NEW LAKE AT HATEPE

Taupo Times, Volume I, Issue 49, 17 December 1952, Page 1

NEW LAKE AT HATEPE

taupo's hydro- electricity scheme PROJECT UNDER TEST After a week of uncertainty due to tne vagaries of ihe weather, Mr L. Jf"0' Engineer-in-Charge of the Taupo Hydro-Eleetricity project at Hatepe was able, about 9 a.m. on ednesday last, December 10th to order the closing of the gates of Ihe dam, and the waters of the Hinemaimaia Stream began slowly to nse behmd the spillway. Nearly 161 iZZ T' l°Ut L25 a"m- «>e folh r\ newly-formed lake fcad reachedthe top of the spillway, nd from then on the waters caseaded over the whole length of the waii ^ it was an ln.spiring> g. ,t . Mariri ,thlS Spillingr 0n Wednesday bu v ,ure 0f Pumic eollected, iSdf Sn y, m0St of ifc cleaned cam ' _J? \e iar8'e l°ss which berte wedged on the spillway were eased away by Messrs YounVaTd Morns and later Messrs Marsden and isherwood dressed for the part in r^oiid°tSthe%fd al°ng the wal1 and rocll , a , last . of the offending low saw ,Si rV'tdld S° watchei's beS clZ watSnofetfSCOlOUrati°n in ti ei ot wie cascade which quKkly passed the waters sped on to the lake. waters sce1,eTtteeSfonf eSentative visited ^e Mm f°Howing morning. Amona those present, with the superS th7chlngWeei'' Ml' ^handeno, ,were the Chainnan of the Town Boird, Mr M«Srs k"e T U'" K' OAccess to the Site. wavUratn O °ff the Main South Highy at a sign-post on ton of the ■Plateau above Hatepe, six miles of rough and bumpy road winds to a fevei hT ¥°° ** zbove sitl p6¥e dr°Ppin«' d°wn to the low Af +uneW lake 400 fee* beviJw a magnificent Of r ot- surr®undinS' country, and Lake Taupo from Mt. Tauhora to Karangahape is unfolded.. Thence the road snakes downward. Far below is the .scene anticipated for months past — the water of the Hmemaiaia banked up behind the eoncrete spillway to forrn a shallpw lake, and flowing over the spillway— laupo's power sehenie a reality of construction. Impressions in the Spot. At a first impression the new lake seems small in area conipared with the layman's expectation of what would happen to what originally -ooked like and extensive water-shed °r- One even envisioned an outstanding knoll in the landscape converted into an island. Actually, the surface area is approximately' 60 acres. It eouid be enlarge'd at fome future date by raising the height of the spillway. The finished project at c!ose juarters is a neat pieee of engineering con-struction, and the rnost has been made of the contour of a catchment aT ea and dam site ideally suited to the purpose. The spillway has been soundly constrncted into the solid rock along a line beyond which the stream, plnnges dov/n a fall of 120 feet. The pent up waters are reieased into the penstock leadjmg to the turbines, 120 feet below, at a point on the ex|reme left of the spillway (lookipg down-stream), known as the Fore Bay. Pediments along the top of the spillway break the force of the overflow at regular points. By daylight about 20 hours after ihe gates were closed 4 inches of

water was pouring over the spillway, spreadmg out and channelling a new path to the old river bed beyond, the two falis — the old and the new, converging at a point about 100 feet below. The new waterfall is a most picturesque sight. The power •house with the generating plant are protected against waters of the overflow by a strong concrete retaining wall leading from the Fore Bay to the bridge below where the building is situated. The power-plani; itself, a 15C- kilowatt unit which is to supply current in the meantime pending the arrival of the 1,000 Killowatt turbine (now on the water), was given a test run on Wednesday and Thursday followmg the closing of the gates, and appear^ ed to function smoothly and efficiently. Tihat part of the power-house in which the larger turbine is to be installed has still to be roofed. Difficulties Overcome. Although the Taupo hydro scheme is a comparatively miodest one in scale, there were major problems to be solved, and difficulties to be overcome. On a previous visit to the scene in company with Mr Mandeno, the Times was given some of the facts. There was the preliminary survey to be undertaken. The country had to be explored by Mr Mandeno on foot. There were no tracks. What seemed at first to be a suitable site for the spillway was abandoned in favour of the present site, higher up, with a better fall. This decision having been taken, the next problem was the access road to permit of the transport of men and materials to the job. The road construction involved the expenditure of considerable labour, time, and money before the main task could even be apprbached. Scatching for Materials. The project, moreover was launched at a time when the supply of es-sential materials such as cement was extremely precarious, contractors everywhere having to lead a hand-to-mouth existence. The problem of poles for the transmission line and the reticulation of the town was a pretty tough one. Along the line are to be seen steel rails from the Wanganui tramway tracks, larch poles from the State Forest at Rotorua, steam-treated pinusinsignis poles. Again, the transmission line from the power house to Earthquake Gully had to ihave some considerable spans on account of the rr-:gged nature of the countrv. Gnc span, from the power house across the ravine to the t-T of the hill on the opoosite side, is half-a-mile in length. Asked about the effect of wind stresses on cables siung- from poles so widely separated, Mr Mandeno said that due" allo vance ha,d been made to provide for a swing of as much as 100 .feet, and the cables 'had special attachments to ease the stresses at the Pcle connections. Furthermore, in a span of such length it had been xound that a twin-cahle provided a compensating action that made for better resistance to wind stresses. He also pointed out an interesting feature of the transmission system, mainly, that prooably for the first time in New Zealand, the cables used were of aluminium. The Official Switch On At the time of writmg, the date for switching on the current to Taupo had not been fixed. It is undeistood that an official check-up of the project by Departmental Engineers is required before the business of current supply can be inaugurated. Present indications are that the final touches and the official check-^ up may be concluded before Christ-

mas, possihly in time for the official switch on to be recorded in our next issue. But there still remain a good j deal of finishing off work to be done, and much depends on the weather conditic-ns in the meantime. Assoeiated with Mr Mandeno in the later stages of the project were Mr G. Mandeno, representing the Engineer-in-charge at the scene of operations; Mr J. Sherwood, the Taupo Town Board's resident electrical engineer for the Tapper Construction Company; antl Mr D. Thomson, foreman of works.