TRENCHLESS | PROJECT REPORT
expressway that sees more than 100,000 vehicles a day, and which is divided by the city’s LRT. During the design stage, the project team completed
Above: Fence wrap.
a survey of existing manholes within Memorial Drive. Locations matched block profile drawings and the digital base. Due to the trunk’s location in an active driving lane, soft digging was not an option to confirm the location of the connection point without constructing a major detour. A condition assessment inspection was completed utilising a multi-sensory floating platform, and the pipe was established to be in good condition. However, when the unit got to a known bend location in the pipe it kept flipping over, ending the inspection. After many attempts, inspection of the remaining pipe was subsequently abandoned. During construction, when the contractor went to locate the trunk sewer it was not found to be at the identified location but 3m to the south, due to the bend angle and location differing from the record drawings. Fortunately, this newly found location was preferable and allowed for less detour construction.
Importance of monitoring to limit third party claims Construction of the IST took place in dense residential areas and involved crossing critical infrastructure both above and below ground. To reduce exposure to potential claims from adjacent property and infrastructure owners, robust monitoring was in place. The monitoring programme included: 1. Pre- and Post- works inspects of buildings; 2. Noise monitoring; 3. Vibration monitoring; 4. Odour monitoring; and, 5. ettlement monitoring.
Inspections and monitoring prior to construction
Below: Retrieval of MTBM on final drive of project.
established baseline readings and documented existing site conditions. Building inspections were completed by structural engineers from Aecom and the contractors’ third party engineering firm. No building damage was attributed to construction, including to the Artpoint building, where the MTBM passed under the northeast corner.
After the baseline noise monitoring was completed,
monitoring events were conducted during various stages of construction to ensure compliance with local bylaws. Shafts were generally located in parks and greenspaces and commercial areas to minimise impacts on residents. For the Phase Two crossing of Bow River, the launch shaft was located near multiple residences. The contractor installed a concrete block wall to limit noise and also light pollution, resulting in minimal complaints from residents adjacent to the launch shaft. Vibration monitoring units were installed in
residential and commercial structures both beside and over the tunnel alignment. These remote units provided continuous real-time monitoring data. No exceedances were attributed to construction operations. When complaints were received, the data showed that the vibrations were detected but their frequency and intensity were below thresholds to cause damage. Odour monitoring was completed to ensure
emissions from the genset and construction equipment was within contract requirements. Settlement was monitored at building and ground
surface points. For critical utility crossings, a surface point was installed on each side of the utility to allow monitoring on both sides without needing excavation, reducing risk of damaging the utility and avoiding the potential for point loading of the utility.
Community engagement Residents and businesses of Inglewood are very engaged in events and potential impacts within their community. Multiple construction projects were taking place simultaneously during the IST construction - including two bridge replacements, street improvement projects, watermain replacements and the future Green Line LRT enabling projects. To keep residents and business owners informed and complaints minimal, multiple communication strategies were employed, including: 1. Pre-construction open houses; 2. A dedicated website; 3. Monthly newsletters and updates; 4. Frequent construction notices dropped in mailboxes; 5. Emails to affected business owners; and, 6. Fence wrap with details of project objectives and benefits
When the IST project began in 2014, the use of microtunneling was still a relatively new technology in the City of Calgary. Its success has provided valuable lessons for future tunnelling projects in Calgary and beyond.
This paper has been used with permission of the North American Society for Trenchless Technology (NASTT) and edited for space. The full paper can be found at https://
knowledgehub.nastt.org/. Copyright 2026 by NASTT. Original paper was distributed at NASTT 2026 No-Dig Show.
24 | June 2026
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