Soil testing is complete AFAIK, and the purchase price included a soil remediation budget, so there is no reason why this wouldn't continue after the snow melts.
Of course, given the glacial pace of this development and the lack of any commitment of provincial funding, there is no particular rush. They could probably use a teaspoon and a plastic toy bucket for their "heavy equipment" during the soil removal phase and not impact on the expected construction date for the events centre.