Geosyntec’s Todd McAlary, PhD, PEng, PG, and Ainsley Inglis, PEng, and SiREM’s Brent Pautler, PhD, coauthored “Proof-of-Concept Testing of Passive Sampling of Sewer Gas for VOC Vapors Using the Waterloo Membrane Sampler.”

Published by Green Analytical Chemistry, the article is available now online and will be published in the December 2025, Volume 15 issue. Their other coauthor is Heidi Hayes of Eurofins.

Todd is a Senior Consultant based in Ontario with over 30 years of experience evaluating contaminant fate and transport in soil and groundwater. He specializes in assessing and mitigating the migration of volatile organic compound (VOC) vapor from the subsurface into buildings and in assessing human health risks associated with inhalation exposure.

Ainsley is a Project Engineer based in Ontario with experience in vapor intrusion investigation and mitigation, risk assessment, and in situ remediation technologies. She focuses on groundwater and soil remediation, as well as mitigation system design, implementation, and testing.

Brent is the Chemistry Services Manager at SiREM in Ontario. He brings more than 10 years of experience in spectroscopy, chromatography, mass spectrometry, passive sampling, and chemistry informatics. Throughout his career, Brent has worked with scientists, engineers, and consultants to help solve unique problems in the laboratory and the field.

Green Analytical Chemistry promotes validated, eco-friendly analytical methods that minimize hazardous chemicals and waste, support onsite remediation, and balance sustainability with practical performance and regulatory standards.

Abstract: Proof-of-Concept Testing of Passive Sampling of Sewer Gas for VOC Vapors Using the Waterloo Membrane Sampler

Sewer gas ingress to houses has recently been identified as a pathway of potential human health concern for volatile organic compounds (VOCs) such as chlorinated solvents and petroleum hydrocarbons at or near regulated contaminated sites. This is a relatively new field of assessment and raises questions regarding monitoring methods. This article provides data to compare a passive sampling alternative to active grab samples for sewer headspace VOC vapor monitoring. Passive sampling has several potential advantages, including fewer sampling events needed compared to active grab sampling for confident assessment of time-weighted average (TWA) concentrations, reducing the carbon footprint. The Waterloo Membrane Sampler™ (WMS) has a hydrophobic membrane to limit interference attributable to water vapor and small size to enable deployment through holes in maintenance covers without lifting the cover. This paper describes a proof-of-concept field trial conducted in three events. The WMS results show good precision and reproducibility and reasonable accuracy, considering temporal variability throughout the sampling period was not explicitly determined. Furthermore, collection of longer-duration TWA samples has less susceptibility to bias from temporal variability compared to active grab samples. The WMS data showed much lower reporting limits than the TO-15 full scan analysis and quantified several compounds that were not detected by the TO-15 full scan analysis. The WMS also showed good durability over extended sample durations in a humid environment, with no special considerations for security, ease of use, shipping, storage and handling, and comparable cost to the active sampling method.

More Information on Passive Sampling and VOCs

Read the article.
Learn more about the journal.
For more information on vapor intrusion assessment and remediation, contact Todd at TMcAlary@Geosyntec.com.
Learn more about Todd: Todd McAlary
Learn more about Ainsley: Ainsley Inglis
Learn more about Brent: Brent Pautler