to upgrade and extend the Jemena Gas Network.

The Network distributes natural gas to over 1.1 million homes and businesses throughout New South Wales.

Safety with gas transmission pipelines

One of the major risks with horizontal directional drilling (HDD) is the striking of a utility line resulting in loss of life, property damage and social dislocation.

Historically, mechanical damage is the single largest cause of failures on pipelines.

Immediate failure typically occurs when construction equipment punctures the pipe and produces a leak at the time of damage.

Gas transmission pipelines from 300-1,000 mm diameter move large volumes of gas from gas fields to distribution networks. The pressure of gas in these lines typically ranges from 6 MPa (870 psi) to 16 MPa (2,320 psi). As a safety measure, pipelines are designed and constructed to handle much more pressure than is ever actually reached in the system. Pipelines in more populated areas operate at less than one-half of their design pressure level.

Pipelines are laid at depths of 1,200 mm (greater at crossings) in right-of-ways typically 25 m wide. Markers are installed to identify approximate pipeline location, but not pipeline depth.

Mitigation measures

Pipeline operators are increasingly demanding that risk assessments be made of drilling activity within the pipeline right-of-way to identify threats from drilling, and outline control measures to mitigate risks.

Mandatory measures have included:

  • A directional drilling plan to be prepared, outlining all drilling parameters and reviewed by pipeline operator;
  • Confirming DBYD pipeline locations by exposing pipelines using soft dig technology and further question those pipelines that might be missing;
  • In order to ensure minimum clearance between pipeline and drilling installation inspection/spot holes to be installed either side of the pipeline to monitor the drill head travel;
  • During the back reaming process, contractors should visually observe the back reamer passing an existing utility during pullback to ensure that potential reamer migration does not occur.

Never assume the location of pipelines. They can change directions abruptly and without any aboveground physical evidence (even between marker posts). Their depths vary, and more than one pipeline may exist within a right-of-way.

Multinet Gas project successfully commissioned

Work on the Lilydale Gas Pipeline included making changes to the Lilydale City Gate, which will reduce gas pressure from 6,890 KPa to 2,760 KPa to ensure the safe supply of gas to the downstream distribution network in August.

The new pipeline, owned by Multinet Gas, has been built to meet current and rapidly growing demand for natural gas in Lilydale, Chirnside Park, Croydon and locations across the Dandenong Ranges. The pipeline route required installation under the Yarra river, to overcome this barrier HDD was utilised.

The new 10 km transmission main will extend the Multinet Gas distribution network, which includes 9,800 km of pipelines and supplies natural gas to more than 660,000 residential, commercial and industrial customers.

Jemena was the construction contractor on the pipeline.

Tunnelling a shore thing for Chevron

The contract will involve Thiess constructing a 1.2 km long tunnelled shore crossing under the ocean. The tunnel will connect two offshore gas reserves to Chevron’s greenfield LNG plant at Ashburton North, near Onslow in the state’s north west.

The Wheatstone microtunnel will be 2.5 m in diameter and will be delivered by a tunnel boring machine (TBM) and lined by pipejacking. The microtunnel will accommodate a 1.1 m diameter pipeline to deliver gas from Chevron’s Wheatstone and Iago reserves.

Thiess Tunnelling General Manager Glen Ashton said “This is an exciting project for Western Australia and Thiess is committed to engage local suppliers and subcontractors, which will in turn boost local employment and training opportunities.”

Engineering and procurement commences immediately for the design of the TBM launch shaft, jacking pipes, and TBM retrieval pit. Construction on site will commence after the cyclone season in 2013.

Pipe insertion ensures Yarraville’s gas supply

SP AusNet, the manager of the Victorian gas distribution network across central and western Victoria, is replacing and upgrading 5.6 km of low pressure gas mains within and surrounding Urwin Street.

Where possible, high pressure polyethylene pipes will be inserted into the existing low pressure cast iron mains.

