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Vapor Intrusion Risk Pathway Regulatory Updates & Practical Strategies

Vapor Intrusion Risk Pathway Regulatory Updates & Practical Strategies. Kennedy-Jenks Webinar June 2010. Blayne Hartman Independent Consultant 760-925-7206 www.handpmg.com. What Is Vapor Intrusion?. Key Criteria Controlling Assessment: Risk level (1 in 10,000? 100,000? 1,000,000?)

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Vapor Intrusion Risk Pathway Regulatory Updates & Practical Strategies

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  1. Vapor Intrusion Risk Pathway Regulatory Updates & Practical Strategies Kennedy-Jenks WebinarJune 2010 Blayne Hartman Independent Consultant760-925-7206 www.handpmg.com

  2. What Is Vapor Intrusion? Key Criteria Controlling Assessment: • Risk level (1 in 10,000? 100,000? 1,000,000?) • Toxicity of Compounds • Exposure Factors (time, rates, ventilation)

  3. Why Do You Care About VI?(Risk Often More Perceived Than Real) • Health & Safety of Occupants • EPA, ITRC, & State Guidances • ASTM New Phase 1 Standard • Attorneys & Citizen Groups • Future Liability

  4. When to Worry About VI? • If VOC Contamination & Structures Exist: • Laterally within 100’ (EPA, DTSC) • Vertically Within 100’ (EPA, DTSC) • NY: No Limits!!! • Complaining Occupants • Structures With Odors, Wet Basements • Sites With Contamination & Future Use • Attorneys & Communities • Even Animals, Fruits, Vegetables

  5. Tier 1: Primary Screening Q1: VOCs present? Q2: Near buildings? Q3: Immediate concern? Tier 2: Secondary Screening Q4: Generic screening Q5: Semi-site specific screening (alphas from charts & tables) Tier 3: Site-Specific Pathway Assessment Q6: Indoor air (and/or subslab) EPA-OSWER Draft Guidance

  6. Newest Changes (2010?) EPA OSWER VI Guidance Tier 1: Primary Screening Q1: VOCs present? Q2: Near buildings? Q3: Immediate concern? Tier 2: Source Screening Generic screening using near-source samples Tier 3: Pathway (Building) Assessment Multiple lines of evidence (sg & gw) Must go inside???

  7. EPA Guidance Updates • Fed EPA (OSWER & Superfund) • Modeling no longer an exit • Moving to sub-slab & indoor air • 7 to 30 day indoor air sampling period • Att factor of 0.1 for SG & 0.001 for GW • Decision matrix? • EPA-OUST: Guidance for HCs by 2012 • Exclusion criteria by Fall 2010

  8. OH 9-07

  9. Allowable Benzene in GW 1e-6 risk • New OSWER Guidance: 0.31 ug/m3/0.001 = 0.31 ug/L/0.2 = 1.5 ug/L • Robin Davis’ Exclusion Value: 1000 ug/L ~700 times lower than database suggests!!

  10. Allowable Soil Gas Levels(Benzene 1e-6 Risk, residential)

  11. State Guidance Updates • States With Recent Guidances/Policy • OR, OH, MT, WA • States Rethinking Guidances/Policy • IL, NJ, MA, MO, TN, ME, CA

  12. CA Agencies • CA-DTSC (& LA-RWQCB) • Soil Gas, VI, & Mitigation “Advisory” • CHHSLs (thanks to OEHHA) • EPA Region 9 • Follows the EPA Draft VI Guidance • Adopted Region 3 Screening Levels • SF-RWQCB • ESLs include aliphatics! • Central Valley Boards • Want Residential Criteria Applied Regardless of Site Use

  13. Uh-Oh E-mail received on 9/15/09: Iwanted to provide a heads up that R2 (SF) is poised to modify its Environmental Screening Levels (ESLs) with respect to the vapor intrusion pathway ... the consequence of this change would be much lower groundwater ESLs for this pathway (20 to 30x lower for most VOCs and over 200x lower for biodegradable VOCs such as BTEX) ... details below ... cheers

