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Gisborne Times, Volume XXII, Issue 1733, 26 April 1906, Page 4

neotod to the present boilors, or a gis p’OI duoing plant capablo of dovol p ng say 90 bhp. A. drodgo of loss power t'len thin W >uld bo practically uolras for the to-.,vy work which would bo ontaibd by any >! tbo works tkoroin A suotiou pipo would be Sited to tbo bow of tho dr dgo and raised aud loworod as required by tbo crano at present usod for the purposo of dredging. A portion of the hopper well would rrquiro to be decked and bridged to support the orgine and pmrp. Tho bull generally, with oomparasivcly alight st flauiDg, is qu : ts oipable of canyirg such plant. The first cost of a steam engine or gas producing plant is s'ightly in favor of tho former, but the cost of running is greatly in favor of a gas producing p’n-it. The maio diflioully in oonneotion with tbe pumping of the Bpoil BBhcro is tho absecoe of suitable areas for receiving it without rooour.-e to a long pipe lino for tbe diechaige, Tbe areas available, assuming tho works reoommended be constructed, are situated at tbe back of tbo proposed berthage, abreast of the present town wharf, wbioh together with tbe area behind the proposed wall below tbe cattle yard?, would hold some 55,000 oubio yards, the balance om'd be pumped behind tbe breakwater or into tho Wa'kicae lagoon beyond tbe limit of Ihe euggeated floating basin, The length of pipe iioe inquired would be some 1500 feo\ and an allowance bae been made in the estimetos for this length of disoharge pipe. Them should be no objection to reclaimmg part of the Waikanae Lagoon, indeed it would be a considerable benefit were tueh accomplished, and by tbo construction cf a culvert thero would be no d.fficulty in keeping the upper part of tbe lagoon oonstent'y full or allowing its waters to me and fall with the tides as at present. I judge, however, lhat it would bo preferablo to koep it full, allowing disohaiga by an oveiflow channel over that periionof tbe lagoon wbioh won'd be reclamed, It is somewhat difficult to estimate whet tbe o st would be per oubic yard for dredging the papa, but I judge that the silt or mud ehould bo readily removed for 6J per cubic yard, stiff clay for Is per cubic yard, and tbo dredgable portion of tbe papa for about Is 81 per oubio yaid. By ornstruoting a sluiciog basin, as already referred to, the depth at the birthages could be m detained by scour at 15 feit at L.W.S T., and the channel in the fairway, say, 150 feet wide at 12 feet LWS T. These depths would admit of vessels of 14ft draught negotiating tbe harbor during ordinary cond.tions of weather, and the amount of dredging rc« quired would be as before given, 205,000 cubic yards,'of wbioh 110,000 cubic yards would probably be papa. Without recourse to a sluicing ba;in the ultimate depths which could be maintained by scour would to about 12 feet L.W.S T., and with this depth at the beitbages and 10 feet at L.W.S.T. in the fairway, tbe quantity of dredging would amount to 140.000 eubio yards, of which approximately 85,000 eubio yards would be mud and o’ay, aud 55,000 eubio yards papa. The limiting draught of vessels navigating tbo port at H.W.S.T. would be, say, 12 feet, or of tbe Moura class, whose loaded draught is lift 4£io. As this vessel is approximately 300 ft in length, and tbe width between tbe proposed berthages is 250 ft, she could net turn except at tbo swiqging basin indicated upon tho plan. Since my last visit tbe western wall has been extended a distanco of some 500 ft, until it now overlaps the breakwater by about 50ft, and, as was anticipated in my report cf January, 1904, a heavy sea rip prevails in tbe fairway during rough weather. To remedy this, it has, I understand, been suggested to construot dolphins or pile clusters in advance of tbe breakwater for the purpose of breaking the run of tbe seas, but I would advise that Ibis can bo much mere economically and satisfactorily effected by lowering tbe height of the wall to, say, three-quarter tide level for a distance of 350 ft from its terminus, and I would strongly urge this course in preference to tbe suggested dolphins, I would also advise (bat the papa ledge at

the vieduot should not be out away towards its seaward extremity, as it might be found advantageous to construct a couple of low groynes at this point to trap the sea rip whioh is deflected from tbe groyne to the breakwater tile of tie harbor.

I estimate the different portions of the work outlined abovo as follows : Equipping present dredge with a ]2’n centrifugal pump with cutting machinery on auction pipe, driven by 100 I.H.P. steam engine ... £1,750 Or. by a 90 B.H.P. gas engine supplied by gas producer plant £2,200 1500 ft 12in steel dieobargo piping, 400 ft floating with flexible joints £1,200 Tidal sluicing gates at junction of Taruheru and Waimala rivers £6,800 1100 ft wharf, Kaiii side ... ... £6,600 Or if retaining wall only ... £1.500 Retaining wall below present m.B.Z wharf to slip .: £BOO Dredging— Dredging to give 15ft at berthages and 12ft et L.W ST. throughout fairway £16,000 Dredging to give 12ft at berthages and 10ft at L.W.S.T. throughout fairway £9,100

No look for the passage of lighters to the Tarn! era has been 'n-luded in the sluice gat: s, as I understand it is only on ocoaiione lhat lighters navigate this reach, and et euoh periods the gates could be kept open. The cost of adding a lock suitable for lighters and small craft would amount to about £2OOO.

Properly designed sluice gates would not interfere with tbe free river disoharge during floods any more than the piers of the present bridge, wbioh may in part require protecting against scour, should the sluioe gates be constructed. Cors’deriDg tho state of tbo harbor, as shewn upon older plane, with its condition 10-day, it is pleasant to note that very considerable improvements have been m ide.