TABLE OF CONTENTS Page Executive Summary 1.0 INTRODUCTION...1-1 1.1 Purpose of the Undertaking...1-1 1.2 Study Area Description...1-1 1.3 Description of the Undertaking...1-1 1.4 Rationale for the Undertaking...1-2 2.0 BACKGROUND...2-1 2.1 History of the Problem...2-1 2.2 Overview of Previous Studies...2-3 2.3 Conservation Authority Involvement Justification...2-5 2.4 Concurrent and Related Studies...2-8 3.0 PUBLIC AND AGENCY CONSULTATION...3-1 3.1 Consultation History...3-1 3.2 Public & Agency Notifications...3-1 3.3 Information Releases...3-2 3.4 Open Houses/Workshops...3-3 3.5 Community Liaison Committee...3-3 3.6 Technical Advisory Committee...3-4 3.7 Summary of Issues and Concerns...3-5 3.7.1 Public Information Centre No. 1 January 19, 2004...3-5 3.7.2 Public Information Centre No. 2 April 29, 2004...3-5 3.7.3 Public Information Centre No. 3 September 21, 2004...3-2 3.7.4 Mississaugas of New Credit First Nation...3-2 3.7.5 Ontario Mile Corporation Raceway...3-3 4.0 DESCRIPTION OF LOWER DON...4-1 4.1 The Don River Watershed...4-1 4.2 Lower Don River Flooding - A Historical Perspective...4-4 4.3 Physiographic Description...4-5 4.4 Baseline Studies...4-6 4.5 Hydrologic/Hydraulic Characterization...4-6 4.5.1 Hydrologic Analyses...4-6 4.5.2 Hydraulic Analysis...4-8 4.6 Aquatic Investigations...4-9 4.6.1 General...4-9 4.6.2 Fish Community Assessment...4-12 4.6.3 Water Temperature Survey...4-13 4.6.4 Benthic Invertebrate Sampling...4-13 4.6.5 Water Chemistry Monitoring...4-14 4.7 Terrestrial Natural Heritage...4-14 4.7.1 Terrestrial Attributes...4-14 4.7.2 Avian Migratory Stopover and Corridor Evaluation...4-16 4.8 Cultural Resources...4-16 4.8.1 Built Heritage...4-16 i
4.8.2 Archaeology...4-18 4.9 Socio-Economic & Land Use...4-19 4.9.1 Existing Land Use...4-19 4.9.2 Methodology...4-22 4.9.3 Flood Damage Assessment...4-23 4.10 Topography, Soils, Groundwater and Soil Contamination...4-24 4.11 Existing Infrastructure...4-25 4.11.1 Utility Lines...4-25 4.11.2 Rail Infrastructure...4-25 5.0 EXAMINATION OF ALTERNATIVES...5-1 5.1 Approach Overview......5-1 5.2 Description of Long List of Alternatives...5-1 5.2.1 Do Nothing...5-1 5.2.2 Flood Policy Revision...5-1 5.2.3 Flood Protection Landform with East Bank Works & Culvert...5-2 5.2.4 Flood Protection Landform with East Bank Works (No culvert)...5-3 5.2.5 Wedge with East Bank Works &Culvert...5-4 5.2.6 Wedge & East Bank Works...5-4 5.2.7 CN Rail Bridge & Channel Widening...5-4 5.2.8 Secondary Channel with Flood Protection Landform...5-5 5.2.9 Floodwall/Dyke...5-6 5.2.10 Upstream Storage...5-6 5.2.11 Floodproofing of Individual Structures...5-7 5.2.12 River Dredging...5-7 5.2.13 Watershed Conservation Measures...5-8 5.3 Screening of Alternatives......5-8 5.4 Evaluation of Alternatives and Selection of Preferred Alternative...5-15 5.4.1 Physical Assessment Group...5-15 5.4.2 Biological Assessment Group...5-29 5.4.3 Cultural Assessment Group...5-29 5.4.4 Socio-Economic Assessment Group...5-30 5.4.5 Engineering/Technical Assessment Group...5-31 5.4.6 Cost Assessment Group...5-31 5.4.7 Comparative Evaluation...5-33 5.4.8 Summary of Evaluation...5-35 6.0 FUNCTIONAL DESIGN & ENVIRONMENTAL ASSESSMENT...6-1 6.1 General...6-1 6.2 Refinement of the Preferred Alternative...6-1 6.2.1 Hydro One Networks Plant...6-1 6.2.2 Geo-Environmental/Geotechnical Investigations...6-3 6.2.3 Bridge Extension Option for Additional Hydraulic Capacity (Selected as Preferred Option)...6-9 6.3 Project Description...6-9 6.4 Design Requirements for the Flood Protection Landform...6-9 6.4.1 Provincial Context...6-9 6.4.2 Details of the Flood Protection Landform...6-13 6.4.3 Grading Considerations...6-17 6.4.4 Landform Composition...6-18 6.4.5 Construction Considerations...6-19 6.4.6 Traffic Effects...6-19 ii
