Contaminant Arrival Times at Wells G and H
Each expert had at his disposal the same water-level, streamflow, and permeability data upon which to make these calculations. Each expert, however, used a different approach to making the calculations. One expert relied on the results of a 1-dimensional model that assumed steady-state conditions within the flow system and spatially uniform values of permeability, porosity, and hydraulic gradient. One expert used the water-level and streamflow data to construct potentiometric surface maps and a potentiometric profile to show that groundwater could not flow under the Aberjona River. The third expert incorporated all the site-specific water-level, streamflow, and permeability data into a 3-dimensional computer model that accounted for the transient character of the flow system due to temporal variations in recharge from precipitation, and changes in the pumping rates of wells G and H and their periodic use (Bair, 2001 (Acrobat (PDF) 4MB Jun18 09)). Excerpts from the trial testimony of these three experts can be found in Resource Collections under the Trial Testimony section.(Bair, 2001) (Acrobat (PDF) 4MB Jun18 09). The crux of the case came down to which expert did they understand and/or believe in terms of his calculation of contaminant arrival times at wells G and H. Learning Modules 3, 5, and 8 involve constructing the maps and performing the calculations to make (simplistic) estimates of contaminant arrival times in wells G and H.