The ground for the London Olympics site is so polluted with oil, arsenic and other contaminants that giant soil 'washing machines' have been brought in to process the soil in order that construction may start.
The two square miles between Stratford and Hackney Wick are now being cleaned, before construction starts in two months.
This has the "honour" of being Europe's largest land cleansing operation, it will remove over a century's worth of contamination.
Over 1.5 million cubic metres of soil has to be processed.
The Olympics Delivery authority's Utilities director, Simon Wright, said:
"It's enough to fill 600 Olympic sized swimming pools."