Mighty River Power has achieved an international first with the successful completion of the technically challenging two year Arapuni Dam enhancement project.
The Arapuni Dam is the oldest operating power station on the Waikato River and at 186 megawatts has the largest generating capacity of any single station in the Waikato hydro system.
The $20 million project has attracted international interest as the first of its type to be undertaken while the dam remained full and operational.
Mighty River Power’s Hydro Generation Manager Gavin Williamson said the Company had greatly appreciated the support and ongoing patience of the community throughout the project, particularly as the road across the dam was closed while the project was undertaken.
The Company worked with a team of international experts and local engineers on a precision drilling programme to fix minor seepage which was first identified after the dam was built in 1929.
Mighty River Power took over management of the Arapuni Dam in 1999 and the enhancement project was part of ongoing work to ensure generation assets are maintained to high operational standards.
The work involved technicians drilling a network of small, precise interconnected holes up to 90 metres in depth from the top of the dam, which were then filled with concrete to stop potential seepage.
“It was even more challenging than we expected and a special guide and drilling system was developed to achieve the results needed,” Mr Williamson said.
The precision necessary combined with the discovery of unexpectedly hard concrete meant the drilling programme had to be extended by 12 months.
This year the enhancement project was awarded a Shell Environmental Excellence merit award at the New Zealand Contractors Federation 2007 annual conference which recognised the efforts taken to minimise the environmental impact of the work.
The project team consisted of Italian foundation specialist Trevi S.p.A and local engineering contractor Brian Perry Civil with specialist technical advice from DamWatch Services.
The local Arapuni community has been invited to a celebration with the onsite team on 23 October to mark completion of the work and the opening of the Arapuni Dam Road to traffic.