Flood Risk in the Dixie-Dundas Area

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Learn about how you can be better prepared for flooding from industry professionals. Visit their booths for resources, advice and more!

Toronto and Region Conservation Authority 1

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Flood Risk in the Dixie-Dundas Area

Presented by TRCA and the City of Mississauga

March 2, 2020

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Presentation Outline

• Understanding potential flooding in Mississauga

• How are flood risks managed

• Mississauga's mitigation projects

• What can you do now, from the City's emergency management office

• TRCA's flood management resources

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Flooding has been a concern for residents of the Toronto area since the area was first settled. On October 15 and 16, 1954, Toronto received 210 mm of rain in a 12-hour period. For our region, Hurricane Hazel remains the most severe flood in recorded history. Recognizing the importance of flood management, the Provincial government amended the Conservation Authorities Act to enable an Authority to acquire lands for recreation and conservation purposes.

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How are floodplain and flood risk maps made?

Models of real (and Hypothetical Storms Existing topography planned) land-cover

This Photo by Unknown Author is licensed under CC BY-NC Toronto and Region Conservation Authority 5

How are flood maps made? TRCA must ensure that if development occurs in areas that are likely to experience flooding and erosion that it is properly permitted in order to decrease the risk of loss of life, personal injury and property damage. Building in a floodplain can have major consequences and can also affect neighboring properties by changing the physical characteristics of the valley or flood plain, or drainage to these properties. Developing flood plain maps requires detailed river and floodplain information and a lot of science and engineering. The maps are created based on canned scenarios to help engineers understand the worst-case scenario for development and planning purposes. Flood maps are not necessarily based on floods experienced in the past.

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Flood Protection near Dixie-Dundas

The Dixie-Dundas Channel and Dyke work together to provide flood protection to the City of Mississauga, specifically to the Dixie-Dundas neighbourhood, by reducing peak flows during flood events. Toronto and Region Conservation Authority 6

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The Dixie-Dundas cluster is subject to flooding due to a combination of capacity constraints in the river channel and backwater from multiple culvert crossings. Located on Little Etobicoke Creek, this cluster is near the intersection of Dixie Road and Dundas Street East in the city of Mississauga. It is a provincially designated Special Policy Area (SPA). The urbanized nature of the Little Etobicoke Creek watershed makes this cluster susceptible to flooding from intense summer thunderstorms. Significant flooding occurred during the July 8, 2013 storm when flows overtopped the engineered channel and began flowing south along Queen Frederica Drive.

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Flooding can happen any time of year Summer Fall • Thunderstorms with • Seasonal weather systems significant rainfall – within – large wet weather such as a short period of time, tropical storms, can last intense localized several days. Prolonged downpours from and heavy precipitation on thunderstorms can produce top of already saturated flash flooding. soils causes rivers to rise.

Spring Winter • • Spring freshet – Ice jams – when a rise in accumulation of snow water level or a thaw in the during the winter season ice breaks into large can lead to flooding during chunks, these chunks can the early spring, if become jammed at bridges conditions are right. When or other obstructions. The temperatures rise, snow rise will become backed up melts and turns to runoff. Toronto and Regionand canConservation overflow Authority its banks.8

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Cities & Conservation Authorities Work Together Conservation Authorities

• Monitor watershed and weather conditions and operate a flood forecasting and warning system • Issue Flood Messages • Operate Conservation Authority dams and flood control structures • Provide technical advice to municipalities • Maintain communications with municipalities and other agencies

Municipal Role

• Notify appropriate municipal officials, departments and agencies. • Determine the appropriate response and deploy municipal resources to protect life and property. • If required, declare a flood emergency and implement their emergency response plan.

• Request provincial assistanceToronto if needed and Region Conservation Authority 9

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Not all flooding comes from a river…

Private drainage and surface water Contact your insurance representative for any property related damage due to flooding. Make Sanitary sewer back up services sure your policy covers all types of flooding. Most backups occur when the sewer pipe that runs from your home to the Region’s main sanitary sewer pipe is blocked with items such as roots or Residents near watercourses grease. A blockage in the sewer pipe may Properties and structures located within a cause wastewater to back up into your floodplain are especially susceptible to flooding basement from the floor drain. due to the rise in water levels resulting from large, infrequent storm events.

Overland Flow/urban flooding Heavy downpour can cause storm drainage systems to overflow. Water may spill onto the property and enter the building through the basement windows or other openings.

Free Images fromhttps://pixabay.com/ Catch Basin also known as a storm drain inlet or curb inlet at street level where storm water enters the catch basin.

