DRAINAGE BOARD.

Otago Daily Times, Issue 12607, 10 March 1903, Page 2

DRAINAGE BOARD.

FREDERICK STREET SEWER. A special meeting of tho Dunodin District Drainage Board was held yesterday afternoon to consider the report from the consulting engineers (Messrs A. E. Cutler, Leslie 11. Reynolds, and John Rogers) on the Frederick street sower extension. There woro present Messrs It. Glendinitig (chairman), J. Hazlett, J. Gore, W. Burnett, J. H. Hancock, and Dr Coughtroy. The report was read'as follows:— ' Town Hall Chambers, Dunediii, N.Z., Ith March, 1903. Frederick Street Sewer Extension. S. H. Mirams, Esq., secretary Dunedin Drainage and Sewerage BoardSir,—ln compliauco with the resolution of your hoard, passed at a meeting held on the 12th February last, " that the plans in quostion be submitted to the three consulting engineers for their report," and conveycd to us in your letter of the 2nd inst., we have now the honour to advise you thereon as follows: — The drainage engineer has supplied to us: — (1) Tho original signod specification with form of tender and schedule. (2) One signed bond with two schedules attached, and tho printed general conditions of contract. (3) " Drawing No. 1, referred to in contract No. 6," showing longitudinal section of natural surface and invert level of proposed sower, and a cross section of !the sevrfer to be constructed with " reinforced" concreto invert, sides nud covering. (4) "Drawing No. 2 (B), referred to in contract No. 6," showing cross section of sewer with roinforced concrcte invert, brick walls, . and reinforced concrete covering. Wo liavo inspected tho site over which the sewer would ho extended, and find that for a length of from, iour to five chains. the bottom consists of soft yielding mud and silt to a- depth of about Bft. This will necessitate spccjal attention in construction, and' whereas tho schedule of quantities provides for 150 ft of piles, the specification does not define the manner in which the piling is to bo applied to ensure tho stability of the work. We liavo carefully considered tho moat suitable design under tho existing conditions, and aro of opinion that that represented by "Drawing No. 1," providing for the construction of the work inrcinforccd concrete," would he impracticable, and the work unstable and unsuitable for tho existing conditions. Wo could not, therefore, recommend the adoption of this design. A sewor represented by ".Drawing No. 2 (B),"' providing for the construction of The work by reinforced concrete invert with blue stono dis-. placers, walls of Sin brickwork,' and covcred with ieinforccd concrete slabs, would bo much more substantial and pcrmaneut. • Town Hall Chambers. If confined to the two designs submitted for, our opinion, we consider that the construction represented by " Drawing. No. 2 (B)" is unquestionably tho ono wo would advise you to adopt. We have, however, to bring before your attention the expediency of increasing the capacity of the sewer, as, from our calculations, v:e consider the discharge of the drain as designed insufficient for requirements. We have therefore considered it.desirabl: to remodel tho design, thereby increasing the stability and tho capacity of discharge about 80 per cent. Tho plan forwarded herewith represents flio general oross section which wo have to recommend, and would necessitate only slight alterations to the timber at present in position, Tho supervising engineer would require to exercise discretion in carrying out tho foundation works as the special conditions might justify. The cost of the work as recommended by us will bo a slight increase over the original design, and will be approximately £2200; but we consider tho additional discharging capacity and stability more than warrants the additional outlay which would lie involved. In conclusion, wo havo to recommend that tho sewer be extended in nccordanco with tho design wo submit herewith. (Signed) A. E. Cotler. Leslie H, Reynolds. John Booem. The following report was read from Mr J. T. Noble Anderson, drainage engineer: — Olh March, 1903. Tho Secretary, tho board. Sir,—l havo the honour to deal with the report you handed mo on Friday afternoon. This has not boon formally referred to me, but I think my duly in the mattor is plainly to deal with it so that my views as its professional adviser may bo before the board when it comes lip for consideration. First!—l have calculatcd tho .strength of tho accompanying design; and find it wanting, Tho invert must crack open us soon as tho stoam roller passes, over it, and the cover must burst so soon as tho incipient rusting of the railway rails, with which it is reinforcpd, has continued long enough to swell it. For designing and constructing a similarly indeterminate and antiquated reinforcement throe (3) enginocrs at the last Paris Exhibition wero tried and actually convicted of manslaughter. Second.