Rail corridors, highways and floods prove no obstacle for Pezzimenti Trenchless, who have successfully completed drilling of three bores as part of APA’s Victorian Northern Interconnect Expansion (VNIE) project.

Working under contract by Nacap Australia, engineers at Pezzimenti Trenchless saw the varied clay ground conditions as the least of their worries, with harsh weather and challenging crossings being greater obstacles in their path.

“Extreme weather conditions played a major role throughout the majority of the project,” said Pezzimenti Trenchless Director, Joe Pezzimenti. “Our team was faced with floods one day and hot, dusty climates the next, requiring diverse management of each trenchless operation.”

The month-long drilling contract saw Pezzimenti Trenchless completing a total of three bores followed by pipe jacking, pipe insertion and pull back. Each bore was 45m, 60m and 117m in length respectively, crossing beneath the Benalla to Yarrawonga Railway, the North Eastern Railway and the Goulburn Valley Railway.

“Drilling under the rail corridor was particularly challenging,” says Mr Pezzimenti, “not to mention carrying out highly accurate drilling beneath the Seymour-Avenal Highway. These are each high-traffic channels, meaning that there was added risk to consider.”

Each bore was 700mm in diameter and a tight tolerance of 10-15mm was required along the bore length.

“The 10-15mm tolerance was a must, as the gas pipe was required to be pulled back in one continuous string. There was also only 18mm clearance between the gas pipe, centralisers and diameter of the RC jacking pipe,” says Mr Pezzimenti.  To further centralise the pipe, kwik-ZIP HDX 38 spacers were used.

Sensitive native flora and fauna were also thrown into the mix, covering sections of the pipeline construction route. However, “great care was taken to ensure that correct management of these native sites throughout our operations were upheld,” said Mr Pezzimenti.

About the expansion

With LNG exports set to change the face of the Australian east coast gas market, the expansion of the Victorian Northern Interconnect by APA is aimed at alleviating supply pressures within the region. The expansion, to be completed by the end of 2015, involves looping sections of the existing pipeline to increase capacity, which will enable more gas to flow north into NSW from southern supply basins.

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