A Community of Communities
REQUEST FOR PROPOSAL
CBRM_P18-2020
PRIME BROOK FLOODPLAIN DELINEATION & WATERCOURSE CROSSING CONDITION ASSESSMENTS
Closing: THURSDAY, OCTOBER 15, 2020 at 3:00 pm local time
Cape Breton Regional Municipality Procurement Section Suite 102, 1st Floor 320 Esplanade Sydney, NS B1P 7B9
Cape Breton Regional Municipality PROCUREMENT SECTION, FINANCIAL SERVICES 320 ESPLANADE, SUITE 102 SYDNEY,NS B1P 7B9 PHONE: 902-563-5015 EMAIL: [email protected]
MANDATORY REQUIREMENT CHECK LIST
PRIOR TO SUBMISSION PLEASE CHECK THAT YOU HAVE SUBMITTED A COPY OF THE FOLLOWING DOCUMENTS
□ SCHEDULE “A” – MUNICIPAL BY-LAW COMPLIANCE CERTIFICATE
□ SCHEDULE “B” – TRADE AGREEMENTS ACKNOWLEDGEMENT
□ DUE TO COVID-19 PRECAUTIONS, SUBMISSIONS FOR THIS TENDER WILL ONLY BE ACCEPTED BY EMAIL TO [email protected] & MUST INCLUDE ALL ITEMS LISTED UNDER THIS CHECK LIST
□ THIS IS A TWO (2) ENVELOPE SUBMISSION. DUE TO THE ABOVE WE REQUEST YOU ATTACH TWO (2) SEPARATE PDF’S, ONE TITLED TECHNICAL AND ONE TITLED COSTING. THE PROCUREMENT DEPARTMENT WILL HOLD THE COSTING SUBMISSIONS UNTIL THE USER DEPARTMENT HAS COMPLETED THE EVALUATIONS OF THE TECHNICAL SUBMISSIONS. (RECTIFICATION PERIOD DOES NOT APPLY)
□ RECEIVED ADDENDA NO. _____ TO NO._____ INCLUSIVE WERE CAREFULLY EXAMINED
DATED THIS ______DAY OF ______, 2020. COMPANY NAME: ______ADDRESS: ______CITY/ PROVINCE: ______POSTAL CODE: ______PHONE NO.: ______FAX NO.: ______EMAIL ADDRESS: ______WEBSITE: ______
CONTACT NAME(please print):______
TITLE (please print): ______PHONE NO.:______
THE FOLLOWING INFORMATION MUST BE COMPLETED TO ENSURE ACCEPTANCE. FAILURE TO COMPLY WITH ABOVE WILL RESULT IN DISQUALIFICATION OF YOUR BID.
Cape Breton Regional Municipality PROCUREMENT SECTION, FINANCIAL SERVICES 320 ESPLANADE, SUITE 102 SYDNEY,NS B1P 7B9 PHONE: 902-563-5015 EMAIL: [email protected]
INSTRUCTIONS TO BIDDERS
REQUEST FOR PROPOSAL PRIME BROOK FLOODPLAIN DELINEATION & WATERCOURSE CROSSING CONDITION ASSESSMENTS
Closing: Submit to the undersigned up to 3:00 P.M., THURSDAY, OCTOBER 15, 2020, the bid must be returned in a sealed envelope in TRIPLICATE (3) COPIES and must clearly designate CBRM_P18-2020 to the Procurement Section, Financial Services Suite 102, 320 Esplanade, Sydney, N. S. B1P 7B9. NOTE: FAXED / ELECTRONIC submissions are NOT acceptable and will not be considered
Questions & Clarifications: Any clarification required by a proponent must be requested in writing to the responsible Buyer indicated in the Solicitation. Such requests must be provided in due time before the closing date in order to allow proper consideration and a reply. The response to a request for clarifications submitted by any Proponent will be posted on the Nova Scotia Government Website as an Addendum.
Withdrawal or Modification of Bid: Proponents may withdraw, replace or modify their bid up until the specified closing time, provided that this is done in writing. Any modification or replacement of a bid must be done in the same format as defined in the Solicitation. NOTE: FAXED / ELECTRONIC modifications are acceptable
Addenda: All addenda must be acknowledged in bid submission; proponents must monitor the Nova Scotia Government Tenders Website for any addenda that may be issued. CBRM staff no longer maintains plan takers lists, and no longer have knowledge of who has downloaded opportunities. http://www.novascotia.ca/tenders/tenders/ns-tenders.aspx
Rectification Period: Procurement opens and reviews the Bids to determine if all mandatory submission requirements have been met in accordance with the Solicitation Document. If the bid fails to meet the mandatory submission requirements, Procurement will notify the Bidders that there is a second opportunity to meet the mandatory submission requirements within the rectification period of two business days. Once the rectification period deadline passes, Bids still failing to meet the mandatory submission requirements are disqualified and will not be evaluated further. All bids satisfying the mandatory submission requirements are then passed along to the evaluation team for further evaluation. Exceptions to this are technical addenda, if a technical addendum is not acknowledged, the Bidder will be disqualified and there is no rectification allowance for incorrect submittal of a two envelope submission (two PDFs due to Covid-19).
Tenders requiring bid deposit: If a tender requires a non-refundable bid deposit only those companies who have complied with this request will be considered for acceptance.
TENDER CONTENTS: (Section Applies to: Construction Contracts, Services & Sale of Municipal Property ONLY!)
Bid Security: Each tender must be accompanied by a certified cheque payable to the Cape Breton Regional Municipality or a Bid Bond on CCDC Form 220 for ten (10) percent of the tendered sum. Any withdrawal of the successful tender shall constitute forfeiture of the bid deposit.
Performance Security: A Performance Bond in the amount of fifty (50) percent contract price and Labour and Material Payment Bond in the amount of fifty (50) percent of the contract price will be required upon notification of award and before the signing date of the contract or issue of the Purchase Order.
Cape Breton Regional Municipality PROCUREMENT SECTION, FINANCIAL SERVICES 320 ESPLANADE, SUITE 102 SYDNEY,NS B1P 7B9 PHONE: 902-563-5015 EMAIL: [email protected]
Alternate Securities Acceptable: As an alternate to the Security Deposit and the Consent of Surety requirements stated herein, Contractors may submit a ten (10) percent bid security certified cheque, and subsequently upon notification of award, an additional ten (10) percent contract security certified cheque, in lieu of contract stated bonding.
Accompanying Documents: All bids must include the following documents: - “Check List” Completed in full /Signed /Dated(Including acknowledgement of addenda) - The signed Schedule “A” Municipal By-Law Compliance form attached to the tender documents. - A letter of Good Standing/Clearance from the Workers’ Compensation Board of Nova Scotia - Proof of current and valid Workplace Safety Certificate of Recognition(COR) from an authorized institution(East Coast Mobile Medical, HSE Integrated Limited, Nova Scotia Construction Safety Association (NSCSA), Nova Scotia Trucking Safety Association, Occupational Health and Educational; Services 2002 Inc, Safety Services Nova Scotia or equivalent) - Completed/signed Appendix “A” Consultant, Contractor, Supplier Health & Safety Questionnaire. - General liability insurance. Prior to Contract Award – In accordance with section nine (9) of the CBRM Procurement Policy, the successful tenderer may be required to provide an approved Commercial Property Zoning Confirmation, issued by CBRM’s Development Officer, prior to award of contract.
Following completion of the tendered work, letters of clearance from both organizations, dated no earlier than the final day worked on the project, must be submitted with the final invoice for the project. This will form a condition of the tender in addition to any other conditions within the contract documents and specifications. POLICY:
• Canadian Free Trade Agreement (CFTA), Atlantic Procurement Agreement (APA) and The Cape Breton Regional Municipality Procurement Policy are the governing documents used for all tenders. Copies of these documents are available from the Financial Services Department, Procurement Section, Suite 102, 320 Esplanade Sydney, N.S. or by phoning (902) 563-5015
• Successful bidder will be required to follow CBRM protocol as designated by Purchasing Department for delivery and invoicing.
• Payment: Any supplier having an account due to the Cape Breton Regional Municipality, which is in arrears, will have such arrears deducted from payments being made to the supplier.
The Cape Breton Regional Municipality reserves the right to reject any or all tenders or to accept any tender or part thereof considered to be in its best interest.
Emily Neville Emily Neville Procurement Officer Financial Services
Cape Breton Regional Municipality PROCUREMENT SECTION, FINANCIAL SERVICES 320 ESPLANADE, SUITE 102 SYDNEY,NS B1P 7B9 PHONE: 902-563-5015 EMAIL: [email protected]
SCHEDULE “A”
MUNICIPAL BY-LAW COMPLIANCE CERTIFICATE
This document forms part of and is incorporated in to the Tender. Bidders convicted of violations of any Cape Breton Regional Municipal By-Laws or found in contravention of the Dangerous and Unsightly Provision of the Municipal Government Act, S.N.S. 1998, c. 18 shall be precluded from bidding on the tender. Successful bidders who subsequently are found guilty of violation of any Cape Breton Regional Municipal By-Laws or are found to have contravened the Dangerous and Unsightly Provision of the Municipal Government Act S.N.S. 1998, c. 18 shall have the tenders revoked and shall be precluded from bidding on subsequent tenders for a period of thirty-six months.
______(hereinafter referred to as “The Bidder”) does hereby certify that the Bidder has not been found guilty of violation of any Cape Breton Regional Municipal By-Laws and has not been found to have contravened the Dangerous and Unsightly Provision of the Municipal Government Act S.N.S. 1998, c. 18 and furthermore hereby agrees to comply with all Cape Breton Regional Municipal By-Laws and the Dangerous and Unsightly provision of the Municipal Government Act, S.N.S. 1998, c. 18. The Bidder understands and agrees that any finding of guilt or contravention of any Cape Breton Regional Municipal By-Laws and provisions will result in the Tender being revoked and the Bidder being precluded from bidding on any subsequent Tender for a period of thirty-six months.
______Witness Bidder
CBRM INTERNAL USE ONLY
Approved by: ______
Title: ______
Date: ______
Cape Breton Regional Municipality PROCUREMENT SECTION, FINANCIAL SERVICES 320 ESPLANADE, SUITE 102 SYDNEY,NS B1P 7B9 PHONE: 902-563-5015 EMAIL: [email protected]
SCHEDULE “B”
TRADE AGREEMENTS ACKNOWLEDGEMENT
All Public Sector Entities in Nova Scotia have trade agreement obligations under the Public Procurement Act. Trade agreements play a vital role in our economy. They create market access for our goods and services by reducing barriers to, among other things, labour mobility, investments, energy, agriculture, and government procurement. Agreements can be comprehensive, covering a number of different issues, or more concentrated, covering individual issues. Each agreement has unique language, exemptions, rules, and requirements.
Municipalities, Academic Institutions, School Boards, Health Authorities (MASH) and Crown Corporations that have their own procurement groups and policies must ensure they are consistent with the principles of the Province of Nova Scotia Procurement Policy, and the obligations of the Public Procurement Act.
Trade Agreements that impact government procurement in Nova Scotia include the Canadian Free Trade Agreement (CFTA) and the Comprehensive Economic Trade Agreement with the European Union (CETA). The CFTA and CETA includes all provinces, Northwest Territories, Yukon, and the Federal Government as well as their respective MASH sectors and Crown Corporations.
The key to being compliant with multiple trade agreements is to ensure you are meeting the obligations of the one with the lowest thresholds, which in this case is the CFTA. Table A outlines the thresholds for these two agreements.
TABLE A – Domestic Agreement
Agreement Coverage MASH Canadian Free Trade Agreement Equal access to Canadian suppliers. Goods: $105,700+ Includes all CDN Provinces, NWT, Services: $105,700+ YUK, their respective MASH Construction: 264,200+ and Crowns, and the Federal Government Comprehensive Economic Trade Equal access to EU suppliers – Goods: $365,700+ Agreement with the European includes: Federal Government, Services: $365,700+ Union Provinces, Territories, MASH, Construction: $9.1M+ Provincial/Federal Crowns & Public Utilities (many exceptions)
______(hereinafter referred to as “The Bidder”) does hereby acknowledges the understanding that this tender falls under the Domestic Trade Agreements. As part of these agreements and under the Nova Scotia Public Procurement Act, CBRM is included as part of the MASH Sector. This document forms part of and is incorporated into the Tender.
______Witness Bidder
Cape Breton Regional Municipality COVID-19 Protocol for Contractors and Suppliers
Date: April 20, 2020 Any contractor or supplier hired by Cape Breton Regional Municipality (CBRM) must adhere to the following protocols while working within and CBRM owned facility, or any CBRM owned property:
• Contractors and Suppliers must have their own COVID-19 Pandemic Plans prior to starting any work for CBRM. It must be available upon request. • Contractors or suppliers must seek approval prior to visiting and CBRM owned facility or property. Approval will be granted by the Manager/Director responsible for the specific site. • Contractors and suppliers shall only carry out work in approved areas during approved times. Any changes to work scope, schedule or location of work must be pre-approved by CBRM. • Anyone who has travelled outside of Canada or Atlantic Canada cannot carry out work at a CBRM facility or property until they have completed 14 days of self-isolation, measured from the date of their return to the Province. Any exemptions will have to be granted by Public Health. • When carrying out work within a CBRM facility, the Supplier or Contractor may only utilize up to 5 individuals to carry out the work. Outdoor construction sites are exempt from this requirement. • Supplier and Contractors must practice physical distancing of 2 meters(6 feet). • Number of in person meetings should be limited. If required, they should be 5 people or fewer, while maintaining physical distancing protocol. Use of teleconference and videoconference for meetings is encouraged. • The Supplier or Contractor must supply all employees with necessary materials to carry out regular disinfections of tools, equipment, and work areas. Where work is being carried out in a facility or area or worksite that does not have a washroom, the contractor or Supplier must provide the necessary equipment to allow for regular handwashing. • Suppliers and Contractors shall follow all guidance/requirements as issued by the Nova Scotia Medical Officer of Health and Public Health. • All Contractors and Suppliers must, to the best of their ability, closely self-monitor their health, and if their status changes then they must follow Public Health protocols. (e.g. contact 811) • Should any contractor or supplier exhibit any symptoms of COVID-19 during the period they are providing services to CBRM, or within the 2 weeks following, they must advise CBRM immediately.
Company Name:
Date:
Work Location:
Name(s) of Employee(s):
2020 novel coronavirus (COVID-19) self-assessment
1. Are feeling unwell with any of the following symptoms:
• Fever, new cough or difficulty breathing (or a combination of these symptoms)?
• Muscle aches, fatigue, headache, sore throat, runny nose or diarrhea?
2. And have experienced any of the following:
• Have you travelled outside of Canada or Nova Scotia in the last 14 days?
• Have you been in close contact (within 2 meters) with someone with a confirmed case of COVID-19?
• Have you been in close contact (within 2 metres) with someone who has returned from another country in the past 14 days and who has a fever higher than 38°C, a new cough or a cough that’s getting worse?
If you answered Yes to any of the following, contact 811. CBRM will have to restrict you from entering our buildings to provide service at this time. If you answered no to all questions above, CBRM requests you to practice the following on our sites:
• Wash your hand with soap and water or hand sanitizer upon entry to our facilities • Practice social distancing (2m or 6 feet) • Practice good hygiene practices (coughing into sleeves, etc) September 2020 Proposal No. P18-2020
______
REQUEST FOR PROPOSALS P18-2020
Prime Brook Floodplain Delineation & Watercourse Crossing Condition Assessments
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Cape Breton Regional September 2020 Municipality Request for Proposals # P18-2020
1. Project Background
In 2017 the Cape Breton Regional Municipality retained the services of WSP to conduct flood risk assessments within five major watersheds across the municipality. This work was completed by using the National Disaster Mitigation Program (NDMP) framework, specifically Stream (1) One – Risk Assessment. Part of the NDMP focuses on specific targeted investments, including developing specific tools, research activities, and public awareness activities. The NDMP is intended to address rising flood risks and costs, and to inform future mitigation investments that could reduce, or even negate, the effects of flood events.
In partnership with the Province of Nova Scotia under the Flood Risk Infrastructure Investment Program (FRIIP), the Municipality is now in a position to build on the results of the 2017 study by completing ‘Stream (2) Two” – Flood Mapping in the Prime Brook Watershed. This work will strengthen CBRMs ability to prepare for, respond to, and recover from, flood-related events by building a body of knowledge of flood risks in the region through foundational flood mitigation activities, such as flood mapping. This assignment will also include a comprehensive inventory and condition assessment of watercourse crossings such as culverts.
The aforementioned flood risk assessment completed by WSP included a prioritization process of the five watersheds with respect to the level of flood risks. The results identified two watershed systems with an overall priority level one (1), Renwick Brook in Glace Bay and Prime Brook in Sydney. Although both systems have the same priority level, they are very different in terms of size and complexity. For this reason, in conjunction with the available budget at this time, the Prime Brook watershed will be the focus of this assignment.
2. Goal
The successful proponent will be required to, among other duties, complete flood mapping of the Prime Brook Watershed and a culvert inventory and condition assessment from Highway 125 down to and including the two Kings Road Crossings. This work will be informed by the 2017 Risk Assessment. As described in the NDMP guidelines Stream 2 – Flood Mapping: “A flood map identifies the geographical boundaries of a flooding event based on the type and likelihood (i.e. 1:20, 1:50, 1:100 year) and this information is used to help identify the structures, people and assets that are within the flood zone that are most likely to be impacted by the defined flood event. Flood mapping information and data that is acquired from a flood mapping activity should then be used to update an area’s existing risk assessment(s). With this information, a community can more accurately determine its vulnerability(ies) in relation to a flooding event, and the flooding risk to the community”.
This work will help CBRM quantify the impacts from flooding of the identified system in an effort to reduce flood risks in the communities surrounding the Brook.
3. Objectives/Critical Path
The following milestones will be critical to achieving the objectives of this project: - Review of available background information; - Perform a comprehensive field program; - Report preliminary findings to CBRM; - Conduct detailed risk assessment of the identified areas with a prioritized list for future work; - Prepare flood mapping for 1:20, 1:50 and 1:100 year storm events and develop a prioritized capital upgrade / replacement plan for existing water crossings including class C (±30%) cost estimates.
4. Project Framework
In order to achieve the desired project outcomes, the Municipality will provide the following resources to the successful proponent: 20 | P a g e
Cape Breton Regional September 2020 Municipality Request for Proposals # P18-2020
- A copy of the WSP report; - A copy of the Municipal Climate Change Action Plan; - Access to most current local LIDAR data;
It is expected that the successful proponent will utilize these resources, along with information collected by the proponent during site investigations in order to complete the necessary analyses.
5. Detailed Scope of Consulting Services
The Municipality requires consulting services along the following themes:
- Civil Engineering - Hydrologic and Hydraulic Stormwater Analysis - Hazard Identification and Risk Analysis
The Proponent will be required to undertake, but not limited to, the following tasks:
- Review of available background information, - Liaise with Municipal Staff throughout the project and provide supporting documentation to Staff, - Prime Brook Watershed modelling analysis, - Refine existing and future flood limits, - Floodplain delineation for 1:20, 1:50, 1:100 and current peak events, - EMO procedures analysis i.e. evaluate emergency routes, evacuation plans, response measures, all based on study results, - Critical infrastructure field review and data collection, • photos • bed material • geometry (size and length) • survey invert elevations • roadway cross-section • channel cross-sections • LiDAR ground-truthing - Flow monitoring, - Rainfall monitoring, - Topo survey of channel cross sections and watercourse crossings, - Update the “Risk Assessment Information Template (RAIT)” (Appendix B) for Prime Brook, Watershed, - Assessment and inventory of major culvert crossings, - Physical condition assessments, i.e. function, structure etc. to identify culverts at risk of failure, - Identify risks of continued deterioration, which could result in failures during extreme events, - Investigation and assessment of underground infrastructure that may be located under existing homes / structures, - Investigation and assessment of highly erodible or historically eroded channel/ditch systems, - Coordinate and collaborate with NSTIR, Membertou, etc. where required, - Prioritization of asset upgrades / replacements as part of a capital culvert upgrade program including cost estimates.
6. Project Management
a. The proponent shall designate in their proposal, a project manager. All coordination for services with the Municipality and the consultant shall be the responsibility of the project manager. The project manager shall ensure that any substitutions in proponent team personnel are approved by the Municipality. 21 | P a g e
Cape Breton Regional September 2020 Municipality Request for Proposals # P18-2020
b. Report to the Municipality through meetings at various stages of the work program. The work progress shall be measured against a defined budget and work schedule. c. The Municipality recognizes that project management is an essential part of this project, therefore a written monthly progress report is required to be submitted and consist of the actual schedule achieved overlaid on the original base schedule submitted by the proponent at the start up meeting. For instances where the schedule has not been achieved a brief written explanation as to why shall be included. The progress report can be submitted either as a hard copy or as an attachment to an electronic e-mail. d. Meet; liaise with regulatory bodies, utilities, stakeholder groups, other levels of government, and members of the community, as required. e. Provide copies to the Municipality of all correspondence related to the project including agreements reached on behalf of the Municipality.
7. Reporting and Deliverables
a. Reports, drawings, and calculations shall be in metric units. Reports and drawings shall be stamped by a Professional Engineer registered to practice in Nova Scotia. b. Electronic copies of all information (reports, drawings, and calculations; e.g., spreadsheets, computer model data files, etc.) shall be provided to the Municipality on a USB flash drive. All reports are to be provided electronically, each as a single PDF file that includes the report text and all figures, diagrams, and drawings presented. In addition, drawings shall be provided in AutoCAD Current Version format and reports shall be provided in Word format. c. The proponent shall provide a label for the project flash drives with the following information:
Headline: Project Drive Title: Prime Brook Floodplain Delineation & Watercourse Crossing Condition assessments RFP Ref: 18.2020 Date: 2020/Month/Day Proponent: Consultant A
d. All material produced and information collected by the proponent in performance of this terms of reference shall become the property of the Municipality. All material shall be kept confidential by the Proponent unless authorized in writing by the Municipality. e. Where included in the scope of work, cost estimates are required and are to exclude HST.
8. Proposal Format and Requirements
• General Evaluation of proposals is simplified when proponents respond in a similar manner. The following format including section numbering, must be followed to provide this consistency.
• Format Proposals responding to this RFP should be prepared using a font no smaller than 10 point, on 8 ½"X 11"letter size paper, printed double sided.
• Title page Show Request for Proposal number and title, proponents name and address, closing date and time, proponent’s telephone number and contact person.
• Table of Contents Include a table of contents indicating the section and page of numbers of the information included.
• Executive Summary Responses shall include an abstract of no more than one (1) page on the information presented in the proposal 22 | P a g e
Cape Breton Regional September 2020 Municipality Request for Proposals # P18-2020
and the Consultant’s unique qualifications and services.
• Evaluation Criteria
A. Methodology – Approach
A-1 Scope of Work Statement The Consultant shall demonstrate a clear understanding of the project scope, objectives, and deliverables as well as identify any constraints or limitations that may impact the project delivery and its success.
A-2 Work Plan The Consultant shall identify the processes by which the team plans to meet the objectives including how the project will be organized, executed, managed and controlled. A clear project management approach must be demonstrated in order to deliver a successful project that will meet or exceed the project objectives.
A-3 Delivery Schedule The Consultant should provide a work schedule, in the form of a Gantt chart, including expected duration and completion dates for each task/phase.
For documentation requiring review by the Owner, please allow two weeks from the time the information is provided to the Owner until a reply is received.
For the purpose of the work schedule, Consultants may assume a project start date of October 5th, 2020 and that the project must be substantially completed before the end of March 2021.
A-4 Innovation and Creativity The Municipality will be looking for state of the art, innovative concepts that will provide cost effective community acceptable solutions.
B. Experience – Qualifications
B-1 Corporate Background Provide general information on the Consultant firm, no more than one (1) page, including a brief history of the firm and the number of years in business, capability to perform the work and local knowledge.
B-2 Relevant experience
Project experience should include a list of relevant (municipal) flood risk assessment projects and strategic studies. The projects must have been undertaken preferably in the past five years but no longer than ten years, supported with information on; successful completion of requested deliverables and the client.
Provide information on challenges in scope, cost and timeline management and how they were handled using the reference projects as examples.
Reference projects shall be presented with a limit of one (1) page per project.
B-3 References The Consultant should include references and also indicate if permission has been granted for CBRM to contact the client for each project reference.
The Consultant should include key team member’s history with the client over the past three to five years.
B-4 Proposed key team members and Resumes For key team members, include resumes and reference the role they played in similar projects. Limit of (1) page per key members.
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Cape Breton Regional September 2020 Municipality Request for Proposals # P18-2020
Upon award of the work, substitution of key members will not be permitted without approval of the Owner.
C. Cost of Service
C-1 Cost of Service Points to be awarded based on the Total Cost of Service for all items described in Section 6 “Detailed scope of Consulting Services” and is to be provided in the separate Sealed Cost of Services envelope.
All financial information regarding professional fees including hours used to calculate fees, travel time and expenses are to be provided in a seperate PDF and titled Cost of Services. Requests for optional fees such as optional site visits shall be presented on a separate sheet attached to the enclosed schedules.
The Consultant shall describe how Professional fees will be calculated, based on level of effort, for each of the tasks outlined Section 6. This detailed summary should include any services not itemized, but deemed necessary by the consultant.
9. Evaluation Criteria
Proposals will be evaluated using a two-step, two PDF procurement bidding procedure whereby the Technical and Cost of Services proposals will be submitted in two separate sealed PDF's marked accordingly. Proponents will be evaluated on the Technical proposal prior to the opening and evaluation of the Cost of Services proposal.
Evaluation Criteria Sub Score
Technical Evaluation A Methodology - Approach (Max 40 Points) A-1 Scope of Work Statement 8 A-2 Work Plan 16 A-3 Delivery Schedule 6 A-4 Innovation & Creativity 10
B Experience - Qualifications (Max 50 Points) B-1 Corporate Background 10 B-2 Relevant experience in presented reference projects 22 B-3 References 6 B-4 Proposed key team members and resumes 12
Sub-Total Technical Evaluation 90
Financial Evaluation C Cost of Service (Provided in a Separate PDF) C-1 Cost of Service (Max 10 Points) 10
Total (Technical + Financial) 100
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Weight Factor Table
The technical evaluation committee will use the following criteria and weight factors to evaluate the proposals submissions:
Weight Factor Excellent; meets and exceeds all of our requirements 100% 1 Very good; meets all of our requirements 90% 0.9 A sound response; fully meets most of our requirements 80% 0.8 Acceptable; exceeds our basic requirements 70% 0.7 Acceptable at a minimum level; meets our basic requirements 60% 0.6 Barely meets basic requirements 50% 0.5 Falls short of meeting basic requirements 40% 0.4 Exceedingly short of basic requirements 30% 0.3 Does not address our needs 20% 0.2 Information provided but unacceptable 10% 0.1 The response is completely unacceptable or the information is missing 0% 0 altogether
Technical Evaluation
A minimum of 54 points (60%) is required in the technical evaluation score in order to be considered further.
Cost of Service Evaluation
The proponents whose proposals meet the required technical evaluation score will be given a value relative to the lowest cost of service. The lowest cost of service will be assigned the maximum value of 10 points.
The cost Formula for the Evaluation is:
퐿표푤푒푠푡 푝푟표푝표푠푎푙 퐶표푠푡 푃표푖푛푡푠 푎푤푎푟푑푒푑 = 푥 푇표푡푎푙 푝표푖푛푡푠 푎푣푎푖푙푎푏푙푒 푓표푟 푐표푠푡 (10) 푃푟표푝표푠푎푙 푐표푠푡 푏푒푖푛푔 푒푣푎푙푢푎푡푒푑
All prices quoted in the proposal are to be in Canadian funds and are to show all applicable taxes.
Combined Score of Technical and Cost of Service
The preferred proponent will be selected on the basis of the highest overall score achieved by totaling the Technical and Financial scores.
The owner is not bound to accept the lowest cost of service or any proposal.
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10. Contact Information
Matthew D. Viva, P.Eng. Manager, Wastewater Operations (902) 563-5268 [email protected]
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APPENDIX A WSP Final Report
27 | P a g e CAPE BRETON REGIONAL MUNICIPALITY
NATIONAL DISASTER MITIGATION PROGRAM (NDMP) FLOOD RISK ASSESSMENTS
FINAL REPORT JUNE 21, 2019
October 12, 2016 CBC/Island Aerial Media NATIONAL DISASTER MITIGATION PROGRAM (NDMP) FLOOD RISK ASSESSMENTS
CAPE BRETON REGIONAL MUNICIPALITY
FINAL REPORT
PROJECT NO.: 181-03080 DATE: JUNE 21, 2019
WSP 1 SPECTACLE LAKE DRIVE DARTMOUTH, NS, CANADA B3B 1X7
T: +1 902-835-9955 F: +1 902-835-1645 WSP.COM June 21, 2019
Matt Viva, P.Eng. Cape Breton Regional Municipality Suite 104, 1st Floor 320 Esplanade Sydney, NS B1P 7B9
Subject: National Disaster Mitigation Program (NDMP) Flood Risk Assessments Final Report Submission
Dear Mr. Viva,
We are pleased to provide to CBRM the Final Report for the CBRM National Disaster Mitigation Program (NDMP) Flood Risk Assessments project. This submission includes the results of our Risk Assessment and Mitigation Planning process. This report was originally issued as a Draft in March 2019 and considered relevant to the information available during the completion of the project in 2018 and early 2019. Please note the subsequent June 2019 Amendment related to Climate Observations, outlined in Section 3.5 and Appendix C of this Final Report.
Yours sincerely,
Patrick Lewis, P.Eng. Manager – Infrastructure,
cc: Suzanna Lewis, P.Eng. – Assistant Project Manager (WSP) ClimAction Services Inc.
WSP ref.: 181-03080
1 Spectacle Lake Drive Dartmouth, NS, Canada B3B 1X7
T: +1 902-835-9955 F: +1 902-835-1645 wsp.com CONTRIBUTORS
CLIENT
CBRM Project Manager Matt Viva, P.Eng.
CBRM Staff
WSP
Project Manager Patrick Lewis, P.Eng.
Assistant Project Manager Suzanna Lewis, P.Eng., PMP
Engineer in Training Devin Bell
SUBCONSULTANTS
Senior Meteorologist Jim Abraham
Climate Change Meteorologist Gary Lines
Climate Change Strategic Planning Advisor David Kelly
Administrator Vikki Bewsher
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CBRM NDMP Flood Risk Assessments Page ii TABLE OF 1 INTRODUCTION ...... 6 1.1 OVERVIEW ...... 6 CONTENTS 1.2 NATIONAL DISASTER MITIGATION PROGRAM (NDMP) ...... 6 1.3 PROJECT SCOPE OF WORK ...... 7 1.4 GUIDING PRINCIPLES OF THE PROJECT ...... 8
2 BACKGROUND ...... 9 2.1 OVERVIEW OF FLOODING ...... 9 2.1.1 TYPES & CAUSES OF FLOODING ...... 9 2.1.2 IMPACTS OF FLOODING ...... 9 2.2 CLIMATE CHANGE AND FUTURE TRENDS ...... 10 2.3 RISK ASSESSMENT METHODOLOGY ...... 10 2.3.1 FUNDAMENTAL RISK ASSESSMENT PRINCIPLES ...... 10 2.3.2 NDMP RISK ASSESSMENT INFORMATION TEMPLATE (RAIT) .... 11 2.3.3 ONGOING MONITORING & REVIEW: ADAPTIVE MANAGEMENT 12
3 PRELIMINARY RISK ASSESSMENT ...... 13 3.1 PRELIMINARY RISK ASSESSMENT PROCESS ...... 13 3.2 MAPPING ANALYSIS ...... 13 3.3 SITE REVIEW AND CONSULTATION ...... 13 3.4 ANALYSIS OF HISTORICAL CLIMATE EVENTS ...... 14 3.5 CLIMATE TRENDS & PROJECTIONS ...... 15 3.5.1 HISTORICAL TRENDS ...... 15 3.5.2 FUTURE TRENDS ...... 16 3.5.3 SUMMARY OF CLIMATE ANALYSIS RECOMMENDATIONS...... 17 3.6 PRELIMINARY ASSESSMENT OUTCOMES ...... 17
4 RISK ASSESSMENT WORKSHOP ...... 18 4.1 OVERVIEW ...... 18 4.2 WORKSHOP FORMAT ...... 18 4.3 COLLABORATIVE RISK ASSESSMENT ...... 18
NATIONAL DISASTER MITIGATION PROGRAM (NDMP) WSP Project No. 181-03080 June 2019 CAPE BRETON REGIONAL MUNICIPALITY Page iii 5 DETAILED RISK ASSESSMENT ...... 20 5.1 OVERVIEW ...... 20 5.2 DEVELOPMENT OF RISK INVENTORY ...... 20 5.3 DETAILED RISK ASSESSMENT PROCESS ...... 20 5.3.1 IMPACT ASSESSMENT CRITERIA ...... 21 5.3.2 IMPACT ASSESSMENT RATING SCALE ...... 22 5.3.3 HAZARD MAPPING ...... 22 5.4 SUMMARY OF DETAILED ASSESSMENT RESULTS ...... 23 5.5 RISK ASSESSMENT OVERVIEW BY WATERSHED . 23 5.5.1 RESERVOIR BROOK ...... 24 5.5.2 PRIME BROOK ...... 26 5.5.3 RENWICK BROOK ...... 28 5.5.4 CADEGAN BROOK ...... 31 5.5.5 SMELT BROOK ...... 33 5.6 NDMP RISK ASSESSMENT TEMPLATE (RAIT) ...... 34 5.7 MITIGATION STRATEGIES & PRIORITIZATION WORKSHOP ...... 34 5.8 PRIORITIZATION...... 35
6 MITIGATION STRATEGIES ...... 36 6.1 DEVELOPMENT OF MITIGATION STRATEGIES ...... 36 6.1.1 COLLABORATIVE APPROACH ...... 36 6.1.2 NDMP FUNDING STREAMS ...... 36 6.1.3 ORDER-OF-MAGNITUDE COSTING ...... 36 6.2 MITIGATION STRATEGY OPTIONS ...... 37 6.2.1 FLOOD HAZARD MAPPING ...... 37 6.2.2 STRUCTURAL MEASURES ...... 39 6.2.3 NON-STRUCTURAL MEASURES ...... 40 6.2.4 FUNDING OPPORTUNITIES ...... 43
7 CONCLUSIONS ...... 44 7.1 PROJECT SUMMARY ...... 44 7.2 SUMMARY OF KEY IDENTIFIED FLOOD RISKS ...... 44
CBRM NDMP Flood Risk Assessments Page iv
7.3 SUMMARY OF KEY MITIGATION STRATEGY RECOMMENDATIONS ...... 46
BIBLIOGRAPHY ...... 47
TABLES TABLE 1.1 LIST OF 5 KEY WATERSHEDS ...... 6 TABLE 2: MAXIMUM RAINFALL AMOUNTS (MM) BY DURATION FOR 3 SIGNIFICANT EVENTS1 ...... 14 TABLE 3: PRECIPITATION AMOUNTS 1981- 2010 FOR SITES BASED ON CANGRID LOCATIONS ...... 15 TABLE 4: SYDNEY CS IDF RAINFALL (MM) BY DURATION AND RETURN PERIOD1 ...... 16 TABLE 5: CURRENT AND PROJECTED AVERAGE ANNUAL RAINFALL (MM) BY HORIZON FOR CANGRID SITES ...... 16 TABLE 6: CURRENT AND PROJECTED 24HR EXTREME RAINFALL (MM) BY RETURN PERIOD1 ...... 16 TABLE 5.1 PROJECT-SPECIFIC RISK ASSESSMENT SUB-CRITERIA ...... 21 TABLE 2: PRELIMINARY SITE PRIORITIZATION BY CUMULATIVE RISK...... 35 TABLE 3: SUMMARY OF FLOOD RISK BY WATERSHED ...... 45
FIGURES FIGURE 2.1: RISK METHODOLOGY ...... 11 FIGURE 5.1: OVERALL IMPACT CATEGORIZATION SCALE ...... 22
APPENDICES A FIGURES B RISK INVENTORY TABLE C CLIMATE OBSERVATIONS & PROJECTIONS D PHOTOGRAPHIC LOG (DIGITAL) E NDMP RAIT FORMS (DIGITAL)
CBRM NDMP Flood Risk Assessments Page v
1 INTRODUCTION
1.1 OVERVIEW
As part of the National Disaster Mitigation Program (NDMP), the Cape Breton Regional Municipality (CBRM) retained WSP to carry out flood risk assessments for 5 major watershed areas, focussing on the impacts at the community level. The NDMP was established by the Canadian Federal Government to focus on targeted investments to build safer and more resilient communities by addressing increased flood risks and the implementation of future mitigation measures. This NDMP fills a critical gap in the CBRM’s ability to effectively mitigate, prepare for, respond to, and recover from flood-related events, primarily by building a body of knowledge of existing flood risks in the region, and by investing in foundational flood mitigation planning and activities, such as risk assessments and flood mapping. The intent of the work is to investigate and define community-wide effects, impacts and risks associated with the flooding of these 5 major watershed areas to inform future decisions by CBRM. The results of the investigation will be used to support future funding strategies for the design and construction of flood mitigation infrastructure and measures within the Municipality. CBRM has identified five (5) watersheds of interest for Risk Assessment under the NDMP. The first stage of the NDMP is to investigate and document flood risks at these 5 areas, prioritize the sites for future work, and prepare a detailed risk assessment for these areas to inform future decision making. The five (5) key areas are indicated in the table below, and presented on Figure 1 the following page. Table 1.1 List of 5 Key Watersheds
AREA NO. WATERSHED SYSTEM DISTRICT
1 Reservoir Brook Sydney
2 Prime Brook Sydney
3 Renwick Brook Glace Bay
4 Cadegan Brook Dominion
5 Smelt Brook North Sydney
The current study falls under “Stream 1: Risk Assessment” of the Federal NDMP process, which involves identification of potential hazards and vulnerabilities, likelihood assessments, and review of impact(s) to people, economy, infrastructure, and the natural environment.
