The peat areas around Amsterdam became lower and lower from the 11th century onwards. This increased the risk of flooding from the Zuiderzee. The “All Saints Flood” of 1170 was the reason for constructing the Diemer Sea Dike. In the centuries that followed, the dike often breached. The dyke was reinforced time and again. In 1916, the Diemerzeedijk broke at Fort Diemerdam. This was the last flood. In 1932 the Afsluitdijk was built. So from then on, the Diemerzeedijk no longer holds back Zuiderzee water. The Diemerzeedijk now stops water from the Markermeer.
During the last century, the municipality of Amsterdam used the site as a dumping ground for years. Next to dumping, the municipality also burned household and chemical waste there. With the arrival of IJburg at the end of the last century, a clean-up plan was designed. It was decided to contain the contaminated soil and groundwater (IBC: Isolate, Maintain and Control). A “box” was made two and a half kilometres long and one hundred and thirty metres wide with a depth of 26 metres. With a screen wall on the sides and an already existing thick clay layer at the bottom only the top side was exposed. It was decided to seal off the top cover with a Trisoplast layer, topped with an eighty-centimetre thick ancillary (soil) layer. The groundwater level inside the “box” is kept lower than that in the surrounding area, preventing polluted water from leaking out.
A new city park, the Diemerpark, has risen on the contained, contaminated soil. The park consists of grasses, herbs, small trees and shrubs. A recreation and sports area has also been created. It is intensively used by the residents of IJburg.