FAQs

In July of 2021, leakage was discovered in our impounded supply. Additionally, our water treatment plant is unable to treat water with an NTU (Nephelometric Turbidity Units) level of above 10. This happens when our river is turbid which occurs after heavy rainfall. Due to the original design of the impounded supply, we are also unable to use the lower 6 metres of water.

The following steps have been taken to improve our situation:

  • Council passed resolutions that included funding of $3.2 million for raw water pre-treatment, $400,000 to purchase a raw water storage tank, and a further $2.5 million for an additional treated water storage tank
  • Geotechnical investigations into the impounded supply
  • Decision to not empty the impounded supply to repair the holes but do underwater assessments and repairs. It was advised that the impounded supply is functioning as it was designed, and the focus has been on building resilience. Peer review was sought, and it was agreed that this was the best approach as opposed to replacement. It was noted that while there are risks, there are no immediate risks and monitoring is continuous.
  • Underwater assessment on depressions and holes in the liner. 3 pinholes have been patched and there are currently no additional holes that we are aware of
  • Testing of turbid water from the Tamaki River to inform the decision on whether a clarifier or membrane plant upgrade is required to treat water with an NTU level above 10

  • Continue monitoring the outflow of the impounded supply
  • 6 monthly underwater drone assessments of the liner and as required
  • Investigation into the construction of an additional reservoir for treated water. A potential plot of land has been identified and our project team are working towards next steps for this
  • Cost analysis of the options of membrane vs clarifier solution for the pre-treatment of raw water have to be finalised before we make any final decisions to approach the market. Following the river testing, design specifications are being drafted on a clarifier solution.
  • A submersible pump is being designed and installed to enable the treatment of the lower 6 metres of water in the impounded supply

Essentially, we need to ensure a continuity of supply to the town. In order for us to do this we need to get in place the appropriate resiliency measures to support this. It was advised that the impounded supply is functioning as it was designed, and the focus has been on building resilience. Peer review was sought, and it was agreed that this was the best approach as opposed to replacement. It was noted that while there are risks, there are no immediate risks and monitoring is continuous. Our main effort is to establish an option that treats directly off the river flow no matter the conditions of the river – see information above under ‘what has been done to remedy this’ and ‘what are the next steps’.

Our teams are monitoring the impounded supply to watch out for any further deterioration. We now have approximately 18 months of daily data to support decision making going forward. We have reduced our physical inspections to three times a week, and as a procedure, if there are any oddities that stand out we increase our monitoring to daily. We also carry out six monthly underwater drone inspections, with extra inspections as required, and should it be needed, we will get in expert advice for technical review. Divers have patched 3 pinholes in the liner. At this stage, no additional holes have been identified. Water leakage of the Impounded Supply is currently the least it has been since monitoring has started.

Yes, the water continues to be safe to drink. Samples are taken every week from different locations across Dannevirke to be tested. Installing raw water pre-treatment will provide greater resilience during extreme weather conditions.

The likelihood of long dry summers is one of the considerations leading to the recommendation not to dewater the Impounded Water Supply as was initially planned. This means that next summer, we can expect to have the stored water in the dam as a contingency backup. Work is also underway to investigate potential underground water sources. We will update the community in the near future about this.

Alternative investigations are still underway, bore sites need to be assessed for their feasibility.

The best way to prepare for any potential water shortages is to have a plan, harvest rainwater and think about water conservation in our daily lives. Council will also be providing regular updates and information on how to conserve water.