TIMARU HARBOUR BOARD.

Timaru Herald, Volume LIX, Issue 1963, 26 December 1895, Page 3

TIMARU HARBOUR BOARD.

- «+ — .. A special meeting of the Tiniaru Harbour Board was held on Tuesday, to receive Mr Bell's report on the harbour problems, and to confer with Mr Bell if necessary. There were present Messrs 0 . Talbot (chairman), J. Sullivan, J. Wilson, K. Thew, G. Lyall, G. B. Bullock, W. Evans, J. Wreathall, A. C. Pringle, J. Manchester. The chairman explained the reasons for calling the meeting. MB C. NAPIBB BELL'S COMMISSION. Statements of the questions submitted to Mr Bell, by the chairman, and by Mr Maxwell, were read. The following is the chairman's statement : — " Statement of the present position of matters relating to the shingle accumulation south of thebreakwater at Timaru, with a short resume of recent events leading up thereto ; also a few of the chief points m the questions submitted to Mr Napier Bell, M.l.C.E.,forhis opinion :— •• About the commencement of the year 1891 the Board began to feel seriously alarmed on account of the evidently rapid outward growth of the shingle bank.and instructed Mr F. W. Marchant, M.1.C.E., who was then m charge of the works as resident engineer, to report and advise as to the best means of dealing with the difficulty. Mr Marchant recommended the mechanical removal of the annual drift, as being the best and cheapest means of preserving the safety of the harbour. The proposal, however, met with violent opposition from several members of the Board, and also largely by ratepayers of the harbour district. As a result of this opposition, MessrsG. Y. O'Connor and J. Goodall, Ms. I.C. E., were asked to report on the question, with the result that they recommended the adoption by the Board of their engineer's advice. They further pointed out the danger of the situation, and advised that no delay should take place m dealing with the difficulty. This report did not allay the hostility to the measures proposed, and a few months later Messrs R. .Wilson and Napier Bell. Ms. I.C. E., were appointed a commission to report. The result again was to ememphasise the gravity of the situation, and to recommend the idea of the mechanical removal of the shingle. The Board now decided on procuring the necessary plant for carrying out these oft-recommended proposals. In the face, "however, of much Ditter opposition both from some members of the Board and ratepayers, the plant was ordered, and matters were m this position when an election for a new Board took place, which resulted m a majority of member* being returned opposed to the removal of the shingle. "The engineers services were now dispensed with, and the works remained during the tenure of office of this Board without an expert m charge. The Board recognised, however, that some action was necessary, and proposed to carry out an extension of the breakwater, starting from the elbow. The requisite consent of the Crown was withheld, however, m consequence of an adverse opinion from the Royal Commission appointed to report thereon. The plant ordered by the previous Board came to hand, but no steps were taken to put it to the work intended for it, and nothing further was done during the tenure of office of this Board, which ran out m January of the present year, when an election again took place. 11 The shingle bank had now advanced sufficiently to nearly exhaust the retaining effects of the breakwater, and its being carried round the end of it could only be a question of a very short time. Under this condition of things Mr J. P Maxwell was appointed as consulting engin-* eer. Mr Maxwell at once took up the consideration of the shingle difficulty, and recommended the Board to allow the shingle to drift around the works, expressing the greatest confidence that no serious consquences will result to the harbour, and that the shingle will create no impediment to navigation m the entrance ; that although there will be an active tendency to form a spit, the drift will spread over a considerable area with no great depth generally ; that a large proportion of it will be carried past the entrance by the sea action, and that any tendency to the formation of a 3pit can be checked effectually by the dredger "A considerable amount of doubt exists as to the wisdom of the course recommended, and also anxiety as to the consequence of its adoption, should events prove their engineer to have been mistaken m his calculations. It is under ibese circumstances that your opinion

