Survey of natural attenuation of petroleum hydrocarbon plumes in groundwater in Europe

Report no. 10/18: This report presents a study conducted in Europe to characterize the typical size and plume stability condition for groundwater sites impacted by the petroleum hydrocarbons benzene, toluene, ethyl benzene, xylenes (BTEX), and the fuel oxygenates methyl tert-butyl ether MTBE and ethyl tert-butyl ether (ETBE). This "plumeathon" approach have previously been used in the United States (US) in the 1990s (Newell and Connor, 1998; Kamath et al., 2012; Connor et al., 2014). The study of impacted sites across Europe consisted of an evaluation of 50 sites.

Plume length analysis was conducted for a total of 171 plumes using a primary threshold (10 μg/L for all constituents) and 138 plumes using a secondary threshold (constituent-specific drinking water guideline value). Additionally, plume stability analysis was conducted for benzene and MTBE at 29 sites. Key site characteristics and an evaluation of biodegradation were also tabulated for each site. This study expands the understanding of petroleum plume behaviour to European sites and evaluates site-specific factors that influence this behaviour.