The Tasmanian Gas Reticulation project involves the development of a gas distribution network for Tasmania, with pipelines linking consumers to gas from the Tasmanian Gas Pipeline, which crosses the Bass Strait.
Powerco’s distribution network comprises of medium and low pressure pipelines that transport natural gas to homes and to small and large commercial operations. As the natural gas distributor in Tasmania, Powerco is also responsible for laying the gas pipe from the street to homes, installing meters and connecting customers to the natural gas network.
Powerco Tasmania General Manager Richard Sheather said Powerco was very pleased with progress to date with the uptake of natural gas looking encouraging.
“The latest figures show that more than 600 residential and smaller commercial customers are now connected to the natural gas network. There has been strong demand for gas with interest increasing all the time. For example, our 1800 information line is averaging more than 1,000 calls a month,” Mr Sheather said.
Mr Sheather added that about half of the rollout had been completed, with approximately 360 km of pipe installed. “The rollout is on track to be finished in all areas by mid next year.”
“The work has been challenging at times and featured some major achievements, including the construction of a 200 mm NB diameter X56 pipeline 949 m long horizontal direct drill 25 m underneath the bed of the Derwent River between the Hobart suburbs of Old Beach and Austins Ferry, the third longest in Australia to date.”
The high pressure pipelines have been constructed to supply the main cities of Hobart, Devonport and Launceston.
In south Tasmania, this has involved a 40 km pipeline running from the Bridgewater Offtake facility with a route involving approximately 10 km within the Pacific National railway easement.
The alignment takes the steel pipeline within 5 km of the main Hobart CBD area through urban streets before terminating at an underground pressure reduction station and pig receiver facility.
The pipe was mainly API5L X56 grade of varying wall thickness from 4.88 to 8.1 mm depending on its location.
The class #300 steel pipelines cross a number of other significant obstacles, including rivers, railways and major highways.
In the north the steel pipeline was 150 mm NB X42 and X56 predominantly yellow jacket pipe with a range of wall thicknesses from 4.8 mm to 7.1 mm.
The network will pass 38,500 Tasmanian homes by mid-2007.
A strong direct marketing campaign has been implemented and Powerco is working closely with the two gas retailers that have signed access agreements with Powerco, Aurora and Option One, and with Alinta, the transmission owner, to develop joint strategies to promote natural gas throughput.
Powerco began work on the project in May 2003 with the commencement of the design process.
The first stage of the project, which was completed in July 2005, involved the laying of 100 km of gas pipelines in the urban areas of Hobart, Launceston, Longford, Westbury, Bell Bay, Wynyard and Devonport.
Work also included the design and construction of eight gate stations and scraper stations, featuring the usual equipment such as metering, pressure control, gas heating, SCADA and electrical and instrumentation.
Powerco commenced construction work on the network to service smaller commercial and residential customers following the completion of the majority of stage one construction works.
The stage one network had to be largely in place to enable the connection of stage two.
Tasmanian natural gas network proves challenging
Constructing a natural gas network in the island state of Tasmania has presented a number of unique challenges, Build Manager Andrew Bambridge said.
Despite this, he said the challenges had been well managed by Powerco.
“This was a greenfields development so there was no existing infrastructure from which to base our network,” Mr Bambridge said.
“The stretch of water between Tasmania and mainland Australia (Bass Strait) also presented us with issues in terms of ongoing construction operations and maintenance.
“We have overcome this with the contracts we have in place with our contractors, and we have the ability to call on specialist resources or equipment if we require them. But the distance between Tasmania and the interstate resources has been a significant issue that we have had to manage.”
Mr Bambridge said Powerco’s network generally operated at a higher pressure than those interstate.
“These interstate-based networks vary considerably, with some operating at less than 100 kPa while others are up to 500 kPa,” he said.
“In Tasmania we are operating the polyethylene network up to 1,000 kPa to maximise the capacity of the pipeline. In Hobart and Launceston we have sections of network up to 250 mm diameter
SDR9 PE mains operating up to 1,000 kPa.”
Despite the numerous challenges, Mr Bambridge said he believed the rollout to this point had been successful.
“Proper planning was all important. Ensuring that the relevant stakeholders were consulted and selecting the correct route to maximise customer connections were obviously important considerations.
“In addition, Powerco has constructed large chunks of the network through an urban environment and the central business districts of the State’s cities, which has presented its own series of challenges in terms of road closures and reinstatement works.
“This has also been well managed and criticism of our works has been minimal,” he said.
Since commencing work in Tasmania on the natural gas rollout, Powerco has been keen to see skills developed in the state to underpin the long-term development of the evolving natural gas industry.
Mr Bambridge said the company wanted to maximise local participation in the rollout.
“There is an obvious skills shortage that needs to be addressed. When we first arrived it was necessary to bring in skilled labour from interstate. Today only a third of our workforce is interstate-based with the balance originating from Tasmania.
“Powerco employs four primary contractors – Agility, Tenix, BBS and Viegold-which subcontract to local machine operators, reinstatement contractors, plant hire companies,” he said.