Flood protection bund for South New Brighton unlikely
The Christchurch City Council is considering overturning a previous decision to build a flood protection bund in South New Brighton.
The rethink has been prompted by new data which showed the level of flooding risk was significantly lower than originally thought.
The council decided in October last year to build a temporary $600,000 bund from Bridge St to the South New Brighton jetty on the Avon Heathcote Estuary waterfront to protect about 19 homes from flooding risk.
However, a council report, to be discussed at the infrastructure, transport and environment committee tomorrow, said new hydraulic modelling showed a only one home was at risk of flooding above the floor and 70 under the floor during a one in 50-year tidal event.
Staff were now recommending the council defer the bund work and have it considered as part of the South New Brighton Regeneration Strategy.
On February 2 a record high tide of 11.02 metres was recorded at Bridge St and while there was surface water ponding in Seafield Pl, no properties were inundated to ‘‘any significant degree’’ by tidal flooding, the report said. Seafield Pl had been expected to benefit most from the bund.
The road ponding was likely due to the inability of the stormwater network to discharge the volume of water, the report said.
The council had been under pressure to address the flooding risk in the area after residents, businesses and clubs criticised the council’s response to preventing flood waters reaching their properties.
Work to stabilise the emergency bund along the estuary edge in Southshore was still proposed to go ahead and the council also planned to extend the Avon River stopbanks for 185 metres immediately south of Bridge St.
Constructing the bund, which would have lasted 20 years, was narrowly approved in October after it was opposed by councillors Pauline Cotter, Deon Swiggs, Tim Scandrett, Mike Davidson, Sara Templeton and Jimmy Chen.
The councillors believed there were other suburbs that had a greater need for flood protection. At the time, staff promised councillors they would report back to the council if further analysis of the proposed works showed a lower flood risk or higher cost.
The report recommended the money allocated for the bund should be redirected to other work that would reduce the risk of flooding to homes that frequently flood above the floor.
Council coastal ward councillor David East said he understood there were other areas in the city in greater risk, but he was disappointed the bund could be deferred because it gave greater security to those in the area. He did not want to see it considered as part of the regeneration strategy, because that process was taking too long.
South New Brighton Residents’ Association secretary Seamus O’Cromtha said the area needed to be protected from erosion.
He believed the council should be assessing the threat based on a one in 200-year event.