The Tauranga water supply network is located on the north east coast of Aotearoa New Zealand. The key focus of this study was to investigate the options and provide a feasibility study that adhered to the Future Ready®, evidence based high-level Environmental Scan of Tauranga and the Western Corridor over the next 30-40 years. The scan was based on global and national future trends relating to climate, society, technology and resources.
This project covered the following physical elements of the water system:
- Location and requirements for major water pumping stations.
- Requirements for storage at strategic locations making use of elevation advantages.
- Conveyance pipelines (pressure and gravity mains).
WSP provided an implementation plan that considered adaptation to various uncertainties, such as demand management, housing densities and growth timings.
CLIENT BRIEF/PROJECT CHALLENGES
TCC engaged WSP to develop a Water Supply Study and Implementation Plan for delivering the optimal solution for water servicing of the Western Corridor. The plan needed to meet the requirements of National Policy Statement on Urban Development Capacity and Freshwater Management. The plan would also be the first step in ultimately developing a clear design basis and masterplan for water infrastructure. This master would include a flexible staging plan to service the various growth areas, based on the assessment of the most relevant and highest priority future implications for Tauranga and the Western Corridor Water Supply.
The Future Ready® resources megatrends identified as high priority(the challenges faced by TCC and the wider community). These included:
- Sustainable Practices (practices that prevent harm to the environment)
- Resilience and reliability (a water system that is safe and will stand the test of time)
- Climate Risk and Hazard Mitigation (practices that protect from the changing climate and its impacts).
OUR SOLUTION
Following completion of the assessment, including a multi-criteria analysis (MCA) assessment, the highest scoring option was taken as the preferred solution.
The benefits to the solution developed by WSP included:
- Strong alignment with Future Ready® Critical Priorities. This included good ’bi-directional flow’ and interconnectivity between east and west, and facilitates transfer across reservoir zones for resilience.
- Scored second on sustainability due to additional carbon emissions from pipeline and reservoir infrastructure construction, and operational energy.
- Ease of staging, adaptability to changes in development staging and use of existing and proposed road corridors as much as possible.
- Simplicity of operation (reduced pump station maintenance) and minimised pressure control systems.
- Adaptability, particularly in Stage 2 of the developments.
OUTCOME/CLIENT BENEFITS
The Western Corridor project aligned Tauranga City Council with their stakeholders in two key areas:
- Resilience to climate change
- building an inclusive, vibrant and sustainable city
LIST OF PRIMARY SERVICES
WSP’s multi-service team managed the project from start to finish. Our water asset technical lead confirmed the design standards for the project with the client. The growth areas and timing of growth areas where checked to determine the water demands and predicted growth models. Our planning and geotechnical team leads identified constraints, including geotechnical, resilience, archaeological to develop a ‘first-cut’ of options, focusing on both gravity and pumped systems.
The second stage saw the project team score and shortlist (through a high-level MCA) three options to take forward.
The short-listed options were put through a detailed assessment and costing and taken to a detailed MCA to identify a preferred option.
The preferred option was then taken through a further ‘what if’ assessment to identify various adaptive pathways for implementing the plan to meet the requirements of the project.
KEY FACTS
As Aotearoa New Zealand’s fifth-largest city, Tauranga is growing rapidly. Its Western Corridor is a key growth area and requires its water supply to meet future demands in a resilient, sustainable and economic way. The project meant WSP:
- Delivered adaptive infrastructure and alternative solutions that applied ‘big picture’ and ‘outside the square’ thinking.
- Incorporated long-term sustainability and resilience of the network to natural hazards.
- Brought together nationally recognised experts and robust decision making, based on reliable evidence.
