GeoPro Talks – A Case Study – Forensic Analysis to Characterize an Unknown Source of Methane in Soil Vapour

October 14th, 2022 by

The presence of methane at contaminated sites can originate from multiple sources including thermogenic (i.e., natural gas seeps and distribution leaks) and biogenic (i.e., municipal landfills, sewer gas, natural organic materials, and residual petroleum hydrocarbons). Understanding the source(s) of methane is critical towards the development of corrective action strategies for vapour intrusion. A case study is presented where the source of an unforeseen methane soil vapour  plume with concentrations of up to 70 percent by volume (%vol) was identified. Using innovative forensic methods, including but not limited to: i) radiocarbon dating, ii) ratio analysis of light hydrocarbon fractions (C2-C6+) to methane, and iii) analysis of mercaptans, I reveal the puzzling source of methane.

October 2022