1. Erosion Screening Process (ESP) The Society of American Military Engineers (SAME) Sacramento Post – California Water Conference Richard Millet, PE, GE - URS Wilbur Huang, PE, CFM - URS Mike Inamine, PE - DWR Steve Mahnke, PE - DWR October 27 th , 2009
2. GER Technical Directive Analyses Process Overview Erosion assessments are one of seven geotechnical evaluations completed under the Urban Levee Evaluations (ULE) Program and one component of the resulting Geotechnical Engineering Report (GER)
7. Erosion Screening Process (ESP) The Erosion Screening Process makes a qualitative assessment of the potential for erosion failure of levees within the various task areas of the ULGEP Any Fail Erosion Screening Process (ESP) Spreadsheet Estimate Total Erosion/ Levee Width (TE/LW) Levee Prism Geometry Test Pass/Fail Wind Fetch Length Test Pass/Fail Historical Performance Test Pass/Fail Flow Velocity and Erosion Surface Adequacy Test Pass/Fail Wind Wave Shear and Erosion Surface Adequacy Test Pass/Fail Task Area Levee Any Fail Pass All 3 Analyses Pass All 3 Tests Evaluation Erosion Risk Category Low Risk Low Risk Tier - 1 Tier - 2 Tier - 3 Geomorphology Analysis 5%< TE/LW <25% TE/LW > 25% Moderate Risk High Risk TE/LW < 5% Low Risk Optional Field Confirmation Field Reconnaissance Or Field Evaluation Pass/Fail
8. Study Area Hydraulic Model Coverage URS Sacramento River Sacramento Bypass Yolo Bypass Sacramento Deepwater Ship Channel
14. Erosion Screening Process (ESP) Any Fail Erosion Screening Process (ESP) Spreadsheet Estimate Total Erosion/ Levee Width (TE/LW) Levee Prism Geometry Test Pass/Fail Wind Fetch Length Test Pass/Fail Historical Performance Test Pass/Fail Flow Velocity and Erosion Surface Adequacy Test Pass/Fail Wind Wave Shear and Erosion Surface Adequacy Test Pass/Fail Task Area Levee Any Fail Pass All 3 Analyses Pass All 3 Tests Evaluation Erosion Risk Category Low Risk Low Risk Tier - 1 Tier - 2 Tier - 3 Geomorphology Analysis 5% < TE/LW <25% TE/LW > 25% Moderate Risk High Risk TE/LW < 5% Low Risk Optional Field Confirmation Field Reconnaissance Or Field Evaluation Pass/Fail
15. Tier Two – Velocity/Surface Adequacy Test 15.0 Good Rock (Riprap, Uniform Revetment) 10.0 Poor Rock (Soft Sandstone, Non-uniform Revetment) 8.0 Vegetation-lined Earth 6.0 Coarse Sand, Fine Gravel, Clay 3.5 Silt Clay, Soft Shale 2.0 Fine Sand, Sandy Silt Depth-Averaged Velocity at Channel Bend Mean Channel Velocity at Straight Channel Maximum Design Velocity (feet per second) Levee Material
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17. Tier Two – Wind Wave Shear/ Surface Adequacy Test 4.869 Boulder and Cobbles 1.058 Gravel (GP-GW) 0.094 Clay (CL, CH, SC, GC) 0.014 Sand (SP, SM and mixtures) 0.003 Silt (ML) Critical Shear Stress (psf – pounds per square foot) Levee Material
