GROUNDWATER MONITORING STRATEGIES FOR VARIABLE VERSUS CONSTANT CONTAMINANT LOADING FUNCTIONS

Contaminant plumes were derived for constant and variable loading func tions at locations within a landfill. Annually, the alternative loadin g functions injected the same volume of contaminated water. Mass trans port modeling was used to evaluate the detection efficiencies of 25 mo nitoring transects, spaced evenly between the landfill and a downgradi ent compliance boundary. Respectively, the most efficient transects (r equiring the fewest monitoring wells) for constant and variable loadin g were located at 60-64 and 40 percent of the distance to the complian ce boundary. The mean detection efficiency was 29 percent higher for v ariable loading, but the variation in detection efficiency was similar for constant and variable loading. At the most efficient transects, t he minimum number of detection wells was 20 percent lower for variable loading. Given the influence of source loading on monitoring efficien cy, alternative loading functions should be considered when designing detection monitoring networks in aquifers.