Napier Harbour Works.

Progress, Volume VI, Issue 2, 1 December 1910, Page 481

Napier Harbour Works.

No. 111.

View of the Inner Harbour taken on the same clay as those showing the Breakwater being buffetted by the Pacific billows. Notice the calm security in which the shipping lies at rest.

The Harbour Board having received the proposal of Mr. George Nelson for the construction of an Inner Harbour, referred it to a Commission of three en—Messrs Maxwell. Williams and Mason. They informed Mr. Nelson to that effect in April, 1909, and furnished

him with a copy of the order of reference. Mr. Nelson replied, throwing light on various points of the order and a copy of his remarks was forwarded to the Commission. The Commission reported in July of the same year. Regarding the inner harbour, they said that the travelling drift would he a great difficulty. This drift of sand passes round the breakwater, and but for the opposition of tllO GUU DUUViUUi! J.IUXII OllU IUUCI U(U UUUI , would spread out towards the Petane beach. It now no doubt, assists in forming the bar which is found at about 3000 feet outside the moles at the entrance to the inner harbour, and on which the sea breaks during heavy weather.

This bar always existed to a certain extent, but has become more pronounced since the construction of the breakwater, the ebb tide, owing to the stoppage of the shingle drift, being now able to prevent its being spread out towards the beach while the accumulations in the neighbourhood of the entrance have entirely disappeared owing to the stoppage of the supply of shingle. They examined the bottom by dredging with the Board's grab dredge "J.D.0." from this bank inwards, and 'found that. the bottom was composed of sand to about 2000 feet from the end of the eastern mole, thence inwards it was composed of shingle increasing in size as they approached the entrance. In the entrance they found limestone boulders as described in the reports of Mr. Weber, one of the Board's former engineers. This sand bar and the sand drift are, in their opinion, the critical features in connection with the proposal to establish an inner harbour suitable for the largest vessels. "Even if it were practicable at a reasonable cost to cut an unprotected deep channel through this bar inwards, of which we have some doubt in the face of the fact that it is exposed to the heaviest seas, there is no doubt that in heavy weather it would be liable to be obliterated, wholly or in part, in which event the port would be closed until the channel was re-opened, which would be an intolerable inconvenience. ' ' In addition, they dwelt on the difficulty of the navigation, concluding reference to this point with "in the face of this uncertainty we could not advise the expenditure of large sums of money on the inner harbour until it were proved that the outer channel could be maintained at a cost that would not be prohibitive." j-iiGn tiiey went on to recommend uiie erection of a mole alongside this outer channel at a cost of £120,000 for its protection. Even with the mole there would, they declared, be much need for continuous dredging "though the cost might not b« prohibitive."

: The Tutaekuri river, they proceed to declare, is an embarrassing feature in connection with the scheme. After going into some details of the proposal of Mr. Nelson, they conclude by advising the only solution possible to be the turning of the Tutaekuri into the channel of Ngararuro, which they admit to be a most difficult and uncertain project. The cost they state at £415,000, including the mole aforesaid, and the supply of dredging machinery. This estimate, they point out, is on the assumption that the whole of the proposed area of ' the inner basin is easily dredgable by suction dredge, indicating at "the same time that there is reason -to believe that : Mr. Napier Bell's surveys, which only extended some 11 to 16 feet'below low water, indicated hard bottom in several places. They recommend careful borings, especially as it is likely, in their opinion, that the limestone rock, of which the Bluff is composed, may be met with before reaching a depth of 30 feet at low water. They admit, of course, that the reclamations proposed by Mr. Nelson as an integral part of his scheme would be valuable, but they think these might be

made anyhow, and, therefore, have no bearing on the question of his scheme or any other. This is their conclusion —• "On the whole, the risks and doubts attending the formation of a deep water basin inside are so considerable that it does not appear to be a scheme which commends itself. Had it originally been the intention to construct a basin in this position, the breakwater works should have been started further west, so as to have given more complete shelter from the drift and from seas impinging on the entrance, and a workable scheme might then have been more easily elaborated. "The inner harbour will probably always be popular with the small craft and should be properly maintained, and if for any reason a greater working depth be■f iiri-i/\v» tn r\ \) IV \_/\yJ.JL \iXk\j XXX\Sl\ji3 %J\s \.L\J&±X. V,\.Lj UIIV>X \j »V J.XJL WV/ no great difficulty in procuring it, as the velocity in the entrance is not sufficient to interfere with the working of a modern hopper bucket ladder dredge. If one could be hired, a depth of 20 feet at high water "slack" could be obtained in a few

