Sam Ziemann From - Region of Waterloo

HYDROGEOLOGICAL ASSESSMENTSTRANGE STREET WATER SUPPLY CLASS EA UPDATEREGIONAL MUNICIPALITY OF WATERLOOBackground ReviewMarch 19, 2012Huron-Georgian Bay ice lobes and is mainly restricted to the western flanks of the WaterlooMoraine. The Tavistock Till is a dark brown clayey silt till, similar in composition to the MaryhillTill, and may correspond to the isolated till units capping the Waterloo Moraine that are referredto by Karrow (1993) as the Maryhill Till. If this is the case, then the Tavistock Till may havebeen deposited within the Study Area along the eastern flank of the Moraine. The Port StanleyTill is similar in age to the Tavistock Till and was deposited by ice advancing from theErie-Ontario ice lobe and is mainly restricted to the eastern flanks of the Waterloo Morainewhich includes the study area. The Port Stanley Till is a sandy silt to silty sand till and isoccasionally stony.Figure 2 presents the surficial Quaternary geology for the general Study Area based oncompiled mapping by OGS (2003). The surficial geology within the Study Area consists ofpredominantly glaciofluvial sandy and gravelly deposits with occasional pockets of stone-poor,sandy silt to silty sand till and clay to silt textured till. Along the major surface water bodiesincluding the Grand River, Strasburg Creek and Schneider Creek, modern day alluvial depositshave been identified at surface (Figure 2).The Paleozoic bedrock geology beneath the Study Area consists of the Salina and GuelphFormations. The Salina Formation consists of interbedded brown dolostone and grey to greenshale with lenses of gypsum and anhydrite. Typically, groundwater extracted from the SalinaFormation within the Region is of poor quality due to high concentrations of calcium andsulphate resulting from the dissolution of gypsum and anhydrite minerals. The GuelphFormation is a cream-coloured crystalline dolostone and represents an important supply aquiferto the northeast in the area of Guelph, and to the east in the City of Cambridge. The contactbetween the Salina and Guelph Formations is interpreted to be slightly west of the Study Area.2.3.1 HydrostratigraphyA comprehensive review of the geology and hydrogeology of the Waterloo Moraine wasundertaken as part of the Study of the Hydrogeology of the Waterloo Moraine in 1995(Terraqua, 1995). As part of this work, a conceptual hydrogeologic model for the moraine wasdeveloped, consisting of three overburden aquifers (Aquifers 1, 2, 3), separated by fouraquitards (Aquitards 1, 2, 3, 4). The upper portion of the bedrock aquifer in the area wasclassified as the fourth aquifer unit (Aquifer 4).Recent work by Bajc and Shirota (2007) resulted in a conceptual geological model for theRegion that consists of an aquifer/aquitard sequence with 19 layers. Many of these layers arefound only locally. Nine layers were identified to be the most regionally significant, andgenerally correspond with those presented by Terraqua (1995). In the naming convention usedby Bajc and Shirota (2007) aquitard units are identified with AT followed by a letter and number(e.g., ATB1), whereas aquifers are identified with AF followed by a letter and number(e.g., AFB1).hls v:\01609\active\161110897_strange_st\planning\report\final hydrogeo assessment\final\fnl_rpt_120319.docx 2.3