6.4.7 Stormwater Management...6-20 6.4.8 Utility Relocation...6-20 6.4.9 Integration with West Don Lands Precinct Plan...6-23 6.5 Details of the Remedial Works at the CN Rail Embankment...6-24 6.5.1 General...6-24 6.5.2 Multi-Cell Culvert Option...6-24 6.5.3 Bridge Extension Option...6-36 6.5.4 Identification of Preferred Option (Bridge Extension) for the CN Rail Embankment...6-40 6.6 East Bank Retaining Wall/Dykes...6-45 6.7 Keating Channel Dredging...6-47 6.8 Modifications to the Enbridge Utility Bridge...6-48 6.9 Cost...6-49 6.10 Assessment of Effects and Benefits...6-50 6.10.1 Physical Environment...6-50 6.10.2 Biological...6-77 6.10.3 Cultural...6-78 6.10.4 Land Use/Socio-Economic...6-80 6.10.5 Engineering/Technical...6-82 6.11 Mitigation Strategy...6-83 6.12 Project Monitoring...6-83 6.12.1 Construction Monitoring...6-83 6.12.2 Operation Monitoring...6-83 6.13 Landscape Plan...6-87 6.13.1 Planting Zones...6-87 6.13.2 Demonstration Plan...6-92 6.14 Pedestrian Circulation and Access...6-93 7.0 SUMMARY OF FINDINGS & CONCLUSIONS...7-1 7.1 Preferred Remedial Flood Protection Alternative...7-1 7.2 Baseline Inventories...7-2 7.3 Environmental Effects of the Flood Remediation Project...7-2 7.4 Mitigation Plan...7-3 7.5 Final Design & Implementation Considerations...7-3 7.6 Other Considerations...7-5 Bibliography iii
List of Tables Table 4.1 - Summary of Summary of Calculated Peak Flows (Future Land Use)...4-7 Table 4.2 - Comparison of Calculated Flows Hurricane Hazel...4-8 Table 4.3 - Regulatory Flood Levels Along the Lower Don River...4-9 Table 4.4 - Classification of Fish Captured in the Lower Don River...4-12 Table 4.5 - Existing Land Use in Spill Zone 3...4-19 Table 4.6 - Industrial/Commercial/Industrial Flood Damage Values...4-23 Table 4.7 - Flood Damages by Primary Land Use...4-24 Table 4.8 - Study Area Utilities...4-26 Table 5.1 - Screening the Long List of Alternatives...5-10 Table 5.2 - Comparative Evaluation of Alternatives...5-16 Table 5.3 - Ranking of Alternatives...5-26 Table 5.4 - Summary of Alternatives Ranking by Criteria Group...5-34 Table 6.1 - Calculated Hydraulic Conditions for the Regulatory Flood...6-29 Table 6.2 - Weekend Delays to Via Rail Service (No Track Diversion)...6-34 Table 6.3 - Summary of Construction Work Blocks & Associated Impacts on Train Operations for Multi-cell Culvert Option (No Track Diversion)...6-35 Table 6.4 - Preliminary Cost Estimate for Multi-Cell Culvert Option...6-37 Table 6.5 - Construction Sequencing & Time Requirements for Installation of the Bridge Extension Option...6-41 Table 6.6 - Preliminary Cost Estimate for the Bridge Extension Option...6-42 Table 6.7 - Summary of Option Evaluation...6-45 Table 6.8 - Summary of Preliminary Costs...6-49 Table 6.9 - Summary of Effects...6-51 Table 6.10 - Description