Equity was comfortable with the Technical Committee reports but wanted to confirm the data by having a site specific ARD (Acid Rock Drainage) model developed for their site. The model development was completed in 1991 and calibrated to the historical data. Model runs were completed for till, uncompacted clay and compacted clay covers. This paper presents information regarding the general structure of the ARD model, estimates of ARD production by the model for the various cover scenarios, and compares the model results with several empirical estimates.