Thames Valley diversion channel planting and maintenance programme

FAQs

• Is there a current risk to the Piako River scheme?

  The maintenance of stopbank height will ensure flood protection continues to be provided to the agreed level of service of a 1% annual exceedance probability tidal event. Planned stopbank relocation will address the risk of stopbank instability due to river widening reducing berm width in places along the river.
• Why are you relocating some sections of stopbank?

  When the Piako River Scheme was constructed, the stopbank infrastructure was set back 15 metres from the river to create a riverside berm and maintain stopbank stability. This riverside berm has locally degraded over time, having widths as little five metres and resulting in increased risk of instability. We will be relocating sections of stopbank identified as having a higher instability risk due to a riverside berm width of less than 10 metres.
• Where will the berms be raised and by how much?

  We will raise the berm over the entire stopbank length to restrict mean high water spring tidal inundation, piping and river widening to help avoid any future stopbank shifts. We will raise the berm by up to 500mm along its entire length, reusing sediment captured from the Piako River.
• How much earthfill is required to raise the berm?

  For the enabling and construction works for the right bank stopbank upgrade, it is estimated that a volume of 176,000 cubic metres loose measure is required. The quantity of total earthworks (including the left bank stopbank upgrade) is estimated at 212,000 cubic metres loose measure.
• Why do you need to purchase land for this project?

  Most of the working area is Waikato Regional Council owned land for the flood scheme. However, we need to purchase land from adjacent private landowners where our work will extend beyond current boundaries, for example, where we need to shift sections of stopbank inland. We have negotiated with the five affected landowners to obtain rights to occupy and undertake the land purchase process.
• What permissions are required for this project?

  The proposed upgrade works are either permitted activity under the Regional Plan (provided no imported fill is required for the berm upgrade works) or are covered by an existing consent. We will be using sediment already recovered from the river and a local canal as material for the earthworks, for example, for raising the height of the stopbank.

  A district council designation change will be sought to encompass planned land purchase.  This will ensure the land is covered by the protections afforded by the Soil Conservation and Rivers Control Act.
• What does this mean for me as a ratepayer?

  The upgrade to the stopbank is planned regular renewal works, however, this work would normally have been fully paid for by the ratepayer so the co-funding relieves the financial obligation on ratepayers and allows upgrade work to be completed sooner.
• I have a land licence agreement to graze this area. What does this mean for me?

  There will be no grazing within the project area during the enabling and construction works.

   All cross-boundary fences over the stopbank within lease areas and around the drains leading to the floodgates will be removed for the enabling works to happen.

  Grazing will be permitted after these works have been completed but must cease ahead of the planned stopbank construction works starting in October.

  For this interim stage, Waikato Regional Council will reinstate temporary fencing at the boundaries of licence area, however, the setting up of temporary fencing inside the licence area will be the responsibility of the licensees.

  Some troughs will remain in place. Any changes to water supplies will be communicated directly with affected licensees.

  Grazing will not be possible for a year after the construction period while the grass reestablishes.

  In less affected areas, licences may be reviewed depending on grass cover.
• Does this project have any implications regarding the outcomes of Hauraki Plains Adaptation Plan?

  No, as we are not making any changes to the level of service of the flood scheme, this project will not affect the outcome of the community-led project led by Hauraki District Council and Waikato Regional Council to prepare the low-lying Hauraki Plains for climate change impacts like increased flooding and sea-level rise.