Thompson Creek Flood Study Report - City of Peterborough

THOMPSON CREEK 

DETAILED FLOOD REDUCTION STUDY 

PREPARED FOR: 

CITY OF PETERBOROUGH 

JUNE 2007

City of Peterborough June 14 ,2007 

Engineering and Construction Division 

14-06605-01-W01 

City Hall, 500 George Street North 

Peterborough, Ontario 

K9H 3R9 

Attention: 

Mr. Dan Ward 

Flood Reduction Program Manager 

Dear Mr. Ward, 

Re: Draft Final Report – Thompson Creek Detailed Flood Reduction Study 

We are pleased to submit five copies of our draft final report for the Thompson Creek Detailed Flood Reduction 

Study. It provides a complete description of the work undertaken to identify the degree of flood vulnerability 

and potential remedial measures for flood problems in the Thompson Creek study area. It follows the format of 

an environmental study report including discussion of public input to the study process. In this version, we have 

incorporated comments from City staff, the Technical Advisory Committee and from the 2 nd Public Information 

Centre. 

We trust this information is satisfactory but should you have any questions or require anything else from us, 

please contact the undersigned. We understand this document will be released in the near future for public 

review and we look forward to any comments resulting from that process. 

Yours Very Truly, 

MARSHALL MACKLIN MONAGHAN LIMITED 

Robert Bishop, M.Sc., P.Eng. 

Vice President, Water Resources

Thompson Creek Detailed Flood Reduction Study 

City of Peterborough 

ACKNOWLEDGEMENTS 

We wish to acknowledge the contributions of the following to the successful 

completion of the Thompson Creek Detailed Flood Reduction Study. 

Ms. Ann Farquarson, Chair, Citizens Advisory Panel (CAP) 

Mr. David Buritt, ORCA 

Mr. David Ness, Trent Severn Waterway 

Mr. Peter Lafleur, Trent University 

Mr. Dan Ward, City of Peterborough 

Mr. David Bonsall, City of Peterborough 

Mr. Chris Lang, City of Peterborough 

Other members of the Technical Advisory Committee and the CAP not specifically 

named above. 

Members of the public who attended the Public Information Centres and provided 

valuable comments and information. 

14-06605-01-W01 

City of Peterborough



Letter of Transmittal 

ACKNOWLEDGEMENTS 

TABLE OF CONTENTS 

1.0 INTRODUCTION...............................................................................................................1 

1.1 BACKGROUND .............................................................................................................1 

1.2 CLASS ENVIRONMENTAL ASSESSMENT PROCESS .........................................................3 

2.0 PHASE 1 – PROBLEM OR OPPORTUNITY.................................................................8 

2.1 DEFINITION OF STUDY AREA .......................................................................................8 

2.2 IDENTIFICATION OF THE PROBLEM ...............................................................................8 

2.3 PROBLEM STATEMENT.................................................................................................8 

3.0 PHASE 2 – EXISTING ENVIRONMENTAL CONDITIONS.....................................10 

3.1 GENERAL...................................................................................................................10 

3.2 SUMMARY OF AVAILABLE INFORMATION ..................................................................10 

3.2.1 Previous Studies...........................................................................................10 

3.2.2 Available Data and Data Gaps....................................................................13 

3.3 NATURAL ENVIRONMENTAL RESOURCES...................................................................15 

3.3.1 Fish Community and Fish Habitat...............................................................15 

3.3.2 Terrestrial Features: Wetlands, Vegetation and Wildlife............................18 

3.3.3 Fluvial Geomorphology...............................................................................23 

3.3.4 Water Quantity Characteristics ...................................................................28 

3.3.5 Water Quality Characteristics .....................................................................29 

3.3.6 Surficial Soils/Geology/Hydrogeology ........................................................29 

3.4 SOCIO-ECONOMIC ENVIRONMENT .............................................................................30 

3.4.1 Existing Land Use........................................................................................30 

3.4.2 Future Land Use ..........................................................................................34 

3.5 SUMMARY OF EXISTING ENVIRONMENTAL CONDITIONS ............................................34 

4.0 PHASE 2 – EXISTING CONDITIONS: FLOOD VULNERABILITY......................37 

4.1 GENERAL...................................................................................................................37 

4.2 SUMMARY OF AVAILABLE FLOOD RELATED INFORMATION .......................................37 

4.2.1 Flood Reduction Master Plan......................................................................37 

4.2.2 Existing Flood Plain Mapping.....................................................................39 

4.2.3 Flow Monitoring ..........................................................................................39 

4.3 EXISTING DRAINAGE/STORMWATER MANAGEMENT SYSTEM .....................................43 

4.3.1 Thompson Creek Drainage Area .................................................................43 

4.3.2 Local Drainage To Otonabee River.............................................................44 

4.4 MODELLING CHARACTERISTICS OF MAJOR/MINOR SYSTEMS ....................................45 

4.4.1 OTTHYMO Modelling of Thompson Creek Drainage Area ........................45 

4.4.2 HEC-RAS Modelling of Thompson Creek....................................................49 

4.4.3 OTTSWMM Modelling of Local Drainage Systems.....................................50 

4.5 SIMULATION OF FLOOD VULNERABILITY DESIGN EVENTS.........................................54 

4.5.1 Definition of Design Rainfalls .....................................................................54 

4.5.2 Results of Thompson Creek Watercourse Simulations ................................58 

4.5.3 Results of Local Drainage Systems Simulations..........................................65 

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4.6 MAPPING OF FLOOD VULNERABLE LOCATIONS ...................................................73 

4.6.1 Results for Thompson Creek Watercourse...................................................73 

4.6.2 Results for Local Drainage Systems ............................................................75 

4.7 FLOOD DAMAGE ESTIMATION .............................................................................88 

4.7.1 Results for Thompson Creek Watercourse...................................................89 

4.7.2 Results for Local Drainage Systems ............................................................89 

4.8 SUMMARY OF FLOOD VULNERABILITY ................................................................91 

5.0 PHASE 2 – EVALUATION OF FLOOD PROTECTION OPTIONS.........................93 

5.1 CORNER OF SCOLLARD DRIVE (NEAR FRANCIS STEWART RD).............................93 

5.2 NW CORNER ELDON COURT AND FRANCIS STEWART ROAD................................95 

5.3 FRANMOR DRIVE,CHAPEL DRIVE, ABBEY LANE AREA ...................................95 

5.4 ARMOUR ROAD SOUTH OF MOIR STREET.............................................................96 

5.5 FLOOD PROTECTION RECOMMENDATIONS ....................................................97 

LIST OF APPENDICES 

APPENDIX A.......................................................................................TERMS OF REFERENCE 

APPENDIX B...................................................DOCUMENTATION OF PUBLIC CONSULTATION 

APPENDIX C...........................................PHOTOGRAPHS OF THOMPSON CREEK WATERSHED 

APPENDIX D...................................................................................FISHERIES INFORMATION 

APPENDIX E............................................................ TERRESTRIAL FEATURES INFORMATION 

APPENDIX F .................................................................GEOMORPHOLOGICAL INFORMATION 

APPENDIX G ...........................................................FLOW &RAINFALL MONITORING DATA 

APPENDIX H ........................................................... OTTHYMO MODEL DOCUMENTATION 

APPENDIX I ...............................................................HEC-RAS MODEL DOCUMENTATION 

APPENDIX J ........................................................... OTTSWMM MODEL DOCUMENTATION 

APPENDIX K ....................................................................DESIGN RAINFALL INFORMATION 

LIST OF DRAWINGS 

DRAWING NO. ........................................................................................................ LOCATION 

SS-1 

FV-1 

FV-2A, 

B & C 

FV-3 

STORM SEWER SYSTEM –THOMPSON CREEK STUDY AREA........................POCKET 

THOMPSON CRK FLOOD LINES – 100 YEAR,JULY 2004 & 

TIMMINS STORMS.......................................................................................POCKET 

THOMPSON CRK FLOOD LINES –VOLUME BASED STORMS ....................... POCKET 

THOMPSON CRK FLOOD LINES –THOMPSON CREEK DAM RELEASES ....... POCKET 

SF-1 EXTENT OF FLOODING –SCOLLARD DR.&ELDON CRT.– 

100 YEAR &JULY 2004 STORMS ......................................................... POCKET 

SF-2 EXTENT OF FLOODING –FRANMOR DR.&MOIR ST.AREA – 

SF-3 

100 YEAR &JULY 2004 STORMS ......................................................... POCKET 

EXTENT OF FLOODING –SCOLLARD DR.&ELDON CRT.– 

40 MM &60 MM STORMS ...................................................................... POCKET 

SF-4 EXTENT OF FLOODING –FRANMOR DR.&MOIR ST.AREA – 

40 MM &60 MM STORMS ......................................................................... POCKET 

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LIST OF FIGURES 

FIGURE NO. .................................................................................................. FOLLOWS PAGE 

1.1 STUDY AREA LOCATION PLAN ....................................................................................2 

1.2 SCHEMATIC SHOWING CLASS EA PROCESS .................................................................4 

2.1 DEFINITION OF STUDY AREA .......................................................................................9 

3.3.1 FISH HABITAT SAMPLING LOCATIONS –THOMPSON CREEK ......................................15 

3.3.2 ELC MAPPING FOR THOMPSON CREEK RIPARIAN CORRIDOR ....................................18 

3.3.3 RARE VASCULAR PLANTS -THOMPSON CREEK ..........................................................19 

3.3.4 BIRD HABITATS - THOMPSON CREEK ........................................................................19 

3.3.5 GEOMORPHOLOGY SURVEY LOCATIONS -THOMPSON CREEK....................................23 

3.3.6 SURFICIAL SOILS OF THOMPSON CREEK STUDY AREA...............................................30 

3.4.1 LAND USE WITHIN STUDY AREA ACCORDING TO O.P.SCHEDULE A..........................30 

3.4.2 CURRENT LAND USE WITHIN STUDY AREA...............................................................30 

3.4.3 FUTURE LAND USE WITHIN AUBURN NORTH SECONDARY PLAN AREA .....................34 

4.2.1 LOCATION OF TEMPORARY FLOW GAUGES................................................................41 

4.2.2 TYPICAL PERIOD OF RECORD FROM GAUGE AT MOUTH OF THOMPSON CREEK .........42 

4.4.1 OTTHYMO MODEL SUBCATCHMENTS –EXISTING CONDITIONS .................................45 

4.4.2 OTTHYMO MODEL SUBCATCHMENTS –FUTURE CONDITIONS ....................................46 

4.4.3 OTTSWMM VERIFICATION –JUNE 1, 2006 EVENT .................................................51 

4.5.1 ESTIMATED RAINFALL FOR JULY 2004 STORM OVER THOMPSON CREEK...................55 

4.5.2 RAINFALL MEASUREMENTS NEAR STUDY AREA FOR JULY 2004 STORM ..................56 

4.5.3 HYETOGRAPH FOR JULY 2004 STORM OVER THOMPSON CREEK................................56 

4.5.4 HYETOGRAPHS FOR SELECTED RAINFALL EVENTS ....................................................57 

5.1 FLOOD REDUCTION CONCEPTS –SCOLLARD DRIVE .................................................93 

5.2 FLOOD REDUCTION CONCEPTS –ELDON COURT ......................................................95 

5.3 FLOOD REDUCTION CONCEPTS –FRANMOR DRIVE AREA ........................................96 

5.4 FLOOD REDUCTION CONCEPTS –WHITAKER AND ARMOUR RD.AREA ....................96 

5.5 FLOOD REDUCTION CONCEPTS –MOIR STREET AREA .............................................97 

PHOTO NO. 

LIST OF PHOTGRAPHS 

PAGE 

3.3.1 GEOMORPHOLOGICAL OBSERVATIONS –THOMPSON CREEK......................................25 






4.2.1 TEMPORARY FLOW GAUGE –MOUTH OF THOMPSON CREEK .....................................40 

4.6.1 FLOOD SUSCEPTIBLE AREA –SCOLLARD DRIVE .......................................................77 

4.6.2 FLOOD SUSCEPTIBLE AREA –ELDON COURT ............................................................79 

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LIST OF TABLES 

TABLE NO...................................................................................................................... PAGE 

1.1 TECHNICAL ADVISORY COMMITTEE MEMBERS ...........................................................7 

3.2.1 LIST OF PREVIOUS STUDIES .......................................................................................10 

3.3.1 LIST OF BREEDING BIRDS IN THOMPSON CREEK STUDY AREA & 

CONSERVATION STATUS ........................................................................................21 

3.3.2 NUMERICAL SUMMARY OF BREEDING SPECIES OF CONSERVATION INTEREST 

BY HABITAT TYPE..................................................................................................23 

3.3.3 GEOMORPHIC CHARACTERISTICS OF THOMPSON CREEK ...........................................24 

3.3.4 SURFACE WATER QUALITY DATA IN THOMPSON CREEK WATERSHED ......................29 

3.4.1 APPROX.DISTRIBUTION (%) OF LAND USES IN THOMPSON CREEK STUDY AREA .......34 

4.2.1 INFORMATION USED TO DEVELOP RATING CURVES ..................................................40 

4.4.1 OTTHYMO MODEL PARAMETERS –EXISTING CONDITIONS ....................................46 

4.4.2 OTTHYMO MODEL PARAMETERS – FUTURE CONDITIONS .......................................47 

4.4.3 COMPARISON OF OBSERVED AND SIMULATED FLOWS FOR JUNE 1, 2006 EVENT ......49 

4.4.4 COMPARISON OF OBSERVED AND SIMULATED PEAK FLOWS OTTSWMM ................52 

4.5.1 TOTAL RAINFALL VOLUMES FOR 1 HOUR AND 6HOUR STORMS ...............................58 

4.5.2 PEAK FLOWS -THOMPSON CREEK -6HOUR AES RETURN PERIOD STORMS ............59 

4.5.3 PEAK FLOWS -THOMPSON CREEK -1HOUR AES RETURN PERIOD STORMS ............59 

4.5.4 WATER LEVELS -THOMPSON CREEK -1HOUR AES RETURN PERIOD STORMS ........60 

4.5.5 PEAK FLOWS -THOMPSON CREEK -1HOUR AES VOLUME BASED STORMS ............61 

4.5.6 PEAK FLOWS -THOMPSON CREEK – 193 MM (TIMMINS)STORM ..............................61 

4.5.7 WATER LEVELS -THOMPSON CREEK – 120 MM STORM AND TIMMINS STORM .........62 

4.5.8 PEAK FLOWS -THOMPSON CREEK –JULY 2004 STORM ...........................................63 

4.5.9 WATER LEVELS -THOMPSON CREEK –JULY 2004 STORM .......................................63 

4.5.10 PEAK FLOWS -THOMPSON CREEK FOR RELEASES FROM THOMPSON BAY DAM ........65 

4.5.11 WATER LEVELS -THOMPSON CREEK FOR RELEASES FROM THOMPSON BAY DAM ....66 

4.5.12 RETURN PERIOD FLOWS –LOCAL DRAINAGE SYSTEMS -THOMPSON CREEK ............67 

4.5.13 RETURN PERIOD FLOWS –LOCAL DRAINAGE SYSTEMS –OTONABEE RIVER ............68 

4.5.14 VOLUME BASED FLOWS –LOCAL DRAINAGE SYSTEMS -THOMPSON CREEK ............71 

4.5.15 VOLUME BASED FLOWS –LOCAL DRAINAGE SYSTEMS –OTONABEE RIVER ............72 

4.6.1 WATER DEPTH –SCOLLARD DR.&ELDON CRT.–1 IN 2 TO 1 IN 100 YEAR STORM ..77 

4.6.2 WATER DEPTH –FRANMOR DRIVE AREA –1 IN 2 TO 1 IN 100 YEAR STORM ............80 

4.6.3 WATER DEPTH –MOIR STREET AREA –1 IN 2 TO 1 IN 100 YEAR STORM .................82 

4.6.4 WATER DEPTH –SCOLLARD DR.&ELDON CRT.– VOLUME BASED EVENTS ............83 

4.6.5 WATER DEPTH –FRANMOR DRIVE AREA – VOLUME BASED EVENTS .......................85 

4.6.6 WATER DEPTH –MOIR STREET AREA – VOLUME BASED EVENTS ............................86 

4.6.7 WATER DEPTH –LOCAL SYSTEMS –JULY 2004 STORM –THOMPSON CREEK AREA ..87 

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1.0 INTRODUCTION 

1.1 BACKGROUND 

In July 2004, the City of Peterborough experienced severe flooding as a result of an 

extreme rainfall event which centred on the downtown area. The recorded rainfall 

showed a total of 250 mm spread over 40 hours. However, 90% of the total 

precipitation (220mm) fell within an uninterrupted period of only 9 hours from 22:10 

on the 14 th to 08:10 on the 15 th of July. Flood damage was reportedly in excess of $100 

million in direct physical damages to private and public property. In addition, the City 

suffered indirect damages such as disruption in residential living conditions, loss of 

business, and loss of wages or income. 

In the aftermath of the July 2004 storm, it was recognized that measures would be 

needed to upgrade the level of flood protection afforded to the citizen’s of 

Peterborough. The first step was to complete a city-wide Flood Reduction Master Plan 

which examined the problem in a comprehensive way and recommended a series of 

actions to achieve higher levels of protection over the long term. A key 

recommendation was the need to complete a series of detailed Flood Reduction Studies 

covering all the watercourses within the City’s boundaries. These studies are designed 

to: 

• Identify the severity and frequency of flooding and associated damages 

• Identify and assess alternative, cost-effective solutions which can be 

implemented to alleviate existing problems and prevent problems from future 

development 

• Assess and rank solutions in terms of flood reduction, erosion and water quality 

effectiveness. 

The Thompson Creek study area is one of seven areas within the City which is 

currently/or soon to be the subject of a detailed Flood Reduction Study. The area is 

located in the north east sector of the City and covers about 200 hectares of land 

between the Trent Canal and the Otonabee River (see Figure 1.1 for the general 

location). It consists of two parts: the Thompson Creek watershed itself and several 

local drainage areas to the south which outlet directly to the Otonabee River. The 

headwaters of Thompson Creek are severed by the Canal and inflows from the Canal 

are controlled by a dam with stop logs. There is currently a limited amount of 

development within the watershed but significant areas on either side of the creek are 

planned to be developed. These have been the subject of previous water management 

studies including a Master Drainage Plan (MDP), a Class Environmental Assessment 

(Class EA) for a central SWM facility and several stormwater management studies. 

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General 

Location of 

Study Area 

Figure 1.1: Study Area Location Plan 




These have examined the constraints which the existing drainage systems place on 

future development and have proposed conceptual stormwater management plans to 

address these issues. In each case, these recommendations will address future 

development concerns but not necessarily existing concerns. The present study provides 

a watershed-wide examination of the existing and potential problems to develop an 

integrated plan for flood damage reduction. 

The study was designed to potentially address two types of flooding situations which 

may have occurred in the past or may occur in the future. The first of these is water 

course related, i.e. inadequacies in the capacity of the creek channel or culvert crossings 

which cause flooding to adjacent areas. The second type is more localized flooding 

resulting from inadequacies in the storm sewer systems or local roadways/ditches, i.e. 

lack of capacity for relatively frequent events. Both types of flooding were investigated 

during the study and appropriate solutions are recommended where appropriate. 

As required by the Terms of Reference (see Appendix A), the study was conducted 

within the framework of a Municipal Class Environmental Assessment. This was 

appropriate not only because it provides a basis for approvals for any specific 

recommended projects but also because it addresses the problem in a multi-objective, 

ecosystem based way. This provides opportunities to not only avoid potential 

environmental impacts but to develop projects which integrate environmental 

restoration and enhancement. Examples could include the use of “natural channel 

design” where channel improvements are recommended, the provision of fish passage 

where culvert improvements/enlargements are required and use of artificial wetlands to 

provide runoff storage. 

Marshall Macklin Monaghan Ltd was authorized by the City of Peterborough on 

March 21, 2006 to complete a Detailed Flood Reduction Study for Thompson Creek 

based upon the Terms of Reference contained in Appendix A. This document describes 

the investigations completed to assess flood vulnerability within the Thompson Creek 

study area and the recommended measures required to improve the level of flood 

protection afforded to the citizen’s of the area. As noted, the project was based upon 

detailed technical studies and consultation with the public, relevant agencies and other 

stakeholders through the Class Environmental Assessment process. 

1.2 CLASS ENVIRONMENTAL ASSESSMENT PROCESS 

This report has been prepared within the framework of the Class Environmental 

Assessment according to the Municipal Engineers Association (MEA) Municipal Class 

Environmental Assessment (June 2000). The Class EA document has been accepted 

and approved under the Environmental Assessment Act. The Municipal Class EA 

process is generally undertaken in five phases (see Figure 1.2) as follows: 




Figure1.2: Schematic Showing Municipal Class EA Process 




• Phase 1 – identification of the problem or opportunity 

• Phase 2 – identification of alternative solutions 

• Phase 3 – preparation of alternative design concepts for preferred solution 

• Phase 4 – preparation of the Environmental Study Report or Master Plan Report 

• Phase 5 – implementation. 

Since this study was intended to develop an overall plan for flood damage reduction, it 

has been carried out in compliance with the Master Plan component of the Class EA as 

described in Sections A2.7 and Appendix 4 of the Class EA document. As required by 

that document, it fulfils Phases 1 and 2 of the Class EA process. For individual projects 

within the Plan which are identified as Schedule B projects, this document will 

generally fulfil Phase 1 and 2 EA documentation requirements for them. For larger, 

more complex projects which are identified as Schedule C projects, additional 

documentation will be required to fulfil Phases 3 through 5. 

The Master Plan process involves a minimum of two mandatory points of contact with 

the directly involved public and relevant review agencies to ensure they are aware of 

the project and that their concerns are addressed. The process requires that a project 

file be prepared and submitted for review by the public at the end of Phase 2. If 

outstanding concerns do not emerge from this review, the municipality may proceed to 

implementation (subject to any additional EA requirements). If however the review 

process raises a concern that cannot be resolved, the opportunity to request a Part II 

order to “bump up” of the Class EA to an Individual EA is available at the point when 

individual projects identified within the Plan are implemented. It is not possible to 

request a Part II order for a Master Plan itself. 

As part of the current study, the following EA activities were completed: 

Issuance of Notice of Commencement 

A Notice of Commencement was issued in the local media and by direct mailing to 

appropriate agencies, NGOs and other potential stakeholders. Documentation of these 

actions and comments received is provided in Appendix B. 

Public Information Centre No. 1 

Depending on the nature of the project, review agencies and the public may be 

consulted as part of Phase 1. As part of this Class EA, a Public Information 

Centre/Meeting was held at the beginning of the process (June 20, 2006) to introduce 




the public to the study, to request information on flooding issues and solicit their input 

into the problem definition. Documentation is included in Appendix B. 

Public Information Centre No. 2 

Phase 2 of the Class EA process involves a number of steps including identifying all 

reasonable alternative solutions to the problem, documenting the existing environment, 

evaluating the alternative solutions and consulting with appropriate review agencies and 

the public in order to identify the preferred solution. As part of the identification of the 

preferred solution, i.e. the projects, programs and policies that will be included in the 

Thompson Creek Flood Reduction Plan, a second Public Information Centre was held 

to obtain comments from the public on the alternatives considered and the draft plan. 

This occurred on May 23rd, 2007. The information presented at that meeting, the 

comments received and the means by which they were addressed are all documented in 

Appendix B. 

Technical Advisory Committee (TAC) and Public Advisory Committee (PAC) 

Two advisory committees were formed by the City of Peterborough to guide the 

direction of the study and provide input from agency and public stakeholders. The 

Technical Advisory Committee (TAC) consisted of representatives of various 

departments of the City of Peterborough, the County of Peterborough, the Otonabee 

Region Conservation Authority (ORCA), the Ministry of Natural Resources (MNR), 

the Trent Severn Waterway (TSW) and the Department of Fisheries and Oceans Canada 

(DFO). Members are listed in Table 1.1. A Public Advisory Committee (PAC) was 

formed during the completion of the city-wide Flood Master Plan. It was originally 

intended to continue and be common to all of the subsequent detailed flood studies 

including the Thompson Creek study. However, the PAC was disbanded prior to 

completion of this study. 

Issuance of Notice of Completion 

A formal Notice of Study Completion was published in the media in July, 2007. It was 

also sent directly to relevant agencies and all members of the public who had requested 

to be included on the project mailing list. The notice advised of the availability of the 

draft Thompson Creek Detailed Flood Reduction Study Report. The document was 

made available to the public for the statutory 30 day review period. Documentation of 

these actions, comments received by the expiry date of that period and the means by 

which they were addressed is also provided in Appendix B. 

In compliance with the Class EA requirements, this report includes a description of the 

project and its purpose, identification of alternatives, inventory of natural, social and 




economic environments, evaluation of potential environmental effects and appropriate 

mitigation measures, selection of the preferred alternative and documentation of 

consultation with review agencies and the public. 

Table 1.1 

Members of Technical Advisory Committee (TAC) 

Title First Name Last Name Position Company Name 

Mr. Dan Ward Flood Reduction Program City of Peterborough 

Manager 

Mr. David Bonsall Manager, Engineering & City of Peterborough 

Construction, Utility Services 

Department 

Mr. Peter Southall Manager, Public Works Division City of Peterborough 

Mr. Gerry Rye Director, Utility Services City of Peterborough 

Department 

Mr. Malcolm Hunt Director of Planning and City of Peterborough 

Development Services 

Mr. Chris Lang Water Resource Engineer City of Peterborough 

Mr. Chris Bradley Director of Public Works County of Peterborough 

Mr. David Buritt Coordinator, Engineering Otonabee Conservation 

Services and Natural Hazards 

Mr. Chris Strand Habitat Biologist Fisheries and Oceans Canada 

Mr. Wayne Mitchell Realty Manager Parks Canada - Trent Severn 

Waterway 

Ms. Sally Coleman District Planner Ministry of Natural Resources 




2.0 PHASE 1 – PROBLEM OR OPPORTUNITY 

2.1 DEFINITION OF STUDY AREA 

The study area defined for this Class Environmental Assessment consists of the 

Thompson Creek watershed downstream of the Thompson Creek Dam and local 

drainage areas between the southern drainage boundary of Thompson Creek and 

Parkhill Road East which drain directly into the Otonabee River. These areas are 

indicated in Figure 2.1. The Thompson Creek drainage area is approximately 

75 hectares. The total area of the local drainage systems is approximately 125 hectares. 

2.2 IDENTIFICATION OF THE PROBLEM 

There is a long history of flooding in certain areas of the City of Peterborough. The 

natural physiography of the area and the historical evolution of the City have resulted in 

situations where the both the natural and man-made drainage systems are unable to 

safely convey storm runoff during extreme events. The storm of July 2004 was a 

dramatic example of this situation where extensive flood damages occurred throughout 

the City. Flooding occurred for several reasons: i) water courses overflowed and 

flooded adjacent lands; ii) water courses overflowed and spilled flow down the “line of 

least resistance” flooding properties in its path; iii) storm sewers surcharged and flow 

went down available overland flow routes flooding properties in its path, and iv) storm 

and/or sanitary sewers backed up into the basements of properties connected to them. 

2.3 PROBLEM STATEMENT 

The problems identified above may be present to varying degrees within the Thompson 

Creek study area. Defining the magnitude of specific problems was part of the 

investigations completed during the current study. However, the general problem 

statement can be stated as: 

“What are the preferred methods of providing current and future residents of the 

Thompson Creek study area with a satisfactory level of protection from the negative 

impacts of flooding in an environmentally acceptable manner.” 

This problem definition required expansion to identify the specific goals and criteria 

that must be met in order to be considered a valid solution to the problem. This was 

accomplished once the existing conditions within the study area had been characterized 

and a detailed problem list prepared (see Section 4). The criteria for “a satisfactory 

level of protection” were defined as part of the city-wide master plan. The detailed 

evaluation criteria used are described in Section 5 as a prerequisite of the identification 

and evaluation of alternative solutions to the problem. 




City Limits 

City Limits 

Thompson Creek 

Boundary 

Figure 2.1: 

Definition of Study Area 




3.0 PHASE 2 – EXISTING ENVIRONMENTAL 

CONDITIONS 

3.1 GENERAL 

The first step in Phase 2 of the Class EA process was to inventory the existing 

conditions which may affect or conversely may be impacted by alternative solutions to 

the problem. The following sections describe the natural features of Thompson Creek 

and information which was available on the current status of those features. 

Information is presented which contributed to the assessment of alternatives in 

environmental, social and economic terms. 

3.2 SUMMARY OF AVAILABLE INFORMATION 

3.2.1 Previous Studies 

Several studies have been undertaken with respect to the Thompson Creek watershed 

which provided useful background information for the current study. These studies are 

listed in Table 3.2.1 and briefly described below in reverse chronological order. 

