Influence of Soil Air Permeability Change on Soil Vapour Extraction Systems Design |
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| Authors: | Otmane Boudouch Esrael Daoud Kacem Mariem Belkacem Benadda |
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| Institution: | 1. Laboratoire de Génie Civil et d'Ingénierie Environnementale, Université de Lyon, INSA de Lyon, Villeurbanne, France;2. Laboratoire de Tribologie et Dynamique des Systèmes, Saint‐Etienne, France |
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| Abstract: | Soil air permeability plays a decisive role in the effectiveness of soil vapour extraction (SVE) for the removal of volatile organic contaminants (VOCs) from soil. The objective of this work is to study the change of the soil air permeability during continuous venting and removal of contaminant from a polluted soil. SVE pilot experiments were conducted to investigate the interaction of soil air permeability with total liquids saturation. Oppositely to previous studies, air permeability was measured by fitting pressure data measured in a 3D laboratory venting pilot to an analytical airflow solution. The experimental correlation was compared with two different correlations published previously. A difference was observed between measured and calculated air relative air permeabilities especially for low water saturation degrees. The importance of the correct estimate of relative permeability was then illustrated by comparing vacuums and streamlines calculated using measured permeability and permeability values estimated with the two correlations tested here. Results show that an inappropriate assessment of relative permeability may engender significant errors in designing an SVE system. The second part of this work reports on the influence of air permeability change on the prediction capability of an SVE mathematical model. A significant difference between simulated breakthrough curves, estimated using firstly the relationship established experimentally and secondly the two other correlations, was observed. These results lead us to say that inadequate characterization of the air permeability change may generate significant errors in removal rate and closure time estimates. |
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| Keywords: | Closure time Saturation degree Soil air permeability Soil vapour extraction |
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