DRAFT Draft Conceptual Design Report Bolinas Lagoon North End Restoration Project Marin County Parks and Open Space District August 2017 DRAFT Draft Conceptual Design Report DRAFT Marin County Parks and Open Space District Prepared for: Marin County Parks and Open Space District 3501 Civic Center Drive Suite 260 San Rafael, CA 94903 Prepared by: AECOM 300 Lakeside Drive Suite #400 Oakland, CA, 94612 aecom.com Prepared in association with: Carmen Ecological Consulting, Watershed Sciences, Peter Baye Ecological Consulting Prepared for: Marin County Parks and Open Space District AECOM ǀ Carmen Ecological, Watershed Sciences, and Peter Baye Consulting Draft Conceptual Design Report DRAFT Marin County Parks and Open Space District Table of Contents Executive Summary ................................................................................................................................................. ES-1 PART I – PROJECT OVERVIEW ................................................................................................................................... 3 1. Introduction ......................................................................................................................................................... 3 1.1 Project Location ....................................................................................................................................... 4 1.2 Purpose and Need ................................................................................................................................... 4 1.3 Project History ......................................................................................................................................... 7 1.4 Report Components ................................................................................................................................ 8 1.5 Stakeholder Input .................................................................................................................................... 8 2. Goals and Objectives ......................................................................................................................................... 9 3. Existing Conditions ........................................................................................................................................... 10 3.1 Hydrology .............................................................................................................................................. 12 3.1.1 Creeks and Freshwater ......................................................................................................................... 12 3.1.2 Tidal and Brackish Water ....................................................................................................................... 13 3.2 Geology and Tectonic Activity ................................................................................................................ 13 3.2.1 Geotechnical Borings ............................................................................................................................ 14 3.3 Habitats and Wildlife .............................................................................................................................. 16 3.4 Cultural Resources ................................................................................................................................ 16 3.5 Climate Change and Sea Level Rise ..................................................................................................... 17 3.5.1 Projected Impacts .................................................................................................................................. 17 3.5.2 Sea Level Rise Data .............................................................................................................................. 17 3.1 Additional Hydrology Study Considerations ........................................................................................... 20 PART II – ALTERNATIVES CONCEPTUAL DESIGN ................................................................................................... 21 4. Conceptual Design Approach ........................................................................................................................... 21 4.1 Phasing .................................................................................................................................................. 21 4.2 Design Criteria and Assumptions ........................................................................................................... 21 4.2.1 Roadway Design Standards .................................................................................................................. 21 4.2.2 Climate Change and Sea Level Rise Adaptation ................................................................................... 25 4.3 Alternatives Considered but Eliminated from Further Consideration ..................................................... 26 5. Overview of Alternatives ................................................................................................................................... 27 6. Alternative 1 Conceptual Design ....................................................................................................................... 31 6.1 Phase 1 ................................................................................................................................................. 33 6.2 Alternative 1 Phase 2 Components ....................................................................................................... 39 6.3 Alternative 1 Phase 3 Components ....................................................................................................... 44 7. Alternative 2 Conceptual Design ....................................................................................................................... 46 7.1 Alternative 2 Phase 1 Components ....................................................................................................... 48 7.2 Alternative 2 Phase 2 Components ....................................................................................................... 48 7.3 Alternative 2 Phase 3 Components ....................................................................................................... 48 8. Alternative 3 Conceptual Design ....................................................................................................................... 51 8.1 Alternative 3 Phase 1 Components ....................................................................................................... 53 8.2 Alternative 3 Phase 2 Components ....................................................................................................... 53 8.3 Alternative 3 Phase 3 Components ....................................................................................................... 53 8.4 Conceptual Traffic Transition Plan ......................................................................................................... 55 Prepared for: Marin County Parks and Open Space District AECOM ǀ Carmen Ecological, Watershed Sciences, and Peter Baye Consulting i Draft Conceptual Design Report DRAFT Marin County Parks and Open Space District 9. Cost .................................................................................................................................................................. 56 10. Project Timeline and Phasing ........................................................................................................................... 58 PART III – OPPORTUNITIES AND CONSTRAINTS .................................................................................................... 60 11. Alternatives Analysis ......................................................................................................................................... 60 11.1 Methods ................................................................................................................................................. 61 11.2 Results ................................................................................................................................................... 62 11.3 Meeting Project Goals ........................................................................................................................... 65 12. Opportunities and Constraints ......................................................................................................................... 66 12.1 Costs and Timeline ................................................................................................................................ 66 12.1.1 Specific to Alternatives 1 ........................................................................................................................ 66 12.1.2 Specific to Alternatives 1 and 2 .............................................................................................................. 66 12.1.3 Specific to Alternatives 3 ........................................................................................................................ 67 12.2 Constructability/Complexity ................................................................................................................... 67 12.2.1 Roadways / Built Environment ............................................................................................................... 67 12.2.2