4. How is an Atlantic RBCA clean up carried out? réponse
When a spill occurs or contamination is discovered, the provincial Department of Environment is advised and an investigation is initiated. No matter how big or small the contamination seems to be, a sequence of basic activities are performed for all human health and ecological risk/exposure assessments, which include:
- a visual site assessment and document review to look for any causes for concern
- identifying chemicals of concern
- identifying possible receptors – adults, children, animals and plants
- identifying pathways that could result in exposure to the chemicals of concern, through air, water, contact with the soil or breathing of dust
- risk and sensitivity/uncertainty quantification, and
- development of a remedial action plan to manage risks
- implementation of the remedial action plan
There are up to six steps involved in an Atlantic RBCA cleanup:
Step 1: Initial Notification
When contamination is discovered, a Department inspector investigates as part of the notification process. The investigation identifies who is responsible for the property, identifies contaminants and includes a preliminary assessment of risk. The Inspector can order immediate, limited clean up action, or the Inspector can advise the property owner to hire a professional to do a more thorough site evaluation.
Step 2: Site Evaluation – Tier 1
A professional trained to use the Atlantic RBCA process evaluates the site for the property owner. Atlantic RBCA includes three tiers of site evaluation. At Tier 1, the sources of contamination transport pathways and exposure pathways are identified.
Using documents or the Atlantic RBCA software, measures of the levels of contaminants on the site are compared to risk-based screening levels (RBSLs) provided in an Atlantic RBCA generic look-up table. If the screening levels are not exceeded and the conditions on the site are not exceptional, no further action may be required.
Step 3: Remedial Action Plan or an Expanded Site Evaluation – Tiers 2 and 3
Where contaminant concentrations on a site are above the screening levels, the site professional prepares a remediation action plan to correct the situation and submits it to the Department of Environment.
An appropriate remedial action plan sometimes requires a Tier 2 evaluation, specific to conditions of the site, to correctly identify the best ways to manage and reduce the risks. This is often true at petroleum release sites. In a Tier 2 evaluation, the site professional collects detailed site data. The site-specific information is entered into the Atlantic RBCA software, which calculates Site-specific Target Levels (SSTLs).
Some sites with complex conditions or contaminants benefit from a more extensive evaluation. This is a Tier 3 approach which goes beyond the Atlantic RBCA software to include detailed site characterization, developm ent of site-specific numerical models and evaluations, and complex fate and transport models.
After the Tier 1, 2 or 3 site evaluation is completed, the site professional develops an appropriate remedial action plan to meet the risk management targets that have been identified and submits it to the Provincial Department of Environment.
Step 4: Review of the Remedial Action Plan
The Provincial Department of Environment reviews each remedial action plan to evaluate if it properly manages identified risks. Remedial action plans may require revisions, including returning to Step 3 to perform a more extensive site evaluation using the next higher Tier.
Once the Department accepts the remedial action plan, clean up work can begin.
Step 5: Remedial Action Plan Implementation
The property owner and site professional implement the remedial action plan to remove contamination, limit exposure pathways and institute controls on how the land is used. Testing after clean-up work is completed will confirms that target levels have been achieved.
Step 6: Compliance Monitoring and Site Maintenance
Once the property owner and site professional are satisfied that the objectives of the remedial action plan are achieved, they submit a Closure Report to the Department of Environment. The report details the final condition of the site, any land-use restrictions and any ongoing monitoring requirements. The Department of Environment acknowledges receipt of the Closure Report and confirms if further actions are required.