Flood-proofing, resiting: one or both?

Press, 23 September 1988, Page 13

Flood-proofing, resiting: one or both?

NEIL CLARKSON concludes his two-part series on the disastrous Greymouth flood of September 13 and its aftermath. Photographs by JOHN COSGROVE.

CONTAINING the ' Grey River is not a pipe dream in the eyes of the Westland Catchment Board, in spite of damaging Greymouth floods dating back more than a century. The board’s manager, Warwick Coombridge, says Greymouth can expect river levels akin to the May flood every 18 to 20 years. A flood like last week’s is likely every 53 years. The board believes its $3.3M flood protection scheme will provide Greymouth with many of the answers. Mr Coombridge says the completed scheme would have contained the September 13 flood. “We have checked out the flood levels and believe that the scheme, if it had been completed, would have had a zero impact in terms of property. “It has been reported that some people felt the scheme wouldn't have held it. The scheme would have contained this flood. There is no doubt about that.” He points to the success of the

Cobden wall, which is part of the scheme. "Cobden must be the most cost-effective stop bank in New Zealand. It has twice saved those houses.” The Grey River was 80cm from the top of the protection work at the flood’s height. “We are approaching the Government to make funds available for fast-tracking the completion of the scheme. “We are looking at endeavouring to complete it by the end of 1989.” The scheme involves building a. flood protection wall along Mawhera Quay with a face of huge boulders to prevent scouring by the fast-flowing flood waters. The wall will then swing south, circling the tidal lake and lagoon to protect Blaketown.

Mr Coombridge sees the wall along Mawhera Quay having top priority. Once finished, the commercial area will be protected from the turbulent silt-laden water which overflows the wharf in a serious flood. Water, however, could still enter the town from behind if the lake and lagoon overflowed. “But it will be much lower than if it gets over the wharf.” Completing the flood-protec-tion walls round the tidal areas is aimed at blocking this threat and protecting Blaketown. Government support in pressing ahead with the flood protection work appears essential. The Westland Catchment Board already faces a SI.3M bill in repairing damage to flood protection work along rivers caused in the May flood. September 13

saw another SIM in damage. Mr Coombridge admits the board can offer no guarantees about the effectiveness of the Greymouth Borough Flood Protection Scheme: “You can’t absolutely guarantee that you will never get floods that beat what you put up.” He accepts that relocation of the downtown area may be a medium to long-term solution. “But we take the position that the flood-wall is cost effective and that it will offer the opportunity to rationally plan the flood-proofing of the town. “Any solution has to be a combination of relocation, floodproofing and flood walls.” Mr Coombridge rejects the suggestion that dredging the Grey River will help. In flood the river carries a vast amount of

rock and shingle. It could undo in minutes what a dredge could take weeks to achieve. The Mayor, Dr Barry Dallas, says Greymouth is a regrettable victim of historic circumstances. In 1862 the Canterbury Provincial Council drew a plan for the proposed Greymouth’ settlement south of Sawyer Creek, about I.skm from the Grey River. “Immediately gold was discovered and a boat came in from Collingwood via Westport and anchored on the Grey River bank. They put up a store where they anchored. “The pragmatic town plan therefore developed along the river.” Two hundred acres of largely tidal land south of the Grey River was then given by the Government to the South Island Maori tribe, Ngai Tahu, for fishing use. The same was done with other major West Coast rivers. Dr Dallas says $BOO,OOO to SIM is paid by leaseholders to the Ngai Tahu each year. “The Ngai Tahu will not give us one cent towards the flood protection work.” He says he was dismayed to learn the tribe was proceeding with an application to increase the land rental.

“If they do this we will then have the land revalued. The land is worth very little as of last Tuesday. Two major floods in five months doesn’t make it desirable leasehold land.” Dr Dallas says the flood probably caused SISM worth of damage, but is likely to cost the town up to S3OM once lost profits are added. He talks of his personal reservations about the proposed flood-protection work. “If we go to that expense we have got to maintain quite a commercial presence in the present flood area.” He believes many retailers no longer see the present business district as satisfactory. Some, he believes, will be keen to move. “We will not be persuading anybody one way or the other but we will do everything in our power to help those who have made up their mind to move. “It’s a new bail-game now. It is not a panic move. It is to be a well thought out, well-researched project.” An area being looked at is round Upper Tainui and High Streets. Dr Dallas says investors from Canterbury have already shown interest in relocation suggestions. One, he says, has offered SBM. “I believe that it will be in everybody’s interests that banks, hotels, office-users and the like ’ stay there with the proviso that

they make the first floor of their building parking space.” Dr Dallas says those who built to the council’s minimum floor height imposed a couple of years ago had more than one metre of water through their premises. “I would be happy to impose a 10-foot restriction on occupied space. I wouldn’t be happy with anything else. “Anything that really needs foot traffic will quite honestly have to relocate.” What of the Greymouth, Borough Flood Protection Scheme? “A realistic possible date of completion is one year away. “We have had two floods in

five months. A year does not look good to me. I don’t believe the next flood is a year away.” Greymouth residents and business owners are all too familiar with the risk of further flooding. Many look to Cobden, unscathed in two disastrous floods. Can the same protection be afforded to businesses and homes south of the river? In the coming months the West Coast authorities will make decisions affecting the future livelihood of downtown storekeepers and the security of dozens of home-owners.

Flooding has been a regrettable and heart-breaking part of the life of Mrs Irene Jamieson

during her 70 years in a wooden Preston Road bungalow. Now, at 94, she moves on, escaping the worry and tragedy of future flooding.

For others like Kim Terry, aged 30, and his wife, Carol, aged 27, the worry remains. The couple are uncertain what they will do.

The retired Mrs Pearl Turner is also unclear after water entered her home a second time in five months.

Their future depends on whether local authorities can make low-lying areas of Greymouth safe from the turbulent, fast-flowing floodwaters of the Grey River.