Framework for Assessing Integrity of Natural Gas Distribution Pipes in Landslide Areas

ABSTRACT: A framework was developed to assess and manage the gas distribution system in areas impacted by slow moving landslides recognizing that ruptures or leaks in the system could pose significant damage to the public, properties, environment and reputation. This paper discusses the analytical approaches developed to assess the hazard (i.e., likelihood of failure) and the risk management approach implemented through monitoring and inspection programs. The analytical methods have been developed to correlate the measured ground displacement to pipe strain (or stress) by considering the pipe-soil interaction. Once the ground displacement is known, a screening-level analysis is performed to identify the pipe segments with high likelihood of failure. The threshold ground displacement levels corresponding to different hazard ratings have been developed using these analytical empirical fragility models for different pipe sizes by considering typical soil and burial conditions. Once identified, the higher risk areas are analyzed using site-specific conditions. Although limited in size, the existing leak database indicate this approach accurately identifies the critical pipe components and time when remediation measures are required. The paper discusses the implementation of this approach in three landslide areas in British Columbia.