English 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.
