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