1. Runoff Pond Design, Lutsen, MN By Mark Greve

2. Problem Poplar River increases in sediment load near Lutsen ski hills Structure needed to slow flow and settle sediment out Find a location for structure that does not interfere with ski runs

3. Computer Modeling Used LIDAR data in ArcGIS to determine watersheds, slopes, lengths, etc. Also mapped roads, culverts and other points of interest Flow paths, culverts and watershed boundaries field-validated

4. Computer Modeling (cont.) Water Erosion Prediction Project (WEPP) model used to create slope model Inputs: climate data (10 yr), slope, land cover and soil types Outputs: total runoff, sediment load by particle size and areas of erosion

5. Computer Modeling (cont.) WEPP outputs transferred to Excel Hydrograph created from flow-routing table

6. Pond Design Two-pond system connected by ditch Trapezoidal cross-sections, 2:1 ratio on sides Riser pipe in center as outlet Emergency spillway included

7. More Computer Modeling Used flow equations for both pipe flow and flow over a weir to determine daily discharge Determined dimensions of pipe and ponds Calculated sediment reduction

8. Questions?