What are some limitations of an interim flood response plan? What can go wrong?
• Interim flood protection must be installed in a timely manner according to flood forecasts by the National Weather Service. This prediction window can be only a couple of hours in the case of an ice jam or up to two of three days for a major flood. Predictions can change rapidly, and in the case of 2008, may stop altogether. • Flood barriers installed by contractors provide roughly two to four feet of additional protection to an approximate 24-foot flood in some areas. With the flat topography of the City, a flood level greater than 24 feet will cause widespread flooding. • The plan does not prevent sewer back flows. Plugs and storm sewer wells have to withstand an additional two feet of pressure. If the river rises fast, plugs and wells have a greater probability of failure. • Heavy rainfall may flood behind the protection if pumps can’t keep up. • Groundwater may seep through sandy soil to the surface behind flood protection measures in place. This has been known to occur in areas
