Dolostone Bedrock Aquifer Capacity Assessment for a Municipal Water
Supply In Southwestern Ontario
Greg Padusenko and John Piersol
Golder Associates Ltd., Cambridge and Mississauga, Ontario, Canada
gpadusenko@golder.com
Colin Baker
The Corporation of the Township of Centre Wellington, Ontario, Canada
Jonathan Munn, Suzanne O’Hara and Beth Parker
The University of Guelph, Ontario, Canada
KEY WORDS
- Bedrock Aquifer Mapping, Hydrostratigraphic Characterization
ABSTRACT
The Township of Centre Wellington is located in Wellington County in southwestern Ontario. The Township owns and
operates the Centre Wellington Drinking Water System which services the communities of Fergus and Elora. Centre
Wellington is typical of many amalgamated rural municipalities in Ontario with a mix of agricultural activities and small
urban centres. The Township relies solely on groundwater, pumped from nine operating wells completed in bedrock
aquifers, for its potable water supply (serviced population of approximately 17,140). To understand the sustainable limits
of its water resource relative to future demand projections, the Township has undertaken a hydrogeological investigation
aimed at characterizing its underlying bedrock hydrostratigraphy on a local and regional scale. The purpose of the
proposed investigation is to assess well field capacities in these small urban centres to determine water supply
susceptibility to contamination and to develop source water protection strategies for existing and new water sources.
The investigation has included the drilling of 3 cored bedrock holes, 3 rotary bedrock holes, downhole geophysical
logging, flow profiling, FLUTe transmissivity profiling, high resolution active line source (ALS) temperature logging for
discrete flow features and the installation of multi-level monitoring well nests in the vicinity of Fergus and Elora. Through
on-going collection of data from these monitoring locations, a high-resolution spatial and temporal data set has been
developed from which steady-state and transient groundwater response analyses could be undertaken. These analyses
include comparisons of groundwater potentials in shallow and deep groundwater flow systems and groundwater level
response to shut-down and pumping of municipal wells. The use of these methods to evaluate the hydraulic
characteristics of the aquifer and provide better three-dimensional mapping of flow zones and hydrogeologic units
including aquitards will assist the Township in implementing measures to protect its existing municipal groundwater
supply and allow it to undertake exploration for new supplies with a higher level of confidence.