COLUMBIA SHUSWAP REGIONAL DISTRICT Geohazard Risk Prioritization FINAL April 16, 2020 Project No.: 1899001 Prepared by BGC Engineering Inc. for: Columbia Shuswap Regional District BGC ENGINEERING INC. 500-980 Howe Street, Vancouver, BC Canada V6Z 0C8 Tel: 604.684.5900 Fax: 604.684.5909 BGC ENGINEERING INC. AN APPLIED EARTH SCIENCES COMPANY Suite 500 - 980 Howe Street Vancouver, BC Canada V6Z 0C8 Telephone (604) 684-5900 Fax (604) 684-5909 April 16, 2020 Project No.: 1899001 Jan Thingsted, Planner Columbia Shuswap Regional District 555 Harbourfront Drive NE PO Box 978 Salmon Arm, BC V1E 4P1 Dear Mr. Thingsted, Re: Geohazard Risk Prioritization – FINAL BGC is pleased to provide you with the following geohazard risk prioritization for the Columbia- Shuswap Regional District. The web application accompanying this report can be accessed at www.cambiocommunities.ca. Those without a username and password should click “Register for Access”. Should you have any questions, please do not hesitate to contact the undersigned. We appreciate the opportunity to collaborate with you on this challenging and interesting study. Yours sincerely, BGC ENGINEERING INC. per: Sarah Kimball, M.A.Sc., P.Eng., P.Geo. Senior Geological Engineer Columbia Shuswap Regional District April 16, 2020 Geohazard Risk Prioritization - FINAL Project No.: 1899001 TABLE OF REVISIONS ISSUE DATE REV REMARKS DRAFT March 10, 2020 Original issue FINAL April 16, 2020 Original issue CREDITS AND ACKNOWLEDGEMENTS BGC would like to express gratitude to the Columbia Shuswap Regional District for providing background information, guidance and support throughout this project. Key CSRD staff providing leadership and support included: • Jan Thingsted, Planner • David Major, IT/GIS Coordinator • Tom Hansen, Emergency Program Coordinator • Derek Sutherland, Manager of Protective Services • Gerald Christie, Manager Development Services • Corey Paiement, Team Leader, Planning Services. The following BGC personnel were part of the study team: • Kris Holm (Project Director) • Sarah Kimball (Project Manager) • Richard Carter • Matthew Buchanan • Matthieu Sturzenegger • Elisa Scordo • Patrick Grover • Philip LeSueur • Midori Telles-Langdon • Alistair Beck. BGC ENGINEERING INC. Page i Columbia Shuswap Regional District April 16, 2020 Geohazard Risk Prioritization - FINAL Project No.: 1899001 LIMITATIONS BGC Engineering Inc. (BGC) prepared this document for the account of Columbia Shuswap Regional District. The material in it reflects the judgment of BGC staff in light of the information available to BGC at the time of document preparation. Any use which a third party makes of this document or any reliance on decisions to be based on it is the responsibility of such third parties. BGC accepts no responsibility for damages, if any, suffered by any third party as a result of decisions made or actions based on this document. As a mutual protection to our client, the public, and ourselves, all documents and drawings are submitted for the confidential information of our client for a specific project. Authorization for any use and/or publication of this document or any data, statements, conclusions or abstracts from or regarding our documents and drawings, through any form of print or electronic media, including without limitation, posting or reproduction of same on any website, is reserved pending BGC’s written approval. A record copy of this document is on file at BGC. That copy takes precedence over any other copy or reproduction of this document. BGC ENGINEERING INC. Page ii Columbia Shuswap Regional District April 16, 2020 Geohazard Risk Prioritization - FINAL Project No.: 1899001 EXECUTIVE SUMMARY The Columbia Shuswap Regional District (CSRD, the Regional District) retained BGC Engineering Inc. (BGC) to carry out a geohazard risk prioritization study (the regional study) for the Regional District. The primary objective of this study is to characterize and prioritize flood and steep creek (debris-flood and debris-flow) geohazards in the CSRD that might impact developed properties. Collectively these are referred to as “geohazards” in this document. While the study encompasses both electoral areas and municipalities, BGC was retained to complete prioritization from the perspective of CSRD (not individual municipalities). The goal is to support decisions that prevent or reduce injury or loss of life, environmental damage, and economic loss due to geohazard events. Completion of this risk prioritization study is a step towards this goal. The regional study provides the following outcomes across the CSRD: • Identification and prioritization of geohazard areas, from the perspective of CSRD, based on the principles of risk assessment (i.e., consideration of both hazards and