HARBOUR INQUIRY

Hawke's Bay Tribune, Volume XVII, Issue 211, 20 August 1927, Page 8

HARBOUR INQUIRY

FURTHER EVIDENCE HEARD MR R W. HOLMES AGAIN ' IN WITNESS BOX. The Napier Harbour Commission continued its sittings yesterday afternoon. Mr. R. W. Holmes, consulting engineer to the Harbour Board, continuing his evidence, said that Mr. Marchant, in his report, stated that the work of extending the Breaawater was being slowly pushed on nt the rate of £7O per foot. The Breakwater had cost £285,000. which was an average cost of £ll2 per foot. Witness could not understand how Mr. Marchant should have quoted a figure £42 per foot below the cost i the time of the date of his report, as £ll2 per foot was the average cost, including work in shallow water. Mr. Marchant, said witness, proceeded to refer to the qualitv of the concrete and after quoting the re quirements of concrete to be used in sea work remarked that more cement should be used in the making of concrete blocks, undoubtedly referring to those used in the wavebreaker. The cost of completion was estimated at £75 per foot. Further on Mr. Marchant remarked that in enclosing the harbour by a western mole would without question make it a first-class port having calm water. Then he remarked, said witness, that in order to render the water in the enclosed area as calm as possible a cant along the Breakwater and the piling up of more blocks on the wavebreaker on the second cant w’ould almost entirely stop any waves breaking over into the harbour except during the heaviest storms. TWO IMPRESSIONS Witness drew special attention to two expressions used by Mr Marchant in connection with the Spit Harbour, that the water must be absolutely calm, and in the second place deep calm water, but when speaking oi the Breakwater Harbour it appeared to be only necessary to have cairn water, and in another place the words “Cahn as possible” were used. It was not quite clear why the water in the Inner Harbour should have to be calmer than that in the Outer Harbour. Mr. Marchant was the first to refer to the destruction of the shingle and the carrying forward of the residual sand in suspension by the heavy sea. Mr. Marchant estimated the cost of completing the Breakwater to the Auckland rock at £75 per toot, or a total sum of £87,500, which included £2,000 for the strengthening of the extremity; the Western Mole to cost £45,000. one wharf to be built off the Western Mole, £31,500, and with a few other items, making a total of £184,500 In the absence of information regarding Mr. Marchant's ideas of constructing the Western Mole, witness assumed that it would be built of rubble limestone, which in its sheltered position would be suitable provided it were protected from marine life by a surfacing oi uonvrete blocks. ESTIMATED COSTS In order to place the rubble in position economically, and also the concrete blocks, the method of staging would no doubt have been adopted as at Greymouth, in which case the amount of £46.500 would have hardly covered the cost of the staging, so for this work the cost was underestimated. A wharf for ocean-going vessels required to be 600 feet ,■• length and 200 feet in width if it was to allow for railway and road facilities. Such a wharf at the date of Mr. Marchant’s report would have cost £lOO,OOO. which was nearly £70,000 more than Mr. Marchant had quoted. If the additional amounts were added to make the estimate reliable the total would be increased to more than double. If the use of the rubble Breakwater, estimated at £206,000. at the Spit Harbour be deducted from that harbour the sum ot £119,000 remained which was less than one-third than that for the construction of the Outer Harbour work —a position which was quite the reverse to that mentioned by Mr. Marchant. Recapitulating the estimate and presuming that Mr. Marchant proposed to extend the Breakwater by 1,550 feet at the actual unit cost of the Breakwater then constructed a total of £174,000 was obtained. The length of the mole was probably about 3,800 feet. Presuming that it would cost less than half that for the Breakwater at a total of £190,000 was obtained. Adding the two amounts a total of £364,000 was arrived at. Increasing that by 75 per cent to bring it up to presentday values a total of £637,000 was reached, which was a little under the cost of carrying out Cullen and Keele’s recommendations. ANOTHER REPORT.

