The objective of this internet seminar is to provide training on an accessible, easy-to-use, and useful tool for modeling matrix diffusion. Low-permeability (low-k) zones can serve as indirect, low-level sources of contamination to transmissive zones as a result of matrix diffusion. The potential for matrix diffusion effects can be seen at virtually any site with heterogeneity in the subsurface, dense non-aqueous phase liquids (DNAPL), or where persistent contaminant concentrations in groundwater after source-zone remediation have been observed. To better equip the community with accessible, useable, and practical models for evaluating matrix diffusion effects, the Environmental Security Technology Certification Program (ESTCP) funded development of the Matrix Diffusion Toolkit. The Toolkit provides planning level estimates of the (1) mass discharge caused by diffusion from a low-k diffusion-dominated unit into a high-permeability advection-dominated unit. Estimates of concentration and mass remaining in the high-permeability unit, after the source is removed, are also provided; (2) contaminant transport via advection and transverse diffusion in the transmissive layer, and (3) transport via transverse diffusion in the low-k zone. Based on the Microsoft Excel platform, the Toolkit is an easy-to-use, comprehensive, free software tool that can assist site personnel to effectively and efficiently estimate the effects of matrix diffusion at their site, and transfer the results to stakeholders. Furthermore, the software can assist project managers in evaluating whether remediation goals are achievable in the short term.
|