Dredge tailings reclamation ‘still on trial’

Press, 30 April 1982, Page 19

Dredge tailings reclamation ‘still on trial’

G.reymouth reporter

.. The resoiling and sowing of bld dredge tailings on the Taramakau River was still in the category of trials and had been an experiment unique in New Zealand, about 60 West Coast farmers were told at a field day on the Taramakau River last week.

The field day was arranged by the Ministry of Agriculture and Fisheries to show farmers what the Kanieri Gold Dredging Company had done in restoration experiments on dredge tailings. While the company had not been required to do restoration in its early days, it had held the trials to help it in preparing its plans for the Grey Valley, where a new dredge is being built at Ngahere, the farmers were told.

On the Grey River, the company, as part of its conditions of licence, is required to restore fully the land to pasture — including sections which are at present riverbed — and to make stopbanks for river control. Farmers, in general, have opposed the dredge’s introduction into the Grey Valley, and some of those affected were present on the field day. They heard also from a Taramakau farmer, Mr Passmore Stewart, who has fought the dredging company through the courts unsuccessfully, and who, after-walking with others over the trial blocks of cultivation, said it was a failure. The company, he said, had destroyed the soil so that it did not need to restore it.

He was supported to some extent by a spokesman for the mining committee of West Coast Federated Farmers, Mr John Ritchie, who likened the company’s attempts to that of a baby taking its first steps. Mr Ritchie said that, after dredging, the farmers had no option as to the type of soil that they were left with. This comment was backed by an Ikamatua farmer, Mr P. Kennedy. However, the dredging company’s agricultural consultant, Mr R. D. (Ron) Keating said that dredged land could be restored to the state it was in before the dredging. He gave as an example agricultural land in Great Britain which was back to normal, four years after it had been moved for opencast coalmining. The farmers were told that in the early days of dredging

restoration had not been required. Five years ago the Westland Land Use Commit.tee had been asked to look at ways of using dredge tailings.

The committee, according to its convener, Mr Murray Ellis, of the Department of Lands and Survey, decided that the best use was for forestry, as there was no real agricultural base in the Taramakau area.

Pointing to ah area of grassed tailings on which sheep were grazing. Mr Ellis said that it had been designated — although not yet gazetted — for trees. His comments preceded a remark by a prominent West Coast farmer and Grey county Mr A. S. G. (Athol) McGeady, that he considered it had been shown that the • area could be farmed. Mr Ellis said his committee wanted to ensure that the conditions imposed on the dredging company in its new licences in the Grey Valley were carried out. The company, with its trials on the Taramakau, was showing what it was trying to do.

The party — which was co-ordinated by Mr Peter Brierley of the Ministry ol Agriculture and Fisheries at Greymouth — was shown over a total of 65.6 hectares of tailings at various stages ■of development.

The first block of 12.8 ha was contoured by the company in August 1979, covered with silt and sand and some gravel to a depth of between 150 mm and 200 mm, and topdressed with 2.5 tonnes of lime and 600 kg of superphosphate per hectare, before being seeded at the rate oi 15kg per ha. The second block, of 11.3 ha, was contoured in October, 1980, and some silt and sand from an old stockpile was spread over part of the block and sown the same month. It was. top-dressed last September and first grazed on a rotational basis two months later.

The third block of 41.45 ha, including a lOha freehold block which reverts to Mr Stewart, was contoured. The freehold section was covered with, silt and sand to a depth of between 150 mm and 200 mm, and the block sown last month.

The experiments had shown that an area sown 18 months ago could now carry 17 stock units per hectare, which was "not bad,” said Mr Keating.