CALIBRATION AND TESTING OF SIMULATION-MODELS FOR EVALUATION OF TRENCHCAP DESIGNS

A prototype decision support system (PDSS) using multi-objective decis ion theory and embedded simulation models is being developed to evalua te landfill cover designs for low-level radioactive waste disposal sit es. To evaluate the performance of the PDSS, the simulation models, wh ich are used to parameterize the decision model when data are not avai lable, must be calibrated and tested. The two linked simulation models embedded in the PDSS are the HELP (hydrologic evaluation of landfill performance) and CREAMS (chemicals, runoff, and erosion from agricultu ral management systems) models, Data from a field demonstration study at Hill Air Force Base were used to calibrate the simulation models, T he models were calibrated using water balance and erosion parameters f or two alternative designs, a control soil cover and a modified USEPA Resource Conservation and Recovery Act design, Simulations were run us ing the calibrated model parameters for a 200-yr period to evaluate th e long-term performance of the models. The progressive annual average for all of the output parameters was within the 95% confidence limits of the long-term mean by Year 60 for both of the cover designs evaluat ed, The results of the calibration and long-term evaluation of the sim ulation models were reasonable for the length of the data set. To full y validate and test the simulation models, other data sets of landfill covers in a variety of climates are needed.