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Environmental Services Greg Frew, P.Eng. Acting Manager of Stormwater Projects & Approvals, Environmental Services

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Types of flooding

 Riverine (fluvial) flooding occurs when water levels in a river rise and overflow its banks, spilling onto adjacent lands. Conservation Authorities identify riverine flood risks

 Urban (pluvial) flooding occurs when a © Reuters/Andy Clark heavy rainfall event exceeds the capacity of the storm sewer system, causing the water to pond within the roadway. Urban storm infrastructure is the responsibility of municipalities.

Important Difference: Urban flooding can occur anywhere, independent of a water © Todd Yates body

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Urban Storm Drainage System  Storm sewers (minor system) – drain storm runoff from most everyday storms up to the 10-year storm (1 in 10 chance that it will occur in a given year).

 Roadways (major system) – store and drain excess runoff when the storm sewer capacity is exceeded during major storm events.

 Important: Temporary ponding is expected during these major storm events.

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Looking for Solutions: City of Mississauga Flood Studies

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1. Dixie-Dundas Flood Mitigation Study

Objective: review options to reduce or eliminate the spill of riverine floodwaters from Little Etobicoke Creek near Dixie-Dundas

Timing: • Phase 1 Feasibility –2019/20 • Phase 2 Municipal Environmental Assessment Study – 2020/2021 • Upcoming Open House #1- Late spring 2020 Flood spill from Little Etobicoke Creek

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2. Little Etobicoke Creek Flood Evaluation Study Objective: review options to reduce the impacts of urban flooding in the Little Etobicoke Creek watershed

Underground stormwater storage galleries Timing: • Phase 1 Define flood risks – 2017/2018 • Phase 2 Assessment of flood reduction solutions – 2019/2020

Storm sewer improvement works • Upcoming Open House #2 – late spring 2020

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Flood Preparedness Ben Gallagher (A) Emergency Management Specialist Office of Emergency Management

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Flood Preparedness There are actions you can take to reduce the risk of flooding, including: • Wastewater back-up flooding • Install sanitary wastewater backflow preventer valve • Disconnect roof downspouts from wastewater lateral pipe • Storm Sewer back-up flooding • Improve lot grading • Clean leaves and other debris from eaves troughs • Do not pour or flush items into drains or toilets that can cause blockages (grease, fats, oil, wipes)

Some insurance companies offer overland flooding insurance. Contact your insurance broker to see whether this is available in your area.

Please visit the Office of Emergency Management table for more information on flooding preparedness and recovery

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Insurance Tips

It is recommended to: • Have homeowners or tenants insurance • Be familiar with your policy coverage • Know the 24/7 contact number to start a claim • Inventory your belongings

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General Emergency Preparedness Households are expected to be able to cope on their own for 72 hours (3 days) during emergencies.

You can prepare yourself and family by following the three steps to emergency preparedness:

1. Make a Plan 2. Build a Kit 3. Stay Informed

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General Emergency Preparedness More information on emergency preparedness:

City of Mississauga http://www.mississauga.ca A digital handbook with information Region of Peel specific to Mississauga was created https://www.peelregion.ca to help you understand and prepare for flooding: trca.ca/flood-risk- Emergency Management Ontario dixie-dundas https://www.ontario.ca/emo

Public Safety Canada https://www.getprepared.gc.ca

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Who to call during a flood?

• If you are in danger or there is a threat to life and safety, call 911 immediately. • If you see any potential damage to your property, call your insurance representative as soon as possible. • For hydro-related questions, contact Alectra Customer Service at 1-877-963-6900 (Press 2). • To report localized flooding on municipal roads, blocked catch basins or municipal infrastructure, contact the City of Mississauga by dialing 3-1-1 (outside city limits: 905- 615-4311) or by emailing [email protected]. • To report river flooding from the Etobicoke Creek, leave a voicemail on the TRCA floodline at 416-661-6514. A flood duty officer will return your call.

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For important Mississauga updates, follow @CityMississauga Toronto and Region Conservation Authority 23

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Site specific response planning

TRCA and the City of Mississauga work together on emergency planning, and the information we have from our modelling is used to inform contingency plans

Toronto and Region Conservation Authority

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Continued Flood Monitoring

TRCA has a network of real-time river and rain gauges across the GTA to:

• Monitor the water levels in specific stream and behind dams • Measure how much precipitation has fallen

beta.trcagauging.ca

Nearby Stream & rain gauges

Stream Gauge:

• HY098 - Little Etobicoke

Precipitation Gauge:

• HY099 – Rathwood

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Thank you

Information presented today can be accessed online at: trca.ca/flood-risk-flood-dixie-dundas

www.trca.ca/flood @TRCA_Flood

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