VAPOR INTRUSION GUIDANCE: SITE ASSESSMENT …

1 Charles D. Baker Matthew A. Beaton Governor Secretary Karyn E. Polito Martin Suuberg Lieutenant Governor Commissioner VAPOR INTRUSION guidance : site ASSESSMENT , MITIGATION AND CLOSURE. Policy #WSC-16-435. This document provides guidance on investigating, assessing, understanding, and mitigating VAPOR INTRUSION at disposal sites regulated under Massachusetts General Law chapter 21E and the Massachusetts Contingency Plan (the MCP or 310 CMR ). This document is intended solely as guidance . It does not create any substantive or procedural rights, and is not enforceable by any party in any administrative proceeding with the Commonwealth. This document provides guidance on approaches MassDEP considers acceptable for meeting the general requirements set forth in the MCP.

2 Parties using this guidance should be aware that other acceptable alternatives may be available for achieving compliance with general regulatory requirements. _____. Paul W. Locke Assistant Commissioner Bureau of Waste site Cleanup October 14, 2016. MassDEP VAPOR INTRUSION guidance : site ASSESSMENT , MITIGATION AND CLOSURE OCTOBER 2016. Contents DISCLAIMER .. V. 1. INTRODUCTION .. 1. PURPOSE .. 1. guidance OVERVIEW .. 2. WHEN TO EVALUATE THE VAPOR INTRUSION PATHWAY .. 3. VOCs in Indoor Air .. 5. VOCs in Soil .. 5. VOCs in Groundwater .. 6. Other Factors .. 7. 2. ASSESSMENT .. 10. CONCEPTUAL site Identification of Sources of VAPOR INTRUSION PATHWAY ASSESSMENT ..13. Groundwater ..14. Soil, Exterior Soil Gas and Sub-Slab Soil Gas.

3 17. Special Considerations for the ASSESSMENT of Petroleum VAPOR INTRUSION from Discrete, Well-defined and Stable Petroleum Sources of OHM ..21. Indoor Air ..24. Outdoor Air ..29. Non-Aqueous Phase Liquids ..31. Preferential Pathways ..31. Lines of Evidence Interpretation for the Presence of a Current VAPOR INTRUSION Pathway ..32. INDOOR AIR EXPOSURE ASSESSMENT ..35. Contaminants of Concern ..35. site Receptors, Activities, and Exposure Point Concentrations ..37. Exposure Assumptions ..41. RISK CHARACTERIZATION ..42. General Risk Characterization Requirements ..42. Method 1 Risk Characterizations ..43. Method 2 Risk Characterizations ..43. Method 3 Risk Characterizations ..43. 3. MITIGATION OF THE VAPOR INTRUSION PATHWAY.

4 45. ADDRESSING SOURCES OF OIL AND/OR HAZARDOUS MATERIAL CONTAMINATION AND. MIGRATION CONTROL ..45. RESPONSE ACTIONS TO QUICKLY REDUCE VOC CONCENTRATIONS IN INDOOR AIR ..47. Sealing of Cracks, Sumps, Floor Drains and Utility Conduit Penetrations ..47. Ventilation Using Windows, Doors, Vents and Building Pressurization and HVAC Modification ..49. Air Purification Units ..49. INDOOR AIR PATHWAY MITIGATION ..50. Conducting a Building Survey ..52. Permeability of Sub-Slab Materials ..53. Depth to Groundwater and Surface Water Concerns ..54. Other Considerations for Mitigation Systems ..55. i MassDEP VAPOR INTRUSION guidance : site ASSESSMENT , MITIGATION AND CLOSURE OCTOBER 2016. ACTIVE MITIGATION SYSTEMS.

5 55. Active Sub-Slab Depressurization (SSD) Systems ..55. Active Drain Tile Depressurization (DTD) ..56. Active Block-Wall Depressurization (BWD) ..57. Active Sub-Membrane Depressurization (SMD) Systems ..58. Off-Gas Treatment ..59. Active Pressurization Techniques ..59. PASSIVE MEASURES ..59. VAPOR Passive Venting ..61. Aerated Floor DEMONSTRATION OF MITIGATION EFFECTIVENESS, MAINTENANCE AND MONITORING ..63. Performance Standards ..63. Demonstration of Effectiveness for Active Mitigation Systems ..63. Demonstration of Effectiveness of Passive Mitigation Measures ..68. Monitoring Telemetry on Active Mitigation Systems ..70. CLOSURE SAMPLING TO DEMONSTRATE THAT A MITIGATION SYSTEM IS NO LONGER.