and advice is sought by the Board, and I now ask your consideration to the following points: — "A.— Will any considerable quantity of the drift pass the entrance without causing much shoaling m the fairway ? " B.— Will the tendency be to form a narrow spit from the end of the breakwater across the entrance, or will the drift flatten out considerably to seaward ? 4 ' C— Can the dredger, m view of rough weather and probable accidents, also m view of the intermittent conditions under which the passage of the drift will take place, be depended upon to keep the entrance open, and maintain the present depth of water ? " D. — In the event of your being unable to advise m the affirmative to the latter proposition, what steps do you recommend the Board to take ? 41 E. — Would the construction of 500 feet of breakwater, or any lesser length, be of sufficient utility by way of providing better facilities for dealing with the shingle difficulty, or for providing shelter to the harbour entrance, or for both those objects combined, to justify the Board m incurring the necessary expenditure, and if so, from what point should the work start, and what direction should it take ; also of what material should it be constructed ?" The following were Mr Maxwell's 41 Memoranda for the opinion of Mr C. Napier Bell, M.I.C.E. :— 4t The documents specially submitted for consideration are : — 44 (A). Mr Maxwell's report of April 25th, 1895, and plans. 44 (B). Mr Merchant's survey plan, July, 1895, made m pursuance of the report. 45 (C). Mr Maxwell's report July 2nd, 1895, re extension m rubble. 44 (D). Mr Maxwell's report of August 30th 1895, covering plans for an extension m combined rubble and concrete blocks. 44 From Mr Marchant's survey it- has seen ascertained that the accumulation south of the breakwater has been at the rate of 70,000 c. yards a yeav during the last two years : also that about 1,000,000 c. yards have been accumulated m Caroline Bay during the last 7 or 8 years. 44 Mr Maxwell's opinions are, as regards the shingle question, that the travelling detritus will be partly driven across the entrance and onward, and partly deposited under shelter of the end, and that there will bp an active tendency for a spit to form, but that the entrance can be lcept open by dredging. 44 The Harbour Board desires to obtain -Mr Bell's opinion on this point, being anxious to feel assured, whether it is advisable to rely on dredging m and around the entrance alone, or whether further precautions are necessary. 44 Mr Maxwell has prepared plans for the Board for an extension of the breakwater at the entrance for the object of diminishing the send m the harbour and affording a better shelter to ships entering or leaving port m southerly weather. He has fixed the direction of the extension as shown on his plans, for reasons explained m his report. "Some members of the Boai-d desire to see the extension carried out from the end parallel to the wharves, to serve more effectually as a trap for the shingle. The Harbour Board desires to obtain Mr Bell's views on the question of the extension and its direction. "The Harbour Board would also be glad to hear\Mr Bell's views on the question of the accumulation of silt inside the uorth mole. 44 The Board has arranged with Mr Maxwell to confer with Mr Bell, and to give him any information necessary." MR BELL'S REPORT. Report on present condition of sand and Bhingle deposits, and a proposed extension of the breakwater. 24th December, 1895. 44 To the chairman of the Harbour Board. Sir, — Acting on your instructions I have made a careful inspection of the accumulations of sand and gravel round about the harbour works as shown by the advance of the foreshore on the north and south sides of the works. I also took a number of samples of the bottom by grab dredge, and inspected the new soundings shown on Mr Marchant's special survey. From these new soundings I have shown on a chart of the bay the alterations which have taken place m the contour lines of depth as shown m the survey for Sir John Coode, taken io. 1875, and Mr Merchant's survey of 1895, from which it is plain enough that all the shoaling has taken place by the advance of the deposits m Caroline Bay. On the east or weather side of the breakwater the depth is scarcely affected between 1875 and 1895. On the west or lee side, however, the advance of the deposits has been enormous. The 6ft line of 1875 is now dry land ; the 12ft line has advanced towards the N.E. 14 chains, the 18ft line 13 chains ; the 20ft line 8 chains ; the 22ft line 13 chains, and the 24ft line 12 chains. The lines of contour, if the soundings were extended, would probably show that o the Dashing Rock, which is otic mile N.N.VV. of the entrance, the soundings are either not affected or are deeper than they were m 1875. Contours under 20ft are formed m a hollow bight under the lee of the breakwater, and soundings over 20ft are unaffected soutli of the breakwater, but bluge out seawards at the end of it, tending to join the old contours as they get near the Dashing Rocks There is an isolated patch of shoal water round the end of the breakwater, but the water is rather deeper than it was originally close along the breakwater from near the end to very close up to low water mark, The low water mark now is 150 feet inshore from the outer end of the wharf, having advanced 550 feet since 1891. From the time the breakwater was commenced m 1878 the beach of Caroline Bay and northward of it began to wash away to the northward, and this went on until about 1886 when the breakwater was nearly completed After 1886 the beach of Caroline Bay began to fill with sand which now began to deposit over the