The Upper Northwest Interceptor 1&2 Tunnel (UNWI 1&2) is currently under construction by Sacramento Regional County Sanitation District (SRCSD). This 144-inch inside diameter wastewater tunnel is being constructed in soft ground below the groundwater table using an earth pressure balance tunneling machine. The tunnel is supported with precast concrete segments lined with PVC. This is the first use of precast PVC lined concrete segments to construct a sewer tunnel in the United States. In the past, large diameter sewer tunnels have typically been constructed using pipe jacking, a two pass system, or by adding a liner after construction. Using PVC lined concrete segments to construct sewer runnels offers the industry an alternative approach.
展开▼