SP AusNet Manager Gas Services Dean Comrie said “This project forms part of a long-term effort to systematically replace cast iron mains across the existing network in our commitment to continually modernise and improve gas delivery to our customers.”

In 2011-12, SP AusNet will spend in excess of $A10 million replacing aged low pressure gas pipes. This project is anticipated to be completed by the end of October 2011.

Gas regulation brings change

A regulation intended to amend the Gas Supply (Safety and Network Management) Regulation 2008 was proclaimed on 1 July 2010, prescribing elements of the Dial Before You Dig scheme.

Under the new regulation, excavation works proposed by or on behalf of a public authority or involving excavation relating to the construction, repair or maintenance of underground utility services must follow certain procedures. For these works and any others requiring consent or approval under the Environmental Planning and Assessment Act 1979, it is now a legal requirement that the designated information provider for the scheme be contacted for information about the location and type of underground gas pipelines.

The regulation pertains to excavation works limited to the distribution district of a distribution network service provider. Certain works are exempt from the new requirements, such as minor excavations, excavations conducted under the Mining Act 1992 and excavation in an emergency. Owners of utility services and those working on behalf of them are also exempt from the requirements when excavating without machinery or power tools, or when urgent excavation is needed to stop water main breaks and leaks.

Enforcing the Dial Before You Dig scheme, if the gas pipelines information provided to the person carrying out the work contains a requirement to notify the relevant network operator, they must do so before the work is commenced or even authorised to commence. Information regarding the location and type of underground gas pipelines in the vicinity of proposed works must be requested within 30 days of commencing the work. The information gathered should be regarded whilst carrying out the work.

The WorkCover Authority’s Work Near Underground Assets Guideline forms part of the new scheme and must be provided to a person notifying network operators of excavation work, or the person carrying out the work. The regulation states the manner in which network operators must now be notified in the case of damage to underground gas pipelines caused by excavation work.

The amount of civil monetary liability of the designated information provider, or a person who is an employee or officer of or who is acting for the designated information provider, is now limited to a maximum of $A10 million for an act or omission relating to the provision of information under the scheme.

Trenchless Technology sparks the gas industry

Trenchless Technology is playing a vital role in the installation and maintenance of Australia’s gas transmission and distribution networks. The gas industry is benefitting from the advances and developments made by the trenchless industry.

This gas feature includes an overview of gas network projects across Australia, a review of the industry’s premier conference and in-depth look at the Devil Creek Development Project in Western Australia and the installation of the Paddington gas line in Sydney.

Gas in the pipeline

Jemena builds, owns, operates, develops and manages approximately $A9 billion worth of gas and electricity assets in Australia.

General Manager for Gas and Water, John van Weel in talking about the Trenchless Technology used in Jemena’s recent gas projects, said “In our view such methods are often preferable to open-cut work because they minimise the impact on the environment in general and in particular in built-up areas where such methods have less impact on local residents in terms of noise and/or local traffic.”


In Victoria, Jemena is rehabilitating parts of the Multinet Gas network, as well as being the project manager for the construction, operation and maintenance of the Multinet Gas extension programs in South Gippsland and the Yarra Ranges to meet growing demand for natural gas.

Jemena is undertaking between five to ten kilometres a year in horizontal directional drilling (HDD) and approximately 45 kilometres of pipe insertion work for the project. The program is to upgrade parts of its 9,400 kilometre gas network that delivers gas to some 660,000 homes and businesses in Melbourne’s inner, outer-eastern and south-eastern suburbs.

“Pipe insertion is the preferred method in Trenchless Technology in Victoria and it is how the majority of pipe renewal works are performed,” said Mr van Weel.

Currently Jemena is in the process of upgrading the Springvale South area, involving 16 kilometres of upgrade work. One of Jemena’s more recent HDD projects was in Mount Waverly where they constructed grid main and the drilling covered a distance of 1.2 kilometres.