1.2 NATIONAL DISASTER MITIGATION PROGRAM (NDMP)
The National Disaster Mitigation Program (NDMP) was established in 2014 by the Canadian Federal Government. The program allocated $200M over five years to the NDMP, of which $183.8M is to be contributed to cost-shared projects with the provinces/territories, with remaining funding targeted to national-level initiatives. The primary objective is to reduce the impacts of natural disasters on Canadians by planning for future investments focussing on significant, recurring flood risks and costs; and advancing work to facilitate private residential insurance for overland flooding.
CBRM NDMP Flood Risk Assessments Page 6 The NDMP Guidelines issued by Public Safety Canada are available online1. The current study falls under the first of four available funding streams: • Stream 1: Risk Assessment (This Study) - Identification of the potential hazards, impact(s) of the hazard, community vulnerabilities, and assessment of the likelihood of occurrence. Involves determination of risk thresholds to serve as an informal decision-making support tool, and to inform the prioritization and selection of mitigation projects. • Stream 2: Flood Mapping - Flood mapping to identify structures, people and assets most likely to be impacted. • Stream 3: Mitigation Planning - Using information on identified flood risk to make informed planning decisions. Involves identifying broad mitigation goals, objectives/strategies, and key activities to meet the objectives. • Stream 4: Investments in Non-Structural and Small Scale Structural Mitigation - Implementation of a specific mitigation project. The NDMP recognizes that a comprehensive assessment of a flooding risk cannot be completed under Stream 1 alone. The intent of a Stream 1 project is to identify and assess flooding as a hazard risk using the best information that is available, understanding that flood mapping and/or modelling (i.e. Stream 2 activities) are required for the risk to be fully understood and assessed.
1.3 PROJECT SCOPE OF WORK
The first step of the Risk Assessment process involves compiling the necessary background information and conducting site visits to inform the preliminary assessments. The goal of the process is to develop a thorough understanding of the history and flood risk at each location, which is then used to prioritize the areas for future mitigation work. The risk assessments are conducted using the structure of the NDMP Risk Assessment Information Template (RAIT). Preliminary recommendations for proposed mitigation measures are then developed, complete with order-of-magnitude cost estimates for recommended remedial works. In summary, the approach to the NDMP Flood Risk Assessments involves the following activities: • Background Review & Information Compilation: — Review and compile all available background material on the 5 watersheds identified by CBRM. • Preliminary Risk Assessments & Site Prioritization: — Complete preliminary site investigations and preliminary risk assessments for the 5 watersheds. — Prepare a Preliminary Risk Assessment Report outlining a prioritized list for future works. • Stakeholder Workshop: — Facilitate a Risk Assessment and Mitigation Strategy Workshop with CBRM staff to inform the detailed risk assessments and mitigation strategies. • Detailed Risk Assessments: — Complete detailed risk assessments for the 5 watersheds, including RAIT form, site maps and photos. — Prepare a Final Detailed Risk Assessment Report. • Preliminary Mitigation Strategy Recommendations: — Develop Preliminary Mitigation Strategy Recommendations complete with order-of magnitude cost estimates for recommended remedial works.
1 https://www.publicsafety.gc.ca/cnt/mrgnc-mngmnt/dsstr-prvntn-mtgtn/ndmp/index-en.aspx CBRM NDMP Flood Risk Assessments Page 7 1.4 GUIDING PRINCIPLES OF THE PROJECT
The following guiding principles serve as a basis for all work performed as part of the current project: • Multidisciplinary Team Approach: The process was completed using a collaborative approach, involving an integrated team of consultants, subject matter experts, and CBRM departmental staff, including engineering, planning, emergency response, and operations personnel. • Founded on NDMP Assessment Criteria, with a Focus on Local Context: The project used a risk assessment and prioritization process based on the Federal NDMP program, while incorporating additional strategies to bring focus to the local context of the Cape Breton Regional Municipality. • Inclusiveness: A stakeholder workshop was conducted to gather background information and gather multiple perspectives, which helped to develop a collaborative understanding of the impacts of flooding at each site. • Consideration of Future Climate Change: The process examined future climate change factors by identifying the projected increase in the intensity and frequency of rainfall events, which could trigger flood events. This emphasizes the importance of planning, developing, and implementing flood mitigation strategies in the near future to protect against these severe weather events. Projections of future trends in precipitation patterns involved development of extreme climate scenarios in the next 50-100 years using the Climate Change Hazards Information Portal (CHIP). The supplementary report is titled “Climate Observations and Projections in Support of Flood Risk Assessment for Cape Breton Regional Municipality”, prepared by ClimAction Services Inc. • Evaluation of a Variety of Mitigation Options: The four (4) available NDMP funding streams were reviewed and considered as potential next steps for recommended mitigation strategies for each of the five watersheds. Additional possible funding opportunities were also identified. Mitigation strategies for the Municipality were developed in consultation with the key CBRM project stakeholders. Recommended next steps were identified with Rough Order of Magnitude Costing. Focus was placed on a risk assessment and mitigation strategy development considering a municipality-wide flood management approach for the region.
CBRM NDMP Flood Risk Assessments Page 8 2 BACKGROUND
2.1 OVERVIEW OF FLOODING
2.1.1 TYPES & CAUSES OF FLOODING
Flooding scenarios in CBRM are a result of specific meteorological events combined with the landscape condition, and may be more prone to occur during specific seasons. The overall climate of the region is influenced by its proximity to the Atlantic Ocean as well as its location on a storm track that includes intense Nor’easters as well as tropical cyclones. Flooding in CBRM can typically be described by the following mechanisms: • Flash Flood: High intensity, short duration rainfall can be related to intense meteorological events such as thunderstorms occurring as isolated summer event or embedded in large-scale storms. Such rainfall is usually intensified by dramatic slope in river valleys. • Heavy Rainfall: Most heavy rainfall (>50mm in 24 hours) is produced by intense Nor’easters or tropical cyclones. Both types of storms occur most frequently during the late summer, autumn and occasionally during the winter months. Associated with these winter events is rainfall often occurring on snow cover. This can create an enhanced flooding scenario by combining the rainfall runoff with snow melt runoff that subsequently would have minimal opportunity to infiltrate due to permeable surfaces being frozen. • Multi-day Accumulation: Rainfall that persists and accumulates over several days is typically related to slow-moving or stalled storms. Meteorologically these occur during a period where the west-to-east progression of storms is “blocked” by upper atmospheric features, prolonging their existence over the region. The ground slowly becomes fully saturated, limiting infiltration and resulting in a greater percentage of rainfall becoming direct runoff. Flooding from such storms can be intensified when persistent rainfall occurs during a thaw and creates run-off along frozen ground. • Coastal high water /storm surge: Coastal flooding can occur and worsen inland flooding when significant storm events combine with high tide, creating storm surge at the coast or mouth of rivers. These events can occur with intense Nor’easters, especially in the autumn. These scenarios have occurred in CBRM in the past and are projected to occur more frequently and intensely in the future with climate change.
2.1.2 IMPACTS OF FLOODING
Extreme flooding can have a variety of impacts on the affected community at both a small and large scale. The NDMP has defined various categories of impacts which are documented and evaluated using the NDMP Risk Assessment Information Template (RAIT). The NDMP RAIT was developed by Public Safety Canada for the input of risk information based on a completed risk assessment process, as described in more detail later in the report. Generally, the NDMP impact categories include: — People and Societal Impacts, which may result in significant societal disruptions such as human and other evacuations and relocations as well as injuries, immediate fatalities, and deaths from unattended injuries or displacement.
CBRM NDMP Flood Risk Assessments Page 9 — Environmental Impacts, which may include direct or indirect environmental damage resulting from a flooding event, and involving cleanup and restoration costs in the short-term and far into the future. — Local Economic Impacts, which may include the costs of damage and loss to local economically productive assets, as well as disruptions to the normal functioning of the local economic system of the community or the region for significant periods of time. — Local Infrastructure Impacts, which may include damage, disruption or destruction of the wide range of municipal and regional infrastructure systems such as transportation, water supply, wastewater management, and communications systems, the proper functioning of which the community depends on for its quality of life and viability. — Public Sensitivity Impacts, which include the operation and reputation of all levels of government, upon which the trust and welfare of the general public typically rests.
2.2 CLIMATE CHANGE AND FUTURE TRENDS
Since the 1950s there has been an increasing trend in extreme climate events across the globe. These events vary in type and frequency by region. For example, some regions receive more intense rainfall while others experience hotter days and extended drought. On a global scale, one of the more devastating events has been flooding due to heavy rainfall. Recent events in major urban areas of Canada include the Calgary, AB flood and recent inundation in Sydney, NS during Hurricane Matthew. In recognition of the importance of considering future climate change impacts on flooding, analysis of potential future precipitation events was performed as part of this project. Please refer to Appendix C for the full supplementary report, titled “Climate Observations and Projections in Support of Flood Risk Assessment for Cape Breton Regional Municipality”. The results of this report are further detailed in Section 3 of this report. Analysis indicates that as we progress through the next century, extreme events, especially heavy precipitation events, will continue to increase in frequency and intensity. The impacts on the built and natural environment in CBRM will become more severe, requiring various levels of adaptation measures to be developed and implemented. This consideration of the increasing flood risk in the future is a key guiding principle considered throughout the Risk Assessment process.
2.3 RISK ASSESSMENT METHODOLOGY
The current evaluation of impacts uses a risk assessment and prioritization process based on the Federal NDMP program, while incorporating additional strategies to bring focus to the local context of the Cape Breton Regional Municipality, as further described in this section.
2.3.1 FUNDAMENTAL RISK ASSESSMENT PRINCIPLES
Risk Management is the process of identifying risks, determining the likelihood of occurrence, severity of the consequences, and addressing those which are the most threatening to the community. A typical Risk Assessment Methodology process follows the following steps:
CBRM NDMP Flood Risk Assessments Page 10 Figure 2.1: Risk Methodology
Evaluate & Develop Monitor & Identify Assess Prioritize Response Review
1 Identify the Risk: What type of flood? What area is at risk? 2 Assess the Risk: What is the likelihood of the event occurring? 3 Evaluate and Prioritize Risks: Is the flood risk low or high? What are the most critical risks? 4 Develop Response: What mitigation strategies should be applied to manage the risk? 5 Monitor and Review: Continue to monitor risks and implemented mitigation measures. The current study begins the Risk Assessment process for five key watersheds in the CBRM. The study aims to identify, assess, evaluate and prioritize risks at the community level, identifying next steps for further risk analysis and development of mitigation strategies. The process incorporates key features of the federal NDMP as discussed in the following section.
2.3.2 NDMP RISK ASSESSMENT INFORMATION TEMPLATE (RAIT)
The NDMP RAIT was developed by Public Safety Canada for the input of risk information based on a completed risk assessment process. The program requires that the template be completed to proceed to the next stage(s) of funding (i.e. Streams 1-5). The NDMP Guidelines including the RAIT form, can be found online at https://www.publicsafety.gc.ca/cnt/mrgnc-mngmnt/dsstr-prvntn-mtgtn/ndmp/index-en.aspx. Completion of the RAIT generally involves the following activities: • Collection of Information for Identified Hazards Outlining and describing local risk, including an estimate of the likelihood of occurrence and examination of the potential magnitude and type of consequences or impacts related to the identified risk. The NDMP Guidelines suggest that risk event descriptions include historical context, as well as consideration of future risk from climate change. There are also considerations for existing infrastructure, technologies and community capabilities. • Assessment of Consequences and Impacts: Generally, the evaluation criteria within the RAIT are organized under five (5) specific impact categories, with the risks defined and ranked on a five-point scale. As discussed previously, the five impact rating categories include: — People and Societal Impacts — Environmental Impacts — Local Economic Impacts — Local Infrastructure Impacts — Public Sensitivity Impacts • Confidence Levels Completion of the RAIT also involves defining the level of confidence in the estimate and impact risk rating associated with the flood event. Confidence levels may vary depending on data availability, relevant expertise and information, and understanding of specific events. The levels are indicated by a rating raging from A to E where ‘A’ is the highest confidence level and ‘E’ is the lowest. The CBRM NDMP project involves completion of the RAIT for each of the five (5) key watersheds as a key component of the Risk Assessments process.
CBRM NDMP Flood Risk Assessments Page 11 2.3.3 ONGOING MONITORING & REVIEW: ADAPTIVE MANAGEMENT
It is important to note that the Risk Management process does not conclude at the completion of the current project. The mitigation measures and next steps identifies the work that will need to be implemented and planned for. Following implementation of proposed strategies, it is critical that CBRM continues to monitor the identified risks and take an adaptive management approach moving forward. This should include a review of the effectiveness of implemented measures into the future, including an evaluation based on future risk management processes, to identify new risks as the municipality grows, as the climate changes and as new regulations emerge.
CBRM NDMP Flood Risk Assessments Page 12 3 PRELIMINARY RISK ASSESSMENT
3.1 PRELIMINARY RISK ASSESSMENT PROCESS
The first stage of the NDMP Flood Risk Assessment process is as desktop review of available background information and field investigation of each of the 5 key watersheds to gain a better understanding of historical and potential flood risks within the community. Historical rainfall analysis, mapping, precipitation projections, and input from operations staff were used to inform the initial preliminary risk assessments for each of the 5 key watersheds. This section outlined the various components of the process. The results of the preliminary assessments were then carried forward to the stakeholder workshop and detailed risk assessments as part of the next stages of the project.
3.2 MAPPING ANALYSIS
In the early stages of the project, background information was compiled for the municipality and each of the 5 sites, including:
— Previously reported flooding issues, — Nearby public infrastructure systems, — LiDAR and Topographic mapping, — Publicly available site photos and aerial photos, — Previously completed background reports, — Anecdotal information, and — Municipal GIS data, — Previous media releases.
Through a desktop review, road and property mapping data were used to describe the characteristics of the watersheds and identify nearby areas and population groups that could potentially be impacted by surface flooding. Property mapping and knowledge of the communities has been used to describe the community and identify nearby areas potentially impacted by surface flooding, road-closures, public complaints, etc. Available topographic LiDAR data has been referenced to identity watershed boundaries, tributary areas and drainage paths, areas of low topographic relief or “trap-lows”, and downstream flow constraints. Another key tool in the risk assessment process was the use of available flood hazard mapping for the 5 identified watersheds to supplement and inform the assessments through identification of the relative risk within and between the watersheds. A Literature Review was also performed, aimed at acquiring information regarding flood management procedures and best management practices. This variety of background information has been paired with on-site field investigations and communication with Municipal staff to inform the Preliminary Risk Assessment process.
3.3 SITE REVIEW AND CONSULTATION
As part of the preliminary risk assessment process, WSP and CBRM staff performed a field review of the five watersheds on April 6, 2018. Patrick Lewis and Suzanna Lewis of WSP, and Matt Viva of CBRM met with various CBRM Operations personnel to review key risk areas and infrastructure within each watershed. The intention of the visits was to familiarize the project team with each site area, obtain site photos, and review drainage issues. The WSP team and CBRM project manager met with CBRM District Staff familiar with the infrastructure in each system. District staff led the group to the locations of key infrastructure
CBRM NDMP Flood Risk Assessments Page 13 within each system, and provided background information on past flooding, infrastructure condition and previous work. The presence of key operation staff was essential to help gain a historical context of each area and past flooding issues reported to CBRM. A photographic log of site visited within the CBRM can be found in Appendix D (digital).
3.4 ANALYSIS OF HISTORICAL CLIMATE EVENTS
A review of historical records and meteorological data was performed to identify when flooding events occurred, the intensity and duration of precipitation during the events, and impacts to the community. This section provides a summary of the meteorological review for CBRM. Please refer to Appendix C for the full supplementary report, titled “Climate Observations and Projections in Support of Flood Risk Assessment for Cape Breton Regional Municipality”. There have been several significant events in CBRM observed by the Environment Canada Sydney CS station during its period of record from 1961 to 2016. The most significant and recent event is the October 9th to 11th, 2016 rainfall event, known colloquially as the Thanksgiving Day storm. This was a long duration, lower intensity event which caused significant flooding and damage to infrastructure. However, there were also two short duration, high intensity events in this period of record which both produced greater rainfall depths than the Thanksgiving Day storm over the shorter 2- hour duration. The summary of these events can be found below. Table 2: Maximum Rainfall Amounts (mm) by Duration for 3 Significant Events1
Duration
YEAR 1hr 2hr 6hr 12hr 24hr 2016 25.3 49.1 101.2 189.3 224.1 1981 52.1 69.2 115.9 124.8 134.8 2012 48.8 66.2 NA NA NA
Note: 1Observations by Environment Canada Rainfall Station Sydney CS, ID 8205702
When compared to the Environment Canada IDF (Intensity-Duration-Frequency) Table for the region, all three events exceed expected 1:100yr return period amounts; either over the short duration period (1- 2hrs), long duration period (6-24hrs), or both.
1981 & 2012 EVENTS Based on review of the historical data, the 2012 event and the first half of the 1981 event would have had more significant impacts on urban infrastructure when compared to the initial portion of the 2016 event. The short duration, high intensity nature of rainfall during these periods would limit the effects of surface runoff attenuation for the lower portions of the overall watershed. These smaller areas are characterized by shorter times of concentration and more impermeable surfaces typical of an urbanized environment, as compared to the upper reaches of the overall watershed. The different runoff characteristics results in two peak flow events: the first being a sudden high peak flow from the lower, smaller urban reaches of the watershed, then a second from the majority of semi urban to rural watershed from the upper reaches. It is this nature of flow that generally results in significant localized infrastructure damage, but with less overall flooding extent and widespread damage than the longer duration, but less intense, storm events.
OCTOBER 2016 EVENT The persistence of rainfall at high or record values across the entire duration of the October 2016 storm set it apart from the previous record-setting event in 1981. This longer period of rainfall, building in intensity allows considerably more of the watershed to contribute over a longer period of time. Peak flow
CBRM NDMP Flood Risk Assessments Page 14 events in the lower reaches (produced by the relatively smaller sub-catchments of the watershed), are drawn out long enough for the upper reach peak event (produced by the significantly larger but more rural sub-catchments), to catch up. This results in overlapping peak flows, potentially greater than either individually, and prolonged over a longer period of time. It is the flow nature of these types of storm events that generally result in the more significant and widespread flooding, similar to what was experienced in the Thanksgiving Day storm.
3.5 CLIMATE TRENDS & PROJECTIONS
In recognition of the importance of considering future climate change impacts on flooding, an analysis of historical and potential future precipitation events in CBRM was performed. Please refer to Appendix C for the full supplementary report, titled “Climate Observations and Projections in Support of Flood Risk Assessment for Cape Breton Regional Municipality”. Amendment – June 2019: Environment Canada issued an updated suite of IDF curves on February 27, 2019, based on data from 1961 to 2016. The updated IDF curve relevant to CBRM (Sydney CS) included the October 2016 rainfall event and changed the values for every period and intensity. Due to this change, the updated IDF is now the recommended rainfall information suite when analyzing historical extreme rainfall events. Readers are advised that the original report and information provided in this section was completed prior to the February 27, 2019 IDF update. Please refer to the June 2019 Addendum to “Climate Observations and Projections in Support of Flood Risk Assessment for Cape Breton Regional Municipality” for further information on the updates and relevance to the data presented throughout this section.
3.5.1 HISTORICAL TRENDS
The first step to assessing future climate projections requires recognizing a climate “baseline”, identifying extreme precipitation events that have led to flooding historically. To help develop a climate “baseline” for CBRM three CANGRID points were located within the five watersheds of interest. Since the “baseline” values are generally presented as averages across months, seasons and years, the CANGRID approach provides relevant values for these five watersheds. Below is a summary of the historical precipitation amounts for the three locations. Table 3: Precipitation Amounts 1981-2010 for Sites Based on CANGRID Locations
SYDNEY GLACE BAY NORTH SYDNEY
Spring (MAM) 353.1mm 359.7mm 350.9mm Summer (JJA) 288.3mm 287.2mm 288.9mm Fall (SON) 405.6mm 410.7mm 410.5mm Winter (DJF) 415.9mm 423.0mm 418.1mm
Annual 1459.2mm 1476.9mm 1464.5mm
3-day Max Accumulation 114.8mm 115.3mm 120.5mm
Specific precipitation events can occur as short duration/high intensity events leading to flash flooding, or prolonged heavy events that cause flooding through accumulation of water. Rainfall events are monitored by Environment Canada to produce localized Intensity, Duration and Frequency (IDF) curves. These curves present a frequency of extreme rainfall rates and amounts corresponding to a variety of time duration ranging from 5 minutes to 24 hours. Return periods are used as the measure of frequency of occurrence and are expressed in years, ranging from 2 to 100 years. Environment Canada provides IDF information on the Sydney CS (ID 8205702), located at the JA Douglas McCurdy Sydney Airport, as summarized in the following table: CBRM NDMP Flood Risk Assessments Page 15 Table 4: Sydney CS IDF Rainfall (mm) by Duration and Return Period1
5min 30min 1hr 2hr 6hr 12hr 24hr
1:2yr 5.3 13.7 18.8 26.6 44.8 56.2 67.6
1:5yr 6.8 18.5 26.3 35.9 57.4 69.8 82.5
1:10yr 7.8 21.7 31.2 42.0 65.7 78.8 92.3
1:25yr 9.1 25.8 37.5 49.8 76.3 90.2 104.8
1:50yr 10.1 28.8 42.1 55.6 84.1 98.7 114.0
1:100yr 11.0 31.8 46.7 61.3 91.8 107.1 123.2
Note: 1Sydney CS, ID 8205702, current data based on observations up to and including 2014
3.5.2 FUTURE TRENDS
Evaluation of how flooding scenarios will change over the next 50-100 years involved projecting future changes to the identified climate “baseline”. These future extreme climate scenarios were developed using the Climate Change Hazards Information Portal (CHIP) to assess threats, risks and vulnerabilities, and develop adaptation strategies. Research indicates that the atmosphere is currently experiencing greenhouse gas concentrations that follow a “Representative Concentration Pathway” (RCP), similar to one which results in a warming of 8.5 watts per sqm, referred to as RCP8.5. To generate projections for average rainfall over the CBRM, future changes as developed from a climate model output were applied to the region’s “baseline” values, using the CCHIP tool. The tool provides output over the next century in 3 horizons: the 2020s (2011-2040), the 2050s (2041-2070) and the 2080s (2071-2100), as shown in the following table. Table 5: Current and Projected Average Annual Rainfall (mm) by Horizon for CANGRID Sites
Current Avg. Annual Rain 2020 2050 2080
Sydney 1459.2 1491.3 1535.0 1578.8 Glace Bay 1476.9 1509.4 1553.7 1598.0 North Sydney 1464.5 1496.7 1540.6 1584.6
To generate projections for the 24hr extreme precipitation values, the IDF_CC tool was accessed, using the same RCP8.5 scenario. It is noted that the IDF_CC tool only allows for 2, 50-year duration time periods across the next 100 years (i.e. 2010-2060 and 2050-2100), as outlined in the following table: Table 6: Current and Projected 24hr Extreme Rainfall (mm) by Return Period1
Current Rainfall 2010-2060 2050-2100
1:2yr 67.6 75.7 89.7 1:5yr 82.5 97.0 114.1 1:10yr 92.3 108.8 130.5 1:25yr 104.8 129.0 149.6 1:50yr 114.0 145.7 161.1 1:100yr 123.2 162.8 171.8
Note: 1As reported by the IDF_CC tool for Sydney CS, ID 8205702
CBRM NDMP Flood Risk Assessments Page 16 The analysis indicates that as we progress through the 21st century, extreme events, especially heavy precipitation events, will continue to increase in frequency and intensity. The impacts on the built and natural environment will become more severe unless various levels of adaptation measures are developed and implemented. The results of the climate projections support the decision by CBRM to initiate the flood risk assessment process today, required to help develop strategies as we move into the future with a changing climate, changing population demographics and aging infrastructure.
3.5.3 SUMMARY OF CLIMATE ANALYSIS RECOMMENDATIONS
The following provides a summary of the recommendations provided in the supplementary report “Climate Observations and Projections in Support of Flood Risk Assessment for Cape Breton Regional Municipality”: • Current projections of both the average annual values and the extreme intensity and frequency values for CBRM should be treated as conservative. • Based on the forensic analysis of the October 2016 event and its comparison to the 1981 event (which would have been included in the 2014 IDF curve for Sydney), none of the above projections are capturing the true nature of an extreme event for Sydney in the future. Amendment – June 2019: Since the completion of the original study, Environment Canada issued an updated IDF curve for CBRM (Sydney CS), based on data from 1961 to 2016, including the October 2016 rainfall event. The new IDF curve (issued February 27, 2019) is now the recommended rainfall information suite when analyzing historical extreme rainfall events.
• The 24hr amount for the Oct 2016 event at Sydney (224.1) should be considered the minimum 24hr amount for any future planning in the natural and built environment. It is recommended that this amount be increased by 20% by 2100 to allow for increased precipitation due to climate change. • The hourly rate of precipitation (as illustrated by both the 1981 and 2016 event) should also be increased by the same 20% to reflect the potential for increased overland flooding as well as flash flooding in narrow watercourses.
3.6 PRELIMINARY ASSESSMENT OUTCOMES
The preliminary assessment of risks within the 5 watersheds in CBRM involved the collection of background information, review of mapping, and discussions with CBRM staff and subject matter experts to obtain early indication of the issues, priorities and challenges associated with each of the 5 sites. As part of this process, information for the NDMP Risk Assessment Information Template (RAIT) was compiled for CBRM on a preliminary level. The main purpose of the preliminary process was to gain a baseline understanding of risk within the region, and provide an initial overview of risk for further detailed assessment. Prior to progressing to detailed assessments, the preliminary review was presented and discussed with key project stakeholders at the Preliminary Risk Assessment Workshop, as outlined in the following section.
CBRM NDMP Flood Risk Assessments Page 17 4 RISK ASSESSMENT WORKSHOP
4.1 OVERVIEW
A Preliminary Risk Assessment Workshop was facilitated with CBRM and key stakeholders on June 25, 2018. The workshop was designed to liaise with representatives from various CBRM departments such as engineering, community and land use planning, operations, environmental control and emergency services, as well as external stakeholders NSTIR and Membertou First Nations. The Risk Assessment Workshop served two primary purposes: • Informing Key Stakeholders on the risk assessment process, impact and vulnerability considerations, and climate change impacts. • Collecting Stakeholder input on risks, community vulnerabilities and mitigation opportunities through collaborative engagement.
4.2 WORKSHOP FORMAT
The first half of the workshop involved a presentation to inform the attendees about the NDMP program and the project-specific approach to the risk assessment process. The presentation included a program overview, an outline of risk assessment process, and a summary of the background information collected to date on each watershed. The second half of the workshop was dedicated to a collaborative risk assessment exercise, engaging the workshop participants to provide feedback and background information based on their on-the-ground knowledge. The following stakeholders attended and participated in the Risk Assessment Workshop: • WSP • ClimAction Services • CBRM Public Works and Planning Departments • Emergency Management • Nova Scotia Department of Transportation and Infrastructure Renewal • Membertou First Nations
4.3 COLLABORATIVE RISK ASSESSMENT
The collaborative risk assessment task was dedicated to engaging with the workshop participants to collect information on the flood risk and past flood events, community vulnerabilities, planned works/mitigation projects, and current response measures. This involved sharing of information pertaining to each watershed, such as the location of critical areas of past flooding, key access and routes, vulnerable infrastructure and populations, and known risks. The exercise also involved discussion of potential mitigation solutions, as well as comparison of risk. During the risk assessment exercise, a facilitated review of each watershed on large printed maps was conducted. The maps were used as an information collection and brainstorming tool to provide geographic context of each watershed. During this task, the workshop participants pointed out key risk areas and vulnerabilities which were then labelled on
CBRM NDMP Flood Risk Assessments Page 18 the map. Notes corresponding to each risk area were populated with information such as: • Infrastructure condition information • Flooding instances, both recent and historical • Possible mitigation options and strategies • Maintenance and condition concerns • Future development and proposed rehabilitation projects The collaborative mapping helped generate a greater understanding of the issues within each watershed, and how these individual risks pertain to the overall system. A sample of the workshop maps is shown below. Following the workshop, information documented as part of the preliminary stakeholder consultation was compiled to help inform the detailed assessment of key risks and development of mitigation strategies as outlined in the following sections.
CBRM NDMP Flood Risk Assessments Page 19 5 DETAILED RISK ASSESSMENT
5.1 OVERVIEW
The results of the preliminary risk assessment process and stakeholder workshop were used to inform the detailed risk assessment process. This task involved the compilation of information from the variety of sources, comparing feedback, anecdotal information, records, imagery and using professional judgement to provide an inclusive assessment of overall risks within the 5 watersheds. The ultimate goal of the detailed risk assessment process is to draw focus to specific areas or categories of risk, and identifying priorities for the municipality to aid in the development of mitigation plans.
5.2 DEVELOPMENT OF RISK INVENTORY
Through the preliminary assessment process, it was identified that much of the knowledge related to infrastructure and community vulnerabilities is held by a variety of stakeholders, including CBRM District Staff. Staff have experience-based knowledge on the watershed and surroundings, with a deep understanding of the past or potential impacts of flood events at the community level. Through the stakeholder consultation process, it became apparent that documentation of this knowledge was a necessary component to assist the municipality in developing priorities and strategies to address flood risk moving into the future. The first step in the detailed risk assessment process therefore involved the compilation of collected information, into a readily accessible document. A Risk Inventory Table was developed to present site- specific information from site investigations, consultation, background documents, and the stakeholder workshop. The intent of the Risk Inventory Table is to serve a database to document and cross-reference collected information such as infrastructure condition, known risks, anecdotal information and past flood occurrences at various locations within each watershed. Mapping the identified locations of interest also served to develop an understating of overall themes within the municipality related to flood risk. For example: geographic regions, infrastructure condition, topographical characteristics, etc. This provides an overall picture of identified risk elements within each watershed. Please refer to the mapping and inventory tables in Appendices A and B. Both documents serve as references for CBRM moving forward, and can be updated or transitioned into GIS or another reporting system. Note: The current study focuses on the 5 main watershed areas identified by CBRM in the scope of work. In addition, the scope of the inventory and assessment is limited to the locations examined with the guidance of CBRM staff and review by the project team. It is recognized that there are many other instances of localized flooding outside of these areas, therefore the inventory is intended as a starting point, and should not be considered a complete, exhaustive list.
5.3 DETAILED RISK ASSESSMENT PROCESS
The detailed risk assessment strategy for this project considers criteria from the NDMP Risk Assessment Information Template (RAIT) and implements a methodology specific to the nature of the project and the municipality. The following sections outline the assessment criteria and rating scales applied in the risk assessment process.
