The City’s storm water management system moves rainwater away from communities and into the South Saskatchewan River and local creeks.
Storm system design
The system includes a network of:
- over 300 km of storm mains/catch basin leads
- nearly 11,000 catch basins/manholes
- 23 storm ponds
- almost 300 outlets/outfalls
- concrete swales
- curb and gutter pathway to catch basins
- trap lows
Trap lows
A key component of the storm system is our road network that, in some areas, is designed to store water on the surface of the street until the storm pipes are able to drain the water away. This is called a trap low. For homes near trap lows, rainwater may accumulate on the road nearby, up to and sometimes including the driveway and a portion of the lawn. This is normal for areas with a trap low. The water should completely drain within 24 hours once the rain stops.
Challenges during severe weather events
Our system effectively manages the vast majority of rain events experienced during the year. However, the system has a limited capacity and may be overwhelmed during severe storms.
High volume in short duration
Over recent years, Medicine Hat has experienced some very severe events where a significant volume of water was deposited over a relatively short period of time. During these events, the underground pipes fill to capacity and rainwater pools on the roads at the trapped lows as it is intended.
Blocked gutters and catch basins
In addition to the rain, severe events may also bring high winds and hail that create debris on our roads (branches and leaves). The hail and debris may impede the flow of water in the gutters as well as block the catch basins. When this happens, the effectiveness of the storm system is severely reduced, which results in increased road pooling/flooding.
Unpredictable weather
Typically, severe storm events occur with short notice and in relatively confined areas (i.e. some areas will experience heavy rainfall but other nearby areas may experience significantly less rain). Predicting weather patterns and exactly where and when a severe storm event will occur is a major challenge.
Our crews continually monitor the storm water system and apply proactive measures to ensure the system is working at full capacity.
Storm system maintenance and rehabilitation
The City completes ongoing maintenance such as catch basin cleaning and pipe flushing, as well as repairs and rehabilitates damaged infrastructure as part of our annual Storm Rehabilitation Program.
Street sweeping
Our spring street sweeping program and ongoing sweeping activities helps keep road debris to a minimum.
Pumping
With enough notice, we respond with our best effort and available resources to deploy surface pumps to help move pooling surface water from low lying areas to other areas where the water can be stored or released.
Our storm system carries rainwater to the South Saskatchewan River and local creeks. To protect these valuable natural resources it is important to keep trash and chemical pollutants such as detergents, pesticides, paints, motor oil, etc. from entering the storm drains. Polluted water is harmful to fish, other wildlife, and humans.
The City continues to look for new and innovative ways to address severe weather situations. This includes investigating the effectiveness of temporary holding ponds where storm water may be pumped and stored until a time when it can be released into the system.
As part of the annual Storm Rehabilitation Program, we consider increasing the capacity of the pipes and catch basins when existing infrastructure has reached the end of its useful life. As part of our Road Infrastructure Rehabilitation Program, we repair, rehabilitate and/or replace road infrastructure including curb and gutter and road camber (arch in road) to improve drainage flows along the roads where possible.
Storm systems are built to certain standards which have evolved over time. As a result, many of Medicine Hat's older neighbourhoods have systems built to much different standards than what would be built today. Older neighbourhoods may have smaller capacity pipes and may be more prone to water accumulating on the roads or even entering private property.
Neighbourhood development standards have also evolved over time where today’s structures are built to higher elevations that significantly reduce the risk of water entering the buildings. This also suggests that older areas may be more prone to taking on water.
Homeowners can take proactive measures to help protect their properties from the effects of severe storm events.
- Raise landscaping and grade away from buildings
- Maximize “soft” landscaping on properties (lawns and gardens) to help with water infiltration, thus reducing drainage onto the road
- Install on-site sumps and pump out when necessary
- Waterproof building doors and windows using commercially available products such as watertight window wells, sandbags and water-activated flood barriers
- Install rain barrels to capture some of the roof drainage
If you notice excessive debris on the road or plugged catch basins or surface grates, please call us at 403-529-8100.
