Proposed changes for post-closure monitoring of Etueffont landfill (France) from a 9-year survey

Highlights: • First nine years assessment of the Etueffont landfill's post-closure phase • Physico-chemistry of water and piezometers along with bacteria counts • The Decree of 9 September 1997 shows the flaws as to environmental monitoring. • Proposed monitoring guideline for Etueffont landfill until December 31, 2031 -- Abstract: Environmental monitoring must be continued following landfill closure for at least 30 years according French Waste Disposal Law. The goal of this investigation was to verify whether measures taken with respect to surveillance and control of leachates, surface and ground water originated from closed landfill site in France are sufficient to ensure reliable long-term environmental monitoring. This study is based on the first nine years of the Etueffont landfill's post-closure phase, from 2002 to 2010. In 2007, the site's piezometric network has 17 piezometers. Four supplementary sampling points were also added in up- and downstream of Gros Près and Mont Bonnet Brooks. No raw leachate was discharged directly into the natural environment. Piezometric monitoring has been undertaken monthly. Groundwater and effluent discharges were sampled twice per year, in January and July, while surface water was sampled three times annually. By taking into account all of the monitoring parameters imposed by the Decree of 9 September 1997 amended, the recorded values were all lower than the strictest standards (non-applicable) at the end of monitoring (2005–2010). The discharge is therefore of a much higher quality than required. Several parameters were undetected in the surface waters since their levels were below analytical detection limits. The average purification efficiency observed between upstream (the source) and downstream (MB Brook), observed to be between 72 and 91%, shows just how well the receiving environment can purify contaminated waters by natural attenuation. The groundwater present throughout the monitoring period to be at concentrations below the standards for the following parameters: Total phosphorus, Total nitrogen, Escherichia coli (E. coli), As, Zn, Cd and Cr. In contrast, some excesses are occasionally observed for the organic parameters (TOC, COD and BOD). Thus, this study shows the flaws inherent in the environmental monitoring program imposed by the Decree of 9 September 1997. Consequently, the program has indeed been adapted to the monitoring of effluent discharges and surface water quality since the decree does set quality standards.