Harbour Commission

Hawke's Bay Tribune, Volume XVII, Issue 205, 13 August 1927, Page 9

Harbour Commission

Board's Engineer’s Evidence. FIGURES THAT FAVOUR THE INNER HARBOUR. ESTIMATES OF COSTS. Further important engineering evidence was given by Mr. Dudley Holmes, of Messrs R. W, Holmes and Sons, consulting engineers to the Napier Harbour Board, before the Commission inquiring into harbour affairs yesterday afternoon. Owing to the mass of evidence to be gone into, the Commission decided not to sit to-day, but will continue on Munday morning at 10 o’clock. Resuming his evidence after lunm yesterday, Mr. Dudley Holmes, engineer, said that the cost of the Breakwater itself at the present day, if 75 per cent was added for use in prices, was £499,000. Details of the Inner Harbour were given by witness as follow.—Depths of basin 26 feet, 30 feet in both channels and berths- - 426,000 cubic yards would have to oe dredged at an estimated cost of £26,725. Dredging the channel oetween the moles and widening to 300 feet at the bottom of the channel would cost £37,575; the construction of the mole and protection along the Western Pier would be £26,600, giving a total of £63,875. Dredging the basin to 26 feet and berths to 30 feet, 2,071,600 cubic ya.ds would have to be moved at a cost of £103,580. Dredging the channel from the Westshore bridge down to tho harbour basin—in all 850,000 cubic yards—would have to be re moved at an estimated cost if £42,500. There was sure to be some cutting back or scouring, but just how much was hard to say, but in the total of 85(1,000 yards a liberal allowance had been made. Constructing the tide diversion bank, 23.600 cubic yards at £l, would e.rt £23,600. In regard to that ban a witness stated that small pieces of rock could be used as the forces playing on it would be slight. The 1200 feet of quay wall would lost £81,200; two sheds 700 feet by 60 feet, £19,800; four cranes at £lOOO each, £4000; concrete floor in sheds and along quay, £lO,OOO. Cullen and Keele, said witness, showed in their estimate an item for lighting (buoys) £lOOO. Witness had allowed a similar sum for that purpose, contingencies and engineering, giving a total of £395,000 Roading the area to be reclaimed, £72,160; estimated value of reclaimed land, £247,000. When the ba ß m wa s deepened to 30 feet and to the same depth in the channel and 34 feet in the berth s the cost would be £20,660. It was proposed that all this material would go to further reclamation. The cost . of roading would be increased by £11,200, making a total cost of £83,360. The value of tne land was increased from £247,000 to £276,485, When the basin was dredged to 30 feet, the channel to 34 feet and the berths to the same depth, and extra dredging in the channel outside the entrance 559,000 cubic yards would have to be removed. This, at 1/3 per yard, would cost £34,875. Dredging in the entrance channel 86.000 yards at 2/6 would cost £8600; engineering and contingencies would be £3100: deepening basin and berths 359,000 cubic yards. £17,960; extra dredging in the tide channel, 34,000 yards, £1700; giving a total of £65,556. The estimated cost of dredging io 24 feet in the basin. 30 feet in channel and berths, was £395.000; cost of reading £83,360. making a total cost of £533,916. The land value was £276,485, giving a total rtett cost of £258,000. All the cost of plant had been included in the unit rates; for instance, the cost of a dredge was included in the cost of dredging. Dredging the channel outside the entrance to a width of 1300 feet to a depth of 34 feet, the extra cost would be about £lOO,OOO. PARKE ISLAND ROCK. Mr. Holmes, continuing, stated that his firm had examined the country within reasonable distance of the railway line from Takapau to Waikoau and found that with the exception of Parke Island there was no rock that they could recommend the board to use for construction work. At Parke Island there was some good shell rock, but in limited supply, being about 35,000 cubic yards. By the time the Eastern Pier was constructed and the Western Pier reconstructed and protection work constructed along Hardmge road, there would not be much of this rock deposit left. For obtaining this rock the board received three tenders, the one accepted amounting to 34/1 per cubic yard in place, the next 39/-, and the third about double. In estimating for the work at the Breakwater they had considered using for the foundation work the rock in the Bluff at the roop of the Breakwater. They allowed for 86 per cent, of spoil and 14 per cent, of rock being obtained. They considered that that would be the amount obtained and it was singular that the amount of spoil would fill the two ponds. If there should be less spoil there would accordingly be a greater supply of rock. Allowing 2/- per cubic yard for the disposing of the spoil and handling same the total cost per cubic yard of' rock would be 12/-. The cost of excavating, sorting and handling would be 8/-, making a total cost of 20/- per cuhic yard in place. He drew the attention of the Commission to the marine life tnat was attacking the shell rock in the neighbourhood of the harbour A piece produced was taken from rock that was placed as a possible foundation for an extension of the Breakwater. It was found to lie greatly riddled, after having been down for about 20 years. This rock, ", h ICt L"'?. s limestone, was taken from the Bluff near the Breakwater. In estimating the cost of the rubble foundation in the mole they allowed a price of 15/- per cubic yard, it being considered that smaller reck could be used. For the reclamation wall inside the Outer Harbour a cost of 12/- per cubic yard was allowed, the reason for the reduction being the shorter distance and in smaller material. Tn regard to gravel supply for concrete work, that on the bench at the root of the Breakwater was very fine. This was not so when the Breakwater was constructed, and supplies were obtained from the beach. Now it would be necessary to go to Awatoto to get gravel of a reasonable size for making concrete. LACK OF SAND FOR CONCRETE. Witness drew attention to the lack of sand for concrete work in the vicinity of Napier, there being no

good sand beaches. In order to carry on their present works they had to scratch for it. If large quantities were required it was necessary to go to Awatoto. As a check to their concrete prices he quoted the Wellington sea wall, which cost per yard was £2 18s. In estimating the cost of concrete work at Napier they had allowed £2 15s per cubic yard at the Outer Breakwater and £2 IDs for the West Mole. That used in Wellington was of a strength that had been found necessary to withstand the action of the sea water and it was not considered wise to use concrete in Napier very much less strength. It could hardly be said that their estimate of £2 10s per cubic yard was an excess price; the price of £2 15s for the outer Breakwater allowed for a contingency of ss.

