Client: Confidential
 Location:  North GTA, ON

XCG was retained by the legal counsel for the property owner to complete indoor air sampling in residential basements in two private homes. This work, which was completed in conjunction with groundwater and soil vapour sampling, was ordered by the Ontario Ministry of the Environment and Climate Change (MOECC). The purpose of the investigation was to collect information and data needed to assess the risk to human health related to migration of tetrachloroethylene (PCE) and associated degradation products in groundwater and soil vapour down-gradient from a nearby dry cleaning facility.

XCG completed the field activities and the reporting in accordance with XCG’s Standard Operating Procedures (SOPs), and the MOECC sampling protocols.

Pre-sampling inspections were conducted in the basements of the residential properties to assess potential sampling locations, preferential pathways, the presence of chemicals or household products which could interfere with the analytes in questions, etc. It was imperative that XCG personnel were sensitive to the privacy and the schedules of the occupants, and that any questions were respectfully answered in advance or in person. The pre-sampling inspection and the indoor air sampling required coordination between multiple parties, including XCG personnel, the property owners, the property tenants and the legal counsel.

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All chemical analyses were performed in accordance with O. Reg. 153/04, and specifically the related document entitled “Protocol for Analytical Methods Used in the Assessment of Properties under Part XV.1 of the Environmental Protection Act, March 2004 (amended as July 1, 2011).

The soil vapour results were compared to calculated Soil Vapour Screening Criteria derived by XCG personnel using the MOECC Modified Generic Risk Assessment (MGRA) Model. Indoor air quality data were assessed based on the MOECC Health Based Residential Indoor Air Criteria.

OUTCOME: Although groundwater and soil vapour impacts were present downgradient of the dry cleaning operation, XCG was successful in proving to the MOECC that the elevated concentrations of PCE and it’s degradation products in groundwater did not result in adverse impacts to the residential indoor air quality/human health based on the calculated Acceptable Soil Vapour Screening Criteria. As a result, no additional monitoring or clean-up orders were issued provided that vapour sampling continue on a regular basis.