In 2015, an environmental consultant completed a Phase II ESA, at a multi-tenant commercial shopping centre in Edmonton. Historical on-site tenants included a dry cleaning facility, which was operated from 1978 to the late 1990s, in the current location of a large (national chain) grocery store. The Phase II ESA identified the presence of PCE and TCE in soil (groundwater was not impacted) beneath the grocery store slightly above Alberta Tier 1 Guidelines. Based on these findings, the consultant recommended completing remedial activities based on an in-situ chemical oxidation (ISCO).
In early 2016, the owner of the site retained XCG to complete a peer review of the 2015 Phase II ESA, and to determine the best course of action. Based on available information and data, XCG determined that the proposed remedial approach would have cost tens of thousands of dollars, take months to complete, and given the low permeability of the impacted soil (clay), would have very limited effect in restoring the on-site soil quality.
Based on the discussions with the stakeholders, XCG developed an understanding of their environmental and business risk tolerance and their key concerns, which related to any restrictions on the continued use of the subject site for the commercial (shopping mall) purposes.
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Subsequently, XCG completed an additional site investigation and determined that the PCE and TCE-related impacts were limited to a localized area beneath the store and the adjacent laneway. Given XCG’s understanding of the stakeholder’s environmental and business risk tolerance, XCG determined that the most appropriate way to assess the soil quality would be by using the Alberta Tier 2 Guideline criteria for PCE and TCE developed for the protection of human health through vapour inhalation, rather than the Alberta Tier 1 Guidelines. This is because the Alberta Tier 1 Guideline criteria for PCE and TCE were developed to be protective of freshwater aquatic life and domestic use aquifer, respectively, i.e. exposure pathways not associated with the subject site.
By using the Alberta Tier 2 Guideline criteria for PCE and TCE which were applicable to the subject site, XCG determined that the presence of the elevated PCE and TCE concentrations do not represent a significant human health concern to the adjacent residential property and will not affect ongoing use of the subject site for ongoing commercial purposes. Therefore, there is no need for prolonged and expensive remedial activities.
By taking the time to understand the stakeholders’ concerns and their respective environmental and business risk tolerance, XCG was able to generate the necessary information and data required by all parties to make informed business decisions.