Journal of Soil and Groundwater Environment (한국지하수토양환경학회지:지하수토양환경)

Korean Society of Soil and Groundwater Environment (한국지하수토양환경학회)
권호 표지

Analyses on Solute Transport with the Movement of an LNAPL on the Water Table

지하수면 위의 LNAPL 이동을 고려한 용질이동에 대한 분석

  • 김지훈 (서울대학교 지구환경시스템공학부) ;
  • 최종근 (서울대학교 지구환경시스템공학부)
  • Published : 2003.09.01
Download PDF
⟨ Previous Next ⟩

Abstract

A modified model was developed for solute transport in porous media that can consider the movement of an LNAPL above the water table. From the results of sensitivity analyses with and without considering LNAPL movement, there are some differences according to the hydraulic gradient, the quantity of oil leakage and dispersivity. The mean deviation between the model in this study and a conventional model without LNAPL movement increases as the hydraulic gradient decreases and the quantity of oil leakage increases. Variation of dispersivity has no influence on the magnitude of the mean deviation. However, the spatial distribution of the deviation between the two models is wider as dispersivity increases. Furthermore, groundwater is at high risk of contamination in the vertical direction in the case that transverse dispersion value is large. A conventional model underestimates the concentration of solute in an aquifer where the movement of an LNAPL cannot be negligible: Based on the study results, it is important to understand how fast the LNAPL moves on the water table for realistic prediction of solute transport in an aquifer with the movable LNAPL on the water table.

지하 유류저장탱크에서 유류가 지속적으로 누출되는 경우에는 지하수 이동에 비해서 LNAPL의 이동을 무시할 수 없다. 본 연구에서는 지하수면 위에서 LNAPL의 이동을 고려한 수정된 용질이동 모델을 개발하였다 LNAPL 이동을 고려하지 않는 기존 모델과 비교한 결과 수두 구배, 누출되는 기름의 양, 분산지수에 따라 두 모델은 차이점을 보였다. 수두 구배가 낮을수록, 누출되는 유류의 양이 증가할수록 수정된 모델과 기존 모델 사이의 평균편차가 증가하였다. 분산지수가 변화함에 따라서 평균편차는 변하지 않았지만, 분산지수가 증가할수록 두 모델 사이의 편차는 공간적으로 보다 넓게 나타났다. 수직방향으로의 분산이 크게 나타날 경우에는 LNAPL의 이동을 고려한 모델과 이동을 고려하지 않은 모델과의 차이가 지하수 유동 방향뿐만 아니라 수직방향으로도 크게 나타났다. 결국 LNAPL의 이동을 무시할 수 없는 지하환경에서는 기존의 모델을 가지고 용질이동을 모사할 경우 실제보다 농도가 낮게 추정될 가능성이 높다. 이 연구의 결과로 LNAPL이 지하수면 위에서 얼마나 빨리 이동하는지 아는 것이 올바른 오염물의 농도 예측에 중요하다는 것을 파악하였다.

Keywords

References

  1. Baehr, A. L. and Corapcioglu, M. Y., 'Compositional Mul-tiphase Model for Groundwater Contamination by Petro-leum Products 2. Numerical Solution,' Water ResourcesResearch, 23(1), pp. 201-213 (1987) https://doi.org/10.1029/WR023i001p00201
  2. Corapcioglu, M. Y. and Baehr, A. L., 'Compositional Multiphase Model for Groundwater Contamination by Petroleum Products 1. Theoretical Consideradons,' Water Resources Researvh, 23(1), pp. 191-200 (1987) https://doi.org/10.1029/WR023i001p00191
  3. Bear, J., Ryzhik, V., Braester, C., and Entov, V., 'On the movement of an LNAPL lens on the water table,' Transport in Porous Media, 25, pp. 283-311 (1996) https://doi.org/10.1007/BF00140985
  4. Bear, J. and Ryzhik, V, 'On the Displacement of NAPL Lenses and Plumes in a Phreatic Aquifer,' Transport in Porous Media, 33, pp. 227-255 (1998) https://doi.org/10.1023/A:1006544629038
  5. Bradford, S. A. and Abriola, L. M., 'Dissoludon of Residual Tetrachloroethylene in Fractional Wettability Porous Media: Incorporation of Interfacial Area Estimates,' Water Resources Research, 37(5), pp. 1183-1195 (2001) https://doi.org/10.1029/2000WR900374
  6. Zhou, D., Dillard, L. A., and Blunt, M. J., 'A Physically Based Model of Dissolution of Nonaqueous Phase Liquid in the Saturated Zone,' transport in Porous Media, 39, pp.227-255 (2000) https://doi.org/10.1023/A:1006693126316
  7. Knutson, C. E., Werth, C. J., and Valocchi, A. J., 'Pore-scale Modeling of Dissolution from Variably Distributed Nonaqueous Phase Liquid Blobs,' Water Resource Research, 37(12), pp. 2951-2963 (2001) https://doi.org/10.1029/2001WR000587
  8. Seagren, E. A. and Rittmann, B. E., 'A Chtical Evaluation of the Local-Equilibrium Assumption in Modeling NAPL-Pool Dissolution,' J. of Contaminant HydroIogy, 39, pp.109-135 (1999) https://doi.org/10.1016/S0169-7722(99)00026-1
  9. Brauner, J. S. and Widdowson, M. A. 'Numerical Simula-tion of a Natural Attenuation Experiment with a Petroleum Hydrocarbon NAPL Source,' Ground Water, 39(6), pp.939-952 (2001) https://doi.org/10.1111/j.1745-6584.2001.tb02482.x
  10. Jang, M. and Choe, J., 'Stochastic Optimixation for Global Minimization and Geostatistical Calibradon,' J. of Hydrology, 266, pp. 40-52 (2002) https://doi.org/10.1016/S0022-1694(02)00115-4
  11. Jang, M., Lee, J., Choe, J., and Kang, J. M., 'Modeling of Solute Transport in a Single Fracture using Streamline Simulation and Experimental Validadon,' J. of Hydrology, 261, pp. 74-85 (2002) https://doi.org/10.1016/S0022-1694(02)00015-X
  12. 최종근,공간정보모델링:크리깅과 최적화, 1판, 구미서관, 서울 (2002)
  13. Kool, J. B. and Parker, J. C., 'Development Evaluation of Closed-Form Expressions for Hysteric Soil Hydraulic Properties,' Water Resources Research, 23(1), pp. 105-114 (1987) https://doi.org/10.1029/WR023i001p00105
  14. Bedient, P. B., Rifai, H. S. and Newell, C. J., Ground Water Contamination: Transport and Remediadon, 1st Ed., Prentice Hall PTR, Englewood Cliffs, New Jersey (1994)
  15. Domenico, P. A. and Schwartz, F. W., Physical and Chemical Hydrogeology, 1st Ed., John Wiley & Sons Inc., New York, USA (1990)