NEW HYDRO PROJECT

Chronicle (Levin), 14 May 1946, Page 6

NEW HYDRO PROJECT

DAM AT MARAETAI SET IN DEEP I GORGE Altliougli many of the equipment problems of Karapiro are not to be allowed to recur, the new 180,000-kilowatt hydro-electric projeet at Maraetai, 37 miles further up the Waikato River, is no easy oue. Tlie eehoes of explosions as loose rock is blown away at the portals of the diversion tunnel reverberate today up a narrow gorge .and over precipitous eountry fraught with difficulties Karapiro lias never pfesented. Cut offi by miles of pine" forest froni the farm lands of the east and by a vvide stretch of virtual waste land in the west, Maraetai has liad fo wait for its development on a 30-mile roading and bridging programme. The new aecess road through 13 miles of pines owned by New Zealand Forest Produets, Ltd., is complete in its lirst s'tage for ail but two miles before the river is reached. At this end a buSh road leads to a te'mporary bridge, whicli replaces the ferry which caused a bottlencck until about three months ago. Access Difficulties Possibly an even more difficuit job has been the cutting of a . Toad down the cliffs a couple of miles downstream to the tunnel mouths. It is now iive miles long, but is to be sliortened by a mile and a-half and developed to a ehain widtli. It will fnially be used as the route to the powerhouse. In addition, a Bailey bridge is to be lowered by cable from the cliJT-tops to a point just downstream from the lower portal, wliere it will give access to a flat ledge on the other side of the river for the disposal of spoil from the tunnel. From that ledge a fuftlidr road has to be carved up the other bank for the installation of two cableways which will each cover the whole construction area. These cableways, which will span about 700ft. and will each- have a capacity of 71- tons, will traverse at both ends. Of the two at Karapiro, oue is fixed and the other traverses at one end only. Other new gear includes moderu tunnelling equipment, battery iocoinotives, live-yard side tip trueks and up-to-date loading equipment at the tunnel faces. New and bigger .concrete uiixers will be used, and in general none of the inain plant at preseut at Kara piro will be transferred to the new job. Equipment is being obtained for a quarry, at a site yet to be determiucd, which will produce 200,000 tons oi metal for the dam. A sawmiil at the new township at JMangakino will cut the 600 acres of pines from tlie plantations of New Zealand Forest I'roducts, Ltd., which will be inundatod. This wood will be used for toniporary buildings, conhrete boxing and possibly for the houses of the large construction community. Dam to be 200ft. High Tlie new dam will be ■ 200ft. liiglq— ucarly twice tlie height of Karapiro- — while its length of 550ft. will be alniost tlie sanie". The powerhouse is to be sited in tlie preseut river bed in the toe of the dam, with the penstocks eomijig througli the arcli. This is still far away, however, for the dam is estiuiatcd to take at least four years to coniplcte and only pi'eliinihary work is being ilohc even 011 the diversiqn tunnel, which will be a 200ft. curve aml 25ft. in dianieter. Three camps containing over 300 men have already been cstablislied on tlie site, and each day the number grows a.-> workiuen are relcased from- Karapiro and. tlieir gcar and huts are sent on the 50-milo road journey to Xlangakino. Among thc largest buildings so far erecteil are the Avorkshops and titting slieds which will care for the tunnelling gear. As the eountry is very difficuit to tlie east, 110 road is plaimcd to cross the top of the new dam, and access to Mangakino will in timo be gained across thc top of Whakamaru dam, about eight miles to thc south. The preseut bridge across the Waikato at Maraetai will be under a lake in parts about four0 miles across. The generating equipment for Maraetai is already on order in America, and is expected to be delivered before tlie end of this year.