The next report obtained by the Harbour Board, said witness, was by Maxwell. Williams and Blair Mason in 1909. Their report dealt with providing harbour accommodation at Napier for vessels of deep draught and the largest tonnage. First of all they dealt with the lnne r Harbour proposals, drawing attention to a supposed bar 3,000 feet outside the moles, remarking that the bar always existed to a certain extent but had become more pronounced since the construction of the Breakwater. The soundings taken by Mr. Marchant in 1906 disclosed a sea bottom between the Breakwater and Westshore of sandy silt and of a very even surface. These soundings practically coincided with those shown on Admiralty charts taken previously. The soundings taken this year showed that the sea bed over this area had remained practically unchanged. A bar was usually found at the mouth s of rivers and other channels through which water was discharged to the ocean, being the result of a conflict between the waters running out and the waves. There was no donbt that the bar referred to was a hindrance lo vessels that might be accommodated in the deeply scoured area outside the moles reaching to the open sen. Witness then drew attention to some former evidence given when the chart of the recent soundings was produced on which was shown a deepening near the Auckland rock and Hardinge road, and also the trapping of the silt under the lee of the Breakwater The effect of this he had not the slightest doubt, but in the course of tune if nothing be done the sea would, deepen from the Breakwater to. the Westshore. If the sea bed consisted rtf clean sands such as was found in the volcanic sands on the coast of Taranaki the erosion would occur at • much mor* rapid rat* than th*

sands which composed the bottoift at Napier, because the sand there contained a certain proportion of mud which had a high cementitious value as had all such material derived from the trias-jura from which the shingle of the Tuki Tuki river was derived.

SEA BED OUTSIDE NAPIER. The sea bed outside Napier was highly resistent to dredging either by a bucket ladder dredge or by an ordinary grab, but it yielded readily to a dredge fitted with a revolving cutter. They had recently removed the old shmgle chain grab from the J.D.O. and fitted it with a modern two-rope grab which the Harbour Board had in its possession, the result being an increase in the dredging capacity of the J.D.O. It was found that when the J.D.O. was working in the sea wav with a fair sea roll it generally happened at the critical moment that when the jaws of the grab were closing the vessel rolled, lifting the grab, thus losing the whole or greater part of the contents. Witness answered the question which was asked regarding the sand pump here on the dredge Whakariri. The dredge was fitted, he said, for use in a sea way with a suction pipe going inboard amidships, the lower end of the pipe being fitted with a few teeth for loosening the sea bed while being dragged over. It had been found that the Whakariri did not worn economically in material in Wellington similar to that at Napier. The dredge Kaione was fitted with a pipe extending from the stern of the vessel in a well. It had two fittings for the lower end, one a revolving cutter, the other being known as <i truhling head. The fruhling head would not work in hard sand because directly it was dropped on the bottom it effectively anchored the vessel and when kept just clear of the bottom and working m material similar to that of Napier its efficiency became aimost useless. OTHER DIFFICULTIES. It was also found impossible to steer a vessel when the fruhling head was on the bottom. The revolving cutter, on the other hand, worked very well ill the consolidated sand, either with the vessel moving slowly ahead or astern, or with eitner engine going ahead and the other astern, and also in the sea when there was wave action up to 18 inches. In sand pump dredges, working in material as line as that lounu outside Napier, there was great difficulty in filling the hoppers owing to the large quantity ol material that was carried overboard through agitation by the hoppers and it was estimated that it was necessary to dredge twice as much as the contents of a hopper before it became full. In dreagmg the proposed channel outside the Inner Harbour it wouid pay to only partially fill the hopper and proceed to dump which would only be a short distance away- In any case such a dredge would prove quite an economical tool, particularly on the ebt> tide wnen the revolving cucttei would so agitate the sand as to cause some of it to be washed out into deep water. Reverting back to Messrs. Maxwell Williams, and Mason’s report, witness said it was stated that the channel leading to deep water outside the Inner Harbour would be liable to be obliterated m heavy weather. They also remarked that the sand bar and sand drift were, in their opinion, the critical feature in connection .with the establishment of an Inner Arbour for the larger vessels. They also stated that in the lace ol an uncertainty ot maintaining the channel they could not advise the expenditure of large sums of money on the improvement of the Inner Harbour, tn view of the large scouring action of recent years that had taken place outside the Inner Harbonr, not only in the deep hole, but towards Westshore, witness had not the slightest hesitation in saying that once a channel was cut through the bar that the scour from the Inner Harbour, combined with the action of the propellers of vessels using the channel would keep it permanently open. It would be seen from the chart of the recent soundings that a channel over 1,200 feet in width existed just outside the moles, by which vessels drawing up to 23tt might proceed, maintaining at least 3ft 9ins of water beneath them at high water spring tides and in very fine weather vessels drawing 24ft could safely proceed. MAINTENANCE OF CHANNEL. Referring to his remarks about the maintenance of the channel by vessels proceeding through, witness said that a channel was dredged opening up two swatch-ways m tlie Northern Wairoa river by means of one of the river steamers, the vessel being moored at the head of the proposed channel by means of an anchor and also off each stern-quarter. The engines were set going and the vessel was hauled down stream being moved sideways as the deepening occurred, the waters carrying the material away as it was stirred up by the propellers- Maxwell Williams and Mason stated that a protecting mole would be required being presumably a mole similar to that proposed by Mr. Marchant. Witness said that his remarks regarding Mr. Marchant’s report applied equally well to this proposal. It was then stated that even with this mole some maintenance dredging along the channel would be necessary at all times and ultimately the travelling drift, would come round the end of the mole forming a bar and requiring constant dredging. Witness agreed with that opinion, pointing out that at the present time with the Inner Harbour moles in their present condition all silt finding its way past the Breakwater and being thrown up to Hardinge road foreshore was carried along that foreshore by the littorel drift and deposited in the swift current issuing from the Inner Harbour was carried away outwards in a north-westerly direction through the 23ft to the Westshore beach. Any a tempt to lengthen the present Inner moles beyond the one contemplated would seriously interfere with this action and would therefore be detri mental to the Inner Hnrbouf '•hamThe reference made to the 23ft which already existed north-west of the Inner Harbour moles was for the purpose of suggesting that it might be temporarily used to obtain access to the Inner Harbour by vessels drawing up to 21ft under suitable and able conditions. It was considered advisable to defer consideration of the formation of the channel outside as suggested b v Cullen & Keele until the changes which were at present going on on the sea bottom could be further studied. This delay was economically possible because it would take some considerable time to carry out the work contemplated in connection with the Inner Harbour, ihould that be adopted, while to dig