6 REQUIRED ..71. 4. REGULATORY FRAMEWORK .. 72. COMMON REPORTING OBLIGATIONS RELATED TO THE VAPOR INTRUSION PATHWAY ..72. 2-Hour Notifications for Imminent Hazards ..72. 72-Hour Notifications Potentially Relevant to the VAPOR INTRUSION Pathway ..73. 120-Day Notifications Potentially Relevant to the VAPOR INTRUSION Notification and Releases to the Interior of Buildings ..76. Downgradient Property Status ..77. IMMEDIATE RESPONSE ACTIONS (IRAS)..78. Immediate Response Action Submittals ..78. CRITICAL EXPOSURE PATHWAYS ..80. CEP Feasibility Evaluations ..81. Generally Feasible Response Actions to Address Generally Infeasible Response Actions to Address CEP ..84. Rebutting the MCP Presumption for CEP Elimination/Mitigation.

7 84. Documentation of a CEP Feasibility Evaluation ..85. CEP Closure - Immediate Response Action Completion (IRAC) Criteria and Possible Outcomes ..86. TIER CLASSIFICATION AND THE INDOOR AIR Reclassification after an Initial Tier Classification ..89. Conducting Phase III Feasibility Evaluations ..90. Transitioning Preliminary Response Actions to Comprehensive Response Actions ..91. Phase IV and Phase V Comprehensive Response Actions ..91. REQUIREMENTS AND CONSIDERATIONS FOR CLOSURE AT SITES WITH VAPOR INTRUSION . PATHWAYS OR Closure at a Portion of a Disposal site ..94. Closure Prior to Tier Classification at Sites with VAPOR INTRUSION Mitigation ..95. PERMANENT SOLUTIONS AND TEMPORARY SOLUTIONS.

8 95. Permanent Solutions with No Conditions ..97. Permanent Solutions with Conditions ..98. Implementing and Operating an AEPMM as part of a Permanent Solution with Conditions ..109. ii MassDEP VAPOR INTRUSION guidance : site ASSESSMENT , MITIGATION AND CLOSURE OCTOBER 2016. Temporary Solutions ..114. POST-CLOSURE REQUIREMENTS AND CONSIDERATIONS FOR DISPOSAL SITES WITH VAPOR . INTRUSION CONCERNS ..115. Voluntary Continuation of VAPOR INTRUSION Mitigation ..115. Post-Closure Work at a Disposal site with a Permanent Solution with Conditions and an AUL ..116. Post-Closure Work at a Disposal site with a Permanent Solution with Conditions and No AUL ..117. New Buildings Constructed at a Disposal site Where the Potential for the VAPOR INTRUSION Pathway Exists.

9 117. 5. COMMUNICATION AND PUBLIC INVOLVEMENT .. 119. INTRODUCTION ..119. REQUIREMENTS FOR NOTIFICATION OF PROPERTY OWNERS AND AFFECTED INDIVIDUALS120. Notice of Environmental Sampling (Form BWSC123) ..120. Notice Related to Immediate Response Actions (Form BWSC124) ..120. Notification of Owners of Property within the Boundaries of a Disposal site (Form BWSC122) ..121. GENERAL PUBLIC NOTIFICATION AND INVOLVEMENT ..122. Public Involvement Opportunities During Preliminary Response Actions ..122. Public Involvement Plan (PIP) Designation for Disposal Sites ..122. NOTICE TO LOCAL OFFICIALS ..123. COORDINATION WITH LOCAL OFFICIALS ..123. OPTIONAL PUBLIC INVOLVEMENT ACTIVITIES ..124. 6. OBTAINING ACCESS AT VAPOR INTRUSION SITES.

10 126. APPENDIX I - Indoor Air Threshold Values for the Evaluation of a VAPOR INTRUSION Pathway APPENDIX II - Sub-Slab Soil Gas Screening Values APPENDIX III - Air Sampling Information APPENDIX IV - MassDEP's Recommended Specifications for the Design and Construction of SSD Systems REFERENCES. iii MassDEP VAPOR INTRUSION guidance : site ASSESSMENT , MITIGATION AND CLOSURE OCTOBER 2016. LIST OF ACRONYMS. Active Exposure Pathway NAPL Nonaqueous Phase Liquid AEPMM. Mitigation Measure NSH No Substantial Hazard Air-Phase Petroleum NSR No Significant Risk APH. Hydrocarbon OHM Oil or Hazardous Material APU Air Purifying Unit PCE Tetrachloroethylene AUL Activity and Use Limitation PHC Petroleum Hydrocarbon Benzene, Toluene, Ethyl PID Photo-ionization Detector BTEX.