Wellington Graving Dock.

Progress, Volume II, Issue 4, 1 February 1907, Page 119

Wellington Graving Dock.

If the success of the Wellington graving-dock corresponds in any appreciable degree to the long struggle that preceded its authorisation, it must have a memorable career That struggle, however, may ( in view of the bright future opening out before the dock, be dismissed as a mere memory, not to be revived by any financial consideration whatever Directly, the dock may not pay Nobody expects it to do that for yeais to come But things winch are necessary and profitable do not always pay at the start, or tor borne years to come The railways, for example do not pay — the State policy is not to U t them pay anything more than three per cent on the cost of their construction Streets and roads are neither of them in the category of things that pay directly For many years no private firm could have financed the telegraph services of this country without spelling rum many times over in capital letters Yet all these things— and a whole category ot others too numerous to mention, but which will occur so readily to the mind of experience — are of the kind that are both indispensable and most profitable in all ways but the directly remunerative fashion of the account book Thus it is with a graving-dock The prestige of the greatest distributing port in New Zealand lequires one, and in the woid all things else are included The comfort of the merchant marne md the su>et\

of the King's ships are, beyond calculation, price less. Not an eye, therefore, that looks on the dock in the years to come but will lighten with pnde and pleasure. As tenders have been called for, some details of this fine work will be of interest. The length of the centre line inside the coping is to be 683 ft., and on the bottom 671 It. as measured from the face-line of the concrete retaining wall on the seaface. The breadth of entrance at the coping will be 84 ft , while 22 ft. down below high-water mark the breadth will be 80 ft. The coping level is to be 8 ft. above high water, and the sills of the entrance 32£ ft. below high-water for a width of 59 ft. The level of the finished bottom of the dock is to be 2 ft. below the sil' level along the centre of the dock, and 2 ft. 6 in at the sides Inside the coping a width of 106 ft will be provided except at the caisson stops, where it is to be 84 ft. The caissons are to be 10 ft. m thickness and be placed respectively at 10 ft , 40 ft. 190 ft., and 300 ft. from the seaward outside face of the work. The southern end of the dock will be built in se&mental form. It is proposed to construct the dock, firstly by driving temporary piles to carry the staging to command the area of the dock, pumping station culverts, and the sea wall , to clear out the area and pump the culverts from all mud and spoil down to a uniform depth and hard formation The area has already been dredged by the "Whakarin" to approximately the right depth The next step will be to enclose the area, to be covered by concrete, in temporary timber casings supported from the staging piles When each casing is cleared out a better concrete will be deposited to cover the whole bottom area A similar course will be followed for the plumbing-house and the culverts leading therefrom. On that concrete foundation will then be erected other casings so as to form the walls of the dock. The concrete placed in the casings will form the rougli first cast of the dock. When the casings are remo\ed the next step will be to fill all round the rough concrete dock, so formed with clay fillings , to pump out and staunch from anj' leaks that might exist in the pumping-house, so as to enable the boaul to erect permanent pumping machinery A coffer-dam across the mouth of the dock entrance follow. It is probable that the pumping-out of the first cast of the dock will show a considerable quantity of leakage and iuiis of water which will have to be all staunched back so as to make the first cast drj or approximately so The rough dock will by that time be in existence, and in it will be built the final face-work containing the altar steps, the caisson steps and all the work of the final dock The reclamation will then have to be completed and the cofferdam removed The present contract which has to be completed by 31st December, 1910 does not include the pumping machinery nor the floating caisson, which will be subject to subsequent contiacts.