Project details
The council draws drinking water for its Kaikohe water supply from two sources. Wairoro Stream meets about 70% of the town’s needs and water from the stream is treated at a plant at Taraire Hills. The remaining 30% is drawn from a bore at Tokareireia (Monument Hill) and treated at a plant on the hill summit.
Water shortages in the town were acute during the 2019/20 summer following record low rainfall in 2019. At the height of this 2019/20 drought Wairoro Stream flows dropped to less than one litre per second at the council water intake and Kaikohe taps were in danger of running dry.
To ensure the town is more resilient to future droughts a second much deeper bore has been drilled at Tokareireia to access greater supplies. This will provide a more reliable secondary water supply to Kaikohe’s main source, the Wairoro Stream.
Drilling of the new (second) bore into a deeper aquifer below the existing Monument Hill water supply bores, began in December 2020 and, after some construction complications, was completed on 24 February 2021.
The new 120-metre bore accesses more sustainable groundwater and can supply about 350 cubic metres of water a day, but will only be used if the Wairoro Stream is running low. 350 cubic metres a day is similar to the current bore’s sustainable (long term safe) yield.
The new bore’s impact on nearby springs and other surface water resources and its response during dry periods was tested by looking at two scenarios:
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using the deep bore exclusively over summer, then using the existing bore in winter to allow the deep aquifer to recover
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or using a combination of the existing bore and the deep bore and allow them to recover in winter.
The new production bore is made of 200mm carbon steel casing to 99m, it also has a telescopic stainless steel screen assembly to 121m.
The project will continue with the consent of the Waikotihe Trust and is scheduled for completion in 2022.
Project costs
This project has an approved budget of $1.18 million.
Project milestones
Stage 1 - Bore design and quality testing
Drilling of the new (second) bore, began in December 2020 and was completed on 24 February 2021. This bore accesses more sustainable groundwater and can supply about 350 cubic metres of water a day.
Stage 2 - Sustainable yield assessment and consenting
To provide a sustainable supply of highly secure potable water for the Kaikohe community, testing of the bore confirmed flows and investigated impacts on surrounding groundwater sources. Testing started on 4 March 2021, continued for 5 days, and was then analysed.
Testing included: 1) a step test 2) a constant discharge test 3) recovery monitoring after the pumping.
Stage 2 was completed in October 2021.
Stage 3 – Reticulation and electrical design
Northland Regional Council granted consent for the project in March 2022 and construction began in May. This included extra monitoring conditions agreed to with the Waikotihe Trust. Iwi approval has been gained for the project delivery.
Physical works have included installing a pump, laying a trenched pipe to connect the bore to the Monument Hill Water Treatment Plant, connecting electricity and fibre, as well as creating an access road.
Most of the construction work was completed by 30 June. Air valve installation, bore headworks and pipework were completed in July. Water pressure testing on the main water line for the new bore was completed in September with bore headworks and upgrades to the water treatment plant also launched. Electricity supply upgrades to the treatment plant are due to start late October, with commissioning of the bore and final treatment testing planned for November 2022.
Gallery
Works completed in October 2022.
New access road completed.
Project documents
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