consequences) • Geospatial information management for both geohazard areas and elements at risk • Web communication tool to view prioritized geohazard areas and supporting information • Discussion of the relative sensitivity of geohazard areas to climate change • Information gap identification and recommendations for further study. These outcomes support CSRD to: • Continue operating under existing flood-related policies and bylaws, but based on improved geohazard information and information management tools • Review and potentially develop Official Community Plans (OCPs) and related policies, bylaws, and land use and emergency management plans • Undertake flood resiliency planning, which speaks to the ability of an area “to prepare and plan for, [resist], recover from, and more successfully adapt to adverse events” (NRC, 2012) • Develop a framework for geohazard risk management, including detailed hazard mapping, risk assessment, and mitigation planning • Prepare funding applications to undertake additional work related to geohazard risk management within the CSRD. This study provides results in several ways: • This report summarizes methods and results, with additional details in appendices. • Access to Cambio web application displaying prioritized geohazard areas and supporting information. This application represents the easiest way to interact with study results. Appendix B provides a guide to navigate Cambio Communities. • Geodatabase with prioritized geohazard areas. • Excel spreadsheet with attributes of prioritized geohazard areas. BGC ENGINEERING INC. Page iii Columbia Shuswap Regional District April 16, 2020 Geohazard Risk Prioritization - FINAL Project No.: 1899001 In total, BGC identified and prioritized 1446 geohazard areas encompassing over 1946 km2 of the CSRD (Table E-1, Figure E-1). Table E-1. Number of prioritized areas in the CSRD, by geohazard type. Priority Level Grand Geohazard Type Very Very High Moderate Low Total High Low Clear-Water Floods 0 58 92 846 0 996 (water courses and water bodies) Steep Creeks (Fans) 11 120 104 166 49 450 Grand Total (Count) 11 178 196 1012 49 1446 Grand Total (%) 1% 12% 14% 70% 3% 100% Table E-3 highlights clear-water flood and steep creek geohazard areas considered high priority for further assessment. The full list of prioritized areas should be reviewed for decision making. BGC emphasizes that the baseline priority ratings are not equivalent to an absolute level of risk, and CSRD will need to consider additional factors in decisions about next steps at any site (i.e., evaluation of costs and benefits to advance the steps of risk management). Table E-2 lists the results worksheets, which are provided in Appendix H. These worksheets can be filtered and sorted to view ranked hazard areas by any field in the worksheets. When reviewing results, local authorities may wish to consider other factors outside the scope of this assessment but that also affect risk management decision making. For example, additional factors include the level of risk reduction already achieved by existing structural mitigation (dikes), the level of flood resiliency in different areas, and comparison of the risk reduction benefit to the cost of new or upgraded flood risk reduction measures. Appendix F provides the example Risk Assessment Information Template (RAIT) form required by the National Disaster Mitigation Program (NDMP). Table E-2. Results worksheets provided in Appendix H. Appendix H Contents (Excel Worksheet Name) Study Area Metrics Summary statistics of select elements at risk (count of presence in geohazard areas). Study Area Hazard Summary Summary statistics of elements at risk, according to their presence in geohazard areas. Study Area Hazard Type Summary Summary statistics of geohazard areas, according to the presence of elements at risk. Priority by Jurisdiction Summary statistics of prioritization results by jurisdiction. Steep Creek Hazard Attributes Attributes for all steep creek geohazard areas. Clear-water Flood Hazard Attributes Attributes for all clear-water flood geohazard areas. BGC ENGINEERING INC. Page iv Columbia Shuswap Regional District April 16, 2020 Geohazard Risk Prioritization - FINAL Project No.: 1899001 Figure E-1. Number of prioritized areas in each jurisdiction within the CSRD BGC ENGINEERING INC. Page v Columbia Shuswap Regional District April 16, 2020 Geohazard Risk Prioritization - FINAL Project No.: 1899001 Table E-3. Geohazard areas highlighted as high priority for more detailed assessment. Hazard Code Hazard Type Geohazard Process Name Geohazard Rating Consequence Rating Priority Rating 9291 / 9301 / 9302 / 9299 Clear-water Flood Shuswap Lake Moderate Very High High 9142 / 9305 / 9285 / 9281 / 9183 Clear-water Flood Eagle River Moderate Very High High