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Maine: Pro-Active Measures Identify At-Risk Culverts

Over the years in supporting presidential declarations, the Federal Emergency Management Agency has reimbursed millions of dollars for countless numbers of culvert repairs and road washouts to states, counties, and local communities. Culvert failures and subsequent road washouts have not only been expensive, but have led to serious business interruptions, as well as major inconveniences to residents. In many cases, the culverts were replaced with a larger culvert or hydraulic structure to mitigate future damage. In Maine, the Silver Jackets team is working with the Maine Interagency Stream Connectivity Working Group to assist with an analysis that will provide communities with information needed to identify public works structures that will be threatened in extreme weather events. By increasing public awareness at the local level and encouraging preemptive mitigation efforts, this project will reduce flood risk caused by undersized structures.

The Maine pilot project was completed in August 2012.  The project supported an ongoing multi-agency program to complete a hydraulic failure analysis for more than 600 road crossing structures.  The State’s Hazard Mitigation Plan states that “the greatest amount of damage from flooding events occurs to the roadway system, both state and municipal roads, bridges, culverts and ditches”; replacing priority undersized culverts before floods occur avoids significant impacts.  

The $40k pilot study investment leveraged $80.8k from Maine agencies and the U.S. Fish and Wildlife Service.  The hydraulic analysis identifies the expected capacity of each structure for various extreme weather events, providing 21 communities with the information required to prioritize culvert and bridge replacements.  Assuming that providing for increased hydraulic capacity doubles culvert installation costs and that approximately 10% of the culverts are high-risk and warrant enlarging, the project investment can be roughly estimated to mitigate approximately $700,000 of replacement value plus the extensive costs associated with reconstructing roads damaged from the effects of stream crossing failures.  

At a recent meeting, community officials were eager to obtain and make use of the data.  The data will also be integrated into the Federal Emergency Management Agency’s non-regulatory RiskMAP product as “other points of mitigation interest.”