bottom of the bay, causing the advance of the contour lines as shewn on plan herewith. No one, I think, denies that this sand has travelled round the breakwater from the south beach. Mr Maxwell has made an estimate of the quantity of this deposit, and finds it to amount to about one million of cubic yards, and if it has taken 9 years to reach this quantity, the rate is about 111,000 cubic yards yearly. The rate at which the shingle accumulates on the south beach is variously estimated between 60,000 and 70,000 c. yards yearly. There had been an immense amount of diverse opinion as to wiiether the shingle of the south beach also drifts round the breakwater together with the above mentioned sand. It appears to me that the danger to the harbour , by permanent shoaling of the entrance comes from the shoaling out of Caroline Bay, because if this advance of shoal water was not taking place it would make little difference m the depth of the entrance whether the shingle travels round the breakwater or not, as the waves would always clear, it out and cany it away to the beach. But the advance of the shoals of Caroline Bay towards the entrance is a feature of the case which is difficult to deal with for the reason that not being an isolated shoal, but being founded on the dry land, it will extend its shoaling influence a long way out and certainly far enough to involve shoaling all round the entrance, as m fact it is doing at present as shown by the contour lines on plan. If the shingle of the south, beach is not at present going round the breakwater, then the shoaling process at Caroline Bay is not taking place so fast as it will do when the shingle joins forces with the sand, and to try and decide this question I devoted some time. In the first place Mr Maxwell told me that he visited Caroline beach after a succession of heavy storms, and found it covered with small gravel and a little shingle ; this is now covered with sand, so I dug a number of holes m the beach at about l.w.tn. and a row of holes about a chain and a half above l.w.ra. In every case

I we found some fine gravel and pieces of ■ shingle, with layers of coarse dark sand and pieces of small gravel at various distances down. I then took out the Taniwha and took up specimens of the 1 bottom m about 30 different places, as shown on plan herewith, and a list is given of the results found. The features indicated by these dredginge are shown on a plan herewith which shows that' commencing about the toe of the slope of shingle at the south beach there is an unbroken stream of gravel and shingle of all sizes about 150 feet wide right out to the end of the breakwater ; outside of about 150 feet from breakwater the sliingle gradually diminishes m quantity to SQO feet out, where none is found; that the coarse dark sand with grains of gravel extends under the top layer of mud and yellow sand much further out than the shingle ; that towards the end of the breakwater this stream of gravel widens considerably, thinning out to about 650 feet square off the wall, where none is found ; that everywhere the stream of gravel is bare for about 150 feet out from the wall, beyond which it is covered at present with yellow mud and yellow sand, the inference being that m heavy weather this top layer of mud and soft sand is at once swept away and the stream of shingle and coarse dark sand is laid bare to the action of the waves ; that immediately after passing the end of the breakwater the shingle, gravel and coarse Hark sand spread like a fan, the denser part of which lies W.N.W. from the end for 12 or 15 chains, thinning out to nothing at about 20 chains south from wreck buoy, also' thinning out towards Caroline Bay, but existing m layers and patches buried m yellow sand right to the beach; lastly, thinning out towards the north mole, alongside of which there is a wide belt of mud and fine sand. As this stream of gravel is perched on top of recent deposits or mixed through it, it appears improbabte that it is derived from the old sea bottom, as some assert ; indeed I cannot imagine why the original sea bottom should be torn up and its underlying shingle strewn on top of new deposits of sand; besides which there should on this supposition be some place where the stream from the south beach stopped and the torn up old sea bottom be^an, but I found the stream unbroken from its origin at the south beach to the uttermost limits where we found it deposited. The Timaru has dredged away from the front of the entrance thousands of cubic yards of coarse dark sand, small gravel, and shingle precisely similar to that on the south beach, and there are thousands of cubic yards more to be dredged round about the entrance ; m fact from observation it appears that about § of all that she dredges is material of this kind, as very little of the fine yellow sand is saved m her hopper. It would appear from borings taken during the construction of the breakwater and from the experience of the divers that the whole of the bay for a long way out has first a layer of yellow mud, then several feet of sand, then