Water-races for early goldmining

Press, Volume CXI, Issue 32703, 4 September 1971, Page 11

Water-races for early goldmining

The Immigration and Public Works Act of 1870, which provided for the establishment of the Public Works Department, included as one of its tasks the building of water-races to provide adequate supplies for goldfields.

At that time, before the development of refrigeration to facilitate the export of meat, the promotion of mining was important, the export of gold providing a major source of overseas funds. Races were constructed near Thames, in Central Otago, and on the West Coast This article deals with races in the latter area only. Hydraulic sluicing, one of the important methods used in mining, involves playing powerful jets of water on to erodible faces of shingle and sand, the resulting sludge being washed down into races whose floors are covered with coir matting in which the heavy particles of gold are trapped. This calls for large quantities of water under high pressure and the smaller groups of miners were not in a position to undertake the heavy engineering works necessary to provide such water. On the West Coast proposals for the Nelson Creek, Waimea and Mikonui Races had been prepared by 1872. Nelson Creek Nelson Creek joins the Grey River some 12 miles above Greymouth.’ It receives the outflow from Lake Hochstetter and the race was designed to bring this water

to serve the goldfield between Callaghan’s and Nelson Creeks. A race is essentially a trench located on a fairly flat grade and large enough to carry the required quantity of water. This one was over 16 miles long and large enough to deliver 60 cusecs, or 32,400,000 gallons a day. It involved exceptionally heavy work including more than 10 miles of ditching, six miles and a half of tunnelling lined with timber, and one mile and a half of channel constructed of timber, known as fluming. This fluming included five bridges, varying in span from 100 to 150 feet, and standing from 70 to 170 feet above the levels of the creeks which they crossed. Waimea The Waimea race had its intake in the headwaters of the Kawhaka Creek, a tributary joining the Arahura River 4j miles from its mouth. It served the country around Stafford. Later an extension was constructed to serve the Kuntara goldfields. The initial race, 16 miles long, was designed to deliver 40 cusecs. The extension, having three-quarters of this capacity, required another five' miles of race. Heavy construction was involved at the headworks and cast iron pipes were required for part of the main race. Work commenced in 1874 and the extension was completed in 1879, the total cost being £141,000. To illustrate the economic value of races, in his 1879 annual report the district engineer stated that during

the year 617 men had been employed in the area served by the race and 2L400 ounces of gold had been; won by them. Mikonui The history of the Mikonui race is a tragedy. Intended to supply the Ross goldfield, it was to be some 15 miles long and to draw water from the headwaters of the Mikonui River. A tunnel nearly two miles long was to extend from the Totara to the Donnelly’s Creek watershed. Due to local apathy and later to the high level of tenders received construction did not start until 1879. By March, 1881, work was completed in the Donnelly’s Creek section, including tunnels aggregating lj miles. By December, 1883, two contracts covering about half of the long tunnel had been let. The rock encountered, although solid, swelled when exposed to the air and required heavy timbering. In August, 1885, the contract at the Ross end was completed, but at the other, end after completing 21 j chains the contractor abandoned the job. With a deepening depression no further contracts were let. Throughout New Zealand up to 1886 the Government spent £501,260 ($1,002,520), either directly or by subsidy, on the construction of water races for goldmining. Now an almost forgotten section of early Public Works Department activities, it was one which helped many to tide over the severe economic depression of the IRMI’s

(By

J. H. CHRISTIE)