  14. ITRC VI GUIDANCE • Practical How-to Guide • Stepwise Approach • Investigatory Tools (Toolkit) • Thorough Discussion of Mitigation • Scenarios Document • Three Training Dates in 2010

  15. The Net Widens: ASTM VI Standard • Focus on Property Transactions • Prescriptive Screening Distances • No RBSLs (RBC) • No Assessment Recommendations • Legal Standards • Mitigation • Released March 3, 2008

  16. ASTM VI Standard Vapor Intrusion Condition (VIC) is defined as “the presence or likely presence of any volatile chemical of concern in existing or planned structures on a property resulting from an existing release or a past release from contaminated soil or groundwater on the property or within close proximity to the property, at a concentration that presents or may present a human health risk.”

  17. OH 9-07

  18. Liability Concerns • Phase I Environmental Consultant • Prospective/Current/Past Property Owner • Property Lender • Property Insurer

  19. Regulatory Approach for HC Sites Current Regulatory Approaches: USEPA: Guidance not recommended for UST sites ASTM: Screening distance reduced from 100’ to 30’ Some agencies include a 10X biodegradation factor ITRC: Use vertical profile to demonstrate Data suggests these approaches are overly conservative for most petroleum release sites

  20. Methods to Assess VI • Indoor Air Sampling • Groundwater Sampling • Soil Phase Sampling • Predictive Modeling • Measure Flux Directly • Soil Gas Sampling • Supplemental Tools/Data

  21. Ingredients for Effective VI Assessments • Investigatory Approach • Determine Correct Screening Levels • Sample & Analyze Properly • Know & Use Supplemental Tools • Demonstrating Bioattenuation

  22. Some Key VI Assessment Issues • Experience of the Collector/Consultant • Have they done this before? • Do they understand RBSLs? • Quality/experience of field staff? Sr or Jr? • Get Enough Data Near/Around/Under • Legal Perspective • How conservative to be or not be?

  23. Most Common VI Bloopers Unit Confusion: • Assuming ug/L equivalent to ppbv • Assuming ug/m3 equivalent to ppbv • Vacuum units: in Hg to inches H20 Screening Levels: • Comparing to CHHSLs • Not calculating correct levels

  24. Approach Generalizations • Indoor Air • Always find something • Multiple sampling rounds: extra time & $ • Groundwater Data • Typically over-predicts risk • Soil Phase Data • Typically not allowed; over-predicts risk • Soil Gas Data • Transfer rate unknown • Sub-slab intrusive

  25. Indoor Air Measurement • Pros: • Actual Indoor Concentration • Cons: • Where From? • Inside sources (smoke, cleaners) • Outside sources (exhaust, cleaners) • People activities – NO CONTROL! • Time-intensive protocols • Snapshot, limited data points • Expensive!!

  26. Ambient Air Benzene at 23 CA Sites

  27. Indoor Air Consumer Products Containing PCE PCE Concentration Product ARAMCO Art and Crafts Goop Not Specified Aleenes Patio & Garden Adhesive 70% Gumout Brake Cleaner 50 - 90% Liquid Wrench Lubricant w/ Teflon 65 - 80% Plumbers Goop Adhesive 67.5% Hagerty Silversmith Spray Polish 30.5% Champion Spot it Gone 20 - 25% Wide variety of consumer products still contain high concentrations of PCE. KEY POINT:

  28. New Indoor Source of 1,2-DCA DETECTION FREQUENCY CONCENTRATION Median 1,2-DCA Conc. 90%ile 1,2-DCA Conc. 1,2-DCA Detection Frequency (%) 1,2-DCA Concentration (ug/m3) USEPA INDOOR AIR LIMIT <0.08 <0.08 <0.08 Indoor concentration of 1,2-DCA increasing over time. New indoor source = molded plastic (e.g., toys, Christmas decorations). KEY POINT:

  29. OH 9-07

  30. Passive Soil Gas Samplers Adsorbent inside badge Adsorbent inside tube open on one end Adsorbent inside vapor permeable, waterproof membrane

  31. Approach Generalizations • Indoor Air • Always find something • Multiple sampling rounds: extra time & $ • Groundwater Data • Typically over-predicts risk • Soil Phase Data • Typically not allowed; over-predicts risk • Soil Gas Data • Transfer rate unknown • Sub-slab intrusive

  32. Modeling • Johnson-Ettinger Most Common • GW, soil, soil gas spreadsheets • Screen & advanced versions • EPA-OSWER: no longer an exit • Biovapor • Includes bioattenuation • Agency acceptance?