Table 3.2.1 

List of Previous Studies 

No. Title Authors Date 

1 

Stormwater Management Report for 

Waverley Heights Subdivision, 

Peterborough, Ontario 

Trow Associates Inc. March 2006 

2 

3 

July 2004 Peterborough Flood Study 

(prepared for Otonabee Region CA & 

the Ministry of Natural Resources) 

City of Peterborough Flood Reduction 

Master Plan 

Kije Sipi Ltd October 2005 

UMA/AECON April 2005 

4 Thompson Creek Management Plan Otonabee Region CA December 2004 

5 

Thompson Creek Central Stormwater 

Management Facility Class EA, 

Environmental Study Report 

TSH Engineers, 

Architects & Planners 

October 2003 

6 

Thompson Creek Master Drainage 

Study 

Totten Sims Hubicki 

Associates 

April 1992 




Stormwater Management Report for Waverley Heights Subdivision, Peterborough, 

Ontario (2006) 

This report describes the proposed stormwater management measures to be 

incorporated into the design of the future phases of the Waverley Heights Subdivision. 

These lands occupy the south east corner of the Thompson Creek watershed. Plans 

include the construction of a stormwater management facility to provided water quality 

control storage, erosion control storage and water quantity storage (for 1 in 2 to 1 in 100 

year storms). 

July 2004 Peterborough Flood Study (2005) 

This report was prepared by Kije Sipi Ltd in October 2005 to analyze the Peterborough 

storm of July 2004. The study analyzed several types of data including rain gauge and 

radar data, synoptic weather maps, historical climate information and various thematic 

maps. The recorded rainfall data was reviewed at 18 rain gauge stations including a 

gauge at Trent University that observed rainfall amounts near the highest zones of 

accumulation. The recorded rainfall showed a total of 250mm spread over 40 hours 

however, 90% of the total precipitation (220mm) fell within an uninterrupted period of 

only 9 hours from 22:10 on the 14 th to 08:10 on the 15 th of July. The average rainfall 

intensity recorded during this 9-hour period was 24.4mm/hr with a peak 30-minute 

intensity of 46mm/hour occurring on 04:10 on the 15 th . 

Data from Environment Canada’s radar located near King City was also calibrated with 

the available rain gauge data to adequately define the areal extent, magnitude, duration 

and frequency of the storm event. The data revealed a concentrated and concentric 

accumulation of rainfall of approximately 15km in diameter that encompassed the 

entire urban area of the City of Peterborough, which received about 90mm to 200mm of 

precipitation over the duration of the entire event. Rainfall accumulations were largest 

in the eastern-most portion of the city while the rural areas to the south, south-west and 

west of the City received lesser amounts of rain ranging between 40mm to 90mm. The 

maximum intensities observed by the radar vary from 40mm/hr to 95mm/hr over the 

City of Peterborough while 10mm/hr to 40mm/hr, in the rural areas within the study 

area. The statistical analysis indicated that all areas within the City of Peterborough 

were subjected to rainfall with a return period over 100 years. 

An analysis of the soil moisture conditions immediately preceding the storm was also 

carried out to assess the potential ground-level impacts of the storm event. The analysis 

indicated that the antecedent soil moisture conditions prior to the July 14-15, 2004 

storm could be characterized as generally normal and average across most of the study 

area for this time of year. 




City of Peterborough Flood Reduction Master Plan (2005) 

This study was prepared by UMA for the City of Peterborough to develop an overall 

work program to reduce flooding in the City in the aftermath of the July 2004 storm. 

This report will be discussed in greater detail in Section 4.2.1 of this document. 

Thompson Creek Management Plan (2004) 

Otonabee Region Conservation Authority prepared this plan in December 2004 in 

partnership with the City of Peterborough to assist Public Works staff with the 

maintenance of urban watercourses without compromising their form, function or 

natural features. 

Detailed inventories of structures and areas of concern are included in the plan with 

recommendations for annual, immediate, short term and long-term maintenance. 

Restoration, recreation and land acquisition opportunities along with the information 

related to policies and regulations are also included in the plan to assist the City staff in 

their implementation of a successful creek management strategy. 

Thompson Creek Central Stormwater Management Facility Class EA, 

Environmental Study Report (2003) 

This report was prepared for the City and ORCA to identify the preferred means of 

providing stormwater management for the future development of the Auburn North 

Secondary Plan area. This area which lies north of Thompson Creek along Armour 

Road is slated for development as single and multi-family residential areas and local 

commercial areas. A part of it lies within the boundary of the Thompson Creek 

watershed but that area currently drains to a gravel pit and contributes no flow directly 

to Thompson Creek. In order to facilitate development, the area would have to be filled 

and could potentially contribute post-development flows to the creek. Since this could 

be potentially detrimental to the creek, the study identified a preferred stormwater 

management facility location adjacent to the Otonabee River which would prevent 

additional flow entering Thompson Creek. By directing both the majorand minor 

system flow to that location, the “effective” drainage area of Thompson Creek will 

remain as at present. This is the basis used for modeling future land use conditions 

north of Thompson Creek in the present study. 

Thompson Creek Master Drainage Study (1992) 

Totten Sims Hubicki Associates carried out this study in April 1992 for Otonabee 

Region Conservation Authority. The purpose the study was to recommend methods for 




minimizing the impact of proposed development on the natural state of the Thompson 

Creek corridor while allowing the development to proceed. 

The study provides a number of recommendations on SWM strategy, natural 

environment and recreational potential of the Thompson Creek. 

3.2.2 Available Data and Data Gaps 

The purpose of the current study was to develop a Detailed Flood Reduction Plan for 

the Thompson Creek study area based upon a technical analysis of flood vulnerability 

and potential remedial measures in an environmental assessment framework. The data 

required to do this study must be consistent with that purpose. A key question to be 

answered before proceeding with the analysis phase of the study was whether there 

were any critical data gaps which would prevent the completion of the required 

analyses. The approach used in the study was to develop an understanding of existing 

conditions (as a basis for environmental assessment and identification of specific flood 

problems) and then to develop and use various models/tools to test whether potential 

remedial options would be successful in addressing the flooding issues identified. 

Hence the assessment of data gaps was based upon whether there was sufficient 

information to characterize and understand existing conditions and to develop the 

necessary tools/models to assess remedial options. 

The types of data required included: 

Physiographic Data 

 

 

 

 

 

Topographic data (contour mapping) 

Land use data 

Drainage network information (plan and database of drainage infrastructure) 

Soils and/or surficial geology mapping 

Geomorphological data 

Hydrometeorogical Data 

 

 

 

 

Flow data for Thompson Creek 

Flow data for local drainage areas (i.e. storm sewer flows) 

Meteorological data (precipitation) 

Water level data for flood prone areas 

Water Quality Data 

 

Measurements for a range of parameters for surface water to characterize 

general conditions 




Biological Data 

 

 

 

 

 

 

 

Fish community data for Thompson Creek 

Fish habitat data for Thompson Creek 

Vegetation mapping (Ecological land classification) 

Wildlife, bird, herptofauna sighting data 

Wildlife, bird, herptofauna habitat data 

ESA, ANSI mapping 

VTE and species at risk data 

Reviewing these requirements in relation to the available data, indicated the following: 

 

All required physiographic data with the exception of geomorphic data was 

available in suitable form from either the City of Peterborough or ORCA. Part 

of the proposed work program included the completion of a Rapid Geomorphic 

Assessment for the Thompson Creek to fill this potential data gap. Topographic 

mapping was provided in the form of an AutoCad file with a contour interval of 

0.5m. This was sufficiently accurate for mapping of flood lines and is 

consistent with the requirements of Ontario’s Technical Guidelines for Flood 

Plain Mapping. Sewer infrastructure data was provided as ARCVIEW .shp 

files with an associated database. There was some uncertainty regarding the 

accuracy of some components of the this database. Hence field surveys were 

completed to verify or modify those elements. Approximately 50% of sewer 

manholes were surveyed to obtain the ground elevation and pipe inverts. They 

were then compared to the information in the database. If necessary, the 

database was modified. In some cases, invert/ground surface elevations were 

not available and were obtained directly from the field surveys. The data was 

used to construct computer models of the storm sewer system. Using the 

combination of the sewer database and surveyed data, the models were 

sufficiently accurate for the purposes of the present study. 

 

Hydrometeorological data is generally available but the following data gaps 

were identified: 

• There is no flow data on Thompson Creek or on any of the local drainage 

storm sewers. This would have limited the ability to verify that the 

hydrologic models of the watershed were representative of its 

characteristics. Hence a short term flow monitoring program was 

initiated to address this data gap. 




• There are a limited number of anecdotal observations of water levels 

during the July 2004 storm. These can be used to check the hydraulic 

model simulation of that event. Although limited in number, this was not 

judged to be a critical data gap. 

 

 

Water quality data is generally quite limited. However, when supplemented 

with some observations of temperature and dissolved oxygen collected during 

fish habitat surveys during this study, it was sufficient to generally characterize 

Thompson Creek water quality conditions. 

Available biological data was found to be very limited and insufficient to 

complete the characterization of existing conditions and permit an assessment 

of potential impacts/benefits of any proposed flood protection options. Hence 

the work program included field investigations to characterize the fish 

communities and fish habitat of Thompson Creek and to identify vegetation 

communities such that Ecological Land Classification mapping of the riparian 

corridor could be completed and bird and wildlife populations could be 

identified.. 

In summary, a number of data gaps were identified which were judged to be sufficiently 

critical that a series of field investigations were required so that this study could 

proceed to a reasonable conclusion. These programs were completed and are described 

in subsequent sections of this report. 

3.3 NATURAL ENVIRONMENTAL RESOURCES 

The existing natural environmental resources which may affect the development of a 

detailed flood reduction plan or conversely be affected by the implementation of such a 

plan are described in the following sections. 

3.3.1 Fish Community and Fish Habitat 

Thompson Creek originates at a dam on the Trent Canal located 400 m northeast of 

Scollard Drive and generally flows in a southwesterly direction eventually discharging 

into the Otonabee River approximately 300 m west of Armour Road. For the purposes 

of this report, Thompson Creek has been divided into four reaches that have been 

informally named Reach 1, Reach 2, Reach 3 and Beaver Pond (Figure 3.3.1). Reach 1 

originates at the Trent Canal dam and flows in a westerly direction to the Beaver Pond 

located approximately 300 m downstream. Reach 2 originates at the Beaver Pond and 

flows in a southwesterly direction to Armour Road where Thompson Creek crosses 


REACH 1 

STATION 1 

Otonabee River 

STATION 3 

STATION 3A 

STATION 2B STATION 2D 

STATION 2A 

REACH 2 

STATION 2C 

BEAVER POND 

STATION 4 

STATION 5 

REACH 3 

Trent Canal 

Figure 3.3.1: 


Fish Habitat Sampling Locations 

M:\Jobs\2006\14.06605.01.EN1 - Thompson Creek Flood Reduction Study\mapping\GIS\mxd\fish_sampling_reaches.mxd



under the road via a concrete box culvert. Reach 3 originates at Armour Road and 

flows in a southwesterly direction eventually discharging into the Otonabee River 300 

m west of Armour Road. 

Fish community investigations resulted in the capture of a warmwater fish community 

consisting of 11 species including seven baitfish species, two panfish species and two 

game fish species. Aquatic habitat in the creek consists of a combination of beaver 

ponds and natural channel that flows through a combination of forested and open field 

habitats. A large beaver pond is located approximately 250 m downstream of the Trent 

Canal dam that consists of a combination of lentic and shallow littoral habitats. 

3.3.1.1 Data Collection Methodology 

Prior to conducting fish community investigations in Thompson Creek, a Licence to 

Collect Fish for Scientific Purposes (Licence No.1032442) was obtained from the 

Ministry of Natural Resources (MNR). Fish community investigations were conducted 

in Thompson Creek during June and July 2006 using a combination of minnow traps, 

pot traps and a backpack electrofisher. As per the conditions set forth in the Licence to 

Collect Fish for Scientific Purposes minnow traps were used to sample the fish 

community during June 2006 to minimize impacts to spawning fish. A backpack 

electrofisher (Smith-Root model 15D set to 400 volts, 60-80 Hz) was used in July to 

sample four locations that consisted of a 40 m length of stream using a single pass 

method. All available habitats within the 40 m reach were sampled to obtain an 

accurate representation of the fish community at each station. Minnow and pot traps 

were also used during the July investigations to sample deeper habitats in the large 

beaver pond and smaller beaver ponds located downstream. Traps were set in the 

vicinity of cover (aquatic vegetation, woody debris) and/or at the boundary between 

two vegetation communities (i.e. floating aquatic vegetation and submergent vegetation 

communities) for a period of 24 hours. All fish captured were recorded on field 

collection data sheets and released unharmed into the watercourse. 

A general inventory of the habitat attributes along the entire length of Thompson Creek 

was completed during the June field investigations. Attributes including general habitat 

features and average channel width were recorded during the investigations. A detailed 

inventory of the aquatic habitat conditions was conducted at each of the stations 

sampled using a backpack electrofisher during the July investigations. Water quality 

parameters including water temperature, total dissolved solids (TDS), conductivity, pH 

and dissolved oxygen (DO) were recorded at each station. Water temperature, TDS, 

conductivity and pH were measured using a Hanna Instruments HI98129 multimeter 

and DO was measured using an Extech Instruments Waterproof Exstik II Dissolved 

Oxygen Meter. Physical habitat features including channel morphology (percent pools, 




riffles, runs), substrate composition, presence of barriers, percent canopy cover, riparian 

vegetation community, water clarity, and presence of aquatic vegetation was recorded 

for each station. The 40 m sample reaches were then divided into 5 transects, each 10 

m apart and then subdivided into 5 points equally spaced across the channel based upon 

bankfull width at the transect. Data recorded at each transect includes bankfull width, 

wetted width, water depth measured at each point and dominant substrate. 

3.3.1.2 Summary and Conclusions re. Fisheries 

A detailed description of the fish communities and fish habitat by Reach is presented in 

Appendix D. These should be considered in the impact assessment of any flood 

protection alternatives that directly affect the creek. The following provides a summary 

of the findings. 

The fish community captured in Thompson Creek indicates that the creek functions as 

warmwater habitat. Although coolwater species are present, these species are tolerant 

of a wide thermal range and are commonly captured in warmwater habitats. The 

presence of blackchin shiner indicates that the creek has clear water and good water 

quality as it is intolerant to turbidity and pollution. Top predator species including 

largemouth bass, rock bass and smallmouth bass were captured at many of the sampling 

stations indicating that Thompson Creek can support these species. The presence of 

YOY rock bass and largemouth bass indicates that the slow moving, well vegetated 

areas are functioning as nursery habitat for these species. There is likely a reproducing 

population of these species in the creek as the dense submergent vegetation and coarse 

substrate provides suitable spawning habitat for these fish. Furthermore, adult 

Centrarchid species were observed in suitable spawning habitat during June 

investigations suggesting they were spawning. 

Upstream of Armour Road, in-water cover is abundant providing refuge areas and 

potential nursery habitat for the fish community captured during investigations. 

Downstream of Armour Road, in-water cover is reduced and the lack of submergent 

vegetation is likely the result of canopy cover increasing in density along this reach. 

Although in-water cover in Reach 3 is not as dense as the remainder of the creek, a 

similar fish community was captured in the reach. The presence of a similar fish 

community within Thompson Creek suggests that water quality and habitat conditions 

are similar throughout the creek. 




3.3.2 Terrestrial Features: Wetlands, Vegetation and Wildlife 

3.3.2.1 Vegetation 

The natural vegetation within the study area was documented by a reconnaissance level 

field survey conducted on 5-6 June 2006. The types of vegetation present were 

classified and described with reference to the Ecological Land Classification for 

Southern Ontario (Lee et al. 1998). The conservation status of observed vascular plants 

was determined with reference to the Species at Risk Ontario List (30 June 2006) 

(OMNR 2006), the Ontario Plant List (Newmaster et al. 1988), and the Checklist of the 

Vascular Plants of Peterborough County (Oldham 1999). The conservation status of 

observed vegetation types was determined with reference to Southern Ontario 

Vegetation Communities (Bakowsky 1997) and to consultation with Wasyl Bakowsky, 

Community Ecologist, Natural Heritage Information Centre. 

The natural vegetation within the study area is composed of forests, wetlands, 

hedgerows, thickets, regenerating woodlands, old-field meadows and conifer plantation. 

Coniferous, mixed and deciduous forests have established on fresh to moist mineral 

soils on the upland margins of Thompson’s Creek, whereas mixed swamps, deciduous 

swamps, thicket swamps, meadow marshes and shallow marshes have established on 

the flooded margins of the large beaver pond and on moist to wet soils on the lowland 

margins of Thompson’s Creek. Hedgerows, thickets, patches of regenerating forest, 

and old-field meadows have established on former farm fields and field margins. A 

conifer plantation has been planted on tableland adjacent to the Otonabee River. 

Twenty-five vegetative types (Lee et al. 1998) were observed during the ecological land 

classification of the study area (Figure 3.3.2). The most common forest types were 

Fresh-Moist Manitoba Maple Lowland Deciduous Forest (FOD7-7) and Fresh-Moist 

Lowland Ash Deciduous Forest (FOD7-2). The most common wetland types were 

Willow Mineral Thicket Swamp (SWT2-2), Alder Mineral Thicket Swamp (SWT2-1), 

Cattail Mineral Shallow Marsh (MAS2-1), Green Ash Mineral Deciduous Swamp 

(SWD2-2), and White Cedar – Hardwood Mineral Mixed Swamp (FOM1-1). The most 

common cultural vegetation types were Fresh-Moist Old Field Meadow (CUM1-1), 

Ash-Elm-Basswood Cultural Woodland (CUW) and Crabapple-Hawthorn-Buckthorn 

Cultural Thicket (CUT1-7). None of the observed vegetation types is rare in Ontario 

(Bakowsky 1995). The conservation status of Silky Dogwood Mineral Thicket Swamp 

(S3/S4) warrants review and is expected to be downgraded to S4 status (W. Bakowsky, 

personal communication, July 2006). 

Two-hundred-and-eleven species of vascular plants were recorded during the level 

botanical survey (Appendix E). Five species are rare in Peterborough County (Burke et 


NOT CLASSIFIED 

FOD7-7 

FOD7-7 

CUW 

CUW 

CUM17 

FOD7-6 

CUM1-1 

FOD7-7 


CUP3-1, CUP3-3 

FOD7-7 

CUW 

SWT2-2, SWT2-8 

SWD2-2, FOM7-2, FOD7-2 

FOD8-1 

CUM1-1 

CUW 

CUW 

CUM1-1 

CUM1-1 


SWT2-2, MAS2-1, MAM2-2 

CUM1-1 

CUW 

FOD7-2 

SWT2-2 

CUW 

CUW 

CUM1-1 

SWT2-1 

CUT1-7 

CUM1-1 

CUM1-1 

SA 

FOC4-1 

MAS2-1 

Not Classified 

CUM1-1, CUT1-7 

CUW 

CUW 

SWT2-1 

SA 

CUT1-7, CUW 

CUM1-1, CUT1-7 

MAS2-1 

SWT2-2, MAS2-1 

CUT1-7 

SA 

SWT2-2 

SWT2-2 

MAS2-1 

CUT1-7 

CUT1-7 

CUM1-1 

SWT2-2 

CUW 

SWT2-5 

CUW 


CUW 

SWT2-2, MAS2-1, MAS2-9, MAM2-2, MAM2-7 

CUW 

CUM1-1 

CUW 

FOC4-1 


SWT2-8 

FOC4-1 

FOC4-1 

SA 

SWM1-1 

CUT1-7 

CUT1-1, CUM1-1 

SA 

CUM1-1 

MAS2-3 

SWT2-2, MAM2-5 

MAS2-1, MAS2-2, MAS2-7 

CUM1-1 


DETAILED FLOOD 

REDUCTION STUDY 

FIGURE 3.3.2 

ELC VEGETATION TYPES 


Legend 

Site Boundary 

FOC4-1 Fresh-Moist White Cedar Coniferous Forest 

FOM7-2 Fresh-Moist White Cedar - Hardwood Forest 

FOD7-2 Fresh-Moist Ash Lowland Deciduous Forest 

FOD7-6 Fresh-Moist Black Locust Deciduous Forest 

FOD7-7 Fresh-Moist Manitoba Maple Lowland Deciduous Forest 

FOD8-1 Fresh-Moist Poplar Deciduous Forest 

CUP3-1 Red Pine Coniferous Plantation 

CUP3-3 Scotch Pine Coniferous Plantation 

CUM1-1 Dry-Moist Old Field Meadow 

CUT1-1 Sumach Cultural Thicket 

CUT1-7 Buckthorn-Hawthorn-Crabapple Cultural Thicket 

CUW Ash - Elm - Basswood Cultural Woodland 

SWM1-1 White Cedar - Hardwood Mineral Mixed Swamp 

SWD2-2 Green Ash Mineral Deciduous Swamp 

SWT2-1 Alder Mineral Thicket Swamp 

SWT2-2 Willow Mineral Thicket Swamp 

SWT2-5 Red-osier Mineral Thicket Swamp 

SWT2-8 Silky Dogwood Mineral Thicket Swamp 

MAM2-2 Reed-canary Grass Mineral Meadow Marsh 

MAM2-5 Narrow-leaved Sedge Mineral Meadow Marsh 

MAM2-7 Horsetail Mineral Meadow Marsh 

MAS2-1 Cattail Mineral Shallow Marsh 

MAS2-2 Bulrush Mineral Shallow Marsh 

MAS2-7 Bur-reed Mineral Shallow Marsh 

SA Shallow water 

CUM1-1 

M:\Jobs\2006\14.06605.01.EN1 - Thompson Creek Flood Reduction Study\mapping\GIS\mxd\veg_communities.mxd



3.3.2.2 Birds 

al. 1999): Black Walnut (Juglans nigra), Common Hackberry (Celtis occidentalis), 

Holme’s Hawthorn (Crataegus holmesiana), Pringle’s Hawthorn (Crataegus pringlei), 

and, Emerson’s Thorn (Crataegus submollis) (Figure 3.3.3). The three species of 

hawthorn represent new records for Peterborough County. 

A brief description of each vegetation type is included in Appendix E. 

The breeding birds within the study area were identified by field survey on 2 June 2006 

from 0630 to 1030 hours. The date and time of day were judged to be optimal for the 

detection of breeding birds. At this date, the spring migration in southern Ontario is 

largely complete and most species are breeding (Cadman et al. 1987). Breeding species 

were surveyed using the point-count protocol of the Ontario Breeding Bird Atlas 

(2001). In accordance with the protocol, point-counts were conducted for 5 minutes 

from fixed locations. Point counts were situated so that all habitat types present were 

surveyed (Figure 3.3.4). Incidental observations of birds detected outside of pointcounts 

were also recorded. Weather conditions during the survey were ideal with calm 

winds, temperatures varying from 15-20 0 C and no precipitation. 

Observed bird species were classified in relation to five habitat types: pond, old field 

meadow, thickets, mixed swamp, and deciduous forest (Figure 3.3.4). This 

classification broadly conforms to the ELC vegetation types described in 

Section 3.3.2.1. A listing of the ELC vegetation types in each habitat type is presented 

in the “Notes” to Table 3.3.1 

The conservation status (local abundance) of observed birds was determined with 

reference to the Species at Risk Ontario List (30 June 2006) (OMNR 2006), and, to the 

1998 Summary of Peterborough County Birds (Burke 1999). 

Forty species of breeding birds were recorded during the survey (Table 3.3.1). None of 

the recorded species is a Species at Risk in Ontario or is rare in Peterborough County. 

Several species are members of suites of birds that are vulnerable to urban 

development: “area-sensitive” birds (Freemark and Collins 1989, Johnson 2001, 

Sparrow et al. 2005) and, birds that experienced range-wide population declines during 

the period 1966-2004 (Sauer 2005). Area-sensitive birds are species that require 

extensive forest or grassland habitat in the surrounding landscape to persist (Freemark 

and Collins 1989, Tate 1998, Couturier 1999). The following eleven species of 

breeding birds were classified as “Area-Sensitive”: American Crow, American 

Redstart, Black-and-white Warbler, Brown Thrasher, Eastern Meadowlark, Field 

Sparrow, Pied-billed Grebe, Red-eyed Vireo, Rose-breasted Grosbeak, Savannah 


M:\Jobs\2006\14.06605.01.EN1 - Thompson Creek Flood Reduction Study\mapping\GIS\mxd\rare_vascular_Plants.mxd 

!( 

!( 

!( 

!( 

!( 

3 

6 

4 

7 

9 

5 

2 

8 

!( 

!( 

1 




FIGURE 3.3.3 

RARE VASCULAR 

PLANTS 


Legend 

Study Boundary 

!( Rare Vascular Plants 

Common Names Species 

1 Black Walnut 

2 Common Hackberry 

3 Holme's Hawthorn 



6 Pringle's Hawthorn 



9 Emerson's Thorn 

Juglans nigra 

Celtis occidentalis 

Crataegus holmesiana 



Crataegus pringlei 



Crataegus submollis 

!(

M:\Jobs\2006\14.06605.01.EN1 - Thompson Creek Flood Reduction Study\mapping\GIS\mxd\birdhabitats.mxd 




FIGURE 3.3.4 

BIRD HABITATS 


Legend 

Study Boundary 

Bird Survey Stations 

Deciduous Forest 

Mixed Forest 

Old Field 

Pond 

Shrub Dominated



Sparrow and Swamp Sparrow. The following nineteen species experienced significant 

range-wide population declines during the period 1966 – 2004: Baltimore Oriole, 

Belted Kingfisher, Black-and-white Warbler, Blue Jay, Brown Thrasher, Brown- 

Headed Cowbird, Common Grackle, Common Yellowthroat, Eastern Kingbird, Eastern 

Meadowlark, Eastern Wood Pewee, European Starling, Field Sparrow, Green Heron, 

Northern Flicker, Red-Winged Blackbird, Rose-breasted Grosbeak, Savannah Sparrow, 

and Song Sparrow. 

A numerical summary of the breeding species of conservation interest by habitat type is 

presented in Table 3.3.2. 




Table 3.3.1 

List of Breeding Birds in Thompson Creek Study Area & Conservation Status 

Common Name Scientific Name Area Sensitivity 1 Habitat Use 2 Local Abundance 3 Population Trend 4 Habitat 

Type 5 

Alder Flycatcher Empidonax alnorum U E C S M, P, T 

American Crow Corvus brachyrhynchos S E C I M, 

American Goldfinch Carduelis tristis I E C S M, S, D, T 

American Redstart Setophaga ruticilla S I C S D, 

American Robin Turdus migratorius I E C I M, S, D, T 

Baltimore Oriole Icterus galbula I E C D M, D, 

Belted Kingfisher Ceryle alcyon I U D P, 

Black-and-white Warbler Mniotilta varia S I C D S, D, 

Black-capped Chickadee Poecile atricapillus I I/E C I M, S, D, T 

Blue Jay Cyanocitta cristata I I/E C D M, D, T 

Brown Thrasher Toxostoma rufum S C D M, T 

Brown-headed Cowbird Molothrus ater I E C D M, D, T 

Cedar Waxwing Bombycilla cedrorum I E C I M, P, D, T 

Common Grackle Quiscalus quiscula I E C D M, P, D, T 

Common Yellowthroat Geothlypis trichas I I/E C D P, T 

Eastern Kingbird Tyrannus tyrannus I E C D M, T 

Eastern Meadowlark Sturnella magna S C D M, 

Eastern Phoebe Sayornis phoebe U I/E C I P, D, 

Eastern Wood Pewee Contopus virens I I/E C D D, 

European Starling Sturnus vulgaris I E C D M, T 

Field Sparrow Spizella pusilla S C D M, 

Gray Catbird Dumetella carolinensis I I/E C S D, T 

Great Blue Heron Ardea herodias I C I P, 

Green Heron Butorides virescens I U D P, 

House Wren Troglodytes aedon I E U I M, D, T 

Mallard Anas platyrhynchos I C I P, 




Common Name Scientific Name Area Sensitivity 1 Habitat Use 2 Local Abundance 3 Population Trend 4 Habitat 

Type 5 

Mourning Dove Zenaida macroura I E C S M, S, D, T 

Northern Cardinal Cardinalis cardinalis I I/E C S M, D, T 

Northern Flicker Colaptes auratus I I/E C D M, D, 

Pied-billed Grebe Podilymbus podiceps S U S P, 

Red-eyed Vireo Vireo olivaceus S I/E C I D, 

Red-tailed Hawk Buteo jamaicensis I E C I M, 

Red-winged Blackbird Agelaius phoeniceus I E C D P, D, T 

Rose-breasted Grosbeak Pheucticus ludovicianus S I/E C D M, S, D, 

Savannah Sparrow Passerculus sandwichensis S I C D M, 

Song Sparrow Melospiza melodia I E C D M, P, S, T 

Swamp Sparrow Melospiza georgiana S E C I P, 

Tree Swallow Tachycineta bicolor U E C S P, 

Warbling Vireo Vireo gilvus U E U I M, P, D, T 

Yellow Warbler Dendroica petechia U E C S M, S, D, T 

1. S: Area sensitive, I: Area insensitive, U: Area sensitivity unknown. Most data from Freemark and Collins 

(1989). Data for Brown Thrasher, Eastern Meadowlark, Field Sparrow and Savannah Sparrow from Johnson 

(2001). Data for Belted Kingfisher, Great Blue Heron, Green Heron, Mallard, Pied-billed Grebe and Swamp 

Sparrow from Crewe and Timmermans (2005) 

2. I: Interior, I/E: Interior and edge, E: Edge. Most data from Freemark and Collins (1989). Data for Savannah 

Sparrow from Johnson (2001). 

