Transpower's tower of power

TOWER OF POWER: Transpower's first pylon on its North Island grid upgrade, near Maramarua, is almost complete.
PETER DRURY/The Waikato Times
TOWER OF POWER: Transpower's first pylon on its North Island grid upgrade, near Maramarua, is almost complete.

Transpower calls it Tower 83.

But for the rest of us it's pylon No1 in the $824 million North Island grid upgrade, which is about to unfold as the largest electricity transmission line project undertaken in New Zealand since the 1960s.

Sometime in the next 24 hours, this imposing 64.1 metre high structure, built from 32 tonnes of steel and held together by 3240 bolts on a windswept 182 hectare dairy farm in Mangatangi, will become the first completed pylon in Transpower's new line.

By May 2012, it will be just one of 426 such structures dotting the landscape between Whakamaru and Brownhill Rd in southeast Auckland as part of the new 186km transmission line, which will be capable of conducting 400kV, though initially is due to operate at 220kV.

A team of six riggers have spent four days putting this pylon together like a giant Meccano set, after bundles of steel were trucked from a Matamata yard.

The initial assembly was done on the ground, with the bigger pieces lifted into place by giant cranes. Yesterday riggers were climbing all over the lattice work like a team of ants, bolting parts together.

Tower 83 completely dwarfs the aged 110kV Ari-Pak A line running next to it, which it will eventually supersede, while the second pylon, 200m to the west, is also half completed.

Once the stringing of the transmission lines starts next year, the four arms of the pylons will carry six phases of aluminium cables, an earth wire and fibre optic communications cable.

The project sparked bitter resistance, including effigy burning and threats of civil disobedience by some in their path, but Transpower's construction manager for aerial works, Eddie Lindstrom, speaks lovingly of them.

"They are our babies," he said. "They all have their own little idiosyncrasies and you get to know each one."

Construction is a complex job, with access and foundation work, upgrading of farm races, stream crossings, fences and culverts preceding assembly and erection, which generally takes six days per tower.

As winter sets in, Transpower will switch its focus to construction on the large dairy conversion farms and amid the Carter Holt Harvey forests in the South Waikato.

That's likely to give the Tokoroa economy a huge boost over winter with up to 80 contractors based in the town. On the evidence of spending patterns at the northern end of the project, sales of everything from meat pies to petrol will skyrocket.

Meanwhile the old Ari-Pak line (running from Arapuni to Pakuranga), which was constructed in the 1940s, is also due to be dismantled as part of the overall upgrade.

Waikato Times