HARBOUR EXTENSION.

Taranaki Daily News, Volume XLVII, Issue 81870, 20 October 1906, Page 3

HARBOUR EXTENSION.

- m ——— ' THE ENGINEER'S REPORT. ECONOMICAL AND SATISFACTORY WORK. The New Plymouth Harbour Board's consulting engineer. Mr V. W. Marchant, M.1.C.E., reported to Fiiday's meeting of the Board :—Breakwater. —Good progress has been made with the extension since my last visit, and everything in connection with the work is being carried on satisfactory. 1 have gone 1 fully into working details with the e foreman and poinied out any items " where I thought improvement could " be made, lam informed that some 3 few months ago as heavy seas ran " here as have ever been experienced. • Beyond live, displacement of a few 1 blocks at the unfinished end of the ' work no damage whatever was done - nor did the completed work settle even '' a quarter of an inch. The wave'l breaker nu>,H of course, be maintainr rd with the pick of the largest rub- : bio until it attains its final slope of [ stability. The extension has greatly ■ sheltered shipping at the wharf. ' Dredging: I" have examined the working power of the dredge with the new suction head, and cannot say I think it has any advantage over the old one. The only way in which a ' really definite opinion could be form- ' ed would be to substitute a week's ' trial of each under similar conditions and carefully note results. These ; experiments are always worth trying, otherwise no improvement in any di- • rcction would ever be- made. It is • apparent to me that a good deal of ' mud is acumulating in the harbour. ' This rc-uhs from a long period of pump-dredging whereby the sand is ■ sorted out, leaving the intermixed ' mud behind. It will be found necessary before long to clear out this 1 mud by means of the grab, as we had « to do some three years or so ago. ' About the dredge there are a few points where 1 think improvements ' is possible in her details'. These I 1 have suggested to the foreman, who 1 can effect them when she is next out ; out of repair. ; Wharf Extension: The question •■ f 1 a transhipment shed has been looked t into, and I called on the railway stai.ioumaster to discuss matters with ' him from his point of view. Before - anything is finally settled about the i structure, I suggest that an outline j plan should be prepared showing the 1 location of the shed to the railway j Department, so as to avoid any flic- 1 ,tion or dispute subsequently. " ' Mr Marchant verbally reported on < the stability of the breakwater exten- J sion and flatly denied the statements < made that dredging the inner liar- t bour to a depth of 25ft that would t at all endanger the wall. He did t know who had made such a state- < meat. HOSTILE CRITICISM. MR. MARCHANT TAKES THE FLOOR. Mr Maxwell followed quickly, stat- ; ing that he was one of those who ' made the statement referred to. He •' had no doubt the wall was safe en- s ough as long as the present depth ' was maintained, but he very much £ questioned whether it would be safe ' with the basin dredged for deep-sea < vessels. He would like to ask Mr ' Marchant whether, when in 1900 he ' recommended the addition of this 1000 f feet of wall, and the dredging of 100 '_ acres to a depth of 25 feet, he in- ' tended to build on. the sand, or on I the natural sea bottom; whether the i.75 P p r foot estimate was given 'n ' the understanding that the rubble il would go approximately to the natura bottom, or merely form a cap to the sand bank, which kept forming ' ahead of the breakwater? - Mr Marchant said the idea origin- ' ally was to build the wall in 20 feet of ' wat'T, at an estimated cost of £75 a foot. The action of the- sand in banking ahead of the work as it pro- J cccdcd had considerably cheapened the cost and the system of construction had cheapened it fltill more. r Mr Maxwell: Was your recommendation to the Board based on 'he ', idea of a breakwater formed on the v bottom, or on the sand ? Mr Marhcant: We reckoned on v building upon the natural sca-bot-i ', torn. v Mr Maxwell; As borne out' by your ' estimate ? l Mr Marchant: Quite so, "but why '. not effect a saving? The Board should be satisfied with a saving of about I a third of the cost. My point is this— , ihat_the sand is just as good as small ' rubble. It lies ten feet below !.ow r water mark, wliicn proved the waves s had no disturbing power below Uiai f depth; that was absolute logic. But tor the action ot the sea leaving tins J heavy sand, they would have to use , rtyiu. it was a good job for the v Board that the sand did lie there, foi u was as good as stone absolutely incompressible, and hard as the floor. "The proot ot the pudding was in t.ie . eating, ' however, and it was gratify- , ing to notice that mere had not been ' r any subsidence or settling down ,1 j the work in ilie past 12 months or more. 'We are saving. 'he said, "by reason of the coarse'sand drift, , and what i-, the use oi our securing c away what the se a leaves as permau- ( ent as the sione iiseit i \ou see . the pointr" ' Mr Maxwell: Q u i le; on l y 1 dis- , agree with it, as the deduction 1 is not according to fact. 1 bel.eve | t.iat if the harhour is maintained at , its present deptn it will do all 1 hoped < tor or anticipated, but it ;s not 111 , accordance uita your leeommenda- 1 , Won A sand spu i- bring built 1 . up and the crown of it n being pru- 1 ( oxicd l,y lubb.'., - i.Ui Ma-jiwe/, . . diew a sketch to illustrate lu» mean- t ing, mat the sand was tunning a . very gradually sloped mourn ain under water, and the jubde was being , placed upon n muca the same as a '. >nia,l block on i,,p 0 | an inverted , millVpan.) 11 by dredging the extreme ol this mound were interiered I with there must be a subsidence ol . sand to fill the hole, and tile "cap '. would suii-ly follow.

