What weighs about 270 tonnes, stretches nearly 16 kilometres and will take 18 road trips over three days?
The answer is a massive logistical challenge which will see 18 enormous drums of high voltage cable moved from Lyttelton into Christchurch where it will be used to strengthen the power supply to the north-eastern suburbs.
The 66,000 volt (high voltage) cables arrived into Lyttelton on Friday 21 September. This is Orion's largest cable purchase since 2000 and is stage one of a three stage project to deliver a more secure supply to eastern Christchurch. This three stage project is just one of $870m worth of projects planned over the next 10 years to improve and enhance electricity supply in the Orion network area.
The final destination for the cable is underground between Orion's McFaddens zone substation to Dallington zone substation. While that distance spans just over five kilometres of road, Orion will use nearly 16 kilometres of cable for the project. That's because it will use three lengths of cable to maintain a three phase system in the power supply network.
"This new high voltage underground circuit will mean a more secure power supply and fewer power cuts for those in the north-eastern suburbs of Christchurch," said Rob Jamieson chief executive of Orion. "Importantly for the rebuild of Christchurch, this circuit will be part of a high voltage power ring that will both restore the reliability of power supply and provide for growth."
The cable is split into sections each about 900 metres which are wound onto individual drums. "There will be 18 drums of cable to be transported from Lyttelton to Christchurch," explained Chris Birkett Managing Director of Christchurch based General Cable New Zealand Ltd.
"Each weighs around 15 tonnes and is nearly 4 metres high. Specialised low loader trailer units will be used but the choice of route is restricted by the size of the load. The Lyttelton tunnel is not big enough and Evans Pass is still closed due to the earthquake so the trucks will need to come to town via Gebbies Pass. We will be working closely with Orion throughout this project to support this important step in the Christchurch rebuild," continues Mr Birkett.
To minimise disruption, Orion is working alongside SCIRT who are repairing other underground services and roads along the same route. Mr Jamieson said, "This collaborative approach will mean fewer disruptions to our customers and create cost savings by avoiding digging up the road twice".
SCIRT has been contracted to excavate the cable route. Laying the cable is expected to begin in early October and finish in April 2013. "Those residents directly affected will have work notices put in their letterboxes in advance of the works beginning" says Duncan Gibb, SCIRT General Manager. "We are working with Orion and other utility providers to maximise opportunities for collaboration and cost-saving. It makes sense to do this whenever we can."