DRAINAGE BOARD INSPECTION

Evening Star, Issue 15395, 20 January 1914, Page 8

DRAINAGE BOARD INSPECTION

THE OUTFALL SITE AND THE PUMPING STATION. The casual visitor to Lawyer Head would never dream that it was the outfall for the sewage of a large town like Dunedin. There is no visible sign of either engineering works or any discharge from them. But anyone who chanced to be in the vicinitv yesterday afternoon would have had his curiosity whetted by the sight of a score or so pair of gum Soots and half as many hurricane lamps collected at a spot where beach and headland meet. Presently - through the sandhills came a body of men, who by their dress were evidently not Drainage Board workmen. With very little loss of time the " nines,” ‘‘eights," and “'sevens” were drawn on to feet of as nearly corresponding size as might be, and one by one the heavilybooted party disappeared into a hole In the sand. It is here that the gravitation outfall connects with the tunnel, and it was down the manhole marking the spot that the party proceeded. At the foot of the vertical ladder they found themselves in a roomy tunnel, along which sewage about ankle-deep was steadily flowing. Pumping for the day, which in a spell of dry weather like the present, is not continuous. had ceased some four or live hours earlier, and the How in tho tunnel was the residue that had not yet emptied itself put of the length of rising main and gravitation outfall. Conditions were altogether favorable for a.visit of inspection, for not only was the sewage flow very light, but the tide was low and the wind off shore. This allowed the party to walk along the considerable length of main tunnel in comparative comfort, tho only care needed being to guard against slipping on the slimy, curved invert, and. walking in such very unaccustomed footgear, a few found the job a trifle awkward. The tide and wind conditions mentioned allowed the visitors to go some distance along the pair of smaller tunnels into which the main drive bifurcates. These are.short, of diameter small enough to enforce stooping, and are steeply graded. The sewage follows one or other of them according to wind .and tide. If the waves push it back in one, it finds exit all the more easily by means of the other. The visitors, who were very largely men accustomed enough to other branches of drainage and sewerage work, spontaneously, if unconsciously corroborated the opinion of the Sydney engineer, Mr Cardew, that this was indeed an ideal outfall—none better could be imagined. What particularly took their fancy was the tremendous size of the air vent "which pushes up through the headland from the point where the tunnel bifurcates. It is perhaps some 90ft to the surface, and the shaft has a diameter of some Bft at a guess. But it is ■ not extravagently Targe. When in a S.W. storm the waves are pounding in at the southern bifurcation the value of so free a vent for the air that would otherwise be imprisoned is at once admitted by* those who have been below in heavy weather. They say that it is a nervetrying experience for the new chum.

It was probably because the great bulk of the party were plumbers that they took such interest in this mammoth air vent. At present (the chairman of the Drainage Board being, in indiffeient health) Mr Douglas is carrying out the chairman's duties, and he invited his brother masterplumbers to see tliis fine bit of engineering work, and later to see tho excellent plant at the pumping station. Thither the paa'ty, which included also representatives of the building trade, both contractors and architects, foregathered on tho return from Lawyer Head. They saw the three-phase motor, which, working a few Hours daily, easily copes with normal flow, set goincp One of the two Diesel oil engines, which now are only called on when heavy rains multiply the flow, was also set going in such little time and with such a minimum of fuss as to prove the oil engines an ideal stand-by should the electric curier.t be cut off, or should a sudden thunderstorm flush tho sewers. Then flanked by tiers of cases of benzine for the engines, the company sat down to refreshment iu the spotlessly clear, e nd pleasantly airy station, Mr Douglas presided, and a short toast list was gone through. After “ The King/’ Mr Douglas proposed “Tho Visitors,” responded to by Mr T. Christie (for the master-plumbers), Mr Dempster (for the Builders’ Association), and Dir K. Walden- (for tho architects of Dunedin). They all praised what they had seen, and especially complimented IMr Slinger on his achievement at, tho outfall, not only as an engineering feat, but as a most economical piece of work, costing £5,C00 odd, as against some £37,000 estimated by his predecessor to cover the Bird Island outfall scheme, fortunately abandoned in early infancy. And they lauded the efficiency of the outfall, which has never defiled” the beach, and which costs practically nothingtor maintenance. Though it has been in use five and a-half yens its fall of 3ft to the mile keeps it self-cleansing, the slipperiness mentioned being from a film which has taken five and a-half years to collect, for the sewer has never been cleaned because it never needed cleaning. Another toast was that of “ Other Local Bodies," proposed felicitously by Mr Burnett, and replied to by Mr J. H. Walker (on behalf of the Hospital Board) and by Mr Moller on.behalf of the Harbor Board, m speeches to which reference is made elsewhere. Tho toast of the “ Drainage Board ” was proposed by Mr Alex. Burt, and replied to by members present, of whom Mr Small made the most notable speech. The toast of “ The Staff ” was received with extra cordiality, if that were possible. It was responded to by Mr A. Slinger, who stated that a great deal of the credit for overcoming serious Obstacles to Lawyer Head as the outfall site was due to Mr Small, to whom the ratepayers were much indebted for a great avoidanve of trouble and a very big saving in money. The toast of “The Press,” proposed by Mr P. Foot, the board’s acting secretary, brought a particularly pleasant function to a close.