Dig that Creek or Tunnel that Creek? Case Study of Crossing San Tomas Aquino Creek with an Inverted Sewer Siphon in Santa Clara, California

摘要

The Walsh Avenue Trunk Sewer project in Santa Clara, CA involved the construction of over 10,000 feet of 24 to 30-inch trunk sewer. The majority of the sewer was installed using traditional open cut construction methods. The trunk sewer crosses San Tomas Aquino Creek using an inverted siphon. The inverted siphon is a twin barrel siphon (15.2-inch each) with a 23.6-inch air jumper. The original design included open cut installation of the legs of the siphon with the creek being crossed using microtunneling. Two-thirds of the way through the design, the design was changed to open cutting the entire crossing. During construction, the Contractor requested to use auger boring to install the upstream and downstream legs of the siphon. Since one of the legs of the siphon is much steeper than typically constructed, this presented construction challenges which will be presented and discussed. The creek was crossed using open cut construction methods.