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Subterranean Solutions

It’s amazing what lurks beneath the surface of our fair cities…

In Tsawwassen, BC, a series of 4 large, subterranean water reservoirs lie beneath the public tennis courts at Pebble Hill Park. Our client, The Bennett Group, was hired by the engineering team at Metro Vancouver to provide seismic and structural upgrading to the first of these four reservoirs.

Think of a large underground concrete swimming pool -  about half the size of a football field - with a lid on it (the tennis courts) and you get a visual sense of what they look like.

The interior walls of the tanks were deemed to be structurally inadequate after years of continued usage and as a result, a new structural concrete wall was designed to be placed against the existing walls. It was a job tailor-made for the advantages of air-placed structural concrete. In other words, shotcrete!

While the south-facing wall of the 4 new walls required only a straight, vertical wall to be shot, the other three new walls involved 3 phases to the upgrading; a vertical wall from the bottom of the internal walkway ledge the travels all around the reservoir interior, followed by a 2:1 corbel and finally, a 12” deep upper beam to placed all around on top of the corbel, flush with the existing concrete ceiling above.

The original engineering design called for the vertical faces of these three walls to be shot, while the corbel and top beam upgrading were to be accomplished using a cast-in-place application. Due to the restrictive shooting environment and the existing ceiling, this would have made for a difficult, time-consuming and expensive undertaking.

Torrent provided the Bennett Group and Metro Vancouver team with an alternative option.

Torrent’s Operations team was able to show Bennett Group Project Superintendent, Jay Vernon and Bennett Project Manager, Scott Reed a more efficient way to construct the walls. By altering the corbel design and reconfiguring the shoot sequence, the wall, corbel and upper beam could all become shootable without the need for any forming. The entire job could be completed with shotcrete alone in a fraction of the originally planned for.

In addition, by taking advantage of scaffolding already in place for use by other subcontractors, Torrent was able to construct an extended shooting platform which made the nozzling more efficient and the challenging task of proper concrete consolidation in a high-density rebar configuration much less daunting.

Our value-engineered design and construction methodology alterations were accepted by both the Bennett Group and the engineering team at Metro Vancouver and Torrent successfully shot all three components in the same day, saving the client considerable time and money.

The Pebble Hill Park Reservoir is a great example of how Torrent’s experience and expertise paved the way for substantial project acceleration and tangible savings to both the general contractor and the project owner.

Torrent Shotcrete. More wall. Every day.

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