CS16A - Concurrent Session 16A: Development of a Consistent Framework: Risk Prioritization for 36 Unsafe, High Hazard Dams in Massachusetts

Dam owners/regulators are responsible for addressing risks related to unsafe dams such as loss of life from predictable and unpredictable catastrophic events including dam failure. Aging infrastructure, limited resources, and increasing development along downstream reaches complicate this responsibility. Funding from the FEMA High Hazard Potential Dams (HHPD) Grant Program is helping owners/regulators address risks associated with dam safety issues.

The Massachusetts Department of Conservation & Recreation Office of Dam Safety (MA ODS) realized the importance of the FEMA HHPD program in addressing dam safety issues related to dams in Poor or Unsafe condition in Massachusetts. From a large portfolio of more than 315 high hazard dams, MA ODS identified 36 dams that would qualify for HHPD funding. With funding approved, MA ODS embarked on a portfolio screening level risk analysis for the 36 dams and to advance the MA dams risk program for future HHPD grant applications. The objective was to develop a risk prioritization matrix coupled with scope and costs to repair/remove dams that rank as the highest priorities.

Consistency and efficiency were predominant goals in developing the risk screening program for the 36 high hazard dams. The approach was especially challenging given the inconsistencies in previous studies. The client/consultant team collaborated on a scope of work that involved the following key tasks:

1. Evaluate the likelihood of failure for each dam under static, seismic, and hydrologic loading conditions.
2. Develop a dam break model for each dam using DSS-WISE and estimate consequences including population at risk (PAR), economic/environmental losses, and community impact.
3. Compile a risk-based prioritization matrix based upon likelihood and consequences of failure.
4. Rank the dams based upon level of risk to the public.
5. Develop scope and cost to repair or remove dams that rank as the highest priorities.

As the FEMA HHPD program is deployed across the U.S., risk screening projects similar to MA ODS’s can help guide future projects for the repair or removal of unsafe dams. MA ODS will use the findings of risk informed dam prioritization to apply for future HHPD grant funding to repair/remove the dams, starting with those that pose the greatest risk to the public.

This presentation will summarize the grant application process and provide a discussion of the combined quantitative and qualitative risk analysis framework developed to rank the 36 high hazard dams in the MA ODS portfolio based on likelihood of failure and consequences.