Residents call for action over dangerous, flood prone stormwater basin

A new stormwater basin in a highly sought-after subdivision in the Selwyn district is contributing to flooding rather than fixing it, residents say.

Barton Fields residents are also concerned the basin itself, at almost 3m deep with no fencing or lighting, presents a drowning risk to passersby, particularly at night.

In response, Selwyn District Council is reviewing the basin to ensure it meets requirements but, in terms of flooding, it says so far the basin appears to be "performing as expected".

Barton Fields developer spokesperson Colin Pywell, of Faulks Investments Ltd, told residents on Facebook after a flooding event in September that it would not happen again as a filter cloth had now been removed.

Pywell did not return calls from the Selwyn Times.

Barton Fields resident Sarah O’Brien outlined the concerns of herself and fellow residents in a letter to the developer’s lawyers and the district council last week.

They are calling for the developer and district council to remedy the design and ensure its safety, and that they will be liable for any associated property damage or accidents.

The dry stormwater storage grass basin was installed this year for taking runoff from a new stage of the subdivision, currently under construction.

In the heavy rain event of July, water flooded out onto the subdivision streets of Carnaveron Drive and Faulks Drive, from the conduit that the basin drained into, stranding some people in their homes.

Flooding occurred again on the two streets in heavy rain in September.

O’Brien, who has lived at Barton Fields for three years, was frustrated to see stormwater being diverted to that area of the subdivision and causing flooding.

“The system is poorly designed and not considerate of the dangers and problems it poses to the neighbouring properties, local residents and the already overloaded drainage systems.”

While the developer had since installed a wider pipe and removed the filter cloth, she doubted this would resolve the issue, claiming the wider stormwater system was already at capacity.

In terms of safety, O’Brien said the basin was too deep and had steep sides.

Additionally, its edges become soft when it is full, making it easy to slip and sink into.

It not only needed redesigning but also new fencing and lighting.

A district council water team spokesperson said it had discussed residents' concerns with O’Brien, and the council is currently reviewing the basin to ensure it meets legal requirements.

“The council is reviewing how the drainage network in the area responded in the July heavy rain events but, at this stage, the evidence shows this basin performed as expected,” the spokesperson added.