Optimizing groundwater monitoring systems for landfills with random leaks under heterogeneous subsurface conditionsOptimisation des dispositifs de surveillance des eaux souterraines sous des décharges à fuites aléatoires sur sub-surface hétérogèneOptimización de sistemas de monitoreo de agua subterránea para rellenos sanitarios con filtraciones aleatorias bajo condiciones subsuperficiales heterogéneasالاستفادةالمثلىمنأنظمةرصدالمياهالجوفيةعندمدافنالنفاياتمنمصدرتسريباتعشوائي فيظلظروفغيرمتجانسةللتكويناتالجيولوجيهتحتسطحالأرض非均质地下条件下随机泄漏垃圾填埋场的地下水监测系统优化Optimização dos sistemas de monitorização de água subterrânea em aterros com fugas aleatórias em condições subsuperficiais heterogéneas

Landfills are one of the most common human activities threatening the natural groundwater quality. The landfill may leak, and the corresponding plumes may contaminate an area, entailing costly remediation measures. The objective of the installation of monitoring systems at landfill sites is to detect the contaminant plumes before they reach the regulatory compliance boundary in order to enable cost-effective counter measures. In this study, a classical decision analysis approach is linked to a stochastic simulation model to determine the optimal groundwater monitoring system given uncertainties due to the hydrogeological conditions and contaminant source characteristics. A Monte Carlo approach is used to incorporate uncertainties. Hydraulic conductivity and the leak location are the random inputs of the simulation model. The design objectives are to: (1) maximize the detection probability, (2) minimize the area of contamination at the time of detection, and (3) minimize the total cost of the monitoring system. A synthetic test case based on a real-world case in the Netherlands is analyzed. The results show that monitoring systems located close to the source are optimal except for the cases with very high unit installation and sampling cost and/or very cheap unit remediation.