CBRM NDMP Flood Risk Assessments Page 20 5.3.1 IMPACT ASSESSMENT CRITERIA
The Impacts/Consequences Assessment presented in the NDMP RAIT involves scoring each site under several criteria, falling under the following categories:
• People and Societal Impacts • Local Infrastructure Impacts • Environmental Impacts • Public Sensitivity Impacts • Local Economic Impacts
While the RAIT is a comprehensive tool at the national level, it is important to consider the limitations of using the NDMP scoring system alone when comparing sites at the municipal level: — The RAIT scoring scale is considered broad. Prioritization requires more specificity to allow differentiation between sites. — Given that all watersheds are within the same geographic area (CBRM) and have similar physical and environmental characteristics, more discreet scoring is required to observe variations between the sites. — Since many of the RAIT criteria require further analysis to quantify and assign a definitive impact rating, the level of uncertainty at this preliminary stage results in similar scores across the sites. To provide a more comprehensive risk assessment and allow for prioritization of risk areas within CBRM, refined project-specific criteria were incorporated into the assessment process. The following Sub-Criteria were considered: Table 5.1 Project-Specific Risk Assessment Sub-Criteria Legend Original NDMP RAIT Criteria Project Assessment Criteria
1 Fatalities 1.1 General – based on Hazard Risk 2 People and Injuries 2.1 General – based on Hazard Risk 3 Societal Displacement (population) 3.1 Residential Property Damage 4 Duration of Displacement 4.1 General – based on Hazard Risk 4.2 Public Property Damage 5 Environmental 5.1 Protected Habitat 5.2 Wetland 5.3 Potential for Contaminant Release 6 Local Economic 6.1 Commercial Property Damage 6.2 Access to Businesses 6.3 Impact to Shipping/Trucking Routes 7 Transportation 7.1 Public Transit Route 7.2 Emergency Services Route 7.3 Commuter/Major Artery 7.4 Evacuation Route 8 Energy and Utilities 8.1 Overhead Power Lines 8.2 Power Substation 9 Local Information/Communications Technology 9.1 Overhead Communications Lines / Cell Towers Infrastructure 9.2 Communications Centre 10 Health, Food, and Water 10.1 Municipal Potable Water Supply 10.2 Private Water Wells 10.3 Hospitals 10.4 Emergency Services Buildings/Muster Points 10.5 Operations & Maintenance Requirements 11 Safety and Security 11.1 Impact to Police / Security Facilities 12 Public Sensitivity 12.1 Public profile of the area 12.2 Political Attention 12.3 Cultural/Historical Asset Damage
CBRM NDMP Flood Risk Assessments Page 21 5.3.2 IMPACT ASSESSMENT RATING SCALE
The current assessment is the first step in the process for the municipality, with limited analytical information available on the probability of flooding in the absence of a regional floodplain model. While a typical risk assessment process considers both probability (likelihood) and consequence (severity of impact), the project-specific risk assessment process was completed using a hybrid “Impact Rating Scale”. The hybrid rating approach is based on the premise that the overall risk at a given site is related to the presence, or lack thereof, of at-risk subjects (i.e. people, infrastructure, businesses etc.) and the general severity of resulting consequences if the area were to flood. This simplified approach is aimed at guiding the municipality towards priority areas to direct focus on more detailed analytical assessments in the future, such as development of a detailed floodplain model. For the purposes of this study, the following “Level of Impact” scale was used to categorize overall risk: Figure 5.1: Overall Impact Rating Scale
The impact rating process was primarily qualitative in nature, focussed on assigning a “Level of Impact” rating under each of the criteria noted in Table 2. The scale ranged from 0-3, with 0 being no impact (or not applicable), and 3 being a high level of impact. For example, a particular site could be assigned a score of “3” due to high density of residential homes existing within the floodplain of an urban brook, or at the site of a visibly deteriorated bridge structure (i.e. significant likelihood of damage/impact). Another site may be given a score of “1” due to it being a known natural floodplain, with minimal impacts to society, infrastructure etc. The ratings for each site were assembled based on background information, preliminary site investigations, and information provided by CBRM, as well as through evaluation by the project team and subject matter experts. Note: This risk scoring method was project-specific for the purpose of prioritizing key risks in relation to one another, and therefore does not correspond with the 1-5 rating scale in the NDMP RAIT template.
5.3.3 HAZARD MAPPING
Thematic flood mapping of watersheds and communities is a tool commonly used in flood risk assessment, but can be a complex and costly endeavor. The NDMP separates Flood Risk Mapping into a subsequent Stream 2 of the funding program, to be pursued following the initial risk assessment process. While flood mapping was outside of the scope of the current assignment, comparisons were made to a previously developed probabilistic flood model for Canada. This high-level mapping was developed by Impact Forecasting (AON) to help the insurance industry manage exposure to flood risk. These maps indicate information on flood hazard category (pluvial hazard index) and the vulnerabilities (hazard vulnerability index to vehicles, people, structures, etc.). Through a partnership with ClimAction Services Inc., sample high-level thematic risk map images were accessed for the 5 key areas of CBRM, with the goal to gain a better understanding of the relative risk within and between the 5 sites.
CBRM NDMP Flood Risk Assessments Page 22 5.4 SUMMARY OF DETAILED ASSESSMENT RESULTS
Overall, the NDMP Stream 1 Risk Assessment process indicated that there are real risks and vulnerabilities along each of the watercourses examined, with the potential to impact the society, safety, economy, infrastructure and environment within CBRM. The five (5) watersheds in the current study each contain a major natural watercourse system traversing through urbanized residential and commercial areas. Each of the watercourses have reaches located within close proximity to key infrastructure, including residential dwellings, schools, hospitals, areas of cultural significance, municipal water/wastewater utilities, and key transportation routes. This public and private infrastructure could be at risk of impacts during a peak flood event. The damage and impacts witnessed during past flood events, such as Hurricane Matthew (2016), indicate the potential severity of community-wide impacts resulting from flooding in CBRM. For example, impacts include irrecoverable damage to residential, commercial or municipal buildings, culvert blockages from natural or man-made debris, and subsequent road washout due to high velocities and volumes of water. Each of the watercourse systems are influenced by natural drainage, peak runoff from impervious urbanized areas, and downstream tidal/storm surge conditions. This first phase of the risk assessment process (Stream 1) indicates that further investigation and study is recommended and required to more clearly define the potential limits and vulnerabilities of infrastructure along each of the major watercourses. For example, field review and consultation with operations staff highlighted that many of the municipality’s watercourse crossing structures are in deteriorated condition or are possibly undersized, and should therefore be assessed and further evaluated for risk. Given that many of the watercourse crossings are on key transportation routes, the risk of limited or impaired access for emergency services is a primary risk to consider moving forward. The high volumes and velocities of water that were observed in the recent storm events, such as Hurricane Matthew (2016) are also indicative of risk to both infrastructure and human safety. Given the projected increases in the frequency and duration of rainfall with the changing climate, it can be expected that the identified risks will increase into the future. Adaptive management and mitigation measures must be considered to address the growing risk to the community.
5.5 RISK ASSESSMENT OVERVIEW BY WATERSHED
The following sections provide an overview of highlighted risks within each watershed, based on site review and stakeholder consultation. Please refer to Appendix B for more detailed supplementary risk information by location, shown in the Risk Inventory Table. It is noted that the follow discussion is intended to highlight key observations and identified risks in each watershed, but should not be considered exhaustive.
CBRM NDMP Flood Risk Assessments Page 23 5.5.1 RESERVOIR BROOK
CITY RESERVOIR The upper reaches of the Reservoir Brook watershed are primarily undeveloped south-east of Highway 125. This area naturally drains to the Municipal Reservoir located just upstream of the Highway. The main outlet of the reservoir discharges over a control weir structure and outlet channel, followed by a series of culverts. It was identified that this reservoir is a potential opportunity to provide upstream retention for the watershed during heavy rainfall events. It is important to note that any future development within the currently undeveloped upper watershed could increase the volume of runoff to the system, unless it is mitigated appropriately. In addition, as a potable water source the reservoir is highly sensitive to environmental impacts and potential health risk issues resulting from overland runoff. It is imperative that the watershed remain protected in an effort to mitigate these risks.
CAPE BRETON REGIONAL HOSPITAL The Cape Breton Regional Hospital is located within the Reservoir Brook watershed, just northwest of the highway. The hospital was flagged as a critical location of vulnerability due to vulnerability of its population. While the elevation of the hospital itself appears to be outside of the natural floodplain, its access routes cross several drainage routes which could pose a risk to restricting access during extreme conditions.
MEMBERTOU FIRST NATION LANDS The main tributary of Reservoir Brook crosses Highway 125 through several large culvert structures, before traversing through Membertou First Nation lands. The Membertou lands have undergone significant development in recent years, including both residential and commercial land uses. Lands south of the highway and west of the reservoir are currently under development expansion. It will be important that planned future development projects include considerations for stormwater and flood risk management. In addition, its is important to consider options to minimize the impacts of urbanization on increasing runoff to the natural watercourse system.
ROTARY PARK Reservoir brook crosses Churchill Drive through several large culvert structures, draining to Rotary Park near Terry Way. Rotary Park is a large natural area that is primarily vegetated and contains the Greenlink Trail system. The green-space along the banks of the brook was identified as a location for potential attenuation of peak flows in the system during peak flow events, to help protect the more urban downstream reaches. The Rotary Park system currently contains a man-made dam that creates a retention area between the dam and Churchill Drive. Due to the visibly aged condition of the dam, the structure has been identified as a potential risk and should be evaluated further. A dam failure could result in a rapid and immediate release of a large volume of flow at a high velocity, accompanied by debris, which could have significant resulting impacts downstream. It is recommended that the potential to increase the storage capacity in the park be considered if and when the dam is identified for replacement. CBRM NDMP Flood Risk Assessments Page 24 RESIDENTIAL AREA The lower reaches of Reservoir brook form a deep gulley with steep side slopes as it exits Rotary Park. A short section of the brook traverses an urbanized residential area behind homes on Cromarty Street, Harrison Avenue, Bentinck Street and Queen Street. Approximately 10 homes border the brook gulley in this area. The steep stream gradient in this section would likely result in high flow velocities in a storm event, causing bank erosion and generation of debris, and posing a potential risk to citizens. Eroded material and debris could also result in blockages and secondary risks in the downstream Wentworth Park.
ARGYLE STREET CROSSING Reservoir Brook then transitions into a pond just upstream of Argyle Street, which outlets through a single opening under the roadway. This opening is considered small in comparison to the size of upstream structures and overall width of the system. The undersized opening presents a risk for potential blockage from debris, particularly considering the high velocity and potential erosion in the steep upstream channel. If the opening capacity is limited or blocked, attenuation of flow in the pond has potential to build up and possibly overtop the road. In such a situation, the roadway would act as a dam structure, risking failure and subsequent impacts to the downstream system. CBRM staff have reported past blockages and flooding of the crossing in a peak flow event. This structure has been identified as high risk, and should be assessed and evaluated for upgrade.
WENTWORTH PARK Downstream of Argyle street, Wentworth Park contains the Municipality’s Bandstand, situated directly overtop of the Brook. Infrastructure has been upgraded in this area to provide additional flow capacity around the structure. Given the low elevation of the infrastructure in relation to ordinary water level, the risk of flooding of the structures and adjacent park still remains at this location. Downstream of the Bandstand, another pond occupies either side of the CN rail, crossing the tracks through double concrete box culverts. It is recommended that the condition and risk of these structures be evaluated by CN. At Bentinck Street, the pond is controlled by a stepped outlet weir structure, dropping under the roadway through a concrete bridge structure to a second pond. The most downstream pond discharges via a concrete box culvert under Kings Road, and is directly influenced by the tidal range of the Harbour. It is probable that the lower reaches of Reservoir Brook including the entirety of Wentworth Park could be subject to full or partial inundation by the tides, particularly in a storm surge event. This risk, paired with peak runoff and possible debris generation from the upstream system could further exacerbate flooding.
CBRM NDMP Flood Risk Assessments Page 25 5.5.2 PRIME BROOK
UPPER WATERSHED The upper watershed of Prime Brook contains wetlands and undeveloped green spaces upstream of Highway 125. Greenspace upstream of the highway has been identified as a potential location for attenuation of runoff, helping to control discharge to the more urbanized lower sections of the system. It is noted that some of the upper sections of the watershed have been urbanized. Future development, such as Monertay, Riverview and Fatima Drive expansions have the potential to increase runoff to the system and stormwater management must be considered to help mitigate impacts to the downstream system. After crossing the Highway, Prime Brook traverses mainly vegetated areas, passing through culverts at Kenwood Drive and Weider Drive.
BROOK SPLIT Between Weidner Drive and Newlands Avenue, Prime Brook occupies a flat, vegetated area behind residential homes. Drainage concerns have been identified by CBRM staff in this area, which is known to consist of peat material with poor subsurface drainage. Several homes in this area are located at low elevations, with little separation from the brook and potential floodplain. From this low area, the brook splits into two directions, West and East, as outlined in the following sections. The action of the flow split during flood events and flow volume directed to each of the respective downstream branches is currently not well understood. It is noted that the split may be an opportunity to proportionally redirect flow in either direction, depending on the downstream capacity of the respective systems.
WEST BRANCH From the Prime Brook flow split, the western branch of the system follows a more direct route towards the harbour, through a generally vegetated corridor behind homes on Weidener drive. The most critical risk identified in this section is in the lower reaches. Here the brook exhibits a steep gradient, with related risk of high flow velocities resulting in erosion and debris generation. The section of the brook approaching Kings Road has visible signs of erosion near homes, which reportedly has caused undermining of backyard structures from past flood events. In comparison to the east branch of Prime Brook, this system has less urbanization along its banks and only has a single crossing – King’s Road. If the option to divert upstream flow to the western branch is to be considered, this would require infrastructure capacity upgrades, erosion protection, and risk mitigation measures along bordering properties. This option may be worth considering to help divert flow away from the more urbanized east branch of the system to mitigate flood risk during a major event. A cost-risk-benefit analysis may identify the comparative cost to upgrade the west branch to handle more flow capacity is more feasible than required upgrades along the east branch.
CBRM NDMP Flood Risk Assessments Page 26 WESTERN KINGS ROAD CROSSING (WEIDNER DRIVE) The south-west crossing of Prime Brook at Kings Road is located at the base of Weidner Drive near the bottom of the watercourse system. This structure has been identified as a potential risk as the opening size is small in comparison to the size of the upstream system, and is located just downstream of a known location of erosion and debris generation. In addition, the crossing is located on a key transportation route and utility corridor which could pose secondary impacts to the public in the event of a failure. This structure was subject to failure during a flood event in recent years, requiring a complex repair and water line replacement. Consideration of any opportunity for flow diversion to this branch of the system must consider capacity upgrades to this crossing and susceptibility to blockage.
EAST BRANCH After the flow split near Newlands Avenue, the lower east branch of Prime Brook traverses an urbanized residential area just South of Kenwood Dr. Cross culverts are located at each intersecting street, many of which are in poor condition. For example, the twin corrugated steel pipes at Buckingham Drive, pictured to the right, exhibit visual signs of deterioration. Much of this section of the brook crosses private property, including some of the system’s subsurface piped infrastructure. The condition of much of the subsurface infrastructure is not well understood. In many cases, the open channel portions of the brook pass in close proximity to homes with the potential for fast flowing water and debris generation. Due to the close proximity to homes, as well as potential for infrastructure failure and road overtopping, The east branch of Prime Brook has been identified as high risk. A culvert condition assessment and replacement program has been recommended for this section of the system, as further outlined in Section 6.2. It is important to note that sanitary sewer and storm system upgrades in the area have been earmarked by municipal staff. As witnessed at the recent Marlbourough Drive culvert replacement, conflicts with the existing sanitary gravity sewer must be considered in future culvert design.
EASTERN KINGS ROAD CROSSING (HARBOURVIEW DRIVE) The eastern crossing of Prime Brook at Kings Road is located near the base of Harbourview Drive, consisting of a concrete box culvert structure. The structure has a defined outlet, pictured right, however the inlet appears to pass through private property. Land ownership and potential risk should be further reviewed at the inlet of this crossing. Downstream of Kings Road the system drops in elevation towards the CN Rail crossing and subsequently the Harbour. The Harbourstone Enhanced Care Facility is located in this area, though appears to be situated away from the brook with a significant elevation relief towards the Harbour.
CBRM NDMP Flood Risk Assessments Page 27 5.5.3 RENWICK BROOK
UPPER WATERSHED Renwick Brook is situated in the community of Glace Bay. To the southwest, the upper reaches of the watershed are primarily undeveloped and traverse flat, vegetated land. The main reach of the brook crosses Dominion Street near its intersection with Route 255, through a concrete bridge structure. Pictured left, existing sanitary sewer infrastructure lies within the bank of the brook at this location and throughout the system. The close location of a sewer to the brook poses a risk of stormwater inflow into the sewer system, which can contribute to sewer capacity challenges and system backup, further exacerbating operational challenges during a flood event. In addition, possible sanitary discharge back into the brook poses environmental and public health risks. It is recommended that the municipality review the function and location of the sanitary system along the entirety of the channel and examine opportunities to waterproof and/or relocate the most at-risk sections of the system.
CAMERON BOWL Downstream of Dominion Street, Renwick Brook passes through the Cameron Bowl ballfield and park. Infrastructure at the park infrastructure was flooded during past flood events, requiring repair and upgrades to the ballfield and trail bridge. It is important to consider the storage capacity of a low-lying greenspace such as the Cameron Bowl and its function in the natural watershed system. It is recommended that the municipality take measures to increase public awareness of the intended and accepted function of the system and set the expectation that it may, in fact flood in the future. It is also recommended that the municipality consider the resiliency of the park infrastructure to withstand future flood conditions in the known floodplain. Without proper protection, damage to infrastructure in this area could result in debris buildup downstream.
PARK STREET CROSSING Downstream of the Cameron Bowl, Renwick Brook continues through a deep gulley towards Park Street. This crossing comprises a cast-in-place concrete box structure within a deep road embankment. Municipal staff identified that the structure had been blocked with debris from upstream infrastructure failure at the Cameron Bowl in a previous flood event. This structure was identified as a potential high risk, given the structure size in comparison to the high flow volume and velocities in Renwick Brook. In addition, blockage of this structure in a high flow event could result in a significant build-up of water behind the road embankment, which could pose a secondary risk of catastrophic failure. The presence of large trees within the steep road embankment and above the structure also pose a risk for blockage with the potential to fall into the brook
CBRM NDMP Flood Risk Assessments Page 28
during a flood event. It is recommended that CBRM conduct a structure and capacity evaluation of this structure. The box structure also contains a concrete ledge which functions as a walkway in low flow conditions, however is often at or near water level. The ledge also contains the trunk sanitary sewer system. Given its close proximity to the brook and isolated location, this pathway is considered a potential risk to public users. It is recommended that structure measures be installed in the interim to prevent pedestrians from entering the structure. Staff also identified that there may be future plans for an Active Transportation (AT) corridor to extend the Renwick Brook Trail system upstream of Park Street. It is recommended that the municipality consider the future AT corridor when planning for structure upgrades if required, and consider the potential for floodwater bypass through this secondary corridor if constructed.
RESERVE STREET COMMERCIAL AREA West of the main reach of Renwick Brook, a tributary stream originates in a flat undeveloped area and traverses through the Reserve Street Commercial Area. The low-lying area surrounding Reserve Street contains several large shopping destinations, the community police station and community fire station. This area has been prone to flooding in the past, limiting access and causing damage to key businesses and emergency services in the area. The commercial area is situated in a natural topographic low area, with minimal elevation relief to the downstream system. It can be challenging to mitigate flooding in low areas like this, given the lack of natural topographic relief to convey flood waters out of the area. It is recommended that the municipality work to improve any downstream capacity restrictions to ensure flood waters can escape the area as quickly as possible. Community outreach and engagement with emergency services and business owners will be a key strategy to mitigating risks in the flood event. It is recommended that at a minimum, a local floodplain study be conducted to delineate the potential flood boundaries in a variety of events. The municipality then may wish to develop policy for future development, perhaps in alternate locations or incorporating flood protection and resiliency measures. Options for future relocation of emergency services facilities may be the most effective option for the police and fire stations, depending on the results of the floodplain analysis. In addition, the municipality may wish to consider the storage potential of the wetland area located immediately upstream of the Reserve Street commercial area to attenuate upstream runoff and reduce flows through the area in a high rainfall event.
WESTERN TRIBUTARY Downstream of the Reserve Street commercial area, the western tributary traverses a residential area, with crossings at Hickman Street, Rosewood Avenue, Mechanic Street, Union Street, York Street, Lower McLean Street and Catherine Street. This tributary joins the main Renwick Brook system just downstream of Park Street. It is important to consider the influences of these structures as possible restrictions on the watercourse, that could result in backwater effects upstream as far as the Reserve Street Commercial Area. In particular, staff identified past issues of debris blockages at the Hickman Street culvert. In situations such as this, the municipality may wish to consider expanding the size of inlet grate structures, regular preventative maintenance, and emergency response at known locations of debris issues. Several of the other structures along this tributary pass alongside residential homes, some of which experiences flooding during past events. Some of the structures appear to be aged
CBRM NDMP Flood Risk Assessments Page 29 corrugated metal culverts, which could be a risk for failure. It is recommended that the municipality consider a culvert condition assessment and subsequent replacement program along this section of the brook. A channel maintenance program should also be considered.
LOWER TRIBUTARIES There are two main tributary systems that drain to Renwick Brook within the lower section of the watershed, to the east and the west. These tributaries were not flagged as priority issues during the site review with CBRM staff, and were therefore not investigated in great detail. Staff did note that there has been residential flooding along the west tributary between Chappel Drive and Alexander Street in the past, thought to be due to the tributary being piped underground through an undersize collection system. It recommended that a culvert condition assessment program for the community consider crossings in these areas as well as review of the piped underground system, given the proximity to residential areas.
PEDESTRIAN BRIDGE CROSSING The lower reach of Renwick Brook begins to widen following the Park Street crossing. The brook is a deep gulley, with most major infrastructure located beyond the banks of the river. The Renwick Brook Trail system is located immediately adjacent the brook and likely within the floodplain. The pedestrian bridge crossing on the trail near May Street may be situated in the floodplain and should be reviewed for flood resiliency if there is potential for it being inundated in a peak event.
OUTLET SPILLWAY The main channel of Renwick Brook discharges to the tidal influence of the Atlantic Ocean over a weir spillway system located just upstream of the Commercial Street Bridge. CBRM staff have reported that the spillway is not classified as a dam. While the weir infrastructure appears to be functioning adequately under current conditions, it is recommended that the municipality consider the influence of future sea level rise and storm surge on both the function of the river system and risk to this infrastructure. Backwater conditions caused by future tidal conditions could have effects extending further up the river system.
COMMERCIAL STREET BRIDGE The Commercial Street Bridge is located immediately downstream of the control weir structure, spanning the full width of Renwick Brook. This section of the system is under the influence of the tides of the Atlantic Ocean. The crossing is a deck truss bridge, with its supporting structure located underneath the roadway. Given the potential susceptibility of the bridge super structure to flood waters below, it is recommended that the Municipality review possible peak water levels in the channel during peak tides in conjunction with storm surge conditions. A structural condition assessment of this aging structure should also be performed. The future replacement configuration should raise the underside of the bridge superstructure. In general, the main reach of the Renwick Brook system from Commercial Street to Dominion Street should be considered a high-risk area for public safety in a peak flood event, given the potential high flows, velocities and depth of water. Is it recommended that he municipality engage the community to raise awareness of the potential risks.
CBRM NDMP Flood Risk Assessments Page 30 5.5.4 CADEGAN BROOK
Cadegan Brook passes through several communities including Dominion, Bridgeport, and Glace Bay. The system has several upper reaches which merge upstream of Trunk 28.
RESERVE STREET The north tributary reach originates upstream of Dominion Street. The crossings at Dominion Street and McLeod’s Road are not well defined and should be investigated for further review of condition and capacity. This section of the system drains to a low-lying floodplain area on either side Reserve Street. This existing wetland area serves as a natural retention system. There may be opportunities to obtain additional storage capacity out of the natural system through downstream control, however effects on existing infrastructure must be considered. The existing Reserve Street crossing has minimal clearance and could become inundated during a flood. Depending on available upstream storage capacity, this could result in overtopping of the roadway. The municipality should consider alternate emergency route planning under current conditions. Existing sanitary sewer infrastructure is located along Reserve Street near this location, including a sanitary pumping station. This system is known to be impacted by past flooding. It is recommended that the municipality review the effects of flooding on this system, considering its location in the floodplain, limited access during a flood event, environmental effects of discharge to the wetland environment, and potential for surface water inflow into the sewer system. There have also been past reports of flooding of the adjacent mine water treatment system along Neville Street. Impacts on operation, the environment should be considered in coordination with the operator.
NEVILLE STREET The Western upper reach of the system crosses Neville Street before joining the main reach of Cadegan Brook. Crossings at Neville Street are mainly corrugated streel pipes, several of which appear to be in deteriorated condition. Low-lying sections of the roadway exhibit signs of deterioration from poor drainage. Should Neville Street become inundated by flood waters or failure of a culvert system, emergency access routes to nearby residences are significantly altered which could pose a risk to this population. It is recommended that the Municipality consider condition assessment and replacement of the structures in this area.
PHALEN ROAD The eastern tributary of Cadegan Brook originates north of Phalen Road. There are a number of culvert crossings along Phalen Road, some of which are not well defined or in poor condition. Many residential dwellings are located in close proximity to the drainage system in this area, and could be at risk in a peak event depending on water levels and culvert conveyance capacity. Re-routed emergency access in the event of a failure could add to response times for this community. The sanitary sewer system is also a key consideration in this area.
CBRM NDMP Flood Risk Assessments Page 31 It is recommended that the municipality consider a culvert condition assessment and replacement program for this area, which could potentially be coordinated in conjunction with the Neville Street system.
TRAIL CROSSING The central branches of each of the three main tributaries of Cadegan Brook traverse primarily undeveloped vegetated land with the potential to generate debris. The three tributaries converge upstream of the previous CN Rail route, now repurposed into a trail system, to form the main branch of Cadegan Brook. This trail crossing flooded and failed in the October 2016 event, and was subsequently replaced with a large circular concrete culvert. While the new structure reduces the risk of structural failure in comparison to the previous configuration, the municipality should still verify its capacity under peak and future flow conditions.
KINGS ROAD/MAIN STREET CROSSING Downstream of the trail crossing, the brook traverses a deep vegetated gulley before passing through a wooden box structure at Kings Road. CBRM staff reported previous damage due to blockage during a flood event, when flood waters rose behind the structure and nearly reached the elevation of the road. Although the structure has since been repaired, it is still considered a high risk, given the small size of the opening in comparison to the upstream brook. The high elevation of the road embankment adds increased risk of catastrophic failure in the event of a blockage. Should the crossing become obstructed, there is potential for water to pond to significant depth, potentially resulting in road embankment failure at Kings Road. Kings Road is a key emergency services and transportation route in this area, which could have significant impacts to the community if inaccessible. The possibility of deep flood waters and risk of road failure also poses a risk to society and drivers attempting to cross during a blockage. It is recommended that the municipality plan for upgrade of the Kings Road crossing and develop an interim emergency management plan to manage and monitor risk at the crossing during a flood event.
BROOK OUTLET Downstream of the Kings Road crossing, the brook continues through a deep gulley, passing the Municipal sewage treatment facility and discharging into the Atlantic Ocean. The lower reaches of the system are subject to tidal influence as well as sedimentation from wave action at the outlet. A review of the potential impacts of future sea level and storm surge conditions on the upstream brook should be considered. While the treatment facility is located at a higher elevation, the Municipality has identified that the sewer crosses the brook in this area. This infrastructure should be reviewed to ensure adequate protection measures to prevent damage from high flow velocities as well as infiltration from the Brook.
CBRM NDMP Flood Risk Assessments Page 32 5.5.5 SMELT BROOK
POTTLE LAKE RESERVOIR Smelt Brook is located in community of North Sydney. The upper watershed drains to Pottle Lake, which functions as the potable water reservoir for the community. The outlet of the lake is controlled by an adjustable weir system, located just downstream of Highway 125. The lake and control system presents a potential opportunity to attenuate flow volumes during a peak event with controlled release to the downstream system. It is recommended that upgrades or modifications to the outlet structure be reviewed for the possibility to increase the storage potential of the lake in storm conditions. The system then passes through a concrete box structure under Musgrave lane, draining eastward. The downstream banks of the channel are bordered by vegetation, which could result in buildup of debris in the channel during a high flow event.
WILKE DRIVE CROSSING Where Smelt Brook crosses Wilke Drive there are four residential properties that border the channel, with minimal elevation difference from the normal water level. The Wilke Drive crossing structure is an aged concrete structure, however CBRM Operations staff have not reported past issues with the structure. It is recommended that the crossing be reviewed and evaluated for capacity and structural integrity, as risk of failure or backup could have detrimental affects on the adjacent residential properties, particularly given their proximity in elevation to the channel.
RAIL CORRIDOR CROSSING The system then crosses the abandoned CN Rail through an arch culvert. The rail and embankment at this location is significantly higher than the watercourse elevation. The structure could pose a potential risk due to its age, condition, and lack of future maintenance given the abandonment of the rail line. If the structure were to fail or become blocked, the rail embankment would function as a dam. Without a safe by-pass route, this could result in rising upstream flood waters and risk of catastrophic embankment failure, with associated impacts downstream. It is recommended that the municipality coordinate a structure review of the crossing and examine potential for a secondary bypass routing as a risk mitigation measure. The next downstream brook crossing at Regent Street was recently upgraded to a precast concrete arch structure. While the structure upgrade reduces the risk of failure, the adjacent properties in the area may still be at risk of flooding from the stream given their close proximity and limited elevation differential.
CBRM NDMP Flood Risk Assessments Page 33 PIERCE STREET CROSSING AND SMELT BROOK PARK The next downstream crossing at Pierce Street was also upgraded in recent years. This structure discharges into the low-lying Smelt Brook Park. It is understood that this section of the system is influenced by the downstream tidal range of the Harbour. Past flooding of Pierce street and the surrounding area has been reported. This area contains the North Sydney Fire Department and fueling station and the Fireman’s Club. It is understood that the club has been proposed as a warming facility for emergency situations. The fueling station presents both a risk to emergency services if fire trucks cannot access the fuel during a flood event, as well as an environmental and safety risk if the fuel tanks are flooded. The location of the emergency services infrastructure within a known floodplain is a significant risk in this watershed, and should be reviewed by the Municipality. Given the influence of the tide on the system, localize flood mitigation is challenging. its is recommended that the Municipality consider relocation of this critical infrastructure outside of the floodplain.
BROOK OUTLET TO THE HARBOUR Downstream of Smelt Brook Park, the watercourse crosses Queen Street thorough a small concrete bridge into a rectangular, man-made channel discharging to the Harbour. Considering the possible volume of upstream water during a peak flow event, it is recommended that this structure and channel be evaluated from a capacity and structural perspective for performance during a freshwater peak flow event, to confim if the flow can pass freely into the Harbour. It is important to note that under extreme tidal conditions, including storm surge and sea-level rise, the system is controlled by the downstream water levels. Channel capacity upgrades are therefore not likely to remediate the flooding conditions upstream. Much of the coastal infrastructure in this area, including the adjacent processing plant, commercial businesses and Queen Street, should be assessed from a coastal flood risk perspective. Since the lower reaches of the Smelt Brook watershed are tidally influenced, the primary recommendation is to address emergency planning and consider relocation or raising of existing infrastructure outside of the floodplain.
5.6 NDMP RISK ASSESSMENT TEMPLATE (RAIT)
In addition to the risk assessment work conducted for CBRM, the scope included completion of the Risk Assessment Information Template (RAIT) for potential submission for future funding opportunities. The completed RAIT for the Municipality is included in Appendix E (Digital).
5.7 MITIGATION STRATEGIES & PRIORITIZATION WORKSHOP
A second stakeholder workshop was facilitated with CBRM staff on February 11, 2019. This workshop was designed to liaise with representatives from various departments including engineering and operations. The Mitigation Planning Workshop served two primary purposes: • Informing and gaining consensus from key stakeholders on the results of the detailed risk assessments • Informing and gaining consensus from key stakeholders on recommended mitigation strategies and funding opportunities. CBRM NDMP Flood Risk Assessments Page 34 The workshop was dedicated to a collaborative discussion on watershed-specific mitigation strategies, engaging the workshop participants to provide feedback and background information based on their on- the-ground knowledge. The Mitigation Planning Workshop was attended by: • CBRM Public Works Engineering & Operations Staff • WSP • ClimAction Services
5.8 PRIORITIZATION
To gain an understanding of the comparative level of risk between the five watersheds, a prioritization process was performed by examining the cumulative risks at individual sites, as identified during this study and shown in the Risk Inventory Table in Appendix B. Risk indicators for the watersheds were developed by combining risk scores for individual sites and structures flagged during the risk assessment process. These indicators included a sum of risk scores, average of risk scores, and count of risk sites identified. The watersheds were ranked from 1-5 for each of the three indicators, and these rankings were then averaged to identify an overall priority ranking from highest to lowest priority. Table 9 summarizes the prioritization scores and ranking: Table 2: Preliminary Site Prioritization by Cumulative Risk Cumulative Average Risk No. Identified No. Priority Watershed Risk Score Score Risk Sites Identified District System Overall Average Un- Score Rank Score Rank No. Rank Priority Ranking knowns Renwick Glace 1 2 57 1 1.9 4 30 1 26 Brook Bay Prime Sydney 1 2 35 2 2.3 1 15 3 6 Brook Reservoir Sydney 3 3.3 32 3 1.5 5 21 2 23 Brook Cadegan Dominion 4 3.7 29 4 2.1 3 14 4 17 Brook Smelt North 5 4 25 5 2.1 2 12 5 2 Brook Sydney The prioritization ranking can be considered indicative of the overall comparative level of risk within each district, however it is noted that the ranking is heavily influenced by the watershed size. Generally, the larger the watershed, the higher number of watercourse crossings, and therefore a greater number of identified risk sites and higher cumulative risk. The following key points should also be considered: • Prioritization is Relative: The project-specific prioritization process scores and ranks the 5 key watersheds in relation to each other. • All 5 Watersheds are priorities for the Municipality: The prioritized list is not intended to be definitive. Ideally, mitigation measures would eventually be implemented for all locations. • Prioritization is a Tool to Direct Focus: Prioritization is a tool to help guide the planning and preparing for implementation of mitigation measures in a sequential and effective manner. By prioritizing the sites of highest risk, focus can be dedicated to developing site-specific strategies. This focus helps to achieve action that is manageable in applying for and receiving funding. • Limited by Scope of the Study: The prioritization scoring is highly influenced by the size of the watershed, and the availability of information at the time of the study. It is expected that following further investigation and assessment, risk priorities may change from those presented herein. It is also important to note that the project-specific prioritization scoring process is independent from the NDMP RAIT scoring system. The NDMP RAIT scoring is applied in accordance with the program requirements, specifically for the purposes of applying for federal funding.
CBRM NDMP Flood Risk Assessments Page 35 6 MITIGATION STRATEGIES
6.1 DEVELOPMENT OF MITIGATION STRATEGIES
Once flood risk and impacts were identified in the five watersheds across the Municipality, the next step involved review and recommendation of strategies and measures to help mitigate the risk and impacts. Mitigation strategies were reviewed for each of the five sites, as well as on a municipal-wide level. The following sections outline information and considerations used to develop potential strategies for the municipality.
6.1.1 COLLABORATIVE APPROACH
Initial mitigation strategy concepts were developed by the project team in the early stages of the project following site review and assessment of risk at the project sites. During the stakeholder workshop, attendees were asked to comment on the suitability of the potential mitigation strategies, suggest any additional strategy concepts, and comment on potential coordination of strategies with other planned or upcoming work. In recognition of common themes for addressing flooding in the five sites, opportunities for implementation of municipality-wide mitigation strategies were also identified. To help inform the development of potential mitigation strategies to address flooding challenges across CBRM, a literature review was also conducted to examine mitigation techniques, adaptation strategies and best management practices (BMPs) from other municipalities and jurisdictions.
6.1.2 NDMP FUNDING STREAMS
In recognition of funding opportunities through the Federal National Disaster Mitigation Program, potential mitigation strategies were categorized under the available subsequent funding streams: • Stream 2: Flood Mapping – Defining the geographical boundaries of a flooding event, used to help perform an updated risk assessment of flood impacts. • Stream 3: Mitigation Planning – Using risk information to make informed planning decisions. Involves identifying mitigation goals, strategies, objectives and key activities. • Stream 4: Investments in Non-Structural and Small Scale Structural Mitigation – Implementation of a specific mitigation project The NDMP Streams are further defined in Section 2 of this report.