shingle resting on clay of unknown thickness. This old bottom of shingle so far from being disturbed by the works, it appears to me, is being still further buried beneath new deposits of sand, and the appearances favour the supposition that the stream of gravel, shingle and coarse sand is spread by the violence of the waves over and through this new deposit of fine yellow sand, and that they all come together from the south. There are so many different opinions strongly urged as to the source of this drift gravel found at and round about the entrance, that people are m doubt as to its true origin. It is a pity that instead of speculating on the subject more observations were not made by dredging, soundings, and with floater, so as to try and form correct conclusions, and to ascertain the condition of things during the past five or six years. Some people think it is impossible that the waves could disperse the shingle and small gravel m such a wide area round about the entrance, and that it could not by this cause travel up the tising slope of the sea bottom to the beach. It is difficult to say what the waves can or cannot do, because no one can examine the bottom m storms, ' but m storms the driving and lifting action of waves may be combined with jpowerful currents so as to scatter deposits far and wide, and it is a common observation that stones and- heavy material are brought by storm-waves from deep water and thrown on the beach. In heavy weather the whole of the bay m front of Timaru is a mass of heavy breaking seas, which must have a powerful action on the bottom ; the lighter sands would be kept m suspension, and the strong under-tow would spread it a long way out, while thelifting and driving actionof the breakers wonld drag heavier material ashore. There are persons who think that the accumulations found m Caroline Bay have drifted from the north, but although some small quantity may have drifted by eddies from the north, I think it is very improbable, and the appearances are against the supposition, that the great deposits shown by the contour lines of soundings have come from anywhere but the south. In the midst of the doubts thrown on the subject by such conflicting evidence and opinion, it is my impression that for the last two or three years the shingle and small gravel, together with the dark coarse sand, which form the mass of the material of the south beach, have been drifting m annually-increasing quantity past the breakwater, to be spread during heavy gales all round the entrance, and that some of it is gradually washed ashore on the beach of Caroline Bay, mixed throughout with vast quantities of soft yellow sand. From the analogy of the similar position which the drift shingle and sand assumes against the breakwaters of Greymouth, Westport, and New Plymouth, I am inclined to think that the south beach here is now at, or very near, its permanent position, that it will not advance any more, or only a chain or two more and then stop. When it stops all accretions of new material drifted from the south will travel along the outer kant of the breakwater m deep water and be spared over the sea bottom round about the entrance as at present. In 1891, when Mr R. Wilson and I examined the shingle accumulations of the south beach, they were 550 feet farther m shore, and the shoaling of Caroline Bay was beginning to be noticed. If the dredging oi shingle on the south beach had been started then and continued till now, it is possible that this subsequent exteusion of the beach would have been checked; but m the present condition of the beach I feel some doubt as to the entire efficacy of dredging, from the south side of the breakwater. If the Board had the means to do so I do not doubt that it would be a good thing to keep constantly going both dredging at the south beach and dredging at the entrance, But within the last year or two dredging at the entrance lias become imperatively necessary, and I think it is now best to concentrate allefforts to dredgingat theentrancp. Having the impression that the south beach has advanced nearly as far as it will go, and that much of the accumulations coming up from the south are now travelling round the breakwater; I do not think that some additional quantity due to the south beach advancing a chain or two more will make a very great difference m the quantity which must be dredged from the entrance. The water is too rough at the entrance for any extensive patches of shoaling to lie long, for as long as there is deep water inshore of such local shoaling the waves will wear it away and drag it towards the shore. 1 find by inspection of Captain Clarkson's soundings round the end of the breakwater that silting is always taking place there ; nevertheless there is no differences of depth between August 1890 and August 1894. there being deop water inshore as far at least as the bend of the north mole, the silting is continually washed away ; but the serious shoaling which is most to be feared is that which is slowly creeping out from Caroline Bay, The drift material along

