Update on soil vapour testing on Menzie, Audrey, Lawrence and laneway

June 25, 2020 – This notice provides an update on the findings of the additional soil vapour investigation completed on Menzie, Audrey and Lawrence Avenues and the laneway in April 2020.

The process

The Ontario Ministry of Environment, Conservation and Parks (MECP) requested the City collect an additional round of soil vapour samples from the same locations that were sampled in November 2019. As such, the City’s consultant, Geosyntec, collected soil vapour samples at the same 15 existing sampling probes located in Menzie Avenue, Audrey Avenue, Lawrence Avenue, and a laneway between Lawrence Avenue and Victoria Road South between April 6 and 8. The samples were collected within the City’s right of way; not on private property. The purpose of this investigation was to evaluate the seasonal variability in the concentrations of chlorinated volatile organic compounds (CVOCs) in soil vapour previously identified in the area and to support the indoor air quality monitoring to be led by the MECP in the future.

The results

The results of the April 2020 investigation indicate that 12 of 15 soil vapour sampling locations showed the presence of trichloroethylene (TCE). This is the same number as observed in November 2019. Similar to November 2019, a location along the laneway between Lawrence Avenue and Victoria Road South also showed the presence of tetrachloroethylene (PCE) in soil vapour. All detectable concentrations of CVOCs in the April 2020 soil vapour samples were lower than the concentrations noted in November 2019. These findings have been reviewed with the MECP.

Both PCE and TCE are industrial solvent used to remove grease from metal parts (also know as degreasers). PCE is also a common dry cleaning solvent. Both can be found in some consumer products, including adhesives, paint and stain removers, and parts cleaners.

Read the Supplemental soil vapour investigation report (June 2020).

Indoor air sampling

Due to current COVID-19 pandemic and the imposed social distancing requirements, the MECP temporarily postponed the residential indoor air-monitoring program along Lawrence Avenue. MECP notified the affected residents of the delay.

Updated October 20, 2020 – The Ministry of the Environment, Conservation and Parks (MECP) completed the voluntary indoor air quality monitoring in select homes on Lawrence Avenue and will be offering additional confirmatory sampling to these same homes in the coming months.


Initial soil vapour sampling was completed last fall. Analysis of the samples found elevated levels of trichloroethylene in some areas. These results were shared with the MECP who reviewed the data and determined that the risk of vapour intrusion into homes was low. Wellington-Dufferin-Guelph Public Health has been kept informed throughout this process.

For more information

Prasoon Adhikari, Environmental Engineer
Engineering and Transportation Services
City of Guelph
519-822-1260 extension 2946
Mobile 519-222-4308
[email protected]