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USEPA Region 2 Vapor Intrusion Study

USEPA Region 2 Vapor Intrusion Study. Cayuga Groundwater Contamination Site March 4, 2009. Site Background. 2001 to Present – EPA Field Study Installed 23 Multi-level monitoring wells Seven Rounds of groundwater sampling (>500 groundwater samples)

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USEPA Region 2 Vapor Intrusion Study

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  1. USEPA Region 2Vapor Intrusion Study Cayuga Groundwater Contamination Site March 4, 2009

  2. Site Background • 2001 to Present – EPA Field Study • Installed 23 Multi-level monitoring wells • Seven Rounds of groundwater sampling (>500 groundwater samples) • Quarterly water level measurement and geophysics support from USGS • Surface water/sediment samples (Owasco Outlet, Crane Brook, Union Springs)

  3. Site Background (cont’d) • Cayuga County DOH –1999-2008 - Multiple rounds of residential well sampling (>600 samples) • Remedial report and risk evaluations in progress

  4. Monitoring Wells

  5. Site Overview

  6. Ongoing Field Study Efforts • Additional field work under NYSDEC/EPA: • Additional monitoring wells • Additional groundwater sampling • Geophysical survey • Hydraulic testing

  7. Vapor Intrusion Study • EPA field study indicates that chlorinated volatile organic compounds (CVOCs) are present in groundwater • CVOC-contaminated groundwater extends from West Genesee St. to Union Springs • CVOCs in groundwater can form vapors that migrate in the subsurface • Potential exists for vapors to enter buildings • Vapor sampling is being conducted to determine if vapors are present in buildings

  8. Vapor Sampling Locations • Selection of locations based on existing data: • Location of CVOCs in groundwater • Location of CVOCs in surface water • Residential well data • Human health risk evaluation • Geologic/Hydrogeologic factors • Depth to contaminated groundwater (<100 feet) • Degree of bedrock fracturing • Presence of clean groundwater above contaminated zones

  9. Vapor Sampling Locations (cont’d) • Three areas identified that meet initial criteria: • South of West Genesee Street • Pinckney Road/Overbrook Drive Area • Union Springs

  10. South of West Genesee Street • Insert Figure 1

  11. Pinckney/Overbrook Area (east) • Insert Figure 2

  12. Pinckney Road (West)

  13. Union Springs Area (south) • Insert Figure 3

  14. Union Springs Area (north)

  15. Residential Vapor Intrusion Sampling Procedures • Presented by: • Gary Newhart – EPA

  16. Ventilation Ventilation Interior space Ambient air Ambient air Vadose Zone Subslab soil gas intruding into interior space Groundwater Contamination Vapor Pathway into Buildings

  17. Key Questions for Vapor Intrusion Impacts • Does groundwater or soil contamination exist? • Yes, in this case, so we move to the next step • Does subsurface gas contamination exist above guidelines? • Answered through collection of subslab soil gas • 3. If subsurface gas does exist above guidelines, is it entering the interior space? • Answered through collection of indoor air samples • 4. If gas contamination exists in the residence, are the concentrations elevated and related to contamination • - Answered by comparing results to health-based guidelines and conducting lifestyle and ambient investigation

  18. Monitoring and Sampling Strategy • Initial Sampling • - Subslab Location + Ambient (outdoor) • 2. Subsequent SUMMA Canister Sampling • - Subslab Location • - Basement Location • - First Floor Location

  19. Indoor Air and Sub-Slab Soil Gas Activities

  20. Drilling

  21. Placement and Cementing of the Probe

  22. Connection of the 3-Way Valve

  23. Vapor Sampling Apparatus

  24. Vapor Mitigation System

  25. What is a VI Matrix and how is it developed? • Chemical-specific • Considers potential health effects from long-term exposures for residents including children and adults • Exposure Frequency of 24 hours/day and 350 days/year • Exposure Duration is 30 years • Has comparison values for subslab soil gas and indoor air

  26. Vapor Intrusion Matrix for a Carcinogenic Chemical Step 1. Does the subslab concentration exceed x ug/m3?No = Vapor intrusion investigation is over for this building Yes = Consider indoor air sampling Step 2. Evaluate subslab and indoor air concentrations.

  27. Vapor Intrusion Matrix for a Non-Carcinogenic Chemical Step 1. Does the subslab concentration exceed x ug/m3?No = Vapor intrusion investigation is over for this building Yes = Consider indoor air sampling Step 2. Evaluate subslab and indoor air concentrations.

  28. VI Decisions • VI Profile • Subslab • Indoor/Basement • Indoor/First Floor Living Space • Ambient Concentrations • Confounding Internal Sources • Confounding External Sources

  29. Key Points in VI Decisions • Decision to remediate is not based on one piece of information • Complexity and uncertainty is associated with the fate and transport mechanism of vapors • Multiple lines of evidence are used in the decision making • Rely on “VI Team” to ensure consistency in decisions within EPA Region 2

  30. Contact Information • USEPA Remedial Project Manager - Isabel Rodrigues – (212) 637-4248 • USEPA Community Involvement Coordinator– Mike Basile - (716) 551-4410 • New York State DOH – Krista Anders – (518) 402-7860 • New York State DEC – Kevin Kelley – (315) 426-7421 • Cayuga County DOH – Eileen O’Conner (315) 253-1405

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