Abstract

In this study on three construction sites in the Rijnmond area (around the Rotterdam harbour) which were elevated with dredged sediment from the New Waterway area, the radium level of the soil has been determined and data on the groundwater level and the thickness of the (natural) soil horizon have been collected. On all the sites the average radium level was found to be above 60 Bq/kg. The calculated radium levels ranged from 54-143 Bq/kg for Spaland to 90-96 Bq/kg for Stormpolder-Noord. There is no clear explanation for the large variation in the results. For the Spaland site the available data show that the groundwater level in the built-up section remains constantly above the dredged sediment-soil horizon interface. For the Stormpolder-Noord (built-up section) site the groundwater level is found below the soil horizon. Data collected in 1990-1992 show that for part of the year the groundwater level for the site in Spijkenisse remains below the soil horizon-dredged sediment interface.