The job was awarded to Boskalis bv in October 2000. The smell of the naphthalene, benzene and toluene was so serious that the complete removal of the layer of sludge ultimately proved to be the only possible option. Because the gasometers were located less than 50 m away from houses and because of the presence of a number of trees with ecological value, a separate project plan was written for this part of the work. Boskalis Dolman bv was called in for the development and implementation of the plan. The dredged material was stored in the second gasometer, which was enclosed in a special tent fitted out with a ventilation and air conditioning system. A spray system was used to minimize odor problems during dredging in the first holder and a sludge separation plant was used to clean the rinsing water. The work complied with the strictest Dutch safety standards for soil remediation work. The extensive safety measures and monitoring made it possible to complete the work successfully and without incidents.