The second largest contaminated groundwater plume in Alaska exists in a discontinuous permafrost aquifer in the area of North Pole, Alaska. The aquifer is contaminated with sulfolane; a compound used in the refining of petroleum.
As a part of remediation a relatively large monitoring well network has been installed to track the dispersion of the contaminant. Monitoring results revealed that the plume is much more dispersed in the lateral direction representing the contaminant presence in suprapermafrost and subpermafrost portions of the aquifer. Previous studies of this aquifer has shown that contaminant thawed through taliks exists in different areas of the plume providing connectivity between the sub and suprapermafrost portions of the aquifer.
The objective of this study is to determine the pathway for sulfolane to reach the subpermafrost portion of the aquifer, the vertical and horizontal flow gradients in key locations of the plume are evaluated. Asymmetrical errors in water level measurements due to the frost heave and thaw settlement of monitoring wells are reduced by Monte Carlo analysis. A three dimensional model with flow vector visualization of groundwater with discontinues permafrost has been created. The effect of seasonal variability in the flow pattern provided new understandings of the contamination at plume boundary. With a precise flow vector visualization, seasonal variability and measured concentrations of sulfolane, a cutting-edge groundwater flow pattern in discontinuous permafrost regions has been determined.
This is the fundamental study that has investigated groundwater flow at the interface with permafrost bodies in areas of discontinuous permafrost. Understanding this interaction is key to our understanding of contaminant transport, aquifer recharge, and resource development in subarctic environments.