Sub-Slab Vapor & Indoor Air Monitoring
The Tennessee Department of Environment and Conservation (TDEC) had concerns about the potential for subsurface contamination associated with prior uses of a warehouse facility owned by one of Tioga’s clients. Of additional concern was the use of the upgradient adjoining properties. The potential contamination could have allowed gases to infiltrate the building through vapor intrusion pathways such as utility locations. TDEC recommended vapor intrusion sampling.
Tioga prepared a Vapor Intrusion Work Plan outlining the site background, setting and details of the proposed vapor intrusion assessment, as well as a Health and Safety Plan including job hazard analyses for the project. Once approved, Tioga implemented the work plan on a very tight schedule.
The vapor intrusion sampling included:
- Coordinating utility locating services throughout the building,
- Using a rotary hammer drill to access the desired depth below the building foundation,
- Installing semi-permanent soil gas sampling probes,
- Collecting an active soil gas sample from each location,
- Submitting samples and QA/QC samples to an analytical laboratory, and
- Preparing a vapor intrusion assessment report documenting sample locations, sampling procedures, findings and recommendations.
Tioga has continued to work with TDEC to perform a total of four sampling events. Three of the events included obtaining indoor ambient air samples for comparison to sub-slab vapor concentrations. Ultimately, no correlation between indoor ambient air and concurrent sub-slab vapor contamination was identified. The most recent sampling event will likely close out the investigation.