Protecting Edmonton's Water Treatment Plants from flooding

Developing barriers to protect equipment and water reservoirs

To protect the Rossdale Treatment Plant in a situation where the North Saskatchewan River overtops its banks, our engineering studies have shown that permanent flood barriers are needed in key locations around the facility. Once constructed, these barriers will limit potential damage to critical equipment and drinking water reservoirs, and ensure that we can resume producing clean drinking water as quickly as possible after a flood.

We compiled and assessed all of the perspectives, suggestions, and comments received during community engagement. The following map shows the a combination of grass-covered embankments and flood walls that will be built around Rossdale to meet technical requirements, reduce the impacts to vegetation and minimize the cost to rate payers.

Two types of flood barriers can be used to protect the water treatment plant in the case of a major flood.

With either type of flood barrier (wall or grass-covered embankment) buffer zones are in place that restrict the type of vegetation that can be replanted. The buffer zone is about 5m from the wall or end of the embankment slope. This is to maintain the structural integrity of the barrier. Sod or naturalized grasses are the only option for replanting here. Roots from large vegetation can encourage burrowing animals.

Developing barriers to protect equipment and water reservoirs 

To protect the E.L. Smith Water Treatment Plant in a situation where the North Saskatchewan River overtops its banks, our engineering studies have shown that permanent flood barriers are needed in key locations around the facility. Once constructed, these barriers will limit potential damage to critical equipment and drinking water reservoirs, and ensure that we can resume producing clean drinking water as quickly as possible after a flood.

We have compiled and assessed all of the perspectives, suggestions, and comments received during community engagement. The following map shows the a combination of grass-covered embankments and flood walls that will be built around E.L. Smith to meet technical requirements, reduce the impacts to vegetation and minimize the cost to rate payers.

Two types of flood barriers can be used to protect the water treatment plant in the case of a major flood.

With either type of flood barrier (wall or grass-covered embankment) buffer zones are in place that restrict the type of vegetation that can be replanted. The buffer zone is about 5m from the wall or end of the embankment slope. This is to maintain the structural integrity of the barrier. Sod or naturalized grasses are the only option for replanting here. Roots from large vegetation can encourage burrowing animals.

Some trees will be removed during construction. After construction, a maintenance zone where some types of vegetation are restricted will be established to make sure the flood barriers work properly. While we worked to minimize the impact of the barriers, regrettably, a total of 557 trees will be removed between both plant sites. However, we have plans in place to revegetate more area than we remove once construction is completed.

The following illustration gives you an estimate of the trees that will be removed.

The maps below show two states of vegetation

The light green space around the barriers shows the “barrier maintenance zone” where vegetation will be removed to preserve structural integrity. This zone is about 4.6 metres wide on either side of the barrier.

The dark green space shows areas that are being considered for naturalization. This could include wildflower/pollinator gardens, planting more trees, and developing undergrowth around already treed areas.

Rossdale Water Treatment Plant conceptual map

E.L. Smith Water Treatment Plant conceptual map

The maps show the expected impact from the flood mitigation project and preliminary areas that are being considered for naturalization. We will plant pockets of vegetation in the areas marked on the map where possible, where human connection points, infrastructure and maintained areas allow.

We will work with the City about how and where to add trees and vegetation on city land outside our fencelines.

As part of developing the Vegetation Management Plan, EPCOR asked interested Indigenous Nations to form a Traditional Ecological Knowledge working group to provide meaningful input to vegetation management at the two Water Treatment Plant sites.

In the first half of 2023, EPCOR held several meetings to walk the sites, discuss shared values and naturalization strategies, and gather feedback to ensure these lands were cared for. We are now incorporating this advice into our vegetation management plan, which will target a return to a natural Prairie Parkland ecoregion as appropriate. There is also a strong desire for harvestable berries and ceremonial sites for Indigenous teachings.

All together, we reached out to more than 30 Nations to engage on vegetation and construction, and have held four pipe ceremonies at the Rossdale Water Treatment Plant so far to help ensure we are moving forward in a good way.

Supporting urban Indigenous ceremony

We will provide some of the removed trees as part of this project to kihcihkaw askî for ceremonial and traditional uses. kihcihkaw askî provides a natural setting in Edmonton for Indigenous Peoples, groups, and communities to host ceremonies, sweat lodges and facilitate intergenerational learning.​​​​​​​​​​​​​​

As part of our plan to protect our Water Treatment Plants during a major flood event, we are working to increase the protection of critical assets on site or
relocate them.

