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WAITING TO EXHALE – OR HOW TO MANUEVER THROUGH THE INDOOR AIR MAZE

WAITING TO EXHALE – OR HOW TO MANUEVER THROUGH THE INDOOR AIR MAZE. Vapor Intrusion Pathway. By: Lisa Campe, MPH, LSP Woodard & Curran, Inc. Can be a Public Health “Problem” Vapor Intrusion can be a key exposure pathway from both soil and/or groundwater sources

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WAITING TO EXHALE – OR HOW TO MANUEVER THROUGH THE INDOOR AIR MAZE

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  1. WAITING TO EXHALE – OR HOW TO MANUEVER THROUGH THE INDOOR AIR MAZE Vapor Intrusion Pathway By: Lisa Campe, MPH, LSP Woodard & Curran, Inc.

  2. Can be a Public Health “Problem” Vapor Intrusion can be a key exposure pathway from both soil and/or groundwater sources Indoor Air can become impacted by volatile subsurface chemicals Inhalation of indoor air contaminants can pose a health risk HOW DOES VAPOR INTRUSION FIT IN?

  3. Regulatory Framework requires it Risk Assessment Components in Georgia Voluntary Remediation Program Act (VRP) and Hazardous Site Response Act (HSRA) VRP Performance Standard to reduce exposure to “safe levels” HSRA Type 1 (residential) and 3 (comm./ind.) Standards - risk assessment “built in” Type 2 (res.) and Type 4 (c./i.) – can use site-specific risk assessment Type 5 – consider engineering controls/restrictive covenants/pathway elimination HOW DOES VAPOR INTRUSION FIT IN?

  4. Ambient Air Soil Vapor Groundwater Chemical Source

  5. Indoor Air Pathway Groundwater-to-indoor air pathway now a widely recognized exposure pathway Exposure assessment is in one sense simple – breathing of indoor air Difficulty introduced by uncertainty in pathway completeness & significance Significant number of sites have volatile organic contaminants (VOCs)

  6. Can’t find “alternate” source of air - health concerns Assessment and mitigation can be costly and complex Liability if impact tenants/owners of subject or nearby properties Property value diminution Federal and State regulatory focus on pathway Vapor Intrusion - Why We Need to Pay Attention

  7. Concentrations predicted in the point of entry room Vapors enter through the crack around the perimeter of the foundation Default mode based on a “tight” residential structure Steady-state conditions apply Source of vapors can be groundwater, soil, soil-gas, or NAPL Significant preferential flow pathways (e.g., sumps and drains) are not considered Basic models do not account for source depletion Johnson & Ettinger ModelsConceptual Model (from U.S. EPA guidance)

  8. VOC concentrations near/under building in: Groundwater Soil Soil vapor Ambient air VOC concentrations in indoor air Results from screening of preferential pathways (e.g., sumps, cracks) Vapor Pathway Lines of Evidence

  9. How do you deal with background …(multiple sources)? How do you evaluate significance of the impacts? How do you evaluate future vs. present use? Reconciling measurements in multiple media and/or modeling can be difficult If do site-specific modeling, verify key assumptions Indoor Air Pathway Challenges

  10. Indoor air sampling is the most direct approach, but not always preferable Background levels exist for many contaminants Groundwater data should focus on water table screening; “clean lens” can be present Soil data can be relevant and difficult to deal with Soil-gas data should be considered/collected Preferential pathways (e.g., sumps) can be significant Sampling should assist in source id/delineation Data Collection to Evaluate VI

  11. Background sources of VOCs Consumer products (cleaners, paints etc.) Off-gassing from building materials, clothing, furnishings Occupant activities (solvent use, hobbies, smoking) Indoor emissions (e.g., heating systems) Ambient/outdoor sources

  12. EPA OSWER 2011 Background Indoor Air Study Background Indoor Air Concentrations of Volatile Organic Compounds in North American Residences (1990–2005): A Compilation of Statistics for Assessing Vapor Intrusion . EPA 530-R-10-001 http://www.epa.gov/oswer/vaporintrusion/documents/oswer-vapor-intrusion-background-Report-062411.pdf • Objective: “to illustrate the range and variability in VOC concentrations in indoor air resulting from sources OTHER THAN vapor intrusion.” • Full statistical distribution of background indoor air concentrations in 15 studies post-1990

  13. EPA 2011 Methods Mostly SUMMA 24 hour samples GC/MS, TO-14 and TO-15 analyses 25th, 50th, 75th, 90th and 95th percentile ranges based on individual study results (not all percentiles reported in each study) Number of studies included in survey varied by compound (for TCE – 14 and for PCE – 13)

  14. Source: EPA 2011

  15. Range of percentiles: TCE/PCE RL = reporting limit (not detected)

  16. Variable/unclear performance standards for closure across states and EPA regions Sites closed out years ago have been reopened by EPA and numerous state agencies Stringent and shifting policies impede investment and development Key Changes/Concerns about NewPolicies and Enforcement Actions

  17. Former Dry Cleaner source – highest concentrations near floor drain/equipment area PCE in groundwater, soil vapor and indoor air in/beneath cleaner and adjacent spaces Although concentrations in all media > NJ screening levels, soil vapor highest Case Study #1 - NJ Vapor Intrusion (VI) Site 000000.00 17

  18. Goal – Reduce indoor air to < screening levels (IASL) and soil vapor to < 10* SVSL (no ongoing monitoring) & close out Focused on addressing sub-slab source versus (previous consultant) low level groundwater contamination for under half the cost (100k vs. 250k) Three Prongs: Soil Vapor Extraction “Pilot Study” Soil excavation of floor drain area Passive Sub Slab Depressurization System (SSDS) Remedial Strategy for VI

  19. Before and After..

  20. Successfully demonstrated NFA for vapor intrusion (VI) pathway to NJDEP Groundwater being addressed via Monitored Natural Attenuation (MNA) Client is in process of obtaining reimbursement for VI work from Brownfields Reimbursement Fund The Light at the End of the Tunnel

  21. Case Study #2: Human HealthRedevelopment at Vapor Intrusion Site • Chlorinated solvents in soil and groundwater • Two buildings planned, one in a more contaminated area than the other • Modeled from GW – Significant Risk • Collected soil vapor from proposed footprints and modeled using soil vapor – Significant Risk

  22. Case Study 2 Cont. Performed soil remediation of potential source areas as part of footprint excavation / construction Integrated liquid boot and SSD systems into construction of slabs SVE for a few months to get the mass down in the “bad” area, then turned off

  23. Case Study 2 Cont. Collected two rounds of indoor air in the winter Demonstrated that chlorinated COPCs were not getting in / posing risk Prepared pre-occupancy letters / certification prior to tenant occupation Class A-3 RAO with AUL filed - AUL includes maintenance of SSDS and Slab

  24. Post Remediation Site Data (key constituents)

  25. Installation of liquid boot and overlying membrane

  26. Risk Management • Focus on data collection for risk assessment • Proactively evaluate risk and response actions prior to development • Consider changing climate of vapor intrusion policies as you proceed

  27. ITRC - http://www.itrcweb.org/guidancedocument.asp?tid=49 MassDEP - http://www.mass.gov/dep/cleanup/laws/vifin.pdf USEPA - http://www.epa.gov/wastes/hazard/correctiveaction/eis/vapor.htm NYDOH - http://www.health.ny.gov/environmental/investigations/soil_gas/svi_guidance/ Useful Links and Resources

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