NUMERICAL INVESTIGATIONS ON THE FACTORS AFFECTING TRANSPORT OF GAS PHASE PLUMES ORIGINATING FROM A RESIDUAL NAPL SOURCE IN THE SUBSURFACE

Lee, Kun Sang

doi:2004.9.5.214

Environmental Engineering Research 2004;9(5): 214-222. DOI: https://doi.org/10.4491/eer.2004.9.5.214

NUMERICAL INVESTIGATIONS ON THE FACTORS AFFECTING TRANSPORT OF GAS PHASE PLUMES ORIGINATING FROM A RESIDUAL NAPL SOURCE IN THE SUBSURFACE

Kun Sang Lee^†

Div. of Civil and Environmental Engineering Kyonggi University, Suwon, Kyonggi 443-760, Korea

Corresponding Author: Kun Sang Lee ,Tel: +82-31-249-9738, Fax: +82-31-244-6300 , Email: kslee@kyonggi.ac.kr

Received: July 18, 2004; Accepted: September 19, 2004.

ABSTRACT

Residual sources of nonaqueous-phase liquids (NAPLs) in the unsaturated zone can create soil gas plumes which act as a long-term source of soil gas and groundwater. A mathematical model is developed for predicting soil gas concentrations that arc a product of gas phase plumes that originate from an immobilized NAPL in the unsaturated zone. Multiphase How, density-dependent gas flow, and interphase mass transfer between liquid and gas are included in the model. Extensive simulations with a finite-element based numerical model were performed to estimate the soil gas phase plumes resulting from an immobilized trichloroethylene (ICE) residual located in a hypothetical laboratory-scale medium. Effects of various parameters are evaluated to highlight some of the important phenomena associated with the transport of gas phase plume in variably saturated media. The simulation results indicate that the gaseous plume is very sensitive to soil texture, the locations of the residual NAPL source and water table, and variations in infiltration and evaporation rates.

Keywords: nonaqueous-phase liquid (NAPL) | unsaturated zone | residual source | transport | trichloro¬ethylene (ICE)