A multiple indicator conditional simulation technique is used to generate realizations of hydrofacies units in a two-dimensional section of the fluvial, unconfined aquifer on the Hanford Site, Richland, WA. Two conceptual geologic models are considered and evaluated for spatial connectivity. The two conceptual models yielded different probabilities of occurrence for three ''families'' of simulations with distinct styles of connectivity. Critical ground-water flow paths of each simulated section are evaluated as the paths with the highest percent of high hydraulic conductivity hydrofacies. The effective hydraulic conductivity of these critical paths is evaluated analytically by computing harmonic averages. Estimated groundwater travel times are consistent with the observed rate of plume migration in the field. This procedure can be used to evaluate the probability of occurrence of alternative paths for contaminant transport as input to risk assessments, and design of characterization programs and remediation systems.
