Harbor Improvements at Shortland.

Thames Star, Volume XIV, Issue 4654, 4 December 1883, Page 2

Harbor Improvements at Shortland.

The following is the' Harbormaster's report, chiefly bearing on the above subject, which was laid before the Board at their meeting this afternoon:— To the Chairman and Members of the Thames Harbor Board.—G-entlemen, —l beg to famish you with a plan of proposed sheet piling of Shortland channel. You will see from the plan the direction the various channels take, numbered 1 to 5. The old channel on plan is the one in which it is proposed to concentrate all the water which finds its way out of the various outlets shown. The new channel has several advantages over the old. It has a more natural course, and the bottom is not so hard as that in the old channel, which is chiefly shingle ; that in the new being composed of a crust of stiffish mud and pipis, with about six inches of light sand on top, and under the crust soft mud. About the vicinity of No. 5 channel the water is very shoal, and the channel is inclined to split, and as it approaches the bend lower down, at B on plan, the water deepens considerably, but the pipi banks shown split the channel there, though leaving plenty of room. I am of opinion that if sheet piling was carried down as far as the points shown on plan, the first fresh would considesably deepen the part shown beyond, though there is the possibility of it breaking out anywhere about the intervening space, if it does not cut the ground away as supposed. But I em strongly of opinion that a good scour will be effected on account of the fall in the ground, between the bottom of the channel abreast of the lighthouse and tide guage placed upon the lower pipi bank. The foot of the tide guage is just awash at dead low water, and on the incoming tide, when the water reaches the base of the lighthouse, there is 4ft. 7inche3 of water, showing on the guage. The base of the lighthouse is 13 inches higher than the bottom in the centre of the channel abreast of the lighthouse, thus showing a fall of 3ft. 6in. in the ground between the two points named, in a distance of about 40' chains, consequently there should be a good scour. Looking down stream from Shortland wharf the freshes have shown a tendency to encroach on the side at point II on plan, and a wing as marked should stop such encroachments, and strike the water into the natural course. The ground is pegged out as shown on plan, end I consider the length shown, vis., about 2800 ft., to be necessary to effect a good scour, and concentrate all the water as proposed. Your Committee recommend ti tree wattling for the bulk of the work ; I cannot agree with their recommendation, for various reasons: Wattling presents too rough a surface, and is liable (as proved by the groins now in existence) to catch and retain any moving substance; and, also, that wattling cannot be got lower down than the ground line, and it is necessary that whatever is done should be driven considerably below the surface, as with a smooth surface, such as sheet

piling, there is every probability of the ground being cut* away considerably in j the immediate vicinity, as proved by Shortland Wharf, where there is npw comparatively deep water* The proposed new channel will require snagging. I went over the ground again yesterday, and should judge that a very moderate sum would clear out all roots, snags, and obstructions, as at present seen, and I do not think there is much buried timber, as I tried the ground frequently with a boring rod. The' channel will require about four beacons ; they should be screw piles, so that they could be shifted if required at any future time. At the bottom of the plan is a section of proposed style of sheet-pilinec; viz., a 3 feet wall above surface, with 6ffc driven into the ground, and a pile at every 20ft, at the back for strengthening. Such a wall will present a smooth surface, with no projections where anything, can stick, consequently everything musjtgo with the trend of the wall. Specificatibns can be pre Dared at any time, after approval of plans. Work at the Goods Wharf has been confined to keeping the plankiug in repair and carrying on the silt-works wall. Capt. Farquhar has complained lately of a lumpleft when dredj-ing operations ceased, at the end berth at the wharf. I have inspected the place, and find that threequarters of the steamers length lies in the hole cut by the dredge ; the other portion lies on the hard lump left. A vessel lying in such a position with a heavy cargo in would be liable to strain, and I should rocommend that a contract be let for taking out about 20ft. in length and 16ft. in breadth about 3ft: deep. It could, be done with shovels and wheeled under the wharf. The stuff'is prefcty hard and'stiff, there would be very little chance of it shifting from there. .

The remainder of the report deals with the filling in of a portion of Goods Wharf for which tenders have been called; and states that the new portion of Shortland Wharf will be finished by the end of the year.