New South Wales

In New South Wales, the company’s gas network provides natural gas to approximately one million customers in Sydney, Newcastle, Wollongong and more than 20 country centres – stretching
23,000 kilometres.

One of the largest HDD projects ever undertaken was the Sydney Primary Loop, a 30 kilometre pipeline linking Liverpool in Sydney’s southwest to Marrickville. The pipeline was built to improve security of gas supply and increase the capacity for long-term growth in both the eastern and the south-western regions of Sydney.

“HDD was used to overcome the challenges of laying a pipeline under rivers and in creeks without disturbing the natural environment and to minimise the impact on existing infrastructure,” Mr van Weel said.

There were a total of four HDD water crossings – Salt Pan Creek at Padstow, two crossings of the Georges River at the Casula and Hammondville and the Cooks River at Tempe. The Cooks River part of the project was interesting as it involved crossing beneath the existing secondary gas mains and the jet fuel supply to the Sydney Airport.


HDD was also used in Jemena’s project for the Canberra Airport Group (CAG). The company had to relocate a 100 metre steel gas main under the airport’s long-term car park and access roads to the airport. For this reason, an open-cut trench was not an option so under-boring over a distance of 220 metres was carried out. This project was part of the CAG reconfiguration of the airport.

Future projects

The company has started work on what will be one of its major projects in 2010 – rehabilitating the 350 mm diameter steel secondary main line between Wakehurst Parkway and Warringah in New South Wales. The line services increasing consumption loads along the length of Sydney’s northern beaches.

The Wakehurst Parkway rehabilitation project involves a cutting-edge solution requiring the insertion of high-pressure plastic pipe. Unlike previous rehabilitation projects on low and medium pressure sections of the network, where the length of the pipe inserted in each section is typically about 100 metres, the project will require inserting a 250 mm polyethylene pipe into an existing cast-iron main and then pulling it between 400 metres and one kilometre. Once in place the PV pipe will operate at a pressure of 1,050 kpa.

Jemena and HDD

Jemena has purchased a 330,000 pound HDD rig from Vermeer and this was utilised immediately on a number of their projects. Jemena’s HDD Manager Dave Warner said the drilling equipment available on the market today has transformed the quality of its projects.

Mr Warner said that proponents prefer to use HDD instead of trenching due to a number of environmental and social factors, which are attributed to the technological advances made in the industry and the improved quality of the pipe material that is used today.

“[HDD] has gone leaps and bounds in the last ten years. All the utilities are changing to polyethylene (PE) pipes, therefore making it more versatile for HDD as an option now.”

“The benefits of the PE pipe are a longer life span, and the durability of the pipe. Traditional pipes don’t have the guaranteed lifespan of what the PE pipe brings. That inherent capability of the pipe, coupled with the benefit of drilling lowers the impact to the environment.”

Mr Warner believes that as the environmental impact lessens, both the community and the proponent are kept in a positive frame of mind.

“There is less issue with community concerns and from a customer’s perspective; they don’t have as near as many complaints because you’re not digging up other people’s driveways. You’re going underneath and not disturbing them.”

FutureGAS 2010 fires up the industry

Over the three days, approximately 400 attendees visited the event to enjoy the exhibition and the broad speaker program, where delegates heard presentations ranging from the commercial to the technical, as well as project and operational updates.

Gas on the agenda

Queensland Minister for Infrastructure and Planning Stirling Hinchliffe officially opened the conference sessions on Wednesday morning by highlighting the state’s potential for natural gas development. Mr Hinchliffe emphasised the State Government’s support for proposed LNG projects, saying Queenslanders can look forward to “reaping the benefits of increases to gross state product, around the $A3 billion mark when the industry reaches its peak.

“We’ve consulted with industry and endeavour to get the policy settings right – ahead of the proponents’ final investment decisions.”

Transmission came into focus in the afternoon as Jemena’s Phil Colvin and Epic Energy’s Stephen Mudge provided updates on respective gas pipeline projects. Ross Gersbach from APA Group and the Australian Pipeline Industry Association’s Steve Davies considered the challenges and opportunities facing the gas transmission industry.

