18 | REGIONAL WSP New Zealand SOLUTIONS Bridge Construction Design & Build Services Marine Construction Drilling & Anchoring Civil & Concrete Construction Three Waters Infrastructure Seismic Strengthening & Repairs Sheet Piling & Temporary Works 0 3 3 8 1 7 0 9 4 w w w . h u n t e r c i v i l . c o . n z T T Karen Phelps Blown away by a clever solution Three Vestas V27 wind turbines were installed at Point Durham using a ground-breaking modular precast concrete foundation system developed by WSP. “The constraints on the Chatham Islands meant traditional construction methods simply weren’t practical. so we had to develop a completely different solution.” An innovative wind farm project on the Chatham Islands has earned national recognition after overcoming extraordinary engineering and logistical challenges to deliver cleaner, more affordable electricity to one of New Zealand’s most remote communities. WSP, one of the world’s leading professional services firms, received recognition for its work on the Chatham Island Renewable Energy Project, where it acted as the primary design consultant, delivering structural, geotechnical and civil engineering services. The project was managed by Pachlan Engineering and delivered in collaboration with Hunter Civil and Independent Line Services to bring the award-winning development to life. “Winning this award reflects the willingness of everyone involved to challenge conventional thinking,” says Jamie Lester, technical director - structures at WSP. “The constraints on the Chatham Islands meant traditional construction methods simply weren’t practical. so we had to develop a completely different solution.” Designed for Chatham Island Electricity Limited, the $10 million project replaces a significant proportion of diesel-generated electricity with renewable wind power, strengthening energy security while reducing costs for the island’s approximately 720 residents. Three Vestas V27 wind turbines were installed at Point Durham using a groundbreaking modular precast concrete foundation system developed by WSP. “With no structural concrete batching plant or piling equipment available locally, conventional wind turbine foundations would have been prohibitively expensive and difficult to construct,” Jamie says. “Every major component also had to be transported around 800 kilometres by barge from the mainland, with strict weight limits applying to each shipment.” Instead, WSP designed a modular foundation that was manufactured in Christchurch before being transported to the island in sections, working with shipping logistics. The components were assembled on-site using an innovative post-tensioned huband-spoke system, eliminating the need for structural concrete pours, while making use of engineered local backfill as stabilising ballast. The innovative design has become the first known precast post-tensioned modular wind turbine foundation of its kind in New Zealand. “The modular approach reduced construction time significantly as well as improving quality assurance because the components were fabricated under controlled conditions,” says Jamie. “By optimising the design through detailed options analysis and parametric modelling, the project reduced concrete use by around 50% compared with traditional mass concrete foundations and lowered embodied carbon by approximately 20%.” Hunter Civil became involved early in the project providing valuable input into constructability and logistics that helped refine the modular concept before construction began. Independent Line Services also contributed to the successful delivery, ensuring the new renewable infrastructure could be integrated into the island’s electricity network. Jamie says the collaborative approach proved highly effective, with detailed modelling, early contractor engagement and regular communication helping minimise construction risks and reducing requests for design changes throughout the build. Since commissioning, he says the project has exceeded expectations. Renewable generation has already surpassed the original business case target of 65%, with recent months achieving 86% renewable electricity. Energy costs for Chatham Islands residents have fallen by more than 25% and diesel consumption and carbon emissions have been dramatically reduced. “This project has delivered a practical solution that improves resilience, lowers electricity costs and provides a model that could be replicated in remote locations across New Zealand.”
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