Some little time ago, continued n'itness, the board instructed his firm to inspect the Wanganui dredge Kaione and also to report on the type of dredge that would be required to carry out the Inner Harbour proposals. The Kaione was a suction dredge fitted with either a cutter or a suction head. It was capable of discharging into hoppers or into a pipe line- The material could be pumped from the hoppers into a pipe line or could be flumped througli doors in the bottom. They had watched the performance of the dredge for some time and had estimated from the work that it was doing in Wellington that the output was 420,000 tons per year. In doing the work in Wellington a distance of about 11 miles had to be travelled, the round trip taking about 2j hours. They had not gone very thoroughly into the cost of working the dredge, being informed that it would cost about £13,500 per annum. The Wellington Harbour Board were paying about £5,000 per annum as hire. For one shift daily, allowing for wear and tear, the total cost was £20,000. The cost per cuhic yard from these figures worked out at Is s?d for the work she could do. They had taken the cost of dredging the soft materials as shown by the bores taken by Mr. Pengelly at the Breakwater harbour at Is 3d per cubic yard, the dredge having to move only short distances from its moorings to where it could pump ashore, as against 11 miles in Wellington. They could put all the dredging outside the mole at the same place, it being doubtful if it would be necessary to moor the dredge. At Wellington experiments were carried out of lowering the suction arm fitted with a cutter and steaming slowly astern without mooring and very good results were obtained. In dredging during the ebbtide witness considered that a large quantity of material would be cardied away once the bottom was agitated. This could also be assisted by every ship that came in by speeding up the revolutions of the propeller and shutting down again so as not to effect the speed of the vessel. His firm considered that the overall price of Is 3d would be high for the work. The Kaione when working inside a sheltered place such as the Inner Harbour would work more days than what she was doing in Wellington. The output should be well over three times the quantity that was being handled by her in Wellington. There she took 45 minutes to load out of the two and a-half hours, which would give some idea of the increase in output. Some allowance would have to be made for the variations in material. As far as the borings showed in the. Inner Harbour and the vicinity, and also along the line of the Embankment, the material to be dredged was shingle and silt. They had allowed the cost per cubic yard for pumping the material through a pipe line, some 2000 feet, at 5d per cubic yard. To this cost must be added the cost of boosting the material which would be about 3d per boost for two boosts with a penny contingency. The total cost of dredging would be Is a yard. The material could be forced a maximum distance of two miles which would cover, roughly, half the board's endowments. In Ooolgardie water was boosted over 300 miles. 34 FEET AT THE ALLEGED HARD PATCH. With regard to the plant that the board had, said witness, the J.D.O which was a small dredge, had been working at both harbours for about 40 years. The grab bucket fitted to the dredge worked satisfactorily in gravel and soft material but not so in the boulders or hard silt at the Breakwater. Recently the bucket from tho Browning crane was fitted when a hole was dredged down to 34 feet. in the hard patch referred to. Much better results were now being obtained from this tool. The hull of the dredge appeared to be in good condition but the time was coming when a new boiler would have to be fitted. The C.D.K., a suction dredge, was also an old amchine. A short time back, through interference, it sank at its moorings. It had since been raised and stripped of its machinery for repairs. It was about 12 years since the portion was caulked, so that an overhaul was long overdue. The Waikaka was also dismantled and they intending suggesting to the board to obtain a new gravel pump and so make one dredge that would give useful service. Dealing with the question of access to the harbours by both road and rail, witness stated that when coming from Hastings the distance to the centre of the main quay at the Inner Harbour would he about 16 chains longer than to a similar place at the Breakwater. From Taradale or Wairoa the distance was about 1 7-8 miles further to the Breakwater harbour. Wool would be always brought in by lorry along the Wairoa road, also down the laupo road, Kuripapango road, and Maraekakaho. All fruit from the Heretaunga plains would be lorried on to the wharves. In handling the goods at the Inner and Outer harbour by railway, the distance was a mile further to the Breakwater. They had based their estimates on the work done and the average railway charge of sixpence a mile per ton. Witness had taken live-eighths of the exports to be railed, taking last year’s returns of 86,000 tons as a basis. This amount at 6d per ton would be £2070. The same quantity of imports railed would total £1,340. Allowing for hauling to'the warehouses at Is per ton per mile a cost of £2300 would be incurred. Further charges for cartage to sheds at the Breakwater would result in a charge on the community of about £5,700. In the handling of the imports to Napier witness said that £360 would be saved to importers by the sheds being at the Breakwater. The difference in the two amounts was a nett saving

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in favour of the Inner Harbour of £5,380. Regarding reclamation witness stated that in order to arrive at a fair idea of the number of sections that would be obtained a plan had been prepared covering tile subdivision, up to the borough standard, of the whole area.

At this stage the Commission adojurned until Monday morning-