Response during Ice Jam
The response during this flood by the City of Brampton and CVC was immediate and commensurate, especially given the changing weather conditions throughout the event and the inherent challenges associated with ice management. There were no injuries amongst residents, City staff and contractors working on the site.
CVC compiled the following lessons learned regarding ice jams:
1.
Prediction: It is impossible to predict when or where an ice jam will occur. CVC staff can reasonably predict when weather conditions are ideal for river ice break-up; however, what the ice will do after breakup cannot be predicted. Ongoing field monitoring of conditions using flow gauges and by patrol staff is important.
2.
Intervention &
Blasting: The best time to blast an ice jam is right after the jam has formed because there will be sufficient flow behind the jam to clear the jam. However, unstable ice jams are unsafe for workers. Furthermore, blasting contractors have a specialized skillset and are not prevalent throughout the GTA. CVC used to perform river ice blasting as recently as the 1990s but no longer undertakes this work due to their changed mandate and budgets. The lag time for any qualified contractors to arrive on site means that the ideal blasting window is usually passed before any blasting work can start.
It is important to note that blasting ice jams can send the problem downstream if the broken up ice creates another jam. In the case of the February 2022 event, staff were mindful of this risk to Highway 407 and the City of Mississauga. City staff elected not to blast this ice jam but it was considered as a “last resort” option.
3.
Release without
Intervention: If an ice jam develops and no mitigation efforts are applied, the following scenarios can unfold:
- Ice jams can release by themselves.
- Ice jams can release when a large influx of flows come from upstream.
- Ice jams can become grounded/stuck when the water levels decline. This can persist for several days or weeks depending on conditions.
- Ice jams can melt away. The water temperature appears to have a larger influence on the rate of melt compared to air temperature.
Disaster Relief
After a natural disaster, people may need help to cover the costs of cleaning, repairing and replacing essential property, so their lives can get back to normal. Under the Ministry of Municipal Affairs and Housing, the
Disaster Recovery Assistance for Ontarians program provides financial assistance to individuals, small owner-operated businesses, farmers and not-for-profit organizations to help cover emergency expenses, repairs, or replacement of essential property after a natural disaster.
In response to the February 2022 flood event in the Churchville area, the Ontario government decided to activate the program in support of Brampton residents and families who were impacted by this incident.
Debriefing
City staff and CVC debriefed the February 2022 event to assess the severity and causes of flooding. The flooding appeared to have three major causes:
1. Legacy floodplain policies in Churchville
Previous policies allowed development within the Regulatory floodplain in Churchville. Today there are approximately 50 buildings in the floodplain and at least 34 floods have occurred since 1922. High water from the Credit River will always look to occupy the lowest ground nearby, including the Churchville neighbourhood.
2. Ice break-up and jamming in the river elbow
Peak flows along most of the Credit River during the February 2022 event were equivalent to approximately a 1:10-year flood. A 1:10-year flood would normally (in the absence of ice jams) cause only minor flooding along the Credit River in low-lying areas. Peak water levels in Churchville were higher than the 1:100-year flood during the event because of the ice jam at the first elbow downstream of the Churchville Road bridge.
3. Failure of two storm sewer outfalls through the existing berms
Outfall failures at locations 4 and 5 (Figure 1) allowed flooding in the Credit River to back up into the roads and properties behind the berms and floodwalls.
A small part of the flood protection berm was overtopped at the location shown in Figure 1 but this was a minimal contribution to flooding compared to the sewer backup and surcharging.
Post-Flood Restoration
City staff restored the park, roads, swales, and bridge throughout the neighbourhood after the ice jam event. Additional details on the restoration work undertaken after the ice jam and additional work since then are provided in the
attached table.
Condition of Flood Control Infrastructure
City staff and contractors inspected the storm sewers, culverts, flap gates, and ditches after the ice jam to identify maintenance needs. The failures at locations 4 and 5 in Figure 1 appear to have occurred due to jammed flap gates and bolts securing manhole lids being sheared off. City staff are replacing the flap gates with new backflow prevention valves that are less prone to clogging or jamming. In addition, the manhole lids have been replaced and bolted. Storm sewers and culverts have also been flushed which will help reduce the risk of clogging the valves. City staff are assessing whether to repair or replace the culvert at location 2 in Figure 1.
In addition, annual operational programs moving forward will include more frequent:
- Inspection and hand-removal of debris at outfalls;
- CCTV of storm sewers;
- Flushing culverts, storm sewers, and catchbasin leads; and
- Mowing vegetation at outfalls.
Next Steps
In addition to ongoing operational improvements, as well as the installation of improved flap gates to replace previous ones, the City will be looking at approaches to reduce flood risk for the long term.
This includes:
Structural Assessment of Existing Flood Protection
The City has retained a qualified consultant to inspect the existing floodwalls and berms, assess their structural condition, and identify any improvements needed to restore full functionality and integrity. Inspections are expected to be completed by Q3 2023. Approximately 40% of the berms and floodwalls are across private property. Given the absence of any easements to allow the City to enter onto private property to access these segments of the berms and floodwalls, City staff have contacted these property owners requesting permission to access their property. Additional information about this project is available here.
Identification and Assessment of Further Flood Mitigation Measures
The City will begin a Municipal Class Environmental Assessment (MCEA) in Spring 2024 to evaluate engineering solutions for reducing flood risk in Churchville. Potential solutions may include but are not limited to retrofitting the Victoria Street storm sewer to seal and separate it from local drainage on Victoria Street. This assessment will engage residents, additional regulatory agencies (Province, CVC) and other stakeholders in floodplain management. These assessments typically take upwards of a year to be completed. Only upon completion, and on the expectation that there are meaningful solutions identified, can the City move to implement those improvements.
Development of Ice Management Plan
CVC will develop an Ice Management Plan in accordance with the changes to the Conservation Authorities Act in Bill 23. However, it is not possible to forecast an ice-jam event because the state of the science of river-ice is in its infancy.
Education and Emergency Response
Infrastructure alone cannot protect the people and properties from all extreme rainfall, snowmelt and ice jam events because this neighbourhood is located within the Regulatory floodplain. As such, flood prevention and recovery awareness and education in addition to evacuation and emergency response will continue to be essential components of a flood risk management and reduction plan for Churchville. The City is well prepared for these emergency measures with the leadership of Brampton Fire and Emergency Services (BFES) and the Brampton Emergency Management Office (BEMO) as well as support by Brampton Transit, Public Works, and Region of Peel. The flood forecasting and warning programs run by CVC and Toronto and Region Conservation Authority will support the City in preparing for anticipated events, and the City will work with these agencies to continuously improve joint programs.