3. Peterborough County Breeding Status. C: Common, U: Uncommon. From Burke et. al. (1999). 

4. D: Declining, I: Increasing, S: Stable. Survey-wide data 1966-2004. From Sauer et. al. (2005). 

5. Habitat Type: P: Pond, D: Deciduous Forest, S: Swamp, M: Old-Field Meadow; T: Thickets 

6. ELC Vegetation Types by Habitat 

Pond: SWT2-2, MAM2-2, MAS2-1, MAS2-9, SA 

Deciduous Forest: FOC4-1, FOD7-2, FOD7-6, FOD7-7, FOD8-1, CUW, SWD2-2, SWT2-2, SWT2-8 

Swamp: SWM1-1, FOM7-2, FOD7-2 

Old-Field Meadow: CUM1-1, CUT1-7, CUW, MAS2-3 

Thickets: CUT1-1, CUT1-7, CUW, CUM1-1, SWT2-1, SWT2-2, 




Table 3.3.2 

Numerical Summary of Breeding Species of Conservation Interest by Habitat 

Type 

3.3.2.3 Wildlife 

# of Area 

Sensitive 

Species 

# of Locally 

Uncommon 

Species 

# of Range-wide 

Declining 

Species 

Habitat 

Old Field Meadow 6 2 14 

Pond 2 4 6 

Mixed Forest 2 0 3 

Deciduous Forest 4 2 9 

Thicket 1 2 10 

Incidental observations of amphibians, reptiles and mammals were recorded while 

conducting other field surveys. Green Frog (Rana clamitans) and Bullfrog (Rana 

catesbeiana) were heard calling from wetlands on the margins of the beaver pond and 

adjacent to Thompson Creek. One Snapping Turtle (Chelydra serpentina serpentine) 

was observed on the margins of the beaver pond and a Midland Painted Turtle 

(Chrysemys picta) was observed laying eggs in an old-field meadow on the south side 

of Thompson Creek. One Eastern Gartersnake was observed in a willow thicket swamp. 

Beaver dams and lodges were observed downstream of the beaver pond and one Beaver 

(Castor canadensis) was observed swimming in the pond. A Muskrat (Ondatra 

zibethicus) was observed in Thompson Creek downstream of the Trent Canal dam and 

two White-tailed Deer (Odocoileus virginianus) were observed in deciduous forest and 

old-field meadow. 

References cited in Section 3.3.2 are presented in Appendix E. 

3.3.3 Fluvial Geomorphology 

During the current study, a Rapid Geomorphic Assessment (RGA) survey was 

completed of Thompson Creek from its confluence with the Otonabee River to the 

Thompson Creek Dam. The water course were divided into a series of four 

representative reaches for evaluation purposes. A total of nine cross-sections were 

chosen to represent those four reaches. Figure 3.3.5 shows the extent of each reach and 

the nine sampled locations. Typical conditions in each reach are shown in a series of 

photographs in Photographs 3.3.1 to 3.3.6 at locations which are referenced on 

Figure 3.3.3. The detailed results are included in Appendix F. Table 3.3.3 summarizes 

the geomorphic parameters for each of the sampled locations. A detailed description of 

the habitat and stream conditions was provided in Section 3.3.1 and Appendix D. 


4a 

4b 

4c 

Reach #4 

Assessment 

Locations 

2c 

Reach #3 

2b 

2a 

Reach #2 

1c 

1b 

Reach #1 

1a 

Figure 3.3.5: Geomorphology Survey Locations - Thompson Creek



Reach 

No. 

Sub- 

Reach 

Bankfull 

Width 

(m) 

Table 3.3.3 

Geomorphic Characteristics of Thompson Creek 

Bankfull 

Depth 

(m) 

Slope 

(%) 

Entrenchment Planform RGA 

Score 

Substrate 

Bed 

Material 

D50 

(cm) 

1 1-a 8.5 0.69 0 Low Straight 3 Cobble n/a 

1-b 5.3 0.36 0.2 Moderate Straight 5 Gravel/pebble n/a 

1-c 10.7 0.66 0 Low Straight 3 Silt n/a 

2 2-a 11.9 0.36 0.1 Low Sinuous 3 Silt n/a 

2-b 8.9 0.33 0.2 Low Sinuous 3 Cobble 12 

2-c 8.4 0.53 0.2 Low Straight 0 Cobble with n/a 

Boulders 

3 Beaver n/a n/a n/a n/a n/a n/a n/a n/a 

Pond 

4 4-a 10.2 0.25 0.5 Low Sinuous 5 Platey cobble 9 

4-b 5.6 0.43 0.5 Low Sinuous 0 Platey cobble n/a 

4-c 19.6 0.84 0 Low Sinuous 2 Silt with n/a 

Boulders 




Photo 3.3.1: Near Outlet 

Photo 3.3.2 Armour Rd 




Photo 3.3.3: Channel Upstream of Armour Road 

Photo 3.3.4: Outlet of Main Beaver Dam 




Photo 3.3.5: View of Main Beaver Pond 

Photo 3.3.6.: Channel Downstream of Dam 




3.3.4 Water Quantity Characteristics 

As noted earlier, there are no historical flow-measurements within the Thompson Creek 

watershed or any of the local areas draining directly to the Otonabee River. A short 

term flow monitoring program was completed to address this data gap and is described 

in Section 4.2.3. In general, however, the flow regime of Thompson Creek is somewhat 

unusual in that its headwaters were disconnected from its lower section when the Trent 

Canal was constructed. Inflows to the upper end of Thompson Creek are controlled by 

the Thompson Creek Dam which consists of a concrete structure with a number of stop 

logs. The stop logs have not been actively operated for some years but leakage occurs 

through them sustaining a reasonably constant flow through Thompson Creek. This has 

been estimated to be in the range of 0.1 m 3 /s to 0.15 m 3 /s. The water level on the 

upstream side of the Thompson Creek Dam is controlled by the water level at the 

Nassau Dam on the Otonabee River. It is understood that during times of high flow, the 

water level has risen sufficiently to cause some water to spill over the top of the stop 

logs in the Thompson Creek Dam. This would cause a temporary increase in flow in 

Thompson Creek. 

At the time of this report (2006), the Thompson Creek watershed downstream of the 

dam was partially natural and partially developed (see Section 3.4 for discussion of land 

use). Subdivisions have been constructed east and west of Armour Road on the south 

side of the Thompson Creek. Runoff from these partly impervious areas causes short 

term inflows to the creek during rainfall events which are significantly larger than the 

background flow (baseflow) in the creek. Runoff from the undeveloped areas is 

extremely low by comparison. Field observations indicated that there are a series of 

beaver dams and other low rock weirs across the creek between Armour Road and the 

Thompson Creek Dam. The most upstream of these has formed a large beaver pond 

which extends to about 250 m downstream of the dam. Although not permanent, 

engineered structures, these dams appear to “damp” the flows from the development 

east of Armour Road (the Waverley Heights subdivision) resulting in lower than 

expected peak flows west of Armour Road (see discussion of monitoring results). It is 

understood that ultimately a stormwater management facility will be constructed to 

control the outflows from the existing and future phases of the Waverley Heights 

subdivision. This will help reduce the impact of those flows on Thompson Creek. 

The hydrologic characteristics of Thompson Creek and the local drainage areas were 

investigated and modelled in detail during this study as described in Section 4. 




3.3.5 Water Quality Characteristics 

There is a relatively limited amount of water quality data available for Thompson 

Creek. Information collected during the City of Peterborough Pollution Control Plan 

Report (1989)” from the “Thompson Creek Management Plan (2004)” and from the 

field investigations completed during this study are reproduced in Table 3.3.4. 

Table 3.3.4 

Surface Water Quality Data in Thompson Creek Watershed 

Information Source 

Water Quality Parameters 

TP 

(mg/l) 

TSS 

(mg/l) 

Cl 

(mg/l) 

TKN 

(mg/l) 

Nitrate 

(mg/l) 

Fecal 

Coliform 

pH 

D.O. 

MaxWater 

Temp ( o C) 

D/S Thompson Dam 

(PCP 1989) 

0.024 - 8.6 0.045 0.026 31 – 127 - - - 

Outlet to Otonabee 

(PCP 1989) 

0.030 - 9.2 0.473 0.028 92 - 244 - - - 

D/S Thompson Dam 

(ORCA 2004) 

< 0.02 8 10 -11 34.6 

Armour Road 

(ORCA 2004) 

< 0.02 2 - 20 - - < 0.1 6 -128 7.8 10 – 11 32.8 

These values indicate that the water quality of Thompson Creek is quite good. Most 

parameters meet the Provincial Water Quality Objectives (PWQO). This is supported 

by the presence of pollution intolerant fish species and submergerged aquatic 

vegetation. 

3.3.6 Surficial Soils/Geology/Hydrogeology 

The surficial soils and geology of a watershed play an important role in determining its 

hydrologic response. Where soils are impermeable, direct surface runoff rates tend to 

be higher and low flows tend to be lower. Where soils are permeable (e.g. sand and 

gravels) the watershed response tends to be less “flashy” and baseflows tend to be 

higher and more sustained. These trends will, of course, be modified by land uses 

which change the watershed’s imperviousness. The underlying geology and the 

associated hydrogeological system also influence the watershed response depending 

upon how local and regional aquifers interact with the surface water courses. For 

example, deep regional aquifers which are recharged many kilometres from a local 




stream may be intersected in its watershed and provide sustained baseflows which 

would not be present from only local recharge. 

The Soil Survey of Peterborough County (Ontario Soil Survey Report No. 54 provides 

a description of the geology and surficial soils of the study area. Additional 

information was also avalailable from the recent geotechnical studies of the Waverly 

Heights area. The bedrock is limestone of the Trenton Formation from the Ordovician 

period. It was reported to be between 0.8 m and 2.4 m below the ground surface in the 

south east sector of the Thompson Creek watershed (Trow, 2006). The surficial 

geology consists of till plains which have been drumlinized and fluted by historical 

glacial activity. The till is thick, moderately stony, calcitic limestone till. The water 

table was reported to be between 0.8 m and 2.4 m below the ground surface in the 

Waverley Heights area (Trow, 2006). 

The Peterborough County Soil Survey map indicates the soils consist of Otonabee loam 

(Ol-B2) on south side of Thompson Creek (Waverly Heights area). Along the creek 

itself, it indicates undifferentiated, poorly drained organic soils (O). On north side it 

indicates Cramahe sandy gravelly loam (Cs-C2). In the golf course area there is a sliver 

of Emily loam (El-B4). Although mapping does not cover all the study area to Parkdale 

Rd., it implies a continuation of the Otonabee loam through the area.. 

Figure 3.3.6 shows the surficial soils of the Thompson Creek study area. This 

information was used during the development of hydrologic models to ensure the 

appropriate runoff characteristics are reproduced (See Section 4.4). 

3.4 SOCIO-ECONOMIC ENVIRONMENT 

3.4.1 Existing Land Use 

The Thompson Creek watershed lies within the northeast quadrant of the City of 

Peterborough within the Ashburnham Ward (4) of the City. Figure 3.4.1 indicates the 

distribution of designated land uses within the study area based upon the Official Plan. 

These vary from residential to local commercial to major open space. It should be 

noted that not all of the designated residential and commercial lands have been 

developed at the time of this report. Figure 3.4.2 is an aerial photograph that shows the 

existing limits of development. Table 3.4.1 shows the percentage of each land within 

the main Thompson Creek drainage area and the local areas draining to the Otonabee 

River. The importance of mapping and quantifying this information is that each land 

use has a different potential to generate storm runoff and must be considered in the 

hydrologic modelling (Section 4.4). 




LEGEND: 

Figure 3.3.6 

Surficial Soils of Thompson Creek Study Area 




Study Area Boundary 

Figure 3.4.1: Land Use Within Study Area According to Official Plan Schedule A 





Watershed Boundary 

Study Area Boundary 

Figure 3.4.2: Current Land Use Within Study Area 




Table 3.4.1 

Approximate Distribution (%) of Land Uses in the Thompson Creek Study Area 

Land Use Designation 

Subwatershed Residential Commercial Major Open 

Space/Undeveloped 

Existing 

Thompson Crk. 39 - 61 

Other Areas 33 - 67 

Future 

Thompson Crk. 61 3 36 

Other Areas 33 - 67 

3.4.2 Future Land Use 

The anticipated future growth within the study area is identified in the City of 

Peterborough’s Official Plan (O.P.). The study area is part of the Auburn North 

Secondary Plan Area established in 2002. Figure 3.4.3 shows the land use structure 

anticipated in that document. Table 3.4.1 shows the comparative land use distribution 

values for future conditions. As indicated, extensive additional urban development is 

anticipated on both the south and north side of Thompson Creek within its watershed 

boundaries. No land use changes are anticipated within the local drainage areas which 

drain directly to the Otonabee River as the area is currently fully built out. 

3.5 SUMMARY OF EXISTING ENVIRONMENTAL CONDITIONS 

The previous sections have described the baseline environmental conditions in the 

Thompson Creek study area. The following are the main highlights: 

 

 

 

Thompson Creek has a drainage area of about 75 hectares and is controlled at 

its upstream end by the Thompson Creek Dam. This provides a relatively 

constant flow of about 0.1 to 0.15 m 3 /s. 

The creek functions as a warmwater fishery although some coolwater and 

coldwater species are present. 

Water quality in the creek is good as evidenced by its clear, cool appearance, 

the presences of pollution intolerant fish species and certain types of submerged 

aquatic vegetation. 




Figure 3.4.3: Future Land Use Within Auburn North Secondary Plan Schedule N 




 

 

The creek contains a wide variety of habitats ranging from shallow flowing 

sections which flow over bedrock to beaver ponds to altered sections 

downstream of Armour Road. 

The creek is crossed by a number of small dams – some are man-made rock 

weirs, others are beaver dams. 

Riparian vegetation varies considerably, including: forests, wetlands, 

hedgerows, thickets, regenerating woodlands, old-field meadows and conifer 

plantation. Twenty-five vegetative types were mapped in total. 

 

 

 

Forty species of breeding birds were recorded during the survey. None of the 

recorded species is a Species at Risk in Ontario or is rare in Peterborough 

County. 

Incidental sightings of wildlife included: two types of frog, two types of turtle, 

beaver, muskrat, snake and white-tailed deer. 

Considerable additional urban development is anticipated within the Thompson 

Creek drainage area (particularly future phases of the Waverley Heights 

subdivision) 




4.0 PHASE 2 – EXISTING CONDITIONS: FLOOD 

VULNERABILITY 

4.1 GENERAL 

As noted in the introduction, this study was designed to potentially address two types of 

flooding situations which may have occurred in the past or may occur in the future. 

The first of these is water course related, i.e. inadequacies in the capacity of the creek 

channel or culvert crossings which cause flooding to adjacent areas. The second type is 

more localized flooding resulting from inadequacies in the storm sewer systems or local 

roadways/ditches, i.e. lack of capacity for relatively frequent events. These two cases 

required two different approaches to be used in their analysis of flood vulnerability. In 

the first case, which applies only to the Thompson Creek water course, a model 

(OTTHYMO) of the hydrologic response of the watershed as a whole was developed to 

estimate flows in the creek for extreme storm events. These were then used in a 

hydraulic model (HEC-RAS) to calculate corresponding flood water levels. In the 

second case, a more detailed analysis of the internal drainage systems of both the 

Thompson Creek watershed and the local areas draining directly to the Otonabee River 

was required. This required the use of a model (OTTSWMM) which could simulate 

flows in both the sewer pipes and along the streets and any other swales, channels, etc. 

for the extreme events of interest. 

The following sections describe the background information used in the analysis and 

the methods, results and conclusions regarding flood vulnerability in the Thompson 

Creek study area. 

4.2 SUMMARY OF AVAILABLE FLOOD RELATED INFORMATION 

In addition to the background information described in Section 3.2.1, several additional 

reports and pieces of data were available which related directly to the issue of flood 

vulnerability within the Thompson Creek study area. These included: the Flood 

Reduction Master Plan, existing flood plain mapping and flow monitoring data 

collected during the early stages of the current study. The following sections discuss 

these items. 

4.2.1 Flood Reduction Master Plan 

In July 2004, the City of Peterborough was hit by a severe rainfall event that caused 

flood damage in excess of $100 million in direct physical damages to private and public 

property. Shortly after the flood, the City retained UMA Engineering Ltd. (UMA) to 

investigate the causes and determine remedial measures to improve the operation of the 




drainage system and reduce the risk of damage from future flooding. UMA undertook a 

City-wide Flood Reduction Master Plan Study under the Environmental Assessment 

Act. The study included two sets of five ward-based public information meetings – the 

first set gathered information on flooding damage from the public while the second set 

presented alternative solutions and gathered information on public priorities for 

solutions. As part of the consultation process, a Technical Committee provided a wide 

range of input, and a Citizen’s Advisory Committee provided valuable direction on the 

perspectives and interests of the public. 

UMA’s analysis identified the following causes for the flood damage: 

 

 

 

 

Unprecedented heavy rainfall of an intensity of more than twice the current 

design standard used by most municipalities, centred on the largely impervious 

downtown core, resulting in high runoff. 

Insufficient storm sewer capacity caused primarily by ineffective water 

collection and undersized pipes. Approximately 80% of the City’s storm trunk 

sewers analysed do not meet current 5-year design standards. 

Poorly defined overland flow routes caused primarily by filling in of natural 

waterways over time without accommodating the water elsewhere. Over 225 

properties in the City are vulnerable to overland flow damage from a 100-year 

storm event. 

Unwanted water getting into the sanitary sewer system leading to system 

overflow. It is believed to be primarily a result of foundation drain and illegal 

roof leader connections and inflow through aging pipes and manholes. 

The Study identified a range of options which could be applied to address these 

problems. It includes a Master Plan, to determine which solutions to apply, to which 

systems, and in which parts of the City. Priorities established were as follows: 

 

 

preventing basement flooding from sanitary sewage as a priority. 

urgent drainage system attention for four catchments: Jackson, Curtis, 

Byersville/Harper, and Riverview. 

The Master Plan maps out the broad steps to reduce flooding damage in the City and 

outlines the short term activities required to begin the process. The analysis undertaken 

as part of the Master Plan indicates that the City is currently at risk of damage in the 

event of future storms. The Action Plan derived from the Master Plan Study provides 

the broad steps to reduce flooding damages. Important next steps identified were: 




prepare a detailed implementation plan, including amounts / sources of funding and 

other resources.; prepare detailed terms of references for the most urgent action steps. 

The current study was one of the recommended actions included in the Action Plan. 

In addition to the Action Plan, the report recommended continuation of the Technical 

Committee and Citizens Advisory Panel to advise, monitor and report on progress and 

performance, in addition to providing input on public consultation. It also 

recommended that certain key parameters be monitored and reported to demonstrate 

progress in implementing the Plan. 

4.2.2 Existing Flood Plain Mapping 

The Otonabee Region Conservation Authority (ORCA) developed flood plain mapping 

of Thompson Creek as part of the City of Peterborough Flood Risk Mapping Study 

(TSH, 1989/1990). This was based upon hydrologic modelling of the watershed using 

OTTHYMO for the 1 in 2 year to 1 in 100 year storms and the Regional Storm. Flood 

levels were determined using the HEC-2 backwater model. The resulting flood lines 

were plotted on 1:2,000 scale topographic mapping. The regulatory flood line was 

subsequently used by ORCA to regulate development adjacent to the flood plain. The 

hydrologic and hydraulic models and an electronic version of the mapping was 

provided by ORCA at the start of the current study. It proved a useful basis for 

beginning the analysis completed in this project although it was out of date in regard to 

some of the existing watercourse crossings. 

4.2.3 Flow Monitoring 

Prior to the present study, only limited spot measurements of flows in Thompson Creek 

had been obtained in previous studies. To provide a basis for verification of the 

hydrologic and hydraulic models used in this study, a short term continuous streamflow 

monitoring program was initiated. Two water level monitoring gauges were established 

on Thompson Creek itself and a water level/flow monitoring gauge was installed at the 

outlet of the storm sewer system for a significant part of the existing Waverley Heights 

subdivision. Figure 4.2.1 shows the locations of the three gauges. Photograph 4.2.1 

shows the installation near the mouth of Thompson Creek. As indicated, it consisted of 

a stilling well installed inside a protective casing with a pressure transducer (Solinst 

LevelLogger 3001) located below the water level. The pressure transducer contained a 

built in data logger which could be downloaded to a laptop computer via a 

communications cable temporarily attached to it. At the downstream location, a 

barometric pressure logger (Solinst BaroLogger 3001) was also installed as its data was 

required to correct the water level measurements to account for current air pressure. 

The two instream gauges were installed in April 2006 and were removed in September 




2006. During that period, the data was downloaded approximately every three to four 

weeks and the equipment checked to ensure correct operation. Independent streamflow 

measurements were completed using a velocity meter on several of those occasions as a 

basis for development of rating curves. Table 4.2.1 shows information used to derive 

rating curves. Figure 4.2.2 shows a plot of a typical part of the water level record for 

the gauge at the mouth of Thompson Creek. 

Photograph 4.2.1: Temporary Flow Gauge near Mouth of Thompson Creek 

Table 4.2.1: Information Used to Derive Rating Curves 

Day/Time Location/Trial Flow (m 3 /s) 

Water 

Level at 

Gauge (m) 

6/5/06 15:30 Dam/Trial 1 0.1480 0.3296 

6/5/06 16:20 Mouth/Trial 1 0.1910 0.3221 

6/15/06 14:20 Dam/Trial 1 0.0874 0.3079 

6/15/06 15:00 Mouth/Trial 1 0.0383 0.2822 

6/23/06 11:30 Mouth/Trial 1 0.0965 0.3393 

6/23/06 11:50 Mouth/Trial 2 0.1433 0.3400 

6/23/06 12:50 Dam/Trial 1 0.1475 0.2832 

6/23/06 13:15 Dam/Trial 2 0.1194 0.2766 

6/23/06 13:25 Dam/Trial 3 0.1313 0.2797 

The storm sewer monitoring at the intersection of Scollard Drive and Francis Stewart 

Road was completed by City of Peterborough staff. The equipment used in the storm 

sewer was supplied by the City and consisted of a NIVUS Flowmeter 820U. The sewer 




monitoring covered the period from April 19 to June 19, 2006. Figure 4.2.3 shows a 

plot of a typical part of the flow record for that gauge. In addition, the City provided 

rainfall data collected at City Hall (approximately 2.5 km south of Thompson Creek) 

for the period corresponding to the instream flow data. Additional rainfall data was 

also obtained from a gauge located at Trent University also approximately 2.5 km north 

of Thompson Creek (pers. comm. Peter Lafleur, 2006). 

The use of the described data and the impact of its accuracy on the model verification 

process is described in Section 4.4. The complete records for all flow and rainfall 

gauges are included in Appendix G. 

Figure 4.2.1: Locations of Temporary Flow Gauges 




Thompson Creek Mouth Site - Water Levels 

0.54 

0.52 

0.50 

0.48 

0.46 

0.44 

0.42 

0.40 

0.38 

0.36 

0.34 

0.32 

0.30 

0.28 

0.26 

0.24 

0.22 

21- 

Apr-06 

23- 

Apr-06 

25- 

Apr-06 

27- 

Apr-06 

29- 

Apr-06 

1-May- 

06 

3-May- 

06 

5-May- 

06 

7-May- 

06 

9-May- 

06 

11- 

May- 

06 

13- 

May- 

06 

15- 

May- 

06 

17- 

May- 

06 

19- 

May- 

06 

21- 

May- 

06 

23- 

May- 

06 

25- 

May- 

06 

27- 

May- 

06 

29- 

May- 

06 

31- 

May- 

06 

2-Jun- 

06 

4-Jun- 

06 

Figure 4.2.2: Typical Period of Record from Gauge at Mouth of Thompson Creek 

14-06605-01-W01 City of Peterborough 42 

6-Jun- 

06 

Head of Water (m)



4.3 EXISTING DRAINAGE/STORMWATER MANAGEMENT SYSTEM 

A clear understanding of the existing drainage and stormwater management system is 

essential for the development of a detailed flood reduction plan. The following sections 

describe the main elements and presents mapping showing the extent of the existing 

system. 

4.3.1 Thompson Creek Drainage Area 

Drawing No. SS-1 shows the storm sewer system within the Thompson Creek 

watershed. It should be noted that the entire area is serviced by a “separated sewer 

system,” i.e. separate sewers for sanitary wastes and storm runoff. This does not, 

however, eliminate the possibility that cross-connections exist between the systems 

leading to storm runoff occasionally entering the sanitary sewer system. The majority 

of the storm sewer system is owned and operated by the City of Peterborough (some 

local components within condominium developments are privately owned by the 

condominium corporations). Drawing No. SS-1 indicates the outfalls from the system. 

In general, there are three main storm sewer systems within the Thompson Creek 

drainage area: 

i) the system which drains the previously developed phases of the Waverley 

Heights subdivision. This has two outfalls: the larger outfall services all the 

streets east of the intersection of Scollard Drive and Francis Stewart Road and 

outlets into a drainage channel north of the intersection of those two roads. 

This channel will eventually be replaced by a storm sewer extending down to 

the stormwater management pond proposed to be constructed near the creek 

during the next phase of this development. The second outfall services Eldon 

Court and a small piece of Frances Stewart Rd. It discharges to the creek 

through a small stormwater management facility. 

ii) 

iii) 

the system which drains Armour Road into Thompson Creek. This consists of 

several separate pieces of sewer that drain the road north and south of the creek 

and the east and west sides of the road. 

the system which drains Ashdale Crescent East and Ashdale Crescent West into 

the creek. The outfall from this system is just downstream of the box culvert 

which crosses the creek at the north west corner of Ashdale Crescent West. 

These systems will be detailed further in the section describing the OTTSWMM 

modelling of their major/minor system flow characteristics (Section 4.4.3). 




Stormwater management refers to the use of a variety of techniques designed to control 

storm runoff to mitigate its potential negative impacts such as flooding, degradation of 

water quality, channel erosion and damage to the ecological health of natural systems. 

The techniques available are generally either designed to temporarily store runoff to 

reduce its rate of flow and allow settling of suspended particles or to reduce its volume 

by allowing it to soak into the ground or evaporate. Drawing No. SS-1 shows the 

location of one existing stormwater management facility within the Thompson Creek 

watershed at the end of Eldon Court. 

4.3.2 Local Drainage To Otonabee River 

Drawing No. SS-1 also shows the storm sewer system within the local drainage areas 

which discharge directly into the Otonabee River between the southern boundary of the 

Thompson Creek watershed and Parkhill Road East. Again, the storm sewer system is 

a “separated” sewer system. The majority of the system on public lands and rights of 

way is owned by the City. However, several of the developments west and east of 

Armour Road are privately held condominium developments and within them, the 

drainage system is also privately owned. The City does not have responsibility for 

maintaining or upgrading those drainage elements. In general, the City owned 

components are as follows: 

i) the system which drains the area south of the Thomas A. Stewart Secondary 

School including Armour Road, Paddock Wood and Whitaker Street to an 

outfall to the Otonabee River just below the Hydro Dam. 

ii) 

iii) 

iv) 

the system which drains Franmor Drive, Chapel Drive, Dainton Drive, Abbey 

Lane and part of Armour Road to the same outfall to the Otonabee River just 

below the Hydro Dam as for system i). 

the system which drains part of Armour Road south of Moir Street and Moir 

Street itself to an outfall at the end of Moir Street. 

the system which drains part of Spencleys Lane, the south part of Lisburn 

Street, part of Armour Road and Vinette Street to an outfall to the Otonabee 

River at the end of Vinette Street. 

v) the system which drains part of Armour Road and Dunlop Street to an outfall to 

the Otonabee River at the end of Dunlop Street. 

vi) 

the system which drains part of Armour Road and part of Parkhill Road East to 

the Otonabee River near the Parkhill Road bridge. 




These systems will be detailed further in the section describing the OTTSWMM 

modelling of their major/minor system flow characteristics (Section 4.4.3). 

To the best of our knowledge, there are no existing stormwater management facilities 

within this part of the study area. However, there is low area east of Armour Road just 

north of Franmor Drive which may be functioning as a stormwater storage area. 

4.4 MODELLING CHARACTERISTICS OF MAJOR/MINOR SYSTEMS 

As noted above, three different computer modelling tools were used to complete the 

analysis of existing flood vulnerability. The following sections describe first the 

analysis of water course related flood vulnerability then local flood vulnerability. 

