This building is on structural caissons. There will not be any major foundation pits etc.. here. About 6-7 feet deeper to get to the bottom here. They are installing some more dewatering at the site to control the water.
There can't be a whole lot of space between the eastern wall and the subway. Given the way the building meets the street, the lower floor units may be some of the closest to the subway tracks along Yonge, and hence, the possibility of encountering noise issues.