months. A greater depth than this would not be of much value unless the outer bar was also dealt with, which we cannot recommend. At the same time it must be pointed out that unless the extra depth over the inner bar is required for the small vessels, there is some objection to deepening the channel, as it would undoubtedly admit more range into the inner basin and the "iron pot," and the range there is sufficiently troublesome already. '' They proceed to recommend the completion of the Breakwater harbour, and they compare the cost of the two projects. The cost of the Breakwater completion they place.at £270.600, and the maintenance at £59,350. as against the maintenance cost of the inner harbour of £68,250. Lastly, Ave may add they assert that with the inner harbour all is uncertainty, whereas with the Breakwater project is one of the surest and simplest and most certain possible. Mr. Nelson lost no time in replying, early in September. He pointed out, first, that the report in no way recognised the order of reference. Then he entered into the details of the condemnation of the inner harbour project by the Commission.

Recent Boring Results. Since the foregoing was written, borings made by the Napier Harbour Board have dispelled all doubt regarding the suggested presence . of rock in the Inner Harbour. Opposite the Co-operation Stores bores Nos. 1 & 2 were taken to a depth of 36ft., and struck a stick of drift manuka between 20 and 25ft. (clearly showing that the whole deposit is silt). This is an eye-opener indeed. Why, this is the very spot where the chairman of the Napier Harbour Board, Mr. I. Vigor Brown, said rocks "stopped" the pile-driving in a speech at Hastings two nights previous to the taking of the last £300,000 loan poll, at a meeting of the ratepayers, that when building the breastwork the contractors were unable to drive tiic pij.es, to ii.o hard ■>•-">* -■'«-«-•"- which, he declared, was met with at a depth of about 20ft., and that "they had to drive the piles with a crosscut saw," meaning that they sawed the tops off instead of sinking the piles. The ratepayers are now asking, "Where

is the man who made the borings for Mr. Napier Bellwhose plans show rock at 10ft. below low water?" Shrewd Criticism. We add an independent analysis of the most destructive form from the pen of an advocate of the Inner Harbour signed "A Farmer's Advocate." Trouble! —not met half way, but introduced in the very first sentence. A travelling trouble, and it travels past one channel entrance to the detriment of the other! It is to travel considerately miles away past one . breakwater and necessitate the construction of another; to considerately add a mole costing £120,000 to the Inner Harbour scheme. And this is the first point emphasised. Why was not the first point emphasised the undoubted superiority of the Inner Harbour if it could be constructed ? The next point emphasised is that no shingle drift will affect the Breakwater entrance, but a probability of sand drift passing by increasingly in a southern direction is suggested. Why? That it may block the entrance to the Inner Harbour. Why will it pass the entrance to the Breakwater Harbour? And if the ebb current meeting a sand drift arrests it and

causes a deposit, it follows that if the ebb current is itself arrested the sand ; drift which has so considerately come so far will travel on. The sluicing action of the lagoon is the chief force in that ebb current, and with the damming of the sluice most of the ebb current which it is suggested causes the deposit will cease to create a bar and the sand drift will considerately travel on to the Petane beach. The report goes on: "It now no doubt assists in forming the bar which is found at about 3000 feet outside the moles at the entrance to the Inner Harbour, and on which the sea breaks in heavy weather." Why the word "no doubt?" Was the report not obtained with a view to eliminating all element of doubt? Here huge doubt is assumed because no proof is forthcoming that "this bar has become -MifiVP -.-i-A-nri-i-i-i-ir.i3.-l ciinoa tlno r-.-.-.-■ ci>-rir.+ir>r» nf the Breakwater." We only have the bare assertion and not the comparative sounding of depths, nor necessary analysis of deposits. , ■ And now we have the ebb tide for another reason putting it just in Jthe right