a channel through the outer bar could be accomplished in a much shorter period. The deepening which had taken place in the vicinity of Auckland Rock was of equal importance as regards both harbour schemes. TUTAEKURI SILT. The report, said witness, dealt with the silt brought down bv the Tutaekuri river, as the diversion of this river formed part of the Rivers Board’s scheme of control, u.nd in view of some work having already been carried out for that purpose and as there was no doubt the river would ultimately be diverted, consideration of river silt in connection with the Inner Harbour prouosal need not further be considered. Where the maintenance of a harbour and its approach channel depended upon the scouring action of tidal waters it was absolutely necessary that some land water should reach the scouring basin in order that there might be an excess of water flowing out, by which means the entrance of silt was largely if not completely. overcome. The Esk river and the drainage of the hills between Taradale and Petane might provide sufficient land water. Messrs Maxwell. Williams and Mason apparently did not appreciate the stoppage of the silt from travelling across the sea bottom broadcast toward the outer channel, and they proceeded to deal with the large amount of maintenance that would be necessary. In their estimate of £418.000 of works necessary for provinding an Inner Harbour, the sum of £120.000 was included for the ’-•rotective mole. They also included the sum of £2OOO for the cutting of a new outlet for the Inner Harbour through • Pet«ne beach, and then remarked that the scouring efficiency of the few hundreds of acres of watpr remaining in the Inner Harbour would not be worth considering. With these remarks one had to agree To attempt to localise a new entrance to the lagoon would brin~ about a condition which would entai] verv heavy maintenance dredging work. They then 1 remarked that the estimates were prepared on the assumption that the whole of the area wa« easily dredgeable. Taking into consideration Hie geological features of the area and the uniformity that had been obtained from borings and dredging, one had to presume thr* no difficulty whatever would be met with in connection with the dredging. NEW EMBANKMENT BORE. Reference had been made in evidence that some hard material was met when dredging with the Browning crane. Such hard material. said witness, in such situations, merely consisted of a concretion of fine materials by oxide of iron or bv lime. There was no reason to believe that any extraordinary difference would he experienced in dredging on the boulder patch known to exist in the channel, and witness had no hesitation in saving that he believed that these boulders had been derived from the protective works that used to exist along Hardinge road, from the contents of the destroyed part of the eastern mole and residue from slips from the Bluff hill. In a bore that was driven near the end of the new embankment no obstruction was met with the whole way down. He understood that the depths of the jpore was 500 feet, Some years ago witness had occasion to deal with th? removal cf a rock bar in the channel of the Helensville river, which prevented navigation at all times bv the local steamers except at water. No difficulty was experienced in the removal of the bar after using explosives The attempts made hr the J.D.O. to deepen the channel in the vicinit” of the boulder patch had been largely frustrated bv shingle which had been brought down bv the ebb tide current. This shingle was derived from erosion from the bed of the lagoon and in the vicinity of the new bridge, where the current was not concentrated. In one place a little above the bridge at the eastern encl, the channel had been deepened to about 27 feet. When the bridge was designed a uniform deepening was provided for of 15 feet low water As might naturally he expected, such deepening would not proceed uniformly, and steps had to be taken to ensure that no danger to the bridge occurred. It was necessary that a greater volume of water in the future should flow through the bridge in order to maintain the velocity in the entrance channel to ensure maintenance of depth in that channel and also in the approach channel outside. Messrs Maxwell. Williams and Mason considered that the exnense of taking borines in the Inner Harbour would be considerable. Thev did not consider them necessary in view of the conclusion thev had arrived at. presumably not to recommend thp Inner Harbour. At this stage the Commission adjourned until Mondav morning HAWKE’S BAY FRUIT EXPORT. NEEDS OF THE INDUSTRY. On behalf of the fruit-growing industry of Hawke’s Bay. Mr A. M. Robertson, fruitgrower, of Hastings, submitted a lengthy statement dealing with the future export fruit trade of Hawke’s Bay to the Commission yesterday. Mr Robertson pointed out that the prospects of fruitgrowing in New Zealand, more particularly in Hawke’s Bay. were never higher than they were to-dav. Mr Robertson then dealt with the activities of the Empire Marketing Board, whose public education schemes to buy Empire products he said, were having an effect and tesultijig in benefits being realised bv New Zealand fruitgrowers. So far the Continental markets had hardlv been touched, and when assurance on the financial aspect on the Continent was forthcoming and ships were available, he saw no reason why direct sales could not he made thus obviating the necessity of selling through Hull and other British ports A BIG JUMP Mr Robertson then stated that the total shipments* of fruit had jumped from 135,(XX) bushels in 1923 to 728,985 cases in 1926. It was anticipated, he said, that for the 1928 season 150,(XX) bushels would be sent away from Hawke’s Bay. and then onward that number should increase by 50,000 annually until 1935 when it was anticipated that 500.000 bushels would be available. With the stimulus of a few years’ successful shipping there should be great increases in planting. QUESTION OF TRANSPORT. Dealing with the question of transport to port for shipment. Mr Robertson stated' that one of the greatest drawbacks to the successful export of fruit from Hawke’s Bav was

