MIKONUI WATER RACE, WESTLAND.

Mount Ida Chronicle, Volume VI, Issue 347, 30 October 1875, Page 3

MIKONUI WATER RACE, WESTLAND.

("Extractfrom 'Report.) The District Engineer, Hokitika, to the Engiaeer-in-Chief. • District Engineer's Office, Hokitika, 27th August, 1875. Sir, —-I have the honor to forward herewith the plans, sections, schedules, and estimates of the recent re-survey of the Mikonui Water Race, and "to report as fol-

The total length of the race-line, as now proposed, is 15 miles 55 chains. This includes a branch race, 17 chains in length, in addition to the main race. -

In the preliminary report upon" this survey, forwarded, with report in June last, a statement was given of the probable character of the works which included a considerable quantity of boxing; but, after consideration, I have"thought, it better to. recommend that tunnelling should be adopted instead of boxing in every place where it is practicable, and the following is a list-of the works as now recommended: mis. chs. Iks". Fluming ... " 0 70 94 Boxing' ... - 0 ' 79 29 Tunnelling ..... ... -6 69 66 Ditching... 6 74 71 Total ... 15 54 61 The total estimate for the work as nowrecommended, based upon a carrying capacity of 50 heads of water, which is as much as it would be abvisable.to calculate from the Mikonui as a source, is £68,000 ; and I believe that, in this case, the sum estimated may be looked upon as closely ap proaching to the probable cost. In arriving at it,..the greatest care.has been used to ascertain the quantity correctly, and to adopt the highest scale of prices paid on the most recent "similar works undertaken by the Government. . The fault in previous estimates , for water-races in Westland has not been so much a want of care as a want of time, and an absence of such accurate information in the matter of surveyed details as would afford an opportunity of going .into detail. • It had therefore to be assumed that the prices would be similar to those paid on the then existing examples, and that the race§ fj themselves wonld also be similar to existing ones in the character of their works; but the rate; of wages increased very considerably, and the Government races were constructed on a" scale of efficiency and durability, particularly in the matter of the class of timber used, which had never previously been attempted in the locality, so that there was no real relation between the basis assumed for the estimate and the works as carried out. "',''

In the present case, however, the most minute detail has been gone into, and the only elements of any degree of uncertainty existing in the estimate are the costs of the head-works and the price of the long tunnel.

The former of these is necessarily uncertain, as surveyors were most diffito get, and there was not time for those obtainable to do more' than lay out and plot the race-line itself. Jn the case of the long tunnel, the element of uncertainty is the question of the. hardness or otherwise of the rock which may be met with, for'although I have no doubt miners could be got here who would tender for it at a reasonable price, and take all the risk, it has to be borne in mind that, not being capitalists, they would have to throw it up it the price did not keep them in food. As the rate estimated, however, for it is 30s. per cubic yard, I do not think that there would be much danger of that contingency arising. Even from the point of view from which the subject was then regarded, (report August 1875) however, I should have been much more inclined to have given it a hearty recommendation had the then proposed line presented a reasonable prospect of security from slips and from damage which might-cause heavy "expenses for repairs ; but it did not dp so, and hence the'large'sum which I estimated for

maintenance.and supervision. It is in this element of security perhnps more than in any other that the new line has the advantage over the old one, as tunnels are the most durable of all classes of water-race constructions, and-= in the new route tunnell : ng prevails. There was also another item which I omitted to consider sufficiently . when writing report of Ist August, 1872, above alluded to, —namely, the probability of the race water being used in connection with high-pressure turbines for the drainage of Ross Flat, which drainage has since had to be abandoned inconsequence of the great cost of steam power there.. Roughly estimated, if the water were applied with the fall head' available, ..and. carried through reasonably large'pipes, each head of water would'be equal- to 30-horse power net, and, if solcTToiJ .■'£2o per head per week," the cost to the purchaser would be equal to 13s. per horse-power. per week ; and* when it. is put in comparison with the fact that the cost of steampower averaged oyer £2 per horse-power per'week, which I.have ascertained from several inquires to have been the case, it is evident that per head per week would be a low charge for all water used" in pumping. The anticipated returns, However,.which were given in my report above alluded to, were based on a rate of '£h per head per week, to that, if some water were "sold at £2O; the returns would be considerably in excess of ;those estimated. ..< -.-' : . .

There is, finally, one more important point which I presume it is my duty to mention, as it has come prominently before me during thei time -1 have been engaged on the supervision of the survey—namely, the very depressed condition of Ross at the present time,-and;the effect which this is producing on the trade of Hokitika.

Since the earliest settlement on the Goldfields here the activity or otherwise existing in the mining of the Totara District has already been sensibly felt in Hokitika, and this is more evidently the case now than it has ever been before, so that I believe that if the workings in and about Ross were to entirely collapse, without reasonable prospect of their' being resumed again, a large proportion of the population of Hokitika, who are dependent on the earnings of the Ross* miners, would have to leave the-country. So far, however, the miners at Ross, though working under great disadvantages, have been imbued with ' such an amount of confidence in the ultimate richness of the district that they have held on there at a lower rate.of remuneration that they would- have done elsewhere. This they have done in the hope that some economical and efficient means might be "adopted for draining ; the flat to the lower levels, vvhich are at present, almost untouched ; but they cannot continue to live upon this hope for an indefinite period.

So far the Mikonui Water-race has been looked upon as the most effectual atid probable means of getting this done, latterly the hopes cf the'miners have almost centered upon it If it is undertaken, or a guarantee given that it will be undertaken, the population in Ross will probably remain as at present until it is completed, ■when it would no;doubt largely increase ; if it is finally determined not to undertake it, the majority of those now at Ross would leave the West boast altogether, carrying with them a large number of the inhabitants of Hokitika, and thus a useful body of trained miners —trained, too, in the particular class of work required at Ross— would be lost to the country. ' ' It may be as well also to mention that if this {race is undertaken on the;,, line at present recommended • its progress "will necessarily be slow, as it would take at least three yeats to complete- the .'long tunnel. I would recommend, therefore, in the event of its -being decided to undertake it,, that this \ tunnel, • which is - estimated to cost about 5612,000, should be let by contract first, and the remainder of thework then withheld for a year or two.— I have, &c, '■"' ''''■ "'•" C.'Y. O'Connor, j District Engineer; i The Engineer-in-Chief, Wellington.