Abstracts

metals and metalloids that may persist for even longer time periods. In order to protect water
quality and manage contaminated sites effectively, the drivers and controls on groundwater
flow and solute transport need to be understood. The purpose of this research project assess
the risk to the environment posed by storage of low level radioactive waste at the Canadian
National Laboratories’ (CNL) Chalk River, Waste Management Area F (WMAF) site.
The larger project includes an investigation of geochemical, vadose zone and saturated zone
processes. The focus is on the potential for transport once solutes reach the water table. This
has yet to happen in appreciable levels at this site. As a result, this study has concentrated on
hydraulic testing and instrumentation of piezometers at WMAF and adjacent areas. During
August 2014, over 20 slug tests were performed at WMAF. Transducers were installed to
measure hydraulic head. Up until this time, hydraulic head measurements were taken sporadically
by CNL staff. Results of the field program have been used to create a probabilistic
groundwater flow model. Results provide a range of travel times between the water table
beneath the waste and the wetland to the east. These travel times provide a framework to
guide future investigations that will reduce the uncertainty and risk.
187 - Assessing the Impacts of Contaminated Groundwater
Discharges to the Surface Waters of the Canadian Great Lakes
Basin: Science Needs and Data Gaps
Brewster Conant Jr.
Department of Earth and Environmental Sciences - University of Waterloo, Ontario,
Canada
A review was undertaken regarding the current state of knowledge with respect to chemical
contaminants in groundwater discharging to the surface waters of the Canadian Great
Lakes Basin (GLB) as part of Canada’s reporting obligations required by the Great Lakes
Water Quality Agreement (GLWQA) Annex 8 regarding groundwater. The purpose of
the work was to identify groundwater impacts on the integrity and quality of the waters of
the Great Lakes, evaluate the risk posed by different types of groundwater contaminants,
and identify information gaps and science needs. Surprisingly little information was found
in the peer review literature or government databases regarding direct discharges of contaminated
or uncontaminated groundwater to the Great Lakes. Additional information
regarding contaminated groundwater discharges may exist in consultant reports submitted
to governmental agencies but they are not publically available. Even if all sources of
contaminated groundwater flowing to surface waters of the GLB were known, determining
how much of the contaminants actually pass through the groundwater-surface water
transition zone and into surface water is problematic. Understanding the role and ecological
importance of transition zones was identified as being a crucial part of evaluating
the actual impact of contaminated groundwater discharges. Transition zones can modify
the composition and concentration of groundwater plumes prior to discharging to surface
water but they also can be where adverse ecological exposures occur because they provide
valuable habitat for benthic and interstitial organisms, areas for fish spawning, and thermal
refuge for aquatic life. Overall, road salt, nutrients, urban contaminants and petroleum
products were of greatest ecological concern because of the large quantities released into
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