Como Creek Final Report Feb 2002

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See what the City of Coquitlam has in store for existing urban watersheds.

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  • D - 95

    City of Coquitlam

    Como Creek Integrated Stormwater Management Plan: Flood Risk Management and Watershed Restoration ":

    February 2002

    WO22002002VBC '

  • CITY OF COQUITLAM

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    II A B

    COMO CREEK INTEGRATED STORMWATER MANAGEMENT PLAN: FLOOD RISK MANAGEMENT AND WATERSHED RESTORATION

    PREPARED BY:

    CH2MHILL 920 - 475 West Georgia Street

    Vancouver, BC V6B 4M9 Te1.604 684-3282 I Fax. 604 684-3292

    February 2002

  • COMO CREEK INTEGRATED STORMWATER MANAGEMENT PLAN FINAL REPORT TABLE OF CONTENTS FEBRUARY 2002

    TABLE OF CONTENTS

    PAGE

    EXECUTIVE SUMMARY

    PART A . STRATEGY FOR FLOOD RELIEF AND HABITAT RESTORATION IN THE FRASER MILLS LOWLAND

    CHAPTER I

    CHAPTER 2

    CHAPTER 3

    CHAPTER 4

    CHAPTER 5

    INTRODUCTION 1.1 Background .................................................................................................. 1-1 1.2 Approach ............................. : ........................................................................ 1-1 1.4 Study Area .................................................................................................... 1-2 1.5 Project Issues ............................................................................................... 1-2 1.3 Deliverables .................................................................................................. 1-1

    PROBLEM IDENTIFICATION 2.1 Introduction ................................................................................................... 2-1 2.2 Overview of Previous Reports ...................................................................... 2-1 2.3 Nature of the Problem .................................................................................. 2-2 2.4 Recent Storm Events ................................................................................... 2-4 2.5 Summary of Findings ................................................................................... 2-4

    WATERSHED MODELLING

    3.2 Rainfall and Streamflow Data ....................................................................... 3-1 3.3 Modelling Approach ...................................................................................... 3-1

    3.1 Background .................................................................................................. 3-1

    3.4 Selection of Storm Events ............................................................................ 3-2 3.5 Results for December 1999 Storm ............................................................... 3-2 3.6 Results for January 1968 Storm ...................... : ............................................ 3-3 3.8 Future Modelling Applications ...................................................................... 3-3 3.9 Summary of Findings ................................................................................... 3-4

    4.1 Watershed Vision ......................................................................................... 4-1

    4.3 Hydraulic Control Elevations ........................................................................ 4-2 4.5 Integration with Uplands Strategy ................................................................ 4-3 4.6 Popeye Creek Stream Corridor Restoration ................................................ 4-3

    4.8 2001 Action Plan .......................................................................................... 4-4

    3.7 Lowering the GVRD Sewer .......................................................................... 3-3

    ELEMENTS OF AN INTEGRATED LOWLANDS PLAN

    4.2 Plan Elements for Flood Relief and Habitat Restoration .............................. 4-1 4.4 Flow Control at Trans-Canada Highway ...................................................... 4-3

    4.7 Capital Cost Estimates .................................................................................. 4-4

    INTEGRATION OF LOWLANDS AND UPLANDS STRATEGIES 5.1 Summary of Flood Mitigation for the Lowlands ............................................ 5-1 5.2 Land Use and Aquatic System Overview ..................................................... 5-1

    i CH2M HILL

  • COMO CREEK INTEGRATED STORMWAT~R MANAGEMENT PIAN FINAL REPORT TABLE OF CONTENTS FEBRUARY 2002

    PART B . STRATEGY FOR FLOOD RISK MANAGEMENT AND WATERSHED RESTORATION IN THE COMO UPLANDS

    CHAPTER 6

    CHAPTER 7

    CHAPTER 8

    CHAPTER 9

    CHAPTER 10

    MANAGEMENT'STRATEGY FOR THE COMO UPLANDS 6.1 Problem Statement ..................................................................................... 6-1 6.2 Identifying Solutions to the Erosion Problem .............................................. 6-3 6.3 Identifying Solutions to the Flooding Problem ............................................ 6-5 6.4 Summary of Findings .................................................................................. 6-6 LONG-TERM WATERSHED RESTORATION 7.1 The Water Balance Approach ...................................................................... 7-1 7.2 7.3

