What is the difference between silt/clay and sand/gravel in the Tier I Look Up Table?

A coarse grained soil (sand/gravel) is defined as material having greater than 50% (by dry weight) particles equal to or larger than 75 microns (200 mesh) in diameter. Materials with less than 50% sand-sized particles are considered fine-grained soil (silt/clay). If no seive data is available, then the lowest applicable number should apply until a seive test is performed.

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Technical FAQs

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General FAQs

1. What is Risk Based Corrective Action (RBCA)? réponse

RBCA (pronounced « Rebecca ») refers to a new philosophy for managing contaminant release sites. With this new approach, the amount of environmental management required to ensure protection of human health and the environment is based on a scientific assessment of the risks posed by the contaminants, both now and in the future.

Environmental management always considers the risks of contaminants on a site. RBCA also considers the likelihood that people or environmental resources could be harmed by the contaminant. It achieves this by looking at the characteristics of the site, such as the type of soil, the location of water on the site and how the land is likely to be used in coming years.

RBCA clean-up goals are based on reducing risks to low, acceptable levels. This may be achieved by reduction of contaminant concentrations and it may also involve reducing the potential for exposure. An industrial site destined for redevelopment as a playground would require more stringent environmental management than if it were continuing in industrial use, where children do not play and workers protect themselves from exposure to substances.

At some sites it is not possible or practical to remove substances due to technological, physical or financial constraints. The risk-based approach allows the risks associated with leaving substances in place to be estimated. This information is then used to design appropriate risk management solutions to manage contaminants onsite and eliminate risks or reduce them to appropriate levels.

Previously, an industrial site would have to be cleaned to very low, background-level criteria by reducing the amount of contamination present. This would be true even if the land was remaining in industrial use. To confuse matters more, different jurisdictions could set different criteria for the clean up.

RBCA sets the stage for effective and efficient clean-ups. The advantages of using RBCA include that it:

  • Permits rapid response to critical levels of contamination
  • Documents the substances at a site, their location and their extent on- and offsite
  • Estimates the size and likelihood of risks and hazards to human and non-human receptors
  • Documents and evaluates the effectiveness of measures proposed to manage contamination in place
  • Targets cleanup levels are based on current and future use
  • Provides options in appropriate remedial measures
  • Allows property owners to allocate environmental resources more effectively
  • Offers consistency in determining clean-up levels within and between jurisdictions
  • Results in fewer sites being fenced off and abandoned
2. How is « Atlantic RBCA » different from « RBCA »? réponse

Atlantic RBCA is an adaptation of RBCA for conditions in Atlantic Canada. RBCA was developed over a ten-year period in the United States. It includes computer software that helps in the assessment of risks from petroleum products for a typical contaminated site, a common and critical problem all over North America. The RBCA process and training has been standardized by the American Society for Testing and Materials, the American equivalent of the Canadian Standards Association.

Atlantic RBCA, like its predecessor, is both a philosophical approach and an analytical software for petroleum contaminated sites. The Atlantic RBCA software reflects typical soil and groundwater conditions in Atlantic Canada. The software uses the most up-to-date identification of petroleum components and is based on Canadian health standards.

Each province using Atlantic RBCA will establish and maintain their own regulations governing environmental protection, while they promote the RBCA approach to the challenge of restoration of contaminated sites.

3. When we hear about petroleum contamination, what exactly does that mean? réponse

Petroleum products include gasoline and furnace oil. Our society has used these products for almost a century and spills and fuel from leaking storage tanks have contaminated many properties.

Petroleum contamination is a concern because it is persistent in soils, where it moves and degrades very slowly. Spilled petroleum products can seep into streams and dispersing into groundwater reservoirs, seriously degrading water supplies. Petroleum impacted soils release harmful vapours that have the potential for adverse effect to both human health and the environment. when the soil is disturbed.

The effects on human health include everything from minor physical symptoms to life threatening diseases such as cancer. Children are often most at risk from exposure to contaminated soil, air and water.

Petroleum products can also have a serious adverse effect upon the environment. Sites where spills have occurred can release substances that can kill fish, impair the reproduction of birds, and contaminate the food web, resulting in both short term and long term damage to an ecosystem.

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.

5. Who oversees the Atlantic RBCA program? réponse

Partnership is a key element in the success of Atlantic RBCA. A co-operative committee called Atlantic Partners in RBCA Implementation, (or Atlantic PIRI), developed Atlantic RBCA and continues to oversee its implementation across the region. The committee includes representatives from the petroleum industry, environmental consultant companies and government departments from the four Atlantic Provinces.

Atlantic PIRI encompasses the different mandates and objectives of each of the partners. The Provinces have a responsibility to prevent pollution and to regulate the clean up of contaminated sites. The petroleum industry views remediation of sites they own as a corporate necessity. Environmental consultants need to understand how and when to use Atlantic RBCA to serve their clients.

When Atlantic RBCA is applied to remediate a site, there is a working partnership between the property owner, the site professional, and the Provincial Regulator, which ensures environmental protection as well as cost-effective and efficient clean up.

In, addition to these partners, others have an interest in seeing contaminated sites managed effectively. Local governments are concerned about their potential liability when approving developments on contaminated land. Landowners and developers wish to redevelop contaminated sites and avoid long-term liability. Without a process they can have confidence in, bankers are reluctant to lend money for development of contaminated land, fearing they may have to pay for site cleanups if a loan defaults.

6. Does Atlantic RBCA represent an improvement in protecting the environment and human health? réponse

Yes. Atlantic RBCA increases the level of human health and environmental protection because it includes comprehensive analysis of risks that are related to the actual conditions on an individual site. The Atlantic RBCA software includes state-of-the-art analysis of the risks from petroleum products, taking into account the differing hazards associated with the different hydrocarbons. The software also estimates risks associated with other substances, such as the carcinogenic organic chemicals benzene and toluene which are commonly found in gasoline. This analysis produces more stringent clean up requirements when more risk is present.

As the risks are assessed, Atlantic RBCA requires the most protective values be applied. When a substance can present a risk to human health, the environmental management must ensure that health limit is not exceeded. Similarly, if a contaminant presents more risk to the environment than to human health, the environmental protection level will be applied. Even if no health or environmental risk remains, aesthetics such as a lingering odour or taste in water will be sufficient to require further management.

7. Where can I get more information about the program? réponse

You can get more information in many forms:

  • The How Clean is Clean? brochures on this web site provide general information. Copies of the brochures are also available from the offices of the your provincial Department of the Environment.
  • The Atlantic RBCA web site includes general and detailed information, updates and technical documents from all four Atlantic Provinces, available for download.
  • Advanced Atlantic RBCA training sessions, presented by the Atlantic PIRI Committee and the three regional Environmental Industries Alliance organizations, offer site professionals. Information about sessions is available on this web site and from the Provincial Environmental Industry Associations.
  • Contact your Provincial Department responsible for environment.
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