Overview
Thurs. Nov. 23.
My 18th visit to Mangahao Hydro-electric works. Very dull day. At 7.am received an unexpected invite from Will Kilsby to join his party on a visit to Mangahao. Left home in gig at 8.30 + drove along to the Shakara Creamery. Kilsby’s car arrived soon after 9.am, the party consisting of Will + Mrs. Kilby Gordon Franklyn + his Wgton friend, Jim Bourke + self. On arrival at the Hydro-elec. powerhouse found considerable progress had been made in the powerhouse building, reinforced concrete work well above the foundations being in full swing while on the bottom floor a series of big iron pipes of curved branching shape had been placed in position. On the pipe-line bed the small concrete piers which are to carry the pipes are not in position right down to the powerhouse.
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We proceeded in the car over saddle on Tokomaru Valley Road right to Arapete where we stopped for awhile to inspect works. We alighted at the cement stores alongside road above dam-site and had hardly got out in the open just beyond the overhead electric hauling plant located at the western end of the Tokomaru Dam excavations when a blast was fired in the bed of the Tokomaru R[iver]. far below. Two pieces of rock actually came right up to where we stood, the larger smashing to fragments on some ironwork only a few feet from us – it was a near shave. Very great progress has been made with the excavations for the Tokomaru Dam – the “cut” is now very deep at the western end, the rubble + pug formation cut through being closely timbered on either side + kept open by a large number of heavy beams placed horizontally. A narrow deep trench now extends right across from the left bank to the right on the upstream side of the main excavation. In the bed of the Tokomaru River immediately upstream from the line of excavations, a small temporary auxiliary dam has been erected + the waters of the Tokomaru [ponded?] back up its gully. A large flume has been built into this
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material which may perchance be carried into the tunnel. Resuming our places in the car we went on to the end of the Service Road + after lunch under verandah [sic] at one end of the cement store at top of Ji tramline, went on down to No1 Gorge. Several changes are noticeable here also but from above ground the additional work in the deep excavation in the high-level terrace is not visible. The deep sloping trench in the face of the left bank is now opened out right down to the water-level in the gorge. On top of the high-level terrace, the concrete-mixing plant concrete store surmounted as at Arapete by an elec[tric]. hauler with an aerial tramline, has been completed, a rock crusher {?] for gravel + sand hasve been erected on a lower [?] different levels, and the engineer’s office has been removed to a site on hillside above northern end of high-level terrace. We met Mr. Johnson the engineer, + Mr. Cooper, contractor, + the former took us into the By-pass tunnel which has now been excavation (driven) its full length of 7 chns save for a narrow wall of rock near its inlet end, + the concrete lining is also nearing completion. At the inlet end of the By-pass Tunnel protective piling has been driven into the river-
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bed and workmen were engaged in preparing to make the concrete entrance + apron + a log-screen of heavy iron bars is also to be built to protect the intake. 1/2pl[ate]. photo (3) of these operations showing pumps being adjusted +c. When this work has been completed a temporary dam is to built across the upper end of No1 Gorge to divert 3000 cusecs of the river into the By-pass Tunnel. Mr. Johnson also took us down to the bottom of the deep excavation in the high-level terrace which is at present 75ft. below the top of the high-level terrace + on a level with the floor of the adit leading out into No1 Gorge. This deep trench is now being extended eastward towards the right wall of the Mangahao Valley, + later, the remaining depth of the boulder formation lying below the adit level, will be excavated to bed-rock which Mr. Johnson informed me [his - is?] 15ft. down, giving the old channel of the Mangahao River at depth of 90ft. below top of high-level terrace. 1/2pl. photo (4) of present bottom of deep excavation showing the close spacing of the horizontal 8” x 8” struts which support the timbered sides of the trench. No1 Gorge was at this visit nearly choked with debris trucked out through the adit
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under the high-level terrace and from the excavation on the left bank, but most of this will be swept downstream by the next big flood. We next visited the inlet of tunnel No1 + the elec. crane which was working + by means of a “grab” lifting large quantities of sand from the bed of the river to a dump on the bank above. 1/2pl. photo (5) of the crane at work. At both Arapete + Mangahao a great difficulty will be to secure a sufficient supply of material for the making of concrete, and in this connection we noted as we left Arapete that the bed of the Arapete Stm. [Stream] has been stripped of all boulders along almost its entire length from the Service Road Bridge down to the Tokomaru dam-site to supply material for the rock-crushers. After pm. tea at top of jig we returned home via outward route after a very interesting visit. In evening Maud went over to surprise party at Cheslyn Rise got up by Methodist choir. Developed Mangahao + other photos. Light rain during night.