When I chatted with Patricia Mariash last summer she joked they had drilled more holes at the Roundhouse site than there were oil wells in Alberta. I think they have a pretty good idea of the amount of contamination.
During the spring street fair I chatted with one of the other Roundhouse folks. He mentioned that they were considering moving the density to put a tall building at the spot closest to Spinnakers. He said the idea was to give a "lighthouse" effect to people entering the harbour.