6.1.3 ORDER-OF-MAGNITUDE COSTING
Rough Order of Magnitude costs have also been developed for the recommended strategies. The intent of the costing is to give CBRM an indication of the potential level of effort required for the identified works. It is important to note that estimates of this nature are considered high-level, and should be further reviewed against a more detailed project scope of work – once defined by the municipality – when allocating capital funds.
CBRM NDMP Flood Risk Assessments Page 36 6.2 MITIGATION STRATEGY OPTIONS
Following review of available mitigation strategies, key recommended next steps for the immediate future have been developed in consultation with CBRM. The recommendations have ben prepared recognizing both available municipal funding and the conditions for the subsequent NDMP funding streams. CBRM is encouraged to consider opportunities to expedite further assessment and implementation of the suggested next steps wherever possible.
6.2.1 FLOOD HAZARD MAPPING
1) Regional Watershed Flood Mapping Study
➢ Rough Order of Magnitude Cost: $150-200K (NDMP Stream 2- Floodplain Mapping)
Conduct a municipality-wide flood mapping exercise using available data and information to further identify flood risks and vulnerabilities. • Regional level study of the 5-6 major watersheds, to better understand existing and future flood limits. • High-level floodplain delineation for major flood events (such as 1:50, 1:100 year). Consider current and future climate change scenarios. Define existing and future flood limits. • Primary study goals: • Identify critical structures/areas of risk for further detailed study/mapping. • Further refine flood risk assessment based on study results. • Review and prioritization of non-structural and structural mitigation strategies. • The mapping task should identify, at a minimum: • Approximate flood extents under extreme events • Vulnerable communities • Critical infrastructure • Other Considerations: • Coordination with NSTIR, Membertou First Nation, and other Stakeholders. • Include Community Engagement to inform the public of study results/Identified Flood Risks. • Review Emergency Management Procedures based on the floodplain defined by the study. • Key inputs to the high-level mapping study should include: • LiDAR Mapping • GIS Data (including, piped infrastructure, houses, roads, critical infrastructure, etc.) • Aerial Images • Mapping of known watercourses • Approximate structure geometry, where available. • Tidal Data (Environment Canada) • Rainfall Data (Environment Canada) • Field review and data collection of critical structures along major watercourses is also recommended.
1a) Supplementary Data Collection Detailed Flood Mapping & Modelling
➢ Rough Order of Magnitude Cost: Additional $25-50K (NDMP Stream 2- Floodplain Mapping)
To supplement a high-level mapping study, conduct field review and data collection of critical structures along the major watercourse, including: photos, bed material, geometry (size and length), survey of invert elevations, roadway cross-section, channel cross-sections, and LiDAR ground-truthing. CBRM NDMP Flood Risk Assessments Page 37 2) Watershed-Specific Floodplain Delineation
➢ Rough Order of Magnitude Cost: $50-150K, per watershed (NDMP Stream 2- Floodplain Mapping) Alternatively, a Detailed Flood Mapping study could be performed for the municipality as a whole, or each of the 5 individual watersheds individually. It is noted that the level of effort and associated cost of the task varies by complexity of the watersheds. Conducted to a finer level of detailed than the high-level mapping exercise, this exercise includes data collection for various watershed-specific elements required to create a more detailed model for each watershed. This level of effort would allow for a more thorough understanding of the watershed and its response to a severe event, to aid in more detailed understanding the extent of flooding under a variety of conditions. A Detailed Flood Mapping study should include the following: • Hydrologic/hydraulic Analysis: • Watershed-specific modelling analysis for each of the 5 watersheds highlighted in this report. • Refine existing and future flood limits. • Floodplain Delineation: • For a variety of peak flood events including 1:20, 1:50, 1:100 year • Consider both current peak events and future climate change. • Include Community Engagement: • Inform the public of study results/Identified Flood Risks. • Review of Emergency Management Procedures: • Evaluate existing emergency routes, evacuation plans, and response measures based on the floodplain defined by the study. • Field Review & Data Collection: • At a minimum, conduct a site review and collect survey data for critical structures along the major watercourse. • Include photos, bed material, geometry (size and length), survey of invert elevations, and roadway cross-section, channel cross-sections, where possible, and LiDAR ground-truthing. • Additional information which could be collected for an increased level of detail, depending on scope and available funding: • Flow monitoring at storage outlets and critical watercourse reaches; • Rainfall monitoring; • Topographic survey of lake outlets, channel cross sections and watercourse crossings; • Bathymetric survey of storage facilities (i.e. lakes, ponds); • Information obtained in the Culvert Condition Assessment Program.
CBRM NDMP Flood Risk Assessments Page 38 6.2.2 STRUCTURAL MEASURES
1) Inventory & Condition Assessment of Watercourse Crossings
➢ Rough Order of Magnitude Cost: $25-150K, per watershed (NDMP Stream 2- Floodplain Mapping)
Conduct a comprehensive Inventory and Condition Assessment Program of watercourse crossing structures (culverts, bridges, etc.) to better document and understand the condition and vulnerabilities of critical infrastructure along each major watercourse. This exercise could be completed to supplement either of the above Flood Mapping exercises. It is noted that the level of effort and associated cost of the task varies by complexity of the watersheds. The task would involve the following: • Assessment and inventory of major culvert crossings within the Municipality, along each of the major watercourses. Information collected should include: • Condition (Including Photos) • Material • Geometry (Size and Length) • Survey of Invert Elevations, and Roadway Cross Section • Results of the program would inform prioritization of asset upgrades as part of a culvert replacement program. Data could benefit watershed flood mapping studies. • Other considerations include: • Physical condition assessment (function/structure/debris) to identify culverts at risk for failure due to poor structural integrity. Possible coordination with GIS/Asset Management Systems. • Identify risk of continued deterioration, which could potentially result in failures during extreme events. • Include investigation and assessment of piped infrastructure that may potentially be located under existing homes/structures. • Include investigation and assessment of highly erodible or historically eroded channel/ditch systems. • Coordination and collaboration with NSTIR, Membertou First Nation, and other Stakeholders.
2) Culvert Replacement Program
➢ Rough Order of Magnitude Cost: Approx. $70-250K depending on size (NDMP Stream 4 – Investment in Infrastructure),
Development of an annual Culvert Replacement Program based on the results and prioritization of the Condition Assessment Program as well as the Watershed Floodplain Mapping. • Consider adjacent infrastructure, including sewer systems. • Coordinate upgrades with the flood critical remediation projects and GIS/Asset Management Systems. • Consider packing multiple culvert replacements together for design and construction efficiencies. • Upstream replacements must consider potential interim downstream impacts or interim control measures to minimize downstream impacts prior to upsizing. It is noted that the level of effort and associated cost of the task varies by size and complexity of the crossing.
CBRM NDMP Flood Risk Assessments Page 39 3) Large Structure Replacement Projects
➢ Rough Order of Magnitude Cost: Approx. $200K-$1M+ each depending on size (NDMP Stream 4 – Investment in Infrastructure)
This task includes the condition assessment, detailed design and construction of upgrades to existing bridge crossings, and/or the design and construction of culvert upgrades to larger bridge structures if determined necessary by the results of a capacity analysis. • Plan to construct bridges and larger culverts as individual capital projects. • Prioritize based on results of condition assessment. • Consider at locations such as Park Street Crossing (Renwick Brook), Kings Road Crossing (Cadegan Brook), etc.
4) Flood Remediation Measures
➢ Rough Order of Magnitude Cost: Approx. $100K-$1M+ each depending on size (NDMP Stream 4 – Investment in Infrastructure)
It is important to note that construction of structural measures to protect against flooding is only considered a partial solution. Flood protection measures can unintentionally serve to encourage future encroachment into floodplains, thereby raising potential for future flood damage if the structural protection measures were to fail. Each of these options will require ongoing maintenance, which can tend to be ignored since large-scale events are rare. Possible structural flood remediation measures may include: • Surface retention w/ control structures2 • Flow diversions3 • Protection measures (e.g. berms)4 • Channel widening • Floodproofing measures for critical buildings/ infrastructure • Natural Flood Management measures in upper rural watershed portions The design of any flood mitigation measures will require hydraulic modeling, detailed design and construction phases.
6.2.3 NON-STRUCTURAL MEASURES
The primary long-term flood mitigation strategy involves keeping vulnerable development and land uses out of floodplains. The strategy of locating infrastructure and communities out of known flood zones has the following benefits: • Reduces the need for expensive flood control structures. • Reduces the demand for disaster assistance payments. • Widely accepted by other jurisdictions.
2 https://globalnews.ca/news/4350615/high-river-floodgate-construction/ 3 https://www.richmondhill.ca/en/our-services/Stormwater-Management.aspx 4 https://www.externalworksindex.co.uk/entry/135308/TenCate-Geosynthetics/Geotube-geotextile-systems-for-marine-structures/ CBRM NDMP Flood Risk Assessments Page 40 Coordination is a key component of any non-structural mitigation strategy for the municipality, including the following recommended concepts: • Incorporate flood risk/mitigation into all capital projects; • Coordination between coastal/pluvial flood studies; • Information sharing between agencies; • Inter-departmental/utility coordination; and • Dedication of a Flood Management Action Team. In development of the mitigation strategies for each watershed, common themes were identified for adaptation and mitigation that could be applied to sites beyond the limits of the current study. The following relevant flood mitigation techniques and adaptation strategies were reviewed for potential application in addressing flooding challenges across CBRM. These strategies come together to form a proposed Municipality-Wide Flood Management Strategy.
DATA COLLECTION AND MONITORING STRATEGIES
1. Data Collection and Monitoring
• Flow and water level monitoring as the collection of flood-related data will help improve understanding of flood risks within the municipality and inform future planning initiatives. • Logging of historic and ongoing flooding in a digital database to allow for forensic analysis, including information such as: — Location of surface flooding; — Nature of the area (intersection of roads, Road dip); — Depths and extents of flooding at critical locations; — Any obvious obstruction to drainage; and — Date and time of flooding. • Coordinate with existing asset management programs. Incorporate data logging and reporting with the CBRM GIS systems.
2. Monitor Performance of New Infrastructure
➢ Rough Order of Magnitude Cost: Operational Budget
• Keep track of operations response required since recent road/storm system upgrades. • Coordinate site review/documentation of new storm system performance by both CBRM and NSTIR Operations Staff during future heavy rainfall events.
3. Ongoing Maintenance & Response
➢ Rough Order of Magnitude Cost: Operational Budget
• Continue response by operations staff to heavy rainfall events • Ongoing preventative maintenance of drainage systems • Review maintenance and flood response activities against risk assessment and floodplain mapping studies to prioritize response.
CBRM NDMP Flood Risk Assessments Page 41 4. Sanitary Sewer System Analysis
➢ Rough Order of Magnitude Cost: $50-300K+ (NDMP Stream 3 – Mitigation Planning)
• In conjunction with ongoing studies related to the municipality’s sanitary sewer system, review the performance of the system in heavy rainfall conditions to identify risk for sewer backup. • Conduct an inflow and infiltration study at each of the major sewer systems within the municipality, particularly those located in close proximity to key streams or stormwater infrastructure (e.g. Renwick Brook sewer) • Plan for prevention measures (e.g. system waterproofing, removal of inflow connections) and/or infrastructure upgrades. • Consider residential/commercial backflow preventers • Consider systems suitable for sewer separation. • Additional benefits in terms of Asset Management, long term Capital Budget Planning, Planning and Development Policy updating, and informing further assessments of the sewer system.
POLICY AND PLANNING STRATEGIES
5. Update Land Use Planning and Development Policies
➢ Rough Order of Magnitude Cost: $25-75K (NDMP Stream 3 – Mitigation Planning)
• Review land use planning regulations to restrict development within defined floodplains, including: — No-build zones; — Defining types of development permitted within flood limits of varying return periods; — Mandatory incorporation of flood protection into new developments near/adjacent floodplains. • Monitor and enforce policies to prevent development and expansion of property in high risk areas. • Consider long term, strategic water-shed level stormwater management objectives through Stormwater Master Planning. • Coordinate with planned and potential new residential developments (e.g. Membertou).
6. Stormwater Policies
➢ Rough Order of Magnitude Cost: $25-75K (NDMP Stream 3 – Mitigation Planning)
• Develop and/or enhance stormwater management policies, including management of stormwater quantity and quality. • Enforce drainage standards (major/minor systems, design-storms). • Monitor and enforce standards and regulations. • Policy for implementation of stormwater management Best Management Practices (BMPs) in new developments. • Consider Low Impact Development (LID) Measures used to mitigate peak flow rates from individual properties and, by extension, mitigate impacts of overall development (e.g. controlled flow roof drains, green roofs, rain gardens and underground storage).
CBRM NDMP Flood Risk Assessments Page 42 EMERGENCY PREPAREDNESS STRATEGIES
7. Community Outreach on Flood Protection and Resiliency
➢ Rough Order of Magnitude Cost: $25-50K (NDMP Stream 3 – Mitigation Planning)
• Public outreach and education for emergency readiness. Raise community awareness on preparation and response. • Development of public information for distribution. Develop a website for easy access to all required information regarding flood awareness. • Encourage homeowners to pursue private property upgrades (e.g. flood-proofing, lot re-grading). • Leverage existing resources: — Partners for Action: https://uwaterloo.ca/partners-for-action — FloodSmart Canada: http://floodsmartcanada.ca/
8. Emergency Preparedness and Response Planning
➢ Rough Order of Magnitude Cost: Operational Budget
• Review emergency detour plans and incorporate identified flood-risk zones into evacuation route planning. • Conduct detailed traffic modelling of emergency routes. • Maintain forecasting and early warning communication systems. • Consider thresholds for evacuation of high-risk areas. • Document flood management plans. • Incorporate detour plans into both preventative and responsive public communication/warning procedures. • Coordinate with NSTIR and Membertou First Nation regarding future roadwork within CBRM.
6.2.4 FUNDING OPPORTUNITIES
The following table provides a brief overview of potential funding opportunities in addition to the federal NDMP that CBRM may wish to investigate further to implement flood mitigation measures:
PROGRAM FUNDING
Flood Risk Infrastructure Investment Cost share – up to 50% Program (FRIP) – 2014 Disaster Mitigation and Adaptation Fund $2 Billion 10 years (2018-2028) (DMAF) – 2018 Cost share – up to 50% with provinces, up to 40% with municipalities Investing in Canada Plan - 2018 $180 M over 12 years (2018-2030) $14 Billion 10 years (2014-2024) ~ $3 Billion available each year for municipal projects New Building Canada Fund – 2014 National Infrastructure Component (NIC): $4 Billion Provincial-Territorial Infrastructure Component (PTIC): $10 Billion
Municipal Asset Management Program $50 M over 5 years (2017-2022) (MAMP) – 2017
Municipalities for Climate Innovation (MCIP) $75 M over 5 years (2017-2023) – 2017
CBRM NDMP Flood Risk Assessments Page 43 7 CONCLUSIONS
7.1 PROJECT SUMMARY
The overall goal of the NDMP Flood Risk Assessments project was to complete flood risk assessments for 5 major watershed areas and develop preliminary mitigation strategies. The purpose of this work was to investigate and define community-wide effects, impacts and risks associated with flooding to inform future decision making. The five major watersheds for review included: Reservoir Brook, Prime Brook, Renwick Brook, Cadegan Brook and Smelt Brook. The Preliminary Risk Assessments process began with an initial review of the five watersheds through a desktop study and review of high-level flood mapping imagery made available for the current study. This was followed by site visits throughout each of the 5 major watersheds with CBRM Engineering and Operations Staff. The visits served to familiarize the project team with each site area, obtain site photos, and gain a historical context of each area and past flooding issues reported to CBRM. Concurrently, ClimAction Services Inc. performed an analysis of current and future climate trends within the municipality. Overall, there is consensus that climate change will bring on more intense and longer rain events and higher sea-levels, which could worsen the impacts of flooding in the municipality. It was recommended that the municipality consider the October 2016 event of a 24-hour, 224mm storm as the current design storm, with a 20% increase for future climate change resulting in a design storm of 269mm. Following the preliminary assessments, the initial results were presented to the municipality and key stakeholders at Workshop No. 1, held on June 25, 2018. The workshop involved representatives from various CBRM departments such as engineering, community and land use planning, operations, environmental control and emergency services, as well as external stakeholders from NSTIR and Membertou First Nation. The Risk Assessment Workshop served to help inform the stakeholders on the process, risk considerations, and climate change impacts, as well as to collect input and feedback on community risk and vulnerabilities through collaborative engagement. The results of the preliminary risk assessment and stakeholder workshop were collected and used to populate a risk inventory table, with the goal of logging identified at-risk infrastructure within the community, particularly along the 5 major watercourses. The detailed risk assessment process involved reviewing and comparing the identified infrastructure and locations for vulnerabilities, risks, and potential solutions to mitigate risk at the site and throughout the community. Prioritization of risk between the five watersheds was conducted to provide a sense of overall risk in various areas of the municipality in comparison to one another. Mitigation strategies for the municipality were developed, including floodplain mapping, structural measures such as culvert replacements, and non-structural measures such as community outreach. The results of the detailed risk assessments and mitigation strategies were presented to CBRM engineering and operations staff at a second workshop, held on February 11, 2019. This workshop served to gain consensus from key stakeholders on risk priorities and proposed mitigation strategies. The workshop clearly identified that community outreach and engagement will play a key role in the flood risk management strategy for the municipality moving forward.
7.2 SUMMARY OF KEY IDENTIFIED FLOOD RISKS
The following table summarizes the results of the flood risk assessment of the five watersheds located within CBRM, as further discussed earlier in section 5.5.
CBRM NDMP Flood Risk Assessments Page 44 Table 3: Summary of Flood Risk by Watershed
WATERSHED KEY OBSERVATIONS / RISK INDICATORS
Reservoir • Primarily undeveloped upper watershed – Consider future development. Brook • City Reservoir – Must remain protected. Consider Potential for flow retention. • Cape Breton Regional Hospital – Appears to be located outside of main risk area. • Membertou Lands – Consider future and existing development north and south of Highway 125. • Rotary Park – Risk identified at dam structure. Consider potential for flow retention. • Residential Area – Steep grades, subject to risks associated with high velocities, erosion and debris generation. • Argyle Street Crossing – Capacity risk identified. Consider assessment and upgrade. • Wentworth Park – Flood inundation potential identified. Consider coastal inundation at outlet and lower reaches.
Prime Brook • Upper watershed partially developed – Consider future development impacts • Some undeveloped green space in upper watershed – Consider potential for flow attenuation • Brook split between Weider Drive and Newlands Ave –consider flow spilt/diversion opportunities paired with infrastructure upgrades. • Lower west branch – steep lower section, evidence of erosion and undermining of structures. • Kings Road crossing at Weidner – Capacity risk identified. Consider assessment and upgrade. • Lower east branch – high risk area with multiple culvert crossings in residential area, uncertain subsurface infrastructure, deteriorated culverts. Consider culvert assessment and replacement program. • Kings Road crossing at Harbourview – appears to traverse private property near homes.
Renwick • Upper watershed partially developed – Consider future development impacts. Brook • Sanitary sewer system located within floodplain – consider operational, environmental, and public health risks. • Past flooding of Cameron Bowl Ballfield and Park – consider infrastructure resiliency and raising community awareness of flood risk. • Park Street Crossing – Potential capacity risk identified. Blockage could potentially result in catastrophic failure of road embankment. Consider structural and capacity condition assessment. Prevent access to pedestrian walkway. • Reserve Street and Commercial Area – located in topographic low area, prone to flooding. Consider local flood study and possible flood protection or relocation of critical infrastructure. Consider influence of downstream restrictions. • Several culvert crossings in residential areas in tributary systems. Recommended culvert condition assessment and replacement program. • Trail Pedestrian Bridge Crossing possibly located within floodplain. Consider assessment for flood resiliency. • Outlet spillway and pedestrian bridge. Consider tidal influence, including future sea level rise and storm surge. • Commercial Street Bridge – perform structural conditions assessment a review with current and future peak tidal conditions. Consider raising the underside of future replacement structure. • High flow volume and velocities in the Renwick Brook System could pose risk to the public. Recommended community outreach to raise awareness of flood risks
Cadegan • Reserve Street situated within natural floodplain. Concerns with overflow into collection system. Potential Brook opportunity for flood water retention, with infrastructure review. • Flooding of mine water treatment facility – consider environmental impacts and impact to private industry. • Recommended culvert condition assessment and replacement program, particularly along Neville Street and Phalen Road. • Confirm capacity of recently replaced structure at Trail Crossing. • Kings Road Crossing identified as high-risk. Perform condition and capacity assessment and plan for structure upgrade. Prepare monitoring and emergency management plan. Blockage could result in potentially catastrophic failure. • High flow volume and velocities in the Cadegan Brook System could pose risk to the public. Recommended community outreach to raise awareness of flood risks.
Smelt Brook • Pottle Lake Reservoir at upper end of the system – Consider opportunity for potential storage and flow retention. • Wilke Drive Crossing – old structure, consider condition assessment and capacity review. • Rail Corridor Crossing – high embankment elevation which could result in serious impacts if culvert is blocks or fails. Recommended condition and capacity assessment. • Pierce Street and Smelt Brook Park – Emergency Services infrastructure located directly within floodplain. Consider relocation and public outreach. • Risk of Coastal inundation at outlet and lower reaches. Consider impacts of storm surge and future sea-level rise which could worsen flood risk. • Coastal infrastructure including Queen Street and packing plant may be located within sea-level rise projections.
CBRM NDMP Flood Risk Assessments Page 45 The cumulation of risk scores within each watershed indicated the following prioritization of watersheds in relation to each other:
Watershed Overall Priority Cumulative Average Risk No. Identified District System Ranking Risk Score Score Risk Sites
Renwick Brook Glace Bay 1 57 1.9 30
Prime Brook Sydney 1 35 2.3 15
Reservoir Brook Sydney 3 32 1.5 21
Cadegan Brook Dominion 4 29 2.1 14
Smelt Brook North Sydney 5 25 2.1 12
The prioritization score can be considered indicative of the overall level of risk within each district, as a tool to direct focus. The prioritization is limited by the scope of the study, influenced by size of watershed and the availability of information. It is expected that following further investigation and assessment, risk priorities may change.
7.3 SUMMARY OF KEY MITIGATION STRATEGY RECOMMENDATIONS
A variety of mitigation strategies were reviewed for potential feasibility for the 5 watersheds in CBRM. These strategies ranged from floodplain mapping, inventory and assessment, structural upgrades, emergency planning and policy development. Based on consultation with municipal engineering and operations staff at the mitigation planning workshop, the following mitigation strategies stood out as top priorities for the municipality: ✓ Culvert condition assessment, inventory and replacement programs. ✓ Identify critical at-risk large structures for upcoming capital projects. ✓ Initiate municipality-wide and/or watershed specific floodplain mapping studies. ✓ Develop municipality-wide flood risk adaptation strategy (non-structural), including flood emergency response, emergency route planning, community engagement, collaboration with stakeholders. Subsequent to this risk assessment and mitigation planning exercise, the following immediate next steps should be taken by the municipality to continue the process of flood risk assessment and mitigation planning: ➢ Scope recommended mitigation projects for upcoming budget planning. ➢ Pursue additional funding opportunities. ➢ Develop a working committee to oversee adaptation strategy planning. With an actively engaged engineering and operations staff leading the way, the Municipality can move forward with a clear vision and plan to help better understand flood risk, and work towards strategies to help mitigate impacts to the community from future flood events in a changing climate.
CBRM NDMP Flood Risk Assessments Page 46
BIBLIOGRAPHY
Addy, S., Cooksley, S., Dodd, N., Waylen, K., Stockan, J., Byg, A. And Holstead, K., 2016. River restoration and biodiversity: nature-based solutions for restoring the rivers of the UK and Republic of Ireland. Aberdeen: Centre for Expertise in Water (CREW). Canada’s Top Ten Weather Stories of 2013. (2013). Ottawa. Retrieved from https://www.ec.gc.ca/meteo- weather/default.asp?lang=En&n=5BA5EAFC-1&offset=2&toc=hide Fisher, G. (2011). Municipal Climate Change Action Plan Guidebook. Service Nova Scotia and Municipal Relations: Halifax, NS. Gippel, C.J., 1995. Environmental hydraulics of large woody debris in streams and rivers. Journal of Environmental Engineering, 121 (5), 388-395. Gurnell, A.M. And Sweet, R., 1998. The distribution of large woody debris accumulations and pools in relation to woodland stream management in a small, low-gradient stream. Earth Surface Processes and Landforms, 23 (12), 1101-1121. Harris, G.L., Clements, R.O., Rose, S.C., Parkin, A. And Shepherd, M., 2004. Review of impacts of rural land use and management on flood generation. Impact study report. Appendix C Current state of managed rural land and mitigation measures. R&D Technical Report FD2114/TR. London: Department for Environment, Food and Rural Affairs. IPCC, 2012: Summary for Policymakers. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 3-21. IPCC, 2013: Summary for Policymakers: In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. James, T.S., Henton, J.A., Leonard, L.J., Darlington, A., Forbes, D.L., and Craymer, M., (2014). Relative Sea-level Projections in Canada and the Adjacent Mainland United States; Geological Survey of Canada, Open File 7737, 72 p. doi:10.4095/295574 Lane, S.N., Brookes, C.J., Hardy, R.J., Holden, J., James, T.D., Kirkby, M.J., Mcdonald, A.T., Tayefi, V. And Yu, D., 2003. Land management, flooding and environmental risk: new approaches to a very old question. Presentation to CIWEM National Conference, September 2003. Palko, K. and Lemmen, D.S. (Eds.). (2017). Climate Risks and Adaptation Practices for the Canadian Transportation Sector 2016. Ottawa, ON: Government of Canada. Palmer, M.A., Lettenmaier, D.P., Poff, N.L., Postel, S.L., Richter, B. And Warner, R., 2009. Climate change and river ecosystems: protection and adaptation options. Environmental Management, 44 (6), 1053-1068. Pattison, I. And Lane, S.N., 2012. The link between land-use management and fluvial flood risk: A chaotic conception? Progress in Physical Geography, 36 (1), 72-92. Quinn, P., O’donnell, G., Nicholson, A., Wilkinson, M., Owen, G., Jonczyk, J., Barber, N., Hardwick N. And Davies, G., 2013. Potential use of runoff attenuation features in small rural catchments for flood mitigation: evidence from Belford, Powburn and Hepscott. Joint Newcastle University, Royal Haskoning and Environment Agency report. Available from: https://research.ncl.ac.uk/proactive/belford/newcastlenfmrafreport/reportpdf/June%20NFM%20RAF% 20Report.pdf [Accessed 11 January 2019].
CBRM NDMP Flood Risk Assessments Page 47
Thanksgiving Floods in Atlantic Canada Caused More Than $100 Million in Insured Damage. (2016). Halifax. Retrieved from https://www.canadianunderwriter.ca/insurance/thanksgiving-floods-atlantic- canada-caused-100-million-insured-damage-catiq-1004103794/ The State of Nova Scotia’s Coast: Technical Report. (2009) Halifax. Retrieved from https://novascotia.ca/coast/documents/report/Coastal-Tech-Report-Nov-09.pdf Timeline: How the Great Flood Of 2013 Evolved. (2013). Calgary. Retrieved from http://calgaryherald.com/news/local-news/timeline-how-the-great-flood-of-2013-evolved Thorne, C.R., Lawson, E.C., Ozawa, C., Hamlin, S.L. And Smith, S.A., 2015. Overcoming uncertainty and barriers to adoption of Blue-Green Infrastructure for urban flood risk management. Journal of Flood Risk Management, DOI: 10.1111/jfr3.12218.
