Sam Ziemann From - Region of Waterloo

HYDROGEOLOGICAL ASSESSMENTSTRANGE STREET WATER SUPPLY CLASS EA UPDATEREGIONAL MUNICIPALITY OF WATERLOOBackground ReviewMarch 19, 2012conceptual cross section of the Waterloo Moraine is presented on Figure 3. Numerousadvances and retreats of these ice lobes during the Wisconsin glaciation have resulted in acomplex deposit of ice-contact and glacial outwash sands and gravels separated by silt- andclay-rich tills. Along the flanks of the Moraine, meltwaters resulting from the retreat of glacial iceeroded and cut through the various till and sand and gravel units. The resulting glaciofluvialsediments are typically stratified and sorted to varying degrees.Previous interpretations of the geology and resulting hydrostratigraphy of the Waterloo Morainerelied mainly on the correlation of individual till units across the moraine (Karrow, 1993). Thiswas generally found to be a reasonable approach in the core areas of the moraine where sheetlike till units exist; however, it did not provide a detailed understanding of the sand and gravelunits that were previously mapped as ice-contact stratified drift. In 2002, the Ontario GeologicalSurvey (OGS) embarked on a three year project to produce 3-dimensional mapping of thesurficial deposits within the Region. The methodology and interpretation of the surficial depositsare detailed in Bajc and Shirota (2007).Karrow (1993) referred to the first till units deposited in the area as the Pre-Catfish Creek Tills.These till units are interpreted to be mid- to early-Wisconsinan in age and include the CanningTill and several other unnamed tills. The Canning Till is one of the more continuous andrecognizable Pre-Catfish Creek Tills, although this till is not encountered at all locations withinthe Moraine. The Canning Till is described by Karrow (1993) at its type section near Canningas a nearly pebble-free, purplish, silty clay or clayey silt till. The unnamed Pre-Catfish Tillswithin the Study Area are generally hard, stony silt to clayey silt tills, similar in appearance to theCatfish Creek Till.The Catfish Creek Till is the next till sheet deposited by a major glacial advance from the northto northeast that covered all of southern Ontario. As a result, the Catfish Creek Till isinterpreted to be the first major stratigraphic marker throughout the Waterloo Moraine. TheCatfish Creek Till is an extremely dense, stony, sandy silt to silt till and is commonly referred toas “hardpan” by many water well drillers.One of the most important till units throughout the Waterloo Moraine is the Maryhill Till. TheMaryhill Till is a dense, dark brown, clayey silt to silty clay till and represents the main aquitardunit that protects the deeper aquifer systems utilized by a number of municipal well fields,including the Greenbrook Well Field. Karrow (1993) has interpreted the Maryhill Till asover-riding the sands of the Waterloo Moraine; however, this interpretation has been refined byPaloschi (1993) and more recently by the work of Bajc and Shirota (2007), which have identifiedthree separate ice advances that have resulted in an Upper, Middle, and Lower Maryhill Tillwithin the core area of the Waterloo Moraine.The next two tills deposited after the Maryhill Till within the general Study Area are the Tavistockand Port Stanley Tills. The Tavistock Till was deposited by ice advances from the2.2 hls v:\01609\active\161110897_strange_st\planning\report\final hydrogeo assessment\final\fnl_rpt_120319.docx