Second Power Generation Unit Nears Completion at Karāpiro

Mercury has achieved a major milestone in its three-year, $90 million upgrade of the Karāpiro Hydro Power Station on the Waikato River. The second of three new power generation units is nearing commissioning, with work on the third and final unit set to commence in October.

A critical step in the project involved the installation of a replacement water intake gate at the top of the Karāpiro dam in July. This gate, a vital safety feature protecting the new generator, is the second of three being replaced after more than 75 years of reliable operation.

The new gates were meticulously constructed at Ashhurst Engineering & Construction, with each gate requiring a dedicated team of six people approximately one year to fabricate. Weighing 40 tonnes and measuring 8 meters wide, 6 meters high, and 0.75 meters deep, the gates showcase AEC's capability in handling large-scale, complex engineering projects.

Transporting the gate to the dam surface involved a heavy haulage steerable axle trailer equipped with a custom support cradle. Precision engineering ensured the gate was successfully lifted and fitted into its guide rails. A hydraulic system will control the gate’s operation, allowing for smooth raising and lowering within the dam.

Once the gate is installed, rigorous testing will begin to commission the second power generation unit, expected to be completed by late August. This milestone will bring two of the three upgraded generation units online, enhancing the station’s output and reliability.

The wider upgrade project will increase Karāpiro’s generation capacity from 96MW to 112.5MW, adding 32GWh annually—enough to power 19,000 homes. The upgraded units will ensure the station continues to generate renewable energy for another 50 years.

Ashhurst Engineering & Construction is proud to contribute to this significant infrastructure upgrade, showcasing our expertise in delivering innovative and large-scale engineering solutions.