Text Box: Text Box: Page # Text Box: Volume 10, issue 2 Text Box: a preferential pathway for contaminant vapors that had entered the sewer lines from openings elsewhere along the lines. It is important to note that reports of sewer odors are typically found with vapor traps that have dried out or are no longer operating properly.” On Page 19... “The use of institutional controls (e.g., deed restrictions, environmental covenants) may be appropriate to ensure that future use of an affected property is protective of human health through the vapor intrusion pathway. Institutional controls could include land use restrictions, future building design requirements to address the potential for vapor intrusion, notification requirements for land owners/developers, or stipulations for further investigation of the vapor intrusion pathway during evaluation of specific future use scenarios. When institutional controls are not appropriate (or not permitted by the regulatory agency), investigators must delve deeper into their “toolbox” to assess vapor intrusion at undeveloped lands. In the end, it may be preferable to incorporate a vapor barrier and/or subslab venting system into the building design as a proactive approach.” On Page 20... “To be successful, agencies conducting or overseeing vapor intrusion (VI) investigations need to develop a strong community outreach program to educate and reassure the local community Text Box: about vapor intrusion in a meaningful, sensitive, and effective manner. Unlike any other contaminant pathway, vapor intrusion merits effective education of the affected community regarding the risk of soil gas migrating from the subsurface as well as background sources typically found in the building. Community Advisory Groups (CAGs) may assist in this process. CAGs are generally small groups of residents who meet regularly with agencies and responsible parties. They provide an opportunity for the public to gradually gain an understanding of the complexities of vapor studies. In such settings, initial adversarial relationships usually break down, and community members often come up with constructive advice.” ‘“Remediation” commonly refers to an action that reduces the level of contamination in the environmental medium (e.g., groundwater) that is acting as the source of the indoor air vapors. “Mitigation,” on the other hand, is generally applied to actions that prevent or minimize exposure. While the two terms are used interchangeably in this industry, the differences should be understood by the investigator. When an action is needed, a remedy or combination of remedies should be selected, implemented, operated, maintained, and monitored to properly respond to the vapor intrusion problem and bring the site to closure.’ On Page 21... “The initial step in assessing the vapor intrusion pathway is developing a conceptual site model based on all available data.” Text Box: “…evaluating the potential for vapor intrusion at a site of concern should be approached as a sequential process extending from the evaluation of initially available data through the determination of no further action or mitigation. This section is intended to help the investigator evaluate existing data and make decisions regarding the need to proceed to the investigative phase to collect additional data. Given that regulator-defined screening levels are often close to background levels for many compounds and that spatial/temporal variability and sampling bias are often present, the ultimate risk management decisions should be based upon multiple lines of evidence rather than upon a single line of evidence...” “An appropriate initial screening process will ensure that those sites most likely to pose unacceptable risk from vapor intrusion are retained for more detailed evaluation. It is also expected that some sites will be removed from further evaluation if it is demonstrated that the exposure pathway is and will remain incomplete, the COCs are not deemed sufficiently volatile (as defined by the regulatory agency) to pose a hazard, or the concentrations of the volatile chemicals fall below generic screening levels.” On Page 22... “The goal for developing a CSM in the assessment of the

ITRC Vapor intrusion intro - continued

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