Since phreatic (water-table) aquifers on contaminated sites are often the principal transfer pathway for pollutants, the setting up of a groundwater quality
monitoring network around a site liable to cause pollution is of primary importance for rapid detection and warning.
Experience feedback acquired in groundwater monitoring generally shows that once the primary source of pollution is treated or has dried up, the contaminant
plume, after an initial period of spreading, stabilizes and is, in some cases, slowly diminished by natural attenuation.
Experience feedback also shows that some substances can be degraded into other substances with a different physical nature or into more toxic decomposition
Therefore, when environmental monitoring is implemented, it is recommended that the resulting data be periodically assessed – every four years, for example.
These assessments aim to correctly determine the evolution of any contamination over time and to modify, if needed, the monitoring or protection systems.
Periodic analysis and assessment do not, however, exempt the owner/operator from taking necessary and suitable measures to deal with any anomalies revealed
during a monitoring campaign.
In practice, the situations that might be encountered are highly varied and it is very important that a hydrogeological study be carried out to determine:
•the type of monitoring system to set up (number and location of boreholes, equipment, etc.)
•what pollutants should be monitored
The quality of the monitoring system and the data collected is the site owner's responsibility. It is, therefore, highly recommended that work be subcontracted
to an expert.
Before the work begins, any boring must be declared (DRIRE). Once the monitoring system has been installed, the results of analyses should be sent to the Inspectorate
of Classified Installations.
The Ministry of Ecology and Sustainable Development has prepared specific guidelines for stakeholders and, in particular, for the Inspectorate of Classified
Installations. These Guidelines are called 'Guide méthodologique pour la mise en place et l'utilisation d'un réseau de forages permettant d'évaluer la qualité
de l'eau souterraine au droit ou à proximité d'un site (potentiellement) pollué'.
The French Bureau of Standards, AFNOR, has published recommendations for borehole siting. These guidelines must be adhered to in all situations (AFNOR
FD-X 31-614 October 1999).
Article 65 of the Ministerial Order of February 2, 1998 (modified by the Ministerial Order of August 3, 2001) determines how a groundwater monitoring system
should be implemented (number of boreholes, sampling frequency).
Regulations stipulate obligations concerning the implementation and supervision of monitoring networks. In the event of non-compliance with regulations
or faulty monitoring, the site owner can be ordered to rapidly comply.
New regulations went into effect on February 8, 2007:
•Note of the Ministry of Ecology of February 8, 2007 concerning Contaminated sites and soils - Contaminated site management and remediation procedures
•Circular of the Ministry of Ecology of February 8, 2007 concerning Classified Installations - Prevention of soil contamination - Contaminated site management
•Circular BPSPR/2005-371/LO of the Ministry of Ecology of February 8, 2007 concerning the Closure of Classified Installations - Chain of liability - Defaulting
of responsible parties
•Circular BPSPR/2006-77/LO of the Ministry of Ecology of February 8, 2007 concerning Classified Installations - Application procedure for the detention
of funds as mentioned in Environmental Code no. 514-1
They are based mainly on the Decree of September 21, 1977 concerning the Application of the Law of July 19, 1976 concerning Classified Installations.