Vapor Intrusion/Indoor Air Guidance Survey July 2010
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PAR S O N S FINAL Vapor Intrusion/Indoor Air Guidance Survey July 2010 Prepared for: MassDEP Massachusetts Department of Environmental Protection Prepared by: PAR S O N S FINAL - JULY 2010 Vapor Intrusion/Indoor Air Guidance Survey Final Report Vapor Intrusion Indoor Air Guidance Survey Prepared for: MassDEP Massachusetts Department of Environmental Protection Prepared by: PARSONS 100 High Street Boston, MA 02110 July 2010 FINAL - JULY 2010 Vapor Intrusion/Indoor Air Guidance Survey Table of Contents 1. INTRODUCTION ...................................................................................................... 3 2. STATE VAPOR INTRUSION MANAGEMENT PRACTICES ............................. 3 2.1 Survey Approach, Methodology, and Scope ........................................................ 3 2.1.1 States Surveyed ............................................................................................. 5 2.1.2 States’ Approval Scheme and VI Investigation Approval Process................5 2.2 Vapor Intrusion Modeling .................................................................................... 7 2.3 Engineering Controls .......................................................................................... 11 2.4 Institutional Controls .......................................................................................... 16 3. VAPOR BARRIERS TO MITIGATE VAPOR INTRUSION ................................. 17 3.1 Inclusion of Vapor Barriers in Building Codes .................................................. 17 3.2 Vapor Barrier Products ....................................................................................... 18 3.3 Effectiveness of Vapor Barriers ......................................................................... 19 3.4 Vapor Barrier Warranty Information..................................................................20 4. SUMMARY OF FINDINGS .................................................................................... 23 EXHIBITS Exhibit 1 Role of Modeling.........................................................................................8 Exhibit 2 Commonly Recommended ECs in state VI Guidance...............................11 Exhibit 3 State EC Monitoring Requirments.............................................................15 Exhibit 4 Frequency of IC Review by State..............................................................17 Exhibit 5 Summary of Vapor Barrier Warranties......................................................21 TABLES Table 1 Vapor Intrusion Guidance Survey Summary Table 2 States' Approval Scheme and VI Investigation Approval Process Table 3 Summary of Role of Modeling Table 4 Summary of Engineering Controls for VI Table 5 Summary of Institutional Controls and Site Closure Requirements for Vapor Intrusion Sites APPENDICES Appendix A Vapor Intrusion Guidance Survey Information - States Appendix B Vapor Intrusion Guidance Survey Information - Agencies Appendix C Phone Interview Templates Phone Interviews from April 14 to April 23, 2010 Appendix D Soil Vapor Barrier Product Information Appendix E City of Los Angeles Methane Barrier Test Criteria MassDEP PARSONS 1 Massachusetts Department of Environmental Protection FINAL - JULY 2010 Vapor Intrusion/Indoor Air Guidance Survey GLOSSARY ASTM American Society for Testing and Materials BTEX Benzene, toluene, ethylbenzene, and xylenes BWSC Bureau of Waste Site Cleanup DTSC Department of Toxic Substances Control EC Engineering Control ELCR Excess Lifetime Cancer Risk HDPE High Density Polyethylene IA Indoor Air IAC Indoor Air Criteria IBC International Building Code IC Institutional Control ITRC Interstate Technology and Regulatory Council J&E Johnson and Ettinger LEP Licensed Environmental Professional LLDPE Linear low-density polyethylene LSP Licensed Site Professional MassDEP Massachusetts Department of Environmental Protection Parsons Parsons Commercial Technology Group PM Project Manager PVC Polyvinyl Chloride OHM Oil and/or Hazardous Materials O&M Operations and Maintenance RBCA Risk Based Corrective Action SGC Soil Gas Criteria SMD Sub-Membrane Depressurization system SSD Sub-Slab Depressurization system SVE Soil Vapor Extraction SVOC Semi-volatile organic compounds UECA Uniform Environmental Covenants Act USEPA United States Environmental Protection Agency UST Underground Storage Tank VI Vapor Intrusion VOC Volatile organic compound MassDEP PARSONS 2 Massachusetts Department of Environmental Protection FINAL - JULY 2010 Vapor Intrusion/Indoor Air Guidance Survey 1. INTRODUCTION The Massachusetts Department of Environmental Protection (MassDEP) Bureau of Waste Site Cleanup’s (BWSC’s) Indoor Air Workgroup is in the process of developing