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West Side CSO:
00The West Side CSO Project encompasses near-surface pipelines, a deep tunnel, and a pump station that collects and transports CSOs from West Portland to the Columbia Boulevard Treatment Plant. The project includes the design and construction of 18,162 feet of 14 foot diameter tunnel and 10,600 feet of connecting pipeline. The tunnel is being constructed in a single pass through soft ground (sand and gravel) at a depth of 120 feet in the presence of a water head exceeding 100 feet. This construction uses what is believed to be the first use of shielded tunnel boring machines (TBMs) of the slurry type in the United States.
00Upon completion, the new Swan Island Pump Station (SIPS) will be a 220 million gallons per day combined sewage pumping facility. Excavation will create an opening 135 foot diameter and 160 feet deep; dimensions that make the undertaking one of the largest and deepest ever carried out in soft ground in the United States. The excavation is adjacent to the Willamette River, and the groundwater cutoff includes jet grouting to a depth of 320 feet. The connecting pipeline runs through microtunnels 72, 84, and 108 inches in diameter that are being constructed using a single machine with three different external sleeve sizes.
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