Harbor Improvement

Western Star, 22 December 1911, Page 2

Harbor Improvement

Following Is tha raport on the proposed Harbor improvement Mr F, iV. Marcnaut, M. inst, C.a. • The con-da.on 01 lue enwanco bar to Jacobs River is capable of easy i improvement, i our funds being very I limited i dismiss any proposal to construct any training or otln®r struct ural worss lor the object desired. Any suiictural wor.v to be at all elective would be- very expems.vc, quite bey ond the means available and unwarranted by the! small sea-oorne trade of the town, moreover, any such works, -e-cn if within tae bounds df possibility, are always doubtful m beneficial result as tins cxpeuieuoq of this and other countries abundant.y proves, unless such worvs arc com-

uined with dredging operations. Rrobings and soundings of the bar show mat it is composed exclusively of hard compacted sand having uepth of wafer over it of three lent siv inches at low water spring tid.s. There is also the same depth over a hard gravel shoal insnore oi the bar, uith an average tidal range of seven feet six inches there is thus a depth oi eleven Let) at high water. -Study of the coastal couhguration and me position and form oi the bar, itself, convinces me that it is a local and isolated deposit and is not! feu and added to by coastal sand drift from 'the direction of the prevailing wind us is generally thq case. quently the bar can be dealt wmv and improved by dredging. I advise that you should procure a steam self propelling hopper barge of eighty tons capacity having a dredging G grab crane mounted on it). The coat fl of sik-h a plant afloat at Riverton would be about LSOUU. An improvement to the foregoing would be a suction pump such as i added to me small Row (Plymouth dredge, inis combined with a power--lui pump forcing water through nozzles round the mouth of the suction pipe would a dd very much to the vame and elliciency of Ibis plant for the special purpose for which it is required, The extra coat of such an addition would be about one thousand pounds. Seeing that your funds are limited to a total expenditure of seven thousand pounds, your Council may decide to obtain the plant costing £5300 and expend thq balanpa ixl wording it. The working cost of this plant would bo about nine hundred pounds, a year, and 1 cst(imata that at a cost of fifteen hundred pounds the bar could bo dredged away to a width of channel of two hundred .and fifty feet having a low water depth of seven feet through the bar uiud gravel shoal inside. This gives fourteen feet six inches depth at high water allowing a vessel of the ‘Vllotoiti”- class of O no thousuad ton burden to work the port, on a loaded draft of eleven

lect, When dredging the channel it will be necessary to temporarily define it on opo side by numbered bars driven in at one hundred feet intervals the tops of them to extend say three feet jabdye high v/ateij. Unless) is done, work will be wasted in the process and some ground loft untouched. Without such guides reliable records cannot be kcplt ol the nuna ber of loads removed from each sec- A tion. The spoil from the excavated “ channel can be dumped close inshore to the seaward inside of rhe channel it will be driven ashore and no harm. I have worked the plants of iho chiu'octqr 1 recommend for thllsj pui> pose and they have given every satisfaction. After observation of the dredging work done in tine bar chan nel and round the wharf it will be matter for consideration whether iho plant should pe retained for malnten ance of depth in the channel and at the wharl or sold. This class pi plant is %pry readily salcauly at

any time if bo desired. ‘ Mr March ant, who, was present, in reply to questions eaad he could not recommend purchasing a-second-hand plant, Hiring a drudge was also unsaustactory. Ho had purchased a Pristman dredge some yours ago lor some lour thousand pounds, but since Unit time the Government had imposed a duty. Ho was going ironic, and if the Council wished it, ho could order a suitable dredge and sup ei vise the work. Ho did the total cost would , eX oeed his estimate. The dredge would come out in small parts, and- would then be put together.. The dredrre loaded would

draw about live foot and when empty three feet six inches. The material on tile bar had come down the river for centuries, and if once cleared out it .would probably remain clear f or some years. There werie no traces of sand dm it which was prevalent in other places. So far as the present wmirl is concerned, a good deal could be done at present if the steamer uere Led to the structure with h e r heart to sea and-the propeller kept revolving it would have the effect of clearing away the bank there. In speaking of -the dredge he thought it w 0 uld be better to work with the ebb tide. Probably when the bottom ua* loosened-the sand would be carnod away. When the dredge was laid { III! imn 4 .\ i ■

lup nine water c o uld be put in thn# boiler, and a coating could To on which would keep it from rusting, throe hands would be required to work the dredge. A contract would h 8 '-t for the dredge at Home, and it would probably take four months to complete. The parts would then 1)0 shipped, and the rivdttina done on arrival. The costl of rivetting f JfcS’is jtrra |ii» SPfcSW STt r onnalion on tho subject.