1. HEER Webinar (note change on mainland due to Daylight Savings Time) When:March 11 th, 2015 Time:11am-12pm Hawaii Time (2:00pm Pacific Time, 5:00pm Pacific Time) Who:Martin Schmidt (Cox-Colvin, Inc.) and Harry O’Neil (Beacon Environmental, Inc.) What:Use of Active and Passive Soil Gas Samples to Support Vapor Intrusion Investigations TCEPCE

2. Dungeons, Dragons, Pica Houses and the Need for Alternative, Vapor Intrusion Screening Tools Roger Brewer, Josh Nagashima, Mark Rigby, Martin Schmidt, Harry O’Neill February 18, 2015 contact: roger.brewer@doh.hawaii.gov

3. Reference Roger Brewer & Josh Nagashima: Hawai’i Dept of Health State vapor intrusion guidance Mark Rigby: Parsons Corporation, UC Santa Barbara Toxicology, risk assessment, vapor intrusion Martin Schmidt: Cox-Colvin and Associates, Inc. Vapor intrusion field investigations, Vapor Pins Harry O’Neill: Beacon Environmental Services, Inc. Vapor intrusion field investigations, passive soil gas Brewer, R., Nagashima, J., Rigby, M., Schmidt, M. and O'Neill, H. (2014), Estimation of Generic Subslab Attenuation Factors for Vapor Intrusion Investigations. Groundwater Monitoring & Remediation, 34: 79–92. http://onlinelibrary.wiley.com/doi/10.1111/gwmr.12086/full

4. Vapor Attenuation slab contaminated soil or groundwater source subslab vapors Method #1: Ratio of Vapor Entry to Indoor Air Exchange Indoor Air Exchange Rate (L/minute) Vapor Entry Rate (L/minute) Subslab AF = Vapor Entry Rate IAER

5. Example Vapor Intrusion Risk Regions VIR Region A(cold, +Alaska) Highest Risk VIR Region B 2 (warm) Moderate Risk VIR Region C (Med) Lower Risk VIR Region B 1 (Coastal) Moderate Risk VIR Region D (tropical) Lowest Risk Region A: High Vapor Flux, Low Indoor Air Exchange (SSAF = 0.003) Region B: Mod Vapor Flux, Mod Indoor Air Exchange (SSAF = 0.002) Region C: Lower Vapor Flux, High Indoor Air Exchange (SSAF = 0.0008) Region D: Low Vapor Flux, High Indoor Air Exchange (SSAF = 0.0005) VIR Region D (tropical) +Hawai’i

6. Method #2: Indoor Air and Subslab Soil Vapor Database Subslab AF = Conc. Indoor Air Conc. Soil Vapor Indoor Air Sample (µg/m 3 ) X Subslab Vapor Samples (µg/m 3 ) contaminated soil or groundwater source AF Scenario A: Homogeneous subslab vapor plume; Location of vapor entry point(s) unknown; Size and location of subslab vapor sample unimportant; Calculated subslab AFs identical.

7. Method #2: Indoor Air and Subslab Soil Vapor Database Subslab AF = Conc. Indoor Air Conc. Soil Vapor Indoor Air Sample (µg/m 3 ) X Subslab Vapor Samples (µg/m 3 ) contaminated soil or groundwater source Scenario B: Heterogeneous subslab vapor plume; Location of vapor entry point(s) unknown; Size and location of subslab vapor sample important; Calculated subslab AFs can vary widely; Correct AF unknown ? ?????

8. Effect of Heterogeneous Vapor Plumes in USEPA Vapor Intrusion Database? Many subslab samples representative of vapor entry point (median = 0.003)? Less Conservative More Conservative Subslab Attenuation Factor 0.10.01 0.001 1.0 0.0001 Frequency 95% UCL Nonrepresentative subslab samples collected from higher concentration area (false high attenuation)? Nonrepresentative subslab samples collected from lower concentration area (false low attenuation)?

9. Presentation and Recording of February 18 th Webinar Posted to HEER Web Page (“What’s New”) http://eha-web.doh.hawaii.gov/eha-cma/Org/HEER/

10. Example subslab areas covered by different volumes of subslab soil gas samples (assuming sample collected from first 15cm of fill under slab and 20% air-filled porosity); Total volume of air-filled pore space in first 15cm of subslab fill approximately 2,250 liters per 100m 2 area; Collection of large-volume samples more challenging in tight soils (increase # of samples). More and/or Bigger Samples are Better Subslab Vapor Sample Volume vs Approximate Area of Influence 100L 50L 50ml 1L 6L 200cm For example only

11. Today’s Webinar When:March 11 th, 2015 (11am-12pm HI Time) Who:Martin Schmidt (Cox-Colvin, Inc.) and Harry O’Neil (Beacon Environmental, Inc.) What:Use of Active and Passive Soil Gas Samples to Support Vapor Intrusion Investigations TCEPCE

12. Upcoming Webinars (contact roger.brewer@doh.hawaii.gov) When:To Be Announced Who:Various What: Environmental Hazard Management Plans (e.g., institutional and engineering controls); Unexploded ordinance; Discrete vs Multi-Increment Sampling Methods; MIS for sediment; Environmental Action Levels; etc.