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Vapor Intrusion

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Vapor Intrusion

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    1. Vapor Intrusion Robert J. Zwald, CPG Fishbeck, Thompson, Carr & Huber, Inc. A&WMA – West Michigan Chapter 16th Annual Spring Conference March 19, 2008

    2. Introduction ASTM Standard for Vapor Intrusion Vapor Intrusion in Michigan Mitigation Case Study

    3. Definition Vapor intrusion (VI) is an indoor air quality condition that occurs when evaporating chemicals migrate from polluted soil and groundwater in the form of hazardous vapors into overlying buildings.

    4. ASTM Standard

    5. ASTM E 2600 ASTM E 2600, “Standard Practice for Assessment of Vapor Intrusion into Structures on Property Involved in Real Estate Transactions” – Adopted March 4, 2008 Addresses vapor intrusion (VI) arising from contaminated soil and groundwater specifically as it can impact real estate transactions It provides guidance on the VI assessment process, from screening to mitigation

    6. Terminology Chemicals of Concern (COC): Chemical that can potentially migrate as a vapor into a structure, and is generally recognized as having an adverse impact on human health. COC generally meet specific criteria for volatility and toxicity. Vapor Intrusion Condition (VIC): The presence or likely presence of any chemicals of concern in the indoor air environment of existing or planned structures on a property caused by the release of vapor from contaminated soil or groundwater on the property or within close proximity to the property, at a concentration that presents or may present unacceptable health risk to occupants. PVIC – Potential VIC

    7. Relationship to a Phase I ESA VI is a non-scope consideration in E 1527 May be included as supplement Phase I information used as part of VI screening Assumptions made in Phase I carry to VI screening under ASTM VI standard

    8. Four Tiered Assessment Tier 1 – Initial Screening Tier 2 – Semi-Site Specific Screening Tier 3 – VIC Assessment Tier 4 – Mitigation

    9. Four Tiered Assessment cont’d Tiers 1 and 2 identify if a PVIC exists Tier 3 identifies approaches to assess if a vapor intrusion condition exists that can threaten human health Tier 4 identifies general mitigation alternatives

    10. Tier 1 – Screening Does PVIC exist within area of concern? COCs within 1/3 mile Petroleum Hydrocarbons 1/10 mile Upgradient default to ASTM radii Use standard Phase I ESA practices to determine potential Professional judgment

    11. Tier 2 – Numerical Screening Review of existing data Regulatory records Previous investigations Collect new data Soil/groundwater sampling Soil gas sampling Combination, as needed …and, oh yeah…professional judgment

    12. Tier 3 – VIC Assessment Does VIC exist? Interior (in or below occupied structure) testing Modeling Combination Endpoints defined Yes No Maybe/maybe not…

    13. Tier 4 – Mitigation VIC exists VIC maybe exists Measures need to be taken

    14. The Obligatory Flowchart ….zzzzzz….

    15. Non-Scope Considerations Explosion hazards (methane) Naturally occurring gasses Indoor air quality contributors Other

    16. A Little More on Methane Not a “COC” Non-toxic Very transient by nature Natural and man-made sources

    17. Vapor Intrusion in Michigan

    18. Upcoming Rules and Regs Draft, peer review, revised, under development, etc… Op Memo No. 4, Attachment 4, Soil Gas and Indoor Air Sampling strategy guidance Mitigation options Technical Support Document for Indoor Air and Soil Gas

    19. Upcoming Rules and Regs cont’d Attachments to Op Memo No. 2 Attachment 9: Analytical methods, parameters and reporting limits for soil gas Attachment 10: Target Method Detection Limits for ambient air Op Memo 4, Attachment 5 – Methane Sampling strategy guidance Mitigation options

    20. Implications of E 2600 Michigan’s exposure based cleanup criteria already encourages pathway evaluation ESA/BEA cleanup liability scheme should be minimally affected Could be “due care” concerns

    21. Mitigation

    22. Mitigation Options Institutional Controls Deed restrictions Other land use mechanisms Engineering Controls Source Removal/Treatment Barriers/Liners/Venting

    23. Mitigation Options cont’d Intrinsically Safe Building Design HVAC system controls Open air basement/first floor Monitors/Alarms Combinations of above options

    24. Case Study Landfill Redevelopment Auburn Hills and Orion Township, Michigan

    25. Background Former unregulated landfill (dump) 145 Acres, in Oakland County’s “Automation Alley” 60 acres of waste, up to 80 feet deep Minor hits of VOCs, including TCE, PCE, benzene Methane levels up to 80% in air Commercial/Industrial Park

    29. Mitigation Solutions Source Removal Subfloor Venting Vapor Barriers Building Controls Indoor Air Monitoring HVAC

    30. Source Removal Extensive SVE system Over 60 extraction wells Over 10,000 feet of manifold piping Single discharge point Flare treatment

    32. Subfloor Venting / Vapor Barrier Series of perforated pipes below slab Captures gas and prevents buildup Vented to atmosphere Optional tie in to SVE system “Liquid Boot” spray-on membrane Between vents and slab Optimal perforation integrity

    35. Building Controls Combustible gas indicators (CGI) throughout building Tied into fire alarm systems Low level alarm triggers HVAC and alert High level alarm triggers fire alarm and evacuation Bullet

    38. Thank You www.ftch.com

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