A report on the options for managing debris flow hazard affecting properties in Matatā’s Awatararariki Stream fanhead was received by the Whakatāne District Council’s Policy Committee on Wednesday, 11 December. The report sets out the findings of a draft risk assessment by engineering consultant Tonkin and Taylor Ltd and proposes three possible approaches to managing the risk debris flows pose. 

The Council agreed to receive the reports to enable consultation with all affected landowners to be undertaken early in the New Year. Affected owners will be offered one-on-one briefings as part of a consultation process designed to let the Council know how the community wishes to proceed.

“Our earlier work relating to the Awatarariki Stream indicated that it is not economically or practically feasible to mitigate (reduce) the known debris flow hazard from the catchment through an engineering solution,” says David Bewley, the Council’s General Manager Strategy and Planning. 

“New Zealand currently relies on international standards for determining acceptable levels of natural hazard risk. The site-specific study for the Awatarariki Stream fanhead area shows that, for an event on a similar scale to the 2005 debris flow, those living on the most at-risk properties would face a loss-of-life risk that is higher than would be considered acceptable in many parts of the world. As debris flow risks are very difficult to reduce, this is likely to result in restrictions on future development in that area.”

Possible options identified for managing the area include:

• Maintaining the fanhead area much as it is, leaving property owners (including the Council) to initiate any clean-up activities, and amending the current rating policy to allow rates on undeveloped land to be remitted
• Restoring the area by removing rocks and other debris and grassing the area to improve the amenity value of the affected land
• Restoring and retreating from the most at-risk areas, including a long-term plan to purchase undevelopable, hazard-prone land as a public recreation space

All options include a package of other methods that include hazard zoning under the Whakatāne District Plan, the introduction of catchment monitoring, and further investigation of hazard warnings and evacuation protocols.

The report also recommends that Mayor Tony Bonne seeks Central Government assistance with risk reduction measures.

Mr Bewley says letters will be sent to all affected property owners early next week to update them on developments and arrange for one-on-one consultation meetings early in 2014.