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EPA Regional Groundwater and   Vapor Intrusion Update          NAS Moffett Field Restoration Advisory Board Meeting       ...
TCE Plume andEstimated CaptureZone – A/A1 Aquifer(0 - 45 feet below ground surface)
TCE Plume andEstimated CaptureZone - B1/A2 Zone(50 - 75 feet bgs)
TCE PlumeEstimated CaptureZone – B2 Aquifer(75 - 110 feet bgs)
Hydraulic Containment Work        Completed• Advanced cone-penetrometers to evaluate  types of soil in specific areas• Col...
Areas ofInvestigation –A/A1 AquiferZone
Areas ofInvestigation –B1/A2 Aquifer Zone
Areas of InvestigationB2 Aquifer Zone
Preliminary Findings• Plume margins confirmed in each area with  the exception of residential area south of 101• High tric...
TCE GroundwaterResults Along WesternMargins – North ofHighway 101
Maximum TCE Groundwater Results Western Margins –       South of Highway 101 (A/A1 Aquifer)
Maximum TCE Groundwater Results Western Margins –       South of Highway 101 (B1/A2 Aquifer)
High Priority Areas for Indoor AirSampling
Groundwater – Next Steps  • Determine extent of hot spots with further step-outs    in residential area south of 101  • In...
Questions
Groundwater Update    Sitewide Groundwater Supplemental              Feasibility Study• Stakeholder Comments on Preliminar...
Stakeholder and Remedy Review          Board Comments• In situ redox technologies (comments related  to safety, support, i...
Stakeholder and Remedy Review          Board Comments• Evaluate improvements to slurry walls• Better explain approach to u...
EPA Next Steps• Meetings with stakeholders to discuss  concerns and path forward for the Site-wide  groundwater remedy
Questions
EPA Contact InformationPenny ReddyEPA Groundwater Project Manager415.972.3108Reddy.Penny@epa.govAlana LeeEPA Vapor Intrusi...
Additional Slides
Remedy Review Board Comments on      Groundwater Feasibility Study•   Provide a metric for measuring vapor intrusion risk ...
Community Advisory Board                Comments•   Support for Alternative 4 (in situ redox plus optimized system and    ...
Community Advisory Board         Comments (Continued)• Model should be relied upon only for comparative  analysis• Concern...
Projected VOC Plume – A Aquifer           (0 to 45 feet bgs)    1992        2009            2019
Projected VOC Plume – B1/A2 Aquifer             (50 to 75 feet bgs)      1992         2009            2019
Projected VOC Plume- B2 Aquifer          (75 to 110 feet bgs)
Moffett RAB: EPA Regional Groundwater and Vapor Intrusion Update
Moffett RAB: EPA Regional Groundwater and Vapor Intrusion Update
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Moffett RAB: EPA Regional Groundwater and Vapor Intrusion Update

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Presentation to the February 7, 2013, Moffett Restoration Advisory Board meeting by Alana Lee of EPA.

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Transcript of "Moffett RAB: EPA Regional Groundwater and Vapor Intrusion Update"