CBRM NDMP Flood Risk Assessments Page 48
APPENDIX
A FIGURES APPENDIX
B RISK INVENTORY TABLE
APPENDIX
C CLIMATE OBSERVATIONS & PROJECTIONS
APPENDIX
D PHOTOGRAPHIC LOG (DIGITAL)
APPENDIX
E NDMP RAIT FORM (DIGITAL) KEY MAP: Newfoundland Québec and Labrador
New Brunswick
$ PROJECT Nova LOCATION Scotia
LEGEND:
Watercourse
Watershed Assessment Area
INDIAN SYDNEY BAY HARBOUR LINGAN BAY
NORTH SITE 4 SYDNEY SITE 5 CADEGAN BROOK GLACE SMELT BROOK BAY µ DISCLAIMER: BIG GLACE THIS DRAWING AND DESIGN IS COPYRIGHT PROTECTED WHICH SHALL BAY LAKE NOT BE USED, REPRODUCED OR REVISED WITHOUT WRITTEN PERMISSION BY WSP CANADA INC.. THE CONTRACTOR SHALL CHECK AND VERIFY ALL DIMENSIONS AND UTILITY LOCATIONS AND REPORT ALL ERRORS AND OMISSIONS PRIOR TO COMMENCING WORK. SOUTH ARM SITE 3 PROJECT: RENWICK BROOK PROJECT: CBRM NDMP RISK ASSESSMENTS OF FLOOD PRONE AREAS
PROPOSAL NO.: 181-03080
CLIENT:
CAPE BRETON REGIONAL MUNICIPALITY
FIGURE: SYDNEY TITLE: OVERVIEW OF 5 CBRM WATERSHEDS FOR FLOOD ASSESSMENTS SITE 1 FIGURE NO.: REVISION NO.: RESERVOIR BROOK 1 0 SCALE: 1:84,000 0 500 1,000 2,000 3,000 4,000 Metres
SITE 2 DATUM: PROJECTION: PRIME BROOK NAD 83 CSRS UTM ZONE 20 NORTH
DRAWN BY: CHECKED BY: T. MOREHOUSE S. LEWIS
CREATED DATE: REVISION DATE: (YYYY-MM-DD) (YYYY-MM-DD) 2018-04-23 2018-04-23
WSP Canada Inc. 1 Spectacle Lake Drive, Dartmouth, Nova Scotia Source: Esri, DigitalGlobe, GeoEye, Earthstar Geographics, CNES/Airbus DS, USDA, USGS, AeroGRID, IGN, and the GIS User www.wsp.com Community Document Path: S:\GIS\2_PROJECTS\2018\181_03080_CBRM_NDMP_FloodRisk_NS\8_MXD\20180423_181_03080_CBRM_NDMP_RiskAssessmentSitesOverview.mxd A B C D E
& 25 !Ñ 40 5 kj !Ñ& 25
C 15 5 ! !Ñ& 35
25 ¬e 5 !Ñ& Hospital Street 30 5 Cartier Street (!1 !Ñ& Herbert Street kj !(2 Atlantic Street Terrace Street 0 !(2 St Peters Road !(2 Whitney Avenue (!2 (!3 C !(2 Union Street Royal Avenue r g: !(2 es 20 c Park Street en 5 Rigby Road t Street 4 (! Cabot Street (!5 5 !(C 25 A 15 ¬e d 5 m 5 ira lt
y 5 1 C 1 ou r t !(Ù
t n 20 15 e c & s !Ñ e r C
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kj Oxford Street 25 5 !(Ù t !(Ù r (! Rockdale Avenue u o C e 10 d g 5 a a o tt R j o s ! C g n i t K e e 15 tr S 0 25 20 l !( 30 t e n m e 5 m c urt e Gra ndvie w Street C s Co Shandwick Street h t K ris e r e t Grove Street top r a e M he C d tr r e S C rd a !(Ù 0 n !( o Harold Street e !Ñ& L !(Ù Kennedy Avenue !(Ù Common Street Colby Street d a o R s G g e n o i 60 rg K !(Ù e 5 d (! S l t O re !(Ù et
s 60 t 65 h g Edgewood Drive i 55 e !(Ù H 65 r Brookview Drive e w o 2 T 2 kj
kj H kj !C ills id e S kj tr 70 ee !Ñ& t kj kj kjkj Stuart Street 65
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PROJECT: FIGURE: LEGEND: PRO JECT: TITLE: DATUM: LAND USE Reservoir Brook (SITE 1) RESERVOIR BROOK CBRM NDMP RISK ASSESSMENT NAD 83 CSRS !j !(M WATERSHED Auto Sales Government OF FLOOD PRONE AREAS PRO JECTI ON: Elevation Contours (5 metre Interval) !(Ù Sports Field !C Health Care UTM ZONE 20 NORTH PRO JECT N O.: FIGURE NO.: REVISION NO.: 0 DRAWN BY: _` Outfall !( Cemetery a Public Protection 181-03080 A1 0 !(C Cenotaph !Ñ& Religious T. MOREHOUSE Watershed CLIENT: WSP Canada Inc. CHECKED BY: Watercourse ¬e Resource Centre g: CAPE BRETON REGIONAL MUNICIPALITY 1 Spectacle Lake Drive, Electrical Substation (CBRM) Dartmouth, Nova Scotia S. LEWIS Property Boundary kj Utility μ www.wsp.com CREATED DATE: ")H (YYYY-MM-DD) \ \ Helipad \\\\\Wetland DISCLAIMER: !(2 Park THIS DRAWING AND DESIGN IS COPYRIGHT PROTECTED WHICH SHALL NOT BE USED, REPRODUCED OR REVISED WITHOUT WRITTEN PERMISSION BY WSP CANADA INC.. 2019-03-06 THE CONTRACTOR SHALL CHECK AND VERIFY ALL DIMENSIONS AND UTILITY LOCATIONS AND REPORT ALL ERRORS AND OMISSIONS PRIOR TO COMMENCIN G W OR K. REVISION DATE: SCALE: 1:5,000 SOURCE: (YYYY-MM-DD) 0 50 100 200 300 400 500 600 Me tre s 2019-03-06 A B C D E
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A B C D E
PROJECT: FIGURE: LEGEND: PRO JECT: TITLE: DATUM: LAND USE Prime Brook (SITE 2) CBRM NDMP RISK ASSESSMENT PRIME BROOK j M WATERSHED NAD 83 CSRS ! Auto Sales !( Government OF FLOOD PRONE AREAS PRO JECTI ON: Elevation Contours (5 metre Interval) !(Ù Sports Field !(Ö Hall UTM ZONE 20 NORTH PRO JECT N O.: FIGURE NO.: REVISION NO.: 0 DRAWN BY: _` Outfall !( Cemetery !C Health Care 181-03080 A2 0 2 T. MOREHOUSE Watershed !( Park a Public Protection CLIENT: WSP Canada Inc. CHECKED BY: Watercourse !Ñ& Religious CAPE BRETON REGIONAL MUNICIPALITY 1 Spectacle Lake Drive, (CBRM) Dartmouth, Nova Scotia S. LEWIS Property Boundary kj Utility μ www.wsp.com CREATED DATE: \ (YYYY-MM-DD) \\\ Wetland DISCLAIMER: \ \\ THIS DRAWING AND DESIGN IS COPYRIGHT PROTECTED WHICH SHALL NOT BE USED, REPRODUCED OR REVISED WITHOUT WRITTEN PERMISSION BY WSP CANADA INC.. 2019-03-06 THE CONTRACTOR SHALL CHECK AND VERIFY ALL DIMENSIONS AND UTILITY LOCATIONS AND REPORT ALL ERRORS AND OMISSIONS PRIOR TO COMMENCIN G W OR K. REVISION DATE: SCALE: 1:5,000 SOURCE: (YYYY-MM-DD) 0 50 100 200 300 400 500 600 Me tre s 2019-03-06 A B C D E !(Ù
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PROJECT: FIGURE: LEGEND: PRO JECT: TITLE: DATUM: LAND USE Renwick Brook (SITE 3) CBRM NDMP RISK ASSESSMENT RENWICK BROOK WATERSHED NAD 83 CSRS !C Health Care a Public Protection OF FLOOD PRONE AREAS PRO JECTI ON: Elevation Contours (5 metre Interval) !Ñ& Religious nm School UTM ZONE 20 NORTH PRO JECT N O.: FIGURE NO.: REVISION NO.: M DRAWN BY: _` Outfall !( Government kj Utility 181-03080 A3 0 \\ \\ \ !(Ù T. MOREHOUSE Wetland (! Sports Field CLIENT: \ WSP Canada Inc. CHECKED BY: Watershed Boundary !(0 Cemetery CAPE BRETON REGIONAL MUNICIPALITY 1 Spectacle Lake Drive, (CBRM) Dartmouth, Nova Scotia S. LEWIS Watercourse μ www.wsp.com CREATED DATE: g: Vacant Electrical Generating Station (YYYY-MM-DD) Property Boundary DISCLAIMER: THIS DRAWING AND DESIGN IS COPYRIGHT PROTECTED WHICH SHALL NOT BE USED, REPRODUCED OR REVISED WITHOUT WRITTEN PERMISSION BY WSP CANADA INC.. 2019-03-06 THE CONTRACTOR SHALL CHECK AND VERIFY ALL DIMENSIONS AND UTILITY LOCATIONS AND REPORT ALL ERRORS AND OMISSIONS PRIOR TO COMMENCIN G W OR K. REVISION DATE: SCALE: 1:5,000 SOURCE: (YYYY-MM-DD) 0 50 100 200 300 400 500 600 Me tre s 2019-03-06 A B C D E !(0
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A B C D E
PROJECT: FIGURE: LEGEND: PRO JECT: TITLE: DATUM: LAND USE CADEGAN BROOK Cadegan Brook (SITE 4) CBRM NDMP RISK ASSESSMENT NAD 83 CSRS Ù WATERSHED !Ñ& Religious !( Sports Field OF FLOOD PRONE AREAS PRO JECTI ON: Elevation Contours (5 metre Interval) a Public Protection !(0 Cemetery UTM ZONE 20 NORTH PRO JECT N O.: FIGURE NO.: REVISION NO.: Remediation Site DRAWN BY: _` Outfall nm School R 181-03080 A4 0 &- (Former Mine Workings) T. MOREHOUSE kj Utility CLIENT: Watercourse CHECKED BY: \ \ WSP Canada Inc. \ Wetland g: Electrical Substation CAPE BRETON REGIONAL MUNICIPALITY 1 Spectacle Lake Drive, \\ \ (CBRM) Dartmouth, Nova Scotia S. LEWIS Watershed Boundary μ www.wsp.com CREATED DATE: (YYYY-MM-DD) DISCLAIMER: Property Boundary THIS DRAWING AND DESIGN IS COPYRIGHT PROTECTED WHICH SHALL NOT BE USED, REPRODUCED OR REVISED WITHOUT WRITTEN PERMISSION BY WSP CANADA INC.. 2019-03-06 THE CONTRACTOR SHALL CHECK AND VERIFY ALL DIMENSIONS AND UTILITY LOCATIONS AND REPORT ALL ERRORS AND OMISSIONS PRIOR TO COMMENCIN G W OR K. REVISION DATE: SCALE: 1:5,500 SOURCE: (YYYY-MM-DD) 0 50 100 200 300 400 500 600 Me tre s 2019-03-06 A B C D E
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A B C D E
PROJECT: FIGURE: LEGEND: PRO JECT: TITLE: DATUM: Smelt Brook (SITE 5) LAND USE CBRM NDMP RISK ASSESSMENT SMELT BROOK WATERSHED NAD 83 CSRS !(0 nm OF FLOOD PRONE AREAS PRO JECTI ON: Elevation Contours Cemetery School (5 metre Interval) !Ñ& Religious kj Utility UTM ZONE 20 NORTH PRO JECT NO .: FIGURE NO.: REVISION NO.: DRAWN BY: _` Outfall !(Ù 181-03080 A5 0 a Public Protection (! Sports Field
T. MOREHOUSE Watershed Area CLIENT: !( Landfill WSP Canada Inc. CHECKED BY: Property Boundary CAPE BRETON REGIONAL MUNICIPALITY 1 Spectacle Lake Drive, (CBRM) Dartmouth, Nova Scotia S. LEWIS μ www.wsp.com CREATED DATE: (YYYY-MM-DD) DISCLAIMER: THIS DRAWING AND DESIGN IS COPYRIGHT PROTECTED WHICH SHALL NOT BE USED, REPRODUCED OR REVISED WITHOUT WRITTEN PERMISSION BY WSP CANADA INC.. 2019-03-06 THE CONTRACTOR SHALL CHECK AND VERIFY ALL DIMENSIONS AND UTILITY LOCATIONS AND REPORT ALL ERRORS AND OMISSIONS PRIOR TO COMMENCING WORK. REVISION DATE: SCALE: 1:5,000 SOURCE: (YYYY-MM-DD) 0 50 100 200 300 400 500 600 Me tre s 2019-03-06 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
‐ Overtopped in October 2016 flood ‐ Known capacity limitations and risk of blockage from debris. Replacement planned. Upsizing Recommended. ‐ One of three crossings to downtown Sydney, alternative routes available ‐ High flow volumes during peak events Rectangular Concrete Box, Known capacity ‐ CBRM is planning structural upgrades ‐ Possibility for deep building of water behind road embankment during Reservoir Brook 5 Argyle Street Bridge Retaining wall, and Control 3 restriction ‐ Concrete weir controls flow out of most upstream pond in Wentworth Park blockage/capacity restriction. Presents risk of catastrophic road embankment Weir System system. failure. ‐ Located just upstream of bandstand. ‐ Dam structure retains upstream pond in rotary park ‐ Visibly aging structure. Dam condition assessment and plan for replacement. Consider ‐ Reportedly, dam held in 2016 event but was close to overtopping ‐ Dam failure could result in release of high volume of water and debris, posing storage opportunity and variable flow control in system upgrade. Stone/concrete dam and Aged structure, signs of Reservoir Brook 8 Rotary Park Dam ‐ Hospital Sewer system runs under the pond additional risks and impacts downstream. 3 weir structure deterioration ‐ Opportunity to utilize storage potential in park ponds for flow attenuation in peak events. ‐ Located at outlet of Wentworth Park ‐ High flow volumes during peak events. Condition & Capacity Assessment including Sea‐Level Rise and Storm Kings Road Bridge at Wentworth Reservoir Brook 1 Concrete Box ‐ Tidal influence ‐ Wentworth park pond upstream provides some retention, however tidal 2 Surge Park ‐ Kings Road is a major transportation route. influence could risk road overtopping depending on elevation. ‐ Multiple culverts pass under bandstand structure. ‐ Bandstand and culverts located in a topographic low area, susceptible to flooding Acceptance of periodic flooding of park. Wentworth Park Bandstand Box Reservoir Brook 4 Multiple Box Culverts Planned upgrade ‐ Area flooded in the past in peak events. 2 Structural assessment for flood resiliency. Culvert System ‐ Box Culverts upgrades in recent years. ‐ Known flooding location, consider resiliency to flooding. ‐ Exposed pipe crossing at bridge. ‐ Small wooden structure in close proximity to the brook. Likely susceptible to Review alternative crossing locations on higher ground to increase Steep Brook Section, ‐ Small structure appears to have minimal resiliency to flooding. impact from high flow velocities in peak event. clearance from flood waters. Wooden structure in Renwick Brook near S. Bentinick Wooden Pedestrian Bridge, ‐ High frequency of help desk calls in this area ‐ Consider risk of downstream blockage in event of bridge failure. Raise public awareness on known risk of pedestrian crossing flooding. Reservoir Brook 6 close proximity to brook. 2 Street concrete abutments, gabion ‐ Steep channel section, high flow velocities. Risk of bank erosion and debris Consider pipe protection and/or relocation to avoid impact of high Exposed pipe crossing. walls. generation. flow velocities/impact from debris.
‐ Weir outlet controls flows from the reservoir. ‐ Failure of the reservoir outlet could result in release of high volume of water to Condition assessment to verify structural integrity if reservoir outlet ‐ Downstream 4x Culverts cross treatment facility access road. downstream system, with subsequent risks and impacts downstream. weir. Consider upgrade to increase retention potential in flood Weir Outfall & 4x HDPE ‐ Treatment facility infrastructure located in topographic low area. ‐ Risk of limited access to treatment facility in road washout at 4 x culverts events. Reservoir Brook 16 City Reservoir Outlet Signs of deterioration 2 Culverts Add additional protections to access road crossing culverts and consider raising road bed to secure access to treatment facility in flood events. Churchill Drive Crossing West of Big ‐ Located on Membertou First Nation Lands ‐ Capacity restriction Condition and capacity assessment. Reservoir Brook 34 Box Culvert Not reviewed 2 Noel Ekel ‐ Reported backup at Churchill Drive ‐ 330‐340 houses ‐ Reported residential lot drainage issues Membertou First Nation Engineering staff aware and taking measures ‐ Reported ~70 basement floods ‐ Reported cases of sewer backup to mitigate risks. Ongoing cooperation between Membertou and ‐ Adjacent residential sewer back up issues CBRM. ‐ High help desk call frequency Residential Development (Bradley Reservoir Brook Site Community ‐ Mainly separated sanitary/storm systems. 2 Street, Maliktut Court) ‐ Operations staff currently assessing back flow installed. ‐ Engineering staff are aware of lot grading issues related to stormwater drainage, which are being dealt with and addressed for future development. ‐ Development and grown planned for the area. ‐ Residential areas along Gallagher and MicMac Streets ‐ Impacts to residential homes Consider feasibility of deep storm sewer in coordination with ‐ Shallow sanitary sewer, identified by Operations staff as not deep enough to ‐ Staff flagged need for deep storm sewer Membertou First Nation. Also consider other flood mitigation Reservoir Brook Site Gallagher Street & MicMac Street Community Not reviewed service the development. 2 alternatives. ‐ New deep sewer required along Gallagher street.
‐ Located in Wentworth Park, between two ponds. ‐ High flow volumes during peak events. Wentworth park pond upstream provides Review with downstream Kings Road Bridge crossing. Condition & Bentinck Street Bridge at Concrete Bridge & Control ‐ Downstream pond subject to tidal influence some retention but weir could be overtopped in high flow conditions. Capacity Assessment including Sea‐Level Rise and Storm Surge. Reservoir Brook 2 1 Wentworth Park Weir ‐ Weir structure controls water levels in upstream pond. ‐ Risk associated with both upstream flows or downstream tidal influence, depending on elevation. ‐ CN Rail owned. ‐ High flow volumes during peak events. Condition & Capacity Assessment Reservoir Brook 3CN Rail Crossing at Wentworth Park Dual Concrete Box Aged structure ‐ Water levels equal upstream and downstream under normal conditions. ‐ Consider structure age for risk of failure. 1 ‐ Wentworth park pond upstream provides some retention. Churchill Drive Culvert north of ‐ Relatively recent construction of Churchill Drive expansion on Membertou First ‐ Newer structure, expectation that design would have accounted for 100 year Confirm flow capacity Reservoir Brook 9 Large Dia. Concrete Culvert Recent upgrade 1 intersection to Hospital Nation Lands. peak event. Churchill Drive Culvert near ‐ Relatively recent construction of Churchill Drive expansion on Membertou First ‐ Newer structure, expectation that design would have accounted for 100 year Confirm flow capacity Reservoir Brook 11 Large Dia. Concrete Culvert Recent upgrade 1 Maliktuk Crescent Nation Lands. peak event. ‐ Relatively recent construction of Churchill Drive expansion on Membertou First ‐ Recent upgrade, low risk in comparison to other structures in the system. Confirm flow capacity Reservoir Brook 12 Bradley Street Extension Culvert Large Dia. Concrete Culvert Recent upgrade 1 Nation Lands. ‐ Relatively recent construction as part of Highway 125 upgrade. ‐ Newer structure, expectation that design would have accounted for 100 year Confirm flow capacity and review inlet protection measures Highway 125 Westbound Churchill Reservoir Brook 13 Large Dia. Concrete Arch Recent upgrade ‐ NSTIR Owned peak event. 1 Drive Off‐Ramp Culvert ‐ Previously reported inlet protection issues ‐ Relatively recent construction as part of Highway 125 upgrade. ‐ Newer structure, expectation that design would have accounted for 100 year Confirm flow capacity and review inlet protection measures Highway 125 Culvert at Churchill Reservoir Brook 14 Large Dia. Concrete Arch Recent upgrade ‐ NSTIR Owned peak event. 1 Drive Exit ‐ Previously reported inlet protection issues
Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 1 of 10 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
‐ Relatively recent construction as part of Highway 125 upgrade. ‐ Newer structure, expectation that design would have accounted for 100 year Confirm flow capacity and review inlet protection measures Highway 125 Eastbound Churchill Reservoir Brook 15 Large Dia. Concrete Arch Recent upgrade ‐ NSTIR Owned peak event. 1 Drive On‐Ramp Culvert ‐ Previously reported inlet protection issues Membertou Street at Tupsi Drive ‐ Located on Membertou First Nation Lands ‐ Staff noted the culverts were less of a concern in comparison to other structures Condition & Capacity Assessment Reservoir Brook 36 3 x Culverts Not reviewed 1 Crossing on the system ‐ Located on higher ground, therefore does not appear to be at risk ‐ Hospital is critical infrastructure, however does not appear to be within known Review flood risk of emergency routes and hospital access. Reservoir Brook Site Cape Breton Regional Hospital Hospital 1 floodplain. ‐ Membertou Expansion, New Developments planned on north and south side of ‐ Storm drainage must be considered in the design of new infrastructure. Coordinate with Membertou First Nation to consider storm drainage Highway 125, Approximately 1400 people ‐ Increase in impervious areas will result in increased runoff to the brook system, mitigation in planning and Development Policies. Consider LID Reservoir Brook Site Membertou Expansion New Development Proposed ‐ Proposed sanitary sewer to cross highway to existing hospital sewer which could result in higher stream flows downstream 1 measures, Inlet control, etc.. Coordinate sewer upgrades as part of ‐ Increased sanitary flows could put pressure on existing sanitary sewer capacity. master planning process.
‐ Shipyard Elementary School ‐ Staff noted the school would only be at risk if the pond was blocked Investigate flood risk potential Reservoir Brook Site Shipyard Elementary School School Building ‐ Located on higher ground. ‐ Vulnerable population (children) 1
‐ Opportunity to utilize storage potential in park ponds for flow attenuation in peak ‐ Unknown risk Condition and capacity assessment. Reservoir Brook 7 Rotary Park Trail Crossing Unknown Structure Not reviewed events. ‐ Risk at a trail crossing is lower than key transportation routes, however failure of Unknown a trail structure could lead to downstream consequences. ‐ Residential homes located upstream. ‐ Unknown risk Condition and capacity assessment. Reservoir Brook 10 Churchill Drive Trail Crossing Unknown Structure Unknown ‐ Risk at a trail crossing is lower than key transportation routes, however failure of Unknown a trail structure could lead to downstream consequences. Churchill Drive Culvert near ‐ Part of Membertou First Nation Churchill Drive expansion and development Unknown Confirm flow capacity Reservoir Brook 17 Concrete Culvert Recent upgrade Unknown Churchill Drive Trail Reservoir Brook 18 Structure Unknown Structure Recent upgrade ‐ Part of Membertou First Nation Churchill Drive expansion and development Unknown Unknown Confirm flow capacity Reservoir Brook 19 Structure Unknown Structure Recent upgrade ‐ Part of Membertou First Nation Churchill Drive expansion and development Unknown Unknown Confirm flow capacity Hospital Parking Access Driveway ‐ Not reviewed in detail Unknown Condition and capacity assessment. Reservoir Brook 20 Unknown Structure Not reviewed Unknown Crossing ‐ Not reviewed in detail Unknown Consultation with NSTIR to confirm condition and capacity. Reservoir Brook 21 Highway 125 Crossing near Hospital Arch Culvert Not reviewed Unknown ‐ Staff noted that NSTIR highway systems to slow flow of water Reservoir Brook 22 Parkview Drive Crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Reservoir Brook 23 Fergusson Drive Crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Reservoir Brook 24 Mullers Lane Crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. George Street Near Gerards Lane ‐ Not reviewed in detail Unknown Condition and capacity assessment. Reservoir Brook 25 Unknown Structure Not reviewed Unknown Crossing ‐ Not reviewed in detail Unknown Condition and capacity assessment. Private Crossing near MacDonald Reservoir Brook 26 Unknown Structure Not reviewed ‐ Possibly privately owned Unknown Lane at George Street ‐ Not reviewed in detail Unknown Consultation with NSTIR to confirm condition and capacity. Highway 125 Westbound Off‐Ramp Reservoir Brook 27 Unknown Structure Not reviewed ‐ NSTIR owned Unknown at George Street Crossing Highway 125 at George Street ‐ Not reviewed in detail Unknown Consultation with NSTIR to confirm condition and capacity. Reservoir Brook 28 Unknown Structure Not reviewed Unknown Crossing ‐ NSTIR owned ‐ Not reviewed in detail Unknown Consultation with NSTIR to confirm condition and capacity. Highway 125 Eastbound Off‐Ramp ‐ NSTIR owned Reservoir Brook 29 at George Street/Reservoir Access Unknown Structure Not reviewed Unknown Road Crossing
Reservoir Brook 30 Rotary Park Trail Crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Reservoir Brook 31 Rotary Park Trail Crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Churchill Drive Crossing East of Big ‐ Located on Membertou First Nation Lands Unknown Condition and capacity assessment. Reservoir Brook 32 Unknown Structure Not reviewed Unknown Noel Ekel ‐ Located on Membertou First Nation Lands Unknown Condition and capacity assessment. Reservoir Brook 33 Trail Crossing at Veterans Ave. Unknown Structure Not reviewed Unknown Membertou Street Crossing ‐ Located on Membertou First Nation Lands Unknown Condition and capacity assessment. Reservoir Brook 35 between Micmac Cr. and Gallagher Unknown Structure Not reviewed Unknown St. ‐ Not reviewed in detail Unknown Condition and capacity assessment. Highway 125 Crossing between Reservoir Brook 37 Unknown Structure Not reviewed ‐ NSTIR owned Unknown Alexandra and Churchill Drive Exits Crossing at Power Station Access ‐ Not reviewed in detail ‐ Unknown Risk Unknown Reservoir Brook 38 Driveway in Membertou expansion Unknown Structure Not reviewed ‐ Coordinate with NSPI ‐ Consider access to power substation Unknown area Reservoir Brook Site Membertou Street Site Not reviewed ‐ Staff identified that Membertou Street requires a storm sewer system. ‐ Poor stormwater drainage Unknown Planned storm sewer installation
Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 2 of 10 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
‐ Inlet is located behind residential homes. ‐ Risk level considers the possibility of structure being located below private Condition and capacity assessment. Investigate and locate structure Prime Brook 3 Inlet to Castle Drive Crossing Unknown Structure Unknown 3 ‐ Structure routing and condition is not well understood. property, and unknown condition. routing. ‐ Inlet is visible on southwest side of Castle Drive but outlet appears to cross private ‐ Risk level considers the possibility of structure being located below private Condition and capacity assessment. Investigate and locate structure Prime Brook 4 Castle Drive Crossing Unknown Structure Not reviewed property property, and unknown condition. 3 routing. ‐ Structure routing and condition is not well understood. ‐ Culvert reported in poor condition ‐ Close proximity to residential homes. Condition & Capacity Assessment. Plan for replacement. Prime Brook 7 Buckingham Drive Crossing Culvert Poor ‐ Possible risk of structure failure/road overtopping from debris or lack of capacity. 3
‐ Culvert reported in poor condition ‐ Known capacity and condition risks. Condition & Capacity Assessment. Plan for replacement. ‐ Reported capacity issues in 2016 Prime Brook 9 Boulderwood Drive Crossing Culvert Poor 3 ‐ Possible alignment on private property/under structures ‐ High frequency of help desk calls in this area ‐ Culvert and channel not well defined, heavily vegetated. ‐ Risk of road flooding due to culvert capacity restriction/failure. Condition & Capacity Assessment ‐ Culvert in poor condition. ‐ Potential impeded access to homes on Oakwood Cres. And Calder Ct. Prime Brook 10 Newlands Ave. Crossing ‐ Upper Culvert Poor ‐ Reported issues with residential sewer backup 3 ‐ Adjacent residential sewer back up issues ‐ High frequency of help desk calls in this area. ‐ High frequency of help desk calls in this area. ‐ Likely capacity restriction at King's Road Culvert Condition & Capacity Assessment. Plan for future upgrade, consider ‐ Channel located immediately behind homes. Staff reported that flow was in close ‐ Steep channel upstream, high velocities, possibility of debris generation which potential opportunity for flow diversion. Upstream channel proximity to homes during 2016 flood event. could further risk blockages at the culvert. stabilization and protection required. ‐ Stabilization of banks performed in the past. ‐ Risk to adjacent homes, structures, properties Kings Road Crossing at Weidner Past failure. Capacity ‐ Residential propane storage tanks located near the brook. ‐ Risk to public safety due to high flow velocities Prime Brook 14 Box Culvert 3 Drive restriction flagged. ‐ Consider water line along Kings Road. Was exposed in 2016 flood event. ‐ Culvert capacity restriction or blockage could result in road overtopping or risk of ‐ Opportunity for flow diversion in upper reaches of Prime Brook to send more flow blowout. in this direction, if channel and structure upgrades can be completed. ‐ Kings Road is a key transportation route (NSTIR owned).
‐ Not reviewed in detail ‐ Culvert failure or blockage could impact Kings Road Condition & Capacity Assessment Prime Brook 24 Kings Road near Kingswood Drive Culvert Aged structure 3 ‐ Staff noted aged culvert crossing Kings Road Crossing at Harbourview ‐ Inlet location behind residential property ‐ Flood Risk at Kings Road if capacity exceeded or blocked. Condition & Capacity Assessment Prime Brook 2 Concrete Box Culvert 2 Drive ‐ Kings Road is a key transportation route ‐ Not reviewed in detail ‐ Close proximity to residential homes. Condition and capacity assessment. Consider options for daylighting Prime Brook 5 Moxham Drive Crossing Unknown Structure Not reviewed 2 ‐ Structure appears to cross under private property. the system in this area. ‐ 1 of 2 culverts was upgraded ‐ Close proximity to residential homes. Condition & Capacity Assessment Prime Brook 6 Newlands Ave. Crossing ‐ Lower Culvert ‐ Crossing at sharp diagonal across the road. ‐ Possible risk of structure failure/road overtopping from debris or lack of capacity. 2 ‐ Reported adjacent residential sewer back up issues ‐ Staff reported that the culverts crossing is in poor condition: structure previously ‐ Risk due to poor structure condition. Coordinate with CN to perform Condition & Capacity Assessment and damaged but not fixed by CN ‐ Consider storm surge and sea level rise impacts plan for rehabilitation/upgrade. Prime Brook 15 Rail Crossing South of Kings Road 3 x Culverts Poor ‐ Access road to the culvert was upgraded ‐ Risk of overtopping CN rail in event of structure failure 2 ‐ Adjacent commercial business ‐ Downstream commercial property could be at risk of impacts from structure failure/rail overtopping. ‐ Low‐lying area behind homes on Calderwood Drive ‐ Surface flooding near residential homes Requires watershed analysis and field investigation to further ‐ Prime Brook splits in 2 directions in this area ‐ Poor subsurface drainage understand flow split. Consider opportunities to re‐direct and/or ‐ Soil is peat in this area. Subsurface drainage issues identified. ‐ Unmanaged flow split, resulting in uncertainty in flows in each downstream store peak flows (with required downstream infrastructure Prime Brook, south of Calderwood Prime Brook Site Flow Split ‐ Staff identified opportunity to control the flow split to manage flows to problem tributary 2 upgrades). Drive areas of the downstream system. ‐ Adjacent residential sewer back up issues ‐ High frequency of help desk calls in this area ‐ Reported residential basement flooding and sewer back up issues ‐ Residential sewer backup and basement flooding System analysis and upgrades Prime Brook Site Fatima Drive Neighborhood Not reviewed ‐ I/I issues 2 ‐ Flow meters in designated area to monitor flow ‐ Past failure, Marlborough Drive was overtopped ‐ Close proximity to residential homes. Condition & Capacity Assessment ‐ Structure recently replaced. Shallow height because of proximity of sanitary ‐ Risk is considered lower than other structures on this system, due to recent Prime Brook 8 Marlbourough Drive Crossing Culvert Recently replaced sewer. upgrade. 1 ‐ Reported adjacent residential sewer back up issues ‐ High frequency of help desk calls in this area ‐ Staff flagged poor stormwater drainage on Oakwood Crescent cul‐de‐sac. ‐ Poor drainage issues sound to be localized and non‐threatening to public safety. Further investigation of drainage concerns is required to fully identify Prime Brook Site Oakwood Crescent Street (cul‐de‐sac) New ‐ Newly constructed street and storm sewer Further investigation required. 1 the risk. Consider remedial measures to storm system if required. ‐ Concerns with stormwater being routed down driveways ‐ Not reviewed in detail ‐ Tidal influence, sea‐level rise and storm surge Condition and capacity assessment. Prime Brook 1CN Rail Crossing Unknown Structure Not reviewed Unknown ‐ CN Rail Property Prime Brook 11 Weidner Drive Crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Prime Brook 12 Kenwood Drive Crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment.
Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 3 of 10 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
‐ Reported high flows but appear to be adequately conveyed through Highway Unknown Consultation with NSTIR to confirm condition and capacity. culverts Prime Brook 13 Hwy 125 Crossing Culvert Not reviewed Unknown ‐ No development planned upstream ‐ Consider possible area upstream of highway for retention ‐ Special Care Facility located on Alexandra Street ‐ Unknown flood risk Investigate flood risk potential Prime Brook Site Special Care Facility Building/Facility Unknown ‐ Vulnerable Population ‐ Prime Brook traverses urbanized residential area through a series of open ‐ Proximity to residential homes risks property damage as well as risk to public Culvert condition assessment and replacement program. System‐wide channels and culvert crossings, from Oakwood Crescent to Harbourview Drive safety in high flow events. study to identify capacity restrictions and risks. Consider flow ‐ Highly vocal community, political attention ‐ Risk of culvert failure/blockages for structures in disrepair or under capacity, diversion at Calderwood Drive (with infrastructure upgrades). Prime Brook ‐ Oakwood Crescent to See Prime Brook Site Open Channel ‐ Subsurface soil is peat, poor drainage, which was not considered in planning. which could result in subsequent road washout Consider sewer backup issues and sewer separation in this area. Harbourview Drive structures ‐ Adjacent residential sewer back up issues Consider lot drainage and stormwater management plans for new ‐ Lot drainage/grading plans not currently required in new development areas. developments
Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 4 of 10 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
‐ Timber structure. ‐ Crossing flagged as likely capacity restriction and risk for blockages from debris. Condition & Capacity Assessment, Recommended priority upgrade, ‐ Backup in past flood event following failure of upstream structure, resulting in ‐ High flow volume and velocity witnessed in this area including upsizing. imact and failure of wing walls. ‐ Culvert restriction has resulted in deep water backup upstream of the road Main Street/Kings Road Box Culvert ‐ Water rose nearly to roadway (deep) but did not overtop road. embankment, which poses risk of catastrophic failure Cadegan Brook 2 Wooden Box Culvert 3 near Cadegan Drive ‐ Wingwalls were re‐done ‐ Public safety risk from high flood waters, velocities and risk of failure ‐ High frequency of help desk calls in this location ‐ Significant re‐routing of emergency services and traffic in the event of ‐ Kings Road/Main Street is key transportation route and emergency access in this failure/road closure. area. Re‐routing is a significant detour. ‐ Abandoned Railway Trail crossing. ‐ Now at risk of being undersized due to improvements upstream Condition & Capacity Assessment ‐ Collapsed and caused debris to travel downstream, causing blockage at Kings ‐ Kings Road is critical ‐ emergency route/long detour Main Trail Crossing at Cadegan Cadegan Brook 5 Concrete Culvert Recently replaced Road Culvert. 3 Brook ‐ Replaced and upgraded after washout ‐ Swampy area upstream with potential capacity for water detention ‐ NSTIR owned ‐ Past issues with structure identified Coordinate Condition & Capacity Assessment with NSTIR Signs of deterioration, Cadegan Brook 10 Neville Street crossing, north Corrugated Metal Culvert ‐ Visible deterioration of CSP culvert ‐ Risk considers long re‐routing for emergency services and traffic if road 3 recent inlet upgrade ‐ Inlet recently extended and upgraded compromised due to structure failure/road flooding. Heavy sediment and ‐ NSTIR owned ‐ Long re‐routing for emergency services and traffic if road were compromised due Coordinate Condition & Capacity Assessment with NSTIR Cadegan Brook 11 Neville Street crossing, south Corrugated Metal Culvert 2 overgrown to structure failure/road flooding. ‐ CBRM planned station upgrade ‐ Environmental risks from SSO Planned Upgrade Phalen Road crossing near Culvert and Sanitary Booster Cadegan Brook 12 Planned upgrade ‐ Overflow to natural environment ‐ Sanitary sewer collection issues 2 Beechwood Drive Station ‐ I/I issues in the local collection system ‐ Existing floodplain/wetland area on either side Reserve Street; Natural retention ‐ Box culvert has minimal available clearance, likely to become inundated during a Condition and capacity assessment. Plan alternative emergency Reserve Street crossing between system. ‐ ‐ Consider opportunities to obtain additional storage capacity (consider flood. routes. Conduct analysis to delineate floodplain. Cadegan Brook 13 Concrete Box Culvert Minimal clearance 2 Haulage Road and Fraser St. required road upgrades). ‐ Risk of road flooding, depending on available upstream storage.
