PROGRESS AT MANGAHAO.

Manawatu Herald, Volume XLIII, Issue 2297, 2 July 1921, Page 4

PROGRESS AT MANGAHAO.

MODERN SCIENCE. IN THE

WILDS.

To a party which paid a visit to the Mangahao hydro-electric works recently, it was made evident that this gargantuan task of the Public Works Department has' now taken shape, and it is possible to inspect each particular section with a clear idea of its relation to the whole. The total area over which the works will extend is either in course of transformation or about to be, and the chief impression registered in the lay visitor’s consciousness is their magnitude. In fact, it is necessary to see with one’s eyes what is being done to realise fully the nature of the task the engineers in charge have been set. A short run out from Shannon brings one to the first indication of the scheme. Here the surge chamber is shown by the excavating on the steep face of the hill, which will eventually harbfmr the pipe line, 900 feet in height, by which the tremendous electrical energy is to be generated. A provisional power house, to supply the needs of the camp, has already been constructed, not far from the spot,where it is intended to erect the big power station. The site of the station is now a steep fiillside at the end of the gully, and it good deal of excavating will have to be undertaken before the building work is commenced. Here, also, are' situated the large store houses, where the material is brought by motor lorries as it is required. The journey up to Arapeti, the middle camp, takes one over a circuitous road, which has been much improved during the past few months, but there is still plenty of room for further improvement. To drive round the hairpin bends, with the sheer hill face on one side and the deep wooded gullies on the other, is a nerve-testing experience, especially at night. The road lies partly through country which has been burnt off, though not cleared, but as one ascends to the top of the hill the road is formed through virgin bush, which presents a delightful panorama as one looks over the Arapeti Valley, of hill and ravine, bright green where the sunlight touches, and darkening into black shadows in which the trees themselves lose their form. Away beyond,' if the day he clear, the view extends to the sea, a blue margin bordering the fertile country that lies between. Soon the travellers arrive at the main camp at Arapeti. Here most of the men are congregated, but a still larger camp is in course of formation at the site of the big dams, where most of the labour will be concentrated. The lower area of the camp at Arapeti will eventually be inundated, in the formation of a dam, which will have a capacity of 40 million cubic feel, and which will be connected by tunnels with the main dam at the Mangahao end, and l.he surge chamber, which will receive the water before conducting it into the pipe line, at the Shannon end. The underground water channels which are being rapidly bored through the hillsides TOO and 900 fee I below i heir highest point, will be so and 4-7 chains respectively in length. Each tunnel is being constructed from both sides, and the toughness of the rock necessitates blasting it out. The drills for boring the charge holes are worked by com)fi’ossed air, and the work is advancing at the rate of about 30ft. a week. The chief point of interest at the upper, or Mangahao camp, is the site of the big dam that will imprison the stream. It will he ninety feet in depth, and will provide u head of water 40 feet in depth at the tunnel mouth. The upper dam, which is really a holder for sill and gravel, will spill into the main dam, and will also serve to relieve the pressure on the lower wall.