Jemena has recently announced plans to make some key upgrades across its NSW gas network, proving that gas pipelines can be given a new lease of life with the right relining technology.

In Bowral, in the state’s Southern Highlands region, the utility recently embarked on a project to upgrade the town’s gas network, rehabilitating 11km of gas distribution mains using a technique which involves inserting modern, high-density nylon piping into existing gas mains – such as old cast iron mains and old high-density polyurethane (HDPE) gas mains.

This process reduces the need to dig trenches in the street. This trenchless technique also minimises safety and environmental risks as work is often carried out in the vicinity of busy roads and other utility infrastructure.

By undertaking the rehabilitation process, Jemena is able to upgrade the capacity of the network – for example from 7 kilopascals (kPa) to 210kPa of pressure. This also results in the replacement of any existing customer’s meter set, and in some cases, the service pipe from the street to the home.

By increasing pressure in the Bowral gas network, Jemena is able to increase supply in the event of existing and future customer demand, and to cope with the customers using new gas related-technologies, such as continuous flow water heating systems.

Managing the network during rehabilitation

Jemena has been managing the process of rehabilitating the Bowral gas network by rehabilitating sections of approximately a few hundred metres, or one street at a time. Generally such work takes only a day, so only those customers in a particular section or in a particular part of the street will be without gas supply until such time as the work has been completed.

For commercial or vital services such as hospitals, Jemena For commercial or vital services such as hospitals, Jemena is able to maintain gas supply through alternative supply methods. Standard practice is to notify customers on three separate occasions before commencing any works – one month prior, 14 days in advance, and again the night before work commences.

Planning is essential in order to maintain supply to customers while upgrading the gas network. The work is highly specialised with only a handful of contractors able to carry out the works.

“Rehabilitation of the Bowral 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 Peter Bowden, Jemena’s General Manager, Gas.

“Rehabilitation will also ensure the Bowral network is able to cope with growth in demand for natural gas which is driven by the increasing number of homes and businesses in the area using natural gas and the increasing use of gas appliances,” he added.

 Improving gas supply in Sydney’s CBD

In addition to the rehabilitation program taking place in Bowral, Jemena has also announced plans to lay a new gas main and build a new gas interconnection facility to ensure the reliability of supply to 90,000 homes and business in the Sydney CBD and inner-city suburbs.

While construction activities will only start in early to mid-2015, during May Jemena has been making contact with residents in all streets that will be affected by the work.

“This is part of our standard approach to engaging with stakeholders – be they existing customers or residents whose homes will be passed by the new gas mains,” said Alf Rapisarda, Jemena’s Executive General Manager, Networks and Pipes.

“Jemena will start sending a notification to all affected residents about the project in early May. This notification will include a survey form that residents can fill in and return to Jemena. This survey form is designed to help Jemena better understand each resident’s situation before we start work on the project next year.

“Our aim with projects such as this one is to ensure reliability of gas supply to homes and businesses, as well as to cater for future growth in demand for natural gas from industrial, commercial and residential customers,” said Mr Rapisarda.

The new gas main and interconnection facility will built using open-cut techniques, with contractors involved in the project currently being finalised.

On the rehabilitation agenda

The Bowral rehabilitation project is one of many that are part of Jemena’s $810 million investment over a five-year period to upgrade and extend the Jemena Gas Network.

This investment is aimed at ensuring more homes and businesses can enjoy the benefits of natural gas, ensuring the reliability and integrity of gas supply to homes and businesses and at meeting the growing demand for natural gas as customer numbers grow each year.

“Each year we add another 30,000 customer sites to the Jemena Gas Network in New South Wales.  Since 2005/2006, the total number of homes and businesses connected to the gas network has increased by 160,000,” said Mr Bowden.

Since 1987, Jemena has rehabilitated almost 6,000 km of gas mains – which represents almost a quarter of the 25,000 km-long Jemena Gas Network which distributes natural gas to over 1.2 million homes and businesses throughout New South Wales. Jemena maintains a detailed seven-year project plan with an overall view to 20 years. In keeping with the plan, sections of Sydney and Blacktown are next in line for rehabilitation works.

Jemena places high importance on maintaining/upgrading their network, because it is their responsibility to ensure its customers receive safe and reliable supply of gas and to replace and upgrade ageing parts of the network. This is why the utility invests in laying new gas mains (approximately 200km of new mains each year to accommodate for growth in customer numbers) and why they operate a continual program of rehabilitation of existing assets.


Lindon Ball (left), the Bowral project manager; Andy Magro, the construction supervisor; and Nathan Homes, Jemena’s area manager for Bowral and Wollongong, celebrate the successful completion of the project.

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