Engi­neer­ing ‘com­plex as brain surgery’

South Waikato News - - FARMING -

State-owned en­ergy com­pany Trans­power is on track to flick the switch on the ma­jor new power line run­ning from Whaka­maru, near Taupo, through the Waikato to Auck­land.

“The $824 mil­lion North Is­land power grid up­grade is on tar­get for com­mis­sion­ing in Novem­ber,” Trans­power Al­liance project man­ager Ian Ditch­field said.

Only about 50 of the 426 py­lons re­main to be strung with power lines, work that in­volves he­li­copters fly­ing back­wards for some of the time.

The up­grade has been un­der way since 2009, with the phys­i­cal work expected to be com­pleted in Septem­ber. Fi­nal test­ing will be car­ried out be­fore the lines are turned on in Novem­ber, with the power fed into the power grid ser­vic­ing the up­per North Is­land.

The project won an en­vi­ron­men­tal award this month in the Deloitte En­ergy Ex­cel­lence Awards.

The work on the new power line is be­ing car­ried out by Trans­power Al­liance, a group­ing of Trans­power, Bal­four Beatty and United Group.

“The work was al­ways go­ing to be a tech­ni­cal and en­vi­ron­men­tal chal­lenge,” Mr Ditch­field said.

The project in­volved more than 300 landown­ers, nine coun­cils and six gov­ern­ment agen­cies. More than 180,000 cu­bic me­tres of earth were moved. About 156 hectares of ex­otic for­est and 216ha of veg­e­ta­tion were cleared to make way for the py­lons.

‘‘Care­ful en­vi­ron­men­tal plan­ning, mon­i­tor­ing and com­pli­ance have all been part of the suc­cess of the project,’’ he said.

“More than 2460 trees and 14,893 shrubs have been planted in mit­i­ga­tion. The project also ac­tively sought to re­duce car­bon emis­sions, and to min­imise the im­pact on com­mu­ni­ties.”

Trans­power worked closely with re­gional coun­cils, the His­toric Places Trust and iwi rep­re­sen­ta­tives over on­site work re­quire­ments.

“That early and on­go­ing con­sul­ta­tion was ex­tremely im­por­tant throughout the project, en­abling faster pro­cess­ing of man­age­ment plans, sed­i­ment con­trol plans, site spe­cific con­sents and per­mits for con­struc­tion ac­tiv­ity,” Mr Ditch­field said.

Dur­ing con­struc­tion, ex­ist­ing farm tracks were used where pos­si­ble, re­duc­ing land dis­tur­bance. Those that were made be­came as­sets to the landown­ers who will be able to use them af­ter the project is fin­ished.

When veg­e­ta­tion needed to be cleared, a “stay on the farm” ap­proach was used so that cleared veg­e­ta­tion was not go­ing to waste.

It was made into ei­ther land­scape mit­i­ga­tion mulch for sed­i­ment bar­rier con­trol, milled on­site and used for fenc­ing, do­nated to lo­cal schools or stock­piled for the landowner.

Earth­works were re­duced by us­ing dura mat for tem­po­rary tracks, and a tracked Lo Drill rig that could

Care­ful en­vi­ron­men­tal plan­ning, mon­i­tor­ing and com­pli­ance have all been part of the

suc­cess of the project.

– Trans­power Al­liance project man­ager Ian Ditch­field

op­er­ate on an­gled slopes was used when pre­par­ing foun­da­tions.

Spe­cially ex­tended and crane-sus­pended con­crete pump hoses were used to pour the foun­da­tions.

En­vi­ron­men­tally friendly oils were also used to pre­vent con­crete stick­ing to the form­work so con­tam­i­nants would not dis­charge onto the land, he said.

The large-scale up­grade also in­volved some tricky elec­tri­cal engi­neer­ing op­er­a­tions, in­clud­ing the largest and most com­plex of its type in New Zealand de­scribed as be­ing as com­plex as brain surgery, Mr Ditch­field said.

This large op­er­a­tion re­quired a tem­po­rary power line, known as a by­pass, to be built on a Mor­rinsville farm near the point where the new line crossed the ex­ist­ing power line run­ning from the Hamil­ton to Coro­man­del line.

This was to en­sure power con­tin­ued to get through to Coro­man­del and sur­round­ing ar­eas while live power lines were strung on the new line.

The up­grade project was con­tro­ver­sial when first mooted, be­cause af­fected Waikato landown­ers did not want power py­lons march­ing across their prop­er­ties.

There were also con­cerns among some that the Waikato was be­ing ‘‘used’’ to ser­vice Auck­land’s power needs.

A board of in­quiry was set up, and de­ter­mined the project could go ahead. Trans­power ne­go­ti­ated ease­ment pay­ments with each af­fected landowner or bought prop­erty as re­quired.

It is un­der­stood some landown­ers re­ceived con­sid­er­ably more than $500,000 each, and some con­sid­er­ably less, de­pend­ing on the amount of their land in­volved.

Trans­power de­scribes the North Is­land grid up­grade as ‘‘su­per in­fra­struc­ture’’, to meet grow­ing elec­tric­ity de­mand for the next 100 years, pro­vid­ing sta­bil­ity of sup­ply in the Waikato as well as Auck­land.

ON TRACK: Trans­power on track to flick the switch on.

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