Design and Installation of Distributed Fiber Optic Sensing Technology to Monitor HDPE Pipelines at an Earthquake Fault Crossing

The Summit Pressure Zone South Pipeline Replacement, Phase 1 project included approximately 5,000 linear feet (LF) of 24-in. steel pipeline in various streets in Berkeley, California, in addition to 700 LF of 36-in. high density polyethylene (HDPE) and 500 LF of 22-in. HDPE pipelines to cross the Hayward Fault in Claremont Avenue on the Oakland/Berkeley border. The transmission pipelines cross the Hayward Fault in an area which experiences significant ground movement resulting in several previous pipeline failures. East Bay Municipal Utility District (EBMUD) worked with researchers at University of California, Berkeley (UCB), to develop a system that would be able to monitor and measure pipeline strain in a robust, sensitive, distributed, and accurate way. The team explored various technologies and applications to determine which were most viable. The distributed fiber optic sensing (DFOS) system was selected as the most appropriate method to achieve the goals. Installation of the HDPE pipelines in this area was difficult due to field conditions, and installation of the fiber optic cables in the trench presented further challenges. A collaborative contractor and an adaptable team from EBMUD and UCB allowed the project to overcome these challenges and install a successful project. The system was brought online in summer 2022, and the team has already received some interesting data about the pipeline behavior at the Hayward Fault crossing.