WATER-POWER

Dominion, Volume 11, Issue 15, 12 October 1917, Page 8

WATER-POWER

THE WELLINGTON SCHEME PLANS FOR NORTH ISLAND DEVELOPMENT Plans for tho development of waterj power in tho North Island aro discuss*]-' further by the Chief Electrical Engineer (Mr. Evan Parry), in a- report attached to the Public Works Statement. 11 r. Parry presented an interim report in February last, and on that occasion sketched schemes for tho Auckland and Wellington, districts. "Tho survey of tho transmission lino between Shannon and Wellington has been completed," says Mr. Parry, "and the survey staff transferred to the Auckland district, where they aro now engaged in completing a survey of a transmission lino between Auckland and Cambridge, on the Waikato Kiver. A survey for a transmission- line from Shannon,, through Palmerston North, to Wang-.i-nui, should bo the next in order. Auckland Prospects. "In the interim report reference was made to tho development of water-power on the Waikato River at the Arapuni Gorge. The eourco has a good deal in its favour to recommend it. The capital cost for the ultimate development is remarkably low,, whilst it is within the economical limit for the initial stages, and it is favourably situated, as regards tho principal market and as a supplementary or even principal source of supply to the Wellington district. The development, however, necessitates the construction of. a dam 146 ft. high, involving difficulties and unknown-risks; and, following the advice, of the Engineer-in-Chief, tho possibility of utilising the Kaituna Biyer, or the Waikato Eiver at tho Aratiatia Bapids, is being further investigated. Neither • compares favourably .with the Arapuni development as regards capital cost per horse-power developed, provided, of course, that no abnorbal difficulties, are encountered. On the other hand, the capital cost can bo ascertained moro definitely in the two former cases, and further investigations aro proceeding in the meantime. On the advice of the Eugineer-in-Chief a Tcpoi't waa obtained from the Mines Department on. the" geological features of the Arapuni Gorge. The survey was jqaUe by JDr. Henderson, and his report is on the whole-favourable from'a geological standpoint, and geological faults are absent. In view of tho possibilities of this development it -would seem desirable to carry out extensive prospecting works for the purpose of ascertaining the nature of the foundations and sides and of testing the suitability of the rock to withstand' water-pressure. . Power for Wellington. "A survey of the power requirement of the Wellington district has been put in hand, and up to date tho power requirements have been ascertained for the following districts—namely, tho Ilutt Valley and the Mana-watu district botween Wellington and Palmerston. A visit has been paid to the works of every power-user, their power requirements ascertained, and particulars obtained of tho fuel consume*], cost of maintenance, and particulars of engine and boilers. These havo been tabulated and located, so that tho power demand can bo determined to a very close approximation and tho cost of transmission and distribution estimated within fairly narrow limits. 'This work will bo <.on- | tinued and. completed its soon as possible, tho noit district to receivo attention being that between Palmerslon North and Wanganui, after which tho Wairarapa district will recoivo attention and also tho Hawko's Bay district as far as Napier." The interim report discussed in somo detail the availa.blo sources of supply of ■water-power in the Wollington district. "It has been suggested," wrote Mr. Parry, "that tho Hutt River would form a, suitable eoiltco for supplying tho southern end of tho Wellington district. Tho amount of water is barely adequate for the needs of Wellington City if provision is to be made for natural growth and progress, whilst for. the amount of power availablo the cost of development is excessive. In any case tho amount of power obtainable is not large enough to supply an extended district, whilst_ a power-station .in the Manawutu district is well situated, for supplying Wellington, Wairarapa, and parts of tho Hawko's Bay and Tn.ra.naki districts, having regard to the distances and the power lo bo supplied in each locality. The Mangahao River. . "After considerable investigation tho most suitablo 6ourco for the 6upply of the southern district is found to bo the Mangahao River. • This river rises on the slopes of Mount Dundas, on tho Tararua Ranges, and flows into tho Manawatu near Woodville, and it is found that by diverting through tho hillH for a total distance of thrco miles thero is made available the fall of 1040 feet, in the 65 miles of river between the Mitngahao and tho loop of the Manawatu near Shannon. It is proposed lo develop (hie soujco by tunnelling through the range from th* Mangahao into the Tokomaru Valley, thero diverting a part of tho Tokoma'ru, and then from the Tokoraaru Valley through into tho valley of tho Mangaore, with a powor-station situated within three miles of tho railway at Shannon. "Observations of tho flow wero made during last season, which was exceptionally dry, and are also being mado during tho present season, and based -upon tho dry-season flow it is possiblo to obtain 25,000 horse-power on a 50 per cent, load-factor basis by impounding' tho waters and taking advantage of tho natural features of the country l for tho purpose This is sufficient to satisfy tho power requirements of tho district which it is intended to servo for Bomo lima to come, but will require to bo supplemented in due coutfio ae the country develops. Tho natural extensions of tho 'transmission lines from three sources will ultimately link them together, so that bv this means security will bo obtained, wild also additional supply obtained for tho Wollington district from the other sources. It is possible, however, that in course of time the requirements will ue so great as to requiro another development in tho Taranaki district, where there is moro than ono promising Mr. Parry suggested further that tho existing steam plant in Wellington should bo used as a stand-by in conjunction with the water-power scheme. Tho cost of providing - head-works, power-station, aud plant for 25,000 norse-power would be at normal prices .£420,000. This illustrated tho advantage of concentrating the power supply for a considerable' district in one source. "If, for instance, we sought to provide for tho needs ot Wellington City and immediate neighbourhood only from this eourco," said Mr Parry, "the cost of hydraulic works for' the p'owei required would be excessive, whereas when developed for the Ml capacity and for the benefit of a larger area and population it becomes a sound commercial proposition. "As regards tho area to be supplied, thero is an economic limit to the area 'over which a given amount of power can be distributed, and one of the obstacles to a satisfactory scheme of power supply in New Zealand at present is thn small amount of power required pel squaro mile of area supplied. Having regard to this principle, and stretching it "to tho limi , :, we should be working on economical lines in serving the following districts from this source:-Ihe whole of tho Wellington Provinco as far north as Taihape aud Wanganui, aud the southern portion of Hawkes Bav I woul'l propose, in the first place, to run trunk lines to Wellington, Palmerston North, Wanganai, and Masterton as chief centres, and from these centres, as well as from interrogate points on the trunk line, to provide the necessary distribution lines and substations to 6ervo the surrounding districts." '