On Thursday, MWM Energy Sales Manager Simon Helps looked at the environmental issues associated with power generation, and how these can be alleviated by using cogeneration and trigeneration. Energy Conservation Systems’ Chris Flanagan later discussed applications for gas cooling systems.

Freehills’ Renee Garner looked at the proposed carbon pollution reduction scheme, and ways for gas companies to manage the risks involved with its implementation using contracts.

Focus shifted to natural gas for the domestic market as Jemena’s Peter Harcus gave an update on the “Natural Gas. The Natural Choice” campaign, which aims to reduce carbon emissions and promote the benefits of natural gas use to consumers in New South Wales.

Gas products on show

Companies such as PPI Corporation, Tremco Pipeline Equipment and Vermeer Sales and Services were among the 24 booths in the trade exhibition, which showcased the latest products, services and technology for the gas industry.

As well as delegates, more than 150 trade visitors ensured the exhibition was always buzzing. People took the opportunity in session breaks to peruse the stands and explore the latest products and technology.

Networking opportunities

The exhibition kicked of on Tuesday night with Opening Cocktails. Wednesday evening brought the Gala Dinner. Guests enjoyed a drink in the foyer before taking their seats, where they overlooked the city of Brisbane.

See you next year

Growing from the success of the inaugural conference in 2009, the 2010 FutureGAS Conference and Exhibition proved a chance for members of the industry to gather, reunite with old friends and make new contacts.

Event organisers Great Southern Press suggest you keep an eye on FutureGAS 2011, to be held in Brisbane in

March, as it is set to be even bigger:

Otway Gas Project – Microtunnelling retraction project

On behalf of the Otway Gas Project Venture, Woodside is developing gas condensate fields located off the south west coast of Victoria in the Otway Basin. The project involves installing a 20 inch gas export pipeline and a 4 inch service line between the offshore fields and a new onshore gas treatment plant.

Woodside awarded the HDD Shore Crossing to Drilltec Australia who engaged DJ & MB MacCormick Civil Engineering to undertake the microtunnelling retraction.

A key element of the project was the shore crossing where a microtunnelling retraction system installed a 1200 mm outside diameter steel casing in 6 m lengths, welded flush joints and wall thickness of pipe 20 mm at an incline angle of 17 degrees with an end location approximately 120 m below ground level. Once reaching this target location the machine and equipment was to be retracted back to surface.

The next stage involved HDD operations, using the casing to ensure no break out of drilling fluids/environmental impacts in these softer ground strata. Upon reaching the end of the casing, works continued approximately 800 m out to sea in more stable, harder ground and finished at sea bed level. From here, divers were to disconnect the equipment and attach the gas pipe for pullback operations.

The planning, design and procurement for the microtunnelling procedure took over ten months. This stage involved thrust shaft design, custom designing of weld joints and pipe, contingency planning, project specific quality, safety and environmental plans, testing the various ground stratas to ensure the lubrication mix was adequate, safety workshops in identifying potential hazards and risks and the development of action plans.

The process was undertaken by MacCormick in conjunction with Woodside, Drilltec, Eric Jas, Herrenknecht and Sinclair, Knight Merz. MacCormick awarded the supply and design of the specialised tunnelling equipment for the project to Herrenknecht and the design of the thrust shaft to Sinclair, Knight Merz.

The tunnelling equipment from Herrenknecht was tested in their workshops prior to shipping. The quantity of tunnelling equipment required for the project was considerable, with three 40 foot and two 20 foot containers required. Following the arrival of the equipment in Melbourne port, four hours of road transport to get to the project site was required. The shipment was then unpacked ready for works and retesting prior to use.

Within five days all containers had been unloaded, the concrete pad for the jacking rails constructed, the thrust block, entrance ring and gasket were placed and all cables, power, separation systems and tunnelling equipment were installed in the thrust shaft.

