Flood management subcommittee endorses audit

The Hutt Valley Flood Management Sub-committee has unanimously endorsed undertaking an independent audit of the hydrology, hydraulic modelling and the application of freeboard in the Pinehaven catchment flood maps.

 The decision responds to concerns raised by some in the Pinehaven community that the scope of previous investigations and peer reviews of GWRC's modelling - each of which found it fit for purpose - was not extensive enough.

As a result, the committee:

• required the auditor to review and assess discrepancies between the regional council's flood maps and cases studies presented by the Save Our Hills Group

• requested guidance in the audit on how to set baseline provisions for stormwater neutrality*

• requested guidance in the audit on how to define the impact on stormwater neutrality of intensification of development and how those might be provided for in the Floodplain Management Plan and in District Plan provisions

• deferred further consideration of submissions on, and implementation of, the flood plain management plan until the report of the independent audit has been reviewed and actioned as necessary.

"This is a sensible outcome that walks the line between the regional council leading the flood management process and it also acknowledging the importance of community input into decision making," says HVFMS chair and regional councillor Prue Lamason.

"We've listened to the concerns expressed by some in the community and changed the terms of reference to accommodate their requests. The important thing from now on will be to abide by the findings of the audit, around which we should build a consensus view on the design of flood protection plans."

Regional Councillor Paul Swain, who also sits on the committee, says "we got a very clear message from the members of the community. While they wanted to be sure the information was accurate, they were also acutely aware of the flood risk and wanted the councils to get on with the flood improvement work set out in the floodplain management plan. We are happy to further delay planning and design work ahead of the audit, but every delay increases the risk to the community."

Greater Wellington Regional Council has issued a request for proposal from suitably qualified independent auditors. It expects the audit to be complete before 1 May 2015.

For more information please go to: http://www.gw.govt.nz/Pinehaven/ or media phone on 021 914 266. 

*         Stormwater neutrality means that runoff from the site during one or more specific rainfall events must be managed so that the post-development peak flows are not to exceed the pre-development flows for specific design events.