Ivor-Smith DJNadagiri SPettersson CBRoy G2010-02-152010-02-151989http://hdl.handle.net/1969.3/23301229-247The Coastal Water Authority's 2,740mm/2,590mm pipeline, known as the Northwest Lateral Project, will transport raw water from an existing pipeline over 14.3 km to the City of Houston's East Water Purification Plant. The new pipeline crosses under Houston Ship Channel and Greens Bayou in tunnels at approximately 30.5m and 25.9m depths, which present unique experiences in tunneling under open bodies of water in the Gulf Coast's soft ground conditions. An earth pressure balance TBM is being used for the deep tunnel sections where the ground demonstrates high overload factors and variable conditions ranging from clays to silty sands. This paper discusses the design approach for the tunnels and shafts, ground conditions, constructability, and selection of the primary lining systemTunneling MachinesTunnels and Tunneling -- ConstructionWaterWater Supply Tunnels--Houston,TexasCONF