Vapor Intrusion Assessment and Mitigation Guidelines for Ohio EPA

1. Sample Collection and Evaluation of Vapor Intrusion to Indoor Air for the Division of Environmental Response and Revitalization CP Coffee, April 18, 2018

2. Most recent additions and issues: • Providing guidance for all the remedial programs in Ohio EPA Division of Environmental Response and Revitalization, (DERR), RCRA, CERCLA and VAP • Providing additional engineering considerations for remedial and mitigations systems • Providing clearer guidance on site specific considerations regarding monitoring and the termination of monitoring

3. Step 1 Conduct a Site Assessment. Step 2 Determine if there is the potential for any volatile and toxic chemicals of concern in soil or ground water. TCE and receptors? The process is generally the same but the timeframe is accelerated, we expect you to react quickly. Step 3 Develop a Conceptual Site Model and Data Quality Objectives (DQOs) for evaluating the vapor intrusion pathway. The DQOs and CSM are not static; these components are continually refined and revised as data are collected at the site.

4. Step 4 If the CSM indicates that the vapor intrusion pathway is potentially complete; sample the appropriate media, indoor air, exterior soil gas, ground water and sub-slab soil gas. Data from only one environmental medium is not sufficient to fully assess the vapor intrusion exposure pathway. A multiple lines of evidence approach, including temporal, is needed to evaluate pathway completeness from all environmental media. This is to ensure that the complete and potentially complete vapor intrusion exposure pathway to human receptors has been adequately characterized, the risk has been adequately estimated, the future possibilities are understood and considered, and to minimize all the possible uncertainties.

5. Step 5 Evaluate the data using modeling, screening levels, and/or site-specific data. Contact Ohio EPA if there is a possibility of imminent hazard. A number of tools can be used at this stage to determine if the vapor intrusion pathway poses a potential unacceptable risk for building occupants. Update the CSM depending on the outcome of data evaluation. If data indicate the possibility of an imminent hazard, Ohio EPA should be contacted as soon as possible. Additionally, don’t hesitate to act independently and ensure that receptors are informed, that immediate measures that would be effective in mitigating the risk are taken and that you have or are developing a plan of action looking forward. This plan would carry contingencies with the result of future data or future circumstances.

6. Step 6 Evaluate the potential risk and hazard from the vapor intrusion pathway. For remedial sites, if data evaluation indicates that concentrations are below screening values (VISL), those COCs are eliminated from further vapor intrusion assessment. For VAP properties, the screening values are used to calculate incremental site-wide risk or exposure pathway understanding. Step 7 If data evaluation indicates risk or hazard goals are or may be exceeded, then additional data may be collected, or a remedy may be implemented (see Step 8). If there is a potential for unacceptable risk, further investigation may include the following:

7. • Collecting data to define physical and chemical parameters for site-specific soil using recommended test methods. • Collecting soil gas samples to define the vapor ‘plume’ at sites where buildings do not exist. • Collecting subslab soil gas samples or crawl space samples at an existing building. • Collecting indoor air samples in conjunction with subslab soil gas samples .

8. Step 8 Remediation, Mitigating Indoor Air Exposure and/or Conducting Long-Term Monitoring. If data evaluation indicates the potential for unacceptable risk, there are several remedies that may be considered to mitigate vapor intrusion to indoor air.

9. Potential remedies may include: • Removing VOC contamination through site remediation. Verify. • Installing passive or active vent systems (existing buildings). O&M. • Installing passive and/or active vent systems/membrane systems (future buildings). O&M. • Design of ventilation systems to mitigate indoor air concentrations (HVAC). O&M. • Institutional controls restricting structures or types of structures on contaminated property. • The implementation and monitoring of appropriate engineered remedies to prevent or mitigate vapor intrusion. Monitoring of engineered controls must continue until risk-based clean-up levels as measured in environmental media have been met. O&M.

10. Remedial options require verification. Heating and cooling seasonal data is required (minimally two) for verification that a system is effective. Indoor air and subslab paired samples are most desirable, not only for verification but for long term monitoring as well. Plan for that. Manometer readings need to be mapped out and a baseline understood for the Operation and Maintenance (O&M) plan, the documentation of verification and long-term monitoring must be clearly laid out and maintained. Remedies that are constructed with source chosen for a site, long-term monitoring of soil gas and indoor air may be necessary under an O&M plan. The frequency of the monitoring will depend upon site-specific conditions and the degree of VOC contamination.

11. In Summary • Imminent Hazard ~ TCE ~ Beat Feet • Empirical Data ~ No Bulk Soil • VISL • Modeling is not useful

12. Next Steps • Up on the WWW for public comments • Please review and provide comments and suggestions • Please consider other remedial programs outside of the VAP • Please don’t hesitate to call me with questions or clarifications

13. The National Academies of Sciences, Engineering, and Medicine has convened a committee of experts to conduct a study that will review the scientific and technical basis of the Department of Defense’s proposed approach to developing an occupational exposure level (OEL) and cancer slope factor for trichloroethylene for settings in which vapor intrusion is the pathway of exposure.

14. Questions? Mike Allen Michael.allen@epa.ohio.gov 614-644-2322