澳大利亚悉尼的污水系统。
北方主要下水管从居nction of Newtown and Parramatta roads, just at the city boundary, and runs to the junction of College and Liverpool streets. From here it continues along Liverpool street for some distance, thence across Lacrozea Valley and on through the hill to Edgecliff road. After coming through this it crosses the low sandy area at the head of Rose bay, once more plunges into the hillside opposite and finally reaches the ocean, about half a mile north of Ben Buckler. The total length of the whole is five and one-half miles. The sewer is oviform throughout and of varying dimensions. At the upper end it is five feet by four feet and gradually increases in size as it progresses, tili it reaches the last mile, when it becomes eight feet six inches by seven feet six inches. The materials used in the work were the most carefully combined bluestone concrete for the invert, or lower part of the sewer, and brickwork of specially made bricks for the soffit. This brickwork is packed solid to the rock throughout the tunnels with sandstone concrete. The greater part of the tunneling was done in sandstone rock, but some tunnels had also to be driven through wet shale and water-charged sand. In addition, there were a couple of stretches of low-lying, sandy country to be passed over. Over these last the sewer was carried on massive concrete foundations, and, when completed, was covered by an embankment. In going through the wet rock all sorts of precautions were taken to keep the water away from the works in progress, subducts or underneath drains being the means most frequently employed. But it was the water-charged sand that gave the most trouble. It occurred on the last contract, that for the ninety chains nearest the outlet, and had to be got through partly by open cutting and partly by tunneling. Of the first the depth was never less than thirty feet, while all possible expedients had to be resorted to to keep the water down. Nine centrifugal pumps were constantly at work, pumping wells were sunk at various spots, and a subduct was laid all along the centre of the sewer trench. The most interesting feature of the whole northern outfall sewer is certainly the outlet, which is absolutely unique of its kind, it being the result of the observation combined with the engineering ingenuity and skill of the departmental engineers. The sewer discharges into the ocean through the cliffs, but it is not to be supposed that it simply runs straight to the face of the cliff and there abruptly ends. During southerly, southeasterly or easterly gales, the waves on the coast attain enormous proportions and strike the coastline and the cliffs with extraordinary force. No person who has not actually witnessed it can form an idea of the magnitude of the waves which roll on this coast, or of the overwhelming force with which they strike the cliffs in heavy storms. It was to be feared that if the outlet were fixed at so low a level as to be within reach of their full force, so large a body of water would be thrown into it during storms as to seriously interfere with the discharge of the sewer. The board therefore suggested the formation within the sewer at a convenient distance of an expanding basin, where the waves would be partly broken and dispersed.
下水道距离悬崖有200英尺，距离三十六英尺长，二十四英尺宽，二十一英尺高。在这个腔室的中间，建成了一个巨大的堰，凹入海面上，并具有突出的水泥来支撑它并面向流。在堰厅，从腔室从腔室延伸到腔室的两侧，在地板的水平下是两个四英尺的圆形开口。腔室以外的两个出口隧道（也是四英尺圆形）的末端，它们在不同方向上穿透到悬崖的面部，彼此相吻成三十一度的角度。该图示出了腔室的内部布置，通过轴12英尺和145英尺高的轴获得的进入。该轴的顶部受砖包保护，该砖层高出约56英尺高，在悬崖上形成相当的地标。因此，腔室的工作很快：污水进入三个半英尺的井子（或S形）落下，并且会议将水浸分成两条溪流，该流绕过其侧面，通过堰墙中的开口，然后通过隧道找到前往海的路。每当大海高，海浪冲动了这些隧道中的一个或另一个隧道，只需将它们的所有力量消耗在堰的凹部上，这会让它们再次匆匆回到污水流，因此它们根本不会中断。即使应该两个波浪冲击，一个通过每个出口的同时，没有伤害，随着水将仅被抛入腔室的内部，它会立即跳回。 Of course, it is necessary that this part of the work should be constructed as strongly as possible, seeing what it has to withstand, and great care has been taken that it should be. Bluestone masonry and bluestone concrete alone have been used for all within the chamber. The shaft, which merely leads to it. is lined with brick packed solid to the rock with concrete. Every possible contingency has aho been provided against. The highly improbable risk of the four-foot openings in the weir wall becoming choked with rubbish has even been guarded against by leaving ample space for the sewage to flow over the wall lcfore it could do any harm to the main sewer, while from an overhead platform within the chamber any obstruction can be removed by grappling. There are also grooves into which stop boards may be lowered at any time, and the flow of sewage shut off from any channel. This novel and interesting chamber, together with its accessories, has always worked splendidly and seems an unqualified success—as it ought to be.
