150 Slater progress: Piles of fun I

It's time for some updates on the construction at 150 Slater. In previous posts with the 150 Slater label, I documented the demolition of the buildings which used to occupy what is now the 150 Slater site. In the current trio of posts, I'm documenting the installation of the retaining walls, and the removal of the fill.

For reference, here's the site, taken kitty-corner from the intersection of Slater Street and O'Connor Street in Ottawa's Cetnral Business District:

Back in May, before the wooden barriers had been set up, they started driving piles for the retaining walls. Wikipedia has a good graphic here depicting different types of retaining walls.

In the North-East part of the site (the leftmost corner in the above photo, in front of the building), they drew circles with spray-paint using an upended garbage bin for the circle, and a string for a guide:

Into these circles were pounded giant steel cylinders.

Here are some of those cylinders outside the ground, with the machine used to install them behind. The cyclinders are making googly eyes at us:

They installed them outside the former foundations of the Rideau Winter Club (more recently known as Laurier Computer), which I documented in detail in this post. You can still see the little stairs leading up the side. After driving down the cylinders, fill was added, presumably to add support.

Here's another view of that machine. The working end is covered in a tarp:

There are also I-beams on site waiting to be installed. In the foreground of this shot is an old I-beam from the former Rideau Winter Club, which had been levelled a few decades ago. The I-beams in the former building's east wall were left a few feet high to act as fenceposts.

Into the cylinders, I-beam piles were driven into the ground, and the cylinders were removed. Tieback anchors are drilled into the ground behind. (I cover both of these steps as they are performed on different parts of the site in the next two posts, respectively). Besserer Street residents know very well the importance of a well-built retaining wall. Now that the wall is built, work can begin on extracting the soil contained in the newly-formed box.

As fill removal progresses andthe hole becomes deeper, ramps must be fashioned out of the remaining fill, before it, too, is removed:

Once the topsoil is all gone and they hit rock bottom, it's time to blow this joint. As this sign warns: "CAUTION: CONTROLLED BLASTING AHEAD"

Once rock becomes rubble (with the help of explosives), it can be removed, too. In the photo below, we can see how deep the rock is, and how far below they've gone. We can also see the piles continuing below the rock surface. Since they're building a three-storey underground parking garage with 210 spaces, they'll need to blast down by a storey or so.

Stay tuned for the next two posts, including photos of the excavation of the Rideau Winter Club's former foundation.