1. Potential Addition of Vapor Intrusion to the Hazard Ranking System U.S. EPA Office of Solid Waste and Emergency Response February 24, 2011 Listening Session Arlington, VA 1

2. What is Vapor Intrusion and Why Could It Pose a Risk? 2

3. Why Consider Adding Vapor Intrusion to the HRS? Adding a mechanism for including the threat due to vapor intrusion to the HRS allows for the consideration of sites where vapor intrusion poses a significant threat. State and tribal input and a recommendation by the Government Accountability Office in May 2010 has led EPA to consider including a vapor intrusion mechanism in the HRS. EPA solicited public input on this topic in a notice published in the Federal Register on January 31, 2011. Public comment period ends April 16, 2011. 3

4. CERCLA and the HRS The CERCLA (Superfund) program was created to identify, and, if necessary, remediate releases of hazardous substances that pose a significant threat to human health and the environment. Placement of a site on the NPL makes the site eligible for federal funding for possible site remediation. Within the Superfund program, the HRS is the main mechanism for identifying releases at sites that may warrant further investigation and possible remediation. The role of the HRS is as an initial screening tool. It is not a site specific risk assessment. 4

5. How Does the HRS Work? HRS Structure 5

6. What Threats Does the Present HRS Evaluate? Groundwater Migration Pathway – Reflects the threat posed by contamination entering groundwater and migrating to drinking water wells Surface Water Migration Pathway – Reflects the threat posed by contaminants entering surface water and migrating to drinking water withdrawals, environments along the water, or human food chain fisheries Air Migration Pathway – Reflects the threat posed by contaminants entering ambient air and migrating via ambient air to humans and sensitive environments Soil Exposure Pathway – Reflects the threat posed by exposure to contamination resulting from individuals and sensitive environments coming in contact with outdoor surficial contamination 6

7. How Does It All Add Up? HRS Scoring Structure: HRS scoring structure generates one site score (0 to 100) Site score must be greater than or equal to 28.50 to qualify for inclusion on the National Priorities List 7

8. Information Request EPA requests input on the following topics: 1. The level and extent of vapor intrusion contamination that would warrant evaluation for placement on the NPL, as well as the identification of screening level information sufficient to perform this evaluation. 8

9. Information Request 2. Methods for incorporating vapor intrusion into the HRS while, to the extent possible, maintaining the structure of the other pathways in the current HRS and retaining that same structure throughout the new mechanism for vapor intrusion. 9

10. Information Request 3. Consideration of the importance of evaluating the potential threat to populations not demonstrated to be exposed to contaminant intrusion. 10

11. Information Request 4. The identification of sampling procedures available and practical to detect the presence of contamination due to vapor intrusion. 11

12. Information Request 5. The availability of screening sampling strategies that can adequately compensate for the variability in vapor intrusion rates under different climatic and seasonal conditions. 12

13. Information Request 6. Identification of analytical methods that are sufficiently precise and accurate to demonstrate a significant increase in contaminant levels from vapor intrusion. 13

14. Information Request 7. The importance of the threat posed by exposure to contaminant vapor intrusion via inhalation, dermal contact with the vapors or condensate on surfaces, and ingestion. 14

15. Information Request 8. The identification of what environmental factors (e.g., porosity of soil, presence of a contaminated aquifer, climate) and structural and lifestyle factors (e.g., houses with basements) should appropriately be considered in determining whether a site warrants sampling for contaminant vapor intrusion. 15

16. Information Request 9. In addition to residences, schools and other occupied structures, the identification of structures in which contaminant vapor intrusion could result in a significant threat to human health (e.g., community recreation centers, cultural centers, museums, athletic facilities). 16

17. Information Request 10. The possible need to consider not only contaminant vapor intrusion, but also intrusion of contaminants in solid (i.e., particulates) and liquid forms. 17

18. Information Request In addition to these topics, EPA also solicits input on: community outreach methods that would be most effective in gathering and disseminating information regarding this potential addition to the HRS the identification of possible vapor intrusion sites 18

19. Please submit all comments on the potential addition of vapor intrusion to the Hazard Ranking System to: www.regulations.govwww.regulations.gov – Submit comments to docket ID #: EPA–HQ– SFUND–2010–1086 Questions on this presentation? Next Steps 19

20. For Further Information Please visit EPA’s “Potential Addition of Vapor Intrusion” website (http://www.epa.gov/ superfund/sites/npl/hrsaddition.htm) for further information.http://www.epa.gov/ superfund/sites/npl/hrsaddition.htm 20