High Hazard Dam Assessments

Background

The Iowa Department of Natural Resources (DNR) received funding through FEMA’s Rehabilitation of High Hazard Potential Dams Grant Program (HHPD) and was seeking to develop a prioritized plan to categorize their portfolio of high hazard dams using a risk-based assessment process adopted by FEMA. To accomplish this, the Iowa DNR chose Houston Engineering, Inc. (HEI) to begin preliminary/assessment needs of 27 dams (later expanded to 39 dams) located statewide. Drawing from HEI’s extensive history of dam projects and expertise, HEI helped the Iowa DNR document and develop an understanding of the high hazard dams’ current state of shortcomings and/or deficiencies.

The Project

Our project team began the process by performing screen level assessments and taking an inventory of resources in accordance with FEMA’s guidance. This way, FEMA can easily check for completeness and facilitate funding opportunities for these dams in the future.

Downstream impacts will also be assessed for each of the dams. HEI will utilize LiDAR and conduct an analysis of surrounding urban areas. These are of particular importance to include, as these areas usually have a greater population at risk (PAR). HEI plans to assess these PARs by using a variety of GIS-friendly tools and “ground truth” by structure counts and related assumptions. A scan of the entire breach inundation footprint, homes, infrastructures, and major pipeline facilities will also be completed.
Potential risk reduction recommendations will also take place, in addition to development of mitigation alternatives. HEI will develop a report for each dam that addresses the scope, complexity, and magnitude of costs for the mitigation alternatives proposed.

By following the assessment protocol outlined in FEMA’s Federal Guidelines for Dam Safety Risk Management, this effort hopes to open avenues for the Iowa DNR for potential funding through FEMA’s HHPD. This in turn will bring about cost sharing opportunities across the state.