The sensitivity of remedial strategies to design criteria

The specific criteria for design of systems for the remediation of contaminated ground water can affect the cost, configuration, and feasibility of the remedial system. Two important design criteria are the degree of remediation required, as measured by water concentration, and the time by which compliance must be achieved, In this paper the impact of these criteria on remedial design is studied for a hypothetical pump-and-treat remedial system applied to a simplified model of a large organic solvents plume in Tucson, Arizona. The analysis is performed by combining two-dimensional numerical flow and transport modeling with nonlinear optimization, The use of optimization provides a means of systematically varying design criteria in an experimental framework, Based on the data for this site? variation of the concentration standard over one order of magnitude can affect the optimal cost by as much as 220%. Change in the time to achieve compliance over less than one order of magnitude can affect optimal cost by as much as 175% and in some cases can produce problems which are infeasible due to physical or technical limitations, Under some conditions, a time to achieve compliance can be identified which has minimum cost, Changes in the design criteria are also shown to have significant impact on the distribution of steady pumping rates among the individual wells.