Starting with an investigation of infrastructure condition through to water supply design and modelling, and near full replacement in one of the North Island’s most treasured regional parks.

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A Significant Location

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Tāwharanui Regional Park sits over an hour north of Tāmaki Makaurau/ Auckland City at the end of the Tāwharanui Peninsula. This remote bird sanctuary includes some of Aotearoa’s rarest birds and marine life and is one of the most popular destinations in the Auckland region for camping, receiving estimates of over 150,000 visitors per year.

The Tāwharanui Peninsula have been occupied by several iwi and hapū providing an interweb of semi-continuous occupation and adding cultural and archaeological significance to the peninsula. European land sales passed to a Portuguese family in the 1870s, whereby the land was cleared of bush and utilised for sheep farming. Some of this land has since been rewilded at the end of the peninsula, becoming what we now call Tāwharanui Regional Park.

Existing sanctuary protections and the importance of biodiversity and habitat protection in the area meant a wide arc of stakeholder engagement, with environmental and archaeological considerations at the forefront of the design, to meet the on-site water infrastructure needs of large visitor populations.

With the growing visitor numbers and aging infrastructure meant increased water loss and maintenance costs resulted at the site. From this, a decision was made to develop a solution.

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The Infrastructure Investigation

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The project to investigate the condition of water infrastructure across the regional park began with a hui involving multiple stakeholder groups with interest in the construction project and improving the condition of water infrastructure.

Auckland Council departments, representatives from Ngāti Manuhiri, maintenance contractors, and on-site rangers all engaged to lend their thoughts and knowledge of the system and the land to Morphum’s investigation.

What began as a few lines marked on a laminated map soon transitioned into an engineering design where the specifics of how the system would operate were developed.

Morphum continually engaged with mana whenua, archaeologists and council departments to get valuable operational input on design elements, and specification preferences which would become part of the system.

The Morphum science team was called into to delineate a wetland near the abstraction bore, to ensure minimal impact on habitat and the native bird reserve in the area, which includes a population of endangered Takahē and Brown Kiwi.

Improvements to select prioritised areas were targeted across the system, with the initial plan being to replace a 1.5 km long critical main between the water abstraction bore and storage tanks that gravity supply potable water to the park. The scope of the replacement grew into a near full replacement of potable and non-potable water infrastructure as more opportunities were identified, all of which was completed within a short construction window.

Once the tracing of each line in the system, modelling and calculations of project upgrades was completed, fitting in with tight timelines, a revised scope was agreed upon. This scope was endorsed through a kaitiaki report by mana whenua and met the requirements of the Archaeological Authority approved by the Heritage New Zealand.

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The New System

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To improve the system operation and reduce maintenance costs, it was decided that approximately 75% of potable water infrastructure and 100% of the non-potable water reticulation would be replaced. The Morphum Engineers then assisted in overseeing construction in close liaison with Auckland Council Parks & Community Facilities. Morphum’s team assisted in project and contract management to track construction and documentation throughout the course of the construction and provide direction to both Auckland Council and the Contractor.

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The water reticulation improvements at Tāwharanui Regional Park included:

• 25km of new water pipes, with above-ground infrastructure to minimise environmental & archaeological impacts and reduce cost of installation and maintenance.

• Three new pumps to supply water across the park,

• 200 new valves – isolation valves, air valves, non-return valves and others.

• Nine new water storage tanks.

• A new generator incorporated into dual pump system, with a solar pump and generator-powered electric pump for backup supply.

• Strategic improvements to power and water supply locations to allow for future improvements.

• Pre-treatment improvements to non-potable water supply.

• 30 new water troughs with allowances for native flightless birds to escape.

• Power, componentry and site operational improvements across the park.

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Thanks to the efforts of those involved, the project has been completed, and water is actively being supplied across Tāwharanui Regional Park with minimal impact and overwhelmingly positive feedback.

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