River Mile 13.5 Sediment Isolation Cap Construction Completion Report River Mile 13.5 Lower Willamette River Portland, Oregon April 29, 2016 Prepared for: Portland General Electric Company 121 SW Salmon Street Portland, Oregon 97204 Prepared by: 1501 4th Ave, Suite 1400 Seattle, Washington 98101 Job No. 60439278 CONTENTS 1.0 Introduction ...................................................................................................................................... 1-1 1.1 Site Conditions ................................................................................................................................... 1-1 1.2 Background Information ..................................................................................................................... 1-1 1.3 Approvals and Permits ....................................................................................................................... 1-2 1.4 Project Team and Roles and Responsibilities .................................................................................... 1-3 2.0 Remedial Design............................................................................................................................... 2-1 2.1 Debris Removal .................................................................................................................................. 2-1 2.2 Isolation Cap....................................................................................................................................... 2-1 2.3 Armor Stone ....................................................................................................................................... 2-2 3.0 Pre-Construction Activities ............................................................................................................. 3-1 3.1 Health and Safety ............................................................................................................................... 3-1 3.2 Baseline Environmental Monitoring and Engineering Controls ........................................................... 3-1 3.2.1 Baseline Turbidity Monitoring ........................................................................................... 3-1 3.2.2 Baseline Noise Monitoring ................................................................................................ 3-2 3.2.3 Baseline Dust Monitoring .................................................................................................. 3-2 3.2.4 Floating Debris Boom ....................................................................................................... 3-2 3.3 Equipment Mobilization ...................................................................................................................... 3-2 3.4 Debris Removal, Sampling, and Disposal ........................................................................................... 3-2 3.5 Post Debris Removal Bathymetric Survey .......................................................................................... 3-3 4.0 Construction Activities .................................................................................................................... 4-1 4.1 Fill Material Verification ...................................................................................................................... 4-1 4.1.1 Isolation Cap Sand Layer Material .................................................................................... 4-1 4.1.2 Armor Stone Material ........................................................................................................ 4-1 4.2 Isolation Sand Layer Construction ...................................................................................................... 4-2 4.2.1 Placement Methods .......................................................................................................... 4-2 4.2.2 Placement Sequence ....................................................................................................... 4-2 4.2.3 Final Confirmation Bathymetric Survey............................................................................. 4-3 4.2.4 Deviations from Remedial Design .................................................................................... 4-4 4.3 Armor Layer Construction ................................................................................................................... 4-5 4.3.1 Placement Methods .......................................................................................................... 4-5 4.3.2 Placement Sequence ....................................................................................................... 4-5 4.3.3 Final Confirmation Bathymetric Survey............................................................................. 4-6 4.3.4 Deviations from Remedial Design .................................................................................... 4-6 4.4 Final Diver Inspection ......................................................................................................................... 4-8 4.5 Demobilization .................................................................................................................................... 4-8 4.6 Environmental Monitoring ................................................................................................................... 4-8 i CONTENTS 4.6.1 Turbidity Monitoring .......................................................................................................... 4-8 4.6.2 Noise Monitoring ............................................................................................................... 4-9 4.6.3 Dust Monitoring ................................................................................................................ 4-9 4.7 Archaeological Observations ............................................................................................................ 4-10 4.8 Health and Safety ............................................................................................................................. 4-10 4.9 Best Management Practices ............................................................................................................. 4-10 4.10 Sustainable Remedial Practices ....................................................................................................... 4-10 4.11 Utilities and Easements .................................................................................................................... 4-11 4.12 Survey Control .................................................................................................................................. 4-11 5.0 Long-Term Monitoring ..................................................................................................................... 5-1 6.0 Certification Statement .................................................................................................................... 6-1 7.0 References ........................................................................................................................................ 7-1 ii CONTENTS TABLES Table 1-1 RM 13.5 Feasibility Study SWAC Analysis Table 1-2 RM 13.5 Remedial Action Objectives and Remedial Goals Table 4-1 Sediment Isolation Cap Chronology Table 4-2 Fill Material Volume Summary Table 4-3 Environmental Monitoring Summary FIGURES Figure 1-1 Site Location Map Figure 2-1 Proposed Sediment Isolation Cap Extent Figure 3-1 Environmental Monitoring Locations Figure 3-2 Post Debris Removal Elevation (Pre-cap) Figure 4-1 Placement Grid Cell Layout Figure 4-2 Isolation Sand Layer Placement Pictures Figure 4-3 Final Isolation Sand Layer Thickness Figure 4-4 Final As-Built Sand Isolation Layer Slope Figure 4-5 Armor Layer Placement Pictures Figure 4-6 Final Armor Layer Thickness Figure 4-7 Final As-Built Armor Layer Slope Figure 4-8 Final Bathymetric Contours (Post-capping) and Shoreline Habitat Shelf APPENDICES Appendix A Permits Appendix B Daily Field Reports Appendix C As-Built Drawings Appendix D Turbidity Monitoring Data Appendix E Noise Monitoring Data Appendix F Dust Monitoring Data Appendix G Debris Disposal Data Appendix H Post Debris Removal Survey Data Appendix I DEQ Correspondence Appendix J Armor Stone Gradation Results Appendix K Response to DEQ’s Comments on the RM 13.5 Installed Armor Stone Size Appendix L Sediment Core Information Appendix M Final Sand Layer Survey Data Appendix N Final Armor Layer Survey Data Appendix O Wash Water Analytical and Disposal Appendix P HME Letter of Certification iii ACRONYMS AND ABBREVIATIONS BDS Bureau of Development Services BES Bureau of Environmental Services BMP best management practice CCR Construction Completion Report City City of Portland COPC contaminant of potential concern COPD City of Portland Datum Corps U.S. Army Corps of Engineers cy cubic yard(s) dB decibel(s) DDD dichlorodiphenyldichloro-ethane DDE dichlorodiphenyldichloro-ethylene DDT dichlorodiphenyltrichloro-ethane DDx sum of DDD, DDE, and DDT DEQ [Oregon] Department of Environmental Quality DFR daily field report DSL [Oregon] Department of State Lands ESA Endangered Species Act FS Feasibility Study ft2 square foot/feet FWS [U.S.] Fish and Wildlife Service HASP Health and Safety Plan HME HME Construction, Inc. IDP Inadvertent Discovery Plan mg/m3 milligrams per cubic meter MUBC mean upriver background concentration NAD North American Datum NAVD North American Vertical Datum NHPA National Historic Preservation