HARBOUR WORKS

Hawke's Bay Tribune, Volume XXIV, Issue 235, 17 September 1934, Page 8

HARBOUR WORKS

BREAKWATER SCHEME Details Before the Board ENGINEER’S REPORT At to-day s meeting of the Napier Harbour Board, the engineer (Air G. W. B. Low son) submitted the following details of the works to be earned out under the proposed Breakwater development seneme, together with certain alternatives in connection therewith which present themselves lor consideration by the board. These details (states the engineer) are based upon the general outline of the proposals already adopted by the board and approved by the ratepayers, with such modifications as may be deemed necessary or advisable in order to obtain the best possible port facilities with the money available. The report goes on to state Major Works.—Taken in the order in wh*ch they will be built or carried out, the major works come under the following headings, viz. Dredging, BreakW»ter extension, erection of smaller Whan. erection of large concrete wharf, ■Pnstruction of western mole. Mihei Work*.—There are, of course, works, such as the loreshore wftli, reclamation, alterations to the (Mt at the Glasgow Whan, etc., to Moeioei, but, whilst oi importance to general scheme, theai are naturally (ptetdiary to the works enumerated (hove, and can be dealt with under jpaUftr separate contracts, or, where (MChmstances render such advisable, earned out by the Hiard itself. Predging.—At the moment, and for Em time ahead, the most urgent work be undertaken at the Breakwater is, i will be, that of dredging, for the out of which the board pur■b*Md the bucket dredger Whakarire (arlier in the year, and upon the part completion of which the commencement gf new wharf construction naturally depends. Despite the dredgeable nature of the material being encountered, excavation around the sites of the proponed wharves to so considerable a low water depth as the 35 feet required for the largest vessels visiting the Dominwa is, in this case, one of some magnitude. Realising the extent to which the early provision of extra berthage depends upon the progress made in dredging, the board is now working the Whakarire two shifts daily but, even so, it appears unlikely that the first cut along the eastern side of the smaller wharf will be completed before the end of November next, or that all the dredging around the site of the wharf will be finished before June, 1935, prior to which latter date no pde of the proposed structure may be driven, although, as will later be explained, the making of the piles and other preliminary work may be undertaken before that date. Dredging for the larger concrete wharf will follow upon completion of the dredging for the smaller wharf. BREAKWATER EXTENSION. The extension of the Breakwater is aa undertaking which may be carried out almost independently of all other waterfront activities, and thus may be commenced at an early date. The railway tracks for the large cranes have already been laid down towards the present end of the Breakwater, delivery has been given of the new three-quarter cubic yard mixer for use in the blockyard, and the latter will be transferred to its new site opposite the root of the Glasgow Wharf when the necessary track sleepers now on order come to hand. , Aa regards the plant required for the extension, the board will no doubt be prepared to hand over the two large cranes, the block trucks and all available block-making equipment to the contractor. It is rather more than doubtful, however, whether either the J.D.O. or one of our locomotives could be spared for the duration of the contract. Possibly one or both of these unite might be hired out to the contractor as required. The necessary plans and specifications for the Breakwater extension contract should be ready about the end of the present month, and, in calling tenders, 1 suggest that ample time (say until the November meeting of the board) be given in order to permit intending contractors carrying out the necessary investigations regarding suitable stone, roarser aggregate, etc. Similarly, in view of the delay likely to be caused in the earlier stages of construction prior to the consolidation of the rubble foundation, 1 should fix tho contract period at three years. Smaller Wharf—ln dealing with the question of the smaller wharf to be erected under the loan proposals, the board naturally has to consider the respective requirements of shipping, cargo handling, rail traffic and motor transport, and to do so, must first realise clearly the main functions of the wharf. This wharf is, primarily, an export wharf for overseas shipping, and, as such, must be able to cope with ft large—probably, on occasion, even the greater—portion of the meat and woof passing out through the port. This aspect of the matter has been fully discussed between yourself and the board’s officials, and has also been brought to the notice of the luigincer-lu-Uhief of the Public Works Department, tho unanimous opinion being that a thoroughly efficient wharf, capable ot accommodating the largest vessels visiting New Zeaiaud, and suited to both rail and lorry traffic, should be constructed. 1 therefore beg to recommend the erection of a reinforced concrete wharf. 750 feet in length and 81f feet in width, carrying five lines of railwav track (the centre line feeding both sides of the wharf) with provision thereon for modern electric cranes on each side, and with dredging carried out alongside to a low water depth ot 35 feet. To enable this recommendation to be effected at a reasonable cost, and to provide a structure ot sufficient strength aud rigidity to take the largest typed overseas vessel I advise the erection of a vliari of the design shown on plau No. K W submitted herewith. This type oi structure is now largely adopted at Home and ie more or less new to the Dominion, but it quite supersedes the hitherto standard type ot reinforced concrete wharf, besides being more rigid and less costly to build. Including the necessary spring piling, the whart proposed would cost in the neighbourhood of £60,000. To meet the additional amount involved m widening and lengthening the wharf beyond the dimensions of the timber structure originally eontemplated, the sum of £16,000 reserved to< the provision of

