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ARS Home » Pacific West Area » Tucson, Arizona » SWRC » Research » Publications at this Location » Publication #57340
Title: CALIBRATION AND TESTING OF SIMULATION MODELS FOR EVALUATION OF TRENCH CAP DESIGNS

Author
item PAIGE G B - UNIV. OF ARIZ.
item STONE J J - UNIV. OF ARIZ.
item LANE L J - 5342-45-00
item HAKONSON, T - COLO. STATE UNIV.

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Simulation models are often used to evaluate the long-term performance of landfill cover designs for low-level radioactive waste sites when data are not available. However, it is important to test the simulation models and their ability to simulate landfill cover performance for an extended period of time. Two simulation models used in a prototype decision support system m(PDSS) to be used by risk managers to evaluate landfill cover designs were tested using data from a four-year field demonstration study at Hill Air Force Base in Layton, Utah. The HELP (Hydrologic Evaluation of Landfill Performance and CREAMS (Chemicals, Runoff, and Erosion from Agricultural Management Systems) models were tested using annual water balance and erosion parameters for two alternative cover designs. The results were reasonable for the length of the data set. Simulations were run for a two hundred-year period to test the long-term stability of the models. The annual average values determined by the models stabilized within sixty years. The results of the long-term test are important for the PDSS which uses the annual average values from the simulation models to evaluate alternative cover designs. In order to fully validate and test the simulation models, other data sites of landfill covers in a variety of climates are needed.

Technical Abstract: A prototype decision support system (PDSS) using multi-objective decision theory and embedded simulation models is being developed to evaluate landfill cover designs for low-level radioactive waste disposal sites. In order to evaluate the performance of the PDSS, the simulation models, which are used to parameterize the decision model when data are not available, 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 Agricultural Management Systems) models. Data from a four year field demonstration study of landfill cover performance at Hill Air Force Base was used to calibrate the linked simulation models. The models were calibrated using water balance and erosion parameters for two alternative designs, a control soil cover and a modified EPA RCRA design. Simulations were run using the calibrated model parameters for a two hundred year period to test the long term stability of the models. The largest variance from the long-term mean was for runoff and sediment yield. The running mean 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 evaluated. The results of the calibration and long-term test were reasonable for the length of the Hill Air Force Base data set.