The project commenced on site from 6 December 2004, with shipping containers arriving on site from December 9. On December 14 the machine was launched and driven through the entrance ring.

The Project Manager for the tunnelling operations was Donald MacCormick. In risk analysis it was decided that works would be required 24 hours a day using two crews to ensure no risk exposure to high jacking tonnage which would have occurred if the machine had been stopped for any considerable time, increasing the friction of the pipes. A further consideration was that bentonite ports could not be placed along the pipeline, given the HDD operations required the internal casing to be flush smooth to ensure equipment did not catch on any obstacles during operations.

The works progressed at a rate of two to three pipes per shift, including the welding of pipe joints for each 6 m length of pipe.

On December 29 the final completion point of the microtunnelling operations was achieved and on December 30 the pullback system methodology was discussed with the work team and developed by JHA. At this point the jacking frame was changed to entrance wall for commencement of pullback. On commencing the pullback system the initial critical point was the shearing of the bolts, reached at 66 tonnes. All pullback tonnage after this was around 26 tonnes.

The equipment was removed at each joint location as the retraction works were completed during day shifts only. On January 3 at 10 am the tunnelling machine had returned to the thrust shaft. In total the operation was completed in 20 days.

Trenchless assisting Tasmanian natural gas roll-out

CDP Networks is currently completing construction of Stage 2 of the natural gas reticulation project in Devonport, northern Tasmania, which comprises some 120 km of polyethylene gas reticulation network. The system, when completed for asset owner Powerco Tasmania, will enable supply of natural gas to a potential 7,500 new consumers.

CDP Networks were engaged by Agility (now Alinta) to construct the project on behalf of Powerco. The project required a mixture of plant and construction methods due to the geology of the area. The client was keen to see as much of the project directionally drilled to ensure minimal reinstatement works were necessary, along with lower disruption residents along the route.

Around 75 km of the works were completed using two Case 6030 Drills and an Astec 3238 drill. These were set up as stand-alone, fully self-sufficient crews, supported with 1.5 tonne mini excavators, sullage trucks and associated plant.

CDP Operations Director Jim Connelly set a series of production targets for each crew, with crew leaders taking responsibility for planning and delivery of those targets. The teams were supported internally by CDP’s own traffic management planning and control crews, operating out of company’s Devonport base.

Flexibility was an important aspect of the works, given the ground conditions in areas of Devonport, and indeed across much of the state, contained rock formations with a compressive strength of 300 MPa.

Consequently, to ensure continued production, it was important for the CDP planners to prepare forward works which would enable a crew to jump across a rock area when encountered, to a new section able to be directional drilled.

The rock areas were then tackled by two special crews operating a 14 tonne Takeuchi and a 12 tonne Komatsu excavator with General Breaker rock hammers to deal with the rock conditions.

Given the relatively new approach of directional drilling for the installation of Tasmanian infrastructure, it was important for CDP to demonstrate from an early stage the reliability of the process, which would avoid third party asset damages. An independent asset locations team operated well ahead of the crews, working from “÷one call’ plans and carrying out all necessary provings to ensure each drill crew had a clear run once on site, and that any route or design changes were dealt with prior to arrival at site.

As a consequence of this focused approach two benefits have been achieved. Firstly, lower cost operations have resulted due to few delays, either by unforeseen damages or downtime awaiting design change approvals. This process also provided Powerco with timely notice for considering amendments, which in turn translated to a solid, professional relationship between the parties.

Secondly, other stakeholders, such as Devonport City Council, were able to gain confidence in what could have been an intrusive project for the community and recognised the HDD process can be productive whilst avoiding disruption through damage to their water and sewer assets.

Importantly, through this project, CDP has been able to successfully achieve a key objective in building a number of local teams, manned by Tasmanians, who through CDP training and experience, have been able to build a successful long-term opportunity in the new Tasmanian gas industry, and in some cases for the first time, are able to work in their home state.