electric cranes on the large wharf may with justification be transierred to this more important work, and the requisite amount made up as follows, viz.: Amount allocated tor timber £ whart 20,000 Amount transferred from electric cranes 16,000 Portion of Unemployment Board grant 25,000 Total £61,000 LARGE CONCRETE WHARF. Dealing next with the large concrete wharf, your officers consider that, with the money available, the general utility type ot structure is that best suited to tne needs of the port. This means that the wharf deck will be level throughout, that wide roadways for lorry traffic will be allowed on each side of the shells, and that two lines of railway track will be provided on each side ol the structure. Due provision will also be made for electric cranes. As regards wharf appliances, however, it would seem good policy to deter calling tenders for the erection of the transit sheds and the supply and delivery of the wharf cranes and other cargo handling gear until all other contracts are let. The board will then be in a position to determine the most satisfactory type of shed and the number of cranes and other cargo handling appliances that can bo built or installed with the funds available. Incidentally, it may be found advisable, instead of placing lour electric cranes on the larger wharf; to place one crane ou each side of both the proposed new wharves. The cranes on both the latter are. as a matter of lact, interchangeable, the track gauge being the same on both structures. As in the ease ot the smaller wharf, pile-driving cannot be commenced until the necessary dredging is completed (in this instance not until July, 1936), but the contract for the erection of the wharf may be let and many of the piles made several months before that date. A period of two years should be allowed in which to build this wharf.

Western Mole.—Coming now to ths consideration of the western mole, it will be remembered that the smaller whart above referred to is intended, and is eminently suitable for dealing with the lighterage traffic until such time as the latter gives place to overseas shipping at the wharves. The need for the western mole is not thus so imperative, and as, from the point of protection for coastal and overseas shipping.from a lee shore, its value may possibly prove of no great consequence, 1 should recommend deferring its construction for the meantime at any rate.

CARRYING OUT MAJOR WORKS

As regards the carrying out of the major works, either one or other of the tollowing alternatives may be adopted;—

(1) The extension of the Breakwater and the erection ot the two wharves may be let in one contract. (2) One contract may be let for the extension of tho Breakwater and another let for the erection of the two wharves.

(3) Separate contracts may be let for these three major works.

In my opinion, and in that of the Engineer-in-Chief of the Public Works Department, the last procedure is the correct one to follow, as, among other things, it enables the extension of the Breakwater and tho erection of the smaller wharf to be commenced at earlier dates than would otherwise be possible. The board, moreover, would not place itself so much at the mercy of one contractor, whilst, by letting the works under separate contracts, each contractor is better able personally to supervise and carry out his own work, which, in each case, is of some magnitude. Furthermore, competition is likely to be keener on separate contracts, and tenders consequently lower. Reclamation Wall. —This work, which includes the wharf abutments, will, in part at any rate, necessarily have to be completed at a very early date, and I recommend that the material now being secured from tho root of the Breakwater be forthwith utilised for building the rubble backing, and that the reinforced concrete facing, which is designed on the "De Muralt” principle, be later laid by contract when the rubble has consolidated. Prior to the slabbing being laid, the wall will present rather an unsightly appearance, but the completed works will be quite neat and should be secured for a comparatively modest expenditure.

Reclamation around the waterfront will be effected from spoil obtained from excavation adjacent thereto, there being as a result of the earthquake upheaval more than enough material for the purpose, leaving the surplus spoil to be taken either to the foreshore fronting Hardinge road or to the North Pond Tendering for reclamation should be comparatively keen.

EXECUTION OF OTHER WORKS.

Works now in progress, or contemplated within the next lew months, are:—

(a) Cutting through the root of the Breakwater, and grading down from the railway yard to the smaller wharf.

(b) Laying the sidings in the new yard whenever the sleepers come to hand. (c) Effecting alterations to the root of the Glasgow Wharf in order to connect same to the new railway system. (d) Removing the old approach whrrf, which will no longer be required. (e) Railway yard and wharf approach illumination.

Items (c) and (e) will form the subjects of separate reports at au eat ly date and need not be considered further at the moment.

General. —There are, of course, other matters such as wharf lighting, water supply, reading, etc. to attend to, but such can be dealt with as the major works proceed. The board will, however, at no distant date, require to enter into some agreement with the Napier Borough Council as to the final grading ami location of the Breakwater road, which will otherwise, when the harbour works are completed, be many feet above the level of the wharves and adjoining foreshore and so detrimentally affect vehicular traffic to and from the wharves.