66kV Cable Replacement - Bromley Substation to Milton Substation
Civil Engineering
Surveying
Christchurch’s underground HV cables, now 40-60 years old, are still operational but increasingly vulnerable to seismic events. Orion undertook a major project to replace these aging cables, enhancing the city’s resilience. Our team played a critical role in surveying and designing 7.5 km of new underground cable geometry, navigating some of Christchurch’s busiest roads and intersections.
The project required crossing through Linwood Canal, composed of pre-cast concrete panels, and navigating the top half of a brick barrel stormwater system while preserving its structural integrity. We collaborated with Orion and various specialists to design and implement custom solutions that addressed these complex challenges.
The project traversed various ground conditions, including sand, clay, and gravel, presenting significant dewatering challenges. We delivered detailed plans, long sections, clash detection, and trench alignment design. This included the precise identification of services, and the strategic placement of new services to avoid conflicts, while adhering to necessary grades and design specifications.
Our surveying team meticulously located existing services, identified and mapped them, and ensured they were integrated into our plans. We conducted clash detection, compared existing services to the intended trench actions, and designed the trench to avoid service conflicts. Work on Brougham Street required compliance with NZTA standards rather than local council specifications, particularly concerning road seal requirements.
The project was a category winner for projects between $5m and $20m at the 2024 Civil Contractors New Zealand Construction Excellence Awards.
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