THE HARBOUR

Patea Mail, Volume VIII, Issue 997, 14 February 1883, Page 2

THE HARBOUR

report from mr:john

: THOMSON. Tho : following was read at the last meeting of the Harbour Board ! ■ . ' Eatea; Hax-bour. Waitara, Pcb; 10, 1883. To the Chairman of the / Harbour Board,- Patea :

Sir,— ln accordance with instructions received ffronr you on behalf of the Patea Harbour Board, Uhav.o now the honour to lay before you-ithe following report oh the present state of the river, and what works are most Rujtablo.for improving the entrance at tlie least possible cost. I need not enter particularly into a description of what lias been done in the past'.* as-it is fully’ explained' inr niy former reports hj but I may femindyou that the prevailing K.W. weather .causes? the sand and sliingle .to travel down- the coast towards Whcnuakura. Formerly the river met this drift at the Heads, and was deflected .in, the, same direction till it enmo to the old boulder bank, which stopped its southerly course and caused it to cut its way through the coast drift,' then known as tiro samlspit, forming llio bar. The S.E. guide pier, when built,’ took the place of the boulder bank, and in moderate weather the river now runs directly out to sea, perpendicular to the const lino, although the drift still tends to. turn it to tlie southward. The reason of this very favourable result is the groat quantity of tidal,water which;: flows over

tho bar, and which is quite sufficient to keep (ho entrance good, even in tho driest summer. It is only after severe and continuous North-westerly weather, when the sand drift is very; much increased that tho current is unable to clear away tho sand, which consequently encroaches on the river till at last it overlaps tho end of the present pier. The sand spit thus formed renders the entrance very dangerous and; owing to tho heavy sea it is impossible to come into the river. without running a; great risk of being dashed against the concrete blocks which lie to leeward on the end of the breakwater, as there is tm protection of any kind on the weather or N.W, side, and the channel is narrow at low water. During the Winter at New Plymouth breakwater, it was only possible to work 19 days in three months. Dad weather of this kind is a rare .occurrence nnd sufficiently accounts for ' the state of tho bar a few months ago ; which seems to have created quite a panic in the district. I stated publicly at the time, that when the weather moderated the entrance would be as good as, ever, and this was found to be the case in a few days. The most important questions for the district are as follows Is the river capable of improvement ? and if so, what is the smallest sum likely to effect any appreciable change for the better? Lastly, Will it pay the residents

in tlie district to tax themselves to a very small extent, in order to pay interest on a sum sufficient to carry on the work ? With regard to the capacity for improvement, I shall quote Sir John Coode, who examined the river personally a-few years ago. In August, 1880, he writes — “ I confess to some feeling of disappointment that a definite decision has not been arrived at, to proceed with the outer and more extensive works, ... The

success, however, which has attended the undertaking so far may, and I trust will, induce the.authorities to sanction the construction of the east and west piers. .

Unless the money be at hand for doing the work properly-the matter had better remain in. abeyance.” In March, 1882, he gaya—f I am sorry that the works at Patea have been suspended at 'such an early stage, for I am sure the conditions there are such as would fully justify* the outlay X recommended. However, we must’hope they will be resumed ere long.” After this very flattering testimony from the foremost marine engineer of the day ; it is needless to say much more, but I may point out that the most favourable thing in connection with the river is the large tidal flow, caused by the absence of rapids, shingle, or serious obstructions in the upper reaches. This and the other natural features in connection therewith cpmbine to render it improvable at a comparatively small cost. This is exemplified by works recently executed, the sum spent on the pier being about thirteen thousand pounds. The river was almost impassable before, but now, in moderate weather, the entrance is Very good for a suitable steamer, somewhat like the old Patea, with twin screws. Unfortunately the tendency is to employ steamers just a size too largo for the port they trade to. The delays and accidents caused by this practice, however, are always ascribed to the bad state of the harbour.

