Cross-harbour pipeline investigations under way in Lowry Bay
Wellington Water’s barge and drilling rig has moved into Lowry Bay in the final stages of a series of geotechnical investigations in the harbour to help determine the best route for the Cross-Harbour Pipeline.
The Cross-Harbour Pipeline is a proposed major project to improve water supply resilience for the metropolitan region. It will provide an additional water supply pipeline that will cross Wellington Harbour from Lower Hutt to Wellington City.
Wellington Water’s general manager of design and delivery, Tonia Haskell, says the surveys are helping inform selection of the final route for the pipeline.
“We’re examining the condition of the seabed as well as determining whether the undersea Waiwhetu Aquifer extends into both the Lowry Bay and Evans Bay areas that are being investigated for the potential take-off and landing sites for the pipeline.”
The first series of bores have been completed in Evans Bay and the barge is now undertaking a further series in Lowry Bay. It will return to Evans Bay later in November to complete a final series of tests.
“Some of the work is running 24/7 and we’ve taken measures to ensure drilling does not exceed noise limits by fitting the barge with acoustic curtains and ongoing noise monitoring.”
Ms Haskell says the test bores have very little impact on the marine environment. The work involves a thin bore being drilled into the seabed, which is then capped, and the seabed reinstated.
“As part of planning for this project we’ve commissioned marine scientists to carry out extensive assessments to ensure it will have a very minimal and temporary impact on the marine environment and aquatic life, and that any impacts can be mitigated.
“The drilling we’re doing has much lower noise levels than other conventional drilling operations, and we’ve been advised that there is a low risk of any impacts on marine animals from the drilling noise.”
Ms Haskell says the only possible behavioural impacts on marine mammals might happen if they get within 100m of the rig and remain close by for a long time, which is unrealistic given marine mammals are generally transiting the area.
“We're keeping an eye out for whales, and if we see any within 100 metres, we will cease drilling.”
Wellington Water is continuing to work closely with any affected parties and users on both sides of the harbour to ensure everyone understands the project and the work will not clash with any major activities.
“As always, we really value and appreciate the understanding of the local community as we work on this critical project to improve our city’s water resilience.”
The work is being carried out by Griffiths Drilling, the company that carried out the initial exploratory harbour bores during 2017 and 2018 to help determine the best option for an alternative water supply for Wellington City.
Visit www.wellingtonwater.co.nz/CHP to find out more about the project and latest updates.