Shingle from the seabed

Press, Volume CXIV, Issue 33669, 19 October 1974, Page 9

Shingle from the seabed

(By

DENIS WEDERELL)

The sea may yield more' than gas, off the New Zealand coast. Before the end of this century i it may become a major source of shingle for the building industry and for roadmaking. In Northland, where little high quality rock can be had and where the rivers are silty, a company called Landsea Minerals, Ltd, has applied for a prospecting, right with the intention of dredging the seabed at six points, all of them close to the east coast. In Nelson, the rate of extraction from the Motueka River is worrying the Nelson Catchment Board; the demands being made on river- . beds close to Christchurch may already be too high, . and the flow of shingle com- ’ ing down the Waitaki River has been so diminished by • the dams for hydro-elec-., tricity that its deposits are ' not being renewed. Only the Rangitata River,:' ranging widely over itsL South Canterbury bed, seems , to offer long-term prospects. | The shortage Of shingle in Northland is accentuated by the growth of Auckland. Auckland’s own volcanic cones are fast being worked' out, the cost of land for quarrying is becoming prohibitively high, and the city’s demands on the region are increasing rapidly. Northland’s roads have never been good, and haulage costs are high. Offshore dredging offers a substantial resource of shingle: up to 1000 years at the present rate of use. Landed costs may be as little as 25 per cent of the present prices at quarries. Landsea Minerals is proposing nothing new. The inshore seabed of the North Sea is being extensively dredged by most of the nations bordering it; some preliminary work by Australia in the 1960 s indicated vast reserves below the oceans; and the UnitedStates is also surveying its; continental shelf to deter-; mine the extent of deposits.' Britain obtains about 10 per cent of its sand and gravel’ by marine dredging. Mr J. A. Bretherton, S.M.J in the Whangarei Court,' heard the application by 1 Landsea Minerals, Ltd, for a prospecting licence. He, noted that the company had said in its supporting evi-l dence that it was interested! in six areas, from Awarua! Rock (just north of Bream Head, at the entrance to Whangarei) to Stephenson Island (north of the Bay of Islands). “The total of these six seabed areas is about 22,000 acres,” said Mr Bretherton. “The applicant says that the

[ Northland market for gravel (and sand is about 300,000 ! yards a year, and estimates that these six areas would be enough for 1000 years. The inspector of mines i and quarries made no objection to the granting of a prospecting licence, the Northland Catchment Commission and the Northland Harbour Board made no objection. But nine private people, mostly residents of Pataua, a recreation area for Whangarei, objected on environmental grounds. They were concerned about seashore erosion, interference with marine life and recreation, and property devaluation. They complained that commercial exploitation of the coast and of marine recreational areas should cease. The Magistrate’s report to the Minister of Mines covered other possible objections, not referred to in evidence, and recommended against the granting of a prospecting 1 licence. But Landsea Minerals, whose parent company is Busck Concrete, Ltd, of I Whangarei, told the Court (that it proposed to commission an independent environmental impact report before the granting of a mining licence. It brought expert evidence to show that there would be no coastal erosion, and that the shingle deposits were marine deserts, almost devoid of marine flora and fauna. The Ministry of Works water and soil division, which is making a national survey of shingle and sand resources, and is becoming concerned about the increased demand on land, wants to see Landsea Minerals succeed. The Commission on the Environment appears t<j be satisfied with

the provisions made for impact reporting, and the Mines Department has no objections as matters now stand. The Ministry, of Transport (Marine Division) and the Ministry of Agrculture and Fisheries may both, through their Ministers, impose conditions on the granting of a mining licence, although they

cannot block the issue of that licence once a prospecting licence has been granted. It is probable that, before the Minister of Mines decides on the company’s application, the Ministry of Agriculture and Fisheries will have an opportunity to make its own survey of the offshore deposits.

Even in Canterbury, where all a contractor need do to obtain shingle is to buy a paddock and dig a pit, the Ministry of Works is concerned about the rising demands from builddrs and road contractors.

“While it’s easy enough to get shingle out of a paddock, that takes land out of production, and we’re not in favour of that,” said a spokesman for the Ministry. “Where pits are dug, some thought must be given to the future use of that land.”