The 99th Avenue Sanitary Trunk Sewer has been a critical component of the City of Edmonton<\/a>‘s wastewater collection system since the 1970s. The 1.1 kilometre long sanitary trunk sewer is located approximately 30 metres below ground and serves a crucial role in conveying combined sanitary flows from the city’s west end through residential and commercial areas in the West Jasper Place neighbourhood. Over the decades, exposure to hydrogen sulfide gas and natural wear led to significant degradation of the sewer.<\/p>\n\n\n\n
EPCOR Utilities<\/a> manages the City of Edmonton’s wastewater and water systems. Recognizing the urgency of addressing the deteriorating condition of the sewer to prevent potential service disruptions, EPCOR retained Shanghai Construction Group<\/a>, with Associated on their team, to construct Phase 1 of the project.<\/p>\n\n\n\n
With the sewer’s location in a densely populated urban area, it was essential to minimize disruptions to the community and ensure the safety of residents and workers. Significant technical challenges included complex geological conditions, deep tunnel alignments, and proximity to existing infrastructure and environmentally sensitive areas. EPCOR and project partners devoted considerable time and resources to developing a comprehensive plan that would address the project’s technical, logistical, and community-related challenges. To minimize community impact, the project was delivered in two stages spanning three years and incorporated proactive community engagement.<\/p>\n\n\n\n
One of the most significant challenges of the project was selecting an appropriate alignment for the bypass sewer. We conducted extensive geotechnical investigations to understand the soil conditions along the proposed alignments. This involved drilling numerous boreholes and conducting soil tests to assess the composition and stability of the ground at various depths.<\/p>\n\n\n\n
This assessment showed a number of challenging conditions for the tunnelling to traverse. This includes rafted bedrock, sand seams, with boulder fields all within the dense clay till.<\/p>\n\n\n\n
Employing advanced construction techniques were critical to addressing technical challenges and the success of the project. One key decision was selecting microtunneling as the preferred construction methodology. Microtunneling allowed for the installation of underground pipelines with minimal surface disruption. This was particularly important for this project, given the depth of the tunnel and the proximity to existing infrastructure. Significant secant structures were constructed in order to reach the depth needed for the installations.<\/p>\n\n\n\n
A significant portion of the project was located within the North Saskatchewan River Valley, one of Edmonton\u2019s most environmentally sensitive areas. The river valley is not only a vital ecological corridor, but also a cherished natural asset, providing habitat for wildlife, as well as recreational spaces. The project team implemented rigorous environmental protection measures. Construction activities were carefully planned and executed to minimize disruption to the natural environment, particularly within the river valley. Special attention was given to preserving the integrity of the existing landscape, and the overall ecological balance of the area.<\/p>\n\n\n\n
North American Society for Trenchless Technology’s 2024 Project of the Year Award Winner<\/a><\/strong><\/em><\/p>\n\n\n\n
Associated’s team was led by Jason Lueke<\/a><\/strong> and included Chris Lamont, Sam Saunders, Ryan Krausher, Dusanka Stevanovic, Caitlin Lou, <\/strong>and Greg Walker<\/strong>.<\/p>\n\n\n\n