LNAPL volume in the petroleum-contaminated groundwater system-A modeling and experimental study

摘要

LNAPLs, or light non-aqueous phase liquids, are less dense than water. They can co-exist with water in the aquifer, which are hydrocarbons presenting potential health, resource, and environmental risks. Examples of LNAPL are gasoline, diesel, motor oils, and similar materials. For many decades, the oil production industry has recognized that LNAPLs accidentally released to the subsurface remain in porous media. The study of the distribution of LNAPL in contaminated soil began in the I930s. At that time, LNAPL was considered like "pancakes" over groundwater table. In the past two decades, several methods have been studied to analyze the actual LNAPL thickness present in wells or groundwater and the LNAPL volume in petroleum-contaminated sites. However, previous studies were lack of consideration of the heterogeneous characteristics of the soil. Also few model validations could be found. A new oil volume computation method is developed in the present study, based on an integrated analysis of oil properties, the characteristics of subsurface porous media, and the interactions between oil, soil, and groundwater. Quantitative analyses and tools are thus provided to quantify LNAPL volumes residing in the petroleum-contaminated groundwater system. Importantly, a pilot-scale experiment was set up and conducted in the Environmental Engineering laboratory at Concordia University with actual oil spills and measurements. The developed model has been tested and validated through the pilot-scale experiment and applied to a real petroleum-contaminated site. In addition, a user-friendly modeling system has been developed in the present study. The developed modeling tool can be used to identify the field distribution of LNAPL and its volume present in the soil and groundwater system. The approach can support effective LNAPL recovery action at the contaminated site and thus help solving oil spill contamination problems for the management of groundwater resources