The 'Kuil van Keet' Natural Attenuation Project

Based on earlier findings (1996) a study was undertaken to quantify the amount of natural attenuation in the saturated zone and unsaturated zone with special interest the capillary fringe including the smear zone.  For this underground laboratory was installed in a 1.2 m (4 ft.) diameter steel tube reaching 6 m. (24 ft.) Below the surface. 3 floors were constructed from which measurements could be made with sensors through holes in the tube wall. The sensors were connected to analytical instruments (GC-TCD, UV-Vis) and data processing and logging instruments in the container seen in the background. This way continuous recording was possible of: Air movements (3D) in the unsaturated zone (down to 1 mm/hr); concentration of gasses (O2, CO2, N2O, CH4, H2S and HC vapors); in the data processing unit these two were combined as flux of the individual gasses; The system records also the groundwater flow direction (2D) using the G&H groundwater vector-sensor and variations in depth, NO3 concentration in capillary fringe to measure diffusive movement, meteorological conditions: wind speed and direction, sunshine intensity, air temperature and humidity, rainfall and evapotranspiration. Most data were recorded every 15 minutes for a 6-month period. For results ask for full report (e-mail) or see under articles / publications at poster presented at Battelle's first contaminated sediments conference held in Venice Italy 10-2001.