Overview
Sun. Feb. 18.
My 20th visit to Mangahao Hydro-electric Works. Fine cool day. Maud + I left Woodside at 8.30am with Clif + Tui Dyer in Father’s car, dropping Clyde + Nancy at Stewart’s + Marjorie’s respectively. Picked up Viv who is staying with Dora. Going up the Tokomaru Valley Road the engine got pretty hot + we gave it a spill just below Hairpin Bend. 1/4pl[ate]. photo (1) of car + party on road at this spot. This was Maud’s first visit past the Hydro-elec. Powerhouse site + she + Viv greatly admired the bush in Mangatangi Gully. On reaching Arapete cookhouse to inspect the Tokomaru Dam-site +c. The flume which carries the water
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of the Tokomaru on the downstm. [downstream] side of the auxiliary dam has been extended to the northern side of the trench excavated for the dam but except for this + the cutting of clean slips in the solid rock in the bottom of the dam-trench on right bank of the Tokomaru ready for the concrete foundations, the works at this spot are much as they were on the occasion of my last visit (Nov. 23rd). 1/2pl. photos (2) of flume + auxiliary dam. 1/4pl. (3) of flume from river-bed. 1/4pl. (4) of auxiliary dam from junction of Tokomaru + Arapete. 1/4pl. (5) Dam-trench with steps of right bank as described above. We then visited the rock-crushing plant, inlet end of Tunnel No2 as far as the control shaft, I noted several great dumps of gravel, rubble + boulders lying ready for conversion into concrete. One of the workmen also pointed out the spot near the top of Te Paki Ridge (just north of the old timber tramline) where tunneling operations are in progress in search of good rock to augment the supply of rubble from Tunnels No1 + No2 for concrete making. Returned to car passing the single men’s cottages where a big group were playing “two-up.” Reached top of Jig Tramline at 12.noon + had lunch after giving the girls their first look down the tram to the river.
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Descended zig-zag track to No1 Gorge + took 1/2pl[ate]. photo (6) from platform above dam trench on left bank looking along line of dam + showing the latest developments. On arrival at the small suspension bridge saw the damage resulting from the recent big flood. Not only had the coffer dam protecting the entrance to the By-pass Tunnel been swept clear away but a considerable mass of rock, which is here at the tunnel entrance much jointed, had also been eroded + removed, all preparations for concreting the tunnel entrance having thus been destroyed. Since the flood a new coffer dam of stout plank piling has been put in position + an electric pump installed. The concreting of the By-pass Tunnel (lining) is now in progress, the concrete being sent down a shute via the temporary sloping adit to the By-pass Tunnel. Looking down No1 Gorge from the suspension bridge it was seen that the debris from the deep excavation in the high-level terrace which choked the gorge in Nov. last had been swept away by the big flood reinstating the deep green-tinted water of its primeval state. On the high-level terrace good progress has been made with the works: The cross-trench running along the crest of the rock-rib between the old + present channels of the Mangahao is now being filled
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with concrete for the foundations of the buttressing walls of the great double dam. A newly-erected concrete-mixer stands on the edge of the high-level terrace above, a short length of tramline connecting it with the two-storey, tower-like cement store + elec. hauler building. The big bins alongside this building are now filled with sand + gravel trucked up from the dump alongside the river bank electric cranes. Another electric crane has been erected on the high-level terrace alongside the deep trench + is used for lowering + raising material into + out of the trench. Another set of rubble bins located on the bank above the store sheds on the right bank just upstream from the small suspension bridge are now surmounted with a double rock-crushing plant which deals with the big boulders collected from the river-bed. 1/4pl. photo (7) of foundations of buttressing wall of dam looking upstream. We descended into the deep trench in the high-level terrace. 1/4pl. photo (8) of party at entrance of adit into No1 Gorge. The trench has not yet been deepened below the 75ft. level (level of adit into Gorge) but the whole of the boulder formation between the lateral slopes of the old channel has now been excavated, leaving the lateral slopes as bare rocks
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at each end of the trench. The width of the old channel on the 75ft. level is about 42 yards. New vertical bracing has had to be nailed to some of the vertical series of struts supporting the side-timbering of the trench. After pointing out other features such as the entrance to No1 Tunnel, position of lower end of By-pass Tunnel , cookhouse +c, +c to rest of party, we left No1 Gorge at 1.45pm. 1/4pl. (9) of party on zig-zag track. Reached Mangaore construction powerhouse at 3.10. We alighted here + inspected boilers, dynamos +c. Reached Woodside at 4.10 after a very pleasant + interesting outing. After milking cycled down to Marjorie’s place for Nancy + had a look round their garden.