Building Trust. Engineering Success. Real-time Vapor Intrusion Investigations in Industrial Buildings Using Portable GC-MS Presented by: Paul Gallagher, P.G., C.P. Sanborn, Head & Associates, Inc.

2 Goal: to show how real-time field analytical capability can fast-track VI investigations and mitigation Presentation topics: Overview of portable GC-MS (HAPSITE®) Project examples  Baseline indoor air assessment  HVAC “experiments” to distinguish VI from interior VOC sources  Sleuthing for VOC entry pathways

3 Portable gas chromatograph-mass spectrometer (GC/MS) HAPSITE® (Hazardous Air Pollutants on-Site) manufactured by INFICON, Syracuse, NY A powerful tool in the right hands Pros Detects PCE and TCE to <1 µg/m 3 levels Portable – good for sleuthing VI entry pathways Approx. 10 mins per sample, and up to samples per day Cons Requires special training and experience Not found to be reliable for certain compounds (e.g., dichloroethene, dichloroethane, vinyl chloride)

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5 HVAC Shutdown Test Procedure 1.Baseline – screen/sample while HVAC systems are operating normally. 2.Shut down HVAC systems and screen/sample. 3.Impose negative pressure on structure (e.g. activate exhaust fans) and screen/sample. 4.Re-store HVAC systems to normal operations and screen/sample.

6 Project Example #1 - Controlled Pressure Method for an industrial building using HAPSITE portable GC/MS (real-time VI assessment of a 10,000 ft 2 manufacturing space)

7 Initial conditions Normal HVAC operations, room ~neutral pressure

8 Test conditions: Shutdown HVAC supply air, and activate exhaust fans, neg. pressure in room PCE/TCE increase

9 Post-Test conditions: Shutdown exhaust fans, and restore supply air, neutral pressure in room PCE/TCE return to initial levels

10 Response of indoor VOC levels to change in room pressure: negative pressure = higher VOC levels Results indicate VI rather than interior background condition. Sample location IDs

11 Identifying the VOC entry points: Expansion joints in floor slab 1900 / / / / / 1300

12 Project Example #2 - Using the portable GC-MS to Verify the Performance of Mitigation Measures Initial Conditions: VOC (ug/m3): 60 grab samples over 2 days

13 Return air intake – AHU room acts as the return air plenum and entire room is under neg. pressure Return air flow AHU room VOC ~ 220 ug/m 3 Identifying the VOC entry pathways: Air handler unit rooms under negative pressure Floor trench (VOC ~ 2700 ug/m 3 ) Sniffing for VI from cracks under rugs

14 Identifying the VOC entry pathways Foundation underdrain network – interior manholes VOC ~ 3,200 ug/m 3 in manhole; air flow out of manhole and into bldg Air flow

15 Multi-pronged mitigation approach 1.Sealing of floor slab penetrations Pipe and conduit penetrations through the floor slab Condensate sumps in mechanical rooms Expansion joints in the floor slab Cracks in the floor, particularly around building columns and footings 2.Depressurization of floor trenches and manholes 3.Sub-slab vapor extraction

16 Post-Mitigation VOC Screening – 1 day VOC (ug/m 3 )

17 Mitigation Performance Results

18 Hapsite set up on mobile cart in laundry roomSniffing for VI from cracks under rugs Analyzed ~80 samples over 2 days in 25 apartments Analyzed household products, art supplies, and potential VI pathways Results: PCE due to art supplies. TCE due to VI through floor cracks. Project Example #3 – Evaluating Sources for PCE and TCE in indoor air in a former mill building converted to apartments Courtesy of StoneHill Environmental

19 Project Example #4 Diagnosing VI using HVAC Shutdown Sec p.80 “…it may be useful…to diagnose vapor intrusion…under conditions when the HVAC system is not operating.”

20 Assertion: If indoor air levels are acceptable when the HVAC system is shut down, or when the building/space is under negative pressure, then VI controls or mitigation is unnecessary. And long-term periodic sampling is unnecessary

21 Project Example #3 - 60,000 sq. ft. manufacturing bldg What happens if HVAC is turned down or off in certain areas?

22 60,000 sq. ft. manufacturing bldg What happens if HVAC is turned down or off in certain areas?

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24 60,000 sq. ft. manufacturing bldg What happens if HVAC is turned down or off in certain areas?

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26 Summary: Rapid, effective VI investigations can be conducted using real-time analytical instruments, understanding of HVAC system operations and influence, and good detective work. Real-time analytical capability allows for:  “experimentation” (e.g. induce positive or negative pressure) to distinguish VI vs. interior VOC sources/ background conditions, and possibly avoid sub-slab sampling.  Trial testing of mitigation and effectiveness (e.g., increased pressure, air exchange, sealing penetrations) before committing long-term resources.  HVAC system shutdown testing to assess “worst case” conditions for VI Large potential cost savings compared to conventional, iterative investigations and sampling methods (e.g., Summa TO-15).

27 Further reading/references: Sanborn Head technical papers available at: Beckley, L., et al., Definitive Vapor Intrusion Investigations Using On-site GC/MS Analysis and Building Pressure Control, Vapor Intrusion 2012, Air & Waste Management Association, Denver, CO, October 3-4, McHugh, T.E., et. al., Evaluation of Vapor Intrusion Using Controlled Building Pressure, Environmental Science & Technology, 2012, 46(9), pp Millner, C., et. al., Addressing Background Sources of VOCs During Vapor Intrusion Investigations, The 28th Annual international Conference on Soils, Sediments, Water and Energy, AEHS Foundation, Amherst, MA, October 15, Any questions, please contact: Paul Gallagher or