Abstracts

It was estimated that between 50% and 80% of the salt applied in the WHPAs was applied
on the roads with the remainder applied to parking lots. The inclusion of the loading from
parking lots resulted in the estimation of the portion of salt applied to the surface that
infiltrates being about one half of previous estimates completed considering only the salt
applied to roads.
The model was calibrated to historical data and used to predict salt concentrations in the
supply wells using current application rates of road salt. The concentrations of sodium and
chloride in two of the well fields are predicted to continue to meet the drinking water objectives.
Reduction in salt loadings of 25% and 40% are required to achieve drinking water
objectives in the other two well fields.
121 - Salt Assessment of a Low Demand, Rural Well Field IAH-CNC
2015 Waterloo Conference
M.J. Fraser, R. Byer-Coward & R. Freymond
Stantec Consulting Ltd., Kitchener, Ontario, Canada
R. Vaillancourt & E. Hodgins
Regional Municipality of Waterloo, Kitchener, Ontario, Canada
The Regional Municipality of Waterloo (RMOW) was alerted by elevated chloride concentrations
at one of their rural well fields and recognized that work was required to evaluate
potential sources and future chloride trends. The source of chloride was not as clearly
understood as in the urban environment where road salt is generally the primary contributor.
The rural well field supplied a small community where waste water was treated using
residential septic systems. The water supplied by the bedrock aquifer was hard, meaning
many residents were using water softeners. In addition, supply from this well field was minor,
about 14,000 m 3 /year, resulting in a limited well field capture zone. The low pumping
rate and small capture zone meant that a relatively small amount of salt could result in
increased concentrations of chloride at the production wells.
A salt assessment was undertaken to assess the current extent of chloride within the aquifer
system, evaluate future trends in chloride concentrations, and evaluate potential BMPs
and/or well field operation and monitoring strategies with the objective of reducing chloride
concentrations at the wells. Preliminary calculations indicated that chloride loading
from water softeners and road salt may both be significant sources of chloride at the production
wells.
IAH-CNC 2015 WATERLOO CONFERENCE
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