In situ Measurement of the Coefficient of Molecular Diffusion in Fine-Grained Till
In situ diffusion testing was performed on two wells completed in diffusion-dominated zone of a till aquitard. Laboratory diffusion cell tests were conducted on core samples obtained from the screened zones of the diffusion wells. Diffusion testing was completed using conservative isotopes of water as tracers.
A finite element model was used to back-analyze results of laboratory and field experiments to determine the De values that best describe each system. Comparison of the field results with the laboratory results obtained from this study as well as previous studies indicate the field system is a useful method for measurement of De.
Back-analysis of a previously determined large-scale field deuterium profile for this aquitard showed very precise measurement of De is not required for estimation of contaminant transport in thick till aquitard systems. More accurate measurement may be more useful for barrier systems such as clay liners or slurry walls, where the characteristics of the diffusion-dominated zone are easier to define and the transport path is shorter relative to the transport time.
Advisor:Hendry, M. Jim; Barbour, S. Lee
School:University of Saskatchewan
School Location:Canada - Saskatchewan
Source Type:Master's Thesis
Keywords:i in situ diffusion clay aquitard
Date of Publication:07/31/2007