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 10,000feet of 24 to 30-inch trunk sewer. The majority of the sewer was installed using traditional open cut constructionmethods. The trunk sewer crosses San Tomas Aquino Creek using an inverted siphon. The inverted siphon is atwin barrel siphon (15.2-inch each) with a 23.6-inch air jumper. The original design included open cut installationof the legs of the siphon with the creek being crossed using microtunneling. Two-thirds of the way through thedesign, the design was changed to open cutting the entire crossing. During construction, the Contractor requested touse auger boring to install the upstream and downstream legs of the siphon. Since one of the legs of the siphon ismuch steeper than typically constructed, this presented construction challenges which will be presented anddiscussed. The creek was crossed using open cut construction methods.