We will begin a $6.74m project to replace the Glenbrook Beach watermain in early April. The original pipeline experienced a joint failure in January 2023, when half a kilometre of pipe dislodged and floated to the top of Taihiki Estuary between Waitete Pā and Glenbrook Beach.
Photo: The old pipeline being removed
As soon as the pipe broke, we asked residents to reduce their water usage until a temporary floating pipeline could be installed across the estuary, connecting the community’s reservoir to Auckland’s water network. Until it was installed in February 2023, we arranged tanker deliveries to top up the local reservoir and keep water running for local residents.
Photo: The temporary watermain being installed
Project manager Sean McHenry says twin water pipelines will be installed to provide additional redundancy. They will be constructed 15 to 20 metres underneath the estuary, using horizontal directional drilling (HDD), a standard drilling method commonly used to install underground cables and pipelines.
“Using horizontal directional drilling to install the pipelines instead of anchoring them to the seabed using concrete weights will reduce soil disturbance to the riverbed and environmental erosion.
“Installing them this way is less risky and has better health and safety outcomes as it eliminates the need for manually anchoring the pipelines to the estuary bed.
“Having the pipes underground also reduces erosion risk and the potential for ongoing pipe breaks.”
McHenry says, our construction partner CDS will station a drill rig on the reserve at Tahuna Minhinnick Drive at Glenbrook Beach.
“We’ll drill three 300mm holes four metres apart to the reception pits on the other side of the estuary at Waitete Pā on Wharf Road. The additional pipe is a wastewater contingency one which may hopefully never be required.
“The drill rig stationed at the reserve at Tahuna Minhinnick Drive will pull the new polyethylene pipelines through the 300mm holes underneath the estuary from its assembly point in Waitete Pā.”
McHenry says the replacement pipelines will be installed near where the original pipeline broke and will connect in with the established connection points on Wharf Road and Glenbrook Beach.
“The new pipelines will run underneath the estuary in a straighter line to improve resilience and reduce the likelihood of pipe breaks. They will supply more water to the community, support population growth and development proposed for the area.”
We estimate that the replacement pipelines will be operational and the temporary pipeline will be removed by the end of October.
McHenry thanks the community for their patience while we devised plans for a permanent replacement pipeline. “We have spent time ensuring that we could develop a permanent solution that worked for the community and local iwi and provided future resilience for the Glenbrook Beach area.”