—Tho invert shown, if built, must increase tho' troublo whioh at present arises from silting up, and would cauae at least three times as mnclrdeposit in the sewer. This is probably the Tcasbn why this design has been mado so much larger in discharging capacity than tlie sewers which it is to accommodate. But the fact must not be forgoten that no increase of size will mako a sowar large enough which is so designed that it must inevitably silt up. In 1886 I was employed in Larno (Ireland) to survey a similar sewer of about-similar dimensions and conditions which had become inoperative, and was subsequently replaced by an egg-shaped sewer, On digging it out I found it completely.blocked with silt. /Third.—The life' of this sower must inevitably bo brief. As above stated, old steel rails as those must be cannot 1 bo. protected 'sufficiently to check their incipient rusting, and in ordinary fi to 1 concrete, their swelling duo to rust, rapidly bursts the surrounding concrete. Again, the inevitable Assuring of the invert mentioned above, which has been left without tho proper reinforcement, must cause the water to eseapo and flow beneath the sewer. Hero tho broken stones will not suffice to prevent the fretting away of cavitie.i in tho .clay beneath; By some inversion it will bo noticed that, these broken stones have been placed below instead of in the usual and proper place —abovo the wooden deck. Fourth.—lf this.sower could bo maintained ill a perfectly clean condition it would bo capable of carrying more than twjee tho maximum discharge which careful measurements of tho flow of water havo shown as tho total discharge of the .sewers whioh supply it. This is to say. tho discharge would lie double what is needed. Fifth.—Tho design is extravagant in proportion to its strength. In point of fact, it is not only interior, as I have pointed out, to tho original oviform sewer- laid down' by Mr Mirams in 1877 in being deficient ill self-cleans-ing proportions, but it is altogether weaker. Tc bring it up to similar strength, retaining its salient features of railway rails, brick sides and reinforced bottom, tho design must bo altered to cost £3050, na against £2000, which tho o'.d oviform sewer,would cost. I avoid criticising minor errors in the design. ... With your permission, I proposo to cany out contract No. G for this sewer in.accordance with the design I recommended with the concreto sides, . I liavo givei you tho most earnest guarantee in iny power of the efficiency of this design by .practically stakiiig my professional reputation agauist the late Works Committee's views pn this section. At the samo time, lest this fact should not have been appreciated as it deserves, I am prepared to givo you a monetary guarantee, in which I will be supported by a gentleman of tho highest professional standing in tho engineering'world, that I shall , at my own cost repair any doficicncy which may arise under a practical test applied after the contractor's period of maintenance has expired. The course I recommend is that I instruct tho contractor to proceed under Schelude A, and this will pave'a considerable expenditure. , Writing to the socrolary on the 6th March, the drainage engineer. stated that lie understood tho consulting engineers' report would be submitted to a meeting of the board on Monday. Ho continued: " I wish you to bo po! good as to inform the board that I told these gentlemen last Tuesday forenoon that unless tlioy could givo mo thoir views on' this matter on or before Thursday their report would be valueless so far as the contract is concerned, as I could not hold the contractor's hands any. longer, and intended that ho should in any ovent start work this morning. I sent ,him notice first thing this morning to proceed with all haste.—(Signod) J. T. Noble Anderson." Dr Coughtrey thought that, as cußtodiana of tho public purse, the board were bound to

oxercise in a matter of this sort whatever degree of common sense and intelligence God had endowod them with. He bad given the matter a largo amount of consideration as a representative of the people, and 1 ill reading the report of the consulting engineers the first thing he noticed was that those gentlemen had gone beyond what they \vei|e asked to do, and that if the board were to adopt the proposed design it would be inferior as a scientifio sewer to the design by Mr Anderson. It was inferior in point of strength. It did not economically utilise the materials in accordance with modern practice, and the character of the invert in which the sowage flowed, taking tho average amount likely to flow, was not such as would make it a serviceable sewer. Then tho expense the community would bo put to would he £400,000 for the whole schema it such extravagances were allowed. Later on the Frederick,street sewer would only deal with storm water. At present it ministered to less than SO houses, when tho whole scheme was in force thore would be 9700 houses in tho district to bo dealt with, and if all parts of the district were to bo dealt with in such an oxponaivo way it would mean an onormous sum. Ho could now understand how the Sydney sewerage schemo had cost such » large sum, and how that schemo when submitted to the Home authorities was found to cost so much more per head than systems elsewhere —systems which on the Continent ran from £1 7s per head of population to fH in London and to £8 in Sydney. There were many defects that he could discuss if he wished to prolong the