Contaminated Site Monitoring. Integrated real-time supervision for old coking-plant site

The purpose of the Contaminated Site Monitoring (CSM) is to develop a real time management methodology for PAH (Polycyclic Aromatic Hydrocarbons) contaminated aquifer resulting from the coal activity. For the full-scale experimentation, an old coking plant site has been was instrumented (sensors, analysers, data-logger, programmable logic controller, etc.) in June 2000. Its follow-up currently continues with remote supervision, via telecom connection. It is the first time that a CSM is installed for a real time supervision of the natural evolution of PAH pollution in the soil. Because of low propagation velocities, one is generally satisfied with selective investigations, in fact incomplete and non-representative of the real. On the other hand, Environmental Monitoring is widely used for many applications with faster evolution (free water and atmospheric pollution).CSM allows the estimation of the natural biodegradation activity deduced from measurements of biogas in unsaturated area. A strong activity has been observed in hot period (consumption of oxygen and emission of carbon dioxide) and a low one in winter. For the daily rate PAH analysis of aquifer water, a field UV-fluorometer is used. Calibrated every 15 days with naphthalene (the most soluble PAH), the water fluorescence is equivalent to a concentration of naphthalene but a post-treatment of data is necessary in order to correct the drift of the analyser between calibrations. Subsequently the measured and treated data are restituted/exploited on a numerical support carried out by an interconnection between a GIS (Geographic Information System), a Database and a mass transport model (finite element package Feflow^C). The methodology tends to be integrated within a convivial and ergonomic restitution of the whole results on a unique support for decision making support. The polluted site managers can thus visualise any aspect of the information and identify the relevant indicators, which can then be compared with weather data and/or complementary simulation results of diffuse pollution plume at different time scale. (author)