EVALUATION OF A PROTOTYPE DECISION-SUPPORT SYSTEM FOR SELECTING TRENCH CAP DESIGNS

A computer-based prototype decision support system (PDSS) to assist th e risk manager in selecting an appropriate trench cap design for waste disposal sites is evaluated. The selection of the ''best'' design amo ng feasible alternatives requires consideration of multiple and often conflicting objectives, The methodology used in the selection process consists of: selecting and parameterizing decision variables, using da ta, simulation models, or expert opinion; selecting feasible trench ca p design alternatives; ordering the decision variables and ranking the design alternatives, The simulation models incorporated in the PDSS a re the Hydrologic Evaluation of Landfill Performance (HELP) model whic h is used to simulate the trench cap water balance and the Chemicals, Runoff, and Erosion from Agricultural Management Systems (CREAMS) eros ion component that is used to simulate trench cap erosion. The decisio n model is based on multi-objective decision theory and uses a unique approach to order the decision variables and rank the design alternati ves. The PDSS is evaluated using the Hill Air Force Base landfill cove r demonstration project, The water balance and surface erosion of four alternative landfill cover designs were monitored for a 4-yr period, Two of the cover designs were used to calibrate and test the simulatio n models, The results of the PDSS, using both data from all four desig ns and long-term simulations from two of the designs, illustrate the r elative advantages of each of the cover designs and which cover is the ''best'' alternative for a given set of criteria and a particular imp ortance order of those decision criteria.