Barr assisted the Ramsey-Washington Metro Watershed District with reducing flood risk in the Snail Lake and Grass Lake areas. We evaluated ways to lower flood levels in the area’s water bodies, reduce the risk of flooding to habitable structures, and lessen the impacts to surrounding properties. Specifically, we studied possible changes to overflow and outlet elevations of water bodies in the system, pipe changes to modify discharge rates and volumes, and the possibility of lowering the existing 15-inch reinforced-concrete pipe under Highway 694.
To evaluate the risks involved in undertaking the recommended actions, Barr surveyed low points of concern not covered by recent previous surveys. We used monitoring data that the district had collected for the area and expanded an existing XP-SWMM model. In addition, the Metropolitan Council’s groundwater flow model of the Twin Cities was employed to create a more localized, detailed version for use in evaluating options.
The outcomes of this study are updated flood levels of Snail and Grass lakes for potential management and regulatory use by the district and the implementation of flood management features that optimize flood storage while protecting habitable structures. In addition, modeling results were shared regularly with the district’s member cities to help them in their own flood-management and communication efforts in the area.