the breakwater from the south beach must always be intermittent, and prevail only during rough southerly weather. Supposing that the total quantity is correctly estimated at 70,000 c. yards a year, and that there are ten occasions m a year with rough southerly weather, this would give 7000 c. yards aa the quantity drifted round the breakwater by one such occasion. This Is only an approximation to the actual facts, but it serves to indicate the nature of the drift. From the above considerations I agree with Mr Maxwell that no great , and sudden shoaling of the entrance will take place ; the shoaling will be gradual, which if left untouched wOuld soon block the entrance to a serious extent, but if worked at constantly by dredging it can be kept down so as to allow of navigation on 19ft or 20ft. at low water. - The dredge Timaru can raise about 9000cnbic yards a month, and a year's working of 10 months would give 90,000 cubic yards. As the quantity of both sand and shingle which is drifted up from the south is now or soon wiU.be ajbout 48Q>000 cubic yards a yedt^sll 1 paSsfng ' round the breakwater, it is seen that the utmost the Timaru can do is far short of the total. The Timaru will, therefore, be able to ke^p the entrance open, though it will not be able td stop the shoaling of Caroline Bay. "It is proposed'tb'make an Extension of the breakwater from theend with., the' object <Jf sheltering vessels on entering and to cheek the range inside. This will undoubtedly shelter vessels entering, and m rough weather they enter at present under considerable risk of being stranded on the breakwater ; but I doubt if it will have much effect m lessening the range inside the harbour, and I think the best way to avoid the; rafcg^ is. to make use of the north mole for berthing large steamers, >yhere the range isj not so much felt. The only way to get; rid of range is to have a large harbour* with a small entrance, arid m all haS>! bours I have iidticed that the. range Is! most felt on the weather iside. Regard-; ing this extension of the breakwater, itj is to be observed that one cannot, under? these conditions of drifting deposits,! have a sheltered' entrance and a deep' one at tjie same titriei for it is the vio-> lence of the Jwaves which maintains the! depth. Under shelter of the extension* there will be extensive shoaling formed: m the shapeof a spit; but, I do „ notdoubt that dredging will be ' done' more effectively under shelter of the extension. Mr Maxwell insists that the direction of this extension should be 3p degrees east of the line of the breakwater, the line of the inner portion , of "the; breakwater being 45 degrees. Tliere can be n<»; dotjbt{tbat;< $hfl Csmatttjtl th« Brf gfe the better will be the shelter afforded. On the other hand 'it is strongly; urged that the fairways should^ Dt( I forced over towards the west as little aa possible, and that m case of a spit forming under the extension, the fairway? would be forced too much towards the west, and they therefore urge that the extension should be, built out at 45 degrees from the breakwater. The best way I can think of to get over this difficulty is to shift the outer end of the extension to the position it would occupy if it were set out at 45 degrees ; that would be 75 feet eastward of Mr Maxwell's proposed end ; and from this position of the end build the extension at the angle of 30 degrees to the breakwater, so that it would be parallel to the direction chosen by Mr Maxwell's and 75 feet further east. If it were now built the same length of 500 feet and with the end as far out as proposed, it would leav<? a >gap 60 feet wide from the slopes of the extension (if it were built of rubble) at h.w.m. to the r breakwater. To close this up to h.w.m. with the same leugth of extension it must be shortened from the end 100 feet, making the end measured from the end of the breakwater 1 equal to 400 feet. As the extension is not a favourable thing for preserving deep water at the entrance, I would prefer that it were shortened as much as would serve the purpoae required of it ; 400 feet out may be found sufficient, and it can always be lengthened at any time. I would recommend that the extension be built of rubble, heavy rock being placed on the sides and end. A rubble breakwater is always preferable to a concrete one for safety and security from accidents, and it is only where heavy rock is not to be had, and a concrete wall is cheaper, that a concrete breakwater is to be preferred. This extension will not stop the drift sand or shingle ; it may cause the stream passing along the breakwater to be wider and higher; probably it may cause a beach of shingle to form at the angle between the two walls. J would not advise, however, that any attempt be entertained to make this extension serve the double purpose of sheltering the entrance and trapping the drift also* for its direction would not serve both purposes; and trapping the. drift could be much more effectually done by a wall m a due east direction either from the end of the extension or from the outer end of the curve m the breakwater. It