Evidence of a sewer vapor transport pathway at the USEPA vapor intrusion research duplex

• Published in: The Science of the total environment Vol. 598; pp. 772 - 779
• Main Authors: McHugh, Thomas, Beckley, Lila, Sullivan, Terry, Lutes, Chris, Truesdale, Robert, Uppencamp, Rob, Cosky, Brian, Zimmerman, John, Schumacher, Brian
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15.11.2017; Elsevier
• Subjects: ENVIRONMENTAL SCIENCES; Indianapolis; Preferential pathway; Utility tunnel; Preferential pathway; Utility tunnel; Indianapolis
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2017.04.135

The role of sewer lines as preferential pathways for vapor intrusion is poorly understood. Although the importance of sewer lines for volatile organic compound (VOC) transport has been documented at a small number of sites with vapor intrusion, sewer lines are not routinely sampled during most vapor intrusion investigations. We have used a tracer study and VOC concentration measurements to evaluate the role of the combined sanitary/storm sewer line in VOC transport at the USEPA vapor intrusion research duplex in Indianapolis, Indiana. The results from the tracer study demonstrated gas migration from the sewer main line into the duplex. The migration pathway appears to be complex and may include leakage from the sewer lateral at a location below the building foundation. Vapor samples collected from the sewer line demonstrated the presence of tetrachloroethene (PCE) and chloroform in the sewer main in front of the duplex and at multiple sample locations within the sewer line upstream of the duplex. These test results combined with results from the prior multi-year study of the duplex indicate that the sewer line plays an important role in transport of VOCs from the subsurface source to the immediate vicinity of the duplex building envelope. [Display omitted] •The sewer line is an important pathway for VOC transport at the USEPA duplex.•The importance of this pathway was not identified during prior study of the duplex.•Sewer lines should be routinely evaluated during vapor intrusion investigations.