4.4.1 OTTHYMO Modelling of Thompson Creek Drainage Area 

The first step in analysing vulnerability to flooding from the Thompson Creek 

watercourse was to estimate the flows carried by the creek under various rainfall events. 

To do this, the Visual OTTHYMO computer model was used. It transforms rainfall 

data into flow estimates using equations which represent the response of the watershed. 

The response is represented by parameters such as the drainage area, watershed slope, 

watershed length, soil characteristics, imperviousness of the surface and initial wetness 

of the basin. Together, these dictate how much runoff will occur for a particular rainfall 

and how fast that runoff will be transformed into flow in the creek. The following 

describes the development of the OTTHYMO model and its verification using 

monitored flow data. 

4.4.1.1 Model Development 

Existing Land Use 

The Thompson Creek watershed was subdivided into four sub-areas to facilitate 

modelling its response under existing land use conditions. Figure 4.4.1 shows the 

drainage boundaries of the sub-areas and their actual drainage areas in hectares. It also 

shows the locations along the creek at which flows were calculated by the model. 

Table 4.4.1 shows the other parameters used in the model to represent existing 

conditions. Documentation of the model is included in Appendix H. This model was 

used to estimate flows for measured rainfall/flow events monitored during the period 

April to June 2006 to verify that the model was a good representation of the watershed 

(see Section 4.4.1.2). However, it was not used to simulate the “design events” to 

investigate flood vulnerability since land use changes are imminent within the 

Thompson Creek watershed. To do so, the existing conditions model was modified to 

represent future land use conditions. 




Future Land Use 

Once the existing conditions model had been verified, the Thompson Creek watershed 

was further subdivided as shown in Figure 4.4.2, to allow for an accurate representation 

of future conditions. The model computes flows at the same locations in the creek but 

uses additional detail to fully represent the changed land use conditions. Table 4.4.2 

shows the parameters used in this version of the model. It should be noted that based 

upon the results of the “Thompson Creek Central Stormwater Management Facility 

Class EA, Environmental Study Report,” it was assumed that the northern boundary of 

Thompson Creek would remain as in the existing conditions model. This is because 

that report recommended diversion of all flows from the proposed development north of 

Thompson Creek to a central stormwater management facility adjacent to the Otonabee 

River. Since the area is currently occupied by a former quarry, its elevation is below 

the creek and currently no storm runoff from the area enters Thompson Creek. Hence 

the proposed stormwater management approach will maintain this situation. 

Documentation of the future conditions model is included in Appendix H. 

Table 4.4.1 

Visual OTTHYMO Model Parameters for Existing Conditions 

Parameter Sub-Catchment 

10 

Sub-Catchment 

11 

Sub-Catchment 

12 

Sub-Catchment 

13 

OTTHYMO NASHYD STANDHYD STANDHYD STANDHYD 

Command 

Drainage Area 15.8 18.5 11.5 18.1 

(ha) 

CN 54 69 69 69 

IA (mm) 6 4 4 4 

N 3 

TP (hr) 0.374 

XIMP 0.20 0.20 0.17 

TIMP 0.26 0.26 0.22 

SLPP (%) 2 2 2 

LGP (m) 40 40 40 

MNP 0.03 0.03 0.03 

DPSI (mm) 0.5 0.5 0.5 

SLPI (%) 1 1 1 

LGI (m) 351.2 276.9 347.4 

MNI 0.013 0.013 0.013 

Abbreviations: CN – SCS Curve Number, IA – Initial Abstraction, N – NASHYD No. of linear 

reservoirs, TP – Time to Peak, XIMP – Directly Connected Imperviousness, TIMP – Total 

Imperviousness, SLPP – Slope of Pervious Area, LGP – Length of Pervious Area, MNP – Manning’s 

roughness of Pervious Area, DPSI – Depression Storage of Impervious Area, SLPI – Slope of 

Impervious Area, LGI – Length of Impervious Area, MNI – Manning’s roughness of Impervious 

Area. 




Subcatchment Command Area 

(ha) 

Table 4.4.2 

Visual OTTHYMO Model Parameters for Future Conditions 

CN IA 

(mm) 

N TP 

(hr) 

XIMP TIMP SLPP 

(%) 

LGP 

(m) 

MNP DPSI 

(mm) 

# 101 NASHYD 8.5 54 6 3 0.320 

# 102 STANDHYD 7.8 69 4 0.35 0.45 2 40 0.03 0.5 1 228 0.013 

# 103 STANDHYD 1.45 69 4 0.05 0.2 2 40 0.03 0.5 1 98 0.013 

# 104 STANDHYD 1.2 69 4 0.05 0.2 2 40 0.03 0.5 1 89 0.013 

Sub-Total 18.95 

# 111 NASHYD 3.6 69 4 3 0.315 

# 112 STANDHYD 15.28 69 4 0.35 0.45 2 40 0.03 0.5 1 319 0.013 

# 113 STANDHYD 0.49 69 4 0.05 0.3 2 40 0.03 0.5 1 57 0.013 


# 121 NASHYD 4.2 69 4 3 0.328 

# 122 STANDHYD 4.5 69 4 0.2 0.3 2 40 0.03 0.5 1 173 0.013 

# 123 STANDHYD 1.7 69 4 0.35 0.45 2 40 0.03 0.5 1 106 0.013 


# 131 NASHYD 8.8 69 4 3 0.394 

# 132 STANDHYD 8.8 69 4 0.35 0.45 2 40 0.03 0.5 1 242 0.013 

Sub-Total 17.6 69 4 

SLPI 

(%) 

LGI 

(m) 

MNI 

Total 66.32 

Abbreviations: CN – SCS Curve Number, IA – Initial Abstraction, N – NASHYD No. of linear reservoirs, TP – Time to Peak, XIMP – Directly Connected 

Imperviousness, TIMP – Total Imperviousness, SLPP – Slope of Pervious Area, LGP – Length of Pervious Area, MNP – Manning’s roughness of Pervious Area, 

DPSI – Depression Storage of Impervious Area, SLPI – Slope of Impervious Area, LGI – Length of Impervious Area, MNI – Manning’s roughness of 

Impervious Area. 




4.4.1.2 Model Verification 

Model verification consisted of simulating the flows from a measured rainfall event 

from the monitoring period and comparing the results with measured flows in the creek 

and at the outlet from the storm sewer system at the intersection of Scollard Drive and 

Francis Stewart Road. The event selected occurred at about 2:00 am on June 1, 2006. 

According to the rainfall gauge located at City Hall, about 30 mm of rainfall fell in 

about 3 hours. This is approximately a 1 in 2 year rainfall for that duration. In contrast, 

the rainfall gauge at Trent University (about 2.5 km north of the area) recorded only 

about 4 mm of rain. At the outlet from the sewer system, a flow of 0.75 m 3 /s was 

recorded. This is theoretically at or slightly above the capacity of the outlet pipe at that 

location. Hence this was a significant event which produced a runoff volume of about 

22 mm that is consistent with the observed rainfall at City Hall. The storm must have 

been a localized event which passed through downtown and the study area but did not 

reach as far north as the University. Hence the City Hall rainfall was used in the 

simulation. Interestingly, as previously discussed in Section 4.2.3, the flow recorded at 

the instream gauge near the corner of Ashdale Crescent West was only about 0.3 m 3 /s. 

Theoretically, the flow downstream should be greater than upstream given the greater 

drainage area. However, there appears to be significant overbank storage in the area 

upstream of Armour Road (see for example, the discussion on Reach No. 2 in Section 

4.2.3) which reduces the downstream flows. A similar “damped” response was 

observed at this gauge for all other significant rainfalls during the monitoring period. 

Only the normal seepage of flow through the Thompson Creek Dam was measured at 

the upstream gauge, i.e. no flow spilled over the stop logs in the dam. 

The results of the simulation of the verification event are summarized in Table 4.4.3. 

As indicated, the outflow from subcatchment 11, is equivalent to the outflow from the 

Scollard/Francis Stewart outfall flow. The observed and simulated flows match very 

closely. The flow at the downstream gauge point also matches closely since a storage 

element was added to the model just upstream of Armour Road. This required about 

1,900 m 3 of storage. A review of the overbank topography in the area indicated that 

this amount of storage is available in the riparian area and its utilization would be 

promoted by the presence of a number of small dam structures which obstruct the creek. 

The model output is included in Appendix G. 

Based upon this close correspondence of observed and simulated flows for this 

significant event, the model was judged to satisfactorily represent the hydrologic 

response of Thompson Creek. The model parameters adopted were those originally 

estimated from the physiographic data as shown in Tables 4.4.1 and 4.4.2. No other 

flows of significance were found in the flow record from the gauge near the outlet of 




Thompson Creek due to the damping effect of the storage upstream of Armour Road. 

Hence only the one event was used in the verification process. 

Table 4.4.3 

Comparison of Observed and Simulated Flows for June 1, 2006 Event 

Location 

Rainfall 

(mm) 

Observed 

Flow (m 3 /s) 

Simulated 

Flow (m 3 /s) 

Scollard/Francis Stewart Sewer Outlet 29.3 0.75 0.78 

Thompson Creek near Ashdale Cresc. W. 29.3 0.30 0.29 

4.4.2 HEC-RAS Modelling of Thompson Creek 

The HEC-RAS model calculates water levels in a creek and its flood plain 

corresponding to a set of flows. It uses information on the shape, length and roughness 

of the creek and flood plain and on the size of any culverts, bridges, dams, etc. which 

cross the creek. The following describes the development of the Thompson Creek 

HEC-RAS model. 


As discussed in Section 4.2.2, the Otonabee Region Conservation Authority (ORCA) 

developed flood plain mapping of Thompson Creek some years ago using an earlier 

version of HEC-RAS known as HEC-2. Since the existing model was developed prior 

to installation of several of the culverts at the downstream end of the creek, it required a 

complete review, update and conversion. The existing model was provided to MMM 

and was used as a general basis for a new model. In general, the locations of the crosssections 

used are in similar locations but all have been recoded based on current 

topographic information, detailed field surveys of the low flow channel and current data 

on the water crossings (four sets of culverts from the outlet to Armour Road). Drawing 

FV-1 shows the location and extent of the cross-sections used. The field survey notes 

and cross-section plots are included in Appendix I. The model coding is also presented 

in Appendix I. 


Ideally, verification of the HEC-RAS model would involve comparing computed water 

levels with observed levels along the creek for a significant storm event. Unfortunately, 

only limited water level data is available for Thompson Creek. For the event of 

June 1, 2006, used to verify the hydrologic models, a water level measurement was 

available at the downstream flow gauge near Ashdale Crescent West. This indicated 




that the gauge level rose by about 5 cm during the event (although the rainfall was 

approximately a 1 in 2 year storm). The simulation with HEC-RAS using the 

OTTHYMO generated flows (including the storage upstream of Armour Road) was 

able to reproduce the observed water level at the gauge. The summary output for the 

event in included in Appendix I. 

For the event of July 14 – 15, 2004, it was anticipated that some post-storm high water 

marks might be available with which to verify the HEC-RAS model. However, as 

indicated by ORCA in the “Thompson Creek Management Plan” (2004), there was 

relatively little impact of the storm on Thompson Creek itself. There were some reports 

of local drainage issues (at Scollard Drive, Eldon Court, Riverpark Village – see 

Appendix B) but no information indicating flooding from the creek itself or of water 

levels observed. City employees recollected that the culvert at Armour Road may have 

overtopped for a short time. Simulations of the flows and water levels for the event 

indicated that levels would have been similar to those for a Regional Storm and Armour 

Road would have overtopped. The summary output from HEC-RAS is included in 

Appendix I. Based upon this limited evidence, it was concluded that the HEC-RAS 

model satisfactorily computes water levels in Thompson Creek. 

4.4.3 OTTSWMM Modelling of Local Drainage Systems 

As discussed in Section 4.3, within the study area, there are three local drainage 

systems which outlet directly into Thompson Creek and a further six local systems 

which drain directly into the Otonabee River. Each of these was modelled using the 

OTTSWMM model. This tool has the ability to calculate both “major” and “minor” 

system flows based upon a description of the drainage areas, street layout/width and 

storm sewer systems. The “major” system flows are those which travel overland along 

the streets, over parking lots, down grassed channels, etc. The “minor” system flows 

are those which are contained in the sewer pipes. The model uses a hydraulic 

description of the catchbasins in the system to determine how much of the flow is 

actually “captured” by the sewer system and how much remains upon the streets, etc. 

This allows analysis of whether the pipes are full or not and of the depth of flow on the 

streets and in other overland flow routes throughout the system. Appendix J includes 

information on the methods used by OTTSWMM to calculate major/minor flows. 


Drawing No. SS-1 shows the drainage plan, sewer system elements and major system 

elements used to create the OTTSWMM models of the eight separate local drainage 

systems in the study area. The details of the models are presented in a series of tables 

included in Appendix J. The tables include: 




J-1 Minor system data and connectivity – Thompson Creek systems 

J-2 Listing of major/minor system outlets – Thompson Creek systems 

J-3 Major system data and connectivity – Thompson Creek systems 

J-4 Major system rating curves – Thompson Creek systems 

J-5 Catchbasin capture curves – Thompson Creek systems 

J-6 Subcatchment data – Thompson Creek systems 

J-7 Minor system data & connectivity – Otonabee River local drainage systems 

J-8 Listing of major/minor system outlets – Otonabee River local drainage systems 

J-9 Major system data and connectivity – Otonabee River local drainage systems 

J-10 Major system rating curves – Otonabee River local drainage systems 

J-11 Catchbasin capture curves – Otonabee River local drainage systems 

J-12 Subcatchment data – Otonabee River local drainage systems 

This data was obtained from the City’s Geographic Information System and Sewer 

Database and was verified and supplemented as necessary through detailed field 

surveys. In general, the field survey provided information on missing sewer inverts or 

pipe sizes. Detailed information is provided in Appendix J-13. 


Model verification consisted of simulating the flows from three measured rainfall 

events from the monitoring period and comparing the results with measured flows at the 

outlet from the storm sewer system at the intersection of Scollard Drive and Francis 

Stewart Road. Of the eight local systems within the study area, this was the one system 

chosen for monitoring. The events selected were the three largest recorded flows in the 

April to June 2006 period. They included the same event as used for the OTTHYMO 

model i.e. a storm which occurred at about 2:00 am on June 1, 2006. As previously 

discussed, it was approximately a 1 in 2 year rainfall for its three hour duration. Hence 

this was a significant event upon which to base the model verification. At the sewer 

system outlet, the 3 events had flows of 0.32 m 3 /s, 0.18 m 3 /s and 0.76 m 3 /s respectively. 

The recorded rainfalls for the three events at the City Hall gauge were input to the 

OTTSWMM model of the Scollard Drive/Francis Stewart Road system and the 

resulting flows estimated. City Hall data was used since it is recorded in 5 minute 

intervals whereas the Trent University data is only recorded in 30 minute increments. 

Table 4.4.4 compares the observed and simulated peak flows for the three events. 

Figure 4.4.3 shows the observed and simulated hydrographs for the June 1, 2006 event. 




As indicated, the modelled and observed results agree well and the model can be 

considered to be an accurate representation of the system. As with the OTTHYMO 

model, the model parameters adopted for design simulations were those originally 

estimated from the physiographic data. Since the other systems in the study area are 

within close proximity of the verified area and have similar characteristics, it was 

concluded that OTTSWMM models developed using similar parameters and procedures 

would also be satisfactory representations of those systems. 

Table 4.4.4 

Comparison of Observed and Simulated Peak Flows OTTSWMM 

Date of Event 

Observed Rainfall 

(City Hall/Trent U.) 

(mm) 

Observed Peak 

Flow (m 3 /s) 

Simulated Peak 

Flow (m 3 /s) 

May 13, 2006 12.0 / 11.5 0.32 0.23 

May 15 – 16, 2006 13.4 / 13.7 0.18 0.16 

June 1, 2006 29.6 / 4.0 0.76 0.54 




Figure 4.4.3: Comparison of Observed and Simulated Flows 

Scollard Dr./Frances Stewart Rd. Storm Sewer June 1st, 2006 

1.2 

1 

0.8 

0.6 

Flow Rate (c.m.s) 

Prec. Depth (mm) 

0.4 

0.2 

0 

2:10 2:15 2:20 2:25 2:30 2:35 2:40 2:45 2:50 2:55 3:00 3:05 3:10 3:15 3:20 3:25 3:30 3:35 3:40 3:45 3:50 3:55 4:00 4:05 4:10 4:15 4:20 4:25 4:30 4:35 4:40 4:45 4:50 4:55 

Time 

Rainfall at Cityhall Flow at Storm outlet (Frances Stewart/Scollard) OTTSWMM_Sewer OTTSWMM_Overland OTTSWMM Total Creek Wl Delta 

14-06605-01-W01 City of Peterborough 53 

0 

2 

4 

6 

8 

10 

12 

14



4.5 SIMULATION OF FLOOD VULNERABILITY DESIGN EVENTS 

Based upon the city-wide “Flood Reduction Master Plan,” the overall Terms of 

Reference for the “Detailed Flood Reduction Studies” were developed. These defined 

an overall set of storm events which were to be used during the detailed studies to 

evaluate flood vulnerability. These “design rainfalls” were selected to: simulate 

conditions as they occurred during the July 2004 storm, address mapping of flood 

plains and overland flow routes and provide a basis for flood damage estimation. Each 

rainfall was simulated with the three models described above to calculate flows, water 

levels and extent of flooding. The following sections describe this process. 

4.5.1 Definition of Design Rainfalls 

As noted, the “design rainfalls” fall into three groups: 

 

 

 

the actual storm of July 14 -15, 2004 which led to such extensive flooding 

a set of storms with pre-defined total rainfall volumes (40mm, 60mm, 80mm, 

100mm, 120mm and 193mm) to be used for mapping the extent of flood plains 

and overland flow spills routes 

a set of storms with specific return periods (1 in 2 year, 1 in 5 year, 1 in 10 year, 

1 in 25 year, 1in 50 year and 1 in 100 year) to be used to evaluate the numerical 

value of average annual flood damages. This is required as part of the benefitcost 

evaluation of any proposed remedial measures. 

The following sections describe in detail the storms used based upon discussions held 

between City staff, MMM and consultants for the parallel detailed flood reduction 

studies underway on other City watersheds (see Appendix K for documentation). 

4.5.1.1 Peterborough Storm of July 14 - 15, 2004 

Given the significance of the July 2004 storm, a detailed investigation of its 

characteristics was commissioned by ORCA. This report was summarized in Section 

3.2.1 and the general characteristics of the storm were described. Based upon that 

initial analysis, a detailed temporal-spatial analysis of the storm was completed by 

UMA-AECON (2006) (see Appendix K for summary report). This analysis was 

completed to permit the best estimate of the storm’s rainfall volume – time distribution 

(hyetograph) over any particular watershed within the City to be computed. 

Information from that report was initially used to define a hyetograph for the Thompson 

Creek study area. Figure 4.5.1 shows the study area boundary overlaid upon a map of 

the total rainfall distribution from the radar analysis across the study area. 







On average the total rainfall was estimated to be 133.9 mm. However, when this was 

compared to a number of other rainfall measurements in the area (i.e. Trent University 

and several unofficial gauges, e.g. buckets), it was found that the average rainfall was 

significantly higher than estimated from the radar. As indicated on Figure 4.5.2, the 

estimated average was 233 mm. Since the local measurements provided only total 

amounts, the time distribution of the rainfall was based upon the radar time distribution. 

The resulting rainfall hyetograph in ten minute intervals is shown in Figure 4.5.3. This 

rainfall hyetograph was used to simulate the response of Thompson Creek and the local 

areas draining to the Otonabee River to the July 2004 storm. Due to the very small 

drainage area, a single hyetograph was used as opposed to multiple hyetographs to 

represent areal rainfall distribution over larger areas. 

Figure 4.5.3: Peterborough Rainfall July 14/15 2006 

9.00 

8.00 

7.00 

Rainfall (mm) 

6.00 

5.00 

4.00 

3.00 

2.00 

1.00 

0.00 

0 200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 

Time (10 min steps) 

Rain (mm) 

4.5.1.2 Volume Events for Flood Vulnerability Mapping 

As noted above, the Terms of Reference prescribed a set of rainfall events of fixed total 

volume for the purposes of mapping flood limits. These were: 

Level 1: 40mm event 









In order to use these rainfall volumes in the hydrologic models (OTTHYMO and 

OTTSWMM), they had to be transformed into volume-time distributions (hyetographs) 

as in the case of the July 2004 storm. To do this, it was agreed that a rainfall 

distribution pattern developed by Canada’s Atmospheric Environment Service (AES) 

would be used. This distribution, known colloquially as the “AES distribution,” was 

prepared by that federal agency by analysing the hyetographs of historical storms across 

Canada. Different distributions are available for each part of the country since storm 

types vary by location. Different distributions are also available depending upon the 

duration of the storm required. It was agreed (see Appendix K) that the 6 hour 

distribution would be the primary choice for the detailed flood reduction studies but that 

the 1 hour and 12 hour distributions would also be considered to determine which was 

most critical. The critical duration of a design storm depends upon the size of the 

watershed to which it is being applied. In the case of the Thompson Creek study area, 

the drainage area is relatively small (approximately 200 hectares). Hence it was 

anticipated that either the 1 hour or 6 hour distribution would be appropriate. Figure 

4.5.4 shows typical hyetographs for the 1 hour and 6 hour storms (based upon the 120 

mm event). It should be noted that the 193 mm event is actually the “Regional Storm” 

currently in use in the Peterborough area. It is based upon a historical event which 

occurred in Timmins, Ontario and has its own prescribed hyetograph shape. This is 

also shown on Figure 4.5.4. The six design storms used for flood limit mapping were 

based upon these patterns with the actual amounts adjusted to reflect the required totals. 

The actual amounts are tabulated in Appendix K. 

Figure 4.5.4: Hyetographs for Selected Rainfalls 

30 

25 

Rain (mm) 

20 

15 

10 

5 

0 

30 

60 

90 

0 

120 

150 

180 

210 

240 

270 

300 

330 

Time (min) 

360 

390 

420 

450 

480 

510 

540 

570 

600 

630 

660 

690 

720 

120 mm AES Type 2 (6 hr) 120 mm AES Type 2 (1hr) 193 mm - Timmins (12 hr) 100 Year AES Type 2 (6hr) 




4.5.1.3 Return Period Events for Flood Damage Estimation 

For the purpose of estimating average annual flood damages, it is necessary to calculate 

flood damages for events with a known probability. To facilitate this, flows and water 

levels must be calculated for events of known probability (or equivalently return 

period). Hence a series of rainfalls with return periods of 1 in 2 years, 1 in 5 years, 1 in 

10 years, 1 in 25 years, 1in 50 years and 1 in 100 years were required. The rainfall 

volumes for these events were derived from the intensity-duration-frequency (i-d-f) 

curves from the Peterborough Airport since it has the longest period of record in the 

area. Table 4.5.1 shows the total rainfall amounts (mm) for one and six hour durations 

for the noted return periods. In order to simulate the required hydrographs with the 

hydrologic models described earlier, a hyeotograph (volume-time distribution) was 

required for each event. As in the case of the volume events discussed above, the “AES 

distribution” was used for both the one and six hour distribution. The 1 in 100 year six 

hour storm is shown on Figure 4.5.4. The actual rainfall amounts used for each storm 

are tabulated in Appendix K. 

Table 4.5.1 

Total Rainfall Volumes for 1 hour and 6 Hour Storms (Peterborough Airport) 

Return Period 

6 Hour 

Volume 

(mm) 

1 Hour 

Volume 

(mm) 

2 Year 37.36 23.75 

5 Year 48.65 32.26 

10 Year 57.49 38.96 

25 Year 65.65 45.53 

50 Year 76.13 51.66 

100 Year 81.73 56.25 

4.5.2 Results of Thompson Creek Watercourse Simulations 

The results of the Visual OTTHYMO and HEC-RAS simulations for the Thompson 

Creek watercourse are described in the following sections. 


Table 4.5.2 shows the calculated peak flows for Thompson Creek for future land use 

conditions (described in Section 4.4.1.1) for the six return period events (1 in 2 year to 

1 in 100 year) for the six hour AES storm distribution at the locations on the creek 

indicated on Figure 4.4.2. It should be noted that a constant outflow of 0.1 m 3 /s was 

assumed from the Thompson Creek Dam based upon the flow measurements taken 

during the study. The model includes the proposed Waverly Heights SWM pond which 

attenuates flows from that subdivision before they discharge to Thompson Creek. 

However, it does not include the flood plain storage upstream of Armour Road. 




Table 4.5.2 

Peak Flows for Thompson Creek for 6 Hour AES Return Period Storms 

Location 

Area 

(ha) 

Peak Runoff Rate (m 3 /s) 

2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 

#1 (Thompson Dam) 0 0.100 0.100 0.100 0.100 0.100 0.100 

#2 (Pond Outlet) 11.15 0.168 0.219 0.267 0.315 0.385 0.426 

#3 (Proposed Crossing) 38.32 0.333 0.490 0.630 0.813 1.044 1.170 

#4 (Armour Road) 48.72 0.430 0.657 0.831 1.055 1.365 1.526 

#5 (Otonabee River) 66.32 0.620 0.954 1.227 1.517 1.917 2.156 

Table 4.5.3 shows the peak flows at the same locations for the one hour AES storm . 

Table 4.5.3 

Peak Flows for Thompson Creek for 1 Hour AES Return Period Storms 

Location 

Area 

(ha) 

Peak Runoff Rate (m 3 /s) 

2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 

#1 (Thompson Dam) 0 0.100 0.100 0.100 0.100 0.100 0.100 

#2 (Pond Outlet) 11.15 0.173 0.255 0.334 0.424 0.514 0.588 

#3 (Proposed Crossing) 38.32 0.301 0.504 0.697 0.930 1.201 1.414 

#4 (Armour Road) 48.72 0.363 0.633 0.915 1.194 1.547 1.824 

#5 (Otonabee River) 66.32 0.699 1.137 1.530 1.973 2.372 2.721 

As indicated by the tables, the one hour distribution generates the highest peak flow at 

all locations for all return periods. Hence these flows (as indicated in Table 4.5.3) were 

adopted as the “design flows” for the return period events for Thompson Creek. 

Detailed simulation outputs from Visual OTTHYMO are included in Appendix H. 

The calculated peak flows were input to the HEC-RAS model of Thompson Creek to 

calculate the corresponding water levels. Table 4.5.4 shows the water levels for the 1 in 

100 year storm. Mapping of the corresponding flood line is described in Section 4.6.1. 

Water levels for the 1 in 2 year to 1 in 50 year storms (which are all less than those 

indicated in Table 4.5.4) are presented in Appendix I with the HEC-RAS outputs. 


Table 4.5.5 shows the calculated peak flows for Thompson Creek for future land use 

conditions (described in Section 4.4.1.1) for the six volume based events required by 

the Terms of Reference. Flows are indicated for the one hour AES storms at the 

locations on the creek indicated on Figure 4.4.2. The one hour storm was found to give 

the highest set of peak flows. A comparison between Tables 4.5.3 and 4.5.5 shows that 

the peak flows from this set of events exceed the 1 in 100 year peak flow for all storm 

with a volume of 60 mm or more and that the 120 mm storm generates peak flows 




which are almost three times the 1 in 100 year storm event. This is not surprising as the 

1 in 100 year rainfall for a one hour duration is 56.25 mm. 

The final member of the specified event volume rainfall set was the 193 mm storm. 

This is the Regional Storm for the Peterborough area known as the Timmins Storm. It 

was simulated using the Visual OTTHYMO model for two future land use conditions: 

with the proposed Waverley Heights SWM facility in place and without the SWM 

facility in place. The latter represents the case which is used to define a regulatory 

flood line where storage must be ignored according to provincial flood plain policy. 

