Intuition & Logic was retained by Jefferson County, Missouri to evaluate the proposed realignment of Romaine Creek Road to determine if the proposed realignment would adversely impact the flood elevations or floodway of Sugar Creek and if so, what options were available to mitigate the impact.



The project study area begins at the Sugar Creek confluence with Saline Creek and extends upstream approximately 5,000 feet and includes modeling four bridge crossings. Intuition & Logic developed the model from LiDAR survey data supplemented with topographic survey of the channel thalweg and bridge openings.  The analysis also incorporated FEMA’s recently revised flood modeling data for Saline Creek.


Our analysis built on the FEMA tailwater conditions from Saline Creek and developed the floodway limits for the existing and proposed conditions.  Our analysis found that approximately 500 feet of the proposed roadway realignment would be located in the floodway.  Our analysis also found that the high bedload in Sugar Creek was causing flood capacity issues at the Romaine Creek Road Bridge. Our recommendations identified options for realignment of the roadway and modifications to the floodplain that would maintain the flow carrying capacity.  All the options identified would allow the County to pursue a No-Rise for the project.