Seventy acres seems to stick in my head. The water park takes up a fraction of this acreage. This doesn't include the parking lot, which they share with the Coors Ampitheater. This causes some logistic problems as they have to close the park and clear the parking lot at a predetermined time before a concert is held.
As far as seeing pig iron on the property, your guess is as good as mine. Rumours flew about this shortly after CF bought it from the city. I am not aware of any site use stipulations that went with the property.