Abstract
The Avoca Lagoon Trunk Main Renewal Project was a $3.9 million sustainable infrastructure initiative delivered by Eire Constructions for Central Coast Council. It addressed urgent operational issues arising from ageing water mains, replacing deteriorating DN450 cast iron cement-lined and mild steel cement-lined trunk mains beneath Avoca Lagoon with a DN560 polyethylene pipeline installed via horizontal directional drilling (HDD) technology. This future-proofed upgrade ensured a continuous and reliable water supply for 11,000 residents across the Central Coast of NSW. The project stands as a benchmark for trenchless infrastructure delivery, combining innovative engineering, environmental stewardship, and strategic community engagement to achieve critical utility upgrades with minimal disruption. It demonstrates how compact HDD rigs can be deployed in urban and environmentally sensitive areas while protecting high-value ecosystems, including the habitat of the endangered Green and Golden Bell Frog. The works significantly reduced the risk of lagoon waterway contamination from pipeline failures, delivering long-term social, economic, and ecological benefits. Key objectives included ensuring water supply reliability, minimising environmental impact, reducing system redundancy, and increasing transfer capacity—which were achieved through careful planning, stakeholder collaboration, and precise execution. Comprehensive community engagement maintained public confidence, mitigated concerns, and facilitated smooth delivery in a highly sensitive location. As urban growth accelerates and environmental compliance tightens, the Avoca Lagoon Trunk Main Renewal Project provides a replicable model for best-practice trenchless delivery in Australia. Its outcomes reinforce the value of integrating technology, environmental care, and proactive stakeholder engagement in complex infrastructure projects. 1 No-Dig Down Under 2025 Avoca Lagoon Water Trunk Main Crossing Christopher Martlew and David Fox
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