Groundwater detection monitoring system design under conditions of uncertainty

Abstract

Landfills represent a wide-spread and significant threat to groundwater quality. In this thesis a methodology was developed for the design of optimal groundwater moni-toring system design at landfill sites under conditions of uncertainty. First a decision analysis approach was presented for optimal design of groundwater monitoring sys-tems under conditions of uncertainty. Uncertainties in the hydrogeology and contami-nant source were incorporated in the model using Monte Carlo simulations. Maximiz-ing the probability of detecting contaminant plumes, minimizing the contaminated area, and the total cost of the monitoring system (i.e., construction, maintenance, and remediation cost, if necessary) were the conflicting objectives. It was observed that the most efficient design for detection monitoring should consist of rather a large number of wells located close to contaminant source. Then, a new monitoring ap-proach was proposed and implemented to find out how to improve the efficiency of groundwater monitoring systems, particularly the efficiency of 3-well system that ful-fils the minimum regulatory requirement. To increase the interception of contaminant plumes at early stages by broadening the capture zone of monitoring well(s) simply by continuous pumping from the monitoring well(s) with a small pumping rate is the essence of this approach. The results of analysis showed that the efficiency of the monitoring system improves significantly by the application of the proposed monitor-ing approach. Then the former decision model considering the current conventional monitoring approach, was extended by implementing this new monitoring approach in the model. Finally, the applications of both simulation-decision models to Maarsber-gen Landfill site (The Netherlands) were presented.