Ground-Water Contamination Due to Vanishing and Finitesize Continuous Sources

Analytical methods are described to predict the concentrations of effluents released in a two- or three-dimensional groundwater flowfield from a point, line, plane or parallel piped source. The effects of the upper and lower confining boundaries in an artesian aquifer and those of the bedrock and water table in an unconfined aquifer are accounted for by the method of images. The same technique is used to model the contribution of a constant concentration boundary in the flowfield like the one provided by a fully penetrating perennial stream. Using the results of a sensitivity analysis, the number of images at which computations can be truncated without significantly affecting the accuracy of the results is indicated. Examples are provided to illustrate the effect of source configuration, e.g., point, line or plane, and the presence or absence of a fully penetrating perennial stream in the flowfield. To validate the model, concentration isopleths are developed for the release of effluents from an ashpond in a two-dimensional stream-aquifer system an the results are compared with those contained from a finite-element study.