3. Geology and Hydrogeology

Figure 3: Geological and hydrogeological setting of the Regina East area (After Christiansen, 1979; Maathuis & van der Kamp, 1988) The stratigraphy, lithology and hydrogeological setting of the Regina area is illustrated in figure 3 (After Christiansen, 1979; Maathuis & van der Kamp, 1988). In ascending order, the bedrock surface in the study area is the Bearpaw Formation (aquitard) deposited in a shallow sea environment during the Cretaceous period. The bedrock is overlain by the Empress Group (aquifer and aquitard) deposited in a non-marine fluvial or lacustrine environment during the Tertiary period of the Cenozoic era. Post this, all deposits are the result of the Pleistocene glaciation of the Quaternary period. The Sutherland Group (aquitard) consists of about 0 to 64 meters of till. Overlying the Sutherland Group is the Saskatoon Group in which lies the Zehner, Regina and Condie aquifer. In the Regina East area, the Saskatoon Group is divided into the Lower Floral Formation, Upper Floral Formation, Battleford Formation and Surficial Stratified Drift. The unconfined Condie aquifer belongs to the saturated sands and gravels of the Condie Moraine within the Battleford Formation and is divided into the East, Central and West units. The Regina aquifer belongs to the sands and gravels of only the Upper Floral Formation, whereas the Zehner aquifer belongs to the sands and gravels of both the Upper and Lower Floral Formation. To the south of Boggy Creek, the Condie aquifer’s east unit overlies the middle section of the Zehner aquifer (Figure 2) and the aquifers are separated by a thick till unit of the Upper Floral Till and Battleford Formation. The Upper Floral Formation (Regina and Zehner aquifer) consists of the Upper Floral Sand and Gravel and is overlain by the Upper Floral Till unit. The Zehner and Regina aquifers are separated by a hydraulic barrier or discontinuity located in Townships 17 and 18, Range 19 (BHL, 2004; Maathuis & van der Kamp, 1988). The discontinuity was established due to the 20 to 30 meters hydraulic head difference between the Regina and Zehner aquifer over lateral distance of 3 to 4 Km (Maathuis & van der Kamp, 1988). There are significant changes in the top and bottom of the Upper Floral Sand and Gravel across this discontinuity and it was interpreted to be a probable result of a collapse structure. The Lower Floral Formation (Zehner aquifer) consists of the Lower Floral Sand and Gravel and is overlain by the Lower Floral Till. The Lower Floral Sand and Gravel is present mainly at the northern part of the Regina East study area and in the Range 18, Township 17 area close to the Boggy Creek reservoir. It is 12 to 107 meters below ground level (m. b.g.l) and about 2.5 to 21 meters thick. As per previous studies, in the northern section of the Zehner aquifer the groundwater in the Upper Floral Sand and Gravel drains into the Lower Floral Sand and Gravel as the two are separated by a thin layer of Lower Floral Till (Maathuis & van der Kamp, 1988; WaterMark Consulting LTD., 2010). Due to this downgradient flow into the Lower Floral formation, the Upper Floral Sands and Gravel at the Northern section of the Zehner aquifer appears to be dry. There is a lot of variation in the subsurface geology within the spatial extent of the Zehner aquifer.