To satisfy the Resource Conservation and Recovery Act (RCRA) ground-water monitoring regulations, a hazardous waste management facility must have a ground-water monitoring system consisting of at least one upgradient and three downgradient wells and show that the downgradient wells are capable of immediately detecting a statistically significant amount of contamination at the water table. Because the regulations are subjective, it is often difficult for the owner/operator and the regulator to assess whether a monitor-well network satisfies the regulations. A probabilistic strategy is presented which satisfies the regulations and attempts to minimize subjectivity in evaluating the performance of a monitor-well network.

The proposed strategy is based on a determination of the likely ground-water flow paths through both the unsaturated and saturated zones and ground-water travel times. The approach involves three stages of analysis: 1) optimization of monitor well location, 2) evaluation of the sampling interval, and 3) assessing the monitor-well network performance through time.