The main objective of this paper is using ArcMap GIS, from Environmental Sciences Research Institute (ESRI), and Geopack as an efficient way to generate contour lines and maps for the underground formation surfaces (e.g. clay unit), water table and different water quality maps of groundwater applied to Ottawa landfill site, Canada. Based on stratigraphical description (well logs) of monitoring wells, there are about 200 monitoring wells in this area, and on monitoring observation, three main aquifers (shallow, deep and bedrock) were assigned under and around of the landfill site. By using available borehole data and Geopack, different variogram models were generated. Then by using the best variogram, based on the variance output map, and Spatial Analyst of ArcGIS, contours of the clay unit surfaces, thickness of the clay unit between shallow and deep aquifers, clay layer windows, and groundwater surfaces were generated. Values of nugget effect, sill and range were calculated in Geopack and were applied in contouring by Kriging in ArcGIS. In this paper, the leachate influence on groundwater was assessed on the basis of Cl-, DOC, EC, and pH output maps of ArcGIS. The shallow and deep aquifers were contaminated somewhere in the north and beneath of Ottawa landfill site. Coupling a geostatistical software such as Geopack to a GIS such as ArcGIS can help to better understand and model hydrogeological parameters and study the contamination patterns and their relationship to other factors in this area.

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