Environmental Risk Assessments
The assessment of the risks to human and ecological health is an important component of contaminated sites management. Risks to human health posed by residual contaminants can be evaluated using the risk based corrective action (RBCA) approach, and to this end the Atlantic RBCA methodology has been formally adopted by all four Atlantic provinces.
Contaminated sites plan
The Atlantic RBCA approach is documented by the Atlantic PIRI (Partners in RBCA Implementation) Committee and can be followed using an associated spreadsheet modelling system. It is a tiered approach wherein remediation criteria can be refined depending on the amount of information available. The generic Tier I criteria were developed using conservative assumptions applicable to most sites. At Tier II, site specific information is utilized to provide a more realistic if less conservative assessment. At Tier III, remedial criteria are developed using a large amount of site-specific data to provide a more definitive analysis of environmental risk and the appropriate remediation criteria.
An approach to ecological screening was also developed by the Atlantic PIRI group. The screening involves non-intrusive observation and the results from any Phase II site assessment activity. If potential ecological receptors are considered to be at risk, the site assessment process can be adjusted to ensure that the required ecological data are obtained. It may be that ecological receptors are present but that pathways are incomplete or the point of exposure concentrations are acceptably low.
Should ecological screening identify impacts that can not be otherwise addressed, the associated risks are determined at Tier III. This involves field surveying by qualified biologists, and the comparison of contaminant concentrations with Environment Canada/CCME criteria.
The results of the risk assessments are compared to ensure that selected remediation criteria protect both human health and the broader environment.