  33. O2 HC Conceptual Model What is BioVapor? Version of Johnson & Ettinger vapor intrusion model modified to include aerobic biodegradation (DeVaull, 2007). 1-D Analytical Model SIMPLE MATH Oxygen Mass Balance Uses iterative calculation method to account for limited availability of oxygen in vadose zone. Simple interface intended to facilitate use by wide range of environmental professionals. User-Friendly Free, easy-to-use vapor intrusion model that accounts for oxygen-limited aerobic vapor intrusion. KEY POINT:

  34. aerobic zone BioVapor – API 1-D Steady State VI Model 3 Advection, diffusion, and dilution through building foundation 2 Diffusion & 1st order biodegradation in aerobic zone Oxygen 1 Diffusion only in anaerobic zone anaerobic zone Hydrocarbon Algebra Solution for:Oxygen demand = Oxygen Supply Vapor Source

  35. Which Soil Gas Method? • Active? • Passive? (limited use) • Flux Chambers? (limited use) Active method most often employed for VI

  36. Probe Considerations • Tubing Type • Rigid wall tubing ok (nylon, teflon, SS) • Flexible tubing not (tygon, hardware store) • Small diameter best (1/8” or ¼”) • Probe Tip • Beware metal tips (may have cutting oils) • Equilibration Time • Effects by air knife, rotary, air percussion, sonic • Equipment Blanks • Need to collect blank through collection system

  37. Soil Gas Sampling Issues • Sample Size • Greater the volume, greater the uncertainty • Smaller volumes faster & easier to collect • Containers • Canisters: More blank potential. Higher cost • Tedlars: Good for ~2 days. Easier to collect • Flow Rate • Really not imp. But most agencies < 200 ml/min • Tracer/Leak Compound • Crucial for sub-slab & larger sample volumes • Gases (He, SF6, Propane) & Liquids (IPA)

  38. Beware of the Hardware

  39. Poor Hardware

  40. Container Issues Large vs. mini-canisters Filling a tedlar bag with syringe

  41. Common Soil Gas Analyses • VOCs • Soil & Water Methods: 8021, 8260 • Air Methods: TO-14, TO-15, TO-17 • Hydrocarbons • 8015 m, TO-3 • Oxygen, Carbon Dioxide • ASTM 1945-96 • SVOCs (sorbent methods) • Air Methods: TO-4, TO-10, TO-13

  42. On-site TO-15 Scan/SIM • Simultaneous Scan/SIM mode enables < 10 ug/m3 for All VOCs & ~ 1 ug/m3 for subset of compounds. • Only 2cc of Sample. Eliminates Hardware • Real-time Analysis in Structures: Control! • Two “Mobile Air Labs” Now Operational • Can Go Into Automated Mode

  43. Don’t Forget 8021 • Can get to 1 ug/m3 for TCE, CCl4, PCE • Can get to ~25 ug/m3 for Benz & Napthalene • 5 minute run time for benzene, TCE & PCE • Cost ~ 1/5 of TO-15

  44. Supplemental Tools/Data • Site Specific Alpha Using Radon • Factor of 10 to 100. $100/sample • Indoor Air Ventilation Rate • Factor of 2 to 10. <$1,000 per determination. • Soil Physical Properties • Moisture content the key parameter • Real-Time, Continuous Analyzers • Can sort out noise/scatter

  45. Soil Gas Sampling for HCs • Might Need to Sample <5’ bgs • If samples >5’ bgs exceed allowable levels • How to know? On-site analysis best • If not, collect samples anyway • Always Collect Oxygen Data • Might Need Soil Phase Data

  46. ? Sub-Slab vs. Near-Slab Samples

  47. Dirty Groundwater (>100 ug/l) at Site

  48. Dirty Soil (>1 ppm) at Site

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