Evaluation of subsurface modeling application at CERCLA/RCRA sites

Commonly observed aspects of ground-water model misuse are explored by reviewing twenty model application reports for CERCLA and RCRA sites. The observed aspects of misuse were categorized as: inadequate understanding of (1) the governing differential equations and the associated boundary and initial conditions, (2) conceptualization, (3) input parameter estimation and model calibration, (4) sensitivity and uncertainty analysis, (5) model selection and inherent model limitations, and (6) interpretation of modeling results. Among these identified categories, uncertainty in input parameter value estimation and insufficient sensitivity analysis were observed most frequently. The study results show a greater need for enhanced and continuing education in ground-water model application. It is recommended that stricter guidelines for quality control and quality assurance program for model application be developed. In addition, dissemination of the existing model guidelines should also be enhanced.