Abstracts

(up to 100m-thick x kms in width & length). The deeply buried Guelph Pinnacles are
not biogenic reefs, but comprise older and variably paleokarsted Lockport Group strata
(Gasport & Goat Island Fms) – similar to high-flow groundwaters discovered in Cambridge-Guelph.
The up to 100m of paleorelief of Lockport Group strata represents an ancient
(Early Silurian) discontinuous, northwesterly facing set of scarps (mesa/butte topography—tower
karst) enveloped by Salina Group shallow marine microbialites/evaporites
(Sarnia area). Newly acquired biostratigraphy data suggest a significant time break separates
Lockport and Salina Group strata. The Guelph Fm is a karst breccia regionally – reflecting
extensive Silurian karst erosion – terrestrial settings (Sarnia area) that transition to
marginal marine-estuarine (Bruce Peninsula-Mount Forest-Kitchener-Waterloo) through
more open marine settings (i.e. Luther Lakes-Elora to Guelph-Cambridge regions) in an
ESE direction – carbonate ramp dipping toward the Appalachian Foreland Basin.
180 - The Use of Mass Balance Modelling to Assess Production
Well Capture Zones
M. Fraser & C. Johnston
Stantec Consulting Ltd., Kitchener, Ontario, Canada
R. Wootton, R. Vaillancourt, & E. Hodgins
Regional Municipality of Waterloo, Kitchener, Ontario, Canada
Source water protection is the first step in the multi-barrier approach to protecting drinking
water. Capture zones are the basis for source water protection and source protection
plans and are used to assess potential threats to water quality and/or quantity. The capture
zones delineate the extent and boundaries of the land area contributing water to the intake
or well. Therefore the reliable determination of these capture zones is crucial to successful
source water protection planning.
For groundwater supplies, capture zones are typically developed using groundwater flow
modelling, which depending on the assumptions and parameters used (or known at the
time) could provide varying results. Mass balance modeling of surficial contaminants, such
as nitrate and chloride, could be used to assess the accuracy of these capture zones. The
premise being that the mass of a parameter applied at surface should equal the mass of
the parameter removed in the pumped water at the production well once degradation and
attenuation are considered.
Real world examples will be presented to demonstrate how mass balance modeling of
nitrate and chloride was used to further refine the understanding of the production well
capture zone.
IAH-CNC 2015 WATERLOO CONFERENCE
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