Presentation to the Moffett Restoration Advisory Board, May 9, 2013, by Josh Van Bogaert, U.S. Army Corps of Engineers

1. US Army Corps of Engineers
BUILDING STRONG®
Air Sampling at the
Former Orion Park Housing Area
Josh Van Bogaert, P.E.
Louisville District
May 9, 2013

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Orion Park Housing Area (OPHA)
Presentation Overview
 Reason for Study
 Planning and Execution
►General planning info
►Sample types and locations
►Regional data
 Draft Final Report and Results
 Summary
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Former OPHA Location
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Study Area

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Reason for Study
 Trichloroethylene (TCE) in
shallow (0-40’ bgs)
groundwater beneath the
former OPHA
 EPA requested Army
investigation of indoor air
quality
 3 Buildings
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Study Area

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What is vapor
intrusion?
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Study Focus Areas
Three Buildings:
► Building 546 (MEPS)
► Building 593
(Navy Lodge)
► Building 685
(Office Building)
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Planning & Execution
 Work Plans based on EPA work plans and developed in
close collaboration with EPA using best industry
practices
 Sampling and analysis performed by USACE in
accordance with EPA-approved work plans
► 6 compounds selected for analysis
► All sample and alternate locations planned with EPA, 63d Army
Reserve, and building managers
► Results compared to EPA Region 9 risk-based screening levels
(SLs)
 Sampling conducted February 26-27 (Tues-Wed), 2013
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Sample Types
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 Compare OPHA Data
 Isolate OPHA concerns from regional influence
Regional Bay Area
Air Quality Monitoring
District Stations
Study Area

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Building 546 (MEPS)
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Building 593 (Navy Lodge)
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Building 685 (office building)
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Results
Indoor & Outdoor Air Exceedances
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Note: All results in µg/m3
 Benzene exceeded residential SL
► 3 of 3 outdoor air samples
► 9 of 10 indoor air samples

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Results
Sub-Slab Soil Gas Levels
Note: All results in µg/m3
 Benzene exceeded residential SL in:
► 2 of 9 sub-slab soil gas samples - Buildings 593 (Navy Lodge) and 685
(office building)
 Benzene exceeded non-residential SL in:
► 1 of 9 sub-slab soil gas samples - Building 593 (Navy Lodge)
 TCE exceeded residential SL in:
► 2 of 9 sub-slab soil gas samples - Building 546 (MEPS)

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Relative to Regional Ambient Air Levels
Note:
1. BAAQMD data (Redwood City and San Jose) are for
2012 outdoor air.
2. ND = non-detect
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Summary
 No exceedances of applicable EPA SLs
 Indoor and outdoor air
► No TCE exceedances of SLs in indoor air
► Benzene indoor air results less than non-residential SL
► Benzene results are less than the average regional outdoor air
level
► Benzene exceedances are likely due to ambient outdoor
presence
 Sub-slab soil gas
► Benzene and TCE present above SLs
► No impact to indoor air observed
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Next Steps
 Receive and respond to EPA comments on Draft Final
Report
 Finalize the Report
 Ensure conditions remain protective of human health
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Questions?
 Contact EPA for Draft Final Report
 Final Report will be online at:
www.epa.gov/region9/mew
 Hard copy will be available at the Information Repository:
Mountain View Public Library
585 Franklin Street
Mountain View, CA 94041
(650) 903-6337
 Questions for the Army:
Kristina Curley
US Army Environmental Command - Public Affairs
Kristina.curley@us.army.mil
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Wind Roses
Day Night