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Mounds View Stormwater Pond Assessment <br />3 RESULTS <br />July 2023 <br />3 RESULTS <br />Data collected from the pond surveys, sedimentation analysis, and basin analysis are presented in this <br />section. <br />3.1 BASIN ANALYSIS <br />The analysis in this study focused on the wet sedimentation basins. The physical properties of the wet <br />sedimentation basins are summarized in Table 3.1, which incorporates updated geometries based on the <br />survey data collected. Basin bathymetry and sediment accumulation maps can be found in Appendix B. <br />The updated geometry informs the extent of sediment accumulation which was used to identify and <br />prioritize the management strategies. <br />Determining the original permanent pool volume of a basin can be challenging when accurate data on the <br />as -built condition of the basin is not readily available. The basin sediment accumulation volumes were <br />calculated using the measured sediment volumes (difference between depth to refusal and depth to <br />sediment) and either the permanent pool volume (volume below the water surface elevation) or the dead <br />storage volume (volume below the outlet), depending on the basin conditions. <br />The sediment accumulation percentage is the sediment accumulation volume reported as a percentage of <br />the permanent pool volume. This percentage is calculated to determine if dredging should be <br />recommended. It is highly recommended that sediment be removed once 50% of the permanent pool <br />volume is reached. (Minnesota Stormwater Manual, 2021) <br />14 <br />