HR: 1340h
AN: H53A-1229    [Abstracts]
TI: Effect of Well Bore Mixing on Formation Decontamination by Pumping
AU: * Chen, J
EM: jschen@app.geo.ncu.edu.tw
AF: Institute of Applied Geology, National Central University, No. 300, Jungda Rd., Jhongli city, Taoyuan, 320 Taiwan
AU: Liang, C
EM: sc048@mail.fy.edu.tw
AF: Department of Environmental Engineering and Science, Foo-Yin University, No.151 Chin-Hsueh Rd., Ta-Liao Hsiang, Kaohsiung, 831 Taiwan
AU: Liu, C
EM: lcw@gwater.agec.ntu.edu.tw
AF: Department of Bioenvironmental Systems Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei, 106 Taiwan
AB: Various techniques have been developed to remediate contaminated groundwater. The conventional means of cleaning up contaminated formation is the ­pump-and-treat­" approach, which uses a series of extraction wells to withdraw contaminated groundwater for above-ground treatment. Given the strong interest in remediation of contaminated formation, models to describe contaminant transport induced by pumping at extraction wells have been formulated and applied to evaluate the efficiency of the pump-and-treat system. As the contaminants enter a large-diameter pumping well,the well bore water will tend to mix and dilute the contaminated groundwater. However,few studies have examined how well mixing volume affects contaminant transport for formation decontamination by pumping. This work presents a novel mathematical model to evaluate the effect of pumped well bore mixing volume on formation decontamination. The model equation is solved by the Laplace transform finite difference method. A sensitivity analysis of the developed model is performed to assess the effect of well bore mixing volume. The well bore volume effect is pronounced for initial plumes with a small maximum contaminated radius, and in media such as bedrock formation where aquifer porosity and longitudinal dispersivity are small. In such systems, the pumped well bore mixing effect reduces the early contaminant concentrations, shifts the peak breakthrough curves to the right and spreading the breakthrough curve, and thus increasing the decontamination time. If such a system does not account for pumped well mixing effect, estimates of decontamination time required to the regulatory level will be inaccurate.
DE: 1832 Groundwater transport
DE: 1894 Instruments and techniques
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting