Analysis of PHMSA Spill Data for Pipeline Spill Risk Analysis

Analysis of the operating risk due to hazardous liquid pipeline spills is a challenging task. One reason for this is the fact that the spill probability and the magnitude of the release are both difficult to quantify for any particular pipeline. One source of comprehensive information regarding spills in the United States is the Department of Transportation (DOT) Pipeline and Hazardous Materials Safety Administration (PHMSA) hazardous incident database. This database is a mandatory compendium of spill incidents dating from 1968, and relies on self-reporting on the part of pipeline operators. We use this database to calculate historical average spill incident rates for various designated spill causes, and demonstrate a methodology using a tail risk analysis of the limited release orifice information supplied by the database to calculate a more complete aperture probability distribution for those causes. The incident rates developed by this analysis are then adapted to obtain more reliable incident rates for a particular pipeline by using the PHMSA results as a prior estimate and implementing a Bayesian posterior update based on historical sparse spill information for that system. We conclude by showing how the information obtained can be used in conjunction with pipeline hydraulic, leak detection performance, logistic response, and other models to perform a probabilistic cost-based risk analysis for the pipeline system.