Assessing Groundwater Supply Sustainability in the Multi-Layer Aquifer
System of the Waterloo Moraine
Stephen Di Biase, Jen Hancox, John Petrie, George Schneider
Golder Associates Ltd., Mississauga, Ontario, Canada
Amy Domaratzki
The Regional Municipality of Waterloo, Ontario, Canada
THEME -
Hydrogeological, Regional Aquifer Characterization
ABSTRACT
The Region of Waterloo, with a population exceeding 500,000, is the largest municipality in Canada that is dependent on
groundwater for its water supply. Within the core urban area of the Region, approximately 100 groundwater production
wells are operated, providing a firm capacity of approximately 45 million imperial gallons per day. The water source for
many of these production wells are the overburden aquifers associated with the Waterloo Moraine, an interlobate
moraine formed by the convergence of four glacial lobes. Due to successive advances and retreats of the ice lobes, the
overburden stratigraphy within the Waterloo Moraine represents a complex depositional sequence. Within the City of
Waterloo, moraine deposits generally reflect four interstadial granular deposits (aquifers), separated by five glacial till
deposits (aquitards). The thickness, continuity and hydraulic properties of these soil deposits are highly variable. As a
result, extensive studies have been undertaken to understand the glacial history and conceptual geological model of the
area.
The Region has recently completed a hydrogeological investigation to assess the sustainability of groundwater pumping
from three new municipal test wells completed in intermediate and deep aquifers located in the northwestern portion of
the City of Waterloo. This area is located on the eastern flank of the moraine and includes environmentally sensitive
lands, water features and habitat. Key components of the hydrogeological investigation included flow monitoring in local
surface water courses, an assessment of aquatic habitat and a 42-day groundwater pumping test. To assess the
individual and cumulative effect of pumping from the three municipal test wells, the pumping test was structured with
staged start-up and shut-down of the municipal test wells. The effects of groundwater pumping were monitored at a total
of 136 locations, including 39 municipal monitoring well nests, 7 stream flow stations, 6 wetland piezometers and 26
private wells.
The structure of the pumping test and comprehensive monitoring program allowed for an improved understanding
regarding the lateral extent, transmissivity and confined condition of two water supply aquifers, as well as the vertical
hydraulic conductivity of a regionally extensive aquitard. The Environmental Assessment process concluded that
sustainable groundwater supply would be possible from two of the three municipal test wells. This presentation will
review the interpretation of the field study results, the conclusions of the hydrogeological study and rationale for
establishing sustainable groundwater supply sources.