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13 Monitoring Visual surveillance and instrumentation monitoring are used in conjunction with each other to identify warning signs that might indicate the onset of a developing failure or incident. When used appropriately they can be very effective at identifying issues in sufficient time for successful intervention and mitigation. However, lack of knowledge, complacency, or overconfidence by inspectors and personnel evaluating monitoring data can lead to warning signs being missed or misunderstood. It is also a common human factor to normalize deviations observed in the physical condition of the structure over time. A crack in a spillway slab that has always been there can be viewed as “normal.” In this case more frequent or even more detailed inspections will not identify the crack as a potential issue because it has been labeled as a “normal deviance.” In addition, more frequent physical inspections are not always sufficient to identify risks and manage safety, and instead more comprehensive inspections and reviews are required when warranted by risks. The more substantial reviews that occur at a lesser frequency, such as five-year reviews versus annual inspections, often focus on changes based on observations from inspection, surveillance, monitoring, and operations during the prior five-year interval. Instead, these should be periodically supplemented by comprehensive review on the long term performance, including verifying design assumptions and comparing the original design and construction with current best practices. More comprehensive reviews should not only evaluate the physical condition of the dam, but also review the design, construction, operation, and history of past performance of each feature. Each comprehensive review should be conducted with a fresh set of eyes. Access constraints often prevent regular inspection of certain components such as steep slopes of spillways, embankments, and concrete dams; conduits; towers; etc. Although the advent of drones, ROV and other remote-access camera inspection has lessened this concern, there is still cost and effort involved in conducting these inspections, and technical expertise required to understand the observations. As with all other phases of the dam’s life cycle, technical understanding plays a big role in an effective surveillance and monitoring program. The dam safety surveillance and monitoring program needs to be developed, executed and reviewed by someone who understands and can recognize the relevance of warning signs. A well-informed plan should be developed based on an understanding of how the various components of a dam might fail and what surface expressions may correlate to a developing problem. This is often accomplished in the form of a Potential Failure Mode Analysis (PFMA) which identifies credible PFMs for the various features and the potential warning signs that may be detected in a monitoring program. Traditionally, PFMAs have focused only on breach-type failures resulting in catastrophic release of the reservoir. However, dam safety incidents that don’t progress to failure may still result in significant consequences (economic, social, environmental, etc.), particularly for the owner. The PFMs identified during the PFMA process can be utilized as a road map of what to look for during regular and comprehensive reviews. In addition, PFMAs can be a valuable tool in the owner’s overall risk management process. Maintenance Aging infrastructure requires periodic maintenance and repairs to continue to perform as designed. It is important to identify maintenance items in a timely fashion and even more important to make sure the repair doesn’t cause additional harm. There have been cases were repairs have actually masked the underlying issue, which makes it difficult for future  Budget constraints  Complacency and overconfidence  Insufficient technical understanding of owners and inspectors to recognize warning signs  Normalization of deviance  Access limitations  Lack of comprehensive reviews HUMAN FACTORS IN MONITORING