Te Mato Vai

 

Customer: Cook Islands Government 

Location: Rarotonga 

Contract: Design and Construct 

Project Capabilities

Civil Pipelines
  • 10 intake structures
  • 20m diameter storage tanks
  • 25 ford crossings 23 hydraulically driven jacks
  • 12km of 315 OE PE pipe connects the new facilities to existing ones

Delivering fresh water to Rarotonga

This project was a multi-staged upgrade of the water supply network on Rarotonga involving the design and construction for the upgrade of ten existing water intakes at remote sites across the island, construction of 12km of replacement trunk main from the intakes to the new ring main, and minor upgrades to the access roads to eight of the 10 intakes.

The largest infrastructure project ever undertaken in the Cook Islands, Te Mato Vai will deliver fresh drinking water to all residential and commercial properties connected to the existing network on Rarotonga. It improves water storage capacity and also addresses various environmental and health risks associated with the existing water network. It is an important part of the Cook Islands National Sustainable Development Plan. Te Mato Vai will deliver a high standard new water network, improving the quality and capacity of drinking water. 

McConnell Dowell delivered Stage 2, comprising four Separable Portions:

  • SP1: Design of the new water treatment process.
  • SP2: Construction of the 10 new intake structures, as well as sedimentation tanks, sand filters, AVGs, and bolted steel water storage tanks up to 20m in diameter and 8.5m high.
  • SP3: (Build only) installation of 12km of HDPE pipe connecting the new process facilities to the existing network
  • SP4: Commissioning of the plant

Stage 1 of the project involved the construction of a replacement ring main around Rarotonga, which was completed by CCECC in 2016.

The challenge

The intake structures are spread across 10 different work sites, from private land to challenging terrain deep in the mountains (including one at the top of waterfall!), making access difficult. Effective procurement, especially any long lead items was essential for the timely supply of materials to sites that are geographically remote and/or pose considerable logistical challenges.

The solution 

Vigilant planning has enabled us to install the structures safely in the challenging environment and maximise productivity across multiple work fronts. Extensive liaison with landowners has been essential to undertake the works required in private land with minimal disruption.  

Innovation on the island

We developed an alternative method for the construction of the storage tanks, which signifincatly reduced the amount of labour required to build the structure and work at height, greatly improving safety.

Employing local and upskiling for future employment

We engaged a significant number of local people and subcontractors on the project, injecting valuable income into the local economy. We trained a number of local staff as welders, providing them with valuable skills for use in future employment.

McConnell Dowell’s community involvement was well received during our time on the island. A successful family bbq day on the lagoon was attended by a large crowd who also came to support a large scale rubbish collection around the lagoon and airport. Featuring in the local newspapers, over three dump trucks of rubbish was collected and disposed of correctly.

Maximising local procurement for greater social benefit to the local people

Some materials were very specialised and therefore sourced from overseas, however a large portion was procured on island from Cook Island-owned businesses. Plant and machinery hire was often through local companies. Aggregates for trench backfill, foundation slabs and concrete batching was locally quarried. General building and formwork materials were purchased from local merchants. A wide variety of local subcontractors and companies were engaged through the course of the project. This included but not limited to customs clearance, shipping and freight, hiab and crane hire, concrete supply, fencing subcontractors and electricians.

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