CONSTRUCTION OF THE UNWI 12 TUNNEL-SACRAMENTO, CALIFORNIA

摘要

The Upper Northwest Interceptor (UNWI) project constructed for the Sacramento Regional County Sanitation District (SRCSD) is comprised of approximately 30.5 km (18.9 mi) of sewer conveyance pipeline ranging from 0.6 m (24 in) to 3.6 m (144 in) in diameter. UNWI Sections 1&2 make up the longest and largest diameter pipelines in the system. The project consists of approximately 5.8 km (19,240 ft) of 3.6 m (144 in) inside diameter pipeline constructed using Earth Pressure Balance tunneling methodology. A unique tunnel lining, comprised of six-piece precast concrete segments, integrally lined with Ameron T-Lock PVC lining was used. Along with the tunnel, the project also included the construction of 23 access manholes, three lateral connections and two large shafts for transition structures connecting to previously completed sections of the UNWI system. Surface construction was limited to a challenging five month period each year due to numerous environmental factors. This paper will describe the work performed during the tunneling, liner welding and transition structure construction works.