INVENTORY OF HISTORIC FAILURES

摘要

1. The primary failure modes associated with identified failures and near misses are: 1.1 Slope stability- caused by overly steep slopes, seepage, or erosion from overtopping or heavy rainfall 1.2 Pipe penetrations - caused by collapse of pipe, failure of plug, or failure of valve or stop-logs 1.3 Seepage - often caused by perched phreatic surface in ash 1.4 Piping - caused by seepage leading to internal erosion or piping along pipe penetrations 1.5 Overtopping - caused by breach of internal divider dike, heavy rainfall, mis-operation of pumping equipment, breach in pipe, or failure of valve or stop-logs 2. Operational problems often lead to one of the above failure modes 3. Knowledge used to develop PMFA guidance document for performing potential failure modes analysis of CCR impoundments.