I Mr Marcham considered Mr Max well not putting the ca-e fanly. The natural depth of the water wa= about twenty ie< t. There was about : ien feet .if -and below tlie rubble. Mr Maxwell-. Mute Mr Maieaani: Perhaps twelve j Mr Maxwell: M"n Mr Maieliam protested. Mr Maxwell said he had proof that there had been more than that. He a-ked, What depth arc we getting on top of the sand ? Mr Marehant said th.it the -and was about ij or t 4 fee, below lowwater mark, and the rubbje was eaired to three f,.,. t . lb , u . UjK %val< .,. mark;. Mr Max'.-.ell: Would vou be -urprised to hear—and the Hauntem can be borne out—that the .--and wawithin three feet of the surface at certain period- in the progress of 'he work ? Mr Marehant (with vigour): f don't believe a word of it. The stone is dropped into the sand, and form- an "bMrucoon to the (uneal, which setup a swiil and a soair. and the st,,ne fink- lo a depth of ten feet or mere. Mr Maxwell but 1 ran prove it is so. Mr Manliam preferred to believe the evidence of his own eyes. He iiad uk-'-n soundings on several cc..«(>ns. and had never found 'c - . than ten feet. . Mr Maxv.-l! called f : , r ,;„■ harbourmaster-, chares showing- depths j,. . various |hl na of the haibmir. L Tiie chairman took the oppoitun- . i!y to remark that the soundingi must have been wrong rocdillv, for the Takapun.i. drawing i -ft' oin.. rrm- in a' l"w natc. over pkovs that Mr Marehant informed ilie |;,:a:V there wa- no al,c;nalive m> hod ~| .' consiMiciing die wall with the food i at their disposal. l-jiher a rubbl ■ mound alone, or a mound capped • v ith concrete must be const rueted. - and a- lac heave sea- ~< the past yea. ■ had fated to disturb the wok notli - dig (ver would. There was no t>a ( -on to iliink that dredging to am . depth v."uld di-tnrb it'. Mr Maxwell asked: If my plan i i ci.rreci. and this i s -imply.a break . water on the crown of a fiandsplt- an' i i'lis spit i- reduced hv anv mo.tn--1 will it be unsafe ? Mr Marehant •..,;■, j, would be saf 1 tin'dis the d:;-:'!:-' were taken to ■ he lo the wall; and. at any rate ." the plan- did not provide for 25ft 0 r -eel.., : „ .he vail. Jijr Maxwell mentioned that cm ;