We're working on a comprehensive risk assessment and a review of flooding pathways to ensure equipment that is critical to the operation of the water treatment plant is protected in case of a major flooding event. This work may involve installing barriers, moving equipment up higher, or making equipment submersible. This work will all take place within existing buildings on the site and within our fence line.

This work is currently underway and we expect it to be completed in the fall of 2025.

What does "critical" mean?

Some critical assets at the Rossdale site include transformers that supply power to the water treatment plant, underground drinking water storage reservoirs, and underground tanks that contain additives used in the water treatment process. Others include pumps, sensors and valves that could fail if they were to get wet. See the water treatment process in action.

Another part of our plan to protect our Water Treatment Plants during a major flood event includes preventing river water from backing up into the water treatment plant through drainage pipes that discharge to the river.

Our Water Treatment Plants have piping systems that collect rainwater and process water to be returned to the river. Today, those are open outfalls that could allow river water to flow in the opposite direction during a flood. If that were to happen, we would see surcharging from manholes that could allow water to reach sensitive equipment. We would also see untreated river water backing up into the treatment plant, contaminating the process with untreated water and the harmful microorganisms we are trying to remove.

We plan to install valves in the piping systems that we can close in the event of an elevated river level to prevent this from happening.
This work is currently planned to take place within existing buildings on the site and within our fence line.

The planning for this work is currently underway and we expect all to be completed in the fall of 2025.

Did you know?

Edmonton has two water treatment plants, and has been providing water to Edmontonians since 1903. Water from the North Saskatchewan River is treated, tested and stored on-site in reservoirs until is needed. Safe, clean drinking water is then pumped out through the transmission/distribution system to homes and businesses throughout the city and the surrounding areas.

• 2018 - Stormwater Integrated Resource Plan presented to Edmonton City Council
• 2020-2021 - Shared outcomes created with the community
• 2021 - WTP Flood Phase 1 community and Indigenous engagement
• Early to Mid 2022 - WTP Flood Phase 2 community and Indigenous enagagement
• Fall 2022 - Phase 3 community and Indigenous engagement (We are here)
• Late 2022/Early 2023 - Present WTP flood barriers to Edmonton City Council
• 2023 - Final design selection process for WTP flood barriers
• 2024-2027 - Construction at the WTP

We are committed to working with community members throughout the planning and construction of these necessary flood barriers, and community and Indigenous engagement is ongoing. 

• Following the Shared Outcomes development, EPCOR undertook the first two phases of community engagement between May 2021 and June 2022.
• ​Phase 3 is planned for the Fall of 2022 to reflect back the input received. 
• Two more engagement phases are planned to follow, one in 2023 to roll out the detailed designs prior to construction, and one through 2024-2027 to keep communities up to date on construction progress. 

As a precursor to the Edmonton Water Treatment Plant (WTP) Flood Mitigation Project, EPCOR invited community members, Indigenous communities and First Nations, special interest groups, residents, recreational user groups, community league representatives and individuals who have interest in the WTPs to help es​tablish five shared outcome statements. These shared outcomes will guide our work at the Rossdale and E.L. Smith Water Treatment Plants moving forward.

Following this shared outcome work, we conducted two phases of the community engagement process​ to the REFINE level in our public engagement framework, by seeking community members’ input to help us improve the quality of the project design.

• We first sought to understand how community members use the spaces around the water treatment plants, and what they value most in terms of design. 
• We talked with local community members, rights-holders and Indigenous Nations and communities, sharing information about permanent flood barriers planned for installation around the water treatment plants.
• We collected feedback about how the barriers will be experienced by those who live, work and recreate in the areas around the facility. 
• We heard from a number of community members who shared their perspectives on which design considerations are important for EPCOR to consider while building flood barriers. 

We conducted community engagement using a variety of techniques, including online and in-person workshops, one-on-one meetings, and regular project communications. ​

Following the City’s review process, we will work with Indigenous Nations and local communities to add art and interpretive installations for people to interact with and enjoy, based on their feedback. Watch for more information coming soon about how you can get involved in this engagement process.

We expect to begin construction on the flood barriers in 2024. Although there are key decision points along the way, we will continue to engage with community members and Indigenous Nations throughout the project.

The considerations for flood barriers are different at each water treatment plant.