Phalen Road crossing near Reserve ‐ Adjacent residential sewer back up issues ‐ Not easily visible. Some uncertainty in condition. Condition & Capacity Assessment Cadegan Brook 14 Culvert 2 Street, north ‐ High frequency of help desk calls in this area ‐ Risk rating considers uncertainty and help desk frequency. McLeod's Road crossing near ‐ High frequency of help desk calls in this area ‐ Not easily visible. Some uncertainty in routing/condition. Condition & Capacity Assessment Cadegan Brook 18 Culvert Not visible 2 Dominion Street north ‐ Risk rating considers uncertainty and help desk frequency. McLeod's Road/Dominion Street ‐ High frequency of help desk calls in this area ‐ Not easily visible. Some uncertainty in routing/condition. Condition & Capacity Assessment Cadegan Brook 19 Culvert Not visible 2 crossing ‐ Appears to cross private property ‐ Risk rating considers uncertainty and help desk frequency. ‐ Reportedly operations were not impacted in 2016 event, however there has been ‐ Environmental risk ‐ SSOs to wetland in wet weather Sanitary system evaluation, sewershed‐wide I/I reduction. Consider Sanitary Pump Station at Reserve visible evidence of SSOs from the station. ‐ I/I concerns at PS controls to reduce risk of SSOs pose to the environment. Cadegan Brook Site Sanitary Pump Station 2 Street ‐ Sanitary sewer overflows to wetland when capacity exceeded
‐ Residential Flooding reported in 2016 ‐ Residential flooding reported Investigate flooding issues and determine role of CBRM infrastructure ‐ Low‐lying area, adjacent wetland ‐ Close proximity to wetland Cadegan Brook Site Deanna Drive Neighborhood Not reviewed 2 ‐ Reported residential sewer back up issues ‐ High frequency of help desk calls in this area ‐ Residential flooding ‐ Residential flooding reported Investigate flooding issues and determine role of CBRM infrastructure Cadegan Brook Site Haulage Road Neighborhood ‐ High frequency of help desk calls in this area 2 ‐ Manholes discharge to ditches Water Booster Station at Reserve ‐ Staff reported that the station is situated above known flood elevation. ‐ Critical infrastructure, key to public health Review flood risk and resiliency Cadegan Brook Site Water Booster Station 1 Street '‐ No issues identified in 2016 event ‐ Situated at a high elevation in relation to the brook, outside known flood ‐ No imminent flood risk flagged, but critical infrastructure and environmental Operational considerations (I/I, CSOs) elevation considerations. Cadegan Brook Site Treatment Plant Treatment Plant 1 ‐ I/I issues within the sewer shed ‐ Deep outfall, extends into Harbour. No reported issues. Cadegan Brook Site Reserve Mines Fire Station Fire Station & Fire Hall ‐ Emergency Services infrastructure ‐ Staff noted no known flood risk at this location Unknown Review flood risk and resiliency ‐ Not reviewed in detail Unknown Condition and capacity assessment. Cadegan Brook 1 Kings Road crossing west of Church Unknown Structure Not reviewed Unknown ‐ Not reviewed in detail Unknown Condition and capacity assessment. Cadegan Brook 3 Tributary crossing at Kings Avenue Unknown Structure Not reviewed Unknown Tributary CN trail crossing west of ‐ Not reviewed in detail Unknown Condition and capacity assessment. Cadegan Brook 4 Unknown Structure Not reviewed Unknown Kings Avenue Tributary crossing at end of Tulip ‐ Not reviewed in detail ‐ No infrastructure located in the immediate area of the structure. Coordinate with property owner as required. Cadegan Brook 6 Unknown Structure Not reviewed Unknown Street ‐ Possibly a private crossing. Appears to be access to farmland. Tributary crossing at end of Alexis ‐ Not reviewed in detail ‐ Appears to be located next to buildings Coordinate with property owner as required. Cadegan Brook 7 Unknown Structure Not reviewed Unknown Lane ‐ Possibly privately owned structure. Tributary crossing at Trail west of ‐ Not reviewed in detail Unknown Condition and capacity assessment. Cadegan Brook 8 Unknown Structure Not reviewed Unknown Neville Street Tributary crossing at Trail west of ‐ Not reviewed in detail Unknown Condition and capacity assessment. Cadegan Brook 9 Unknown Structure Not reviewed Unknown Neville Street Phalen Road crossing near Reserve ‐ Not reviewed in detail ‐ Not easily visible. Some uncertainty in routing/condition. Condition and capacity assessment. Cadegan Brook 15 Unknown Structure Not reviewed Unknown Street, south ‐ Appears to cross private property Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 5 of 10 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
Reserve Street crossing near Phalen ‐ Not reviewed in detail ‐ Not easily visible. Some uncertainty in routing/condition. Condition and capacity assessment. Cadegan Brook 16 Unknown Structure Not reviewed Unknown Road ‐ Appears to cross private property Haulage Road crossing near Reserve ‐ Not reviewed in detail Unknown Condition and capacity assessment. Cadegan Brook 17 Unknown Structure Not reviewed Unknown Street Dominion Street crossing near ‐ Not reviewed in detail Unknown Condition and capacity assessment. Cadegan Brook 20 Unknown Structure Not reviewed Unknown McLeod's Road Neville Street Crossing, north of ‐ NSTIR owned Unknown Condition & Capacity Assessment Cadegan Brook 21 Culvert Not reviewed Unknown Holland Street Mine Water Treatment Access Road ‐ ‐ Not reviewed in detail Unknown Condition and capacity assessment. Cadegan Brook 22 Culvert Not reviewed Unknown South Crossing Main Street crossing at Haulage ‐ Not reviewed in detail Unknown Condition and capacity assessment. Cadegan Brook 23 Culvert Not reviewed Unknown Road ‐ Owned by PWGSC ‐ Responsibility of PWGSC Coordinate with PWGSC Underground Mine and Cadegan Brook Site Mine and Treatment Facility Not reviewed ‐ Concerns of I/I from wetland into mine underground workings Unknown Treatment Plant ‐mine water pumped to treatment facility which then has to treat the I/I Cadegan Brook Site Dominion Rink Rink Not reviewed ‐ High frequency of help desk calls near adjacent brook ‐ Not reviewed in detail Unknown Review flood risk
Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 6 of 10 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
‐ Cast‐in‐place concrete box structure within deep road embankment ‐ Identified as a potential high risk, given the structure size in comparison to the Condition & Capacity Assessment ‐ Reportedly passed flows in 2016 event but partially blocked with debris high flow volume and velocities in Renwick Brook. (bleachers) from upstream park ‐ Blockage in a high flow event could result in a significant build‐up of water Rectangular Concrete Culvert Renwick Brook 4 Park Street Crossing ‐ AT Trail proposed next to culvert. Consider public safety. behind the road embankment, which could pose a secondary risk of catastrophic 3 in Road Embankment failure. ‐ Risk to public safety due to high flow depth, velocity and potential risk of catastrophic embankment failure ‐ Identified by staff as a bottleneck in the system, with localized flooding ‐ System bottleneck Investigate culvert routing, perform Condition & Capacity McKeen Street/King Edward Street Renwick Brook 15 Culvert ‐ Adjacent residential sewer back up issues ‐ Risk considers past reports of flooding and uncertain condition of the long culvert 3 Assessment. Plan for upgrade crossing ‐ Long stretch of culvert under roadway and private property under road and private infrastructure. ‐ Not reviewed in detail ‐ Risk level considers unknown condition/routing on underground system Investigate culvert routing, perform Condition & Capacity ‐ Long piped system, crossing Chappel, Rockdale, Hillside, McDonald, and Alexander ‐ Possible limited major drainage route in underground system capacity is Assessment. Plan for upgrade ‐ Long underground culvert system is challenging to assess/maintain condition. exceeded. Piped System Outlet at Alexander ‐ Basement flooding reported in 2016 event Renwick Brook 16 Outlet of Piped System Unknown 3 Street ‐ Residential sewer back up issues ‐ Condition largely unknown. Flagged by staff as possibly undersized and requiring further investigation
‐ High frequency of help desk calls in this area. ‐ Identified by CBRM staff as poor condition, requiring replacement Requires replacement Buried corrugated, poor Renwick Brook 27 York Street crossing Culvert ‐ Long Structure crossing private property 3 condition ‐ Staff have identified need for replacement. Easement is required/pending. ‐ Impacted in 2016. Access was limited to east only. ‐ Possible flooding of emergency services Consider re‐locating comfort centre. Review potential upgrades to ‐ Firehall considered comfort center ‐ Limited access for emergency Services Hickman access to ensure continued emergency services route in Renwick Brook Site Glace Bay Fire Station Fire Station 3 ‐ Emergency route via Hickman Street recently installed flood events. Consider building floodproofing, temporary relocation in flood events. ‐ Staff reported that the Glace Bay commercial area was previously a swamp ‐ Known location of roadway flooding. Emergency flood response planning, including operations response, before development. ‐ Limited access for emergency service emergency re‐routing, traffic diversions, etc. Conduct local watershed ‐ High frequency of help desk calls in this area ‐ Limited access to commercial sites (local economy) detailed flood risk mapping and assessment to identify risk potential. Renwick Brook Site Reserve Street Road/Transportation Route 3 Consider road modifications (raising), improved downstrem stormwater system capacity, and secondary road upgrades to divert traffic and emergency services. ‐ CBRM has indicated the station is to be moved to Brodie Street ‐ Limited access for emergency vehicles Planned relocation Renwick Brook Site Glace Bay Police Station Police Station 3 ‐ Risk level indicates present risk ‐ Located immediately downstream of the control weir structure and spans the full ‐ Risk considers age of structure and importance of the crossing for emergency Condition & Capacity Assessment including Sea‐Level Rise and Storm Renwick Brook 1 Commercial Street Bridge Deck Truss Bridge Aged structure width of Renwick Brook. routing and transportation 2 Surge ‐ Brook is under tidal influence in this area ‐ Located within Brook Ravine, close proximity to water ‐ Risk of being impacted in flood event due to close proximity to the brook Review structure resiliency to possible flooding Renwick Brook 3 Pedestrian Bridge near May Street Pedestrian Bridge ‐ Failure could result in impact to downstream spillway and Commercial Street 2 Bridge ‐ Destroyed in 2016 flood event. Structure was repaired and upgraded. ‐ Known location of past flooding Condition & Capacity Assessment ‐ Ballfield flooded twice, bleachers carried downstream. ‐ Risk level reflects that the infrastructure is likely to flood, but park infrastructure Renwick Brook 5 Cameron Bowl Trail Bridge Multi‐Span Culverts/Bridge Recently repaired 2 ‐ Park is located within known floodplain is less critical to public health and safety than roadway infrastructure
‐ Flagged as poor condition, requires replacement ‐ Identified by CBRM staff as poor condition, requiring replacement Requires replacement ‐ No reported issues in 2016 event ‐ Located at downstream end of system. Failure or capacity restrictions could Renwick Brook 18 Water Street crossing to Outfall Outfall Poor 2 ‐ Lobster boats dock downstream of outfall cause backwater effects upstream. ‐ Siltation concerns identified in 2018 ‐ Not reviewed in detail ‐ Open Channel in residential area Condition and capacity assessment. ‐ Appears to be private infrastructure ‐ Risk considers frequency of help desk call and reported issues Renwick Brook 19 Luke Street crossing Unknown Structure Not reviewed 2 ‐ Adjacent residential sewer back up issues ‐ High frequency of help desk calls in this area Renwick Brook 25 Catherine Street crossing Unknown Structure Not reviewed ‐ Upstream Channel is deep with high velocities ‐ High velocities, risk of debris generation, public safety 2 Condition and capacity assessment. ‐ Adjacent home was flooded in 2016 ‐ Uncertain culvert condition/routing. Appears to traverse private property Condition and capacity assessment. Renwick Brook 30 Highland Street crossing Culvert Unknown 2 ‐ Staff flagged required investigation of culvert ‐ Possible flooding/impacts to adjacent residential homes ‐ Debris blockage in 2016 event ‐ Risks of capacity restriction from future blockages Structure inlet repairs, inlet upgrade to prevent debris buildup., Recently Extended Inlet, ‐ Grate at inlet structure (damaged) ‐ Main outlet of upstream system which is known to flood. Condition and capacity assessment of downstream section of culvert. Renwick Brook 32 Hickman Street crossing Box Culvert 2 Damaged grate ‐ Possible blockage from animal habitat in the area ‐ Risk considers possible upstream impacts if blocked. ‐ Inlet extended to provide emergency access
Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 7 of 10 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
‐ Staff indicated that formwork is being upgraded and possible replacement ‐ Risk considers that staff have flagged poor structure condition and known Condition assessment, consider for replacement/upsizing. Reserve Street crossing between Renwick Brook 34 Box Culvert Not reviewed required. drainage issues in this commercial area. 2 Macfadgen and Gannon Streets ‐ Staff reported that the Glace Bay commercial area was previously a swamp ‐ Commercial Property Flooding Consult with business/commercial property owners to encourage before development. ‐ Impacts to private business building flood protection measures. Consider land use planning and Renwick Brook Site Glace Bay Market Mall Shopping Centre ‐ High frequency of help desk calls in this area 2 policy on storm drainage. Plan for new commercial centre in community master planning. Consider relocation of most at‐risk infrastructure if identified by detailed flood risk assessment. ‐ Staff reported that the Glace Bay commercial area was previously a swamp ‐ Commercial Property Flooding Consult with business/commercial property owners to encourage Renwick Brook Site Bargain Basket Commercial Building before development. ‐ Impacts to private business 2 building flood protection measures. ‐ High frequency of help desk calls in this area ‐ Infrastructure replaced near Park Street ‐ relocated out of brook retaining wall ‐ Sanitary sewer located within known brook floodplain Analysis of sanitary system operations, consider I/I reduction Sanitary System along Renwick ‐ Trunk line crosses the brook on its way to the ocean ‐ High I/I (reported 500 gal/per/day) strategies. Consider relocation/diversion of system where possible. Renwick Brook Site Sanitary System 2 Brook ‐ Capacity issues identified in lower section ‐ Risk of SSO to environment ‐ Known cross connections Roadway/Transportation ‐ Combined sewer separation completed ‐ Staff identified a need for culvert condition assessment Planned condition & Capacity Assessment Renwick Brook Site Currie Street 2 Route ‐ Culvert condition study planned for the area ‐ Risk of structure failure and impacts to roadway ‐ Reportedly not overtopped by tides in 2016 event ‐ Coastal risk Sea‐Level Rise and Storm Surge Review ‐ Staff reported that tide has not been known to reach the top of the spillway Renwick Brook 2 Renwick Brook Spillway Spillway Constructed in 1983 ‐ Originally Installed in 1983 1 ‐ Assessment done in 2017.
‐ NSTIR owned ‐ Risk considers that the structure is newer in age than others on the main system Condition & Capacity Assessment Renwick Brook 7 Dominion Street crossing Pre‐cast Concrete Bridge Upgraded in 1990s ‐ Replaced approximately 25 years ago and is located further upstream. 1 ‐ Important transportation route and emergency access. ‐ Not reviewed in detail Unknown Regular Maintenance Program Renwick Brook 14 Minto Street crossing Unknown Structure Not reviewed ‐ Previously overgrown channel, recently cleaned out with minor improvement 1 noticed Renwick Brook 17 Chappel Drive Culvert Culvert Repaired in 2018 ‐ Collapsed in June 2018 ‐ Risk level considers recent replacement 1 Repaired in 2018 ‐ Collapsed in 2016 and replaced ‐ Risk considers recent upgrade of the structure. Recently upgraded Renwick Brook 21 Quarry Street crossing Culvert Replaced 2016 ‐ Re‐ditching completed since 2016 1 ‐ High frequency of help desk calls in this area ‐ Not reviewed in detail Unknown Condition and capacity assessment. Renwick Brook 28 Union Street crossing Culvert Not reviewed 1 ‐ Considered by staff to be less of a risk than others on the system ‐ Larger culvert diameter compared to others on the system ‐ Uncertainty in culvert condition Condition and capacity assessment. Renwick Brook 31 Rosewood Avenue crossing Corrugated Steel Culvert Not reviewed 1 ‐ Identified as perched culvert, higher than rest of the channel ‐ Risk considers that Culvert will be removed Planned culvert removal and channel daylighting Renwick Brook 33 Access road crossing Culvert ‐ CBRM working with businesses to remove culvert 1
‐ School appears to be situated on higher ground, but concerns over access ‐ Limited access Review flood resiliency and risk. Plan for alternate access routes in Renwick Brook Site Glace Bay High School School 1 flood event. Public communication and outreach. Roadway/Transportation ‐ Main Street is the alternative emergency route for when Reserve and Dominion ‐ Important alternative emergency route Review flood risk and resiliency Renwick Brook Site Main Street 1 Route are down. ‐ Not reviewed in detail ‐ Does not appear to be in close proximity to other infrastructure. Condition/flood resiliency assessment. Pedestrian crossing north of Renwick Brook 6 Pedestrian Bridge Not reviewed ‐ Consider risk of debris impacts downstream if structure were to fail in flood Unknown Dominion Street event. ‐ Not reviewed in detail ‐ Does not appear to be in close proximity to building infrastructure, however Coordinate review for environmental risks. Renwick Brook 8 Emery Street crossing Unknown Structure Not reviewed ‐ Appears to be private access possible agricultural water treatment nearby which could be an environmental Unknown risk. ‐ Not reviewed in detail Unknown Condition and capacity assessment. Trail crossing between Steeles Hill Renwick Brook 9 Unknown Structure Not reviewed Unknown Road and Sharpes Lane
Renwick Brook 10 Outlet West of Bell Street Outfall Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Renwick Brook 11 Bell Street crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Renwick Brook 12 Main Street crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Renwick Brook 13 William Street crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Renwick Brook 20 South Street crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Renwick Brook 22 Macaulay Avenue crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Renwick Brook 23 Dawe Avenue crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Renwick Brook 24 Dinn Avenue crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Renwick Brook 26 Upper Mclean Street crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. Between Highland Street and Union ‐ Not reviewed in detail Unknown Condition and capacity assessment. Renwick Brook 29 Open Channel Not reviewed Unknown Street Trail crossing between Ling Street ‐ Not reviewed in detail ‐ Does not appear to be in close proximity to other infrastructure. Condition and capacity assessment. Renwick Brook 35 Unknown Structure Not reviewed Unknown and Reserve Street Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 8 of 10 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
‐ Not reviewed in detail Unknown Condition and capacity assessment. Access road crossing to Glace Bay Renwick Brook 36 Unknown Structure Not reviewed ‐ Likely a privately owned structure. Unknown Market Mall ‐ Secondary mall access Reserve Street crossing east of ‐ Not reviewed in detail Unknown Condition and capacity assessment. Renwick Brook 37 Unknown Structure Not reviewed Unknown Sobeys Reserve Street at Glace Bay ‐ Reported flooding of street and commercial areas Unknown Condition and capacity assessment. Renwick Brook 38 Road/Transportation Route Not reviewed Unknown Commercial Area ‐ Not reviewed in detail ‐ Consider access to High School Condition and capacity assessment. Reserve Street crossing near Glace Renwick Brook 39 Unknown Structure Not reviewed Unknown Bay High School Access Road Trail crossing north of Dominion ‐ Not reviewed in detail Unknown Condition and capacity assessment. Renwick Brook 40 Unknown Structure Not reviewed Unknown Street Rail crossing north of Dominion ‐ Not reviewed in detail Unknown Condition and capacity assessment. Renwick Brook 41 Unknown Structure Not reviewed Unknown Street Highland Street crossing near ‐ Not reviewed in detail Unknown Condition and capacity assessment. Renwick Brook 42 Unknown Structure Not reviewed Unknown Greenwood Cemetery ‐ Not reviewed in detail Unknown Condition and capacity assessment. Access Trail crossing between Reid Renwick Brook 43 Unknown Structure Not reviewed Unknown Avenue and Lorway Street
Renwick Brook 44 Steeles Hill Road crossing Unknown Structure Not reviewed ‐ Not reviewed in detail Unknown Unknown Condition and capacity assessment. ‐ Fish Plant ‐ Identified by staff as potential tidal risk Coastal risk assessment considering tides, storm surge and sea level Renwick Brook Site Fish Plant Fish Plant Unknown ‐ Risk rating not assigned ‐ coastal risk rise. ‐ Not considered comfort center ‐ Staff flagged as minimal risk Review flood risk and resiliency Renwick Brook Site Bayplex Sports complex Unknown ‐ Not reviewed in detail Unknown Unknown Renwick Brook Site Storm outfall Outfall ‐ Storm system outfall Unknown ‐ Was previously covered in stone, exposed in 2016 Proposed Treatment Plant ‐ Site of proposed treatment facility ‐ Future Proposed future site must consider flood risk planning. Renwick Brook Site Proposed Glace Bay Treatment Plant Future Site
Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 9 of 10 181‐03080 CBRM Flood Risk Assessment ‐ Inventory Table WSP Canada Inc.
Structure Watershed Location Description Structure Description Condition Flags Workshop Notes & Historical Background Risk Description Risk Rating Possible Mitigation Strategy Number
‐ Replaced prior to 2011 ‐ Known area of flooding at Pierce Street Review Condition & Capacity Assessment ‐ Located just upstream of Smelt Brook Park ‐ Structure risk requires confirmation of structure influence on/susceptibility to Smelt Brook 2 Pierce Street Box Culverts Twin Box Culverts Recently replaced ‐ Reported past flooding along Pierce Street, adjacent Fire Hall flooding. 3 ‐ In 2010, police set up barricades to close Pierce Street. One car passed, resulting ‐ Flooding of Pierce Street has secondary risk/impacts on access to adjacent Fire in engine damage. Hall and Fire Station. ‐ CN Rail line is no longer in use ‐ Since rail line is abandoned, risk of limited structure maintenance. Confirm responsibility over structure, perform condition and capacity Abandoned structure, ‐ Uncertainty over maintenance responsibility. ‐ While structure capacity appears to be greater than others along the systems, assessment and develop maintenance/ replacement/ demolition Smelt Brook 4 Rail crossing near Clifford Street Arch culvert 3 signs of bank erosion. the rail Line is significantly higher than adjacent ground and could act as a dam in plan. the event of structure failure. ‐ Reported flooding of road and gravel parking lot in 2016 event. ‐ Located within possible flood zone Requires consultation with Emergency Services to develop interim ‐ High help desk call frequency in the area ‐ Impeded emergency access in flood event, risk of affecting emergency response. flood risk management plan. Consider secondary access routes, ‐ Access to the building impeded due to flooding ‐ Fueling infrastructure located within flood zone‐ risk of environmental and public temporary relocation of trucks and services, additional protections to Smelt Brook Site Fire Station Fire Station & Fueling Station ‐ Underground fuel storage tanks and fueling station on site. safety. 3 building and fuel station. Relocation may be required, depending on ‐ Limited space, CBRM considering expansion ‐ Lack of fuel supply for vehicles during flood event. further detailed flood risk analysis. ‐CBRM considering installing backup generator ‐ Limited direction in for emergency vehicle travel ‐ Reported flooding of road and gravel parking lot in 2016 event. ‐ Located within possible flood zone Consider another location for proposed comfort centre. Review ‐ High help desk call frequency in the area ‐ Impeded access to fire hall in flood event, which negates function as an possible flood protection measures in relation to floodplain. Consider Smelt Brook Site Fire Hall Fire Hall 3 ‐ Access to the building impeded due to flooding emergency comfort centre. building floodproofing or relocation. ‐ CBRM is considering as a proposed comfort station for emergency events ‐ Storm surge, sea‐level rise ‐ could impact structure, as well as produce backwater Plan for structure condition assessment and required upgrades. Failing walls and Smelt Brook Outlet Channel to Concrete/Wooden Outlet ‐ Downstream channel influenced by Harbour Tides. effect with further impacts at upstream Smelt Brook park. Capacity Assessment including Sea‐Level Rise and Storm Surge. Smelt Brook Site deterioration along 3 Harbour Channel ‐ Risk of collapse of deteriorated walls along outlet channel, could restrict outflow outlet channel. from Smelt Brook to the Harbour and result in upstream impacts. ‐ Queen Street Bridge reportedly not flooded. ‐ Storm surge, sea‐level rise ‐ could impact structure, as well as produce backwater Condition & Capacity Assessment including Sea‐Level Rise and Storm ‐ Downstream channel influenced by Harbour Tides. effect with further impacts at upstream Smelt Brook park. Surge Queen Street Bridge& Harbour Smelt Brook 1 Pre‐cast Concrete Bridge ‐ Risk of collapse of deteriorated walls along downstream outlet channel, which 2 Outlet could restrict outflow from Smelt Brook Park to the Harbour and result in flooding of Queen Street. ‐ Operations staff did not report structure/road flooding ‐ Aged infrastructure should be assessed given past failure of other structures on Condition & Capacity Assessment ‐ Adjacent low‐lying residential properties have experienced flooding the same system. Smelt Brook 5 Wilkie Drive Crossing Concrete Bridge/Box Culvert Aged structure ‐ Upstream brook is densely vegetated. ‐ Low topography, possible risk to residential properties in close proximity to 2 brook system. ‐ Debris from upstream vegetation in high flow event. ‐ Operated by CBRM staff ‐ No flags raised by staff on current condition. Condition assessment and failure risk assessment. Consider increased ‐ Controls outflow from Pottle Lake System ‐ Risk should be assessed, as failure could result in release of stored water, storage opportunities for flood mitigation. Smelt Brook 7 Pottle Lake Reservoir Control Weir Twin Control Weir Structure 2 ‐ Consider opportunities for potential upgrade to retain water upstream in a heavy resulting in high flow velocities and potentially catastrophic impacts downstream. rainfall event. ‐ Replaced 2017 ‐ Recent replacement, no reports of recent flooding. Monitor performance of new structure. Smelt Brook 3 Regent Street Bridge Pre‐cast Concrete Bridge Recently replaced ‐ Armour rock placed on adjacent banks ‐ Residential homes in close proximity to brook and potential flood area 1 ‐ Nearby residential homes on Local street in low area ‐ Downstream channel is heavily vegetated ‐ Since control weir is located immediately upstream, flow and associated level of Condition and capacity assessment. Smelt Brook 6 Musgrave Lane Box Culvert Concrete Box Culvert ‐ Adjacent outlet from treatment facility is primarily associated with the weir structure. 1 ‐ Lake control weir located immediately upstream ‐ Existing pump station/treatment facility near Pottle Lake weir. ‐ Environmental risk Consider capacity and outfall threshold Pump Station/Treatment near Pump Station/ Treatment Smelt Brook Site ‐ No past flooding reported ‐ No past flooding reported 1 Pottle Lake Weir Facility ‐ Discharge to Smelt Brook ‐ Known area of flooding ‐ Known flooding of park in heavy rainfall events. Flood resiliency assessment and public communication regarding Smelt Brook Site Smelt Brook Park Park 1 ‐ Downstream tidal influence expected park flooding during heavy rainfall/tidal events. ‐ Not reviewed in detail Unknown Condition and capacity assessment. Pottle Lake Outlet & Highway ‐ System is controlled by downstream weir on east side of the highway Smelt Brook 8 Not Reviewed Not Reviewed Unknown Crossing ‐ Stop logs at lake outlet ‐ Fish passage is a consideration ‐ Staff flagged Tidal submergence 2010 ‐ Coastal (Tides, Storm Surge, Sea‐Level Rise) Consider condition assessment and risk from tides, storm surge and Smelt Brook Site Wharf South of Commercial Street Wharf Unknown ‐ Risk not rated since structure lies outside the watershed under review. sea‐level risk.
Note: Inventory based on varying levels of available info at time of study (e.g. site visits, stakeholder workhops, consultations, desktop review). Subject to change following further analysis. Draft Final ‐ Printed 3/11/2019 Page 10 of 10 ClimAction Services
ClimAction Services Inc.
Climate Observations and Projections In Support of Flood Risk Assessment for Cape Breton Regional Municipality
ClimAction Services Inc. November 2018 (Updated March 2019)
[email protected] ClimAction Services Inc.
ADDENDUM CBRM Final Report - June 2019
Background
In the fall of 2018, the Cape Breton Regional Municipality (CBRM) contracted the engineering firm, WSP Canada Inc., to aid in producing a flood risk analysis for the National Disaster Mitigation Program (NDMP) funding submission. WSP sub- contracted ClimAction Services Inc. to assist in that analysis and provide climate change information including projected extreme rainfall amounts.
The Final Report section generated by ClimAction Services Inc. was based on various databases and climate model tools including the Intensity, Duration, Frequency (IDF) curves for extreme precipitation available from Environment Canada Climate Change (ECCC). The IDF curves were based on annual maximum rainfall amount data collected from 1961-2009. The Final report also provided a complete forensic analysis of past storms and flooding scenarios including the significant rainfall event that occurred in Oct 2016.
The Report which was submitted to CBRM in March 2019 included a complete flood risk analysis based on ClimAction Services’ climate change projections for the area. The Report contained a list of recommendations and conclusions that CBRM could use for future development of design storms to mitigate potential flooding hazard.
In February 2019, ECCC issued an updated (national) suite of IDF curves based on data from 1961 to 2016. The updated IDF curve relevant to CBRM (Sydney CS) included the Oct 2016 rainfall event and changed the values for every period and intensity. Due to this change, the updated IDF is now the recommended rainfall information suite when analyzing historical extreme rainfall events.
This update can be accessed through ECCC’s Historical Climate Data web link: ftp://ftp.tor.ec.gc.ca/Pub/Engineering_Climate_Dataset/IDF/
Due to this update, this Addendum has been added to the Report to provide additional recommendations. Current recommendations in the Final report are still valid.
Added Recommendations
1. All readers and users of the Report’s findings should access the latest data related to rainfall and flooding in CBRM, including the latest IDF curves generated by ECCC. 2. All users of the data should be aware that ECCC has produced updated IDF curves that include the Oct 2016 event and that can be used in assessing extreme rainfall events, developing design storms and assessing flooding for the purpose of mitigating potential flooding events. 3. For all readers and users of the Final Report, it continues to be recommended that the information available from the Oct 2016 storm be utilized in any design storm development as it has already impacted CBRM and provides real- time data for a potential design storm. This information includes valuable historical reference to the short duration rainfall potential (i.e. rainfall amounts over 1-2hour periods). Climate Observations and Projections in Support of Flood Risk Assessment for Cape Breton Regional Municipality.
Author: ClimAction Services Inc., Halifax NS
Prepared for: Cape Breton Regional Municipality, September 2018.
Acknowledgements: The author wishes to acknowledge the following individuals for their assistance in developing this climate change information:
Rick Fleetwood in Fredericton, NB and Bridget Thomas in Dartmouth NS. Climate Services, Atlantic Region, Environment and Climate Change Canada.
Eva Mekis and Lucie Vincent, Ontario Region, Environment Canada.
Neil Comer, Climate Scientist, Risk Sciences International, Toronto, Ont.
Disclaimer: This publication is not to be used without permission and any unauthorized use is strictly prohibited. The author(s) and the Cape Breton Regional Municipality are not responsible for any unauthorized use that may be made of the information contained herein. The opinions expressed in this publication do not necessarily reflect those of the Cape Breton Regional Municipality. Citation: ClimAction Services Inc., 2018. Climate Observations and Projections in Support of Flood Risk Assessment for Cape Breton Regional Municipality. ClimAction Services Inc. (Halifax) under contract. November 2018. Photo Credits: Page1: Brookland Elementary School October 2016. Brett Ruskin, CBC. Page 4: Image of Corner of Whitney Avenue and Hospital Street, October
2016. Lachlan MacKinnon.
November 2018 (Updated March 2019) 2
Table of Contents
Page No.
1. Introduction 4 2. Background 5 3. Flood Scenario Definitions 7 4. Data - Sources and Analysis 8 5. Forensic Analysis 14 6. Climate Baseline and Projections 17 7. Sea Level Rise and High Water 21 8. Summary of Results 22 9. References 23 10. List of Figures 24 11. List of Tables 25 12. Appendix A. – List of Observing Sites CBRM – Map 26 13. Appendix B. – Global Climate Model Procedures 28 14. Appendix C. – List of Climate Models 30 15. Appendix D. - Graphical Representation of IDF Curve for Sydney CS. 32 16. Appendix E. – Chart Datum vs CGVD28 33
November 2018 (Updated March 2019) 3 1. Introduction
The National Disaster Mitigation Program (NDMP) was introduced to allow various jurisdictions who have infrastructure and public safety at risk from climate events to apply for funding to help mitigate that risk. The funding request process includes identifying risk by completing a risk analysis template developed by NDMP.
The Cape Breton Regional Municipality (CBRM) has experienced infrastructure loss and threats to public safety from flooding events driven by extreme climate, especially extreme precipitation events. At present the CBRM recognizes that, to best satisfy the NDMP funding criteria, it must, once again revisit these extreme climate events and describe the consequences in the format of a risk analysis.
To best complete that task, CBRM has contracted the engineering firm, WSP Canada Inc. Global, to produce a completed risk analysis based on the NDMP’s criteria. WSP has sub-contracted ClimAction Services Inc. to assist in that analysis as well as provide climate change information including projected extreme rainfall amounts.
The following information is to be used as background for that risk assessment and exists as a current reference document related to historical and projected climate events, focusing on extreme precipitation.
Access to more information on the NDMP can be acquired at this government website: https://www.publicsafety.gc.ca/cnt/mrgnc-mngmnt/dsstr-prvntn-mtgtn/ndmp/index-en.aspx
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2.0 Background
Since the 1950s there has been an increasing trend in extreme climate events across the globe (IPCC, 2012.). These events vary in type and frequency by region, for example, some regions receiving more intense rainfall while others experience hotter days and extended drought. As well, these events vary by season, with heavy rainfall shifting to impact agricultural yield (as one example), both positively and negatively. Evidence and research indicate that these events will continue to increase in frequency and intensity as climate changes over the next century.
On a global scale, one of the more devastating events has been flooding due to heavy rainfall. Recent events in major urban areas of Canada include the Calgary floods (2005 & 2013), Toronto flooding (2018) and recent inundation in Sydney NS.
Risks to infrastructure and public safety from extreme climate events have been of concern to many groups and organizations over the past 20 years. Most recently Engineers Canada has been concentrating on developing procedures and protocols to best adapt their design practices to accommodate climate change and the increasing threat of extreme weather.
The Federal Government, under the auspices of Public Safety Canada and Infrastructure Canada, have begun concentrating on extreme climate events as they impact public safety and infrastructure resilience.
As an aid to mitigating the impacts of such severe events, the Federal Government has provided funding through the National Disaster Mitigation Program (NDMP). However, to access NDMP funding, jurisdictions must complete and submit a risk assessment, identifying specific events that have created significant safety issues and the most vulnerable locations in that jurisdiction.
To that end, the Cape Breton Regional Municipality (CBRM) has identified, from a study of impacts of past severe events, five specific watercourses that are prone to flooding and, by flooding, pose significant risk to public safety and infrastructure in CBRM. Report Scope
This report will focus on historical, current and future precipitation events that have and will impact flood prone areas in CBRM. In order to keep the scope of the project within a reasonable capacity, the project limits its coverage to five specific watercourses and their surrounding areas as noted in Table 1.
Name of Watercourse Location Reservoir Brook/Wentworth Creek Sydney Prime Brook Sydney Renwick Brook Glace Bay Cadegan Brook Dominion Smelt Brook North Sydney
Table 1. Locations of five watercourses of concern in CBRM.
These watercourses have qualified for risk assessment under NDMP based on historic and recent flooding events. A map of the five watercourses and their location in CBRM is available in Appendix A.
November 2018 (Updated March 2019) 5 This report will also engage in an examination of existing observational data of precipitation, analysis of that data and generation of climate change projections for the CBRM watercourse areas. By doing so, information will be provided to aid in the risk assessment process.
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3.0 Flood Scenario Definitions
This report, and the project, will focus specifically on “pluvial” flooding across 5 specific watercourse areas of CBRM.
“Pluvial” Flooding is defined as a “surface water flood, caused when heavy rainfall creates a flood event independent of an overflowing water body… it can happen in any urban area — even higher elevation areas that lie above coastal and river floodplains.” (Excerpt from INTERMAP website: http://www.intermap.com/risks-of-hazard-blog/three- common-types-of-flood-explained )
For the purposes of this report’s work, such “pluvial” flooding can be described based on the following specific meteorological events combined with landscape condition and may occur during specific seasons in CBRM.
The overall climate of the Cape Breton region is influenced by its proximity to the Atlantic Ocean as well as its location approximately half-way between the North Pole and the Equator. This places it on a storm track that includes intense Nor’easters as well as tropical cyclones.
Heavy Rainfall – Most heavy rainfall (>50mm in 24 hours) is produced by intense Nor’easters or tropical cyclones. Both types of storms occur most frequently during the late summer, autumn and occasionally during the winter months. Related to these events during the winter is rainfall occurring on snow cover, creating a significant melt scenario that can turn into an enhanced flooding scenario.
Multi-day Accumulation – Rainfall that persists and accumulates over several days is typically related to slow-moving or stalled storms. Meteorologically these occur during a period where the west-to-east progression of storms is “blocked” by upper atmospheric features, prolonging their existence over the region. Flooding from such storms can be intensified when persistent rainfall occurs during a thaw and creates run-off along frozen ground.
Flash Flood – High intensity, short duration rainfall can be related to intense meteorological events such as convective cells (thunderstorms) occurring as isolated “summer” thunderstorms or embedded in large-scale storms. Such rainfall is usually intensified by dramatic slope in river valleys.
Coastal high water – storm surge – Coastal flooding can occur and worsen inland flooding when significant storm events combine with high tide, creating storm surge at the coast or mouth of rivers. These events can occur with intense Nor’easters, especially in the autumn.
These scenarios have occurred in CBRM in the past and are projected to occur more frequently and intensely in the future with climate change.
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4.0 Data – Sources and Analysis
4A. Sources of Data
To properly describe the climate of a region, historical information based on a number of climate parameters must be analyzed. Creating this analysis is commonly referred to as identifying a “climate baseline” for that region.
Historical climate data for the Cape Breton Regional Municipality (CBRM) exists at several sites but at a wide variety of time periods and varying quality. To best create the “climate baseline” for this area, suites of observed data must meet duration and quality standards. Such standards include length of record, quality of record (human observer or automated site) and amount of missing data. These standards will limit the number of observational data sets that can be used, and especially if the focus is on precipitation amount and type on a daily to monthly time scale.
Primary Sources
To examine sites that can provide such information, several archive databases are available online. The first one is the National Data Archive at Environment Canada Climate Change (ECCC). Most of the information can be accessed through Climate Data Online and available in CSV or spreadsheet format to accommodate further analysis. Most of the sites available have had a basic level of quality control but some data may be flagged to indicate potential problems.
Another important access point is ECCC’s Adjusted Historical Canadian Climate Data. Here the data has been adjusted (in some cases 2 or 3 sites have been combined) to correct for non-weather changes in the observed data such as change of instrument position, change of observing type (human to automatic), etc. This database is utilized when trends in long data sets are required. For this project such trend analysis is not required.
Secondary Sources
Two volunteer networks provide daily and monthly observations from citizen observers.
CoCoRaHS (Community Collaborative Rain Hail and Snow) network has continually produced precipitation amount observations over the past 10-15 years. Although the reports are only of precipitation amount, the location of the observing sites can provide valuable information in spots where no Environment Canada sites exist.
The Cape Breton Weather Network is also a volunteer observing network that provides daily and monthly observations of temperature, precipitation and visibility.
To choose sites that could clearly represent the climate across CBRM, an examination of the available data per site (see Table in Appendix A) as well as the time period and quality was performed. One such examination results in the current record precipitation values prior to 2016, as noted in Table 2.
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Site Number Site Name Maximum 24hr Rainfall (mm) 8205702 Sydney CS 134.8 (1981) 8205703 Sydney Airport 128.8 (1981)
8203163 Louisbourg 105.0 (1981) 112.8 (2000) 8203422 Margaree Forks 114.8 (1971) 8202502 Ingonish Beach 143.8 (1970) 8200300 Baddeck 115.0 (1977)
Table 2. Maximum 24hr Rainfall Records prior to 2016.