the present necessity of having to rail all fruit to Wellington. It could be readily understood that fruit confined in railway trucks for periods up to 48 hours would ripen even to a point of deterioration. Efforts made at coo] storing in Hawke’s Bav had not been successful owing to the Railway Department not being able to guarantee insulated trucks. The latest information from the Department was that it could not see its wav to provide sufficient fruit waggons as the trade was a seasonable one and the trucks would be idle for the rest of the year The cost of railage to Wellington, he said was 9d per case which, on the present export basis, meant a direct loss to the yrowers of £3750. Cool storage in Wellington at 6d per case meant a loss to them of £2500. making a total of £6500 without taking into consideration the loss incurred through delayed transport to the present point of shipment. Congestion that was likely to occur at the Wellington wharves was also a serious matter. DIRECT LOADING REQUIRED. If facilities could be provided at Napier for direct loading into the ship, growers could deliver direct from their orchards and thus avoid the present numerous handlings nd long rail transit. By Hawke’s Bav fruit being sent to Wellington for shipment the Napier Harbour Board was at present losing a revenue for wharfage alone on the present export of 150,000 eases eaual to 3750 tons at 3s per ton. of £572 10s. Putting cool storage down at £l3O-1 it made a total of £1876. In eight years that might be increased bv a further 350,000 eases, or £4377. making a total revenue of £6253. That amount would lie a serious loss to the district, but very small to that which would occur to the growers if facilities were not provided for the direct landing of fruit at Napier.