will take nearly a year to get the proposed extension started ; but if i t were proposed to go on with dredging at the south beach m the meantime as a matter of precaution, it would take about the sometime to, make any noticeable impression on the south beach, while the Timaru would be diverted from her work of dredging at the entrance. The dredging at the entrance is of most importance, and, therefore, unless the Board is prepared to provide another dredge, I think it is, ady isabU? tp restrict the dredging, to the entrance onlyv H V* /' "If the Board cannot see its way to building the extension of the breakwater mentioned above then I am of opinion that dredging on the, south beach would be of advantage to assist that done at the. entrance, as every cubic yard taken iaway at the south beach is so much less to be removed at the entrance,, To do this dredging as Mr Marchant proposed by making the underside of the wharf into a bin to hold the shingle is a very good way, and the fact of its being twice dredged is nothing against this method if it costs no more than dredging at the 'entrance. 'Dredging twice is constantly done m Sydney and Melbourne m a very economical manner; the dredgings raised m the harbour being discharged into the water close to the shore, where another dredge sucks it up and discharges it on land. Mr Marchant has shown me his emifnattrforthis double dredging, which coated, $er cubic, yard discharged out ats-feaj-but adding 20; per cent, to his estimate would....bring the cost up to 6»i Ser cubic yard,, which ia the cost of the redghig done at thfc entrance by the Timaru. The objections to this method &i 4 thas the removal of th# shingle from the bin under the wharf is hampered by the use of the wharf for steamers, while dredging on 1 the beach opposite the wharf keeps the wharf exposed to the flying water and spray coming over the breakwater, and this is the most serious objection. It could be met by construct ing a high parapet, but the parapet wpuld seriously obstruct the dredging. Under, these circumstances it would be better to erect a groin of rubble stone 3 or 4 chains long just beyond the curve of the breakwater and pointing due east. This groin would trap the shingle beyond the wharf, so that the wharf would be protected and the shingle could be dredged without interruption. A groin of this description, 200 feet loagl with heavy rock on the slopes would oost about £11,000 l but as I said above, that m the present position of th<;ljesch having extended so far and being so near the curve of the kant m the breakwater, I feel aome doubt as to the entire efficacy of dredging on it now, consequently I think it would be wiser to purchase another dredge with the £11,000 the groin would cost, and use it m dredging at the entrance. The wharf could then be protected with a high parapet wall, costing about £4 a foot or lese if made m strong timber work. These considerations lead back tp the conclusion that dredging at the enr trance has now become the most effec» tual. " Having now discussed all the pointa affecting the questions submitted for

my consideration, I will summarise the conclusions 1 have come to m the order m which they were submitted. " A.— The whole of the drift will pass the entrance, the lighter sands being spread over a large area, the heavier sands and gravel over a much smaller area, and these will shoal the entrance. "B.— There will always be the tendency to form a spit under the lee of the breakwater, but this will be only the crest of a considerable area of drift spread round the entrance. " C —The dredger will be able to keep a navigable channel open on 19 or 20ft of water, if kept constantly at the work, and if every precaution is taken to reuair damages quickly, as well as to prevent them by such improvements m gear and manner of working as experience points out. "D. -To procure another dredge and work it also at the entrance. " E.— Although the construction of 500 ft 6f extension bf the outer end of the breakwater will lead to the growth of a spit under its shelter, more than the present entrance does, yet there are undoubted advantages to be gained m the greater safety of ships entering the harbour, and m the greater advantage of dredging under its shelter ; also from the fact that the sudden appearance of a spit at the end of the extension would not obstruct the entrance to the extent that a similar spit would do from the present end- Ido not think the extension will have much effect on the range, •< and if it were not for the safety of ships entering I should think that the security of the port would be better served by securing another dredge, as the one m use may be disabled at any time, and it would not be advisable to leave off dredging even for a short time;" "Attached to this report is a plan showing what appears to be the position of drift material at present, a plan showing old and new contour lines of soundings, a > plan shdwing position of specimens of dredgings:; taken, to test the limits of drift gravel, and at end of this reporta list of material found by these