4B. Analysis of Data
Examination of the importance of the data record requires several levels of analysis. These levels start with the basic creation of average values, such as average precipitation amounts by month, season and year. While such values provide sufficient information to be useful as a “climate baseline”, they provide only a superficial understanding of the character of precipitation at any given location.
Of more use are analyses that provide information of the character of precipitation, mainly how has precipitation occurred across the geographical scale, i.e. more regionally than locally, and how has the precipitation occurred across more specific time scales, including intensity and duration for specific amounts. Both analyses can provide more insight into the nature of precipitation historically. What follows illustrates these analyses approaches. 4B1. CANGRID Database
To account for data sparse areas, most typically across heavy forested reaches as well as mountainous areas, Natural Resources Canada (NRCan) through their Forestry Service, developed a national gridded observational data base called CANGRID. To aid in understanding the impact of climate on Canadian forests, specialized mapping techniques were developed by McKenney and Hutchison in 2001. Part of this technique produces climate observations on a grid that covers most of Canada (including Nova Scotia) in a 10 km scale (see Figure 1) based on available surrounding observational data. A suite of climate observations can then be extracted for a particular site or sites based on a location at or near a grid point, articulated as a latitude/longitude value.
Since the Sydney area of Cape Breton has very limited observation sites (as noted in section 4A), CANGRID grid points equivalent to the 5 watercourse locations were extracted using the Risk Sciences International (RSI) Climate Change Hazard Information Portal (CCHIP) user interface (see section 6C). The results are 3 grid point locations as noted in Table 3. At these points, precipitation information has been extracted through CCHIP so that a more complete climate “baseline” can be created. Each grid point acts as a proxy for the geographical site.
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Figure 1. Example of Grid-boxes over Cape Breton used for CANGRID. Provided by Neil Comer, RSI, Toronto.
CANGRID Sites in CBRM Proxy for Lat/Long grid point (from CANGRID) Sydney Site 1 & 2 46.125 / 60.208 Glace Bay Site 3 & 4 46.208 / 59.958 North Sydney Site 5 46.208 / 60.291
Table 3. CANGRID Proxy Sites for CBRM
Such values are useful to gain some sense of how precipitation may vary across the region on a broad, average time scale (i.e. monthly, seasonally, etc.). However further analysis of specific precipitation events can be more useful to identify extremes and their impact. 4B2. Regional Analysis of Precipitation
As noted in the previous section, CANGRID values are generated statistically based on algorithms that calculate a spacial distribution that is then expressed across a grid. There are other approaches that provide a similar spacial understanding of how precipitation during a specific event is distributed. One such approach is combining observed precipitation from observing sites and radar sensing with weather model output that “fills in the blanks” and generates a “re-analysis” of how that event’s precipitation was distributed across the region.
Such an approach is the “Regional Deterministic Precipitation Analysis” (RDPA) as described by an excerpt from the ECCC website: https://open.canada.ca/data/en/dataset/fdd3446a-dc20-5bad-9755-0855e3ec9b19
“The Regional Deterministic Precipitation Analysis (RDPA) produces a best estimate of the amount of precipitation that occurred over recent past periods of 6 or 24 hours. The estimate integrates data from in situ precipitation gauge measurements, weather radar and numerical weather prediction models. Geographic coverage is North America (Canada, United States and Mexico). Data is available at horizontal resolution of 10 km. Data is only available for the surface level.”
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Figure 2. Radar Return Composite (RDPA) for CBRM Oct 11 2016, Environment Canada.
Such analysis allows determination of where areas of highest precipitation occurred for that time period. In the case of CBRM, (as shown in Figure 2) maximum amounts in excess of 225mm were concentrated over the Mira area while values greater than 175mm spanned the Sydney and Glace Bay area.
There are other methods that focus on extreme event values. 4B3. Extreme Precipitation Analysis - IDF Curves
In 2012, the Canadian Standards Association in collaboration with Environment Canada developed a set of standards involving the definition and use of Intensity, Duration and Frequency (IDF) Curves, both historical and projected, in any engineering endeavor, including water management infrastructure design. This document (CSA Technical Guide, PLUS4013-12) provides background explanation of the current techniques in developing IDF curves, as well as, description of best practices when applying these curves in a climate change scenario.
According to ECCC’s current support documentation, Creation and updating of IDF Curves:
“ECCC provides short-duration rainfall intensity statistics often used for sizing and design of hydrological structures to structurally accommodate and carry water runoff from small catchments… Commonly known as “IDF curves”, the most recent set of IDF tables and graphs for 565 locations across Canada are available in electronic file format…
An IDF curve or graph is produced from an extreme value statistical analysis of at least 10 years of rate-of-rainfall observations. It includes the frequency of extreme rainfall rates and amounts corresponding to the following durations: 5, 10, 15, 30 and 60 minutes, and 2, 6, 12, and 24 hours. Return periods are used as the measure of frequency of occurrence and are expressed in years. Estimates of the rates and amounts for the durations noted above and their confidence intervals for the rates are provided for return periods of 2, 5, 10, 25, 50 and 100 years.”
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“Most of the IDF curves comprise the analysis of rate-of-rainfall observations from tipping bucket rain gauges (TBRGs). Most of the TBRG chart recorders are equipped with daily charts. For these, the shortest duration is 5 minutes. Some TBRG charts are equipped with weekly, not daily charts. For these locations, the shortest duration rainfall is one hour. The annual maximum observation for each duration is compiled for each year. As each new year’s maxima are added for the IDF analysis, basic checks are applied, in addition to the quality control checks at the time the data is archived. This is to ensure that the values selected are the maxima for the year. This involves mainly assessing the completeness of the TBRG observations, and checking, for instance, that larger rainfall amounts didn’t occur during times of the year when the TBRG was not in operation.”
As described earlier, precipitation events can occur as short duration/high intensity events leading to flash flooding or prolonged heavy events that, through accumulation of water, create flooding. Sites with available TBRG data allow for the analysis of short duration (5 minutes and up) events while other sites with daily values can be used to generate longer duration (1, 2 or 3 day) analysis.
Return 5min 30min 1hr 2hr 6hr 12hr 24hr period (yrs) 2 5.3 13.7 18.8 26.6 44.8 56.2 67.6
5 6.8 18.5 26.3 35.9 57.4 69.8 82.5 10 7.8 21.7 31.2 42.0 65.7 78.8 92.3 25 9.1 25.8 37.5 49.8 76.3 90.2 104.8 50 10.1 28.8 42.1 55.6 84.1 98.7 114.0
100 11.0 31.8 46.7 61.3 91.8 107.1 123.2
Table 4. Sydney CS IDF Table Rainfall in mm (based on 2014 data). Courtesy ECCC.
4B4. Atlantic Canada Extreme Precipitation Analysis
To better understand the potential spacial scale of extreme precipitation, a project was undertaken in 2016 that partnered the Northeast Regional Climate Center at Cornell University and the Atlantic Region of ECCC in an effort to provide a regional analysis of extreme precipitation events. The approach was to utilize current knowledge of intensity, frequency and duration (IDF) of extreme events and provide contoured maps of the values across Atlantic Canada and portions of New England.
Such mapping is available at: http://atlantic-canada-precip.eas.cornell.edu/
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The results are maps of historical extreme precipitation events scaled from 5-minute duration to 100year frequency.
Figure 3. Extreme Precipitation Estimates: 24-hr 100-yr Event
Such values are illustrated in Figure 3. For the CBRM it shows values of 24-hr 100-yr events of 130-140mm. 4B5. Summary of Data and Analysis.
From the suites of observational data and four versions of analysis of that data in Section 4b1-4, an understanding of how the basic amounts (monthly, seasonal, annual), extreme amounts and their geographical distribution describe the nature of precipitation events over Cape Breton, and specifically in CBRM.
Here is a summary of those characteristics:
1. Average annual precipitation for the CBRM ranges from 1460-1480mm. current precipitation values as they pertain to monthly seasonal and extreme events in CBRM. For the Fall season amounts average around 410mm (with this mostly as rain although some small snowfall amounts occur in October/November). 2. Extreme rainfall events can range from highly localized convective (thunderstorm) events to large-scale events that affect the entire island. By examining the larger events using regional analysis it can be seen that specific events, such as the October 2016 heavy rainfall, are distributed across the island. 3. Extreme values analysis approaches (such as EVA for building IDF curves) can provide information on the frequency of high intensity, rare events. However such curves are based on historical information, are site specific and may be under-valuing the potential intensity of future events. 4. Mapping the IDF values across the region can create a geographical sense of how these extreme events are distributed.
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5.0 Forensic Analysis
5A. Historical Events
One way of examining precipitation events is to identify significant events (large amounts over short duration, for example) and determine their cause(s) by utilizing the observed historical data available. By determining the cause(s) we may be able to develop future scenarios based on that very case.
For CBRM there have been several significant events over the period of record (last 50 years) but of most significance has to be the October 9-11 2016 rainfall event (Thanksgiving Day storm) (see Figure 5.) In comparison the rainfall event of Aug 17, 1981 generated more intense short duration rainfall (1hr-2hr) but, due to its less intense longer duration values only totaled 134mm of rain over 24hrs. The Oct 2016 event generated less intense short-duration rainfall (10-20mm per hr) but these amounts occurred over a 24hr period totaling near 230mm at Sydney. (See Table 5.)
While the 1981 event informed the latest IDF curves (2014) (see Section 4B2), the October 2016 event has been chosen as the most extreme case due to its nature (as will be demonstrated below) and should be used to construct design storm values or, at least, determine potential impacts from 24hr rainfall exceeding 200m.
In order to understand the impacts of the October 2016 event, a review of its origins and how it differed from other historical extreme events will provide a basis for how to prepare for the repeat of this type of storm; or determine appropriate adaptation measures for similar storms of increased intensity and frequency in the future.
5A1. Background.
The October 2016 Storm began as a tropical cyclone and developed into an extra-tropical storm by the time it tracked over Nova Scotia. The following excerpt was produced by Impact Forecasting as a summary of the storm’s effect from its beginnings until it tracked across Atlantic Canada.
“…portions of Atlantic Canada were lashed by a low pressure area, fueled by the remnant tropical moisture of Hurricane Matthew, which brought significant heavy rainfall to parts of Prince Edward Island, Nova Scotia, and Newfoundland from October 9-11.
…. locations reported rates of 10-20 millimeters (0.4-0.8 inches) per hour which are … considered to be very high… States of emergency were declared in Sydney, NS… (However) there were no reports of any fatalities as a result of the stormy conditions in Canada.
Among the worst affected communities were Sydney, on Cape Breton Island, NS, and Burgeo, on the southern edge of the Island of Newfoundland, where high wind gusts and flooding caused severe and widespread damage. Brookland Elementary School in Sydney was among the numerous buildings in the town to sustain extensive damage. As of November 10, the school remained closed and more than 300 students were being accommodated at other nearby schools. Nova Scotia Power reported that as many as 144,000 customers were without power on October 11 as powerful wind gusts toppled trees and power lines…. Additionally, local authorities reported that thousands of homes across Cape Breton Island suffered inundated basements and ground floors while there were numerous reports in local media of submerged vehicles and roads. Dozens of roads were closed due to flooding and washouts.
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Local officials in Cape Breton Island reported that damage was likely to be well in the 10s of millions (CAD). The repair bill for damage to roads in Newfoundland alone was expected to top CAD1.5 million (USD1.1 million).
Loss estimates from the Canadian insurance industry show that more than 5,000 claims were filed in New Brunswick, Prince Edward Island, Newfoundland, and Nova Scotia pertaining to damage incurred as the result of remnants from Hurricane Matthew. A published report by Catastrophe Indices and Quantification Inc. (CatIQ) cited claims payouts of roughly CAD110 million (USD80 million). The majority of this amount was incurred in Nova Scotia.”
Information from ECCC illustrates the amount of rainfall and the geographical distribution across Cape Breton; in Table 5 and Figure 4.
Identifier Location Amount (mm) 8205702 SYDNEY CS 228.2
CAN-NS-60 Sydney Forks 213.1 8201780 ESKASONI FIRST NATION AUTOMATIC WEATHER STATION 199.6 CAN-NS-70 Georges River 151.9 CAN-NS-61 Aspy Bay 0.9 SW 149.9 8204495 PORT HAWKESBURY 137.4 CAN-NS-94 Margaree Forks 133.9 8202502 Ingonish Beach 123.7 Table 5. Listing of sites and precipitation amounts available from Environment Climate Change Canada.
Figure 4. Total Precipitation Plot for Oct 9-11 2018. Courtesy Environment Canada Atlantic Region. 5B. Analysis.
To understand how this storm differed from previous record storms, a review of the reported hourly rainfall amounts at several locations was made. As noted in Figure 6, the amount of hourly rainfall reported at Sydney CS station illustrates large values for the time period between 12-13 hours from the start of precipitation. While these amounts are smaller than those experienced during the 1981 event, the difference is that hourly amounts ranging from 10-20mm occurred through the 12 hours leading up to the most intense 2 hours (at 12-13 hours).
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As noted in Table 5, the 1981 event short duration values exceed 2016 until it reaches the 12hr and 24hr values (over half of the 24hr rainfall in 1981 fell in 2hrs). The persistence of rainfall at high or record values across the entire time of the October 2016 storm set it apart from the previous record-setting event in 1981.
Total Rainfall in Each Hour of Storm Sydney CS Oct 10-22 2016 30.0
25.0
20.0
15.0
10.0
5.0 Total Hourly Rainfall mm Rainfall Hourly Total 0.0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 Storm Duration hours
Figure 5. Hourly Rainfall for October 9-11 2016 Storm at Sydney CS.
Maximum Rainfall Sydney CS Duration 1hr 2hr 6hr 12hr 24hr 2016 25.3 49.1 101.2 189.3 224.1 1981 52.1 69.2 115.9 124.8 134.8 2012 48.8 66.2 NA NA NA
Table 6. Maximum Rainfall at Sydney CS 1961-2016 for 3 significant events. 5C. Risk Assessment: Tropical Cyclones
While the 224mm rainfall associated with the remnants of Hurricane Matthew could be considered a rare event, Eastern North America are threatened every year by tropical cyclones that possess large amounts of moisture. In fact, historical storms in other parts of Eastern Canada have also resulted in similar 24 hour rainfalls: Hazel in Toronto in 1954, Beth in Halifax in 1971, and Igor in Newfoundland in 2010.
While climate change may not increase the frequency of tropical cyclones, the combination of warmer sea surface temperatures and a warmer atmosphere that holds more moisture may result in more powerful storms with higher rainfall rates. Furthermore, some recent research suggests that changes in the atmospheric steering currents may result in slower moving storms (like Florence in 2018 and Harvey in 2017) bringing heavier rainfalls.
The risk of heavy rainfalls from tropical cyclones suggests that municipalities like CBRM would be prudent to prepare for these events by designing infrastructure and emergency response based on a 224mm, 24 hour rainfall. Furthermore, accepting that global temperatures will rise by 3 degrees C by 2100, intense storms like hurricanes will have the potential for rainfalls of some 20% higher (i.e. 269mm).
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6.0 Climate Baseline and Projections
To best determine future projections of any climate parameter a process that, first, creates a climate “baseline” for the site or region of concern is embarked on. Once a “baseline” that describes the overall climate for a variety of parameters is completed then a process of determining the future projections as they apply to the “baseline” is done based on best climate modeling practices. This section will provide current “baseline” values for precipitation (and rainfall) for the CBRM region. As well future projections of those values are generated as they apply to the five watercourse areas of concern to CBRM. 6A. Climate Baseline
Since the focus of this project is pluvial flooding, the climate “baseline” values will focus on precipitation over various time periods for the CBRM region. As described in Section 4B1, due to the sparseness of data throughout the CBRM, the strategy for generating a “baseline” is to identify CANGRID points co-located with the five watercourse sites. Since the “baseline” values are generally averages across months, seasons and years, the CANGRID approach provides relevant values for these sites.
Precipitation Amounts 1981-2010 (for sites based on CANGRID locations) Sydney Glace Bay North Sydney Spring (MAM) 353.1mm 359.7mm 350.9mm Summer (JJA) 288.3mm 287.2mm 288.9mm Fall (SON) 405.6mm 410.7mm 410.5mm
Winter (DJF) 415.9mm 423.0mm 418.1mm Annual 1459.2mm 1476.9mm 1464.5mm 3-day Max Accumulation 114.8mm 115.3mm 120.5mm
Table 7. Precipitation Amounts for 3 proxy locations in CBRM (climate baseline)
6B. Climate Projections
To provide relevant projections of change, to both the average climate parameters as well as the extremes, state-of- the-art global climate model output must be utilized. Such output can be drawn from each of the over 40 global climate models available (IPPC, 2013).
A general description of global climate models and the process currently adopted by world climate researchers to generate consistent model output has been added as Appendix B. of this report.
Most global models generate projections of annual precipitation over southern Canada in a range from 5-10% increase by 2100. Some models have projected increases over other geographical areas, mostly over northern Canada, which exceed 30-40%. Theoretically, as the atmosphere warms, its capacity to hold moisture will follow the Clausius Clapeyron relationship, where, as temperature increases by 1C, the atmosphere’s capacity increases by 7%. If global atmospheric temperature increase by 3C by 2100 then the atmosphere can hold 21% more moisture as water vapour. Based on this theory, the amount of potential precipitation by 2100 could increase by 21%. Obviously there are other factors at play, however, as we approach 2100 we should expect to see annual increases in precipitation approaching this value.
To generate values for this report, two climate parameter projection Tools were accessed and utilized to build the Projections Tables shown below:
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6B1. Risk Sciences International (RSI) – Climate Change Hazards Information Portal (CCHIP)
For this project, the authors are utilizing expertise in interpretation and projection of Global Climate Model Output. RSI has developed and made available for use a Climate Change Hazards Information Portal (CCHIP) (see Figure 4). This Portal allows users to access climate data as well as climate projections of a large variety of climate parameters (and extremes) based on the latest global climate model output. This project has utilized CCHIP to generate projections of seasonal and annual precipitation.
Figure 6. Screenshot of CCHIP Dashboard showing temperature output for Sydney Airport.
6B2. Western University and the Canadian Water Network – IDF_CC Tool
To project values of intensity, duration and frequency of extreme precipitation, other techniques can be utilized. Western University and the Canadian Water Network have partnered to generate the IDF_CC Tool. This project has utilized this tool to provide projections of short duration/high intensity precipitation.
Website: http://www.idf-cc-uwo.ca/
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Figure 7. Screenshot of Map Interface for IDF_CC tool. Courtesy Western University & Canadian Water Network.
6B3. CBRM Projections
To generate projections for average rainfall over the CBRM, future changes as developed from climate model output was applied to the “baseline” values. The CCHIP tool was utilized to access the appropriate values based on the 40- model ensemble. As noted in Appendix B, the atmosphere is currently experiencing greenhouse gas concentrations that follow a “Representative Concentration Pathway (RCP)” similar to one described as producing a warming of 8.5 watts per sqm. This pathway is referred to as RCP8.5 and is commonly understood to be the “high emission” scenario. Projections extracted from CCHIP are based on the RCP8.5.
The CCHIP tool has the flexibility to provide output over the next century in 3 tridecadal sections, the 2020s (2011- 2040), the 2050s (2041-2070) and the 2080s (2071-2100), thus maintaining the equivalent time period as the average annual rainfall values (1981-2010).
CBRM Sites Avg Ann Rain 2020s 2050s 2080s 1981-2010 Sydney 1459.2mm 1491.3 1535.0 1578.8 Glace Bay 1476.9mm 1509.4 1553.7 1598.0 North Sydney 1464.5mm 1496.7 1540.6 1584.6
Table 8. Projections of Average Annual precipitation for CBRM sites (based on CCHIP tool output).
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To generate projections for the 24hr extreme precipitation values, the IDF_CC tool was accessed. In order to maintain a level of compatibility between output from these separate tools, an ensemble average approach was selected in the IDF_CC tool and the same high GHG emission scenario was used, i.e. RCP 8.5. However the IDF_CC tool only allowed for 2 time periods across the next 100 years, i.e. 2010-2060 and 2050-2100, both 50 years in duration.
Sydney CS 24hr Current 2010-2060 2050-2100 2 67.6 75.7 89.7 5 82.5 97.0 114.1 10 92.3 108.8 130.5 25 104.8 129.0 149.6 50 114.0 145.7 161.1 100 123.2 162.8 171.8
Table 9. Projections of 24hr extreme rainfall at Sydney CS site (based on IDF_CC tool).
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7.0 Sea Level Rise and High Water
The combination of sea level rise over the next century and projected increasing storm surge activity will result in ever increasing high water events for coastal Nova Scotia. Table 10 combines projected sea level rise, crustal subsidence (sinking land) and storm surge events resulting in increased high water events for the coastline of Nova Scotia in the vicinity of Sydney.
Since high water events are presumed to occur at the timing of high tide, a Highest High Water Level (HHWLT) of 1.32 m Chart Datum (CD) was used to create the Sydney values (from Richards & Daigle, 2011)."
From Richards & Daigle, 2011:
“In more practical terms, the HHWLT value is representative of the highest astronomical tide possible for a given location; the CD-zero value is representative of the lowest possible tide for a given location; the Mean Water Level (MWL) value is representative of the average of HHWLT and CD-zero; and the CGVD28-zero value represents approximately the MWL value, but there are varying differences depending on location (normally within 10-25cm).”
For further purposes of clarity, Appendix E includes an explanation of the difference in calculation of the Chart Datum and geodetic heights for mapping purposes as it applied in Halifax Harbour from the 2009 Report by Forbes et al.
Extreme Total Sea Level (High Water) (metres CD) – Sydney
Return 2000 2025 2055 2085 2100 Period 10-Year 1.95 ± 0.10 2.11 ± 0.13 2.40 ± 0.25 2.81 ± 0.46 3.05 ± 0.58
25-Year 2.04 ± 0.10 2.20 ± 0.13 2.49 ± 0.25 2.90 ± 0.46 3.14 ± 0.58 50-Year 2.10 ± 0.10 2.26 ± 0.13 2.55 ± 0.25 2.96 ± 0.46 3.20 ± 0.58 100-Year 2.17 ± 0.10 2.33 ± 0.13 2.62 ± 0.25 3.03 ± 0.46 3.27 ± 0.58
Table 10. High Water Projected Values Based on Sydney NS (from Richards & Daigle, 2011).
As illustrated in Table 10, the current 100-year high water event (2.17m CD) becomes a 25-year event (2.20m CD) by 2025 and all events reach new values after 2025.
November 2018 (Updated March 2019) 21
8.0 Summary of Results
As we progress through the 21st century, extreme events, especially heavy precipitation events, will continue to increase in frequency and intensity. The impacts on the CBRM built and natural environment will become more severe unless various levels of adaptation measures are developed and implemented. The following is a summary of the historical and projected extreme precipitation results as they apply to risk assessment of the five target watercourses in CBRM.
Average Annual Precipitation Projections:
As noted in Table 8, average annual precipitation for site around Sydney is projected to increase by approximately 8% by 2100 utilizing an ensemble of models. Given the potential application of the Clausius Clapeyron relationship, these projections appear too conservative. Projected increases approaching 20% by 2100 would be more appropriate for these averages. Also other factors come into play when considering these projections, including location (southern or northern Canada), etc.
Extreme Rainfall Projections:
As noted in Table 9, the projected increases of the 24hr extreme rainfall were driven by an ensemble of models and focused on the “high emission” scenario, RCP 8.5. Such projections increased the intensity of these events by 30-35% by 2100. Such increases, also reflecting on the Clausius Clapeyron relationship, seem high given the available moisture projected in the atmosphere.
However, there are other problems with these projections. The base IDF curve used for this process is from Sydney CS station and uses data from 1961 to 2014. Therefore the values do not consider the more recent heavy rainfall event of October 2016. By not including such an event, any analysis and projection of heavy rainfall amounts should be treated as conservative.
Conclusions:
1. Current projections of both the average annual values and the extreme intensity and frequency values for CBRM should be treated as conservative. 2. Based on the forensic analysis of the October 2016 event and its comparison to the 1981 event (which would have been included in the 2014 IDF curve for Sydney), none of the above projections are capturing the true nature of an extreme event for Sydney in the future. 3. The 24hr amount for the Oct 2016 event at Sydney (224.1) should be considered the minimum 24hr amount for any future planning in the natural and built environment. It is recommended that this amount be increased by 20% by 2100 to allow for increased precipitation due to climate change. 4. The hourly rate of precipitation (as illustrated by both the 1981 and 2016 event) should also be increased by the same 20% to reflect the potential for increased overland flooding as well as flash flooding in narrow watercourses.
November 2018 (Updated March 2019) 22
9.0 References.
1. IPCC, 2012: Summary for Policymakers. In: Managing the Risks of Extreme Events and Disasters to Advance Climate Change Adaptation [Field, C.B., V. Barros, T.F. Stocker, D. Qin, D.J. Dokken, K.L. Ebi, M.D. Mastrandrea, K.J. Mach, G.-K. Plattner, S.K. Allen, M. Tignor, and P.M. Midgley (eds.)]. A Special Report of Working Groups I and II of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 3-21. 2. Environment Canada. (2006) Climate data online. http://www.climate.weatheroffice.ec.gc.ca/climateData/canada_e.html, accessed December 2006. 3. Vincent, L. A., X. L. Wang, E. J. Milewska, H. Wan, F. Yang, and V. Swail , 2012. A second generation of homogenized Canadian monthly surface air temperature for climate trend analysis, J. Geophys. Res., 117, D18110, doi:10.1029/2012JD017859. 4. Mekis, É and L.A. Vincent, 2011: An overview of the second generation adjusted daily precipitation dataset for trend analysis in Canada. Atmosphere-Ocean 49(2), 163-177. 5. Environment Canada. (2013) Climate Change Scenarios Network (CCSN). http://www.cccsn.ec.gc.ca/ 6. Richards, William, Real Daigle, 2011. Scenarios and Guidance for Adaptation to Climate Change and Sea-Level Rise – Nova Scotia and Prince Edward Island Municipalities. Prepared for Nova Scotia Dept. of Environment, Atlantic Canada Adaptation Solutions Association, August 31, 2011. 7. Hanson, Rebecca, W.G. Richards, 2007. Atmospheric Hazards: Consecutive Wet and Dry Days in Atlantic Canada. Meteorological Service of Canada – Atlantic Science Report Series 2007-02 May 2007. 8. The Representative Concentration Pathways: an overview, van Vuuren et al. 2011, Climate Change (2011) 109:5-31, DOI 10.1007/s10584-011-0148-z 9. IPCC, 2013: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 1535 pp. 10. J. Sillmann, Kharin, V., Zwiers, F., Zhang, X., Bronaugh, D. Climate extreme indices in the CMIP5 multi-model ensemble. Part 2: Future climate projections, Oct, 2012. Draft Online. http://www.cccma.ec.gc.ca/data/climdex/pdf/Sillmann-et-al_CMIP5-extremes- indices_part2_projections_revised.pdf 11. McKenney, D.W.; Kesteven, J.L.; Hutchinson, M.F.; Venier, L. 2001. Canada's plant hardiness zones revisited using modern climate interpolation techniques. Can. J. Plant Science. 81: 139-143. 12. James, T.S., Henton, J.A., Leonard, L.J., Darlington, A., Forbes, D.L., and Craymer, M., 2014. Relative Sea-level Projections in Canada and the Adjacent Mainland United States; Geological Survey of Canada, Open File 7737, 72 p. doi:10.4095/295574 13. Mark W. Shephard, Eva Mekis, Robert J. Morris, Yang Feng, Xuebin Zhang, Karen Kilcup & Rick Fleetwood (2014): Trends in Canadian Short-Duration Extreme Rainfall: Including an Intensity-Duration-Frequency Perspective, Atmosphere-Ocean, DOI: 10.1080/07055900.2014.969677 14. CSA Standards, 2012. PLUS 4013-12. Technical Guide, Development, interpretation, and use of rainfall intensity-duration-frequency (IDF) information: Guideline for Canadian water resources Practitioners. 15. Personal Conversation, May 2018. Comparison of 24-hour (from TBRG) and one-day (from daily data) extreme rainfall results for Sydney CS events 1981 vs 2016. Bridget Thomas, Client Services Operations Atlantic, Environment Canada. 16. Forbes, D.L., Manson, G.K., Charles, J., Thompson, K.R., Taylor, R.B. 2009: Halifax Harbour extreme water levels in the context of climate change: scenarios for a 100-year planning horizon, Geological Survey of Canada, Open File 6346, 21p.
November 2018 (Updated March 2019) 23
10.0 List of Figures.
Figure 1. Example of Grid-boxes over Cape Breton used for CANGRID.
Provided by Neil Comer, RSI, Toronto 10 Figure 2. Radar Return Composite (RDPA) for CBRM Oct 11 2016, Environment Canada 11 Figure 3. Extreme Precipitation Estimates: 24-hr 100-yr Event 13 Figure 4. Total Precipitation Plot for Oct 9-11 2018. Courtesy Environment Canada Atlantic Region 15
Figure 5. Hourly Rainfall for October 9-11 2016 Storm at Sydney CS 16
Figure 6. Screenshot of CCHIP Dashboard showing temperature output for Sydney Airport 18 Figure 7. Screenshot of Map Interface for IDF_CC tool. Courtesy Western University & Canadian Water Network 19
November 2018 (Updated March 2019) 24
11.0 List of Tables
Table 1. Locations of five watercourses of concern in CBRM 5 Table 2. Maximum 24hr Rainfall Records prior to 2016 9 Table 3. CANGRID Proxy Sites for CBRM 10 Table 4. Sydney CS IDF Table Rainfall in mm (based on 2014 data). Courtesy ECCC 12 Table 5. Listing of sites and Precipitation amounts available from Environment Climate Change Canada 15 Table 6. Maximum Rainfall at Sydney CS 1961-2016 for 3 significant events 16 Table 7. Precipitation Amounts for 3 proxy locations in CBRM (climate baseline) 17 Table 8. Projections of Average Annual precipitation for CBRM sites (based on CCHIP tool output) 19 Table 9. Projections of 24hr extreme rainfall at Sydney CS site (based on IDF_CC tool) 20 Table 10. High Water Projected Values Based on Sydney NS (from Richards & Daigle, 2011). 21
November 2018 (Updated March 2019) 25
12.0 Appendix A.
List of Observing Sites CBRM
Site Number Site Name Duration
8205702 Sydney CS 1961-present 8205703 Sydney Airport 1941-present
CB Weather Sydney Forks 2011-present Network CAN-NS-60 Sydney Forks
CB Weather Port Caledonia 2013- present Network 8201780 ESKASONI FIRST NATION AUTOMATIC 2011-present
WEATHER STATION 8203163 Louisbourg 1972-2013
CAN-NS-70 Georges River CAN-NS-61 Aspy Bay 0.9 SW 8204495 Port Hawkesbury 2010-present 8203422 Margaree Forks 1960-2004 CAN-NS-94 Margaree Forks 8202502 Ingonish Beach 2000-present 82044656 Point Aconi 1990-2013 8200300 Baddeck 1915-2000 820301 Baddeck Bell 2000-present
November 2018 (Updated March 2019) 26
Map of CBRM Watercourses
November 2018 (Updated March 2019) 27
13. Appendix B. – Global Climate Model Procedures
Global Climate Models
Determination of future climate can only be done using mathematical models. Such models simulate how climate behaves over long periods of time across the globe. Each model does numerous calculations on a “grid” that covers the earth. Values are then averaged into “grid boxes”, including temperature and precipitation change expected for that area.
International effort through the Coupled Model Intercomparison Project (CMIP5) has utilized over 40 separate climate models to provide projections out to 2100 in 30-year time periods (2020s, 2050s and 2080s) for a variety of climate parameters. To do so, these models must base their future projections on scenarios of Greenhouse Gas (GHG) concentrations.
Example of Grid-boxes over Canada, based on Canadian Global Climate Model CGCM3. Colours refer to projected annual average temperatures for 2020s within the grid –boxes. (Canadian Climate Centre for Modeling and Analysis (CCCma) website.)
The concentration scenarios were developed to allow all of the international models to utilize the same potential Greenhouse Gas “pathway”, and hence generate comparable results. Officially these concentration scenarios are called “Representative Concentration Pathways (RCPs)” and provide a set of potential GHG concentration futures. For example, RCP8.5 describes the concentration of GHGs as they increase over the next hundred years in order to generate a radiative forcing of 8.5 watts per square meter. Such a forcing would result in atmospheric warming of 4- 6C by 2100. This scenario is seen by the research community as a “high concentration scenario”. Even so, on a global scale, GHG (more specifically CO2) concentrations for the past 5-10 years have been tracking this path.
November 2018 (Updated March 2019) 28
Estimated CO2 emissions over the past three decades compared with the IS92, SRES and the RCPs.
Since each model output is a valid future climate, assessing which model results would be most appropriate for specific uses, especially assessment processes, can be difficult at best. To provide better guidance on which models to use, the international climate modeling community decided to use standardized procedures and identical GHG emission scenarios (RCP2.6, 4.5, 6 & 8.5) to produce future climate projections.
Those results were published in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) in 2014. The IPCC then placed the model results on a data distribution website so that any organization requiring future climate projections from one or all of these models could access them. Output from these models was used in this project to generate projections for the Nova Scotia Mainland area.
Since each model output is a valid future climate, assessing which model results would be most appropriate for the Mainland area requires applying current “ensemble” methods. By doing so lessens uncertainty and provides an appropriate range of results.
A listing of the current modeling centres and the model experiments they generated for IPCC Fifth Assessment Report (AR5) is in Appendix C. Ensemble Approach
The “ensemble” approach is the current “standard” for averaging the output from the suite of 40 models available through the IPCC process. Such a technique increases confidence in the eventual values produced. Most models are projecting a warmer and wetter future, globally, but they also vary from one another. Since all model results are equally valid, the most effective way to lessen uncertainty and any errors inherent in each model is to produce an “ensemble average”.
