Determining groundwater MTBE sources using reverse particle tracking: Two case studies

Abstract

ABSTRACTIn two case studies, low levels of methyl tert-butyl ether (MTBE) were alleged to have entered residential wells from neighboring gas stations. In the first case, reverse particle tracking established that only 8 of 32 plaintiffs' residential wells could have been impacted by MTBE emanating from the gas station as alleged. Particle tracking correctly attributed the high levels of MTBE in six wells southwest (down-gradient) of the gas station to have originated from the gas station. Two other wells were identified as potential future targets. Particle tracks indicated that the remaining 24 wells received water from generally further north, and it is unlikely that the low level of MTBE detected in these 24 wells originated from the gas station. In the second case, there was significant confusion about the source of one of the contaminated wells in a nursery that was up-gradient or cross-gradient from the gas station in question. Reverse particle tracking identified another source further up-gradient from the gas station that could explain the MTBE contamination in the nursery as well as residential wells down-gradient of the gas station.