guidance for addressing vapor intrusion (VI) at properties with soil or groundwater contamination. In order to inform their analysis and decision-making, MassDEP engaged Parsons Commercial Technology Group (Parsons) to conduct a national survey of available guidance and best practices for addressing vapor intrusion concerns in other states. The survey also included the guidance provided by United States Environmental Protection Agency (USEPA), Interstate Technology and Regulatory Council (ITRC), and American Society for Testing and Materials (ASTM). MassDEP also expressed specific interest in learning about the use of physical vapor barriers to mitigate vapor intrusion. As such, research on commercially available contaminated soil vapor barrier products and their use was included as a task in this project as well. This report presents the results of the state and agency survey and the vapor barrier research. The report is organized as follows: Section 2 discusses the survey of state and agency vapor intrusion practices; Section 3 discusses the vapor barrier research and findings; and Section 4 presents a summary of key findings. 2. STATE AND AGENCY VAPOR INTRUSION PRACTICES 2.1 Survey Approach, Methodology, and Scope The objective of the national survey was to obtain information on requirements and best practices from other states, USEPA, ITRC, and ASTM for the investigation and management of potential vapor intrusion issues. This information was gathered over a short timeframe between February 15 and April 26, 2010 from vapor intrusion guidance documents available on state websites and through phone calls to state agency contacts. In most cases, state environmental regulations were not reviewed. Based on discussions during the scoping meeting with MassDEP held on February 10, 2010 and a memo from MassDEP regarding Parsons’ preliminary findings, dated April 6, 2010, the research topics of interest included: Use of vapor intrusion modeling; States’ approval schemes; Types of engineering controls recommended and accepted; Site closeout requirements; Use of Institutional Controls (ICs) at sites where VI is a concern; MassDEP PARSONS 3 Massachusetts Department of Environmental Protection FINAL - JULY 2010 Vapor Intrusion/Indoor Air Guidance Survey If and how effectiveness of engineering controls is determined; and Monitoring of engineering and institutional controls. Parsons began by reviewing the available on-line vapor intrusion guidance documents at State environmental agency websites. All 50 states (including Massachusetts) were reviewed, although Parsons found that some states have not developed any guidance on their own. In addition, environmental agencies in some states rely on guidance developed by USEPA, ITRC, or ASTM. Detailed information gathered during the survey was recorded on a matrix, which is included electronically on CD as Appendices A and B for states and agencies, respectively. In conjunction with the on-line document survey, Parsons completed two separate phases of interviews; Phase I of interviews was completed between February 26 and March 15, 2010, and Phase II was completed between April 14 and April 23, 2010. The Phase II interviews were completed to gather additional information identified by MassDEP after reviewing the draft of this report Parsons contacted 28 state agencies and spoke with staff responsible for vapor intrusion and/or case management (these individuals are identified on the spreadsheet in Appendix A). The purpose of these interviews was to fill in gaps in written guidance, to learn about states’ review and approval practices, to learn about relevant guidance and regulations not directly referenced in vapor intrusion guidance, and to obtain additional information on how states actually addresses vapor intrusion issues as a practical matter. These interviews reveal differences in style and approach among the states. Information from the first phase of interviews conducted between February 26 and March 15, 2010 is provided in Appendix A on the summary matrix and is highlighted in blue. Notes from the Phase II interviews conducted between April 14 and April 23, 2010 are included in Appendix C. Copies of the questionnaires used as guides for both sets of phone interviews are also provided in Appendix C. It is noted that eight states (i.e., Arizona, Kansas, Minnesota, Mississippi, Montana, Pennsylvania, Virginia, and Wisconsin) were contacted and were not able to respond to our request for an interview within the time frame of this survey. Various other professional organizations have prepared guidance on vapor intrusion. These include USEPA, trade associations (i.e., State Coalition for Remediation of Drycleaners), a standards development organization (i.e., ASTM), the Department of Defense, and an intergovernmental/commercial