The new building was built to LE E D standard s.
ing were f scaffold cement. o s e ri to pla Four s shotcrete e th r fo used
forming), and the fourth wall with structural shotcrete by Torrent Shotcrete Structures. As the walls were to incorporate the drain mat system around their perimeter, tanking the four walls would be critical. The system needed to be completely sealed, which was especially difficult where the shotcrete wall met the cast-in-place walls.
To assist with handling the ground water flowing below the slab, an extensive system of perforated drainage pipes was installed beneath the slab and around the perimeter of the building, called a drain mat system. The system was connected to a sump which The wall installed with shotcrete involved had a three unit pump station connecting to a number of challenges. To begin with, the the city’s storm sewer system. wall was much larger than normal at 36 m x 9 m (120 ft. X 30 ft.), needing four stories The project’s most critical construction of scaffolding for the shotcrete placement. factor was the absolute requirement for the Additionally, as the structure was high-voltage machinery within the below reinforced to seismic standards (leaving grade areas to be kept completely dry. The it essentially ‘bomb-proof’), the heavily station cannot be shut down to repair leaks, congested rebar made for more difficult so the waterproofing solution had to be placement to ensure no water retaining permanent as there would be zero tolerance voids were created by the extra obstacles. for leaks and moisture. Commonly used sheet membranes are There were many factors to consider when known to be difficult to apply where selecting a concrete waterproofing solution cast-in-place meets shotcrete. As a sheet that the project team could be confident in. membrane had originally been specified for One concern was the fact that one of the the project, the team began to search for walls could not be placed using two-sided a more compatible waterproofing solution forming, therefore three walls would be that would provide assurance that the built using cast-in-place (with two-sided building would remain watertight. krystol® volume 17 | issue 1
After much research and consultation, the construction team selected Kryton’s Krystol Internal Membrane (KIM) Concrete Waterproofing admixture to waterproof the below grade areas, and the Krystol Waterstop System to fully tank the joints and seams against water penetration. These areas would include the 1.5 m (5 ft.) thick raft slab and all below grade walls. The Kryton Waterproofing System was used to support an externally applied sheet membrane, as the sheet membrane could not be trusted as the only waterproofing solution for this high risk project. Jeff Bowman, Kryton’s Technical Manager, provided comprehensive training on the application of waterstop system, and made multiple site support visits. Construction is expected to be completed early 2014, and is part of an ambitious portfolio of hydroelectric and transmission projects completed by BC Hydro, to meet the projected growing energy needs of the province.
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