HARBOR WORKS.

Taranaki Daily News, 16 April 1921, Page 5

HARBOR WORKS.

TEST OF PARITUTU. SUITABILITY OF STONE BOARD’S MONTHLY MEETING. The New Plymouth Harbor Board met yesterday. Present: Messrs New. ton King (chairman), C. E. Bellringer, C. 11. Burgess, E Maxwell) J. McClugguge, J. 8. Connett, D. J. Hughes, and C. A. Wilkinson. ENGINEER’S REPORT. The engineer (Mr. G. W. Baxter Lowson) reported:—The past month has been very quiet, the only event of any interest being the test blast at Paritutu. This blast was fired on April 8 with good results, the charge consisting of 96 cases of Monobel and two of gelignite, a total of 2 1-5 tons. The Henderson tunnel was driven about another 10 feet to a depth of 38 feet and two side chambers (13ft x 10ft respectively) were driven to form a T at the head. Approximately 30,000 tons of stone came away. During the month, rough weather interfered with out dredging operations and tiie running of the Thomas King, and in conjunction with the Easter holidays, lessened considerably the output from both these sources. It is very evident that the board must agree to some definite working plan when they augment their present working force, the present system of concentration upon one job only—and that a break* water—affording no means of diverting labor and material to useful works where heavy seas interfere with the regular jobs on hand. The patent slip at Wellington is not yet available for the Paritutu, and her hopper doors are now leaking so badly that they will not retain sand dredgings, and may have to be repaired before the vessel leaves for Wellington. The dredge was engaged practically all the month on new ground, only, 1200 tons i being maintenance dredging. Most of 1 the spoil wa* dumped on the seaward aide of the breakwater extension. The month’s output shows 3250 tons from the third outer basin cut, 1850 tons from the inside cut, 800 tons from the third fairway cut, and 400 tons from alongside the inside eastern berth. General maintenance has been attended to during the month. HARBORMASTER’S REPORT. The report of the harbormaster (Captain W. Waller) stated that for the four-weekly period ending on April f 21 vessels had entered the port, the aggregate tonnage being 24,397 tons. Tilt imports amounted to 10,127 tons, anc the exports were 3740 tons, the granatotal being ’3,867 tons, There were (3511 tons of Government coal landed EXTENSION OF BREAKWATER The engineer’s report contained the following reference to the extension of the breakwater: The Thomas King dumped 2760 tons of stone on the breakwater extensions during the month, sonic of this stone being taken from off the spit formed inside the breakwater end. Three hundred and ninety-six tons of heavy stone were placed on the apron of the- present breakwater. It is interesting to note that this protective apron has absorbed practically all the large stone* from the quarries since the works recommenced, and although this work is evidently looked upon as maintenance, it really should be charged to the initial cost of the breakwater construction, as in my opinion it will require constant attention until it reaches a batter down below low water probably as flex as 1 in 5, and consequently cannot be considered as completed until then. Keeping this in mind, and taking into consideration the present day cost of cement and labor, the board will have some idea of the cost of extending the breakwater in concrete and protecting it with a suitable apron. Consequently I feel justified in advising the construction of the extension in rubble, with a light concrete cap and grouting, but if the work is carried out in this manner, the board must be prepared for probably serious mishaps to the work whilst in progress and until- the seaward apron reaches its natural slope. Personally. I believe we can regulate the work so that no very serious damage will occur, but not being able to avail ourselves of the trestle-work commonly used in such cases, there is a certain risk attached to the undertalcing, and I feel bound to warn the board of this beforehand. As regards the stone for the extension, I recommend that it come from Paritutu. The test blast disclosed the fact that suitable stone is to be obtained here in large quantities; 80 per cent of the stftne brought down is suitable for harbor works, fully 46 per cent of this being 2A tons hi weight and over. Despite the fact that suitable stone is also to be found at Moturoa—and it might be advisable for the board to contradict any rumors to the contrary—it would seem to be a wise policy to reserve it for the Meturoa wall, which in itself may absorb most of the large stone to be found in the island. INCREASED COST. In reply to questions, Mr. Lowson said the present breakwater cost £56- per lineal foot, but the same kind of construction to-day would inyolve. an expenditure of £l2O per foot. Cement would cost about three times as much and labor roughly about double, as compared with the original construction. In view of this he proposed to overcome the difficulty bv an extension in rubble with only a light concrete cap aiul grouting. This could be done for £ov per foot. Answering the chairman, Mr Lowson said the probable mishaps, which he mentioned, might arise through storms or heavy weather damaging the works while in progress. He did not think there was any great danger, however. He ' said he proposed to carry on the work by nutting the atone out by crane from the end of the breakwater, and by end-tip and side-tip trucks. The engineer is to submit a detailea report on his proposal, to the next meeting of tha board. In reply to members of the board, Mr. Ijowson said the quality of the stone in Paritutu was quite satisfactory. There was no sign that the quality and size of the stone would deteriorate when operations took the quarry further into the rock Experience in the bottom tunnel was that the further they progressed the harder was tly> core. A similar experience had beeu met with at the Moturoa quarry. _■