The Diamond Harbour submarine water pipelines run across Lyttelton Harbour from Lyttelton to Diamond Harbour. The pipelines are twin 180 mm diameter HDPE pipes with concrete blocks for stability. Stability problems were experienced with the pipelines in 2009 when several blocks were found to have fallen off. The pipelines were stabilised by OCEL designed screw anchors. The Chilean tsunami in February 2010 caused the pipes, initially separated by 50 – 75 m to come together and entwine over a length of 210 m. Where the pipes had been stabilised by screw anchors no movement occurred. The entwined pipeline lengths were cut out and replaced by 400 m long sections and the pipeline rendered tsunami proof by installing screw anchor pairs at 50 m centres along each pipe.
Client Christchurch City Council, Contractor N-Viro Limited. Work completed 2011.