Effects of a temporary HDPE cover on landfill gas emissions: Multiyear evaluation with the static chamber approach at an Italian landfill

According to the European Landfill Directive 1999/31/EC and the related Italian Legislation (‘‘D. Lgs. No. 36/2003”), monitoring and control procedures of landfill gas emissions, migration and external dispersions are clearly requested. These procedures could be particularly interesting in the operational circumstance of implementing a temporary cover, as for instance permitted by the Italian legislation over worked-out landfill sections, awaiting the evaluation of expected waste settlements. A possible quantitative approach for field measurement and consequential evaluation of landfill CO2, CH4 emission rates in pairs consists of the static, non-stationary accumulation chamber technique. At the Italian level, a significant and recent situation of periodical landfill gas emission monitoring is represented by the sanitary landfill for non-hazardous waste of the ‘‘Fano” town district, where monitoring campaigns with the static chamber have been annually conducted during the last 5 years (2005–2009). For the entire multiyear monitoring period, the resulting CO2, CH4 emission rates varied on the whole up to about 13,100 g CO2 m2 d1 and 3800 g CH4 m2 d1, respectively. The elaboration of these landfill gas emission data collected at the ‘‘Fano” case-study site during the monitoring campaigns, presented and discussed in the paper, gives rise to a certain scientific evidence of the possible negative effects derivable from the implementation of a temporary HDPE cover over a worked-out landfill section, notably: the lateral migration and concentration of landfill gas emissions through adjacent, active landfill sections when hydraulically connected; and consequently, the increase of landfill gas flux velocities throughout the reduced overall soil cover surface, giving rise to a flowing through of CH4 emissions without a significant oxidation. Thus, these circumstances are expected to cause a certain increase of the overall GHG emissions from the given landfill site.