dredgings. "I have, etc., C. Napier Bell, M.I.C.E. Mr ! Bell produced the plans referred to. , Qne showed that between the survey" inHde' in 1875 for Sir John Coode, and that made by Mr Marchant m July last, shoaling had taken place from Caroline Bay m a broad band past the outer line of the harbour works, and the band spread round the works to a certain extent. Another showed by shading the area over which the shingle had been drifted from the south, a narrow band at the curve of the breakwater spreading out as it advanced and sweeping round into Carolide Bay like a horse-tail. The i third plan was marked to show where \ trial dips with the grab were made, from which the above shading was drawn, and a list was given of the results of the several dips. The report having been read, the Board were invited to ask Mr Bell any questions, and for over an hour questions and suggestions flew thick and fast, only Messrs Manchester and Lyall saying nothing. The following is a resume" of the discussion : — Among the first answers given by Mr Bell were, that the suggested groin at the curve would cost about £11,000 ; 500 ft at theend, Mr Maxwell estimated at £33,000. As to the length of the extension, the shorter the better, but the steamers were 400 ft long. That, however, was rather a question for nautical men. Mr Thew spent some minutes m endeavouring to explain certain theories he had long held regarding beach lines, and asking for Mr Bell's corrections if any were required, until the other members showed impatience, and the chairman hinted that the members had better reserve their own opinions m favour of hearing Mr Bell's. In reply to Mr Wreathall,Mr Bell said the shoaling from the bay would eventually extend a long way out, so that they might have to dredge through Bft or 10ft of shoaling ; but that was m a distant future, especially if they dredged m the meantime 90,000 of the 120,000 tons per annum, coming up. It was calculated m 1891 that a dredge could deal with the whole of the annual accumulation, but the dredge had not been able to do so much as was expected. The chairman pointed out that the dredge had not yet been tested m a body of shingle. Mr Evans asked what was the objection to an extension at the bend, stopping the shingle there, and doing away with dredging altogether. Mr Bell replied that the sand would still come along, and that was their worst enemy. Mr Pr ingle asked if an extension at the end would not take the line of shoaling m the bay further out, and cause shoaling at the entrance. Mr Bell said it would be difficult to say where the final line of low water would, be, but there would always be shoaling under the lee of the extension. To Mr Bullock: Would rather not have an extension so far as dredging work is concerned. The more violent the waves at the entrance the clearer it would be from shoals. There were, however, other considerations, such as safety of entering. The argument for an extension that the dredge could not work outside m all weathers had little bearing on the matter. The dredge could work better under an extension, but the shoaling would still be outside. She would still have to. work m the open. The port would certainly be more open for vessels coming m. *Vas satisfied that the shingle that had been dredged was beach shingle and not old bottom. It was thesameißor^of shingle, with coarse dark sand ; very heavy coarse sand ; the sand m Caroline Bay is soft and light. The southern beach material had been going past for a long time. There was a powerful current running along the breakwatei m heavy seas, which carried stones a foot forward, as the waves lifted them a foot. (Mr Bell showed by a sketch plan what has been observed at Westport, where a shore current has been seen to cany floats even against the seas. If the dredge were to break down when a lot of drift appeared m the entrance, the board should send to Port Chalmers for "Dredge 222" at once, as quickly as possible. — (Mr Bullock : That would be expensive.)— "222" works cheaper' than the Timaru, if you could trust it outside. It would be better to have a second i dredge ; would rather have a second dredge than an extension. To Mr Evans ; There was no talk about shingle shifting at Westport or Greymouth, because there they have powerful tidal currents and floods. When there are no floodSj shingle forms a bar, and on one occasion blocked the place. But powerful floods cut through, and everything is carried away to the north. It is the same at Greymouth, and Gieyrnouth has been blocked up". Mr Evans : Then if the dredge breaks down we should he m a regular mess. I hold that we should go on extending the breakwater from the bend. We have had n good many years' experience m favour of that direction.— That would not get rid of dredging altogether. There would always be sand drifting round ; a groin, he thought, would not stop that, The chairman: Mr Evans thinks that by extending at the bend we should get rid of the shingle difficulty. How much would it cost yearly P and wp,uld it give any shelter to the entrance ? Mr Evans : Yes, it would give shelter to the outer kant so that we could put wharves there. Mr Bell said that would be a bad place for wharves, on the weather side of the harbour. As to extension from the bend, 400 ft run to the S.E, would have more effect than 6Qoft straight out. Mir Evans : 'For £3500 a year we co,uld put down a good lot of rough rubble work m that direction,— how much ? Mr Bell : About 80ft. The chairman: You say the shingle has gone out 500 ft since 1891 ; is there any reason to expect a lesß rate of advance against an extension on the same line m future p Mr Bell saw no reason to expect less Mr Evans said the shingle hai been

