APPLICATION OF FACILITY LOCATION THEORY TO GROUNDWATER REMEDIATION

A facility location method developed in this paper derives efficient p umping-well configurations for removing plumes of contaminated groundw ater. The method incorporates a modified version of the Location Set C overing Model (LSCM), with a direction-dependent distance threshold, a nd the theoretical time-dependent capture zone of an extraction well. The objective of the model formulation is to find the locations of the minimum number of wells that capture a plume of known geometry within a specified period of time. A numerical particle tracking scheme is u sed to verify capture for LSCM-derived pumping-well configurations. Th e development of stagnation points or local zones of low velocity gene rally precludes complete contaminant plume removal (that is, a 100 per cent capture efficiency) within a specified time horizon. However, ca pture efficiency can be improved by an iterative procedure in which th e LSCM is constrained to include wells within uncaptured areas identif ied through particle tracking for a previous solution. A removal effic iency of 90 per cent was attained in an application of the approach. T he approach is not difficult to implement, and the formulated integer programming model can be solved with the branch-and-bound method.