Dual Domain Transport Impacts on Projected Groundwater Remediation
Dual Domain Transport Impacts on Projected Groundwater Remediation
Presented on Tuesday, May 6, 2014
Contaminant plume “tailing” is a commonly used description of a groundwater cleanup that proceeds slower than expected, based on routine contaminant transport analysis. One cause of tailing is slow diffusion of dissolved contamination from lower permeability portions of an aquifer into higher permeability zones that may continue for a long time after remediation of the source. Diffusive exchange of contaminant mass may occur between a relatively low permeability rock matrix and high permeability fractures in a bedrock aquifer or between silt or clay lenses and adjacent high permeability sandy fractions within a heterogeneous overburden aquifer.
Using a dual domain transport algorithm developed in DYNSYSTEM, mass transport simulations were conducted for an industrial remediation site to evaluate the potential impacts of dual domain transport on the duration of groundwater remediation and to inform remediation operation cost projections.
Test simulations of historical plume development were used to estimate an appropriate range of dual domain parameter values for future projection simulations. Projection simulation results indicated that factoring in matrix diffusion has the potential to more than double the estimated time required to achieve the remedial objective and system shutdown compared with the original estimate based on conventional transport modeling.