A new $118 million tunnel between the city of Orakei and Hobson Bay in New Zealand will replace a 90-year-old sewer that crosses the bay. A 270-ton boring machine drills through rock on one end, and lines the tunnel segment with precast concrete on the other end. A small train system removes the debris. In addition to replacing the old sewer, the new pipeline will provide significant storage capacity for high-flow periods of rainfall, officials said.

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