SIMULATION OF GROUNDWATER-FLOW AND CONTAMINANT TRANSPORT AT A LANDFILL SITE USING MODELS

Numerical and analytical modelling studies were conducted for the anal ysis of groundwater flow and contaminant transport at the Innisfil lan dfill site in the Town of Innisfil, County of Simcoe, in Ontario, Cana da. Previously conducted field studies categorized the upper stratigra phy at the site into three units: upper sand unit, upper silt/clay uni t and Intermediate Sand unit. Essentially horizontal groundwater movem ent in the two sand units and vertical downward flow in the silt/clay unit were reported by the field hydrogeologists. In the following, app lication of three computer models (FLOWPATH, USGS MOC and POLLUTE) for the simulation of the groundwater flow and contaminant transport proc esses at the Innisfil landfill site is described. The paper focuses on the calibration of groundwater flow and contaminant transport systems , and demonstrates how the insight gained during the contaminant trans port calibration was used to improve the initial groundwater flow char acterization of the hydrogeological system.