Analysis of solute transport toward a partially penetrating extraction well in an anisotropic aquifer

• Main Authors: Chia-Lun Wu, 吳嘉倫
• Other Authors: Jui-Sheng Chen
• Format: Others
• Language: zh-TW
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/nrv3nz

碩士 === 國立中央大學 === 應用地質研究所 === 97 === Pump-and-treat techniques are often applied to extract the polluted groundwater and to reduce the concentration of the contaminants to an acceptable level. The design of an effective and efficient pump-and-treat system requires that the recovery wells collect the contaminant and withdraws the minimum amount of clean water adjacent to the contaminant plume. The installation of a partially penetrating well in which only a portion of the well casing is screened is becoming more common because it is very often the case that only a portion of the vertical thickness of the aquifer is contaminated. In this study, a novel mathematical model describing the solute transport around a partially penetrating well is presented. To build the new model, the radial and vertical components of the pore water velocity are first computed using an analytical solution for the steady-state drawdown distribution near a partially penetrating well. Next, the obtained radial and vertical components of the pore water velocity are incorporated into a two-dimensional advection-dispersion equation in cylindrical coordinates from which the solute transport equation is derived. The developed model is used to investigate the effects of the site-specific aquifer parameters on solute transport near a partially penetrating well. Results demonstrate that the effect of the partially penetrating well on solute transport is significant when there is a large hydraulic conductivity anisotropy ratio and small longitudinal dispersivity. The mathematical model presented herein provides a useful tool for designing an effective and efficient pump-and-treat system for partially penetrating well.