'previous occasion dredging a channel in the inner harbor had affected the level of the sand at the wallbreaker, and argmd from this that dredging would do the same again. Mr Marchant said that if there were any alteiation in the slope of the stone apt on, more stone would heed to be tipped over. Mr Maxwell: You admit that your original plan was to place the rubble on the bottom, and that the dredging of the 12ft channel affected the breakwater ■ Mr Marchant: No, the sand. Mr Maxwell: Well, the sand. And if 'you have only three or four, feet of rubble, that sand bank and breakwater are going to be unsafe. Mr Marchant: I don't know where you got vour information from, but 1 swear it's all wiong. 1 swear it's untrue. And 1 invite the Board, or any mcmlur of ihc Beard, to come down and sound the depth with mc ; and if 1 don't find ten feet of water, or more, well—well, I'll never come here again.'' Mr Marchant compared any attempt to dredge away this sand with Mrs Malaprop's mop. against the Atlantic Ocean. The constant swirl and turmoil at the end of the work would defeat the best dredge over invented. Mi Maxwell. Did you foresee this shifting of the sand ? Mr Marchant said he would have been foolish to depend on it. Argument returned to the depth of water above the sandspit when the rubble was put over, Mr Maxwell again asserting the depth was only a few feef. "I assert it positively,'' he said, "for I know." • The Chairman: Have you been out there? Mr Marchant: Have you been out in a boat, or what? It's not safe to assert on evidence in these things, you know Mr Maxwell said he could on one occasion have tucked up his trousers and walked out on the sand bank where the stone was to be dumped. The chairman reminded Mr Maxwell that the stone was thrown ou; fully 50 or Co feet ahead of the completed work, and sank considerably after being thrown in. The spot selected for Mr Maxwell's walk might have been sand lying on the top of the rubble. The engineer reminded Mr Maxwell that even if this were the case —and he did not believe it was—the action of the sea, tho constant swirland scour, would have the effect of lowering the stone into the sand until the action 0 fthe waves could no longer affect it. Mr Maxwell explained that the discussion was the outcom? of a statement made by Mr Newon King at a Chamber of Commerce meeting that the engineer had not foreseen this action of the sand, and 'bat be was not the only ono who had fallen into the error. A statement like that made by a leading man in New Plymouth caught the public eye 1 . Mr Marchant: Where was the error? Mr Maxwell: Mr King said there was an error —— Mr Marchant: I dont care what anyone says. All these points were dealt with by Mr Napier Bell and • rny-elf. We know all about tinsand. But to tell how much ? How ctou'td anyUie estimate how much sand there would be left under 'h.7 rubble. Contingencies might hav occurred, so that the "sand would have scoured away as fast as the work proceeded. We estimated building the wafl in 20ft of wator at low tide but now it's going in lofl, and the odier loft is on hard incom pressib'.o sand. Mr Maxwell was interrupting with apparent warmth, when Mr Marchant asserted himself: "LET ME SPEAK'' to the Board. To put rubble instead of sand would be absurd. Besides, you cou'ldn't dredge .it—no dredge ever invented would shift it as fast as it collects. I have no knowledge of the- i.ndcr-cutrcnt of this discussion, and I don't want to be mixed up in it. But Ido say the Board has no reason to complain. Mr Price paid the present work was j n<t on the migina'l plan. Mr Marchant: Well, if the sea lik:s o shoal the water for us, why should ( we complain. The first plan was ( to run out a staging from the old ( wai'i and tip the rubble from that on | 1:1 the natural sea-bottom. That would doubtless have been done if ( the Board had had plenty of money , to spend, but as the work was being , carried out with money that came in diiblets—ordinary revenue —that plan 1 was not possible. So Mr Napiet Bell advised a irial of this system, ( t'n the understanding that it would not be cemtinued unless it prbved satisfactory. But by the system of , erecting staging the Board would have spent all the money so far ex pended and got nothing done yet ] but preliminary work— ! the I stajrin,ij| would have absorbed all the funds. Mr Price was satisfied that as the work had slood a year's rough weather it would never shift. Mr MaxwcM said lie had no desire to appear antagonistic, or to doubt Mr Marchant, but the question raised had caused an uncomfortable feeling in the country. He had had certain information ,and naturallv wanted to know how far it was correct. He was satisfied now that the engineer had known of the modification of the system of construction, , and was convinced that he, as an engineer of consedarble reputation, recommended the change. But the Board had not known of it. (Hear, hear, and dissent.) It had been made to appear that the Board was saving money by doing the original work at less cost, but the members had never been told the sand drift had anything to do with it. The members had not known the rubble [ was being dumped in six feet of water. Mr Connett essayed a word, when Ml Maxwell also tried 1.1 resume his rcmaiks. The chairman mildlv re-

marked, "Excuse me. Mr Maxwell has had tho flour for'half an hour l>m 1 can't get in a word of self-do-frncc. Is iliat fair to tin' chairman? Silence restored, Mr Conneit averted thai lie had repeatedly stated the saving in ra-i was being effected by the banking of the sand.

Mr King endorsed these remarks. He was glad of the discussion, and of 'he cnjjineiM'.i presence. On the one hand they had the consulting- engineer, who was cmtus.cd with the budding of the harbour for oceangoing steamers, and a gentleman f wide experience in these matters; on the uth.r hand, Mr Maxwell. There was a clear issue lor the ratepayers lo decide between the two. Mr Ward supported the system of construction. Mr McLean asked lie- engineer if »UP|).-smn -lone we,,, tq.pej „„ to the bank in .six Ic-.i o| w.i.er. llial : '■'»'■ would .-ink unti'i U >ond "leach "! die .va scour. Mr Marc-ham: That's just what J Air i'lion, on ; M r Matcliant denicll'a, He- -and varies a, tones Mr Man-ham : X,,. 1 don't. Mr Hornby warned h> know if tluie was ;, ii-k in the present system ••I' con-.in.ieii.in. Mr Marcliani could sec none, nor ■ could he s-e any nu-e, way of doing Ihe work. !.\eiy -hilling spent now went mio ihe work. Theie was no ■ doubt of ics stability, and if there ■ was lie.' s'igliics; .settlement of rubbl" ■ more st> ne could be tipped over Mr Hire- said Ilia! not a single member doubted the stability of the - stiuciuro at pro-em, bin sonic doubt , <"1 'ls safety in futuie deep sea diedging for bigger steamers.'' The Chairman: Then yo„ au . |,,J,. - ing forward to oceangoing steamers r .v'.ling hue, Mr Mine? (Lnuginer.) Mr lline assented'. I Then the Hoard proceeded to oilier . busieo-s,