Particle travel times of contaminants incorporated into a planning model for groundwater plume capture

Abstract

In problems of groundwater contamination, the cost of long-term remediation can run into millions of dollars. Often the objective of the cleanup strategy involves minimizing or constraining the time it takes to remove all contaminants from the aquifer. Here, a planning model for the withdrawal of contaminated groundwater is presented that enables one to consider remediation problems in which cleanup time is an important component. An existing quasi-analytic solution for advective contaminant transport is combined with nonlinear optimization to determine the distribution of pumping and injection rates. Although the simulation model is simple, its combined use with the optimization procedure is a useful tool. Examples demonstrate how cleanup time as a management variable can dictate the design of the restoration system. The relationship between pumping rates and the ultimate cleanup time proved to be a highly nonlinear function. Inspection of the “cleanup time surface” for a reduced problem provides insight into the nature of this nonlinearity and how it influences the selected restoration design. Analysis indicated that increasing the total pumping rate can result in an increase in total cleanup time due to the deflection of contaminant travel paths.