Knights Landing Small Community Flood Risk Reduction Feasibility Study July 2019 This Page Intentionally Left Blank Table of Contents Table of Contents ............................................................................................................. i List of Appendices .......................................................................................................... vii Acronyms and Abbreviations ......................................................................................... viii Executive Summary ........................................................................................................ 1 1 Purpose and Scope .............................................................................................. 7 1.1 Background ........................................................................................... 7 1.2 Purpose and Scope .............................................................................. 8 1.3 Location and Project Study Area .......................................................... 8 1.4 Related Plans, Programs, Studies, and Projects ................................ 11 Central Valley Flood Protection Plan ........................................ 11 Sacramento River Basinwide Feasibility Study ........................ 11 Lower Sacramento/Delta North Regional Flood Management Plan .......................................................................................... 12 Knights Landing Levee System Emergency Operations Plan Basic Plan 2018 ....................................................................... 12 DWR Non-Urban Levee Elevation Geotechnical Assessment Report ...................................................................................... 13 USACE Yolo Bypass Reconnaissance Study, March 1992 ..... 13 Levee System Wide Improvement Framework, Knights Landing U2 – Yolo Bypass -Service Area 6 Levee System ................... 14 Colusa Trough Drainage Canal (USACE 1993) ....................... 15 Sacramento River Flood Control Project, Mid-Valley Area Phase III Levee Reconstruction Project (USACE/CVFPB) .................. 15 Wallace Weir Improvements .................................................... 16 Agricultural Floodplain Ordinance Task Force Technical Memorandum ........................................................................... 17 The Yolo County Habitat Conservation Plan ............................ 17 Yolo County and Knights Landing General Plans .................... 17 Knights Landing Revitalization Study ....................................... 18 1.5 Stakeholder Engagement ................................................................... 18 2 Problem Identification, Opportunities and Constraints ........................................ 21 2.1 Existing Conditions ............................................................................. 21 Hydrology and Hydraulics ........................................................ 21 Topography and Levees .......................................................... 22 Existing Infrastructure .............................................................. 24 Levee Operations and Maintenance and Local Governance for Knights Landing Basin ............................................................. 25 Knights Landing Small Community Flood Risk Reduction Feasibility Study i Flood History ............................................................................ 25 Biological Resources ................................................................ 26 Tribal Cultural Resources ......................................................... 29 Water Supply............................................................................ 29 Funding Sources ...................................................................... 30 2.2 Problems ............................................................................................. 31 Flood Risk ................................................................................ 31 FEMA ....................................................................................... 37 Agricultural Sustainability ......................................................... 40 Habitat/Ecosystem Restoration ................................................ 41 Recreation ................................................................................ 41 Operations and Maintenance and Local Governance .............. 41 Water Supply Reliability ........................................................... 41 Ability to Pay ............................................................................ 42 2.3 Opportunities ...................................................................................... 42 Agricultural Sustainability ......................................................... 42 Habitat/Ecosystem Restoration ................................................ 42 Recreation ................................................................................ 42 Operations and Maintenance and Local Governance .............. 43 Water Supply Reliability ........................................................... 43 3 Plan Formulation ................................................................................................ 45 3.1 Planning Goals and Objectives ........................................................... 45 Flood Risk Reduction ............................................................... 45 Sustaining Agriculture .............................................................. 45 Improving Riverine Habitat Viability .......................................... 46 3.2 Alternatives Development ................................................................... 46 Flood Risk Reduction Alternative Development Measures ...... 47 Evaluation Criteria and Metrics ................................................ 47 3.3 Constraints and Other Considerations ................................................ 49 4 Structural Alternatives ........................................................................................ 51 4.1 Alternatives Description ...................................................................... 51 No Action Alternative ................................................................ 51 Alternative 1 ............................................................................. 51 Alternative 2 ............................................................................. 52 Alternative 3 ............................................................................. 52 Alternative 4 ............................................................................. 53 Alternative 5 ............................................................................. 53 Alternative 6 ............................................................................. 54 Alternative 7 ............................................................................. 54 Alternative 8 ............................................................................. 54 Alternative 9 ............................................................................. 54 Alternative 10 ........................................................................... 54 Alternative 11 ........................................................................... 55 Alternative 12 ........................................................................... 55 Alternative 13 ........................................................................... 55 Knights Landing Small Community Flood Risk Reduction Feasibility Study ii 4.2 Preliminary Screening of Structural Alternatives ................................. 75 Flood Risk Reduction ............................................................... 75 Agricultural Sustainability ......................................................... 75 Capital Cost ............................................................................. 76 Preliminary Evaluation ............................................................. 76 4.3 Proposed Remediations ...................................................................... 77 Through Seepage Remediation ............................................... 77 Underseepage and Through Seepage Remediation ................ 78 Underseepage, Through Seepage, and Stability Remediation 79 Stability Remediation ............................................................... 80 New Cross levee ...................................................................... 80 4.4 Description of Final Array of Structural Alternatives ............................ 81 Alternative 1 ............................................................................. 81 Alternative 3 ............................................................................. 82 Alternative 6 ............................................................................. 82 Alternative 11 ........................................................................... 83 Alternative 12 ........................................................................... 84 Alternative 13 ........................................................................... 85 4.5 Capital Costs ...................................................................................... 93 Cross levee .............................................................................. 93 Fix-in-Place Levee Improvements ............................................ 95 4.6 Financial Feasibility ............................................................................ 97 4.7 Trade-off Analysis