Residents worried by bank erosion

The Leith River has undermined a section of its bank. Photo by Jonathan Chilton-Towle.
The Leith River has undermined a section of its bank. Photo by Jonathan Chilton-Towle.
The Dunedin City Council is monitoring a section of the Water of Leith's bank that residents were concerned was at risk of collapse.

Last week, a Leith Valley resident contacted the Star with concerns that the river had undermined its banks beside Malvern St.

A section of retaining wall had fallen away creating a small cave in the river bank which the Leith passed through.

The resident was concerned the gap made the bank unstable and might put the public at risk because people often walked or parked cars on the grassy verge above the river.

Otago Regional Council director engineering hazards and science Gavin Palmer said the ORC was aware there had been problems periodically at the location, most notably bank erosion as a result of an April 2006 event.

''The DCC addressed this at the time as the threat was to their infrastructure [public roads] as it may be now. That is a matter that DCC will need to assess in terms of the road reserve and the road itself,'' he said.

''This is outside the extents of the Leith Flood Protection Scheme, however ORC is happy to advise DCC on the solutions available to them to reduce the risk of further erosion of the road reserve.''

Bank erosion was a natural process and the approach that should be taken and the responsibility for acting on that depended on the particular situation, he said.

''We are however reviewing our approach to management of river banks, starting with the Kakanui/Kauru Rivers in North Otago.''

DCC transportation policy engineer Jon Visser said the DCC was aware of the erosion on the banks of the Leith.

''The Leith bed has been continually changing, since even before the Dunedin city area was settled. The DCC has been monitoring this particular location and is prepared to intervene if required.

"The issue is general erosion of the unsupported bank. At this stage, the DCC does not believe the erosion presents a significant risk to the road or road reserve, although that position may change,'' he said.

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