WCW24

During a heavy rainfall in early June 2023 a sinkhole developed over a large diameter storm outfall that threatened nearby homes and the Albert Memorial Bridge. In response, the City activated the Emergency Operations Centre which undertook an emergency project to restore critical storm water service to protect public health and safety. The project presented many challenges including tight timelines and working conditions, working on private property and managing public expectations, the application of innovative construction techniques, and coordinating the efforts of numerous City departments, various levels of government, and public sector partners. This presentation details the efforts taken to stabilize and eventually decommission the outfall while at the same time maintaining storm water service.

Wet weather conditions can bring about challenging conditions for operators of municipal wastewater treatment facilities, especially those facilities that operate with a combined sewer system. Extreme wet weather conditions can bring about flows that exceed the hydraulic capacity of the mainstream treatment process, leading to bypass events that channel the excess water away from the mainstream treatment process. Although dilute, the bypassed water can still carry harmful contaminants that should be reduced prior to discharge. In this presentation, we will review pile cloth filter configurations for wet weather and primary wastewater treatment. Full-scale designs and pilot-scale results will be showcased to demonstrate the technology for these wet weather conditions at municipal wastewater treatment facilities.

Many municipalities experience troubles with drainage crossing pedestrian walkways, creating maintenance and safety concerns, especially during freezing months. The neighborhoods of Donsdale and Carter Crest in Edmonton have experienced issues with water ponding and icy sidewalks in winter due to concrete swales between neighboring backyards collecting flows and draining them directly to sidewalks prior to overflowing to the treed boulevard and road gutter. Stantec was retained to design Absorbent Landscapes or other LID facilities to slow and promote the infiltration of flows conveyed by the concrete swales. This included designing a method of conveying the storm flows below the sidewalk and determining how to install the preferred LID facilities around existing obstacles including mature trees, Canada Post mailboxes, and utilities to minimize disturbance while maximizing the LID storage capacity. This project was completed on behalf of EPCOR Drainage and consisted of the conceptual and detailed design (complete) and support during/post construction (Fall 2023 and expected completion in 2024). Various locations experiencing ponding and ice issues were inspected and solutions were developed including Absorbent Landscapes, Bioretention Gardens, Soil Cells, Permeable Pavement, and grey infrastructure (i.e., catch basins connecting to the existing sewer). Fourteen locations were selected from the concept design to proceed to detailed design and construction. A method for flows to cross the sidewalk from the concrete swale outlet to the Absorbent Landscapes in the boulevard was developed and Stantec coordinated with the City of Edmonton Urban Forestry to construct the facilities around City trees to maximize LID storage while protecting existing tree roots. This presentation will summarize the LID locations and designs, some of the construction challenges and successes, and discuss the applicability of this stormwater management approach to other municipalities.

Cityscapes were initially designed around a purpose and in the case of Winnipeg, it was being a hub for commerce and distribution. While practical for the time it was built, this design neglected natural processes from the beginning and the issues with these oversights will only grow overtime. Concrete environment - while an excellent medium for building foundations - are not what would be considered ideal for stormwater management and as such, require plenty of catch basins, piping and maintenance all to plan ahead for the 100-year flood event. Soil as Infrastructure for Stormwater Retention, Detention and Water Quality will detail an approach using soil cells to allow for an uncompacted soil beneath concrete to be utilized for stormwater management. This approach involves placing support structures underneath concrete where there typically would be a 95 Proctor compacted aggregate used to support the hardscapes in urban landscapes. These structures provide a 90% void space that can be filled with uncompaced soil, allow for utilities to run through them rather than underneath and can hold a firetruck on top of them to allow for the typical loading the compacted medium under concrete may need to endure. The pore space of uncompacted soil allows for stormwater to remain inside the urban environment, acting as an additional layer of flood mitigation where it would normally be considered a hazard. This water can then be utilized for social infrastructure - namely, growing large mature trees - which add to stormwater mitigation through interception in their large canopies, enrich the surrounding environment and create more desirable and prestigious landscapes. These projects include blocks on Broadway and Selkirk Mainstreet, two of the earliest developments in Manitoba's history as a trading hub. With several projects around Manitoba already constructed or currently scheduled, soil cells are already demonstrating effects when it comes to flood mitigation, peak flow reduction and water quality. An area of potential for this technology for this approach would be using it to reduce the size of detention ponds suburban developments. This would allow for new developments to make full use of the land or to substitute in some other feature.

There has been a proliferation of IoT (Internet of Things) devices that are used by municipalities to collect data from Collections Systems, including data from Pump Stations, flow meters, level meters and rain gauges. Integrating this Collection System data with data from numerous other sources is part of the desire by Municipalities to create “Smart” Cities, but that integration has proved to be a daunting task. This presentation will therefore focus on what is available and can be done today, to collect flow/level/rain data, then send it to a cloud-environment where it can be analyzed, which leads to informed decisions, whether on a near-real time basis for operational control, or for more long-term planning by engineers for infrastructure decisions. Topics discussed will include: - Goal of “Smart” Cities, and obstacles to date. - Current monitoring technologies for Flow, Level and Rain meters. - Data collection methods. - Cloud-based software platforms for Data Storage, Analysis and Machine Learning applications. - Sharing data with other software platforms via the use of API's and other transfer methods. - Uses of Collections Systems flow, level and rain data for Operations and for Engineering.

Rossdale and E.L. Smith Water Treatment Plants (WTPs) provide drinking water to the City of Edmonton and surrounding areas and are operated by EPCOR Water Services Inc. (EPCOR). These plants are critical infrastructure identified as vulnerable to overland flood damage from the adjacent North Saskatchewan River. Stantec Consulting Ltd. (Stantec) was commissioned in 2020 to quantify the flood risk further and undertake the preliminary design of flood mitigation measures at both WTP sites. The project is now in the detailed design phase, with construction scheduled to commence in Summer 2024. The design consists of a combination of earthen embankments and cast-in-place concrete floodwalls at each site that meets the design basis of a 1:500-year river flood plus 1.0 m of freeboard. Temporary flood control measures also form part of the design at Rossdale WTP. The flood mitigation infrastructure is designed following the United States Army Corps of Engineers (USACE) standards. Several supporting studies and investigations were required to support the design phase. These included geotechnical soil sampling, non-intrusive geophysical investigation, hydrotechnical analysis of the river, stormwater and civil grading design, underground utility review, waste stream mitigations, landscape architecture design, and regulatory approval planning. The design considers ground conditions, groundwater seepage, underground infrastructure, and floodwater erosion potential. It also adapts to local constraints such as minimizing tree removals, reducing total wall height, and maintaining a naturalized aesthetic to match its river valley setting while still meeting the appropriate design standards. Each WTP site presented unique challenges to the design team. Rossdale WTP is situated centrally within the City of Edmonton and bordered by a residential neighborhood, the river, the historic Rossdale Generating Station, and RE/MAX® Field. Each bordering stakeholder required specific attention to minimize the impacts of the project. Rossdale WTP has been an operational facility since the early 1900s, which presented challenges with existing underground infrastructure and space constraints. E.L. Smith WTP is a more straightforward site than Rossdale WTP; however, a specific challenge was the river's proximity to critical infrastructure. A complex structural design was required to situate a floodwall between existing buildings and the river. The project uses a Construction Management at Risk (CMAR) delivery approach, with Graham Infrastructure LP as the construction contractor. This approach allowed for greater collaboration and enhanced the design process by having regular feedback on constructability, schedule, and cost. The CMAR team also adopted the practice of regularly meeting in a dedicated boardroom at Stantec's office to work closely together and develop a sense of mutual ambition to deliver the project successfully.