The Pemberton slide was actually bigger then the Frank slde (which I also have also been through). The newest estimates on the slide near Pemberton is that it was 40 million cubic metres in total.
This link describes more in detail. The
BC Place stadium they refer to is a covered 60,000,00 seat soft dome stadium in downtown Vancouver Canada that is currently undergoing a refit to a retractable roof. if any of you watched the opening/closing 2010 Winter Olympic ceremonies, it will give you a sense of how big the inside of the stadium is.
The Hope Slide is considered the biggest Canadian slide in modern times (1965). The town of Hope is about 90 miles east of Vancouver and the slide area is a few miles up from there on Highway 3 East. I have some photos somewhere of the debris and boulder field and will post them if I can find them.
Some very good photos of the Pemberton Slide area can be
seen here and here. The top of the peaks is at about 8500'