The Whakatāne District Council’s Policy Committee has received an update on the mitigation of life safety risks from future debris flows for those living in the Awatarariki Stream fanhead area at Matatā.

The report to last week’s Committee meeting detailed progress on a number of the workstreams approved in July 2015, including:

• Confirmation of the risk rationale and location of hazard lines at a property boundary level
• Current property valuations to be assessed, recognising all regulatory restraints and future risks
• An investigation of escape routes, early warning systems and rates relief
• Initial approaches to central Government and the Bay of Plenty Regional Council with regard to funding contributions to a voluntary managed retreat process

Reporting to the Committee, Manager Strategic Projects Jeff Farrell said the review of the hazard and risk modelling had resulted in an increase in the geographical area from which retreat from the debris flow risk has been recommended. “The area includes 16 existing dwellings and 28 vacant sites, of which seven are owned by central government agencies or the Council.”

Mr Farrell also noted that the proposed debris flow risk reduction strategy was founded on voluntary retreat, which meant residents had a choice to remain. “For those who choose to stay in their homes, investigative work has identified a feasible additional escape route through an unformed public road to the west,” he said. “While this would not mitigate the risk from future flood and debris flow events, it would provide an alternative route for anyone needing to move out of the risk area to a safe location.”

The possibility of providing a debris flow early warning system was considered “problematic” in terms of its effectiveness, cost, timeliness (due to the time needed to identify accurate triggering thresholds) and the potential for legal liability, should the system fail . “Investment in a warning system of limited effectiveness also does not align well with the Council’s philosophy of encouraging a retreat from the debris flow hazard,” Mr Farrell said.

The committee adopted recommendations that a project plan and budget be developed to establish the western escape route; but that an early warning system should not be pursued at this time.

Workstream investigations also concluded that the Council’s disaster mitigation and stormwater rating policies have been applied correctly. However, because the application of the Rates Remission Policy was dependent on property owner applications, a high degree of variation between properties was noted. 

Staff will now progress the workstreams relating to the impact of property values on rates and the development of a voluntary managed retreat option.