Risk-Based Earthen Dam Design and Mitigation Considering ALARP for All Potential Consequences

A risk-based design approach for earthen dams (existing or proposed, for water or waste) has been developed and illustrated by a simple example. It is comprised of (1) a well-established “tolerability limit” for safety risk (maximum allowable annual probability of exceeding any particular number of equivalent fatalities), which must be met regardless of other aspects of performance; and (2) “as low as reasonably practicable” (ALARP) for all stewardship (environmental, safety, and social) risks, which is of primary interest to public/regulators, as well as for business (local financial and global corporate) risks, which is also of interest to the dam owner/corporation. The assessment of risks associated with any particular dam system option and their subsequent evaluation with respect to these criteria, if appropriately done as discussed in this paper, will lead to defensibly acceptable and best appropriate dam design.