meeting, but he thought the ratepayers were tired of playing tho game of the old' man and donkoy. The motion he would move was—"That after living discussed and considered tho report of the three reporting engineers on the Frederick street sewer and our export's reply theroto, the board direct their engineer to carry out that design which he thinks will best conserve the intorests of" tho ratepayers." Mr Hazlett seconded the motion. Tlw matter lwd been referred to the onsincor-, who, instead of giving the. board their opinion about it, had made an entirely new plan. Tho Chairman:' Which they were not asked to do. Mr ITazlott agreed that they were not askod to do that. Tho hoard mu«t have some finality in tho matter—(The Chairman: "Hear, hear");—and he would say at ouce flint- h ( . Wi i S i n favour of Dr Coughtrey's u.otion. Mr lloro said it was with a considerable amount of relief that he had listened to the report of the consulting ongineers. They could not ignoro tho faot that for some time back the Works Committee had, been on their trial. They had been aceuscd of spending money unnecessarily, nnd very unworthy motives had been imputed to them for tho course they proposed should be taken. Monitors need not deny that. It was the common talk of tho man in the street that two of the members had an interest in accepting the higher tender: lie could prove' that the statement had l>cen made. It was gratifying to him, then, to know that tho committco hid been exonerated, and that tho fault, if there' was any fault at till, was thtf they had nccopted a tender for the work that was not strong onough. Ho was not going to' discuss tho ongineering merits of the sewer: he loft that to the engineers. They had three ongineerii who were presumed to lie competont men—they were leading men in their profession, at all ovents,—and, he believed, thoy wero equal to any others who could have been got in the colony, and theso men had decided that tho sewer which Mr Anderson wanted to construot was not strong enough. That was tho sewer that the Works Committee had condemned hb being not sufficiently otrong. The engineers had not designed a new sewer. If thev had dono so tlioy would have designed a better one. They had siiripljv strengthened -Mr Anderson's weak plan—thoy had addod to the strength of it. Dr Coughtrey said it was weaker. Surely, if thoy put more material into a work and made a wall thicker—l2in instead of 4in,—it would make it stronger; In this case the increase was to Sin from 4in and tho top to 6in from 2in. That was the difference between Mr Anderson's sewer and the sower tho engineers rccommcnded should be adopted. There was one remark Mr Anderson made: !:o said that 40!b rails would rust, and that thoy could not bo protoctod. If so, Jiow much more would o,nglo steel rust in 4in of concrete whore there was only lin of coneroto on each side of it to protcct it from tho water. By putting ooncroto on" to the soft mud bottom they wore bound' to loso nn inch or t'lVO of it. The mud would destroy the cement and it would bo littl6 more than shingle. 'Ho would vote ngainst .the motion. So could not conscientiously vote for a thing that ho believed would collapse or that would not stand. It might stand where there was no traffic, but directly the vibration camo on tho looso uand it would be shaken to pieces. Thoy could not construct a sewer nearly tho, third of a mile long for £1100, and nobody olse could do it cither. It took money to build theso sewers, and £1100 -would not build tho third of a mile of a sewor. Personally, he did not care a straw how tho' matter wont. Ho was not interested one iota what way it won't; but while he was a. number "of ° the board, representing the ratepayers, he would not vote for throwing money away, nnd he. believed it would be simply throwing money into tho bay to nut a lot of concreto into a mudbank where in one ,place there was nothing but the soft cilt Bft deep. It would be the height of madness. He quite understood what Mr Anderson would do: ho would use piles or some other means for strengthening, at the cost, perhaps, of hundreds of pounds. \ Mr Burnett would also vote against tho motion. They had called in three engineers, and ho understood they were going to take their advice. The engineers wero tlireo competent men. and, as a representative, of the ratepayers, ho would follow tlroir advice. The Chairman: Have you anything to say, Mr Hancock? Mr Hancock: I liavo nothing to say. Dr Coughtrey, in reply, said thoy had only to remember tho circumstances under which tho engineers wero appointed. Thoy wore appointed when the board was under the baneful influence of tho old committee. Mr Gore: I rise to a point of order. That is not proper language, and if new matter is to be introduced I shall claim tho right to reply to it. Tho Chairman: I think Mr Goro is right. Dr Coughtrey: Very well, sir. All I desire to state is that a greater amount of material may be used, but if it is usod unskilfully or improperly it may not contribute to tho strength of the structure. I nm very pleased that Mr Burnett has attended thifl meeting and given liis reasons for voting. Tho motion was carried by 4- votfß to 2.