Primary Controlling Factors and Statistical Modeling of Plume Stability for BTEX in Typical Phreatic Aquifers

Whether the groundwater pollution plume of a contaminated site or a regional area can be stabilized and the stability characteristics of the plume would directly determine the feasibility of the natural attenuation restoration. In this study, a typical aquifer structure with a phreatic aquifer, an impermeable aquifer, and a confined aquifer from top to bottom was constructed to simulate the migration and diffusion of the constant source pollution plume of phreatic water. The stable area, stable concentration and starting stable time of the groundwater pollution plume were taken as characteristic variables. Firstly, the sensitive factors were identified from numerous influence factors through sensitivity analysis method. Secondly, orthogonal experiments were used to identify the main controlling factors. Finally, the multiple regression model was used to construct the quantitative statistical relationship for characteristic variables. The results show that the common primary controlling factors are the degradation coefficient, dispersivity, seepage velocity and the source concentration. Moreover, there are adequate statistical relationships between the characteristic variables and the primary controlling factors. The statistical models characterized by different numbers of factors can be used to predict the characteristic variables. This study would provide an important basis for optimization of the site pollution control and effective remediation which are based on natural attenuation remediation.