Transpower are planning to replace the power-converting equipment located at Haywards substation in the North Island and Benmore substation in the South Island to increase capacity across the Cook Straight undersea power cable.

The old power-converting units known as Pole 1 will be replaced with new state-of-the-art thyristor valve units known as Pole 3.

Before work can begin on the power-converting units the Haywards and Benmore substation sites need to be upgraded. Brian Perry Civil has the contract for this essential upgrading work, which will enable all other work to follow. The work includes seismic strengthening, constructing several retaining walls and developing a new switchyard layout.

The main challenges of the project come from the working environment within live switchyards. Very strict health and safety requirements mean all workers wear fire retardant overalls and gloves, and that they remove all watches and jewellery. All work must be performed with a Restricted Entry Supervisor in attendance.

Work progress in May 2010

1. Our first major milestone on the critical path was completed this month when we finished construction of Wall 11. Wall 1 has also been finished, and work continues on Walls 6 and 13.
2. The piling crew has worked steadily on preparing the walls for construction, and piling for Wall 6 was recently completed. Piling for Wall 5 has commenced in live switchyard A, and is giving the crew experience working around 110kV cables and underneath 220kV cables.
3. Wall 10 test anchors were completed this month and work has begun on that wall.
4. The site is a very busy one with other contractors going about their work. Transfield Infrastructure is making slow progress through the switchyard with the new watermain as existing services are not always located where plans indicate. Goodmans has commenced work on the replacement stormwater pipe but has been slowed by the wet conditions.
5. Testing of watermains is ongoing and final testing of pipes and manholes is complete.
6. We have produced a great new innovation to aid safety and communication on site. Around the site we have 4 mini-sheds that contain health and safety and emergency equipment, water, work plans, JSEAs and other useful documentation. We have daily briefs at each shed to cover the specific works in that area. The sheds have been very effective and popular, and we have named them ‘dogboxes’. Other organisations on site – among them Transfield and Transpower – are so impressed with the dogboxes that they want to use them on their own sites.

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