Effects of Anisotropy on Maximum Extent of Influence of Wells and Dewatered Pits

Models are critical to predicting the likely impact of wells and dewatered pits on environmentally sensitive surrounding areas.  In practice, we usually lack sufficient data to characterize the hydraulic properties outside of the immediate vicinity of the well or pit.  Therefore, we must rely on simplified models to assess likely impacts.  Under these conditions, a typical analysis uses available data to define worst-case bounding conditions and use these results to limit the spatial extent of more detailed investigation.  We show an example of this approach that uses limited hydraulic conductivity and specific yield information to assess the maximum extent of influence due to pumping a well or dewatering a pit for one year.  The results show the importance of considering directional dependence of hydraulic conductivity (anisotropy) in predicting these maximum extents. Finally, we show how the results also impact the design of dewatering efforts.