CDP now has an office located in Victoria to expand their infrastructure installation expertise to Southern Australian markets, already completing 110 km of works to date.

Tallawarra gas pipeline project

The joint venture engaged UEA Pty Ltd to undertake HDD works including the boring and installation of
763 m of 272 mm steel pipe in rock rated up to 120 Mpa. UEA used its Vermeer D300 x 500 (136 t) as well as a DFE 700gal/min recycling system, and 700 gal/min Weatherford mud pump.

Site specific problems included varying rock strengths and fractured rock; depth to allow for clearance of bridge piers on the F3 Freeway, the bore was required to be at least 28 m deep; dealing with the requirements of State Rail for the Illawarra rail line crossing; and, tight tolerances imposed on the bend radius.

Pilot Bore

To assist in working to the tolerances a surveyor was engaged to peg out the route and verify the profile. Once this was completed the information was entered into the bore planner software and a profile was created.

Due to the tight time constraints and prior work commitments for its maxi drill, UEA decided to utilise its 25 tonne Vermeer D50 x 100 HDD machine to commence the pilot bore. Using an in-house Digitrak SST steering tool the initial 500 m was pilot bored in nine days. Upon verification of the alignment it was found to be incorrect due to a magnetised sonde housing which significantly affected the magnetometers within the steering tool. This pilot bore was then abandoned.

UEA then mobilised the Vermeer D300 x 500 and a new pilot bore commenced. This time a Paratrak 2 steering system was utilised to track the bore. The Paratrak system allowed very accurate monitoring of the bend radius throughout the pilot bore to ensure that the tolerances were not compromised. The geotechnical information stated that there was a likelihood of encountering clay approximately 80 m from the exit point. UEA stopped the pilot bore at this distance, pulled the rods out and set up to forward ream.

Throughout the pilot bore the ground conditions varied in consistency, a percentage appeared to be broken. With the varying ground conditions, Baroid’s experience was utilised to develop a successful mud plan to cope with the broken ground and deal with the large mud losses that were happening.

Forward Ream

A hole-opener with 16 inch medium formation cutters were used initially to forward ream the 700 m of rock. Progress throughout the reaming process was slow using the selected cutters and some experimentation was required with the cutter selection to reach an acceptable progression rate. To avoid large “÷frac’ outs in the clay section, the D50 x 100 was moved to the exit side and pilot bored down and intersected the initial 8 inch pilot bore created by the D300. An 8 inch sewer plug was placed in the hole so as to aid with the forward reaming process currently being undertaken by the D300. Once the rock section had been completed by the D300 it was remobilised to the exit side where it proceeded to forward ream the clay section. Once completed it was then remobilised to the entry side in preparation to pull the dummy pipe.

Dummy Pipe Pull

As part of the process for borehole approval, UEA was required to pull a section of dummy pipe approximately 36 m long. Once the pipe had been pulled in, it was inspected for damage and tested. The client was happy with the sample condition and the bore hole was approved for final installation of the product pipe.

Pullback of Product Pipe

The 763 m of gas pipeline had been placed on rollers in preparation for pullback to reduce friction during the process. The pulling head was attached to the drill rods the day before pullback. Pullback commenced at 6.30am and the pipe was pulled in over an eight-hour period. Throughout the pullback process the pipe coating was tested to ensure its integrity. Once the pipe pullback was complete, the pipeline was tested again. After a few anxious moments the pipeline passed the test parameters and the project was complete.


This project provided UEA with some significant challenges in particular steering tool and hole-opener selection. The project was completed within a few days of the required date of contract. UEA has said that the Nacap/Tru Energy joint venture was an excellent client to work with from the top down, in particular the management’s proactive approach to any site issues.

UEA is happy to have this project as part of its r̩sum̩ due to the length and the tight tolerances required for a steel pipeline. The project has provided the company with some excellent experience when called upon by future clients to undertake similar projects.