Table 4.5.4 

Water Levels for Thompson Creek for 1 Hour AES 100 Year Storm 

Cross Section # 

Flow 

(m 3 /s) 

Channel Bottom 

Elev. (m) 

Water Surface 

Elev. (m) 

Water Depth 

(m) 

1623.3 0.10 209.93 210.00 0.07 

1601.3 0.10 209.85 209.93 0.08 

1557.3 0.10 209.36 209.39 0.03 

1433.3 0.10 208.50 208.57 0.07 

1309.3 0.20 208.50 208.56 0.06 

1185.3 0.39 208.50 208.53 0.03 

1061.3 0.59 207.21 207.33 0.12 

927.3 1.41 206.54 206.95 0.41 

791.3 1.41 205.97 206.29 0.32 

588.3 1.82 205.23 205.98 0.75 

579.3 1.82 205.08 205.99 0.91 

577.3 1.82 205.08 205.89 0.81 

Bridge S-3015 

526.0 1.82 204.93 205.82 0.89 

518.0 1.82 204.91 205.83 0.92 

412.0 1.82 204.87 205.48 0.61 

355.0 1.82 204.47 205.17 0.70 

283.0 1.82 204.41 205.14 0.73 

273.0 1.82 204.30 205.13 0.83 

270.0 1.82 204.30 205.09 0.79 

Bridge S-3010 

260.0 1.82 204.30 205.03 0.73 

248.0 1.82 204.28 205.06 0.78 

239.0 1.82 204.28 205.05 0.77 

199.0 1.82 204.27 205.04 0.77 

196.0 1.82 204.27 204.83 0.56 

Bridge S-3005 

186.0 1.82 204.15 204.79 0.64 

170.0 1.82 204.13 204.79 0.66 

113.0 1.82 203.95 204.77 0.82 

20.0 1.82 203.82 204.77 0.95 

17.0 1.82 203.81 204.69 0.88 

Bridge S-3000 

9.0 1.82 203.66 204.20 0.54 

0.0 2.72 203.48 203.88 0.40 




Table 4.5.5 

Peak Flows for Thompson Creek for 1 Hour AES Volume Based Storms 

Location Area 40mm 60mm 80mm 100mm 120mm 

(ha) 

#1 (Thompson Dam) 0 0.100 0.100 0.100 0.100 0.100 

#2 (Pond Outlet) 11.15 0.347 0.652 1.021 1.450 1.897 

#3 (Proposed Crossing) 38.32 0.729 1.585 2.507 3.654 4.857 

#4 (Armour Road) 48.72 0.956 2.059 3.321 4.863 6.313 

#5 (Otonabee River) 66.32 1.597 2.980 4.624 6.790 9.040 

The former case was simulated to give a direct comparison to the other volume based 

storm events and the return period events. Table 4.5.6 presents the resulting peak flows 

for Thompson Creek for the 193 mm storm. 

Table 4.5.6 

Peak Flows for Thompson Creek for 193 mm (Timmins) Storm 

Location 

Area 

(ha) 

Peak Runoff Rate 

(m 3 /s) 

193 mm 

Storm 

With 

SWM 

Pond 

193 mm 

Storm 

Without 

SWM 

Pond 

#1 (Thompson Dam) 0 0.100 0.100 

#2 (Pond Outlet) 11.15 0.648 0.648 

#3 (Proposed Crossing) 38.32 1.852 3.138 

#4 (Armour Road) 48.72 2.533 3.917 

#5 (Otonabee River) 66.32 3.612 5.043 

The calculated peak flows from the volume based events were input to the HEC-RAS 

model of Thompson Creek to calculate the corresponding water levels. Table 4.5.7 

shows the water levels for the 120 mm storm and the 193 mm (Timmins Storm). 

Mapping of the corresponding flood line is described in Section 4.6.1. Water levels for 

the 40 mm to 100 mm storms (which are all less than those indicated in Table 4.5.7 for 

the 120 mm storm) are presented in Appendix I with the HEC-RAS outputs. 

4.5.2.3 Peterborough Storm of July 14 - 15, 2004 

Table 4.5.8 shows the peak flows simulated with Visual OTTHYMO for the July 2004 

Peterborough Storm rainfall amount estimated to have occurred over the Thompson 

Creek watershed (see Section 4.5.1.1). As indicated, peaks resulting from the estimated 

total rainfall of 233 mm are very similar to those for the Timmins Storm. Both are long 

duration, high volume but relatively low peak intensity storms. The calculated peak 




Cross 

Section # 

flows from the July 2004 storm were input to the HEC-RAS model of Thompson Creek 

to calculate the corresponding water levels. Table 4.5.9 shows the resulting water 

levels. Comparing with Tables 4.5.9 and 4.5.7 indicates that the water levels are almost 

identical to those for the Timmins Storm. The corresponding HEC-RAS output is 

included in Appendix I. 

Table 4.5.7 

Water Levels for Thompson Creek for 120 mm Storm and Timmins Storm 

Flow 

(m 3 /s) 

120 mm 1 Hour AES Design Storm Timmins Regional Storm (193 mm) 

Channel 

Bottom 

Elev. (m) 

Water 

Surface 

Elev. (m) 

Water 

Depth 

(m) 

Flow 

(m 3 /s) 

Channel 

Bottom 

Elev. (m) 

Water 

Surface 

Elev. (m) 

Water 

Depth 

(m) 

1623.3 0.10 209.93 210.00 0.07 0.10 209.93 210.00 0.07 

1601.3 0.10 209.85 209.93 0.08 0.10 209.85 209.93 0.08 

1557.3 0.10 209.36 209.39 0.03 0.10 209.36 209.39 0.03 

1433.3 0.10 208.50 208.61 0.11 0.10 208.50 208.57 0.07 

1309.3 0.63 208.50 208.60 0.10 0.22 208.50 208.56 0.06 

1185.3 1.26 208.50 208.52 0.02 0.43 208.50 208.51 0.01 

1061.3 1.90 207.21 207.60 0.39 0.65 207.21 207.44 0.23 

927.3 4.86 206.54 207.07 0.53 3.14 206.54 207.05 0.51 

791.3 4.86 205.97 206.93 0.96 3.14 205.97 206.55 0.58 

588.3 6.31 205.23 206.92 1.69 3.92 205.23 206.52 1.29 

579.3 6.31 205.08 206.92 1.84 3.92 205.08 206.53 1.45 

577.3 6.31 205.08 206.57 1.49 3.92 205.08 206.34 1.26 

Bridge 

S-3015 

526.0 6.31 204.93 206.03 1.10 3.92 204.93 205.93 1.00 

518.0 6.31 204.91 206.13 1.22 3.92 204.91 206.03 1.12 

412.0 6.31 204.87 205.97 1.10 3.92 204.87 205.65 0.78 

355.0 6.31 204.47 205.96 1.49 3.92 204.47 205.57 1.10 

283.0 6.31 204.41 205.94 1.53 3.92 204.41 205.55 1.14 

273.0 6.31 204.30 205.94 1.64 3.92 204.30 205.54 1.24 

270.0 6.31 204.30 205.81 1.51 3.92 204.30 205.46 1.16 

Bridge 

S-3010 

260.0 6.31 204.30 205.67 1.37 3.92 204.30 205.36 1.06 

248.0 6.31 204.28 205.75 1.47 3.92 204.28 205.41 1.13 

239.0 6.31 204.28 205.75 1.47 3.92 204.28 205.41 1.13 

199.0 6.31 204.27 205.75 1.48 3.92 204.27 205.40 1.13 

196.0 6.31 204.27 205.40 1.13 3.92 204.27 205.05 0.78 

Bridge 

S-3005 

186.0 6.31 204.15 205.43 1.28 3.92 204.15 205.12 0.97 

170.0 6.31 204.13 205.51 1.38 3.92 204.13 205.16 1.03 

113.0 6.31 203.95 205.50 1.55 3.92 203.95 205.15 1.20 

20.0 6.31 203.82 205.50 1.68 3.92 203.82 205.15 1.33 

17.0 6.31 203.81 204.88 1.07 3.92 203.81 204.94 1.13 

Bridge 

S-3000 

9.0 6.31 203.66 204.73 1.07 3.92 203.66 204.48 0.82 

0.0 9.04 203.48 204.15 0.67 5.04 203.48 204.00 0.52 




Table 4.5.8 

Peak Flows for Thompson Creek for July 2004 Storm 

Location 

Area 

(ha) 

Peak 

Runoff 

Rate 

(m 3 /s) 

#1 (Thompson Dam) 0 0.10 

#2 (Pond Outlet) 11.15 0.85 

#3 (Proposed Crossing) 38.32 2.82 

#4 (Armour Road) 48.72 3.73 

#5 (Otonabee River) 66.32 5.24 

Cross Section # 

Table 4.5.9 

Water Levels for Thompson Creek for July 2004 Storm 

Flow 

(m 3 /s) 

Channel Bottom 

Elev. (m) 

Water Surface 

Elev. (m) 

Water Depth 

(m) 

1623.3 0.10 209.93 210 0.07 

1601.3 0.10 209.85 209.93 0.08 

1557.3 0.10 209.36 209.39 0.03 

1433.3 0.10 208.50 208.58 0.08 

1309.3 0.12 208.50 208.57 0.07 

1185.3 0.25 208.50 208.51 0.01 

1061.3 0.37 207.21 207.44 0.23 

927.3 1.27 206.54 207.03 0.49 

791.3 1.27 205.97 206.51 0.54 

588.3 1.70 205.23 206.48 1.25 

579.3 1.70 205.08 206.48 1.40 

577.3 1.70 205.08 206.3 1.22 

Bridge S-3015 

526.0 1.70 204.93 205.93 1.00 

518.0 1.70 204.91 206.02 1.11 

412.0 1.70 204.87 205.64 0.77 

355.0 1.70 204.47 205.54 1.07 

283.0 1.70 204.41 205.51 1.00 

273.0 1.70 204.30 205.51 1.21 

270.0 1.70 204.30 205.43 1.13 

Bridge S-3010 

260.0 1.70 204.30 205.34 1.04 

248.0 1.70 204.28 205.39 1.11 

239.0 1.70 204.28 205.39 1.11 

199.0 1.70 204.27 205.38 1.11 

196.0 1.70 204.27 205.03 0.76 

Bridge S-3005 

186.0 1.70 204.15 205.12 0.97 

170.0 1.70 204.13 205.15 1.02 

113.0 1.70 203.95 205.15 1.30 

20.0 1.70 203.82 205.15 1.33 

17.0 1.70 203.81 204.96 1.15 

Bridge S-3000 

9.0 1.70 203.66 204.45 0.79 

0.0 2.42 203.48 204.01 0.53 




4.5.2.4 Thompson Creek Dam Flows 

All the storm event simulations previously described assumed a typical constant 

baseflow seepage rate of 0.1 m 3 /s from the Thompson Creek Dam. This is an 

appropriate assumption when dealing with local storms centred over the relatively small 

Thompson Creek watershed (approximately 75 hectares). The Thompson Bay on the 

upstream side of the dam is fed by the Otonabee River which has a drainage area in 

excess of 7,500 km 2 . At the time of year when local high intensity storms would occur, 

the Otonabee River would generally be at low levels and any local storm would have no 

effect on its flows. Hence it is unlikely that a large flow would occur at the dam 

simultaneously with the local flow in the Thompson Creek watershed. 

On the other hand, however, there is a potential flood risk in the Thompson Creek 

watershed from a release of water from the Thompson Creek Dam itself. This could 

occur for a number of reasons, such as: 

 

 

 

high water levels on the Otonabee River during an extreme event might overtop 

the dam and cause high flows in Thompson Creek 

during high flow periods on the Otonabee River, the Trent Severn Waterway 

(TSW), operators of the dam, may be forced to open the dam by removing some 

of the stop logs to release flow from Thompson Bay down Thompson Creek 

under extreme conditions, a dam break might occur which would release high 

flows down Thompson Creek. There is no evidence that such an occurrence is 

likely to happen but it is a potential scenario which should be considered. 

It is not feasible to predict the probability of the above events because they involve 

various human interventions which may or may not occur in different circumstances. 

However, in order to understand the implications of such situations, two simulations 

were completed to identify the flows which might occur in Thompson Creek and the 

possible water levels and extent of flooding that might occur. The first scenario 

involved removing 3 stop logs from the dam. This might be equivalent to the second 

type of situation described above. The second scenario involved removing 7 stop logs 

from the dam. This might be considered to be equivalent to the third situation where a 

breach of the dam occurred. In both cases there would be a sudden release of water 

from the dam with the latter being much larger. 

The Visual OTTHYMO model was used to simulate the flows which would occur in 

Thompson Creek in these two situations. It was assumed that the water level in 

Thompson Bay would remain constant since there is a large volume of water in that 

system. This effectively generates a constant outflow which is then routed downstream. 




The resulting flows were then input to the HEC-RAS model of Thompson Creek to 

calculate the associated water levels. This steady state simulation is not a full 

simulation of the effect of a flood wave as that type of dynamic routing is beyond the 

scope of the current study. However, it does provide an indication of the potential 

extent of flooding that might occur. 

Table 4.5.10 shows the simulated flows along Thompson Creek for the two scenarios. 

Table 4.5.11 shows the resulting water levels. As indicated, in comparison to 

Tables 4.5.3, 4.5.5, 4.5.6 and 4.5.8, the flows generated by releases from the Thompson 

Creek Dam could be significantly higher than any of the other rain storm related events 

considered. Similarly, the resulting water levels would exceed those for any of the 

rainfall related events centred directly over Thompson Creek. The extent of flooding 

which could potentially occur is discussed in Section 4.6.1 where the mapping of the 

extent of the flood plain is described. 

Table 4.5.10 

Peak Flows for Thompson Creek for Releases from Thompson Bay Dam 

Location 

Area 

(ha) 

Peak Runoff Rate 

(m 3 /s) 

3 Logs 7 Logs 

Removed Removed 

#1 (Thompson Dam) 0 15.70 43.60 

#2 (Pond Outlet) 11.15 15.76 43.66 

#3 (Proposed Crossing) 38.32 15.89 43.79 

#4 (Armour Road) 48.72 15.86 43.78 

#5 (Otonabee River) 66.32 15.90 43.80 

4.5.3 Results of Local Drainage Systems Simulations 

The results of the OTTSWMM simulations of the local drainage systems in the 

Thompson Creek watershed and the areas which drain directly to the Otonabee River 

are described in the following sections. 


The verified OTTSWMM models of the local drainage systems in the Thompson Creek 

study area (discussed in Section 4.4.3) were used to simulate the 1 in 2 year through 1 

in 100 year return period events discussed in Section 4.5.1.3. Because of the very small 

drainage areas involved, the one hour AES distribution was used. Table 4.5.12 

indicates the resulting peak flows for the local drainage systems within the Thompson 

Creek watershed. Table 4.5.13 shows the resulting peak flows for the local drainage 

systems which drain directly to the Otonabee River. As part of its output, the 




Cross 

Section # 

OTTSWMM model provides information on the flows in both the minor system (sewer 

pipes) and the major system (on the streets and other overland flow components. This 

information was used to identify the depth of flow on the streets and in other overland 

flow swales and spill areas. The extent of local flooding was mapped using that data as 

described in Section 4.6.2. 

Table 4.5.11 

Water Levels for Thompson Creek for Releases from Thompson Bay Dam 

3 Logs Removed @ Thompson Bay Dam 7 Logs Removed @ Thompson Bay Dam 

Flow 

(m 3 /s) 

Channel 

Bottom 

Elev. (m) 

Water 

Surface 

Elev. (m) 

Water 

Depth 

(m) 

Flow 

(m 3 /s) 

Channel 

Bottom 

Elev. (m) 

Water 

Surface 

Elev. (m) 

Water 

Depth 

(m) 

1623.3 15.70 209.93 210.59 0.66 43.60 209.93 210.83 0.90 

1601.3 15.70 209.85 210.39 0.54 43.60 209.85 210.66 0.81 

1557.3 15.70 209.36 209.96 0.60 43.60 209.36 210.30 0.94 

1433.3 15.70 208.50 209.14 0.64 43.60 208.50 209.32 0.82 

1309.3 15.72 208.50 208.87 0.37 43.62 208.50 209.12 0.62 

1185.3 15.74 208.50 208.69 0.19 43.64 208.50 208.94 0.44 

1061.3 15.76 207.21 207.99 0.78 43.66 207.21 208.38 1.17 

927.3 15.89 206.54 207.46 0.92 43.79 206.54 207.89 1.35 

791.3 15.89 205.97 207.29 1.32 43.79 205.97 207.67 1.70 

588.3 15.86 205.23 207.28 2.05 43.78 205.23 207.60 2.37 

579.3 15.86 205.08 207.28 2.20 43.78 205.08 207.60 2.52 

577.3 15.86 205.08 207.26 2.18 43.78 205.08 207.58 2.50 

Bridge Culvert 

Culvert 

S-3015 

526.0 15.86 204.93 207.13 2.20 43.78 204.93 207.40 2.47 

518.0 15.86 204.91 206.73 1.82 43.78 204.91 207.06 2.15 

412.0 15.86 204.87 206.71 1.84 43.78 204.87 207.01 2.14 

355.0 15.86 204.47 206.70 2.23 43.78 204.47 206.97 2.50 

283.0 15.86 204.41 206.68 2.27 43.78 204.41 206.89 2.48 

273.0 15.86 204.30 206.68 2.38 43.78 204.30 206.89 2.59 

270.0 15.86 204.30 206.62 2.32 43.78 204.30 206.74 2.44 


Culvert 

S-3010 

260.0 15.86 204.30 206.15 1.85 43.78 204.30 206.65 2.35 

248.0 15.86 204.28 206.40 2.12 43.78 204.28 206.41 2.13 

239.0 15.86 204.28 206.40 2.12 43.78 204.28 206.41 2.13 

199.0 15.86 204.27 206.40 2.13 43.78 204.27 206.40 2.13 

196.0 15.86 204.27 206.40 2.13 43.78 204.27 206.33 2.06 


Culvert 

S-3005 

186.0 15.86 204.15 206.06 1.91 43.78 204.15 206.23 2.08 

170.0 15.86 204.13 205.34 1.21 43.78 204.13 205.68 1.55 

113.0 15.86 203.95 205.29 1.34 43.78 203.95 205.48 1.53 

20.0 15.86 203.82 205.29 1.47 43.78 203.82 205.48 1.66 

17.0 15.86 203.81 205.24 1.43 43.78 203.81 205.38 1.57 

Bridge 

S-3000 

Culvert 

Culvert 

9.0 15.86 203.66 205.21 1.55 43.78 203.66 205.33 1.67 

0.0 15.90 203.48 204.33 0.85 43.80 203.48 204.77 1.29 




Table 4.5.12 

Return Period Flows for Local Drainage Systems in Thompson Creek Watershed 

Street 

Segment 

# 

Fig. 

4.3.1 

2-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

5-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

10-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

25-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

50-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

100-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

2001 0.05 0.06 0.08 0.10 0.13 0.15 

2002 0.04 0.07 0.08 0.11 0.14 0.17 

2003 0.04 0.07 0.09 0.13 0.16 0.20 

2004 0.07 0.12 0.15 0.21 0.28 0.34 

2005 0.04 0.08 0.11 0.17 0.24 0.30 

2101 0.06 0.09 0.11 0.14 0.16 0.18 

2102 0.07 0.10 0.13 0.17 0.21 0.25 

2103 0.08 0.11 0.14 0.17 0.20 0.22 

2104 0.09 0.14 0.20 0.27 0.35 0.40 

2201 0.04 0.06 0.07 0.09 0.11 0.12 

2202 0.06 0.08 0.10 0.13 0.16 0.18 

2203 0.04 0.06 0.07 0.09 0.11 0.12 

2204 0.02 0.03 0.04 0.06 0.08 0.09 

2205 0.02 0.03 0.05 0.06 0.08 0.10 

2206 0.08 0.11 0.14 0.16 0.19 0.21 

2207 0.06 0.09 0.12 0.16 0.19 0.22 

2208 0.05 0.07 0.11 0.15 0.20 0.23 

2210 0.00 0.00 0.00 0.00 0.01 0.01 

2211 0.00 0.00 0.01 0.01 0.01 0.01 

2401 0.12 0.17 0.20 0.25 0.30 0.33 

2402 0.08 0.13 0.13 0.17 0.21 0.25 

2403 0.10 0.14 0.17 0.20 0.24 0.27 

2404 0.05 0.08 0.10 0.14 0.18 0.20 

2405 0.09 0.15 0.19 0.27 0.34 0.40 

2406 0.08 0.13 0.19 0.27 0.36 0.43 

2407 0.11 0.16 0.23 0.34 0.44 0.53 

2408 0.09 0.15 0.20 0.31 0.41 0.50 

2409 0.05 0.09 0.13 0.22 0.31 0.39 

2410 0.09 0.16 0.25 0.38 0.52 0.65 

2411 0.08 0.12 0.15 0.18 0.21 0.23 

2412 0.04 0.06 0.09 0.11 0.14 0.15 

2413 0.05 0.08 0.11 0.14 0.17 0.19 

2414 0.08 0.12 0.17 0.22 0.27 0.31 

2415 0.12 0.17 0.23 0.30 0.38 0.44 

2416 0.09 0.13 0.18 0.26 0.34 0.40 




Street 

Segment 

# 

Fig. 

4.3.1 

Table 4.5.13 

Return Period Flows for Local Systems Draining Directly to the Otonabee River 

2-year 

1-hour AES 

Max. 

Flow 

5-year 

1-hour AES 

Max. 

Flow 

10-year 

1-hour AES 

Max. 

Flow 

25-year 

1-hour AES 

Max. 

Flow 

50-year 

1-hour AES 

Max. 

Flow 

100-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

(m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) 

2500 0.05 0.07 0.09 0.12 0.14 0.16 

2501 0.03 0.05 0.07 0.09 0.12 0.13 

2502 0.02 0.04 0.06 0.08 0.11 0.12 

2503 0.02 0.04 0.05 0.08 0.10 0.11 

2504 0.03 0.05 0.06 0.08 0.10 0.12 

2505 0.05 0.07 0.08 0.11 0.14 0.17 

2506 0.02 0.04 0.05 0.07 0.10 0.11 

2507 0.03 0.04 0.05 0.07 0.09 0.11 

2508 0.02 0.03 0.04 0.06 0.08 0.10 

2510 0.02 0.03 0.03 0.04 0.05 0.06 

2514 0.02 0.02 0.03 0.04 0.04 0.05 

2515 0.11 0.16 0.20 0.26 0.31 0.35 

2516 0.07 0.10 0.13 0.15 0.19 0.21 

2520 0.09 0.13 0.17 0.23 0.28 0.32 

2526 0.14 0.20 0.25 0.31 0.36 0.40 

2527 0.03 0.04 0.05 0.06 0.07 0.08 

2528 0.11 0.17 0.22 0.28 0.34 0.39 

2600 0.02 0.04 0.05 0.07 0.09 0.10 

2601 0.08 0.11 0.14 0.18 0.22 0.26 

2602 0.10 0.15 0.19 0.24 0.30 0.35 

2604 0.01 0.02 0.02 0.03 0.03 0.04 

2605 0.14 0.21 0.25 0.34 0.42 0.49 

2606 0.12 0.19 0.23 0.32 0.42 0.49 

2608 0.03 0.05 0.07 0.09 0.11 0.12 

2607 0.33 0.45 0.55 0.67 0.79 0.88 

2609 0.30 0.44 0.54 0.68 0.82 0.93 

2610 0.20 0.35 0.48 0.65 0.84 0.98 

2611 0.18 0.27 0.34 0.42 0.51 0.58 

2612 0.21 0.29 0.35 0.43 0.51 0.57 

2613 0.11 0.19 0.25 0.33 0.42 0.49 

2614 0.06 0.11 0.17 0.23 0.32 0.37 

2615 0.07 0.11 0.18 0.23 0.33 0.36 

2616 0.07 0.12 0.19 0.24 0.35 0.39 

2619 0.04 0.05 0.06 0.08 0.10 0.11 

2618 0.17 0.29 0.42 0.60 0.79 0.93 

2621 0.10 0.19 0.31 0.46 0.65 0.81 

2622 0.00 0.01 0.01 0.01 0.01 0.01 

2623 0.05 0.07 0.09 0.11 0.13 0.14 

2626 0.03 0.04 0.05 0.06 0.07 0.08 

2627 0.05 0.07 0.08 0.10 0.12 0.14 

2628 0.06 0.09 0.12 0.17 0.21 0.24 

2629 0.04 0.07 0.10 0.14 0.18 0.21 

2630 0.02 0.04 0.07 0.10 0.13 0.16 

2631 0.07 0.10 0.13 0.17 0.21 0.27 

2701 0.04 0.05 0.06 0.08 0.09 0.10 

2703 0.05 0.07 0.08 0.10 0.11 0.12 




Street 

Segment 

# 

Fig. 

4.3.1 

2-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

5-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

10-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

25-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

50-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

100-year 

1-hour AES 

Max. 

Flow 

(m 3 /s) 

2707 0.24 0.34 0.41 0.49 0.58 0.65 

2711 0.00 0.00 0.00 0.01 0.01 0.01 

2801 0.15 0.22 0.27 0.38 0.47 0.54 

2802 0.09 0.15 0.20 0.26 0.32 0.37 

2803 0.06 0.08 0.10 0.12 0.15 0.17 

2804 0.09 0.12 0.16 0.20 0.25 0.29 

2805 0.11 0.16 0.21 0.26 0.33 0.39 

2807 0.18 0.27 0.36 0.46 0.56 0.64 

2808 0.17 0.26 0.36 0.47 0.60 0.71 

2809 0.18 0.28 0.39 0.53 0.69 0.82 

2811 0.12 0.21 0.31 0.44 0.60 0.74 

2812 0.07 0.14 0.22 0.33 0.47 0.61 

2813 0.09 0.14 0.20 0.32 0.43 0.60 

2814 0.05 0.07 0.09 0.15 0.24 0.30 

2900 0.05 0.07 0.09 0.12 0.20 0.26 

2901 0.02 0.03 0.05 0.07 0.13 0.17 

2902 0.03 0.04 0.05 0.06 0.07 0.08 

2910 0.05 0.07 0.08 0.11 0.13 0.15 

2911 0.07 0.10 0.13 0.16 0.20 0.23 

2912 0.04 0.06 0.07 0.10 0.12 0.14 

2921 0.07 0.10 0.13 0.17 0.20 0.23 

2922 0.06 0.09 0.12 0.16 0.20 0.24 

2925 0.11 0.15 0.19 0.27 0.34 0.40 

2500 0.07 0.12 0.16 0.26 0.32 0.42 

2501 0.04 0.07 0.12 0.20 0.25 0.36 

2502 0.05 0.07 0.09 0.12 0.14 0.16 

2503 0.03 0.05 0.07 0.09 0.12 0.13 

2504 0.02 0.04 0.06 0.08 0.11 0.12 

2505 0.02 0.04 0.05 0.08 0.10 0.11 

2506 0.03 0.05 0.06 0.08 0.10 0.12 

2507 0.05 0.07 0.08 0.11 0.14 0.17 

2508 0.02 0.04 0.05 0.07 0.10 0.11 

2510 0.03 0.04 0.05 0.07 0.09 0.11 

2514 0.02 0.03 0.04 0.06 0.08 0.10 

2515 0.02 0.03 0.03 0.04 0.05 0.06 

2516 0.02 0.02 0.03 0.04 0.04 0.05 

2520 0.11 0.16 0.20 0.26 0.31 0.35 

2526 0.07 0.10 0.13 0.15 0.19 0.21 

2527 0.09 0.13 0.17 0.23 0.28 0.32 

2528 0.14 0.20 0.25 0.31 0.36 0.40 

2600 0.03 0.04 0.05 0.06 0.07 0.08 

2601 0.11 0.17 0.22 0.28 0.34 0.39 

2602 0.02 0.04 0.05 0.07 0.09 0.10 

2604 0.08 0.11 0.14 0.18 0.22 0.26 

2605 0.10 0.15 0.19 0.24 0.30 0.35 

2606 0.01 0.02 0.02 0.03 0.03 0.04 

2608 0.14 0.21 0.25 0.34 0.42 0.49 

2607 0.12 0.19 0.23 0.32 0.42 0.49 

2609 0.03 0.05 0.07 0.09 0.11 0.12 






study area (discussed in Section 4.4.3) were used to simulate flows for the six volume 

based events required by the Terms of Reference, as discussed in Section 4.5.1.2. 

Because of the very small drainage areas involved, the one hour AES distribution was 

used for all events except the 193 mm event. For the latter, the Timmins Storm 

distribution was applied. Table 4.5.14 indicates the resulting peak flows for the local 

drainage systems within the Thompson Creek watershed. Table 4.5.15 shows the 

resulting peak flows for the local drainage systems which drain directly to the Otonabee 

River. By comparison with Table 5.4.12 and 5.4.13, it is noted that flows for the 80 

mm, 100 mm and 120 mm events significantly exceed those for the 1 in 100 year event. 

It was estimated, in fact, that the return periods of the 1 hour storms with depths of 80 

mm, 100 mm and 120 mm are approximately 1 in 390 year, 1 in 1,100 years and 1 in 

2,500 years. These far exceed the normal range of return periods used for the “level of 

protection” for local drainage systems. Hence in mapping the extent of local flooding 

only the 40 mm and 60 mm events were considered. Again, the major system flow 

information from the OTTSWMM model was used to calculate flow depths and 

identify the extent of any local flooding for those two events. The results are described 

in Section 4.6.2. 

4.5.3.3 Peterborough Storm of July 14 – 15, 2004 


study area (discussed in Section 4.4.3) were used to simulate flows for the storm of July 

14 – 15, 2004. The rainfall hyetograph used was as described in Section 4.5.1.1. Table 

4.5.14 indicates the resulting peak flows for the local drainage systems within the 

Thompson Creek watershed. Table 4.5.15 shows the resulting peak flows for the local 

drainage systems which drain directly to the Otonabee River. Again, the major system 

flow information was used to calculate flow depths and identify the extent of any local 

flooding. The results are described in Section 4.6.2. 