    Adaptive Approach to Watershed Retrofit ................................................. 7-2 Step 1 - Preliminary Targets for Rainfall Capture and Runoff Control ....... 7-3

    7.4. Step 2 -Validation of Preliminary Rainfall Capture and ............................ 7-8

    7.5 Steps 3 and 4 - Facilitating the Process of Change ..... ............................. 7-10 7.6 Steps 5 and 6 - Ongoing Assessment of the Watershed ........................... 7-11 7.7 Watercourse Restoration ............................................................................ 7-12

    Runoff Control Targets

    Retrofit Strategy

    7.8 Summary of Findings .................................................................................. 7-12 SHORT-TERM FLOOD RISK MANAGEMENT 8.1 8.2' 8.3 Culvert Upgrading and Bedload Interception .............................................. 8-4

    8.5 Summary of Findings .................. ; ............................................................... 8-9 ELEMENTS OF AN INTEGRATED PLAN FOR THE COMO UPLANDS 9.1 Description of Uplands Plan Elements ....................................................... 9-1 9.2 Plan Elements for Long-Term Watershed Restoration ............................... 9-1 9.3 Plan Elements for Short-Term Flood Risk Management ............................ 9-1

    Options for Flood Risk Management .......................................................... 8-1 Community Storage for Runoff Control ...................................................... 8-1

    8.4 Inter-Watershed Connections ..................................................................... 8-8

    CONCEPTS FOR RAINFALL CAPTURE AT.SOURCE 10.1 Performance Targets for Rainfall Capture ............................................... 10-1 10.2 Land Use Redevelopment Scenarios ...................................................... 10-2 10.3 Examples of Rainfall Capture Techniques .............................................. 10-8

    PART C . IMPLEMENTATION OF THE COMO CREEK WATERSHED MANAGEMENT PLAN

    CHAPTER 11 IMPLEMENTATION ACTIONS FOR COMO WATERSHED 1 1.1 Introduction ............................................................................................. 11-1 11.2 Summary of the Como Watershed Plan ................................................ 11-1 11.3 Description of Watershed Actions .......................................................... 11-3 11.4 Overall Costs of the Watershed Actions ................................................ 11-3 11.5 Financing the Watershed Management Plan ............ ............................ 11-4 11.6 Measuring Success ................................................................................ 11-4

    CHAPTER 12 CONCLUSIONS AND RECOMMENDATIONS 12.1 Conclusions ............................................................................................ 12-1 12.2 Recommendations .................................................................................. 12-2

    ii CHPM HILL

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    COMO CREEK INTEGRATED STORMWATER MANAGEMENT PLAN FINAL REPORT TABLE OF CONTENTS FEBRUARY 2002

    LIST OF TABLES Follows Page

    Table A

    Table 4-1

    Table 4-2

    Table 7-1

    Table 9-1

    Table 1 1-1

    Figure A

    Figure 1-1

    Figure 2-1 Figure 2-2 Figure 213

    Figure 3-1 Figure 3-2

    Figure 4-1 Figure 4-2

    Figure 4-3 Figure 4-4

    Figure 5-1 Figure 5-2

    Figure 6-1

    Figure 7-1 Figure 7-2 Figure 7-3 Figure 7-4 Figure 7-5

    Figure 7-6

    Implementation Actions for the Como Creek Watershed Management Plan ........ ES-2 Elements of an Integrated Plan for Flood Relief and Habitat Restoration ............. 4-2 In the Fraser Mills Lowlands

    2001 Action Plan Projects for Flood Relief and Flow Control in ............................ 4-5 Fraser Mills Lowlands

    Components of an Integrated Strategy for Managing the Complete ..................... 7-3 Spectrum of Rainfall

    Elements of an Integrated Plan for Flood Risk Management and Watershed ....... 9-1 Restoration in the Como Uplands

    Implementation Actions for the Como Creek Watershed Management Plan ........ 11-3

    LIST OF FIGURES

    Shared 50-Year Vision for Watershed Restoration

    Existing Watershed

    Problem Identification Potential for Flood Inundation Existing Control Points

    Levels of Modelling Intensity Duration Frequency Plots for Storm Events

    Concept for Surface Water Management in Fraser Mills Lowlands Elements of an Integrated Plan for Flood Relief and Habitat Restoration In the Fraser Mills Lowlands Proposed Control Elevations Schemati