TY - JOUR
T1 - Analysis of water saturation, napl content, degradation half-life, and lower boundary conditions on voc transport modeling
T2 - Implications for closure of soil venting systems
AU - DiGiulio, Dominic C.
AU - Varadhan, Ravi
PY - 2001
Y1 - 2001
N2 - Simulations using a one-dimensional, analytical, vadose zone, solute-transport screening code (VFLUX) were conducted to assess the effect of water saturation, NAPL saturation, degradation half-life, and boundary conditions at the vadose zone/groundwater interface on model output. At high initial soil concentrations, model output was significantly affected by input parameters and lower boundary conditions yet still resulted in consistent decision-making to initiate or continue venting application. At lower soil concentrations, however, typical of what is observed after prolonged venting application, differences in model input and selection of lower boundary conditions resulted in inconsistent decision-making. Specifically, under conditions of low water saturation, use of a first-type, time-dependent lower boundary condition indicated that the primary direction of mass flux was from ground water to the vadose-zone, suggesting little benefit from continued venting application. Use indicate continued mass flux from the vadose zone to ground water, suggesting a continued need for venting application. In this situation, sensitivity analysis of input parameters, selection of boundary conditions, and consideration of overall objectives in vadose zone modeling become critical in regulatory decision-making.
AB - Simulations using a one-dimensional, analytical, vadose zone, solute-transport screening code (VFLUX) were conducted to assess the effect of water saturation, NAPL saturation, degradation half-life, and boundary conditions at the vadose zone/groundwater interface on model output. At high initial soil concentrations, model output was significantly affected by input parameters and lower boundary conditions yet still resulted in consistent decision-making to initiate or continue venting application. At lower soil concentrations, however, typical of what is observed after prolonged venting application, differences in model input and selection of lower boundary conditions resulted in inconsistent decision-making. Specifically, under conditions of low water saturation, use of a first-type, time-dependent lower boundary condition indicated that the primary direction of mass flux was from ground water to the vadose-zone, suggesting little benefit from continued venting application. Use indicate continued mass flux from the vadose zone to ground water, suggesting a continued need for venting application. In this situation, sensitivity analysis of input parameters, selection of boundary conditions, and consideration of overall objectives in vadose zone modeling become critical in regulatory decision-making.
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U2 - 10.1111/j.1745-6592.2001.tb00644.x
DO - 10.1111/j.1745-6592.2001.tb00644.x
M3 - Article
AN - SCOPUS:0034747339
SN - 1069-3629
VL - 21
SP - 83
EP - 91
JO - Ground Water Monitoring and Remediation
JF - Ground Water Monitoring and Remediation
IS - 4
ER -