The USACE Dam Safety Program is critical to ensuring the integrity and viability of dams so that they do not present unacceptable risks to the public, property, and the environment. Due to challenges posed by the COVID-19 pandemic, the Wilmington District applied a creative and innovative approach to the Periodic Inspection and Periodic Assessment (PIPA) for the Island Creek Dam. This approach will serve as a foundation for future collaboration with the USACE Enterprise and has provided some unexpected successes in delivery.
Island Creek Dam, located on the Roanoke River, is one of nine dams managed by the Dam Safety Program in the Wilmington District. This year, we scheduled a “hybrid” (virtual and traditional) inspection for the 5/10-year cycle at Island Creek Dam. We assembled a team consisting of engineers and geologists from the District office in Wilmington, and engineers, rangers, and mechanics from the project offices at John H. Kerr Dam, as well as 2 individuals assigned by the Risk Management Center to facilitate the subsequent Periodic Assessment (PA).
In order to increase distancing measures and reduce the risk of COVID exposure, some team members participated in the inspection virtually via email, phone, and video. Those attending in person observed distancing from others and used masks when distancing was not possible. The use of hand sanitizer was encouraged, due to the absence of running water at the project.
The inspection is a Periodic Inspection (PI) which occurs every five years and takes a detailed look at all aspects of the project affecting the safety of the dam. Between these five-year inspections, annual and frequent informal inspections are carried out by Engineering and Operations staff. Following the inspection, a Periodic Assessment was conducted by teammates virtually. This activity took several days to complete, in which participants viewed multiple web-meetings at the same time in order to display and see all the information that traditionally would have been plastered over conference room walls on large flipchart paper. Periodic Assessments are a routine type of risk assessment performed by the Corps and are scheduled every ten years to assess if any risks have changed since the previous assessment.
During this assessment, a process called a Potential Failure Mode Analysis is followed that considers all the various ways the dam could possibly fail. The team then looks at the likelihood of each failure mode occurring and what consequences could transpire. The result is an overall assessment of risk of the project, documented as a recommended Dam Safety Action Classification (DSAC), which prioritizes the urgency of reducing risk at that project versus other projects within the Corps’ inventory of dams. Risk reduction can include things like physical repairs or modifications to the dam. These repairs and modifications are performed to decrease the likelihood of dam failure. To lower consequences, there are behind the scenes procedures could be put in action, such as increased risk communication with those anticipated to be affected.
Based on previous risk assessments, Island Creek Dam is currently a DSAC 3 (Moderate Urgency), but the 2020 Periodic Assessment team is presently drafting a report that will recommend a less urgent DSAC. The addition of a filtered seepage berm at the dam was completed in 2019 and has significantly lowered the likelihood of failure for multiple failure modes, resulting in the recommendation of a less urgent DSAC. The report will go through a thorough review process before being presented to the USACE Dam Senior Oversight Group for concurrence and Headquarters approval prior to a DSAC officially being changed.