Prop© ss ecl IN’e>y Works. From tlic description of the entrance given above it is evident that the current in the river is strong enough to keep the sand spit in check in moderately rough weather, and that it is only a continuance of heavy N.W. weather that enables the drift along the coast. to overcome the scouring power of the water. From this it follows that in order to preserve the entrance in a safe condition it is necessary to reproduce, in rough weather, by artificial means similar conditions to those that exist in fine, when the entrance is good. This can be done by building on the N.W. or weather side of the river a breakwater on the lines laid down by Sir John Goode. If this were done it would cut off the heavy breakers, and produce a fine sheltered entrance. Vessels then coming in would be in safety'"when they got to leeward, of the work, Jong before they came to the present pier, where the water would be comparatively smooth.The channel ' would also' become much; wider on account of the flow of sand being; checked, so that when the spit, which is now : inside the site of the proposed work, was washed away it would not reform. The drift would accumulate on the outer; side of the new work, and after the beach bad risen a certain height the sand would continue its course down the coast by passing round the end of the pier in deep; water where it would cause no incon-; venience. The shortest length’6f : this pier that it would be advisable to commence with, would be the first five hundred feet beginning at the cliff.. This would shelter the end of the present.pier from the worst seas and the low-water channel would widen considerably;: The ; difficulty in beginning a work of this class is the first outlay on proper plant, for the work must be of a permanent and massive character, and even a few hundred feet would require almost as much plant, as would be required for the execution; of the entire work. The cost of plant including buildings at Oamaru breakwater was, I believe, about ten thousand; pounds, which is very moderate indeed fox*: a work of that class; that at New Ply-* mouth cost much-inbre, and yet the pro-i posed Patea Breakwater would be exposed: to a heavier sea than at New Plymouth,; and would require at least to be of equal'; strength. There is no doubt- that an outlay similar to ; that at Oamaru will ultimately be necessary, but if funds are not forthcoming at present, it is possible to execute the first five hundred feet with only, a> portion; pf; thei plant that'-will be requisite for the whole work. This is on account of the shallow water at even the last hundred feet. It was proposed to build ,a;portipn of the inner ‘einddu timber, but I think that it is absolutely necessary to have concrete-making machinery." ;It can he carried out almost as cheaply by building two concrete; walls and filling; between with rubble, stone. . I? could hot recommend any except work of a permanent charapteiy-as. it might be exposed to; tho sea for ycars before if was protected .by u continuation in concxete. . The proposed work would follow-the inner line of Sir-.'John Goode’s west pier, the only difference being that-the sharp bend;at4oo feet: from the cliff : would be rounded.off to suit a railway, curve. I do not ati present propose,-to build the outer, waif: of: the root and depot, but to place the concrete

mixers and sheds on the river Ibank inside: Ihe olifE ; because, as the work-may extend; over many years, it is safer to liavb tho plant.on the solid ground inaidesthan on the ; depot. The first! three hundred feet; of pier would, bo. built in situ as described above, with a layer of: concrete over the rubble. It would be of the.width shown on Sir John’s plans. The outer two; hundred would r bo solid concrete,,'-, the; lower » portion being -bagwork" 1 and the upper mass in situ. My estimates are as follows : ;; ■n ' / , ■/ - .

West Pier. Estimate for building; first 300 feet ; f Plant ... ... _ ... • £3OOO Buildings,&c.,and concrete pier.. 4 6844- • £BBI4 Soiling value of plant when finished ... i..A ! :2544 Cost of pier, exclusive of plant... 6300 Estimate,for building first 500 feet, Including that given above. . - . Plants ... . ... £3500. Buildings and concrete pier ... 13,209 £16,709 Selling value of plant ... ... 2709 Cost of pier, exclusive of plant... £14,000 Those estimates include,a fair amount fori risk and superintendence, and are not too high, considering the exposed Situation of the work. There is no special plant in the estimates, sueh as very large cranes or titans, but- everything is of such a nature as would find a read v sale in New Zealand. . Instead of building the outer 200 feet as described above, and, with the inferior plant, it would be much move advisable if the Board could raise £20,000 to buy the heavy plant necessary for the complete work at first, as the work/ on the whole could be more cheaply executed. For example there would be about one half the risk, and a large quantity of blocks would be made, which would contain much less cement than is necessary to put

in situ work, and, in bad weather, there would always bo work for the men, making blocks, which would enable a permanent body of men, trained to the work, to be kept on at from Is to Is Gd per day less wages. In this case the first 300 feet would be built as described before, but the remainder would be blocks resting on foundation bags where necessary, and levelled up with concrete in situ. Estimate for building the first 500 feet of West pier including all the heavy plant necessary for the completion of the whole work and including block, building, yards, and railway : Plant ... ... .. ... £7OOO Block yard and Railway ... 2000 Buildings and concrete pier ... 12,153 £21,153 Selling value of plant... ... £5,215 Do. do. of railway and moulds 753 Cost of pier exclusive of plant 15,100 In this case the Board would be in possession of all the requisite plant for continuing the work in future, and would h j :? able to utilize small sums such as two qjt three thousand pounds at a time, whilst they do not get the proper plant at first they will not be able to go beyond the first 500 feet till they are able to raise at least ten or fifteen thousand pounds again. I may point out also that I estimate the cost of the pier itself as £13,200 in the one case, and only £12,153 in the other so that there would be a saving of least £IOOO by getting the wholeplant. The last point to he considered 'is what tax would be necessary in order to carry out the work. This I will not enter on at any length, but may point out that if money can be got at G per cent, interest and one per cent, sinking fund, it would be only necessary to raise £1,400 a year to pay for £20,000. I have not tire proper data at hand, but believe a threepenny rate on the district would more than covrr it. If we consider that the value of land has risen fully, one third or 33 percent, since the s.s Patea began trading to the district, and that fully two-thirds of this increase is due to the superior facilities given to shipping compared, witli the time when everything had to come via Wanganui. I think-the country would be fully justified in going on with the work as a good paying investment. In conclusion, I would advise the Board to try and go on with the first three hundred feet, and before that is finished they will be in a better position to determine what course they will pursue in future. I have, &c., John Thomson, Marine Engineer. It was directed that the report should lie on the table for consideration of the new Board. s