Abstracts

York Region has also begun projects that will permit Region use of the Tier 3 model for
updates to York Region capture zones (Well Head Protection Areas). The work includes,
sensitivity assessments, model updates, and assessment of hydrogeologic assumptions used
in earlier capture zone delineation projects. In addition to implementing Source Protection
Plan policies, York Region developed an operational plan to redistribute water taking and
mitigate predicted impacts of extreme drought (climate change).
The Tier 3 models have provided York Region and its partners, insight into the municipal
supply aquifers. They have highlighted potential water management issues and provided
collaboration opportunities between water managers and planning authorities. Continued
application of the York Region Tier 3 models, as a result of SWP policies, will improve the
models and improve the understanding of local groundwater resources.
183 - Development of a Risk Reduction Process to address
Groundwater Safety in Northern Canada
N.S. Sundaram, J. Sauriol & J.P. Gobeil
Stantec Consulting Ltd., Ottawa, Ontario, Canada
A drinking water system that obtains water from a groundwater source may not require
secondary disinfection, particle filtration, removal of dissolved organics, and other water
treatment techniques, as the aquifer supplying the water may be able to provide sufficient
natural filtration. Because of the significant human health issues associated with drinking
water supply potability, development of a risk reduction process to evaluate aquifer safety
is required. The standard risk reduction process involves the installation of test wells in the
supply aquifer and observation wells between the test wells and nearby surface water bodies,
based on published information from the provincial ministries with respect to aquifer geometry,
geology, and hydrology. The application of this standard process to some northern
Canadian environments introduces significant scientific uncertainties, owing to the lack of
published information at a scale suitable for the application of standard practice, and to the
potential presence of discontinuous groundwater flow regimes resulting from northern geology
and/or significant frost/permafrost presence. Therefore, development of an improved
risk reduction process to address groundwater safety in Northern Canada was considered.
Our approach to the development of an improved risk reduction process comprised of
integrating multiple independent lines of evidence to arrive at a defensible conclusion. In
order for our approach to show potential, at least two lines of evidence needed to confirm
each other. A highly defensible approach would require confirmation from all three lines
of evidence. We have applied this altered risk reduction process to a site located within
the vicinity of Val-d’Or, Quebec. For the subject site discussed in this paper, we have
applied a multi-pronged approach that comprised of assessing several independent lines of
evidence simultaneously (i.e., application of environmental tracer chemicals [Chlorofluorocarbons
(CFCs), Sulfur Hexafluoride] to groundwater age, identification of microscopic
surface water-borne organisms to determine surface water intrusion, and hydraulic testing
to determine aquifer properties) to overcome the uncertainties that are unique to Northern
Canadian environment.
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