Simulation of NAPL migration and persistence in the overburden and fractured bedrock at Smithville, Ontario
- Waterloo Centre for Groundwater Research, Ontario (Canada)
At the Smithville site, an estimated 30,000L of DNAPL has migrated through the approximately six meters of clay overburden and entered the underlying fractured carbonate bedrock. Both the depth of penetration and the lateral extent of the DNAPL within the underlying bedrock are uncertain, and difficult to ascertain directly due to the inherent dangers of remobilization of NAPL when sampling in a NAPL source zone. Thus, numerical modelling becomes an important tool in attempts to characterize the pathways and DNAPL distribution for various probable release scenarios. A fully 3D, three-phase compositional model has been developed which allows the simulation of multiphase, multi-component contaminant problems in porous media with discrete fractures. The process of matrix diffusion, which has been shown to cause the relatively rapid disappearance of NAPL from fractures is included in the model. Advective and dispersive/diffusive fluxes of all three fluid phases (gas, NAPL, water) within the fracture network, as well as between the fractures and the matrix are included, as are capillary pressure differences between the fracture and the matrix. Results will be presented showing how DNAPL migration and persistence in a single vertical fracture through clay overburden is affected by factors such as matrix porosity, matrix retardation, DNAPL release rate, and fracture aperture. As well, results of 2D simulations involving DNAPL migration and aqueous phase plume movement through the fractured clay and into the underlying fracture bedrock will be presented.
- OSTI ID:
- 353680
- Report Number(s):
- CONF-970677--
- Country of Publication:
- United States
- Language:
- English
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