The Government was more successful in its venture into opencast mining. Small-scale open-cast mining had been undertaken before the war, but large-scale operations were a direct result of the wartime coal shortage.
The first new area to be opened up was Glen Afton, where work commenced in October 1943 and the scheme came into production in January 1944. In its 1946 annual report, the Mines Department said:2page 413
‘Since 1943 the Mines Department has paid increasing attention to this form of mining. For a commencement extensive geological and topographical surveys, followed by drilling, were required to locate suitable areas, define depths of overburden, and facilitate layout of stripping operations. Shortage of earth-moving equipment was a severe handicap at the outset, but in 1945 the Mines Department was able to import two 5 cubic-yard Bucyrus Erie electric drag line shovels, and since then production has considerably increased.
‘Generally it has not been until 1945 that the full effect of the Government's open-cast policy has been felt. In 1945 there were fifty-one open-cast mines in active operation, which produced 452,680 tons of coal, a little over one seventh of the total coal production. Production by open-cast mines has increased progressively from 55,774 tons in 1942 to 62,037 tons in 1943, to 196,454 tons in 1944, to the record figure of 452,680 tons in 1945. The greatest proportion of this increase has been due to the eight open-cast mines operated by the State, none of which were in existence in 1942, but which contributed 257,467 tons of the 1945 total.’
Chart 70 shows changes in output of coal.page 414
In the later war years the acceleration in open-cast mining considerably boosted coal production in New Zealand. In 1939 only 2 per cent of New Zealand production came from open-cast mines, but by the end of the war their output was approaching one-fifth of all coal production.
Open-cast mining had another important influence on efficiency in mining. It was only the extension of this method which avoided a substantial fall over the war years in the output per man for the whole industry. After 1943, the rapidly increasing proportion of production obtained from open-casts, where relatively high per-man outputs could be obtained, should have materially increased overall efficiency in production. Unfortunately the increase in tons per man for the whole industry was small. The gain in open-casts was offset in the later war years by a steady decline in the rate of output of miners working underground. Commenting on this, and on the related fall in bituminous coal output, the Mines Department says in its 1946 report:1
‘It will be noted that in the case of underground mines, while the output per man increased during the years 1941 and 1942, there has been a progressive decline since then. This is due in great part to conditions brought about by the war. Increased production has been expedient in those years even if future production was thereby affected, and the effect has been cumulative with the years. Restriction of essential development work in the interests of immediate production, the shortage of skilled miners, and the increased average age of the coal-hewers owing to the difficulties in replacements with younger men have all contributed to lessen the output-per-man figure.’
Referring specifically to bituminous coal, which came from underground mines, the 1947 report says:2
‘… New Zealand's resources of bituminous coal are not unlimited, and after many years of exploitation the more accessible and easily worked deposits are approaching exhaustion, while, owing to the lenticular nature of the deposits, extensive boring is necessary before development of new mines can be undertaken with confidence. It was inevitable during the war years with shortage of manpower that essential development work had to be sacrificed to the exigencies of the time, and there is accordingly considerable leeway to be made up.’
The output of bituminous coal fell steadily after 1941 and by 1945 had dropped 22 per cent.
In spite of these difficulties, the wartime performances of the page 415 coal-mining industry, considering the degree of protection given against losses of manpower to the forces, the concessions made to the workers by the Government, the transfers to state ownership to keep mines operating, and the very extensive Government development work in open-cast mines, can only be regarded as disappointing.
2 Parliamentary Paper C–2, Mines Statement, 1946, p. 6.
1 Parliamentary Paper C–2, p. 5.
2 Parliamentary Paper C–2, p. 6.