Street 

Segment 

# 

Fig. 

4.3.1 

Table 4.5.14 

Volume Based Flows for Local Drainage Systems in Thompson Creek Watershed 

40 mm 

1-hour 

AES 

Max. 

Flow 

60 mm 

1-hour 

AES 

Max. 

Flow 

80 mm 

1-hour 

AES 

Max. 

Flow 

100 mm 

1-hour 

AES 

Max. 

Flow 

120 mm 

1-hour 

AES 

Max. 

Flow 

193 mm 

Timmins 

Max. 

Flow 

(m 3 /s) 

July 

2004 

Storm 

Max. 

Flow 

(m 3 /s) 

(m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) 

2001 0.08 0.16 0.25 0.34 0.42 0.02 0.06 

2002 0.09 0.19 0.31 0.44 0.58 0.02 0.07 

2003 0.10 0.22 0.38 0.56 0.76 0.02 0.07 

2004 0.16 0.39 0.69 1.04 1.43 0.03 0.11 

2005 0.12 0.35 0.68 1.06 1.48 0.01 0.08 

2101 0.11 0.20 0.29 0.39 0.50 0.03 0.08 

2102 0.13 0.28 0.46 0.65 0.86 0.03 0.11 

2103 0.14 0.24 0.36 0.47 0.60 0.03 0.10 

2104 0.21 0.46 0.76 1.11 1.49 0.03 0.14 

2201 0.08 0.14 0.20 0.27 0.34 0.02 0.05 

2202 0.11 0.20 0.32 0.43 0.56 0.02 0.07 

2203 0.07 0.14 0.21 0.28 0.36 0.02 0.05 

2204 0.05 0.10 0.17 0.24 0.32 0.01 0.03 

2205 0.05 0.11 0.18 0.26 0.34 0.01 0.03 

2206 0.14 0.23 0.33 0.43 0.54 0.03 0.10 

2207 0.13 0.25 0.38 0.54 0.68 0.03 0.11 

2208 0.12 0.26 0.44 0.66 0.87 0.02 0.09 

2210 0.00 0.01 0.01 0.01 0.02 0.00 0.00 

2211 0.01 0.01 0.02 0.02 0.03 0.00 0.01 

2401 0.21 0.37 0.54 0.72 0.91 0.05 0.15 

2402 0.14 0.27 0.43 0.63 0.82 0.04 0.14 

2403 0.17 0.30 0.44 0.59 0.75 0.04 0.12 

2404 0.11 0.23 0.36 0.50 0.65 0.03 0.11 

2405 0.20 0.45 0.75 1.12 1.57 0.03 0.18 

2406 0.20 0.49 0.86 1.30 1.82 0.03 0.15 

2407 0.25 0.60 1.07 1.63 2.29 0.05 0.17 

2408 0.22 0.57 1.10 1.74 2.48 0.03 0.13 

2409 0.15 0.46 0.98 1.66 2.43 0.02 0.08 

2410 0.26 0.77 1.63 2.75 3.97 0.03 0.15 

2411 0.15 0.25 0.36 0.48 0.60 0.03 0.11 

2412 0.09 0.17 0.27 0.38 0.48 0.02 0.09 

2413 0.11 0.22 0.34 0.48 0.62 0.03 0.11 

2414 0.17 0.35 0.56 0.80 1.05 0.04 0.14 

2415 0.24 0.49 0.81 1.18 1.56 0.04 0.17 

2416 0.19 0.46 0.83 1.23 1.65 0.02 0.12 




Seg. # 

Fig. 

4.3.1 

Table 4.5.15 

Flows for Volume Based Events & July 2004 Storm for 

Local Systems Draining Directly to the Otonabee River 

40 mm 60 mm 80 mm 100 mm 120 mm 193 mm July 2004 

Max. Max. Max. Max. Max. Max. Max. 

Flow Flow Flow Flow Flow Flow Flow 

(m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) 

2500 0.09 0.18 0.27 0.38 0.47 0.06 0.06 

2501 0.07 0.15 0.26 0.37 0.49 0.04 0.04 

2502 0.06 0.14 0.27 0.40 0.54 0.03 0.03 

2503 0.05 0.13 0.27 0.41 0.58 0.03 0.03 

2504 0.06 0.14 0.29 0.46 0.66 0.03 0.03 

2505 0.08 0.19 0.37 0.58 0.83 0.04 0.05 

2506 0.05 0.12 0.23 0.36 0.60 0.04 0.04 

2507 0.05 0.12 0.21 0.34 0.60 0.04 0.04 

2508 0.05 0.11 0.19 0.30 0.59 0.03 0.03 

2510 0.04 0.06 0.10 0.13 0.17 0.04 0.05 

2514 0.03 0.05 0.08 0.10 0.13 0.02 0.03 

2515 0.21 0.38 0.58 0.80 1.02 0.15 0.17 

2516 0.13 0.23 0.35 0.48 0.61 0.09 0.11 

2520 0.18 0.36 0.58 0.82 1.08 0.11 0.13 

2526 0.26 0.43 0.62 0.81 1.02 0.15 0.19 

2527 0.05 0.09 0.13 0.17 0.22 0.03 0.03 

2528 0.23 0.43 0.66 0.90 1.15 0.12 0.14 

2600 0.06 0.11 0.17 0.24 0.32 0.16 0.19 

2601 0.14 0.28 0.45 0.63 0.81 0.18 0.24 

2602 0.19 0.39 0.63 0.89 1.16 0.21 0.26 

2604 0.02 0.04 0.07 0.09 0.12 0.02 0.02 

2605 0.27 0.55 0.89 1.26 1.64 0.24 0.29 

2606 0.25 0.56 0.97 1.39 1.83 0.19 0.24 

2608 0.07 0.13 0.20 0.27 0.36 0.10 0.12 

2607 0.57 0.96 1.43 1.92 2.42 0.32 0.33 

2609 0.56 1.02 1.56 2.05 2.60 0.34 0.38 

2610 0.50 1.12 2.01 3.09 3.89 0.27 0.31 

2611 0.35 0.63 0.98 1.34 1.71 0.19 0.19 

2612 0.36 0.62 0.94 1.26 1.58 0.21 0.21 

2613 0.26 0.55 0.91 1.28 1.66 0.12 0.13 

2614 0.18 0.45 0.81 1.17 1.54 0.07 0.08 

2615 0.19 0.46 0.87 1.30 1.74 0.08 0.09 

2616 0.20 0.49 0.93 1.40 1.87 0.09 0.10 

2619 0.06 0.12 0.19 0.24 0.30 0.04 0.04 

2618 0.46 1.08 1.94 3.02 3.98 0.26 0.30 

2621 0.34 0.94 1.76 2.88 3.81 0.18 0.23 

2622 0.01 0.02 0.02 0.03 0.04 0.01 0.01 

2623 0.09 0.15 0.22 0.30 0.38 0.05 0.06 

2626 0.05 0.08 0.12 0.16 0.20 0.03 0.03 

2627 0.08 0.15 0.23 0.31 0.39 0.05 0.05 

2628 0.13 0.27 0.42 0.58 0.76 0.07 0.07 

2629 0.10 0.24 0.40 0.58 0.78 0.05 0.05 

2630 0.07 0.19 0.33 0.53 0.75 0.03 0.04 

2631 0.14 0.28 0.50 0.76 1.06 0.08 0.08 

2701 0.07 0.11 0.17 0.22 0.28 0.04 0.04 

2703 0.08 0.13 0.19 0.24 0.28 0.03 0.04 

2707 0.42 0.71 1.03 1.37 1.73 0.24 0.25 




Seg. # 

Fig. 

4.3.1 

40 mm 60 mm 80 mm 100 mm 120 mm 193 mm July 2004 

Max. Max. Max. Max. Max. Max. Max. 

Flow Flow Flow Flow Flow Flow Flow 

(m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) (m 3 /s) 

2711 0.00 0.01 0.01 0.02 0.02 0.00 0.14 

2801 0.29 0.64 1.09 1.62 2.38 0.22 0.08 

2802 0.21 0.41 0.66 0.93 1.21 0.11 0.13 

2803 0.10 0.19 0.30 0.41 0.52 0.08 0.17 

2804 0.16 0.32 0.53 0.74 0.97 0.12 0.25 

2805 0.21 0.44 0.74 1.08 1.43 0.15 0.28 

2807 0.37 0.72 1.19 1.70 2.23 0.21 0.30 

2808 0.37 0.80 1.37 2.00 2.65 0.22 0.23 

2809 0.41 0.93 1.62 2.38 3.16 0.24 0.19 

2811 0.33 0.86 1.60 2.41 3.25 0.17 0.20 

2812 0.24 0.72 1.39 2.28 3.10 0.13 0.13 

2813 0.22 0.69 1.45 2.34 3.23 0.15 0.11 

2814 0.10 0.34 0.90 1.62 2.42 0.11 0.06 

2900 0.09 0.30 0.86 1.58 2.40 0.09 0.03 

2901 0.05 0.21 0.75 1.47 2.30 0.05 0.06 

2902 0.05 0.09 0.14 0.19 0.24 0.03 0.08 

2910 0.08 0.17 0.26 0.36 0.46 0.05 0.06 

2911 0.13 0.25 0.38 0.53 0.69 0.08 0.09 

2912 0.07 0.16 0.23 0.32 0.41 0.06 0.08 

2921 0.13 0.26 0.40 0.54 0.70 0.08 0.20 

2922 0.12 0.27 0.44 0.62 0.84 0.07 0.17 

2925 0.20 0.45 0.74 1.02 1.29 0.19 0.12 

4.6 MAPPING OF FLOOD VULNERABLE LOCATIONS 

The previously discussed hydrologic and hydraulic modelling provided the basis for 

mapping the extent of flooding and identification of flood vulnerable 

locations/properties in the Thompson Creek study area. The following sections discuss 

the extent of water course related flooding and local drainage system flooding for the 

various types of storms simulated. 

4.6.1 Results for Thompson Creek Watercourse 

The following sections describe the extent of flood vulnerability directly related to 

flows in the Thompson Creek watercourse. 


Drawing FV-1 shows the flood line along Thompson Creek for the 1 in 100 year storm 

flows presented in Table 4.5.3 and corresponding water levels indicated in Table 4.5.4. 

As indicated, with water depths of a maximum of less than 1 metre, there are no areas 

which are flood vulnerable (other than the immediate overbanks of the creek) for the 1 

in 100 year storm. Consequently, there are no structures which are vulnerable to 

flooding from Thompson Creek itself under that condition. Since the water levels for 




the 1 in 2 year to 1 in 50 year storms are less than those for the 1 in 100 year storm, the 

same conclusion applies for those events. 

4.6.1.2 Volume Based Events for Flood Vulnerability Mapping 

For comparative purposes, Drawing FV-1 shows the flood lines along Thompson Creek 

for the 193 mm storm (Timmins Storm) flows presented in Table 4.5.6 and 

corresponding water levels indicated in Table 4.5.7. A separate map was prepared 

which shows the extent of flood vulnerability for the 20 mm, 40 mm, 60 mm, 80 mm, 

100 mm, 120 mm and 193 mm storms together for future reference purposes. This is 

included as Drawing No. FV-2 in the back pocket of this document. 

As indicated on Drawing FV-1, there are no buildings in the flood plain for the 193 

mm (regulatory) storm. Water depths are predicted to reach a maximum of about 1.5 m 

during this storm event. However, Armour Road would be overtopped for this event. 

This would occur at the low point in the road which is located slightly south of the 

location of the culvert under the road. 

The extent of the flood plain for both the 100 mm and 120 mm 1 hour events is greater 

than that for the 193 mm event. As indicated by Tables 4.5.5, 4.5.6 and 4.5.7, the flows 

and water depths for these two cases are greater than for the 193 mm event. This 

results from the use of the 1 hour AES rainfall distribution for 100 mm and 120 mm 

events versus the “Timmins Storm” 12 hour distribution for the 193 mm storm. The 

intensity of rainfall in the first two cases is greater than in the latter case. Since 

Thompson Creek is a relatively small watershed, it responds more to short duration 

high intensity rainfalls than to higher volume, low intensity, long duration rainfalls. As 

indicated by Drawing FV-2, there are no flood vulnerable buildings for the 100 mm or 

120 mm events although Armour Road would be overtopped in the same manner as for 

the 193 mm event. For the 20 mm, 40 mm, 60 mm and 80 mm events, the extent of the 

flood plain would be less than that shown for the 193 mm event and hence no structures 

would be flood vulnerable. 


Drawing FV-1 also shows the flood line along Thompson Creek for the storm of July 

14 – 15, 2004 based upon the flows presented in Table 4.5.8 and corresponding water 

levels indicated in Table 4.5.9. As indicated, the flooded area is almost identical to that 

which would be inundated during the Regional (Timmins) Storm event. This is 

consistent with the fact that the flows shown in Table 4.5.8 are very similar to those for 

the Timmins Storm. No properties lie within the flooded area but the modelling 

indicates that Armour Road would have been marginally overtopped. These 

observations are believed to be consistent with the anecdotal reports on the extent of 




flooding in Thompson Creek during the July 2004 storm (e.g. as reported in ORCA’s 

Thompson Creek Management Plan (December, 2004)). 

4.6.1.4 Thompson Creek Dam Flows 

Drawing FV-3 shows the flood lines along Thompson Creek for the two scenarios 

modelled regarding the release of flow from the Thompson Creek dam. These are 

based upon the flows presented in Table 4.5.10 and corresponding water levels 

indicated in Table 4.5.11. As indicated, the extent of the flood plain for these two cases 

is greater than any of the previously discussed scenarios. Both of the building that are 

adjacent to the north side of the creek in the Riverpark Village condominium complex 

would be flood vulnerable in both cases. Similarly, about four to six buildings would 

be inundated in the vicinity of the intersection of Francis Stewart Road and Ashdale 

Crescent West. One residence on the south side of the creek just west of Armour Road 

would be impacted. In the case where seven logs were removed from the dam, three 

properties on Eldon Court could be affected. Finally, some areas of the future phase of 

the Waverley Heights development may be flood susceptible under the latter condition. 

The extent would depend upon the final grading of the area of the subdivision adjacent 

to the creek. 

It is emphasized that these scenarios are for illustrative purposes only but they indicate 

that further studies should be carried out by the Trent Severn Waterway to document 

more precisely the level of flood risk and establish policies regarding any future 

operation and maintenance of the Thompson Creek Dam. 

4.6.2 Results for Local Drainage Systems 

The following sections describe the extent of flood vulnerability related to flows in the 

local drainage systems within the Thompson Creek study area. As in the earlier 

discussion, the areas within the Thompson Creek watershed and those draining directly 

to the Otonabee River are addressed separately. To identify potential problem areas, 

the water depths in the major system computed by OTTSWMM were compared to the 

height of the curb (assumed to be an average of 150 mm) on each road segment. Where 

the depth indicated was more that 150 mm, the extent of ponding and potential flooding 

was estimated using the available contour mapping. In cases where significant ponding 

was indicated, a field inspection was completed to verify the results since the 

topographic mapping has a 0.5 meter contour interval which may not be sufficiently 

accurate in all cases. Maps of the potential extent of flooding were created for the 

identified problem areas. 





Areas within Thompson Creek Watershed 

As indicated in Section 4.3.1, there are three separate storm sewer systems within the 

Thompson Creek watershed: the Waverley Heights system with two outfalls, the 

Armour Road system with several outfalls and the Ashdale Crescent system. 

Waverley Heights – there are two locations within the existing Waverley Heights 

subdivision where the modelling indicated that water would pond on the street to 

unacceptable levels under some circumstances: 

1. Corner of Scollard Drive (near intersection with Francis Stewart Road) 

Extensive ponding of water at this location was reported by the residents of 

Scollard Drive at the Public Information Centres for both this study and the 

Master Flood Study which proceeded it. Table 4.6.1 indicates the depth of 

water for the 1 in 2 year to 1 in 100 year storms. Based upon this information, 

the depth would exceed the curb level for a 1 in 10 year storm. However, as 

indicated in Photograph 4.6.1, the majority of the affected area (the west side of 

the street) is actually driveway rather than curbs. Hence the water ponds up the 

driveways for much more frequent events. In addition, the modelling does not 

account for blockage of the catchbasins in this area which would increase the 

frequency of ponding. Drawing SF-1 shows the estimated extent of flooding 

for the 1 in 100 year storm. As indicated, the lots affected slope toward the 

street at the front but away from the road beyond the houses. Hence once the 

water reaches a depth of about 0.5 m to 0.75 m, it would spill around the houses 

and generally flow towards the golf driving range located west of these 

properties. 




Street 

Segment 

# 

Fig. 

4.3.1 

Table 4.6.1 

Depth of Water for Scollard Dr. and Eldon Crt. for 1 in 2 to 1 in 100 Year Storm 

2-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

Eldon Court & Francis Stewart Road 

5-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

10-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

25-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

50-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

100-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

2101 0.06 39 0.09 44 0.11 49 0.14 54 0.16 60 0.18 62 

2102 0.07 35 0.10 40 0.13 44 0.17 51 0.21 58 0.25 62 

2103 0.08 42 0.11 49 0.14 55 0.17 61 0.20 64 0.22 66 

2104 0.09 114 0.14 135 0.20 154 0.27 173 0.35 189 0.40 200 

Scollard Drive 

2408 0.09 32 0.15 37 0.20 41 0.31 50 0.41 59 0.50 63 

2409 0.05 28 0.09 34 0.13 38 0.22 46 0.31 55 0.39 62 

2410 0.09 115 0.16 141 0.25 166 0.38 195 0.52 220 0.65 238 

Francis Stewart Road near Scollard Drive Intersection 

2415 0.12 50 0.17 61 0.23 67 0.30 74 0.38 81 0.44 86 

2416 0.09 43 0.13 54 0.18 63 0.26 70 0.34 77 0.40 83 

Photograph 4.6.1: 

Flood Susceptible Area- Scollard Drive 




The problem occurs at this location for several reasons: 

 

 

 

 

there is an extensive drainage area upstream of this location 

(approximately 6.5 hectares) 

the road east of this location slopes steeply down to this point causing 

flow on the street to travel rapidly down to this point and probably 

reducing the efficiency of the upstream catchbasins in capturing flow 

the road north of this location slopes back from the intersection of 

Scollard Drive and Francis Stewart Road forming a low point at the 

west side of the corner. Although there are two catchbasins on either 

side of the street, they do not have sufficient capacity to accept all the 

flow and, based on field observations, are probably subject to blockage 

by debris during storm events 

there is no defined overland flow route to the west of this point to safely 

convey the accumulated flow past the affected houses. 

Based on the extent of flooding and the number of properties affected, a 

solution to this problem was identified as discussed in Section 5.1. 

2. Northwest Corner of Intersection of Eldon Court and Francis Stewart Road 

Local residents reported that relatively frequent ponding of water occurs at the 

corner of Eldon Court and Francis Stewart Road (See Photograph 4.6.2 for 

location). The OTTSWMM modelling confirms that this is the case. 

Drawing SF-1 shows the extent for the 1 in 100 year storm. It was estimated 

that ponding would be initiated for storms between a 1 in 2 year and 1 in 5 year 

magnitude (see Table 4.6.1). However, this does not allow for blockage of the 

catchbasins in the area which probably occurs relatively often based on field 

observations. 

The problem occurs at this location because Eldon Court slopes towards the 

intersection with Francis Stewart Road although the latter street is higher than 

the intersection on both the east and west sides of the intersection. Hence there 

is a low point at this location. The storm sewer on Eldon Court drains in the 

opposite direction to the slope of the street hence all the flow from the street 

must enter the sewer at the noted low point. During heavy storms, the 

catchbasins at this location do not have sufficient capacity and are probably 

subject to relatively frequent blockage by debris. 




Photograph 4.6.2: 

Flood Susceptible Area – Eldon Court 

As indicated on Drawing SF-1, for infrequent events the ponded flow would 

overtop the curb and flow west from the affected location and spill onto the 

adjacent private property. In this area, the land slopes quite steeply towards 

Thompson Creek and it is estimated that the spill would run down the slope into 

the creek without impacting the residence. Although no direct flood damages 

would be caused, potential means of alleviating this “nuisance” flooding are 

discussed in Section 5.2. 

Armour Road – the OTTSWMM modelling indicated depths of flow less than the curb 

height along Armour Road north of Thompson Creek. Hence no areas of potential 

flooding were identified 

Ashdale Crescent/Francis Stewart Rd. West of Armour Rd. – no areas of potential 

flooding were indicated by the OTTSWMM model for the 2 to 100 year events. 

Areas Draining Directly to the Otonabee River 

There are six local storm sewer systems which drain directly to the Otonabee River 

within the study area (as described in Section 4.3). The following discusses areas of 

potential flooding within each of these areas. 

1. Armour Road, Paddock Wood and Whitaker Street system This system drains 

these streets to an outfall to the Otonabee River just below the Hydro Dam. No 




Street 

Segment 

# 

Fig. 

4.3.1 

areas of potential flooding were indicated within this system by the 

OTTSWMM model for the 1 in 2 year to 1 in 100 year storms. 

2. Franmor Drive, Chapel Drive, Dainton Drive, Abbey Lane and part of Armour 

Road system – this area drains to the same outfall as the previously described 

area joining it about 180 m from the river. Table 4.6.2 shows the estimated 

depth of flow in the major system for the 1 in 2 year to 1 in 100 year storms. 

Drawing SF-2 shows the extent of potential local flooding in this area for the 1 

in 100 year storm. As indicated, the depths are such that although the curbs 

would overtop and driveways would be partially flooded, no structures would 

be impacted. Hence this may be considered to be “nuisance flooding” which 

does not require any specific remedial measures to reduce it. Potential options 

to address it are, however, discussed in Section 5.3. 

Table 4.6.2 

Depth of Water for 1 in 2 Year to 1 in 100 Year Storm in Franmor Drive Area 

2-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

5-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

10-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

25-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

50-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

100-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

2600 0.02 68 0.04 83 0.05 94 0.07 103 0.09 111 0.10 118 

2601 0.08 42 0.11 49 0.14 55 0.18 62 0.22 66 0.26 69 

2602 0.10 47 0.15 57 0.19 63 0.24 68 0.30 74 0.35 78 

2604 0.01 54 0.02 62 0.02 66 0.03 72 0.03 78 0.04 83 

2605 0.14 56 0.21 65 0.25 69 0.34 77 0.42 85 0.49 91 

2606 0.12 127 0.19 150 0.23 163 0.32 185 0.42 202 0.49 215 

2608 0.03 76 0.05 93 0.07 102 0.09 112 0.11 122 0.12 127 

2607 0.33 67 0.45 76 0.55 82 0.67 90 0.79 95 0.88 99 

2609 0.30 65 0.44 75 0.54 81 0.68 91 0.82 96 0.93 100 

2610 0.20 155 0.35 190 0.48 213 0.65 238 0.84 262 0.98 277 

2611 0.18 62 0.27 71 0.34 77 0.42 85 0.51 92 0.58 96 

2612 0.21 57 0.29 65 0.35 69 0.43 74 0.51 79 0.57 83 

2613 0.11 124 0.19 152 0.25 167 0.33 187 0.42 202 0.49 215 

2614 0.06 95 0.11 125 0.17 145 0.23 163 0.32 185 0.37 194 

2615 0.07 39 0.11 50 0.18 62 0.23 67 0.33 77 0.36 79 

2616 0.07 104 0.12 128 0.19 152 0.24 166 0.35 190 0.39 197 

2619 0.04 33 0.05 36 0.06 38 0.08 42 0.10 45 0.11 48 

2618 0.17 145 0.29 178 0.42 203 0.60 230 0.79 255 0.93 273 

2621 0.10 119 0.19 153 0.31 181 0.46 211 0.65 239 0.81 258 

2622 0.00 35 0.01 40 0.01 44 0.01 48 0.01 52 0.01 56 

2623 0.05 36 0.07 41 0.09 44 0.11 48 0.13 52 0.14 56 

2626 0.03 71 0.04 81 0.05 90 0.06 97 0.07 102 0.08 106 

2627 0.05 90 0.07 101 0.08 108 0.10 120 0.12 128 0.14 134 

2628 0.06 38 0.09 45 0.12 52 0.17 61 0.21 65 0.24 68 

2629 0.04 86 0.07 103 0.10 117 0.14 133 0.18 147 0.21 157 

2630 0.02 69 0.04 88 0.07 102 0.10 118 0.13 132 0.16 142 

2631 0.07 103 0.10 119 0.13 131 0.17 145 0.21 158 0.27 171 

2701 0.04 33 0.05 36 0.06 39 0.08 42 0.09 45 0.10 47 




The one location where flooding may be of concern is at the low point on 

Armour Road just south of Whitaker Street. City staff reported that this 

location overtopped during the July 2004 storm. The OTTSWMM modelling 

indicates potential flooding from the road drainage system or by 

surcharging/insufficient inlet capacity of the main sewer system. The drainage 

system at this location is quite complex with several large areas converging on 

the east side of Armour Road in a low area. There is an inlet to the system to 

pick up overland drainage from the adjacent condominium development and a 

partially blocked culvert under Armour Road. Potential means of improving 

this system are discussed in Section 5.3. 

3. Armour Road south of Moir Street and Moir Street system – this system drains 

to an outfall at the end of Moir Street. Table 4.6.3 shows potential depths of 

flow in the major system for this area for the 1 in 2 year to 1 in 100 year storm. 

Drawing SF-2 identifies the extent of potential flooding for the 1 in 100 year 

event. As indicated, the OTTSWMM modelling suggests a potential for flow 

depths along Armour Road to overtop the curb for relatively frequent events 

(e.g. 1 in 2 year). However, depths are such that although the area west of the 

road is relatively flat, buildings would probably not be impacted until events 

greater than the 1 in 100 year event. Since the land generally slopes away from 

the road towards the Otonabee River, any flow which overtops the high point 

adjacent to the buildings would spill down towards Lisburn Street and travel 

overland to the river. This could potentially cause flooding of the buildings 

which front on Lisburn Street. A similar spill is also indicated at the corner of 

Moir Street and Lisburn Street but this would drain overland to the river 

without impacting any structures. 

4. Spencleys Lane, Vinette Street system – this system also drains the south part of 

Lisburn Street and a small area of Armour Road to an outfall to the Otonabee 

River at the end of Vinette Street. No potential flooding is indicated by the 

OTTSWMM model within this system for the 1 in 2 year to 1 in 100 year 

storm. 

5. Dunlop Street system – this system also drains a small area of Armour Road to 

an outfall to the Otonabee River at the end of Dunlop Street. No potential 

flooding is indicated by the OTTSWMM model within this system for the 1 in 2 

year to 1 in 100 year storm. 




Street 

Segment 

# 

Fig. 

4.3.1 

Table 4.6.3 

Depth of Water for 1 in 2 Year to 1 in 100 Year Storm in Moir Street Area 

2-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

5-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

10-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

25-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

50-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

100-Year 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

2801 0.06 34 0.08 37 0.10 40 0.12 44 0.15 48 0.17 51 

2802 0.09 38 0.12 44 0.16 49 0.20 56 0.25 62 0.29 65 

2803 0.11 41 0.16 49 0.21 57 0.26 63 0.33 67 0.39 71 

2804 0.18 63 0.27 71 0.36 79 0.46 88 0.56 95 0.64 100 

2805 0.17 61 0.26 70 0.36 79 0.47 90 0.60 97 0.71 103 

2807 0.18 62 0.28 72 0.39 82 0.53 94 0.69 102 0.82 109 

2808 0.12 126 0.21 157 0.31 182 0.44 207 0.60 231 0.74 249 

2809 0.07 104 0.14 135 0.22 161 0.33 187 0.47 212 0.61 232 

2811 0.09 113 0.14 134 0.20 156 0.32 185 0.43 205 0.60 231 

2812 0.05 36 0.07 40 0.09 45 0.15 57 0.24 68 0.30 74 

2813 0.05 27 0.07 32 0.09 34 0.12 38 0.20 47 0.26 53 

2814 0.02 12 0.03 20 0.05 29 0.07 33 0.13 38 0.17 43 

6. Parkhill Road East system – this system also drains a small area of Armour 

Road to an outfall to the Otonabee River near the Parkhill Road bridge. No 

potential flooding is indicated by the OTTSWMM model within this system for 

the 1 in 2 year to 1 in 100 year storm. 



The following section discusses the results for the simulations of the 40 mm and 60 mm 

volume based events for the three separate storm sewer systems within the Thompson 

Creek watershed. The results are generally very similar to those for the 1 in 2 year to 1 

in 100 year storm. 

Waverley Heights – flooding is indicated for the same two locations within the existing 

Waverley Heights subdivision described in Section 4.6.2.2. Table 4.6.4 shows the 

predicted depths of water for the 40 mm and 60 mm events for the two locations. 




