Alberta’s contaminated sites policy framework provides three management options:
The Tier 1 and Tier 2 guidelines are equally protective of human health and ecological systems; however, Tier 2 guidelines require a higher degree of site characterization and may be more restrictive than Tier 1 guidelines when a site has characteristics that are more sensitive than Tier 1 assumptions.
In order to comply with the Remediation Regulation a company must complete remediation or assess the risk that a substance release may cause an adverse effect by applying Tier 1 or Tier 2 guidelines. If risk of an adverse effect is found and the company cannot remediate the site within 2 years a remediation action plan (RAP) must be submitted to the AER that identifies how the risk will be managed and when remedial measures will no longer be necessary.
Site Specific Risk Assessment (SSRA)
The development of Tier 2 guidelines is considered SSRA when major changes to parameters or models are needed to develop Site-Specific Remediation Objectives (SSROs). A SSRA may be conducted based on pre-remediation contaminant concentrations or post-remediation (residual) contaminant concentrations to determine whether risks are acceptable or if further remediation or risk management is required.
SSRA’s can range in complexity from a Screening Level Risk Assessment (SLRA) to a Detailed Quantitative Risk Assessment (DQRA):
SLRA – uses default parameters, maximum contaminant concentrations and conservative assumptions related to contaminant exposure and transport, including the use of simple exposure models.
DQRA – requires additional data collection and refinement of conservative assumptions, input parameters and modelling.
For any level of complexity, defensible conclusions must be drawn with respect to risk and the development of SSROs. Additionally, the following is required regardless of site complexity:
How Can This Help Your Site?
SSRA whether simple or complex frequently results in less restrictive guidelines, often reducing the requirement for remediation while still providing adequate protection of relevant human and ecological receptors. This is why industry is trending towards a risk assessment approach and away from Tier 1. SSRA can help a company comply with the remediation regulation by assessing the actual risk from a substance release and defining Tier 2 SSROs, allowing a comprehensive RAP to be developed. Further, regulatory site closure (or a reclamation certificate for upstream sites) through SSRA is possible if the results of the SSRA don’t require restrictions on land use activities and do not require on-going risk management. Depending on the level of complexity, regulatory interaction may be required throughout the SSRA process.
Last but certainly not least, SSRA can reduce the environmental footprint of a site compared to typical remediation practices as it generally reduces the remediation volume – thereby minimizing transport, landfill, and/or onsite mechanical remediation of soil – that also lowers potential emissions from equipment, trucks etc. and might be good for your company’s ESG!
Overview of Site Specific Risk Assessment
If No Risk Identified SSRA Stops Here. Can be demonstrated by:
IF RISK IS IDENTIFIED:
Thanks for reading,
SSRA – site specific risk assessment
COPC – contaminant of potential concern
TRV – toxicological reference value
SSRO – site specific remediation objective