OPTIMAL GROUNDWATER REMEDIATION WITH WELL LOCATION AS A DECISION VARIABLE - MODEL DEVELOPMENT

A new formulation for the optimal design of aquifer remediation strate gies is presented in which the well location problem is solved by expl icitly incorporating the spatial coordinates and pumping rates of well s as decision variables. The Hermite interpolation function is used to represent the well location as a continuous function of space and to facilitate the incorporation of a barrier function for containing the well location within the model domain. The management model combines t he numerical simulation of groundwater flow and contaminant transport with optimization methods to select the optimal location and pump rate by moving each well within the problem domain unrestricted by nodal l ocation. The details of the numerical implementation required to incor porate well locations as decision variables in a two-dimensional Galer kin finite element discretization of the groundwater flow and contamin ant transport equations are presented. The approach is contrasted with an optimization model for groundwater quality management in which opt imal well locations are chosen from a number of preselected candidate locations. A simple hypothetical problem is solved to compare these tw o approaches and examine the numerical behavior of the new formulation . The results indicate that a formulation in which well location is a decision variable can be implemented and that improved solutions are p ossible. The results are also used to demonstrate how this approach ca n be used to solve problems in which the initial costs of well install ation are included.