1. Drawing SF-3 shows the estimated extent of flooding for the 40 mm and 60 mm 

events for Scollard Drive. The 193 mm event produces lower flows and water 

levels since it is distributed over 12 hours. As indicated, three lots are affected 

on the west side of the bend in Scollard Drive. The reasons for flooding are as 

previously discussed in Section 4.6.2.2. As noted earlier, potential solutions to 

this problem are discussed in Section 5.1. 

2. Drawing SF-3 shows the extent of potential ponding at the corner of Eldon 

Court and Francis Stewart Road for the 40 mm and 60 mm storms. As 

previously discussed, for infrequent events the ponded flow would overtop the 

curb and flow west from the affected location and spill onto the adjacent private 

property. Although no direct flood damages would be caused, potential means 

of alleviating this “nuisance” flooding are discussed in Section 5.2. 

Table 4.6.4 

Depth of Water for Volume Based Events for Scollard Drive and Eldon Court 

Street 

Segment 

# 

Fig. 

4.3.1 

40 mm 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 


60 mm 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

193 mm 

Timmins 

Max. 

Flow 

(m 3 /s) 

Max 

Depth 

(mm) 

2101 0.11 50 0.20 64 0.03 31 

2102 0.13 45 0.28 64 0.03 23 

2103 0.14 56 0.24 68 0.03 32 

2104 0.21 157 0.46 210 0.03 78 


2408 0.22 43 0.57 66 0.03 14 

2409 0.15 39 0.46 65 0.02 9 

2410 0.26 171 0.77 253 0.03 73 


2415 0.24 68 0.49 91 0.04 34 

2416 0.19 64 0.46 89 0.02 28 

Armour Road – the OTTSWMM modelling indicated no areas of potential flooding 

adjacent to Armour Road north of Thompson Creek for the 40 mm and 60 mm events. 




Ashdale Crescent/Francis Stewart Road west of Armour Road – no areas of potential 

flooding were indicated by the OTTSWMM modelling for the 40 mm and 60 mm 

events. 


The results for the 40 mm and 60 mm volume based events for the six local storm sewer 

systems which drain directly to the Otonabee River within the study area (as described 

in Section 4.3) are similar to those for the 1 in 2 year to 1 in 100 year event. The 

following discusses areas of potential flooding within each of these areas. 

1. Armour Road, Paddock Wood and Whitaker Street system This system drains 

these streets to an outfall to the Otonabee River just below the Hydro Dam. 

One area of potential flooding was indicated within this system by the 

OTTSWMM model for the six volume events. This is a relatively minor spill 

of water from Armour Road onto the property to the east just north of Whitaker 

Street. This would begin for the 60 mm storm. The spill would enter the 

parking lot of the condominium complex and be picked up be the parking lot 

drainage system. Since this occurs for such extreme events (at or beyond the 1 

in 100 year event), it is not considered serious enough to require any remedial 

measures. 

2. Franmor Drive, Chapel Drive, Dainton Drive, Abbey Lane and part of Armour 

Road system – Table 4.6.5 shows the estimated depth of flow in the major 

system for the 40 mm and 60 mm volume based storms. Drawing SF-4 shows 

the extent of potential local flooding in this area for these storms. As indicated, 

the depths are such that based upon the available topographic information, no 

actual structures would be impacted. Several properties would have driveways 

or lawns inundated for the 60 mm event. This would primarily be near the 

intersection of Abbey Lane and Franmor Drive, along the west side of Franmor 

Drive and on Chapel Drive. Although this occurs for only rare events, potential 

options to address it are, however, discussed in Section 5.3. 

The low point on Armour Road just south of Whitaker Street is also shown to 

be flooded as previously discussed. Potential means of improving this system 

are also discussed in Section 5.3. 




Table 4.6.5 

Depth of Water for Volume Based Events for Franmor Drive Area 

Street 

Segment 

# 

Fig. 

4.3.1 

40 mm 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

60 mm 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

193 mm 

Timmins 

Max. 

Flow 

(m 3 /s) 

Max 

Depth 

(mm) 

2600 0.06 96 0.11 123 0.06 96 

2601 0.14 56 0.28 72 0.14 56 

2602 0.19 64 0.39 82 0.19 64 

2604 0.02 67 0.04 87 0.02 67 

2605 0.27 70 0.55 95 0.27 70 

2606 0.25 166 0.56 225 0.25 166 

2608 0.07 104 0.13 131 0.07 104 

2607 0.57 83 0.96 102 0.57 83 

2609 0.56 83 1.02 104 0.56 83 

2610 0.50 217 1.12 292 0.50 217 

2611 0.35 79 0.63 99 0.35 79 

2612 0.36 70 0.62 87 0.36 70 

2613 0.26 170 0.55 224 0.26 170 

2614 0.18 149 0.45 208 0.18 149 

2615 0.19 63 0.46 89 0.19 63 

2616 0.20 155 0.49 215 0.20 155 

2619 0.06 39 0.12 51 0.06 39 

2618 0.46 210 1.08 288 0.46 210 

2621 0.34 188 0.94 274 0.34 188 

2622 0.01 45 0.02 58 0.01 45 

2623 0.09 45 0.15 58 0.09 45 

2626 0.05 92 0.08 110 0.05 92 

2627 0.08 110 0.15 139 0.08 110 

2628 0.13 54 0.27 71 0.13 54 

2629 0.10 121 0.24 164 0.10 121 

2630 0.07 105 0.19 151 0.07 105 

2631 0.14 133 0.28 176 0.14 133 

2701 0.07 39 0.11 49 0.07 39 

3. Armour Road south of Moir Street and Moir Street system – the results for this 

system are as discussed for the 1 in 100 year event. Table 4.6.6 shows potential 

depths of flow in the major system for this area for the 40 mm and 60 mm 

events. Drawing SF-4 identifies the extent of potential flooding for these 

events. Given the extent of the spill, means to reduce the problem are discussed 

in Section 5.4. 




Table 4.6.6 

Depth of Water for Volume Based Events for Moir Street Area 

Street 

Segment 

# 

Fig. 

4.3.1 

40 mm 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

60 mm 

1-hour AES 

Max. Max 

Flow Depth 

(m 3 /s) (mm) 

193 mm 

Timmins 

Max. 

Flow 

(m 3 /s) 

Max 

Depth 

(mm) 

2801 0.10 40 0.19 54 0.08 37 

2802 0.16 50 0.32 67 0.12 43 

2803 0.21 58 0.44 74 0.15 47 

2804 0.37 80 0.72 104 0.21 65 

2805 0.37 81 0.80 108 0.22 66 

2807 0.41 84 0.93 115 0.24 68 

2808 0.33 186 0.86 264 0.17 146 

2809 0.24 165 0.72 247 0.13 132 

2811 0.22 159 0.69 243 0.15 139 

2812 0.10 46 0.34 77 0.11 48 

2813 0.09 35 0.30 58 0.09 35 

2814 0.05 31 0.21 48 0.05 28 

4. Spencleys Lane, Vinette Street system – this system also drains the south part of 

Lisburn Street and a small area of Armour Road to an outfall to the Otonabee 

River at the end of Vinette Street. No potential flooding is indicated by the 

OTTSWMM model within this system for the 40 mm and 60 mm events. 

5. Dunlop Street system – this system also drains a small area of Armour Road to 

an outfall to the Otonabee River at the end of Dunlop Street. No potential 

flooding is indicated by the OTTSWMM model within this system the 40 mm 

and 60 mm events 

6. Parkhill Road East system – this system also drains a small area of Armour 

Road to an outfall to the Otonabee River near the Parkhill Road bridge. No 

potential flooding is indicated by the OTTSWMM model within this system for 

the 40 mm and 60 mm events. 






Table 4.6.7 compares depths of flow computed by OTTSWMM for the major system 

for the storm of July 2004 with those for the 1 in 5 year AES 1 hour storm for the parts 

of the three main systems within the Thompson Creek watershed. As indicated, the 

July 2004 storm resulted in flows/depths very similar to the 1 in 5 year event for these 

very small local drainage systems. The reason is that although the July 2004 storm had 

a high volume of rainfall, it was spread out over a long duration – much greater than the 

time of concentration for these systems. Within the Waverley Heights subdivision, it is 

likely that some ponding was observed at the corner of Scollard Drive and possibly at 

the intersection of Eldon Court and Francis Stewart Road. Drawing SF-1 shows the 

estimated areas of street flooding for the July 2004 event. 

Table 4.6.7 

Water Depth for July 2004 vs 1 in 5 Year Storm for Thompson Creek Systems 

Major System Street 

Segment # (See Fig. 

4.3.1) 

July 2004 Storm 

Max. 

Flow 

(c.m.s.) 

Max. 

Depth 

(mm) 

5-year 1-hr AES 

Max. 

Flow 

(c.m.s.) 

Max. 

Depth 

(mm) 

Armour Road North of Thompson Creek 

2001 0.06 38 0.06 39 

2002 0.06 39 0.06 40 

2003 0.07 41 0.08 42 

2004 0.11 48 0.11 48 

2005 0.08 37 0.09 38 


2101 0.08 42 0.09 44 

2102 0.11 41 0.10 40 

2103 0.10 46 0.11 49 

2104 0.14 133 0.14 135 


2408 0.13 36 0.15 37 

2409 0.08 32 0.09 34 

2410 0.15 138 0.16 141 


2415 0.17 61 0.17 61 

2416 0.12 52 0.13 54 


As for the Thompson Creek systems, depths of flow computed by OTTSWMM for the 

major system for the six main systems which drain directly to the Otonabee River for 

the storm of July 2004 are very similar to those for the 1 in 5 year AES 1 hour storm. 

To the best of our knowledge, this agrees with the fact that little, if any, flooding was 

reported in these areas for the July 2004 storm. Drawing SF-2 shows the estimated 

areas of street flooding for the event. 




4.7 FLOOD DAMAGE ESTIMATION 

One of the factors considered in deciding whether to proceed with flood protection 

measures for flood vulnerable areas is the economics of the project. Generally, a 

benefit-cost analysis is completed to evaluate whether the dollar value flood damages 

prevented by flood protection exceeds the capital and operating costs of the project. 

Many other factors must be considered such as environmental issues and social issues 

but the benefit-cost relationship is generally an important decision factor. 

To estimate the benefit side of the “equation,” a method of assessing the dollar value of 

flood damages must be identified and applied. The result is generally a value known as 

the Present Value (PV) of the average annual flood damages (AAFD). It can be 

directly compared with the sum of the capital cost and present worth of 

operation/maintenance of any protection works. The approach used to estimate the PV 

of the AAFD is generally as follows: 

1. The extent of flooding is identified for different return periods (e.g. 1 in 2 year, 

1 in 5 year, 1 in 10 year, 1 in 25 year, 1 in 50 year and 1 in 100 year). 

2. Any assets affected by the flooding are identified for each return period and an 

estimate of the $ damages which each would suffer under those conditions is 

assessed. Generally more assets will be affected by larger events. Hence the $ 

damages will increase with the return period of the event. 

3. The AAFD is calculated by weighting the estimated damage for each return 

period by its probability of occurrence, e.g. using the six return periods noted 

above, the AAFD would be: 

AAFD = 0.5 * D2 + 0.2 * D5 + 0.1 * D10 + 0.04 * D25 + 0.02 * D50 + 0.01 * D100 

where Dn is the $ damage associated with the return period n 

and the weighting factors 0.5, 0.2, etc. are the inverse of the return 

period, e.g. 1/2, 1/5, 1/10, etc. 

4. The present value is calculated using an accounting formula which converts an 

infinite stream of annual values to a present worth using a discount factor. 

It is worth noting that in calculating the AAFD, less frequent events have relatively 

little impact on the total since their weighting is so small compared to more frequent 

events. For example, any damages occurring for a 100 year storm have one 50 th of the 

weight for damages from a 2 year event. This means that it is not necessary to evaluate 




higher return period events (e.g. 1 in 200 year or 1 in 500 year) since they do not 

materially affect the AAFD. 

In theory, it was intended to apply the procedure described to each flood vulnerable 

area within the Thompson Creek study area to assess the economic benefits of 

providing flood protection for these locations. As described in the following sections, 

in practice, this was only necessary in a few cases as most locations suffered no 

tangible damages or did so only for return periods greater than 1 in 100 years. 

4.7.1 Results for Thompson Creek Watercourse 

Potentially flood vulnerable areas adjacent to the Thompson Creek watercourse for 

events up to the 1 in 100 year storm were discussed in Section 4.6.1.1. As indicated, 

there are no flood prone structures for events up to that return period. Hence based 

upon the procedure described above, the AAFD will effectively be zero. Some flood 

prone structures were identified for the 100 mm and 120 mm volume based events. 

However, given that the 1 hour rainfall for the 1 in 100 year event is 56 mm and for the 

1 in 50 year event is 52 mm, it can be seen that the return periods for the 100 mm and 

120 mm events are considerably higher (of the order of 1,000’s of years). Hence they 

cannot materially affect the AAFD estimate. Additional flood prone structures were 

identified for the scenarios where water was released from the Thompson Creek Dam. 

However, as noted in Section 4.6.1.4, it is not feasible to assign a realistic probability to 

those illustrative scenarios. Hence they cannot be included in the AAFD assessment. 

More detailed studies of that component of the flood risk from the Thompson Creek 

Dam may be able to address that issue in the future. 

From an economic viewpoint, there would be no justification for providing additional 

flood protection to the few flood prone structures adjacent to Thompson Creek since 

they are potentially flooded so rarely that there would essentially be zero economic 

benefit. 

4.7.2 Results for Local Drainage Systems 

Potentially flood vulnerable areas in the local drainage systems in the Thompson Creek 

study area for events up to the 1 in 100 year storm were discussed in Section 4.6.2.1. 

The following areas were identified as flood vulnerable: 

1. Corner of Scollard Drive (near intersection with Francis Stewart Road) 

2. Northwest Corner of Intersection of Eldon Court and Francis Stewart Road 

3. Franmor Drive, Chapel Drive area 

4. Armour Road south of Moir Street 




Flood damage estimates for each of these cases are discussed in the following sections: 

Corner of Scollard Drive (near intersection with Francis Stewart Road) – as discussed 

in Section 4.6.2, water frequently ponds at the corner of Scollard Drive just south of its 

intersection with Francis Stewart Road. The OTTHYMO simulations indicate that the 

depth of water on the street would be approximately 0.25 m for a 1 in 100 year storm. 

For the 120 mm storm the depth was estimated to be about 0.5 m. These are potentially 

underestimated since they do not account for blockage of the catchbasins in the low 

point at the bend nor the momentum of the water as it flows down the steep hill east of 

the corner. However, given that the houses themselves are super-elevated above the 

road by at least 0.5 m to 0.75 m, it does not appear that damage to the buildings 

themselves would occur for events up to the 1 in 100 year storm. Costs have been 

incurred by the residents to clean and maintain their driveways and landscaped areas at 

the front of their properties. In addition, it was reported that during the July 2004 storm 

at least one house experienced basement flooding from the sanitary sewer system. This 

probably occurred due to infiltration of stormwater into manholes of the sanitary sewer 

system when water ponded over them. Overall, therefore, the AAFD due to direct 

damages is zero but due to indirect damages may amount to several thousand dollars 

per year. For estimation purposes, a total value of $5,000 per year has been adopted to 

cover costs to the three properties affected and costs incurred by the City in attending to 

this situation (e.g. pumping water away to the outlet north of Francis Stewart Drive). 

An AAFD of $5,000 per year would have a present value of about $125,000 using a 

discount rate of 4%. This is the amount which could be invested in remedial measures 

to create a benefit-cost ratio of 1.0. If more than this is required it would have to be 

justified by other supporting factors such as social or environmental benefits. 

Northwest Corner of Intersection of Eldon Court and Francis Stewart Road – as 

discussed in Section 4.6.2.1, ponding occurs relatively frequently at this location as it is 

a low point with inadequate catchbasin capacity subject to blockage by debris. 

However, although the curb would overtop for a 1 in 10 year storm, the boulevard 

would not be overtopped until at least a 1 in 100 year event or larger. Hence the spill 

which would occur onto the adjacent private property would occur less frequently than 

1 in 100 years. Since that spill would not appear to directly impact the residence or any 

other structure, it would cause no direct flood damage. Hence the AAFD is estimated 

to be zero. On that basis, there would be no economic justification for reducing the 

extent of ponding/flooding at this location. However, it may be justified to reduce the 

nuisance to local residents and improve their level of service. 

Franmor Drive, Chapel Drive, Abbey Lane area – in this area, about 12 properties 

appear to be potentially flood vulnerable for events up to the 1 in 100 year storm. 




However, as discussed in Section 4.6.2.1, because of the super-elevation of the houses 

above the street, it appears that only driveways and landscaped areas would be affected 

for return periods up to 1 in 100 years. No direct damages to the houses are expected to 

occur. Indirect damages are anticipated to be incurred by the residents and the City in 

cleaning up after flood events. This has been estimated as an average of $500 per 

property per year plus $1,000 per year for City input. Total indirect damages would 

therefore total an average of $7,000 per year. The present value of this amount is 

$175,000. 

Armour Road south of Moir Street - in this area, about 5 properties appear to be 

potentially flood vulnerable for events up to the 1 in 100 year storm. However, as 

discussed in Section 4.6.2.1, because of the superelevation of the buildings above the 

street, it appears that only driveways and landscaped areas would be affected for return 

periods up to 1 in 100 years. No direct damages to the houses and apartment buildings 

are expected to occur. Indirect damages are anticipated to be incurred by the residents 

and the City in cleaning up after flood events. This has been estimated as an average of 

$500 per property per year plus $1,000 per year for City input. Total indirect damages 

would therefore total an average of $3,500 per year. The present value of this amount 

is $87,500 using a discount factor of 4%. 

4.8 SUMMARY OF FLOOD VULNERABILITY 

A detailed analysis has been completed of flood vulnerability in the Thompson Creek 

study area. This was divided into two components: flooding related directly to the 

Thompson Creek watercourse, and flooding from the local drainage systems which 

drain to Thompson Creek and directly to the Otonabee River. The main conclusions of 

these investigations are: 

1. The level of flooding experienced in the Thompson Creek area during the July 

2004 storm was relatively low with only a few occurrences of road overtopping, 

local ponding and basement flooding being reported. 

2. The extent of flood vulnerability related to the Thompson Creek water course is 

low with no properties within either the 1 in 100 year storm flood line or the 

Regulatory flood line (the 193 mm Timmins Storm). Armour Road would be 

overtopped under such conditions but this is acceptable for a road of its 

classification. 

3. Release of water from the Thompson Creek dam presents a potential flood risk 

to a number of properties west of Armour Road. It is recommended that the 

Trent Severn Waterway complete further studies of the risk involved and 




establish a policy restricting releases to a maximum level which avoids 

downstream flood damages. Similarly, it is recommended that a dam safety 

study be completed to assess stability of the dam and the risk under conditions 

of dam failure. 

4. A limited number of areas were identified which are vulnerable to flooding 

from the local drainage system. In general, these involve nuisance flooding 

with direct damages to structures only likely for exceptionally rare events. 

Average annual flood damages were assessed based on indirect damages and 

range from $3,500 to $7,000 per year for these locations. Options to address 

these cases, will be considered in Section 5.0 of this report. 




5.0 PHASE 2 – EVALUATION OF FLOOD PROTECTION 

OPTIONS 

Four areas have been identified within the local drainage systems of the Thompson 

Creek study area where flood protection options should be considered. None were 

identified related to flooding directly from the Thompson Creek watercourse. The 

following sections discuss alternative ways in which flood remediation could be 

addressed including the “base” option of do-nothing. Where appropriate, 

environmental and social factors are discussed before providing a recommended 

“preferred alternative” for consideration by the City and the public. 

5.1 CORNER OF SCOLLARD DRIVE (NEAR FRANCIS STEWART RD) 

Figure 5.1 shows the area of flood vulnerability at the corner of Scollard Drive near 

Francis Stewart Road. As discussed in Section 4.6.2.1, this problem occurs because 

there is a low point at the west side of the corner with insufficient inlet and sewer 

capacity to pick up the flows arriving at this location. In addition, there is no overland 

flow outlet from the low point other than by spilling over the private property west of 

the road. Several potential alternatives can be considered to address this problem: 

1. Intercept flows and transmit them safely to an outlet to Thompson Creek. In 

this case, this would involve constructing a “trench” across the road covered 

with a suitable grating just at the start of the bend in the road. This would be 

connected to a manhole which would connect to a new storm sewer which 

would run parallel to the existing sewer to the north side of Francis Stewart 

Road. There it would connect into the new sewer system for the new phase of 

the Waverley Heights development. The interceptor trench and parallel sewer 

would be designed in combination with the existing sewer to pick up the 1 in 

100 year storm flow. The sewer in the new phase of development would have 

to be oversized down to the proposed stormwater management pond to carry the 

1 in 100 year storm flow. Figure 5.1 illustrates this concept. It has been 

estimated that the new parallel sewer would have to have a diameter of 975 mm 

and the downstream sewer would have to be oversized to 1200 mm. The 

estimated cost of implementing the parallel sewer and inlet trench/grating has 

been estimated as $150,000 to $175,00. The cost of oversizing the downstream 

sewer should be borne by the developer since the problem occurred as a result 

of poor drainage design in the first phase of the Waverley Heights subdivision. 

2. Improvements to the intersection of Scollard Drive and Francis Stewart Road. 

The crown of the road at the west side of the intersection of Scollard Drive and 

Francis Stewart Road is about 0.5 m higher than the low point at the corner of 




Scollard Drive where the flooding occurs. If the elevation of the road was 

reduced by about 0.6 m and Scollard Road was regraded to the corner, flow 

could continue around the bend and out through the new phase of the 

subdivision to Thompson Creek. It would be necessary to check that sufficient 

capacity exists in the extension of Scollard Drive into the new subdivision to 

carry the full 1 in 100 year flow. Alternatively, a ditch or oversized storm 

sewer would be required. It has been estimated that this approach would cost of 

the order of $75,000 to $100,000 if feasible. Since there are existing services – 

water mains, sanitary sewers, storm sewers, etc. – in the roadway, it may not be 

possible to lower the road surface without violating the minimum cover 

required by that infrastructure. In addition, this approach has the disadvantage 

that because the majority of the bend where the flooding occurs is lined by 

driveways, some flooding up the driveways would likely continue to occur. 

This is because of the momentum of the flow down the steep hill on Scollard 

Drive east of the corner. The duration and extent of flooding would be greatly 

reduced but the entire problem would not be eliminated. 

3. Construct overland flow route to west of flooded area. As indicated earlier, the 

ponded water would naturally tend to spill to the west between the residences 

west of the road. It may be feasible to construct an overland flow swale 

between two of the houses in an easement obtained by the City from the 

property owners (see Figure 5.1). However, based upon the available 

topographic mapping, there is no obvious outlet for such a swale. If it were to 

discharge to Francis Stewart Road beyond the high point between Scollard 

Drive and Eldon Court, it would aggravate the problem at the northwest corner 

of the Eldon Court/Francis Stewart intersection. If it discharged east of the high 

point, the water would simply drain back to the Scollard Drive/Francis Stewart 

intersection and from there back to the problem location. Hence this option 

does not appear feasible. 

4. Do-Nothing. Although the “do nothing” option would entail no cost to the City, 

it would leave the affected residents of Scollard Drive with a drainage problem 

in which flooding of their property occurs relatively frequently. This would not 

meet the City’s objectives of providing a reasonable level of protection against 

flooding for its residents. Hence the “do nothing” option is not an acceptable 

approach. 

Considering the two potentially feasible options (No.1 and No.2), there do not appear to 

be any potential negative environmental impacts of either approach since they both 

involve relatively minor modifications to existing municipal infrastructure away from 




any environmentally sensitive areas. In fact both would result in the storm runoff 

reaching the proposed stormwater management pond to be constructed as part of the 

new phase of the Waverley Heights development. There it will be released at a 

controlled rate to Thompson Creek after receiving water quality treatment. In terms of 

social factors both seem similar in that they will cause some disruption to local traffic 

during construction and some construction noise, etc. Option 1 is the more effective 

technical solution and is more straightforward to implement. Based upon the 

approximate cost estimate and the estimated present value of flood damages, it would 

have a benefit-cost ratio less than 1. Regardless, if the City decides to proceed with 

remediation of this flood problem when considered in the broader context of City-wide 

priorities, Option No. 1 is the recommended preferred alternative for this location. 

5.2 NW CORNER ELDON COURT AND FRANCIS STEWART ROAD 

Figure 5.2 shows the area of flood vulnerability at the corner of Eldon court and Francis 

Stewart road. As discussed in Section 4.6.2.1, this is essentially a case of “nuisance 

flooding” causing no direct or indirect damages. If the City wishes to reduce the 

problem, two solutions which are at a scale proportionate to the nature of the problem, 

would be: a) to add additional catchbasins at the low point to allow the ponded water to 

enter the storm sewer more quickly or b) to create a “curb – cut” at the low point at the 

corner (see Figure 5.2). This would allow the excess water to drain overland to 

Thompson Creek. The City would have to obtain an easement from the private land 

owner west of the intersection and would need to create a swale down to the creek. The 

estimated cost for additional catchbasins (say two) is of the order of $10,000 whereas 

the overland flow route is of the order of $15,000 to $20,000. The additional 

catchbasins would be the preferred option since it would have a lower cost, would not 

involve construction on private property and would continue to direct the storm runoff 

to the small stormwater management facility at the end of Eldon Court. The “donothing” 

alternative is, of course, also available. 

5.3 FRANMOR DRIVE, CHAPEL DRIVE, ABBEY LANE AREA 

As discussed in Sections 4.6.2.1 and 4.7.2, approximately twelve properties in this area 

would suffer “nuisance” flooding for events above the 1 in 10 year storm. Because of 

the super-elevation of the houses above the road, the houses would not be impacted 

until return periods well above the 1 in 100 year storm. The problem appears to occur 

from a generally undersized sewer system and a restricted outlet from the system. 

Given that the estimated present value of flood damages is of the order of $175,000, it 

would not be economically reasonable to consider a general upgrade of the sewer 

network as this would cost of the order of $600,000 to $750,000. Another option which 




could be considered would be to control the inflows to the sewer system at certain 

points to reduce flows in the system to more closely match its capacity. As indicated in 

Figure 5.3, there are potentially three locations where storm runoff might be controlled. 

These are at the outlet from the private condominium development at the east end of 

Dainton Drive and the east end of Fanmore Drive and on a piece of undeveloped land 

on the west side of the intersection of Dainton Drive and Abbey Lane. The latter 

already contains a drainage/soakaway trench on part of its area for the commercial 

development fronting Armour Road west of there. The approach would be based on the 

concept of reducing the 1 in 100 year storm flow to the 1 in 5 year storm flow from the 

areas upstream of these locations. This would be implemented by capturing the 

overland flow by diverting it into surface storage areas and “bleeding” it back into the 

sewer system after the event had passed. Approximately 850 m 3 of storage would be 

needed and could be provided for a cost around $50,000. This could potentially reduce 

the flows for events greater than a 1 in 10 year storm in the flooded street segments to 

below the current 1 in 10 year flow which would keep the major system flow depth 

below curb level. 

One additional point in this system where flooding may be of concern is at the low 

point on Armour Road just south of Whitaker Street. Based upon the detailed 

OTTSWMM modelling, it appears that flooding results from flow converging at the 

low point of Armour Road without sufficient inlet capacity in the catchbasins at that 

location. As indicated on Figure 5.4, an additional double catchbasin connected to a 

pipe which discharges into the swale on the west side of the Road and a curb cut 

discharging to the same location would potentially eliminate the problem. The cost is 

estimated to be in the range of $15,000. 

5.4 ARMOUR ROAD SOUTH OF MOIR STREET 

As identified in Section 4.6.2.1 and 4.7.2, about 5 properties on Armour Road appear to 

suffer from “nuisance flooding” for events up to the 1 in 100 year storm. This appears 

to occur due to a generally undersized sewer system for the drainage area and extent of 

imperviousness. A full upgrade of the system would be cost prohibitive (of the order of 

$500,000 - $600,000) compared to the estimated present value of the AAFD of 

$87,500. Other options which would reduce system inflows are somewhat limited but 

could include redirection of runoff from the roof area/parking lot areas of several 

commercial properties on the east side of Armour Road to storage areas (See 

Figure 5.5). This could potentially reduce the effective imperviousness of the area by 

15% to 20% thereby decreasing the frequency of the nuisance flooding. This approach 

would require the cooperation of the private land owners and might require the City to 

provide a financial incentive. It is difficult to estimate the cost of such measures 




without a detailed review of the drainage on the private property but if feasible might be 

of the order of $10,000 per property. 

5.5 FLOOD PROTECTION RECOMMENDATIONS 

Based upon the evaluation of flood vulnerability and evaluation of flood protection 

options, the following actions are recommended: 

1. The City should consider implementing the preferred alternative (Option No. 1: 

increased inlet capacity and parallel sewer to capture 1 in 100 year storm flow) to 

reduce the frequency of flooding at the corner of Scollard Drive near the intersection 

with Francis Stewart Road. This is the highest priority flood vulnerable area in the 

Thompson Creek study area. 

