Lower Northwest Interceptor's Sacramento River Crossings Near Completion Two tunnels are required to cross the Sacramento River in California. The two tunnels are part of a massive 59.5 km sewer project named the Lower Northwest Interceptor. The interceptor, divided into nine, more manageable projects, runs through the city of Sacramento's Natomas area, through West Sacramento and down rural Yolo County before connecting to the treatment plant in Elk Grove (see alignment map). The whole pipeline will have 26 tunnels, including the two crossings under the Sacramento River. There also will be a tunnel under the Deep Water Channel in West Sacramento. Others will snake under creeks and streets, including Watt Avenue, and a school yard. The 600 m-long north Sacramento River crossing is located east of the I-80 Interstate Bridge, connecting Yolo County to Sacramento County near the Freeport Bridge. The 631 m-long south Sacramento River crossing is north of Sacramento's Freeport Bridge, connecting Natomas to West Sacramento. The Sacramento River tunnels are 4.27 m in diameter.The client is the Sacramento Regional County Sanitation District. The engineering company is Hatch Mott MacDonald. The contractor is Affholder, who drove the tunnels by a pair of Lovat EPB TBMs. Computerized measurements were used to drive the TBMs and align the 22.9 cm-thick concrete segments that form the tunnels. Visit www.lovat.com, www.insituform.com and www.hatchmott.comThe construction of bulkheads in the tunnel for installation of the low density cellular concrete that will fill the annular space in the tunnel was completed at the south Sacramento River crossing as of 21st January, 2006. Two 1.7 m-diameter pipes will be installed in the south tunnel. The contractor continued installation of invert screed rail and started placement of invert concrete at the northern Sacramento River crossing as of 21st January, 2006. They continued to demobilize the Lovat EPB TBM, remove utilities and clean the tunnel as of 7th January, 2006. The gaps will be packed with additional concrete. Once built, the north tunnel also will be fitted with sewer pipes and then filled in.Work is expected to continue through the summer of 2006. By the end of 2006, the USD22 million South Sacramento crossing project will provide sewer service for 200,000 residents in the growing northern Sacramento County area and West Sacramento. The Lower Northwest Interceptor is expected to serve approximately 200,000 households and carry peak wet weather flows of up to 757,082,400 litres a day. The final cost of USD592 million includes design, land acquisition, construction and staff costs. Click us/87. Read more in E-News Weekly 39/2005 & 27/2005. Visit www.srcsd.com and www.lowernorthwest.com 06/06.