It was planned to finish the flood barrier in 1985 but soon they realized that this was impossible so it was moved to 1986. The columns for the dam were prefabricated near the village Vrouwenpolder for this place was not influenced by tides. Totally 65 columns had to be made. Two of them were extra, for the dam only 63 were needed. Between these columns 62 slides ensured the protection when needed. When the gates were open 75% of the tidal movements still was present in the Oosterschelde. When these slides were lowered down no water could go in or out. A policy when to close the flood barrier was made: closing only by extreme storm or high tide and environmental disasters on the North Sea to prevent spoiled oil floating in the Oosterschelde. The time the dam is closed is critical: when it is too long many marine species can die and the constant water pressure can damage the dikes surrounding the Oosterschelde. There were many discussions by the Government about the Oosterschelde flood barrier. The different delegations couldn’t make an agreement about the costs of this project. Finally in 1976 each party agreed with a plan of a barrier with gates with a total of 115000 m2. All this will cost 2 billion HFL. Although many problems could be foreseen they decided to cope with them when they appear. And as predicted after a few years the costs increased with 6%.