Addressing community concerns

During conversations with the Rossdale community, we heard a number of questions relating to the impact of the project, and EPCOR’s role as a neighbour in the community. To summarize these concerns: 

1. ​​What is EPCOR doing to support flood protection for local communities as a whole, such as through the Stormwater Integrated Resource Plan? 

2. How is EPCOR ensuring that the proposed flood barriers will not adversely affect nearby homes in the event of a major flood? 

3. What are the approval processes for the funding and project overall, and how can community members get involved in those processes?

A key commitment of our plans to protect the Rossdale Water Treatment Plant is that the flood barriers will not worsen flooding in the surrounding neighbourhood or negatively impact nearby homes. EPCOR relies on hydraulic modelling from the provincial government, which is based on work by the United States Army Corps of Engineers. The modelling, as confirmed by a third-party consultant, shows that there would be no change in the water level across the flood plain around Rossdale due to the treatment plant flood barriers.

EPCOR also has programs in place to help mitigate other impacts of both rainfall and river-related flooding. 

• ​Stormwater Integrated Resource Plan, a 20-year, $1.6-billion plan that includes a variety of actions to slow, move, secure, predict and respond to flooding in Edmonton neighbourhoods.
• Homeowner Flood Prevention Program, which includes free home inspections and a backwater valve subsidy is also available to eligible properties.

EPCOR plans to review the project plan with City Council in late 2022/early 2023. 

Flood barrier design

A combination of grass-covered embankments and flood walls will be built around the Rossdale Water Treatment Plant to meet technical requirements, reduce the impacts to vegetation and minimize the cost to rate payers. 

At two locations facing east, we asked participants what kind of flood barrier they preferred. The three primary options explored were a grass-covered embankment, a flood wall, or a combination of the two. Responses were nearly evenly distributed between these options. 

However, the community input did provide insights into how they want the barriers to look and feel. These design considerations, which we will take forward to detailed design, include: 

• Create space for recreation and transportation
• Blend into existing surroundings
• Consider how to discourage vandalism
• Improve “institutional” look/feel of the WTP
• Celebrate the history of the area
• Add amenities that support recreation and community gathering
• Align with City, EPCOR, and Community priorities

A combination of grass-covered embankments and flood walls will be built around E.L. Smith to meet technical requirements, reduce the impacts to vegetation and minimize the cost to rate payers. There was a clear preference for maintaining the natural state of the area as much as possible, and participants also noted opportunities for sharing education and history with visitors. 

The following are key insights from community members’ feedback: 

• Prioritize maintaining and enhancing existing environment
• Support existing recreational use through minimal amenities
• Include educational features that include Indigenous representation
• Align with City, EPCOR, and Community priorities

We recognize the archaeological and historical significance of the sites of the plants; the importance of these areas in fostering communities predates the City of Edmonton itself. It was important to EPCOR that we seek out, hear, and include the perspectives of the 32 Indigenous Nations and communities with an interest in these lands and will continue these conversations throughout this project.

Feedback and responses were gathered from Indigenous Nation and community representatives during in-person walking tours, virtual information sharing and guidance-seeking workshops, monitoring activities and one-on-one conversations.

Did you know? 

EPCOR is aligning with the principles of OCAP® (Ownership, Control, Access, Possession) for this work, and continues to work with participating Knowledge Keepers and Indigenous Nations and communities to ensure protocols are in place for appropriate management of the Indigenous knowledge that is shared.​

The following themes emerged through Indigenous engagement: 

• ​The importance of Water
• Consideration for the Environment, tree removal, replanting
• Allow for interaction with the land, maintain harvesting opportunities
• The many histories and stories of the areas 
• The importance of Treaty
  

As we move forward, we will continue to work with Nations to address these key themes. EPCOR will prioritize reconciliation: working collaboratively with Indigenous Peoples to reconnect with their historic lands, by creating opportunities for monitoring archeological work, shared learning, conducting ceremony, and traditional plant harvesting. 

In terms of specific feedback on the barriers, following is a summary of what we heard: 

• Diverse perspectives on walls, berms and wall/berm combination
• Stone was the preferred treatment, as brick can be a reminder of residential schools
• Storytelling plaques and artwork to adorn or be displayed along walls
• Amenities including plaques and benches that speak to Treaty and Stories
• Recognition of the use of the land by many diverse peoples throughout history
• Emphasis on the importance of Ceremony before and throughout the project
• Continuous Indigenous Monitoring of ground disturbances
• Employment opportunities for Indigenous people