of Potential Effects...6-54 Table 6.11 - Summary of Mitigation Strategies...6-84 Table 6.12 - Flood Protection Landform Vegetation Zones...6-87 List of Figures Figure 1.1 - Study Area...1-1 Figure 1.2 - -Component Works...1-2 Figure 2.1 - Regulatory Floodplain along the Lower Don River...2-3 Figure 2.2 - Floodwater Depths along the Lower Don River for the Regulatory Flood...2-6 Figure 4.1 - Existing Land Use in the Don River Watershed...4-2 Figure 4.2 - Future Land Use in the Don River Watershed...4-3 Figure 4.3 - Extent of Flooding in the Lower Don River During a Hurricane Hazel Event...4-10 Figure 4.4 - Water Surface Profile Existing Conditions...4-11 Figure 4.5 - Seasonal Distribution of Fish Species in the Lower Don River...4-13 Figure 4.6 - Terrestrial Natural Heritage Study Area and Community Ranks...4-14 Figure 4.7 - Avian Migratory Stopover Evaluation Stations...4-16 Figure 4.8 - Heritage Resources South and East of the Lower Don River...4-17 Figure 4.8 - Existing Land Use...4-20 Figure 4.9 - Official Plan Designation in Spill Zone 3...4-21 Figure 4.10 - Flood Depths in Spill Zone 3...4-22 iv
Figure 5.1 - Flood Protection Landform with Culvert & East Bank Works...5-2 Figure 5.2 - Flood Protection Landform & East Bank Works...5-4 Figure 5.3 - Wedge with Culvert & East Bank Works...5-4 Figure 5.4 - Wedge & East Bank Works...5-5 Figure 5.5 - Secondary Channel with Flood Protection Landform...5-5 Figure 5.6 - Existing & Potential Storage Sites...5-6 Figure 5.7 - Extent of River Dredging...5-7 Figure 6.1 - Location of Hydro One Plant...6-2 Figure 6.2 - Location Plan of Geo Environmental/Geotechnical Investigations...6-5 Figure 6.3 - Generalized Stratigraphy...6-6 Figure 6.4 -, Component Works...6-10 Figure 6.5 - Flood Protection Landform Plan...6-14 Figure 6.6A - Flood Protection Landform Cross-Sections...6-15 Figure 6.6B - Flood Protection Landform Cross-Sections...6-16 Figure 6.7 - Utilities...6-21 Figure 6.8 - CN Rail Crossing of Lower Don River...6-25 Figure 6.9 - General Arrangement Culvert Option at CN Rail Crossing...6-26 Figure 6.10 - Plan Culvert Option at CN Rail Crossing...6-27 Figure 6.11 - HEC-2 Cross Section Numbers & Location...6-30 Figure 6.12 - Construction Staging...6-33 Figure 6.13 - General Arrangement Bridge Option at CN Rail Crossing...6-38 Figure 6.14 - Plan-Bridge Option at CN Rail Crossing (21.3 m Span)...6-39 Figure 6.15 - Remedial Flood Works for the East Bank...6-46 Figure 6.16 - Flooding Depths with in Place...6-75 Figure 6.17 - Flood Protection Landform Vegetation Zones...6-88 Figure 6.18 - Flood Protection Landform Vegetation Zones (Section View)...6-88 Figure 6.19 - Demonstration Plan...6-92 Figure 6.20 - Demonstration Plan (Section View)...6-93 Figure 6.21 - Potential Trail Concept Plan...6-93 List of Appendices Appendix A... Public Information Centre Material Appendix B... Mississaugas of the New Credit Appendix C...Correspondence with Stakeholders Appendix D... Hydraulic Modelling Details Appendix E...Aquatic Investigations Appendix F... Terrestrial Natural Heritage Appendix G...Cultural Heritage Appendix H...Geo-Environmental Study Appendix I... Rail Transportation Study Appendix J... Geo-Environmental and Geotechnical Field Investigations Appendix K...Report on Alternatives for the East Bank v