August 2024
Executive Summary
As part of the environmental regulatory framework to minimize risk to receptors, chemical parameter concentrations in soil or water exceeding regulatory guidelines, which can be attributed to industrial activities at the site, require remediation and/or monitoring. This is complicated by the fact that various parameters are naturally elevated in Alberta, with concentrations that exceed the generic (Tier 1) Soil and Groundwater Remediation guidelines. Where this occurs, environmental professionals must prove to the satisfaction of the applicable regulatory body that the elevated concentrations are of natural origin and not the result of industrial activities to avoid unnecessary remediation activities. This challenge is faced in environmental management of industrial sites while active and at end of life, and when responding to unintentional releases during product handling or transportation.
Salinity and certain metals are the most common naturally elevated parameters in Alberta. If salt and metal parameters are naturally elevated compared with Tier 1 guidelines, environmental professionals can mistake these naturally elevated concentrations for contamination, followed by unnecessary monitoring and remediation efforts. The challenge of proving, where applicable, that elevated parameter concentrations are of natural origin, has been identified by industry and practitioners as a root cause of cost uncertainty, multi-year timelines, reaching regulatory closure, and in some cases, requirements for unnecessary and unsustainable monitoring and remediation efforts.
Industry, government, and environmental consultants have identified a need for more effective identification of background salt and metals concentrations. There is currently no publicly available resource that maps or predicts background concentrations of these parameters for Alberta. The Alberta Background Soil Quality System (ABSQS) project was initiated by InnoTech Alberta (InnoTech), the Alberta Upstream Petroleum Research Fund (AUPRF) managed by the Petroleum Technology Alliance of Canada (PTAC), and the Clean Resources Innovation Network (CRIN) to address this gap. The overall objective of the ABSQS is to develop a database of background metals and salinity parameters in Alberta to decrease the cost and time required to identify and remediate contaminated sites. The ABSQS is intended to be used as a resource to assist industry and government in environmental management of sites that are actually contaminated.
The soil quality parameters (salinity and metals) analysis workflow derived to identify background data records provided stable and replicable results. Based on background metals fingerprints identified in the cleaned dataset, 18,513 data records of the 23,224 salinity data records in the master dataset were identified as being representative of background. The predictive soil mapping accuracy was greater for subsoil predictions compared to topsoil and all subsequent polygons were created using the subsoil prediction results due to the higher accuracy. Only a small percentage of the polygons had soil observation data present within the polygon, with approximately 5% of polygons having direct salinity data, and 2% having metals data. Therefore, most polygons had data extrapolated from the polygons with observations data based on the distribution of probabilities for the electrical conductivity (EC) and sodium adsorption ratio (SAR) class predictions. Prediction certainty was inversely related to salinity, with areas of higher salinity having more uncertainty.
The next phase in this project will be to execute a field sampling program to fill in the data gaps identified during this phase of the project, and to complete further testing and validation of the model.
23-RRRC-02