  1. 1. EPA Regional Groundwater and Vapor Intrusion Update NAS Moffett Field Restoration Advisory Board Meeting February 7, 2013
  2. 2. TCE Plume andEstimated CaptureZone – A/A1 Aquifer(0 - 45 feet below ground surface)
  3. 3. TCE Plume andEstimated CaptureZone - B1/A2 Zone(50 - 75 feet bgs)
  4. 4. TCE PlumeEstimated CaptureZone – B2 Aquifer(75 - 110 feet bgs)
  5. 5. Hydraulic Containment Work Completed• Advanced cone-penetrometers to evaluate types of soil in specific areas• Collected grab groundwater samples from boreholes to select well locations to define plume margins and characterize B2 Aquifer• Sampled wells at toe of plume in A/A1 Aquifer Zone to evaluate plume stability
  6. 6. Areas ofInvestigation –A/A1 AquiferZone
  7. 7. Areas ofInvestigation –B1/A2 Aquifer Zone
  8. 8. Areas of InvestigationB2 Aquifer Zone
  9. 9. Preliminary Findings• Plume margins confirmed in each area with the exception of residential area south of 101• High trichloroethene (TCE) in shallow groundwater beyond estimated plume boundary in residential area south of 101• Plume area characterized in B2 Aquifer• Soil is heterogeneous with discrete layers of contamination
  10. 10. TCE GroundwaterResults Along WesternMargins – North ofHighway 101
  11. 11. Maximum TCE Groundwater Results Western Margins – South of Highway 101 (A/A1 Aquifer)
  12. 12. Maximum TCE Groundwater Results Western Margins – South of Highway 101 (B1/A2 Aquifer)
  13. 13. High Priority Areas for Indoor AirSampling
  14. 14. Groundwater – Next Steps • Determine extent of hot spots with further step-outs in residential area south of 101 • Install extraction wells to clean up hotspot areas • Finalize report summarizing data • Install and sample monitoring wells near plume boundaries (western, eastern, toe of plume) • Continue monitoring existing wells at toe of plume • Review plume boundaries • Conduct modeling to evaluate capture in B2 Aquifer
  15. 15. Questions
  16. 16. Groundwater Update Sitewide Groundwater Supplemental Feasibility Study• Stakeholder Comments on Preliminary Draft (July 2012)• National Remedy Review Board Meeting (July 24, 2012)• National Remedy Review Board Comments (January 14, 2013)
  17. 17. Stakeholder and Remedy Review Board Comments• In situ redox technologies (comments related to safety, support, implementation, cost)• Integrate groundwater and vapor intrusion (VI) remedy; provide metric for VI risk reduction related to groundwater• Address role of vadose zone contamination
  18. 18. Stakeholder and Remedy Review Board Comments• Evaluate improvements to slurry walls• Better explain approach to using monitored natural attenuation (MNA)• Areas of cleanup should also focus on sensitive populations and future development
  19. 19. EPA Next Steps• Meetings with stakeholders to discuss concerns and path forward for the Site-wide groundwater remedy
  20. 20. Questions
  21. 21. EPA Contact InformationPenny ReddyEPA Groundwater Project Manager415.972.3108Reddy.Penny@epa.govAlana LeeEPA Vapor Intrusion Project Manager415.972.3141Lee.Alana@epa.gov For More Information www.epa.gov/region9/mew www.epa.gov/region9/moffettfield
  22. 22. Additional Slides
  23. 23. Remedy Review Board Comments on Groundwater Feasibility Study• Provide a metric for measuring vapor intrusion risk reduction related to accelerated groundwater cleanup• Assess potential presence of dense non-aqueous phase liquid• Compile results of all in-situ redox technologies and provide more details on how the technologies would be applied and when• Address the role of vadose zone contamination• Evaluate improvements to slurry walls• Better explain approach to using monitored natural attenuation as component of remedy
  24. 24. Community Advisory Board Comments• Support for Alternative 4 (in situ redox plus optimized system and monitored natural attenuation)• Groundwater feasibility study should be integrated with vapor intrusion remedy• Areas for cleanup should not just include those with high concentrations but all areas of sensitive populations and future development• Monitored natural attenuation should not be considered until more active treatment is completed and concentrations fall below 50 ppb• Deployment of Permeable Reactive Barriers reconsidered
  25. 25. Community Advisory Board Comments (Continued)• Model should be relied upon only for comparative analysis• Concerns with safety to building occupants using in situ technologies beneath buildings and end results if only partial treatment• FS needs more discussion on difficulties implementing in situ treatment technologies beneath buildings and associated disruptions to properties
  26. 26. Projected VOC Plume – A Aquifer (0 to 45 feet bgs) 1992 2009 2019
  27. 27. Projected VOC Plume – B1/A2 Aquifer (50 to 75 feet bgs) 1992 2009 2019
  28. 28. Projected VOC Plume- B2 Aquifer (75 to 110 feet bgs)
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