PROPOSED RESERVOIR POR TUAPEKA GOLDFIELDS.

Tuapeka Times, Volume I, Issue 12, 2 May 1868, Page 3

PROPOSED RESERVOIR POR TUAPEKA GOLDFIELDS.

The following extract from the report of Mr. Mil||r, F.S. A., which ■ we clip from the "Daily Times," on the construction of a reservoir for r the Tuapeka Goldfields, is well > worthy the careful study of every l miner in the district. The scheme * is one of the most practicable and \ payable ever contemplated by the ; Government, and, if carried out, > will certainly prove a most success- ; ful undertaking, and redound to \ the lasting credit of the present Government. We hope to refer to the project more fully on a future occasion : — As a site for the chief reservoir in this locality I have selected a spot which may be properly designated as the Tuapeka Basin, lying in a northerly line, midway between trigonometrical stations (1) and (X), and at a distance of about four and a-half miles, in an arrow line, from the Town of Lawrence, from which its bearing is slightly west of north, and about half-a-mile east of the Tuapeka River. This site, from its peculiar ichnographical features, position, altitude, and shape, will, on being embanked, form as fine a combined collecting, storage, compensation, and distributing reservoir as I know of, impounding the winter rainfall for a continuous summer distribution — thereby not only affording, but ensuring to the miners a constant water supply of great magnitude and hydraulic power, as compared to anything heretofore attempted in New Zealand. The site is in the bed of a natural basin, particularly favorable from its altitude, being upwards of 200 ft. above the "Blue Spur," and is encompassed nearly all round by elevated ground, quite capable of being converted, at a comparatively small expenditure, into a magnificent reservoir of 100 or 130 acres in extent. The banks are of suitable slopes, and apparently of firm retentive subsoil. The bottom or bed of the valley is an extensive flat of the like impermeable material, and the space where I purpose throwing the embankment across is unusually narrow, as is evinced by the sketch of the outlet " gorge " herewith, and eminently favorably situated for obtaining all the material requisite for its formation. For approximate estimate of cost and sketches, vide addenda to this report. { It will be seen from my calculations j that the Government will be enabled to ! afford to the mining interest water at a very reduced, indeed almost at a nominal, cost, if they (the Government) but seize, impound, and economise the advantages which nature has so abundantly, in fact lavishly, placed at their disposal in these ranges, lying as they do at a high elevation, and partaking of the humidity arrested by the still loftier Blue Mountain Ridges "from the rain-bearing clouds, which partially discharge their waters east of the Clutha — thus becoming the main feeders to both the Tuapeka and Waipori Rivers, a3 also the Beaumont Burn ; from whence, in addition to the rain-gathering surfaces lying above the contour lines of the main race, I purpose taking the main supply by intercepting weirs of a permanent character. Tliis would secure an inexhaustible supply of water, tend to give a stimulus to goldmining, and tend to attract population to the Tuapeka fields. The commanding altitude of the site which I have selected for the distributing reservoir, by adopt- j ing judicious mechanical arrangements, | may be made subservient to an increased hydraulic pressure, and aid in washing down the auriferous spurs which are j known to exist. The power would far j exceed that at present in operation. It would, in addition, command a large extent of auriferous country, now unwork- j able for want of an abundant and cheap water supply. It will be found sufficient to profitably employ a population equalling the whole of the present mining population of the Province of Otago for many years to come, were they congregated in this one neighborhood. Taking the area of this reservoir approximately at 100 acres (which I am satisfied I under-estimate) within the water perimeter, and at an average of 45 ft. deep — the embankment being 100 ft. in height —it will contain 1,221,204,000 gallons (say upwards of j twelve hundred and twenty-one million gallons) of water — equal, after being once filled, to the supply of 217 race-heads of water, allowing the liberal quantity of 75,000 gallons each head, per working day of eight hours, for the space of seventy-five consecutive days, exclusive of Sundays, supposing no rain whatever to fall during the period of three months (a thing not at all likely to occur in this humvdTclimate or locality). Note. — By way of elucidation I shall draw a comparison with the foregoing computation of 217 heads, by stating that the present total supply to the Blue Spur from seven proprietary races, is but a total of twenty heads during the heaviest rainfall, five of which yield so uncertain supply for about half the year that the proprietors are obliged, perforce, to purchase water of the other owners, whose sources of supply are from the bed of the Waipori, their races being, it is affirmed, about thirty-five miles each in length. If an allowance of half time be made as the maximum, during which the five smaller races can be in operation, it would reduce the twenty heads, said to exist, to an average of 16 or 17 as against 217. The annual available rainfall (50 per cent.) over a limited extent of say twenty i square miles of country (much under the the actual quantity), , would afford 5,210,472,960 gallons, deducting from , which 327,972,960 gallons for evaporation, leaves 4,882,500,000 gallons for consumption. Keeping in active opera- ; tion the 217 race-heads named, flowing day and daily (for 300 working days), ir- : respective of any drought which may ■ perchance occur, all the year round. ; Allowing 17 heads free, as an equivalent . compensation to extinguish the present 1 vested water-rights at the Bine Spur, j would reduce, the total payable heads to . 200, which,' calculated at a price not ex- > ceeding one-fourth of the present exorbit tant rates paid by the miners, would yield to the Provincial Treasury a reve-

[, nue of £10,000 per annum — a sum sufficient to defray interest and extinguish the capital required for construction within a very brief period. There is already, witliin this district, situate on the north-east side of Wether- . stones, a small bxit regularly constructed ■ reservoir of some fifteen acres in extent, capable of storing a considerable quantity ' of water, the property of a Company known as the "Phoenix" Water-Race Co., successors to the defunct Wetherstones Dam Co. This reservoir has been constructed at a cost of about £4000, and is well placed to command the Wetherstones Flat, and other sluicing claims upon the numerous surrounding spurs, which, to a considerable elevation, are composed of the same description ef cement — and which I believe to be a\iriferous — equalling the now- celebrated "Blue Spur" itself. If the water was stored in sufficient quantity to enable the Directory of this Company to supply the miners abundantly, and at something like a third or even one-half of the present rates charged, these spurs would be teeming with industrious miners, extracting a rich reward for their labor ; a matter for the immediate and serious consideration of the Government. To accomplish this, however, the present embankment would require to be raised twenty feet or more, and the catch-water races supplying the reservoir, extended for some ten or fifteen miles eastward, embracing a large surface of rain gathering country, the water of which now finds its outlet in the Waitahuna river, to the detriment of the miners at Havelock. There is a capability of making an improvement in the working of this reservoir, as a matter of water-economy ; that is, to construct a new bye- wash, having its overflow over the hollow of the eastern saddle of the Waipori road, instead of the northern end, as now, from whence the surperfluous water, in times of flood, would find its way to another reservoir site, known as Mooney's dam, almost equal in extent to the first, but on a slightly lower elevation. This, if embanked, similar to the Wetherstones, would be capable of storing several millions of gallons of water, now running to profitless waste. The upper or Wetherstones reservoir is particularly well adapted to afford to the town of Lawrence a constant water supply, by having an additional " service reservoir " upon a small scale, constructed on a hill overlooking the town on its northern side, with an open contour channel communicating between the two reservoirs. The main supply pipe should be laid down the slope of the hill to the lower level of Ross Place, having wellplaced ordinary and air valves on the line, from whence sub mains wouid have to be laid to specially appointed places, at the option of the Corporation, supplying <; public service stand pipes ;" or, by adopting the usual system of reticulating pipes laid down the principal streets, the water could be conveyed into every dwelling or store, by the ordinary house connections and high pressure taps.