place again to bar the Inner Harbour. I am not clear how or why the stoppage of the shingle drift affects the ebb tide and X makes its current more industriously create a sand bar out of sand drift which has . considerately come so far past the Breakwater Harbour entrance. Were the engineers? Is the sand bar and the sand drift, which is the critical difficulty in front of the Inner Harbour scheme, caused by a deposit from the Tutaekuri river, or has it considerately come so far past the entrance to the Breakwater Harbour? The engineers say "no doubt," but what proofs do they adduce? The report proceeds to emphasise the depth of the channel which Mr. Nelson's scheme proposed. Seven feet was all that had to be artificially created. Why is emphasis laid on the 33ft. depth? The use of the next expression "heaviest seas" and another "no doubt" explains why. If ships can make a narrow Breakwater entrance in the heaviest seas, why not keep a channel easily widened and in a much more sheltered position? In the face of all these uncertainties ("no doubts"), the report goes on "we

could not advise, etc." But it was the uncertainties these men were paid to set at rest! They appear to me from their expressions to have been paid to create them. And now we get (following the report) : Another breakwater to cost £120,000, which ultimately would not be treated at all considerately by that sand drift which passes by the other breakwater, but which would ultimately form another bar to this one! The engineers excel the sand drift in creating bars and embarrassing features! The silt-bearing river which is to create half a million for the State and another half a million for individuals; the weir which is to impound and minimise ebb currents the embankment which is to .carry our country road and railway to Gisborne. "What embarrassments! j» ... It has been shown by the engineers that • the sluicing action of the lagoon causes the water bar to be deposited. Then why not f.i-jppv if arid let, the 'onlv overflow be i slow river filtered of its mud, and deprived of dangerous flood water by an overflow channel in another direction ? The report goes on "unfortunately there are no records to show what the amount of silting in the Inner Harbour amounts to

per annum the difficulty, however, etc. " Whatever is the source of all these intricacies of difficulties and misfortunes in the minds of the reporting engineers? Is the wish their father ? And why is the rock in the Breakwater so comparatively soft, "that it can be easily broken" and removed and the cost calculated, whereas "before any reliable estimate could be made of the cost of excavating the basin of the Inner Harbour careful borings would have to be made over the area, as it is quite likely ("no doubt") that the limestone rock of which the Bluff is composed would be met T ith." Isn't it the same bluff rock in the Breakwater Harbour The report goes on "in the face of the fact that we have come to certain conclusions." Based on what, I ask? On "no doubts," "very likelies," "intricacies," '' uncertainties, " " embarrassing features," "critical features," "unprotected deep channels," "ebb current disadvantages," "sluicing advantages," and "travelling troubles." Now, immediately we arrive at the consideration of the Breakwater Harbour the

difficulties somehow become "greatly diminished," "slight indeed," "easily dealt with," "less liable to damage," ' ' quite probably not required. '' The wind becomes of "less account," "it is practicable to hold the largest' vessels against a cross wind," "the movement slight." Yet seas have been known to break right over jetty, ships and all, to smash the Breakwater clean away, and the only hint we have that there is any recollection of them still in the engineer's minds is the suggestion that the structure has been made of concrete which is not impervious. "Links that may snap!" "Intricate and far-reaching considerations," "prevailing conditions and possible results," are not allowed to enter into the engineers' minds. And although the question is raised of bringing suitable 20-ton blocks 20 miles by railway, the cost of doing so has,not only been "carefully considered," but omitted altogether. There are. some difficulties but "suitable arrangements could be made." "The proper and safe handling of large vessels in a small harbour" is a far reaching trouble which a travelling tug easily tackles. The same tug "easily maintains depths" before so doubtful.

In calculation of comparative costs, a mole and other inventions are introduced to the extent of close on £150,000 and the value of land reclaimed which may ultimately run into a million is omitted the disadvantage of the Inner Harbour. In their conclusion, the reporting engineers give the whole show away, for on the one hand it is assumed, that by the "leisurely methods" of the Board the construction of the Inner Harbour. be delayed, while, on the other hand, in discussing the Breakwater Harbour, the engineers say if the Board pursues an active policy how much can be done. In my mind there are no intricacies, no doubts, no uncertainties, and I pronounce the report on the Harbour a work calculated to thwart Mr. Nelson's scheme. It is not without precedent. (To be concluded.)