Phase I and II ESAs, and Indoor Air Quality Sampling at Multi-Tenant Medical Building

XCG was retained to complete a Phase I Environmental Site Assessment (ESA) to secure financing for a multi-tenant medical building in the Edmonton, Alberta (subject property or site). 

Based on the findings of the Phase I ESA, two potential sources of significant contamination were identified associated with the historical site operations at adjacent properties, including two former gasoline service stations and two former underground storage tanks (USTs), which had historical records of leaks, up-gradient of the subject site. To further investigate and qualify on-site soil and/or groundwater impacts, if any, associated with the potential sources of significant contamination identified by XCG during the Phase I ESA, XCG completed at Phase II ESA on the subject property. The Phase II ESA included the advancement of six boreholes completed as monitoring wells to facilitate the collection of soil and groundwater samples for laboratory analyses of petroleum hydrocarbon compounds (PHCs) (Fractions F1 to F4), volatile organic compounds (VOCs), and lead. The Phase II ESA investigation found no soil impacts were present at the subject property; however, groundwater VOC impacts were present in two monitoring wells sampled during the investigation. 

Based on discussions with the property owner, XCG developed an understanding of their environmental and business risk tolerance and their key concerns, which related to the potential impacts to the on-site indoor air quality. Taking into the account the site setting as well as the current and future use of the site, XCG determined that the most appropriate and cost-effective way to assess the risk to the building occupants was to conduct indoor air quality (IAQ) monitoring. The sample locations were chosen to represent areas where the potential for vapour intrusion to the basement was highest (i.e. closest to the locations of the highest concentrations of VOCs in groundwater found during the Phase II ESA investigation). The IAQ monitoring results in the locations tested were below the applicable Air Concentration Criteria for commercial occupancy based on the Alberta Environment and Ontario Ministry of the Environment Toxicity Reference Values. 

Outcome: By understanding the drivers behind the deal, and the stakeholders risk tolerance, XCG was able to facilitate completion of the lending transaction with no delay (all work was completed two weeks before closing) and at a cost that was significantly lower than the cost associated with contaminant delineation and on-going groundwater monitoring.