3.4km of pipe at 1,575mm OD and 11mm and 16mm WT

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The Cosseys raw water main is a critical connection within Auckland’s water supply infrastructure. The deterioration of two large diameter 1.9m and 1.5m pipes installed in 1950 necessitated replacement along a 3.5km-long route downstream of Cosseys Dam towards Hunua Village, south of Auckland.

The main project risk was the potential disruption to Auckland’s water supply which meant that all parties – Watercare, contractor Pipeline and Civil and Steelpipe – worked closely together to develop and deliver a plan that mitigated this risk. To ensure no delays, Steelpipe manufactured a large amount of pipe in advance, then managed the onsite storage and protection of the pipe, re-inspecting each section before it was laid. This was crucial to de-risking the project and the successful, on time completion.