Trichloroethene (TCE) sinks in water and was widely used historically as an industrial solvent and metal degreaser. Concerns about its carcinogenicity, toxicity, and effects on the environment have led to its replacement with safer alternatives.
A global manufacturing company engaged Golder to investigate TCE contamination at a large operational facility under environmental audit. The client had historically used TCE as a solvent for degreasing and it had been detected in groundwater close to the site boundary. TCE is no longer used at the facility and none remains onsite to be a continuing source. However, the source of these groundwater impacts had not been identified with confidence despite years of investigation.
Golder’s air quality team, working from our National Association of Testing Authorities, Australia (NATA)-accredited Air Quality and Odour Laboratory in Melbourne, designed a passive soil vapour monitoring program to be applied at the client’s site. The team recommended passive soil vapour sampling because it offers a lower-cost, rapid assessment technique to identify and prioritise sources of TCE contamination in shallow soil.
The program assessed the lateral distribution of TCE in soil vapour close to known source areas, and targeted locations near occupied buildings where there may have been potential for vapour intrusion to indoor office spaces. Over two months, the team deployed 150 samplers across the site and integrated the results to prepare a series of concentration heat maps.
The passive soil vapour sampling indicated that the distribution of TCE in soil vapour differed from the distribution in groundwater, with concentration hot spots more localised in some areas and extending more broadly in others. It also revealed the presence of potential source areas that had not been identified from the groundwater data.
The Golder team integrated the soil vapour results to provide a level of understanding of on-site TCE that would not have been achieved by other methods of soil sampling and groundwater investigation, enabling our client to make informed decisions.
Golder’s application of reliable, efficient, and cost-effective passive soil vapour sampling enabled our client to prioritise the multiple potential source areas across the site and to target further groundwater investigation in a rapid and cost-effective manner.