nearly 20 years going out 1200 ft, and MiBell replied that it was a long time before the beach adjusted itself to the new conditions. They could not take the whole time and average the accumulation. No, the spending of £3500 a year on an extension or groin would not save the cost of dredging ; there would be continual ahoaling round the entrance. Mr Evans : And we can do nothing with it ; the pump is a failure. Mr Bell replied that the dredge can do as good work with the two grabs. A dredge like "222" might not answer. She was nearly wrecked" by going outside. Mr Sullivan askea if it would not be safer to extend from the bend and keep the shingle as far away from the entrance as possible. Mr Bullock said that had been proposed before, and the Royal Commission would not have it. Mr Bell said that he saw no object m an extension from the end straight out. It could do nothing but trap, shingle, and a shorter length would do as much if placed end on to the seas. Mr Sullivan replied that he did not care what the direction was so long as they stopped the shingle. Mr Wreathalis'discxissed with Mr ;Bell the proper direction for an extension at the end. Mr Wreathall saidthat the ratepayers would never agree to such a work merely to shelter the entrance; but if it would also trap shingle and save a few years' shingle-shifting, he believed they would agree to it. Mr Bell said that the proposed extension, if placed parallel to the wharves, ; would, retain only a small amount of shingle; it would not retain it m the same way that the: present work does, on account of the run i of the waves along the kant from the curve. They could not, he thought, combine shingle trapping and shelter; but they could gain shelter by an extension of 500 ft. and trap shingle by adding a groin at the end of it, end on to the seas; say 300 ft. long. There was not much difference between 30 and 45 degrees. Mr Maxwell's idea was that 30 degrees would allow the waves to spread the deposit more widely. To Mr Wilson : The groin.at the end would not have any ill effect on the range m the harbour. Mr Pringle: Would you rather have an extension to reduce the range, or wharves at the north mole out of the way of the range ?— (Mr Evans : There is range all over.)— Mr Bell : You cannot get rid of range m a harbour with an entrance so wide m proportion to its size. The chairman : Your view of the spread of the shingle deposits outside is from the actual results of the dredgings ? —Yes.— lf you had not had that ; if you had only seen the seas running would you have judged that the shingle would spread like that ? Yes, because there is a powerful current there. (Mr Bell explained how the current is set up by reaction of the outer arm on the waves, and indicated its effects m driving seaward the contour lines of the shoaling since Sir John Coode'e survey.) To the chairman : It was hardly necessary to consider the banking up of shingle for the preservation of the outer kant, as concrete does not decay under water. Of course if the work was banked with shingle it would be secure. To Mr Wreathall : The work damaged at Napier was of concrete; the foundation was bad. Rubble is safer, and concrete should only be used where it is cheaper. There would be no danger, except during construction, of rubble blocks being thrown across the fairway. It was all a matter of size of blocks on the outside and end. Mr Pringle : After all our talk, I understand that Mr Bell recommends us to allow the shingle to go round, and rath* r get an extra dredge than do anything else. — The chairman that is the sum of the report. Mr Thew asked if it would be necessary to undertake the whole of the 500 ft extension at once. Could they commence it and go as far as they could with their present means, and continue it as they got more money.— Mr Bell: It would be more expensive if done piecemeal. To Mr Evans : A groin at Rock Island would stop some shingle. It would cost very little, but would do very little. Mr Evans : In the meantime we have only got £11,000, we cannot raise £33,000, and I feel perfectly satisfied that the public would not go m for another dredge. They have had quite enough of the one they have got. Mr Sullivan pressed for Mr Bell's approval of the extension parallel with the wharves, and Mr Bell repeated that the difference would be that between 30 and 45 degrees. The Board rose at 1 p.m., it being understood that the report will be discussed at the next meeting.