Millennium EMS Solutions Ltd.
May 2017
Project Description (Summary)
The overall objective of this project was to develop distributions for the natural concentration of background metals in shallow Alberta groundwater. The starting point for this project was a database of groundwater samples from environmental site investigational and other activities across the province. Two groups of data screening processes were used to remove data points not related to background conditions. The first group of processes involved steps that could be applied to the dataset as a whole, removing unsuitable data points based on metadata contained in the database, such as location, depth, and concentrations of other chemicals. This group of processes is referred to herein as global screening. Global screening steps removed any samples associated with common contaminants, as well as processes known or suspected to potentially cause metal contamination (e.g. thermal mobilization of metals at SAGD sites). A second group of processes, referred to herein as site-specific screening, examined the highest concentration of each metal in the remaining database, rejecting samples that could not unequivocally be associated with background conditions until a maximum background value could be identified. Maximum background values were determined for 16 out of the 17 metals for which Alberta Tier 1 guidelines are available. A maximum background concentration was not determined for barium since a barium concentration of 1 mg/L was used as a screen to remove groundwater samples assumed to be contaminated with drilling mud.
Additionally, correlations between chloride and trace metal concentrations in the unscreened dataset were investigated to determine if there was a relationship between produced water releases and metal concentrations in shallow groundwater.
Project Outcomes & Tangible Outcomes
# 16-SGRC-05