{"id":18361,"date":"2023-06-18T20:41:51","date_gmt":"2023-06-19T03:41:51","guid":{"rendered":"https:\/\/essential.construction\/news\/caisson-walls-advancing-as-cielo-prepares-for-construction-above-ttc-tunnels\/"},"modified":"2023-06-18T20:41:52","modified_gmt":"2023-06-19T03:41:52","slug":"caisson-walls-advancing-as-cielo-prepares-for-construction-above-ttc-tunnels","status":"publish","type":"post","link":"https:\/\/essential.construction\/news\/caisson-walls-advancing-as-cielo-prepares-for-construction-above-ttc-tunnels\/","title":{"rendered":"Caisson Walls Advancing as Cielo Prepares for Construction Above TTC Tunnels"},"content":{"rendered":"

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Since shoring work began on the site of Cielo Condos<\/a> in late April, the project has moved from careful and calculated heritage conservation work into full-scale construction, and the results are plain to see. The retained portions of the late-19th Century Bloor United Church are now the backdrop for an intensive site preparation effort that will allow the Collecdev<\/a> project to move past the various obstacles that come with construction in established urban areas.\u00a0<\/p>\n

Looking northwest to the retained Bloor United Church on the site of Cielo Condos, image by UT Forum contributor yrt+viva=1system<\/span><\/p>\n

Located on the northwest corner of Huron Street and Bloor Street West in Toronto\u2019s Annex neighbourhood, part of the Cielo site rests directly on top of the tunnels for the TTC\u2019s Line 2 subway. In order to safely excavate the site and construct the project\u2019s four-storey below-grade parking garage, the crew needs to ensure that the surrounding earth maintains its structural properties, and the best way to do that is with a heavy-duty caisson wall. According to Collecdev, this stage will see a total of roughly 260 boreholes created to complete the caisson wall.\u00a0<\/p>\n

Building section drawing shows parking garage next to TTC Tunnels, image courtesy of Collecdev<\/span><\/p>\n

Shoring began in April on the northern limit of the site, while the latest shoring work is concentrated along the western edge of the site now, where drilling is well underway to create the structural caisson wall. In the image below, we can see the string of boreholes drilled by the shoring rig that will soon be filled with a steel pile that reaches a depth of 40 feet, and a whole lot of concrete. The overlapping configuration of the holes is the key to the caisson wall\u2019s load-bearing capabilities, creating a connected wall rather than a row of individual piles<\/p>\n

Looking northeast to the boreholes (left) for new caisson wall, image by UT Forum contributor bhwilkins<\/span><\/p>\n

While shoring continues, the central portion of the site has also been a focal point for preparatory work ahead of the coming excavation. Beneath the church building was a basement with a depth of four metres, creating a substantial grade change in the site that needed to be addressed before shoring could advance. The last month was spent backfilling this basement, a process that saw the hole filled in with loose soil until the entirety of the site enjoyed a consistent and flat grade level.\u00a0<\/p>\n

Looking south to the backfilled site ready for shoring, image courtesy of Collecdev<\/span><\/p>\n

Further north, the project\u2019s other retained heritage element, Pidgeon House, has also seen restoration work over the last few months. Most recently, the crew was excavating the existing basement in order to underpin the building, creating a taller ceiling height below grade. With that process now complete, the large detached house will see the installation of an interior retention system that will limit any significant damage to the building\u2019s interior heritage elements as more active construction work gets underway.\u00a0<\/p>\n

Looking west to the project’s smaller heritage component, the Pidgeon House, image from Apple Maps<\/span><\/p>\n

With backfilling complete and shoring well underway, Collecdev has reported that they expect to see the start of excavation on site by August, which will also include the installation of tie-backs to reinforce the caisson walls as the pit gets deeper. The project is entering the summer with a number of construction milestones on the horizon, and a straight shot to the start of forming work for the highly awarded 29-storey tower designed by KPMB Architects<\/a>.<\/p>\n

UrbanToronto will continue to follow progress on this development, but in the meantime, you can learn more about it from our Database file, linked below. If you’d like, you can join in on the conversation in the associated Project Forum thread or leave a comment in the space provided on this page.<\/p>\n

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UrbanToronto has a research service,\u00a0UrbanToronto Pro<\/a>, that provides comprehensive data on construction projects in the Greater Toronto Area\u2014from proposal through to completion. We also offer\u00a0Instant\u00a0Reports<\/a>, downloadable snapshots based on location, and a daily subscription newsletter,\u00a0New Development Insider<\/a>, that tracks projects from initial application.<\/p>\n<\/div>\n