THE DRAINAGE SCHEME.

New Zealand Times, Volume XXXII, Issue 4982, 12 March 1877, Page 3

THE DRAINAGE SCHEME.

TO THE EDITOR OF THE NEW ZEALAND TIMES. Sie,—Having read Mr, Climie’s report, I agree that there are many points to recommend it. However, I think that the tunnel and pumping arrangement might be reconsidered with advantage; and if the plan here suggested be studied put, a great saving in cost would result. I would run out a jetty, say in the vicinity of Brown’s wharf, where sufficient, deep water could be found, under which construct the outlet of the sewers, terminating with a forked mouth leading into and connecting with two air-tight iron punts or tanks, specially contrived as receivers of the sewage. They should have hopper bottoms ; the sides should be double ; the space between the inner and outer skin when filled with water would sink the tank a sufficient depth to meet the gradient of the sewer, and as the tank filled, the water could be let off or pumped out, and replaced by air to give the required floating power. Each of the punts should have sufficient capacity for all sewage that would flow into it for a given period, say two days, three days, or a week. The , jetty should be so contrived that the punts could be floated into position near about low water. When one tank is full a shut-off valve should be closed, and a similar valve in the other fork opened, thus throwing the discharge into the second punt. A steam tug could thentakethe first puntiu tow at early convenience, and when outside the Heads the flap of the hopper being opened would release the contents. The harbor tug would find this service a substantial addition to her ordinary earnings. Sewage as a manure has not been found profitable, and an excellent leader in your issue of the 6th inst. explained the reasons as ascertained by a commission in England. I fear Mr. Crawford would find this to be so, and then the deposit from neglect might create a nuisance. If the coat of the tunnel, the engines (for I think there must be two), and cost of working them, be set against the punts and their working, the balance I feel convinced will be largely in favor of the punts. I merely throw out this as a suggestion. Mr. Climie’s scheme would only require that the fall of his main sewer should be reversed and the pumping dispensed with. All details being a matter of design and calculation are not necessary iu a communication of this kind.—l am, &c., X.Y.Z.