November 2018 (Updated March 2019) 29
14. Appendix C. – List of Models
Modeling Centre Models Institution BCC BCC-CSM1.1 Beijing Climate Centre, China BCC-CSM1.1(m) Meteorological Administration CCCma CanAM4 Canadian Centre for Climate Modeling CanCM4 and Analysis CanESM2 CMCC CMcc-CESM Centro Euro-Mediterraneo per I CMCC-CM Cambiamenti Climatici CMSS-CMS CNRM-CERFACS CNRM-CM5 Centre National de Recherches CNRM-CM5-2 Meteorologiques / Centre Europeen de Recherches et Formation Avancees en Calcul Scientifique COLA and NCEP CFSv2-2011 Centre for Ocean-Land-Atmosphere Studies and National Centres for Environmental Prediction CSIRO-BOM ACCESS1.0 Commonwealth Scientific and Industrial ACCESS1.3 Research Organization and Bureau of Meteorology, Australia CSIRO-QCCCE CSIRO-Mk3.6.0 Commonwealth Scientific and Industrial Research Organization and Queensland Climate Change Centre of Excellence, Australia
EC-Earth EC-Earth EC-Earth Consortium FIO FIO-ESM The First institute of Oceanography, China GCESS BNU-ESM College of Global Change and Earth System Science, Beijing Normal University INM INM-CM4 Institute for Numerical Mathematics, Russian Academy of Science IPSL IPSL-CM5A-LR Institut Pierre-Simon Laplace, Paris, IPSL-CM5A-MR France IPSL-CM5B-LR LASG-CESS FGOALS-G2 Institute of Atmospheric Physics, Chinese Academy of Sciences and CESS, Tsinghua University LASG-IAP FGOALS-gl Institute of Atmospheric Physics, FGOALS-s2 Chinese Academy of Sciences MIROC MIROC4h Atmosphere and ocean Research MIROC5 Institute (University of Tokyo), National MIROC-ESM Institute for Environmental Studies and November 2018 (Updated March 2019) 30
MIROC-ESM-CHEM Japan Agency for Marine-Earth Science and Technology MOHC HadCM3 Met Office Hadley Centre (Instituto HadCM3Q Nacional de Pasquisas Espacials, Brazil) HadCM2-A HadCM2-CC HadCM2-ES MPI-M MPU-ESM-LR Max Planck Institute for Meteorology, MPI-ESM-MR Hamburg Germany MPI-ESM-P MRI MRI-AGCM3.2H Meteorological Research Institute, MRI-AGCM3.2S Japan MRI-CGCM3 MRI-ESM1 NASA GISS GISS-E2-H NASA Goddard Institute for Space GISS-E2-H-CC Studies), New York, NY, USA GISS-E2-R GISS-E2-R-CC NASA GMAO GEOS-5 NASA Global Modeling and Assimilation Office (GMAO), Maryland, USA NCAR CCSM4 National Centre for Atmospheric Research, Boulder, Colorado NCC NorESM1-M Norwegian Climate Centre NorESM1-ME NICAM NICAM.9 Nonhydrostatic Icosahedral Atmospheric Model Group NIMR/KMA HadGEM2-AO National Institute of Meteorological Research, Korea Meteorological Administration NOAA GFDL GFDL-CM2.1 Geophysical Fluid Dynamics Laboratory, GFDL-CM3 Princeton University, NJ GFDL-ESM2G GFDL-ESM2M GFDL-HIRAM-C180 GFDL-HIRAM-C360 NSF-DOE-NCAR CESM1(BGC) National Science Foundation, CESM1(CAM5) Department of Energy, National Center CESM1(CAM5.1, FV2) for Atmospheric Research, USA CESM1(FASTCHEM) CESM1(WACCM)
November 2018 (Updated March 2019) 31
15. Appendix D. Graphical Representation of IDF Curves for Sydney CS.
IDF Curve for Sydney CS NS valid 2014.
November 2018 (Updated March 2019) 32
16.0 Appendix E. Chart Datum vs CGVD28
Extracted from:
Pages 8-9
Vertical datum and water levels
The definition of vertical datum is critical to any discussion of tides and flood levels. Navigation charts use a local datum defined to be close to lower low-water at large tides (i.e. rarely uncovered). The water levels recorded at the Halifax tide gauge and the tidal predictions in the published tide tables are all referred to this local Chart Datum (CD).
Mean sea level (MSL) lies above Chart Datum. The Canadian Geodetic Vertical Datum 1928 (CGVD28) was originally defined as mean sea level measured in 1928 at two tide gauges on the Pacific coast and three on the Atlantic coast, one of which was Halifax. The mean sea level at Halifax in 1928 was 0.79 m above present Chart Datum, effectively the same as the 0.8 m separation between CD and CGVD28 (Fig. 5). Mean sea level is now above CGVD28 (Fig. 5) with a mean of 1.02 m CD and standard deviation of 0.02 m over the 5 years 1999-2003……
Fig. 5. Vertical datums and separations with key water levels in Halifax Harbour.
November 2018 (Updated March 2019) 33
……..Because, as these data show, mean sea level has been rising against the coast in the Halifax region, Chart Datum was redefined in 1987 to be 0.29 m higher than before (Fig. 5). Higher high water at large tides (HHWLT) is 2.1 m CD (1.3 m above CGVD28) and the record water level in Halifax Harbour (during Hurricane Juan in 2003) was 2.91 m CD (2.11 m above CGVD28).
All water-level data in this (extracted) report are referenced to the present (post-1987) Chart Datum or to CGVD28 (which is unchanged). The data were obtained from the on-line data base maintained by the Canada Department of Fisheries and Oceans (http://www.meds-sdmm.dfo-mpo.gc.ca/isdm-gdsi/index-eng.html, most recently accessed 2009-10-09).
November 2018 (Updated March 2019) 34
UNCLASSIFIED National Disaster Mitigation Program (NDMP) Risk Assessment Information Template
Risk Event Details
Provide the start and end dates of the selected event, based on Start and End Date Start Date: 10/10/2016 End Date: 11/10/2016 historical data. - Flooding caused by historical rainfall event (Hurricane Matthew) Provide details about the risk, including: - The potential risk was known (heavy rain) but not the magnitude of the risk • Speed of onset and duration of event; - Major flooding: Erosion, damaged infrastructure, flooded houses and interrupted Severity of the Risk Event • Level and type of damaged caused; services (closed schools, community centres, churches, etc.) • Insurable and non-insurable losses; and - Heavy winds caused fallen trees and loss of power • Other details, as appropriate. - Sea level surge caused backing in sewer system; contamination and increased flooding - Cape Breton Regional Police blocked off streets and directed traffic away from danger zones Provide details on how the defined geographic area continued its - Regional call centre for response was set up Response During the Risk Event essential operations while responding to the event. - CBRM and NSTIR Operations staff on the ground, responding to calls
-Waited for flood water to recede.When it was safe, debris was removed from culverts and from the streets to help the watershed drain naturally Recovery Method for the Risk - Application for federal and provincial disaster relief funding Provide details on how the defined geographic area recovered. Event - Private insurance claims - Some building demolished, residents resettled. - Physical restoration/repairs as required. - Insurance claims: $2.06M - Disaster Relief Funding (DFAA): $1.71M Recovery Costs Related to the Provide details on the costs, in dollars, associated with implementing - Total: $3.77M Risk Event recovery strategies following the event.
- Approximately 24-48 h for majority of power restored - Unknown as for the damaged infrastructure and flooded houses and buildings Recovery Time Related to the Provide details on the recovery time needed to return to normal - Months for restoration of damaged physical infrastructure Risk Event operations following the event. - Some buildings required demolition/resettlement.
Page 1 of 20 UNCLASSIFIED National Disaster Mitigation Program Risk Assessment Information Template
Risk Event Identification and Overview
- Renwick Brook, Reservoir Brook, Cadegan Brook, Prime Brook and Smelt Brook Watersheds - Cape Breton Regional Municipality - Nova Scotia (Cape Breton) Provide a qualitative description of the defined geographic area, including: - Communities: Sydney, New Waterford, Glace Bay and North Sydney • Watershed/community/region name(s); - Population size: Approximately 94,300 • Province/Territory; - Population variances: Population increase between April through November (Tourism Season) • Area type (i.e., city, township, watershed, organization, etc.); - Main economic areas: Commercial Street, McKeen Street, Union Street, Reserve Street, Glace Bay • Population size; Harbour, Membertou Commercial centre, Kings Road • Population variances (e.g., significant change in population between summer and winter - Special consideration areas: Fisheries, Membertou First Nation, Water Supply Reservoirs months); - Estimate of the annual operating budget of the area : Approx. $147M • Main economic areas of interest; • Special consideration areas (e.g., historical, cultural and natural resource areas); and an • Estimate of the annual operating budget of the area.
Methodolgies, processes and analyses
- Climate Observations and Projections in Support of Flood Risk Assesment for Cape Breton Regional Municipality (ClimAction Services, 2018), completed as part of the current NDMP Project - FRIP Planning Study for adjacent Wash Brook Watershed, 2018 Provide the year in which the following processes/analyses were last completed and state the methodology(ies) used: • Hazard identification; • Vulnerability analysis; • Likelihood assessment; • Impact assessment; • Risk assessment; • Resiliency assessment; and/or • Climate change impact and/or adaptation assessment. Note: It is recognized that many of the processes/analyses mentioned above may be included within one methodology.
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Hazard Mapping
To complete this section: • Obtain a map of the area that clearly indicates general land uses, neighbourhoods, landmarks, etc. For clarity throughout this exercise, it may be beneficial to omit any non-essential information from the map intended for use. Controlled photographs (e.g. aerial photography) can be used in place of or in addition to existing maps to avoid the cost of producing new maps. • Place a grid over the maps/photographs of the area and assign row and column identifiers. This will help identify the specific area(s) that may be impacted, as well as additional information on the characteristics within and affecting the area. • Identify where and how flood hazards may affect the defined geographic area. • Identify the mapped areas that are most likely to be impacted by the identified flood hazard. Map(s)/photograph(s) can also be used, where appropriate, to visually represent the information/prioritization being provided as part of this template.
Hazard identification and prioritization
(1) Urban storm surge flooding (near the outlet of the watershed, some of which have houses are very List known or likely flood hazards to the defined geographic area in order of proposed priority. densely located); (2) Reservoir dyke/Highway damage or breach; (3) Riverine flooding and damaged For example: (1) dyke breach overland flooding; (2) urban storm surge flooding ; and so on. infrastructure such as culverts, streets and buildings; (4) Water treatment plant near one of the reservoir outlets; (5) Localized flooding (undersized culverts) - Debris washing; (6) School, sports fields and parks, commercial areas (impervious and likely to generate a considerable amount of runoff) (1) Different fisheries establishments directly in the harbour area and most of the businesses present Provide a rationale for each prioritization and the key information sources supporting this on the watershed are on Commercial Street North-East of the harbour (Commercial Street goes over rationale. Glace Bay Harbour via a bridge) - Residential buildings are very close to the Glace Bay shoreline and extremely vulnerable to storm surge - Glace Bay Hospital and Seaview Manor Home For Special Care also very close to the coastline (2) Watersheds are composed of many different reaches and many of these flow very close to high density residential areas. Many undersized, aging or damaged culverts observed. (3)Flooding in and around a hospital could impair vital activities and access (medication and equipment deliveries) and could have serious consequences on the overall flooding of the watershed (4) Reserve Street commercial area is in a low-lying area (flooded in 2016) - The fire station is located in that same area and rescue activities could be affected by impaired access *References: Oct 10 2016 Rainfall Event Internal Review CBRM Public Works document; Site visit April 6, 2018; CBRM NDMP Stakeholder Workshop, June 25, 2018.
Risk Event Title
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Flooding event caused by record-breaking rainfall due to a low pressure system cause by Hurricane Identify the name/title of the risk. An example of a risk event name or title is: "A one-in-one Matthew. (225 mm - an all-time record for Sydney, the previous record being 128 mm, set in 1981) hundred year flood following an extreme rain event." (Source:TWN)
Type of Flood Hazard
Primary Flood Risk Under Review: Riverine flooding; Urban run-off Identify the type of flood hazard being described (e.g., riverine flooding, coastal inundation, urban Additional Flood Risks: Coastal inundation; Reservoir dyke breach; Stormwater Detention Pond run-off, etc.) breach
Secondary hazards
- Flooded homes and buildings Describe any secondary effects resulting from the risk event - Sewage backwash and contamination near the coast line (e.g., flooding that occurs following a hurricane). - Contamination of multiple river systems and harbours as well as the Atlantic Ocean - Landslides, road damage, culvert damage, etc. - Washouts causing further build-up of debris and damage downstream.
Primary and secondary organizations for response
Cape Breton Regional Municipality; Nova Scotia Department of Transportation (Roads/Highway Identify the primary organization(s) with a mandate related to a key element of a natural disaster Infrastructure); Cape Breton Regional Police; Membertou First Nation emergency, and any supporting organization(s) that provide general or specialized assistance in Province of Nova Scotia Emergency Management Office: Emergency response (provincial level) response to a natural disaster emergency. Nova Scotia Environment: Response to Contaminant release to freshwater environment Department of Fisheries and Oceans; Response to Contaminant release to marine environment Public Safety Canada (Federal): National Disaster Response
Risk Event Description
Description of risk event, including risk statement and cause(s) of the event
Page 4 of 20 UNCLASSIFIED National Disaster Mitigation Program Risk Assessment Information Template
Potential flooding or breaching of major watercourses within five (5) key watersheds in the Provide a baseline description of the risk event, including: Municipality during major storm events, as well as areas near the coastline. • Risk statement; Flooding is attributed to low-lying areas, the proximity to the shoreline (storm surge on land and via • Context of the risk event; drainage pipes), undersized culverts along the brook and near the outlet of the watershed, debris, • Nature and scale of the risk event; washout and corresponding channel blockages. • Lead-up to the risk event, including underlying cause and trigger/stimulus of the risk event; and Factors affecting future events: Climate Change (increased intensity and frequency of meteorological • Any factors that could affect future events. events, including rainfall events); urban growth/development and increased impervious surfaces; Note: The description entered here must be plausible in that factual information would support Aging infrastructure; failure of undersized or deteriorated infrastructure. such a risk event.
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Location
Province: Nova Scotia Municipalities: Cape Breton Regional Municpality Provide details regarding the area impacted by the risk event such as: Region: Cape Breton • Province(s)/territory(ies); District: Sydney, New Waterford, Glace Bay, North Sydney • Region(s) or watershed(s); Region or watershed: Renwick Brook, Reservoir Brook, Cadegan Brook, Prime Brook and Smelt • Municipality(ies); Brook Watersheds • Community(ies); and so on.
Natural environment considerations - Topographically low-lying areas - Costal outlets influenced by tidal and storm surge conditions - Most watersheds drain through a series of small Basins - Upper reaches of the watersheds are largely rural/semi rural undeveloped forests which transition Document relevant physical or environmental characteristics of the defined geographic area. into Urban residential and commercial development. - Sedimentation/infill in downstream drainage system - Urbanized watercourses traversing through residential and commercial areas. - Some stormwater infrastructure appears to cross private property and possibly even below/in close proximity to residential dwellings. - Watercourse crossings at key transportation/emergency routes
Meteorological conditions
- High-intensity short duration rainfall events for the lower urban reaches or lower-intensity, long duration events (likely due to a low pressure system cause by a hurricane) for the whole system. - Spring freshet and rain on snow event - Storm surge conditions Identify the relevant meteorological conditions that may influence the outcome of the risk event. - High winds (debris in watercourses).
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Seasonal conditions
- The Atlantic storm season (approximately the beginning of the summer to the end of Fall). However, subtropical storms have also developed outside of that period. - Storm surge conditions during hurricane events Identify the relevant seasonal changes that may influence the outcome of the risk assessment of - Frozen ground: decreased infiltration, increased surface runoff a particular risk event. - High groundwater table in the spring due to seasonal runoff - Snow pack
Nature and vulnerability
Population density: Medium density residential/Low density commercial/Low density industrial. Watersheds are composed of high density residential areas and areas of natural land (woods and wetlands). Vulnerable populations: Residents living near the outlet of the watershed or near undersized or damaged culvert systems, School near impervious commercial centres, hospital near reservoir, water treatment plant near reservoir, fire station along watercourse, at-risk populations that could be isolated from emergency services by a road washout. Document key elements related to the affected population, including: Degree of urbanization: Moderate degree of urbanization • Population density; Key local infrastructure: • Vulnerable populations (identify these on the hazard map from step 7); - Cape Breton Regional Hospital; Glace Bay Hospital; Water treatment plants; Seaview Manor Home • Degree of urbanization; For Special Care and Several other care centres and guest homes; Shipyard Elementary School; • Key local infrastructure in the defined geographic area; Malcolm Munroe Memorial Jr High School; Glace Bay Elementary School; Sydney River Trestle • Economic and political considerations; and Bridge; Glace Bay Fire Hall (First responders); Commercial areas in multiple locations; Transportation • Other elements, as deemed pertinent to the defined geographic area. Routes (incl. Highway 125; Reservoir Road; Kings Road). Economic considerations: -Commercial areas in low-lying land, commercial and industrial (fisheries) activities located near the coastline and Harbour Environmental considerations: - Contaminants (ie. residential oil tanks) discharge into Brooks, Harbours, and the Atlantic Ocean - Sediment/infill in downstream parts of the watershed - Contamination and sedimentation in the different wetland areas - Flooding of transportation routes can also collect excess debris and roadway contaminants
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Asset inventory
Identify the asset inventory of the defined geographic area, including: Transportation Routes: Highway 125 EB (Public Transit and Commuter Route; Traffic congestion; - • Critical assets; Emergency evacuation route); Dominion Street (emergency evacuation route if Reserve Street is • Cultural or historical assets; flooded like it was in 2016); 100-series highways • Commercial assets; and Hospitals/Care Facilities: Cape Breton Regional Hospital; Glace Bay Hospital; Seaview Manor Home • Other area assets, as applicable to the defined geographic area. For Special Care Public Services: Fire Stations (in low-lying area); Schools Key asset-related information should also be provided, including: Cultural/Historical: Various religious establishments; Membertou First Nations Community • Location on the hazard map (from step 7); Commercial assets: Fisheries near the harbour; Multiple commercial areas • Size; Private property: Residential properties located along watercourses, subject to flooding • Structure replacement cost; Utilities:Culvert systems; Local overhead power and communication; potable water services; sanitary • Content value; system backup. • Displacement costs; Note: given the high-level nature of Stream 1 Risk Assessment, in the absence of flood mapping, • Importance rating and rationale; some of the requested asset information is unavailable or has not been assessed at this initial stage. • Vulnerability rating and reason; and • Average daily cost to operate.
A total estimated value of physical assets in the area should also be provided. Other assumptions, variability and/or relevant information
See page 19 Identify any assumptions made in describing the risk event; define details regarding any areas of uncertainty or unpredictability around the risk event; and supply any supplemental information, as applicable.
Existing Risk Treatment Measures
Heightened response following Hurricane Matthew. CBRM set up a call centre for emergency flood response. Identify existing risk treatment measures that are currently in place within the defined geographic Federal/provincial disaster relief funding area to mitigate the risk event, and describe the sufficiency of these risk treatment measures. CBRM currently studying and implementing mitigation measures at the adjacent Wash Brook watershed.
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Likelihood Assessment
Return Period
For the purposes of the current risk assessment, the risk event is considered to be greater than or Identify the time period during which the risk event might occur. For example, the risk event equal to the 1:100 year rainfall event (225 mm +) described is expected to occur once every X number of years. Applicants are asked to provide the X value for the risk event.
Period of interest
Applicants are asked to determine and identify the likelihood rating (i.e. period of interest) for the risk event described by using the likelihood rating scale within the table below.
Likelihood Rating Definition
5 The event is expected and may be triggered by conditions expected over a 30 year period.
4 The event is expected and may be triggered by conditions expected over a 30 - 50 year period.
3 The event is expected and may be triggered by conditions expected over a 50 - 500 year period. 3
2 The event is expected and may be triggered by conditions expected over a 500 - 5000 year period.
1 The event is possible and may be triggered by conditions exceeding a period of 5000 years. Selection of mitigation measures must consider impacts from increased duration/intensity of pluvial events due to climate change Hurricane Matthew (2016) - 225 mm - an all-time record for Sydney, the previous record being 128 mm, set in 1981. Provide any other relevant information, notes or comments relating to the likelihood assessment, as applicable.
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Impacts/Consequences Assessment
There are 12 impacts categories within 5 impact classes rated on a scale of 1 (least impacts) to 5 (greatest impact). Conduct an assessment of the impacts associated with the risk event, and assign one risk rating for each category. Additional information may be provided for each of the categories in the supplemental fields provided.
A) People and societal impacts
Risk Assigned Definition Rating risk rating 5 Could result in more than 50 fatalities
4 Could result in 10 - 49 fatalities
Fatalities 3 Could result in 5 - 9 fatalities 3
2 Could result in 1 - 4 fatalities
1 Not likely to result in fatalities Although no fatalities were reported in Cape Breton following the rainfall events caused by Hurricane Matthew, roads were damaged and could have caused fatal car Supplemental information accidents. The wind caused trees to fall and although unlikely, that could be a cause of fatality. Furthermore, the mayor of CBRM, Cecil Clarke, reported that thousands of (optional) homes were flooded with water (and sewer in some cases) in an interview with the CBC. Residential flooding could be a risk to life for persons with limited mobility. The proximity of many houses to harbours and the coastline, as well as the low-lying areas throughout the major watersheds means many residents are vulnerable to flooding - flooding throughout the watershed could impair rescue/response access for the fire station first responders, in turn causing a secondary risk to health/life. Glace Bay Hospital as well as Seaview Manor Home For Special Care could be considered to house the most vulnerable residents, and both those establishments are very close to the coastline. The Cape Breton Regional Hospital is just downstream of the city Reservoir and would be at risk if there is a breach.
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Injuries, illness and/or psychological disablements cannot be addressed by local, regional, or provincial/territorial 5 healthcare resources; federal support or intervention is required Injuries, illnesses and/or psychological disablements cannot be addressed by local or regional healthcare resources; 4 provincial/territorial healthcare support or intervention is required. Injuries, illnesses and/or psychological disablements cannot be addressed by local or regional healthcare resources additional Injuries 3 2 healthcare support or intervention is required from other regions, and supplementary support could be required from the province/territory Injuries, illnesses and/or psychological disablements cannot be addressed by local resources through local facilities; healthcare support 2 is required from other areas such as an adjacent area(ies)/municipality(ies) within the region Any injuries, illnesses, and/or psychological disablements can be addressed by local resources through local facilities; available resources 1 can meet the demand for care Supplemental information It is probable that during and after flooding events like the ones in 2016, some residents with injuries, illnesses and/or psychological disablements would be treated at Cape (optional) Breton Regional Hospital in Sydney. It is also possible in a disaster situation that resources from the Province would be deployed to CBRM to assist in the recovery efforts.
Risk Assigned Definition Rating risk rating 5 > 15% of total local population
Percentage 4 10 - 14.9% of total local population of 3 5 - 9.9% of total local population 3 displaced individuals 2 2 - 4.9% of total local population 1 0 - 1.9% of total local population Displacement 5 > 26 weeks (6 months) 4 4 weeks - 26 weeks (6 months) Duration of 3 1 week - 4 weeks 3 displacement 2 72 hours - 168 hours (1 week) 1 Less than 72 hours Although no precise information validating these risk ratings is available at this time for each of the Watersheds, the assumption is made that flooding events of the magnitude Supplemental information of the 2016 events would displace a similar percentage of individuals and for a similar duration as was the case in the Wash Brook Watershed (Sydney). Some residents could (optional) be permanently displaced if homes are damaged beyond repair.
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B) Environmental impacts
> 75% of flora or fauna impacted or 1 or more ecosystems significantly impaired; Air quality has significantly deteriorated; Water quality is 5 significantly lower than normal or water level is > 3 meters above highest natural level; Soil quality or quantity is significantly lower (i.e., significant soil loss, evidence of lethal soil contamination) than normal; > 15% of local area is affected 40 - 74.9% of flora or fauna impacted or 1 or more ecosystems considerably impaired; Air quality has considerably deteriorated; Water 4 quality is considerably lower than normal or water level is 2 - 2.9 meters above highest natural level; Soil quality or quantity is moderately 3 lower than normal; 10 - 14.9% of local area is affected 10 - 39.9% of flora or fauna impacted or 1 1 or more ecosystems moderately impaired; Air quality has moderately deteriorated; Water quality is 3 moderately lower than normal or water level is 1 - 2 meters above highest natural level; Soil quality is moderately lower than normal; 6 - 9.9 % of area affected
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< 10 % of flora or fauna impacted or little or no impact to any ecosystems; Little to no impact to air quality and/or soil quality or quantity; 2 Water quality is slightly lower than normal, or water level is less than 0.9 meters above highest natural level and increased for less than 24 hours; 3 ‐ 5.9 % of local area is affected Little to no impact to flora or fauna, any ecosystems, air quality, water quality or quantity, or to soil quality or quantity; 0 ‐ 2.9 % of local 1 area is affected Sewage backup could cause the water quality to be impaired. Risks of contamination of the environment exist due to flood impacts of home or commercial fuel tanks (for example - fueling station at the North Sydney Fire Station). Each of the watersheds under consideration include a natural watercourse system, which are directly impacted by the extreme rainfall/flood events. Supplemental information (optional)
C) Local economic impacts
Risk Assigned Definition Rating risk rating 5 > 15 % of local economy impacted
4 10 ‐ 14.9 % of local economy impacted
3 6 ‐ 9.9 % of local economy impacted 5
2 3 ‐ 5.9 % of local economy impacted
1 0 ‐ 2.9 % of local economy impacted Economy practically stalled during and following an event like the rainfalls caused by Hurricane Matthew. Damage to residential dwellings and commercial properties puts further and lasting stress on the local economy.
Supplemental information (optional)
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D) Local infrastructure impacts
Risk Assigned Definition Rating risk rating Local activity stopped for more than 72 hours; > 20% of local population affected; lost access to local area and/or delivery of crucial 5 service or product; or having an international level impact Local activity stopped for 48 - 71 hours; 10 - 19.9% of local population affected; significantly reduced access to local area and/or delivery 4 of crucial service or product; or having a national level impact Local activity stopped for 25 - 47 hours; 5 - 9.9% of local population affected; moderately reduced access to local area and/or delivery of crucial Transportation 3 4 service or product; or having a provincial/territorial level impact Local activity stopped for 13 - 24 hours; 2 - 4.9% of local population affected; minor reduction in access to local area and/or delivery of crucial 2 service or product; or having a regional level impact Local activity stopped for 0 - 12 hours; 0 - 1.9% of local population affected; little to no reduction in access to local area and/or delivery of 1 crucial service or product Time for water to recede and access to certain areas affected by damaged infrastructure could be greater than 24 hours. Road washout can significantly reduce access to local areas. (Example, washout of Cadegan and Renwick Brook Culverts in 2016, Kings Road culvert washout in 2016).
Supplemental information (optional)
5 Duration of impacts > 72 hours; > 20% of local population without service or product; or having an international level impact 4 Duration of impact 48 - 71 hours; 10 - 19.9% of local population without service or product; or having a national impact
Energy and Utilities 3 Duration of impact 25 - 47 hours; 5 - 9.9% of local population without service or product; or having a provincial/territorial level impact 3 2 Duration of impact 13 - 24 hours; 2 - 4.9% of local population without service or product; or having a regional level impact Local activity stopped for 0 - 12 hours; 0 - 1.9% of local population affected; little to no reduction in access to local area and/or delivery of 1 crucial service or product
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During the rainfall events of 2016, most of the customers had power back within 24-48 h. Hurricaine Matthew was considered to have had a provincial/territorial impact, and also required some Federal support. Although statistics are unavailable, it is plausible that more that 10 % of the residents of the watershed community were impacted.
Supplemental information (optional)
5 Service unavailable for > 72 hours; > 20 % of local population without service; or having an international level impact
Information 4 Service unavailable for 48 ‐ 71 hours; 10 ‐ 19.9 % of local population without service; or having a national level impact and 3 Service unavailable for 25 ‐ 47 hours; 5 ‐ 9.9 % of local population without service; or having a provincial/territorial level impact 3 Communications Technology 2 Service unavailable for 13 ‐ 24 hours; 2 ‐ 4.9 % of local population without service; or having a regional level impact 1 Service unavailable for 0 ‐ 12 hours; 0 ‐ 1.9 % of local population without service The assumption is made that Information and Communication Technology was affected similarly to Energy and Utilities (power outages)
Supplemental information (optional)
Inability to access potable water, food, sanitation services, or healthcare services for > 72 hours; non‐essential services 5 cancelled; > 20 % of local population impacted; or having an international level impact Inability to access potable water, food, sanitation services, or healthcare services for 48‐72 hours; major delays for nonessential 4 services; 10 ‐ 19.9 % of local population impacted; or having a national level impact Inability to access potable water, food, sanitation services, or healthcare services for 25‐48 hours; moderate delays for nonessential Health, Food, and Water 3 3 services; 5 ‐ 9.9 % of local population impacted; or having a provincial/territorial level impact Inability to access potable water, food, sanitation services, or healthcare services for 13‐24 hours; minor delays for nonessential; 2 2 ‐ 4.9 % of local population impacted; or having a regional level impact Inability to access potable water, food, sanitation services, or healthcare services for 0‐12 hours; 0 ‐ 1.9 % of local population 1 impacted
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No precise information available but the assumption is made that access to health, food and water was similar to that during the 2016 event. The assumption is made that access to health, food and water services are related to transportation route and emergency services access.
Supplemental information (optional)
> 20 % of local population impacted; loss of intelligence or defence assets or systems for > 72 hours; or having an international level 5 impact 10 ‐ 19.9 % of local population impacted; loss of intelligence or defence assets or systems for 48 – 71 hours; or having a national level 4 impact 5 ‐ 9.9 % of local population impacted; loss of intelligence or defence assets or systems for 25 – 47 hours; or having a Safety and Security 3 2 provincial/territorial level impact 2 ‐ 4.9 % of local population impacted; loss of intelligence or defence assets or systems for 13 – 24 hours; or having a regional level 2 impact
1 0 ‐ 1.9 % of local population impacted; loss of intelligence or defence assets or systems for 0 – 12 hours
Limited Police and First responder services/response times due to road closures or washout, having a regional level impact.
Supplemental information (optional)
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E) Public sensitivity impacts
Risk Assigned Definition Rating risk rating Sustained, long term loss in reputation/public perception of public institutions and/or sustained, long term loss of trust and confidence in 5 public institutions; or having an international level impact Significant loss in reputation/public perception of public institutions and/or significant loss of trust and confidence in public institutions; 4 significant resistance; or having a national level impact Some loss in reputation/public perception of public institutions and/or some loss of trust and confidence in public institutions; escalating 3 3 resistance
2 Isolated/minor, recoverable set‐back in reputation, public perception, trust, and/or confidence of public institutions
1 No impact on reputation, public perception, trust, and/or confidence of public institutions
High degree of public sensitivity following Hurricane Matthew. Flooding occurrences are ongoing and set to increase in frequency and intensity with climate change. The presence of visibly deteriorated and/or undersized culverts which can have a direct impact on the flooding can raise questions by the public.
Supplemental information (optional)
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Confidence Assessment
Based on the table below, indicate the level of confidence regarding the information entered in the risk assessment information template in the “Confidence Level Assigned” column. Confidence levels are language‐based and range from A to E (A=most confident to E=least confident).
Confidence Level Definition Confidence Level Assigned
Very high degree of confidence Risk assessment used to inform the risk assessment information template was evidence‐based on a thorough knowledge of the natural hazard risk event; leveraged a significant quantity of high‐quality data that was quantitative and qualitative in nature; A leveraged a wide variety of data and information including from historical records, geospatial and other information sources; and the risk assessment and analysis processes were completed by a multidisciplinary team with subject matter experts (i.e., a wide array of experts and knowledgeable individuals on the specific natural hazard and its consequences) Assessment of impacts considered a significant number of existing/known mitigation measures
High degree of confidence Risk assessment used to inform the risk assessment information template was evidence‐based on a thorough knowledge of the natural hazard risk event; leveraged a significant quantity of data that was quantitative and qualitative in nature; leveraged a wide B variety of data and information including from historical records, geospatial and other information sources; and the risk assessment and analysis processes were completed by a multidisciplinary team with some subject matter expertise (i.e., a wide array of experts and knowledgeable individuals on the specific natural hazard and its consequences) Assessment of impacts considered a significant number of potential mitigation measures
Page 18 of 20 UNCLASSIFIED National Disaster Mitigation Program Risk Assessment Information Template Moderate confidence Risk assessment used to inform the risk assessment information template was moderately evidence‐based from a considerable amount of knowledge of the natural hazard risk event; leveraged a considerable quantity of data that was quantitative and/or qualitative in nature; leveraged a considerable amount of data and information including from historical records, geospatial and C other information sources; and the risk assessment and analysis processes were completed by a moderately sized multidisciplinary team, incorporating some subject matter experts (i.e., a wide array of experts and knowledgeable individuals on the specific natural hazard and its consequences) Assessment of impacts considered a large number of potential mitigation measures
Low confidence Risk assessment used to inform the risk assessment information template was based on a relatively small amount of knowledge of the natural hazard risk event; leveraged a relatively small quantity of quantitative and/or qualitative data that was largely historical in nature; may have leveraged some geospatial information or information from other sources (i.e., databases, key risk and D C resilience methodologies); and the risk assessment and analysis processes were completed by a small team that may or may not have incorporated subject matter experts (i.e., did not include a wide array of experts and knowledgeable individuals on the specific natural hazard and its consequences). Assessment of impacts considered a relatively small number of potential mitigation measures
Very low confidence Risk assessment used to inform the risk assessment information template was not evidence‐based; leveraged a small quantity of information and/or data relating to the natural risk hazard and risk event; primary qualitative information used with little to no E quantitative data or information; and the risk assessment and analysis processes were completed by an individual or small group of individuals little subject matter expertise (i.e., did not include a wide array of experts and knowledgeable individuals on the specific natural hazard and its consequences). Assessment of impacts did not consider existing or potential mitigation measures
Rationale for level of confidence
The process was completed using a collaborative approach, involving an integrated team of consultants, subject matter experts, departmental staff, management, engineering, planning, emergency response and operations personnel. Project workshops brought together key stakeholders to hear Provide the rationale for the selected varying opinions, information, and perspective to develop a collaborative understanding of each site, considering a variety of impacts. The process was confidence level, including any references or successful in gathering a unified consensus on the sites of highest priority within the municipality to focus on more delailed assessment and sources to support the level assigned. development of mitigation measures. The flooding events of October 2016 were widely covered by the media and information regarding their impacts on the area is publicly available online. Future climate change was considered, identifying the projected increase in the intensity and the frequency or rainfall events , which could trigger flood events. The process leveraged a considerable amount of publicly available GIS based Asset Management data, reviewing multiple databases as well as historical records. The compilation of information for the site provided valuable information for use in multiple mitigation planning and engineering works. Multiple mitigation strategies for various time horizons were considered.
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Key Information Sources
Supplementary information: Refer to following report for additional supplementary information:
- Main Project Report entitled ``Cape Breton Regional Municipality National Disaster Mitigation Program (NDMP) Flood Risk Identify all supporting documentation and information sources for Assessments`` qualitative and quantitative data used to identify risk events, develop the risk event description, and assess impacts and likelihood. This Please refer to ``References`` Section of the Main and Site Reports for key information sources. ensures credibility and validity of risk information presented as well as enables referencing back to decision points at any point in time.
Clearly identify unclassified and classified information.
Description of the risk analysis team
The risk analysis team included a wide array of technical experts, municipal management and operations staff, including: - Cape Breton Regional Municipality (CBRM) - Client; Engineering, Planning, Operations, & Emergency Management Staff. A stakeholder risk assessment workshop was held as part of the project to collect information, feedback and develop a unified understanding of risk and impacts at each watershed. - WSP Canada Inc. - Lead consultant; Engineers, Land-Use Planners, Technical Advisors List and describe the type and level of experience of each - ClimAction Services - Subconsultant; Subject Matter Experts - Climate Change Meteorologists individual who was involved with the completion of the risk assessment and risk analysis used to inform the information contained within this risk assessment information template. Further information on the Team and project methodology is included in the main project report.
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