Monday, 14 July 2014

Flood defence house-tanking pilot successful

Christchurch City Council has successfully concluded the pilot test of the 'house-tanking' flood defence measure outlined in the Mayoral Flood Taskforce report.

The pilot exercise started on Thursday 10 July 2014 using a suitable red-zone house. The 'house-tanking' process involved the application of a waterproof membrane to the exterior of the house and then placing bunding around the house to contain the water. This bunded area was then flooded to a level of 1100 millimetres on Friday afternoon and remained in a flooded state until this afternoon, Monday 14 July 2014.

John Mackie, Unit Manager Transport and Greenspace says, "It is really heartening to see that this technology has been successful. A very small amount of water made its way under the house, which was pumped away by a small submersible pump beneath the floor, but no water came inside or anywhere near breaching the floor levels.

"In the flood-events of March and April this year, some houses experienced these type of flood conditions for up to 12 hours, so it has been a valuable exercise for us to run this pilot over a 72 hour period. That gives us great confidence in this technology in terms of it being a viable flood-defence tool.

"House-tanking is one of the recommendations from the Mayoral Flood Taskforce report that needed to be tested. We now know that this is a flood-defence measure that works.

"The next step for us now is to produce a full technical report of the findings from this pilot test and include it in the final Mayoral Flood Taskforce report which will go to Council early next month. The Council will then decide on which recommendations from the Taskforce that will protect those residents in the areas identified as vulnerable to flooding," Mr Mackie says.

Christchurch City Mayor, Lianne Dalziel established the Mayoral Flood Taskforce as a result of the heavy rainfall events in March and April of this year, which caused flooding across the city. The Taskforce was asked to come up with short-term flood mitigation recommendations for the most flood vulnerable areas of Christchurch.

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