2. The City should review the potential flood remedial works discussed for the other three 

flood vulnerable areas in the context of the overall City priorities and determine 

whether implementing them is justified. These are all essentially cases of nuisance 

flooding which could be reduced by implementing the measures discussed. 

3. The City does not need to implement any remedial measures along the Thompson 

Creek watercourse to address flood vulnerability from the range of storm events 

considered in this study. However, the City should strongly encourage the Trent Severn 

Waterway to undertake a study to define more accurately the flood risk related to 

releases from the Thompson Creek Dam and to establish a policy on the maximum 

permissible releases from that facility. The study should also include an assessment of 

dam safety and the consequences of a failure of the structure. 

4. Given the existence of this document as a Master Plan under the Municipal Class EA 

(2000), the lack of environment impacts of any of the suggested projects and their 

limited scale/scope, it should be feasible to implement them without further EA 

process. 




APPENDIX G 

FLOW & RAINFALL MONITORING DATA 

14-06605-01-W01 




See Information on Enclosed CD-ROM 

14-06605-01-W01 




APPENDIX H 

OTTHYMO MODEL DOCUMENTATION 

14-06605-01-W01 





14-06605-01-W01 




APPENDIX I 

HEC-RAS MODEL DOCUMENTATION 

14-06605-01-W01 





14-06605-01-W01 




APPENDIX J 

OTTSWMM MODEL DOCUMENTATION 

14-06605-01-W01 





14-06605-01-W01 




OTTSWMM Model Overview 

14-06605-01-W01 




APPENDIX K 

DESIGN RAINFALL INFORMATION 

14-06605-01-W01 


Regulatory (Regional) Storm Event for Peterborough 

Time distribution for Regional Storm for Ontario Zone 3 per MTO Drainage Manual Chart H3-3a 

"TIMMINS STORM EVENT" 

Time 

ending, 

hours Incremental rain Cumulative rain 

(mm) 

(mm) 

1.0 15 15 

2.0 20 35 

3.0 10 45 

4.0 3 48 

5.0 5 53 

6.0 20 73 

7.0 43 116 

8.0 20 136 

9.0 23 159 

10.0 13 172 

11.0 13 185 

12.0 8 193

AES Type 2 Duration = 6 hrs Return period = 100 yrs 

Return period 

100 yr 

Duration 

6 hr 

Volume 

81.73 mm 

Time (min) 

% of duration at 

start of interval 

Interval 

number 

from 

Table9.3 % of total storm 

above rainfall 

Intemsity 

Rain (mm) (mm/hr) 

0 0.00% 0 0 0 

10 2.78% 1 0.33% 0.27 1.634526 

20 5.56% 1 0.33% 0.27 1.634526 

30 8.33% 1 0.33% 0.27 1.634526 

40 11.11% 2 1.00% 0.82 4.903579 

50 13.89% 2 1.00% 0.82 4.903579 

60 16.67% 2 1.00% 0.82 4.903579 

70 19.44% 3 2.67% 2.18 13.07621 

80 22.22% 3 2.67% 2.18 13.07621 

90 25.00% 3 2.67% 2.18 13.07621 

100 27.78% 4 5.00% 4.09 24.5179 

110 30.56% 4 5.00% 4.09 24.5179 

120 33.33% 4 5.00% 4.09 24.5179 

130 36.11% 5 9.33% 7.63 45.76674 

140 38.89% 5 9.33% 7.63 45.76674 

150 41.67% 5 9.33% 7.63 45.76674 

160 44.44% 6 5.00% 4.09 24.5179 

170 47.22% 6 5.00% 4.09 24.5179 

180 50.00% 6 5.00% 4.09 24.5179 

190 52.78% 7 4.00% 3.27 19.61432 

200 55.56% 7 4.00% 3.27 19.61432 

210 58.33% 7 4.00% 3.27 19.61432 

220 61.11% 8 2.67% 2.18 13.07621 

230 63.89% 8 2.67% 2.18 13.07621 

240 66.67% 8 2.67% 2.18 13.07621 

250 69.44% 9 1.67% 1.36 8.172632 

260 72.22% 9 1.67% 1.36 8.172632 

270 75.00% 9 1.67% 1.36 8.172632 

280 77.78% 10 1.00% 0.82 4.903579 

290 80.56% 10 1.00% 0.82 4.903579 

300 83.33% 10 1.00% 0.82 4.903579 

310 86.11% 11 0.33% 0.27 1.634526 

320 88.89% 11 0.33% 0.27 1.634526 

330 91.67% 11 0.33% 0.27 1.634526 

340 94.44% 12 0.33% 0.27 1.634526 

350 97.22% 12 0.33% 0.27 1.634526 

360 100.00% 12 0.33% 0.27 1.634526


Return period 

50 yr 

Duration 

6 hr 

Volume 

76.13 mm 

Time (min) 



Interval 

number 

from 



Intemsity 


0 0.00% 0 0 0 

10 2.78% 1 0.33% 0.25 1.52265 

20 5.56% 1 0.33% 0.25 1.52265 

30 8.33% 1 0.33% 0.25 1.52265 

40 11.11% 2 1.00% 0.76 4.567949 

50 13.89% 2 1.00% 0.76 4.567949 

60 16.67% 2 1.00% 0.76 4.567949 

70 19.44% 3 2.67% 2.03 12.1812 

80 22.22% 3 2.67% 2.03 12.1812 

90 25.00% 3 2.67% 2.03 12.1812 

100 27.78% 4 5.00% 3.81 22.83974 

110 30.56% 4 5.00% 3.81 22.83974 

120 33.33% 4 5.00% 3.81 22.83974 

130 36.11% 5 9.33% 7.11 42.63419 

140 38.89% 5 9.33% 7.11 42.63419 

150 41.67% 5 9.33% 7.11 42.63419 

160 44.44% 6 5.00% 3.81 22.83974 

170 47.22% 6 5.00% 3.81 22.83974 

180 50.00% 6 5.00% 3.81 22.83974 

190 52.78% 7 4.00% 3.05 18.27179 

200 55.56% 7 4.00% 3.05 18.27179 

210 58.33% 7 4.00% 3.05 18.27179 

220 61.11% 8 2.67% 2.03 12.1812 

230 63.89% 8 2.67% 2.03 12.1812 

240 66.67% 8 2.67% 2.03 12.1812 

250 69.44% 9 1.67% 1.27 7.613248 

260 72.22% 9 1.67% 1.27 7.613248 

270 75.00% 9 1.67% 1.27 7.613248 

280 77.78% 10 1.00% 0.76 4.567949 

290 80.56% 10 1.00% 0.76 4.567949 

300 83.33% 10 1.00% 0.76 4.567949 

310 86.11% 11 0.33% 0.25 1.52265 

320 88.89% 11 0.33% 0.25 1.52265 

330 91.67% 11 0.33% 0.25 1.52265 

340 94.44% 12 0.33% 0.25 1.52265 

350 97.22% 12 0.33% 0.25 1.52265 

360 100.00% 12 0.33% 0.25 1.52265


Return period 

25 yr 

Duration 

6 hr 

Volume 

65.65 mm 

Time (min) 



Interval 

number 

from 



Intemsity 


0 0.00% 0 0 0 

10 2.78% 1 0.33% 0.22 1.312956 

20 5.56% 1 0.33% 0.22 1.312956 

30 8.33% 1 0.33% 0.22 1.312956 

40 11.11% 2 1.00% 0.66 3.938869 

50 13.89% 2 1.00% 0.66 3.938869 

60 16.67% 2 1.00% 0.66 3.938869 

70 19.44% 3 2.67% 1.75 10.50365 

80 22.22% 3 2.67% 1.75 10.50365 

90 25.00% 3 2.67% 1.75 10.50365 

100 27.78% 4 5.00% 3.28 19.69435 

110 30.56% 4 5.00% 3.28 19.69435 

120 33.33% 4 5.00% 3.28 19.69435 

130 36.11% 5 9.33% 6.13 36.76278 

140 38.89% 5 9.33% 6.13 36.76278 

150 41.67% 5 9.33% 6.13 36.76278 

160 44.44% 6 5.00% 3.28 19.69435 

170 47.22% 6 5.00% 3.28 19.69435 

180 50.00% 6 5.00% 3.28 19.69435 

190 52.78% 7 4.00% 2.63 15.75548 

200 55.56% 7 4.00% 2.63 15.75548 

210 58.33% 7 4.00% 2.63 15.75548 

220 61.11% 8 2.67% 1.75 10.50365 

230 63.89% 8 2.67% 1.75 10.50365 

240 66.67% 8 2.67% 1.75 10.50365 

250 69.44% 9 1.67% 1.09 6.564782 

260 72.22% 9 1.67% 1.09 6.564782 

270 75.00% 9 1.67% 1.09 6.564782 

280 77.78% 10 1.00% 0.66 3.938869 

290 80.56% 10 1.00% 0.66 3.938869 

300 83.33% 10 1.00% 0.66 3.938869 

310 86.11% 11 0.33% 0.22 1.312956 

320 88.89% 11 0.33% 0.22 1.312956 

330 91.67% 11 0.33% 0.22 1.312956 

340 94.44% 12 0.33% 0.22 1.312956 

350 97.22% 12 0.33% 0.22 1.312956 

360 100.00% 12 0.33% 0.22 1.312956


Return period 

10 yr 

Duration 

6 hr 

Volume 

57.49 mm 

Time (min) 



Interval 

number 

from 



Intemsity 


0 0.00% 0 0 0 

10 2.78% 1 0.33% 0.19 1.149837 

20 5.56% 1 0.33% 0.19 1.149837 

30 8.33% 1 0.33% 0.19 1.149837 

40 11.11% 2 1.00% 0.57 3.449511 

50 13.89% 2 1.00% 0.57 3.449511 

60 16.67% 2 1.00% 0.57 3.449511 

70 19.44% 3 2.67% 1.53 9.198695 

80 22.22% 3 2.67% 1.53 9.198695 

90 25.00% 3 2.67% 1.53 9.198695 

100 27.78% 4 5.00% 2.87 17.24755 

110 30.56% 4 5.00% 2.87 17.24755 

120 33.33% 4 5.00% 2.87 17.24755 

130 36.11% 5 9.33% 5.37 32.19543 

140 38.89% 5 9.33% 5.37 32.19543 

150 41.67% 5 9.33% 5.37 32.19543 

160 44.44% 6 5.00% 2.87 17.24755 

170 47.22% 6 5.00% 2.87 17.24755 

180 50.00% 6 5.00% 2.87 17.24755 

190 52.78% 7 4.00% 2.30 13.79804 

200 55.56% 7 4.00% 2.30 13.79804 

210 58.33% 7 4.00% 2.30 13.79804 

220 61.11% 8 2.67% 1.53 9.198695 

230 63.89% 8 2.67% 1.53 9.198695 

240 66.67% 8 2.67% 1.53 9.198695 

250 69.44% 9 1.67% 0.96 5.749185 

260 72.22% 9 1.67% 0.96 5.749185 

270 75.00% 9 1.67% 0.96 5.749185 

280 77.78% 10 1.00% 0.57 3.449511 

290 80.56% 10 1.00% 0.57 3.449511 

300 83.33% 10 1.00% 0.57 3.449511 

310 86.11% 11 0.33% 0.19 1.149837 

320 88.89% 11 0.33% 0.19 1.149837 

330 91.67% 11 0.33% 0.19 1.149837 

340 94.44% 12 0.33% 0.19 1.149837 

350 97.22% 12 0.33% 0.19 1.149837 

360 100.00% 12 0.33% 0.19 1.149837


Return period 

5 yr 

Duration 

6 hr 

Volume 

48.65 mm 

Time (min) 



Interval 

number 

from 



Intemsity 


0 0.00% 0 0 0 

10 2.78% 1 0.33% 0.16 0.972924 

20 5.56% 1 0.33% 0.16 0.972924 

30 8.33% 1 0.33% 0.16 0.972924 

40 11.11% 2 1.00% 0.49 2.918771 

50 13.89% 2 1.00% 0.49 2.918771 

60 16.67% 2 1.00% 0.49 2.918771 

70 19.44% 3 2.67% 1.30 7.783389 

80 22.22% 3 2.67% 1.30 7.783389 

90 25.00% 3 2.67% 1.30 7.783389 

100 27.78% 4 5.00% 2.43 14.59385 

110 30.56% 4 5.00% 2.43 14.59385 

120 33.33% 4 5.00% 2.43 14.59385 

130 36.11% 5 9.33% 4.54 27.24186 

140 38.89% 5 9.33% 4.54 27.24186 

150 41.67% 5 9.33% 4.54 27.24186 

160 44.44% 6 5.00% 2.43 14.59385 

170 47.22% 6 5.00% 2.43 14.59385 

180 50.00% 6 5.00% 2.43 14.59385 

190 52.78% 7 4.00% 1.95 11.67508 

200 55.56% 7 4.00% 1.95 11.67508 

210 58.33% 7 4.00% 1.95 11.67508 

220 61.11% 8 2.67% 1.30 7.783389 

230 63.89% 8 2.67% 1.30 7.783389 

240 66.67% 8 2.67% 1.30 7.783389 

250 69.44% 9 1.67% 0.81 4.864618 

260 72.22% 9 1.67% 0.81 4.864618 

270 75.00% 9 1.67% 0.81 4.864618 

280 77.78% 10 1.00% 0.49 2.918771 

290 80.56% 10 1.00% 0.49 2.918771 

300 83.33% 10 1.00% 0.49 2.918771 

310 86.11% 11 0.33% 0.16 0.972924 

320 88.89% 11 0.33% 0.16 0.972924 

330 91.67% 11 0.33% 0.16 0.972924 

340 94.44% 12 0.33% 0.16 0.972924 

350 97.22% 12 0.33% 0.16 0.972924 

360 100.00% 12 0.33% 0.16 0.972924


Return period 

2 yr 

Duration 

6 hr 

Volume 

37.36 mm 

Time (min) 



Interval 

number 

from 



Intemsity 


0 0.00% 0 0 0 

10 2.78% 1 0.33% 0.12 0.747284 

20 5.56% 1 0.33% 0.12 0.747284 

30 8.33% 1 0.33% 0.12 0.747284 

40 11.11% 2 1.00% 0.37 2.241853 

50 13.89% 2 1.00% 0.37 2.241853 

60 16.67% 2 1.00% 0.37 2.241853 

70 19.44% 3 2.67% 1.00 5.978275 

80 22.22% 3 2.67% 1.00 5.978275 

90 25.00% 3 2.67% 1.00 5.978275 

100 27.78% 4 5.00% 1.87 11.20927 

110 30.56% 4 5.00% 1.87 11.20927 

120 33.33% 4 5.00% 1.87 11.20927 

130 36.11% 5 9.33% 3.49 20.92396 

140 38.89% 5 9.33% 3.49 20.92396 

150 41.67% 5 9.33% 3.49 20.92396 

160 44.44% 6 5.00% 1.87 11.20927 

170 47.22% 6 5.00% 1.87 11.20927 

180 50.00% 6 5.00% 1.87 11.20927 

190 52.78% 7 4.00% 1.49 8.967413 

200 55.56% 7 4.00% 1.49 8.967413 

210 58.33% 7 4.00% 1.49 8.967413 

220 61.11% 8 2.67% 1.00 5.978275 

230 63.89% 8 2.67% 1.00 5.978275 

240 66.67% 8 2.67% 1.00 5.978275 

250 69.44% 9 1.67% 0.62 3.736422 

260 72.22% 9 1.67% 0.62 3.736422 

270 75.00% 9 1.67% 0.62 3.736422 

280 77.78% 10 1.00% 0.37 2.241853 

290 80.56% 10 1.00% 0.37 2.241853 

300 83.33% 10 1.00% 0.37 2.241853 

310 86.11% 11 0.33% 0.12 0.747284 

320 88.89% 11 0.33% 0.12 0.747284 

330 91.67% 11 0.33% 0.12 0.747284 

340 94.44% 12 0.33% 0.12 0.747284 

350 97.22% 12 0.33% 0.12 0.747284 

360 100.00% 12 0.33% 0.12 0.747284

AES Type 2 Duration = 1 

Duration 

Volume 

Time (min) 

1 hr 

120.00 mm 


Interval 

number 

from 

Table9.3 

Intemsity 

start of interval above Rain (mm) (mm/hr) 

0 0.00% 0 0.0 

5 8.33% 1 1.20 14.4 

10 16.67% 3 3.60 43.2 

15 25.00% 8 9.60 115.2 

20 33.33% 15 18.00 216.0 

25 41.67% 28 33.60 403.2 

30 50.00% 15 18.00 216.0 

35 58.33% 12 14.40 172.8 

40 66.67% 8 9.60 115.2 

45 75.00% 5 6.00 72.0 

50 83.33% 3 3.60 43.2 

55 91.67% 1 1.20 14.4 

60 100.00% 1 1.20 14.4 

100 120.00


Duration 

Volume 

Time (min) 

1 hr 

100.00 mm 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 1.00 12.0 

10 16.67% 3 3.00 36.0 

15 25.00% 8 8.00 96.0 

20 33.33% 15 15.00 180.0 

25 41.67% 28 28.00 336.0 

30 50.00% 15 15.00 180.0 

35 58.33% 12 12.00 144.0 

40 66.67% 8 8.00 96.0 

45 75.00% 5 5.00 60.0 

50 83.33% 3 3.00 36.0 

55 91.67% 1 1.00 12.0 

60 100.00% 1 1.00 12.0 

100 100.00


Duration 

Volume 

Time (min) 

1 hr 

80.00 mm 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 0.80 9.6 

10 16.67% 3 2.40 28.8 

15 25.00% 8 6.40 76.8 

20 33.33% 15 12.00 144.0 

25 41.67% 28 22.40 268.8 

30 50.00% 15 12.00 144.0 

35 58.33% 12 9.60 115.2 

40 66.67% 8 6.40 76.8 

45 75.00% 5 4.00 48.0 

50 83.33% 3 2.40 28.8 

55 91.67% 1 0.80 9.6 

60 100.00% 1 0.80 9.6 

100 80.00


Duration 

Volume 

Time (min) 

1 hr 

60.00 mm 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 0.60 7.2 

10 16.67% 3 1.80 21.6 

15 25.00% 8 4.80 57.6 

20 33.33% 15 9.00 108.0 

25 41.67% 28 16.80 201.6 

30 50.00% 15 9.00 108.0 

35 58.33% 12 7.20 86.4 

40 66.67% 8 4.80 57.6 

45 75.00% 5 3.00 36.0 

50 83.33% 3 1.80 21.6 

55 91.67% 1 0.60 7.2 

60 100.00% 1 0.60 7.2 

100 60.00


Duration 

Volume 

Time (min) 

1 hr 

40.00 mm 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 0.40 4.8 

10 16.67% 3 1.20 14.4 

15 25.00% 8 3.20 38.4 

20 33.33% 15 6.00 72.0 

25 41.67% 28 11.20 134.4 

30 50.00% 15 6.00 72.0 

35 58.33% 12 4.80 57.6 

40 66.67% 8 3.20 38.4 

45 75.00% 5 2.00 24.0 

50 83.33% 3 1.20 14.4 

55 91.67% 1 0.40 4.8 

60 100.00% 1 0.40 4.8 

100 40.00


Return period 

100 yr 

Duration 

1 hr 

Volume 

56.25 mm 

Time (min) 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 0.56 6.7 

10 16.67% 3 1.69 20.2 

15 25.00% 8 4.50 54.0 

20 33.33% 15 8.44 101.2 

25 41.67% 28 15.75 189.0 

30 50.00% 15 8.44 101.2 

35 58.33% 12 6.75 81.0 

40 66.67% 8 4.50 54.0 

45 75.00% 5 2.81 33.7 

50 83.33% 3 1.69 20.2 

55 91.67% 1 0.56 6.7 

60 100.00% 1 0.56 6.7 

100 56.25 675.00


Return period 

50 yr 

Duration 

1 hr 

Volume 

51.66 mm 

Time (min) 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 0.52 6.2 

10 16.67% 3 1.55 18.6 

15 25.00% 8 4.13 49.6 

20 33.33% 15 7.75 93.0 

25 41.67% 28 14.46 173.6 

30 50.00% 15 7.75 93.0 

35 58.33% 12 6.20 74.4 

40 66.67% 8 4.13 49.6 

45 75.00% 5 2.58 31.0 

50 83.33% 3 1.55 18.6 

55 91.67% 1 0.52 6.2 

60 100.00% 1 0.52 6.2 

100 51.66


Return period 

25 yr 

Duration 

1 hr 

Volume 

45.53 mm 

Time (min) 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 0.46 5.5 

10 16.67% 3 1.37 16.4 

15 25.00% 8 3.64 43.7 

20 33.33% 15 6.83 81.9 

25 41.67% 28 12.75 153.0 

30 50.00% 15 6.83 81.9 

35 58.33% 12 5.46 65.6 

40 66.67% 8 3.64 43.7 

45 75.00% 5 2.28 27.3 

50 83.33% 3 1.37 16.4 

55 91.67% 1 0.46 5.5 

60 100.00% 1 0.46 5.5 

100 45.53


Return period 

10 yr 

Duration 

1 hr 

Volume 

38.96 mm 

Time (min) 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 0.39 4.7 

10 16.67% 3 1.17 14.0 

15 25.00% 8 3.12 37.4 

20 33.33% 15 5.84 70.1 

25 41.67% 28 10.91 130.9 

30 50.00% 15 5.84 70.1 

35 58.33% 12 4.68 56.1 

40 66.67% 8 3.12 37.4 

45 75.00% 5 1.95 23.4 

50 83.33% 3 1.17 14.0 

55 91.67% 1 0.39 4.7 

60 100.00% 1 0.39 4.7 

100 38.96


Return period 

5 yr 

Duration 

1 hr 

Volume 

32.26 mm 

Time (min) 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 0.32 3.9 

10 16.67% 3 0.97 11.6 

15 25.00% 8 2.58 31.0 

20 33.33% 15 4.84 58.1 

25 41.67% 28 9.03 108.4 

30 50.00% 15 4.84 58.1 

35 58.33% 12 3.87 46.5 

40 66.67% 8 2.58 31.0 

45 75.00% 5 1.61 19.4 

50 83.33% 3 0.97 11.6 

55 91.67% 1 0.32 3.9 

60 100.00% 1 0.32 3.9 

100 32.26


Return period 

2 yr 

Duration 

1 hr 

Volume 

23.75 mm 

Time (min) 


Interval 

number 

from 

Table9.3 

Intemsity 


0 0.00% 0 0.0 

5 8.33% 1 0.24 2.9 

10 16.67% 3 0.71 8.6 

15 25.00% 8 1.90 22.8 

20 33.33% 15 3.56 42.8 

25 41.67% 28 6.65 79.8 

30 50.00% 15 3.56 42.8 

35 58.33% 12 2.85 34.2 

40 66.67% 8 1.90 22.8 

45 75.00% 5 1.19 14.3 

50 83.33% 3 0.71 8.6 

55 91.67% 1 0.24 2.9 

60 100.00% 1 0.24 2.9 

100 23.75

Peterborough Rainfall July 14/15 2004 

Thompson Creek Average Amounts 

Time Rain (mm) 

0 0.00 

10 0.00 

20 0.00 

30 0.00 

40 0.11 

50 0.63 

60 1.00 

70 0.90 

80 1.09 

90 0.33 

100 0.20 

110 0.22 

120 0.17 

130 0.13 

140 0.14 

150 0.13 

160 0.14 

170 0.07 

180 0.03 

190 0.01 

200 0.00 

210 0.00 

220 0.00 

230 0.01 

240 0.04 

250 0.11 

260 0.11 

270 0.12 

280 0.01 

290 0.00 

300 0.00 

310 0.01 

320 0.03 

330 0.02 

340 0.00 

350 0.01 

360 0.02 

370 0.01 

380 0.01 

390 0.01 

400 0.00 

410 0.00 

420 0.00 

430 0.00 

440 0.00 

450 0.00 

460 0.00 

470 0.00

480 0.00 

490 0.03 

500 0.26 

510 0.54 

520 0.03 

530 0.00 

540 0.00 

550 0.00 

560 0.00 

570 0.00 

580 0.00 

590 0.00 

600 0.00 

610 0.00 

620 0.00 

630 0.00 

640 0.00 

650 0.00 

660 0.00 

670 0.00 

680 0.00 

690 0.69 

700 2.75 

710 2.27 

720 0.12 

730 0.00 

740 0.02 

750 0.00 

760 0.00 

770 0.02 

780 0.02 

790 0.05 

800 0.08 

810 0.05 

820 0.02 

830 0.00 

840 0.00 

850 0.00 

860 0.00 

870 0.00 

880 0.01 

890 0.00 

900 0.01 

910 0.05 

920 0.18 

930 0.79 

940 2.70 

950 3.30 

960 1.35 

970 0.73 

980 0.52

990 0.50 

1000 0.35 

1010 0.36 

1020 0.31 

1030 0.22 

1040 0.23 

1050 0.23 

1060 0.11 

1070 0.14 

1080 0.11 

1090 0.10 

1100 0.08 

1110 0.15 

1120 0.57 

1130 0.82 

1140 0.07 

1150 0.20 

1160 0.18 

1170 0.13 

1180 0.13 

1190 0.14 

1200 0.49 

1210 1.64 

1220 2.40 

1230 0.78 

1240 0.25 

1250 0.29 

1260 0.79 

1270 1.33 

1280 2.21 

1290 2.62 

1300 2.02 

1310 4.17 

1320 4.73 

1330 1.32 

1340 1.20 

1350 1.24 

1360 2.07 

1370 3.14 

1380 4.26 

1390 3.26 

1400 2.50 

1410 2.77 

1420 4.38 

1430 3.44 

1440 4.28 

1450 4.04 

1460 3.49 

1470 2.92 

1480 3.17 

1490 3.18

1500 2.97 

1510 2.43 

1520 2.25 

1530 2.06 

1540 1.28 

1550 0.46 

1560 0.51 

1570 1.27 

1580 2.00 

1590 1.08 

1600 1.44 

1610 1.85 

1620 1.30 

1630 1.29 

1640 0.77 

1650 0.51 

1660 0.63 

1670 0.51 

1680 0.25 

1690 0.22 

1700 0.17 

1710 0.04 

1720 0.04 

1730 0.06 

1740 0.08 

1750 0.00 

1760 0.02 

1770 0.01 

1780 0.00 

1790 0.00 

1800 0.00 

1810 0.00 

1820 0.00 

1830 0.00 

1840 0.00 

1850 0.00 

1860 0.00 

1870 0.01 

1880 0.04 

1890 0.02 

1900 0.02 

1910 0.25 

1920 0.75 

1930 0.47 

1940 0.33 

1950 0.25 

1960 0.25 

1970 0.22 

1980 0.20 

1990 0.17 

2000 0.29

2010 0.20 

2020 0.08 

2030 0.05 

2040 0.00 

2050 0.00 

2060 0.00 

2070 0.01 

2080 0.05 

2090 0.03 

2100 0.02 

2110 0.02 

2120 0.05 

2130 0.14 

2140 0.01 

2150 0.16 

2160 0.64 

2170 0.47 

2180 0.13 

2190 0.02 

2200 0.04 

2210 0.02 

2220 0.00 

2230 0.01 

2240 0.02 

2250 0.00 

2260 0.00 

2270 0.00 

2280 0.00 

2290 0.00 

2300 0.00 

2310 0.00 

2320 0.00 

2330 0.00 

2340 0.03 

2350 0.10 

2360 0.10 

2370 0.08 

2380 0.07 

2390 0.12 

2400 0.08 

2410 0.08 

2420 0.17 

2430 0.12 

2440 0.05 

2450 0.03 

2460 0.02 

2470 0.00 

2480 0.01 

2490 0.01 

2500 0.00

LEGEND 

EXISTING CATCHBASIN 

LOCATION 

EXISTING STM SEWER 

EXISTING MANHOLE 

LOCATION 

POTENTIAL STREET 

FLOODING AREA - 

100-YEAR 1-HOUR AES 

DESIGN STORM 



JULY 2004 


STORM 

EXISTING BUILDING 

MAJOR FLOW DIRECTION 

0 10 30 20 40 50m 

DWG SF-1_SF-2.dwg SUBDIVISION S: \14-41\14\06605-01-W01\ May 10, 2007 - 3:13pm

LEGEND 

EXISTING CATCHBASIN 

LOCATION 

EXISTING STM SEWER 

EXISTING MANHOLE 

LOCATION 



100-YEAR 1-HOUR AES 

DESIGN STORM 



JULY 2004 


STORM 

EXISTING BUILDING 

MAJOR FLOW DIRECTION 

0 10 30 20 40 50m 

DWG SF-1_SF-2.dwg EXTENDED AREA S: \14-41\14\06605-01-W01\ May 10, 2007 - 3:14pm

Thompson Creek Flood Study Report - City of Peterborough

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