ON THE WAY.

Auckland Star, Volume LXII, Issue 209, 4 September 1931, Page 8

ON THE WAY.

ARAPUNI RESTORATION.

REOPENING OF STATION.

« MIDDLE OP NEXT YEAR."

PROGRESS OP REPAIRS.

MINISTER OUTLINES DETAILS.

(By Telegraph.—Parliamentary B*porter.) WELLINGTON, this day. In- view of the satisfactory progress being made with the repair work at Arapuni and the fact that this is somewhat ahead of the'scheduled programme, the Hon. W. ,B. Taverner, Minister of Public Works, confidently anticipates that the station should be again running under load before the middle of next year. In an interview this morning, the Minister outlined details of the progress -made to date with restoration work. "Work - is being energetically. carried on," stated the Minister, "on practically all of the various jobs under the repairs scheme, but activities have of late been somewhat, restricted on account of inclement weather. In fact, during July no fewer than 24 wet days were experienoedV "with the result that progress on most'of the outside work was.adversely affected. Every effort has, > however, been made to maintain three shifts on the work at the headrace preparatory to the placing of the. impervious lining, and on the excavation work at the falls and the overflow, channel, these being the three;' major items, of the repair work. The number of men employed bar of late been somewhat reduced, the , reduction being largely'due to the fact that the preparatory work in the. headrace is well advanced and somewhat ah»*d of the work. Contracts Bomowhai in expess of £S<V)OO haw been

let for the manufacture of concrete paving slabs, for bituminous lining and for steel sheeting required in connection with the headrace lining. Reinforcement Process, **An interesting part of the repair' work is the reinforcement of the country at the junction of the 'spillway dam with the concrete intake emplacements. This is being done by means of inclined bores, in which long steel rods are inserted, and into which concrete is forced under pressure. Up to the present 3500 ft of such bores have been drilled, and about 4£ tons of steel rods have been placed, 2J tons of cement having been used in these holes. Further preparatory work in the nature of placing porous drains, applying bitumen to the surfaces of existing concrete, etc., has been carried out at the corner of the spillway and intake structure, and concreting in connection with the reinforcing concrete block recommended by Professor Horriell for construction at this point is now in hand. '' Grouting Main Crack. "A considerable amount of grouting work has been done 'in connection with the main crack which occurred in the headrace at the time of the breakdown in June of last year. A large number of bore holes, at various angles and extending to as much, in' some cases, as 70ft in depth have been drilled. -The total length so drilled up to the present amounts to 6845 ft. Seven tons of steel rods have been placed in these holes, and 45 tons of cement used in. their reinforcement. The placing of three porous layers of material from the headrace on which the impervious lining will later be placed is now nearly completed, the only parts remaining to be done being'the openings left for temporary drainage, and an opening over the main crack. Excavation of material is now completed in connection with the reshaping of the side walls of the headrace, except for a small block of rhyolite, on which the crushing plant now stands in front of the spillway extension. This block will later be removed. The formation of , these side banks has been handled by scoop teams, but lately the work has been considerably delayed by wet weather. The excavation entailed in this work amounted to 42,794 cubic yards, and the formation of side banks has involved the placing of 65,412 cubic yards of material. The total quantity of material handled under this section of the work to date anwunis to 97,489 cubic yards,

Countless Bore Holes. "One well-boring plant has been almost continuously employed on the drilling of vertical grouting boles in connection with the reinforcement of the eastern abutment of the main dam. This work has involved, up to the present, the drilling of 4696 ft of bore boles, and 255 tons of cement has been used in grouting these boles under pressure. Similar boring has also been taking place in connection with strengthening the western abutment of the main dam. Some 8119 feet of vertical boles have been bored at this part of the work, and 328 tons of cement used in grouting them; 1894 feet of horizontal holes bored by means of drifter drills have been done; and something over two tons of steel rods have been placed; and 3727 feet of inclined holes have also been bored at this point, and approximately three tons of cement grouted into them. "Work is also in hand on the preparation for the installation . of the new control gates in the diversion tunnel, through which the Waikato Kiver is at present being by-passed round the main dam. A pilot shaft has been constructed from the surface down to the existing bypass tunnel. A hole has been bored through the top of the concrete lining of this tunnel, and the pilot shaft is now being widened to the width which will be required to carry the control valves. The excavated material is being gravitated through the pilot shaft into the diversion tunnel,, from where it is carried away down the gorge. This part of/the work, is thus being very cheaply "handled. Cement grouting is also being done in the locality of this new control gate shaft. Some 5575 feet of boring has been done and 163 tons of cement grouted into these holes. "Repairs are also being carried out to the existing control gates in. the diversion tunnel. These suffered some slight damage when the lake was being emptied by means of the diversion tunnel, immediately after the breakdown. ; Restoring of Waterfall. "The protection of the overflow channel below the spillway dam to the waterfall is in hand, and to date 2122 cubic yards of concrete has been placed on this part of the work. _-Some 49 tons of reinforcing steel has been used and. 600 feet of porous drains constructed. "One of the most interesting stages of the work," added tie Minister, "is the reshaping of the waterfall in such a manner as will more efficiently, control the water. The excavation for this purpose has entailed heavy and difficult work, but it lias now been satisfactorily completed, and the placing of the reinforced concrete on the faS will.shortly be in hand,* " r " *