Vapor Intrusion Assessment. Kaitlyn S. Rhonehouse, P.E. Florida Brownfield Association 16 th Annual Conference, Brownfields in Motion

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1 Vapor Intrusion Assessment Kaitlyn S. Rhonehouse, P.E. Florida Brownfield Association 16 th Annual Conference, Brownfields in Motion

2 VI Assessment what to consider? Potential for VI Phase I ESA ASTM E1527 Revision How VI addressed Investigation triggers VI Regulatory Guidance Update Sampling Techniques

3 Phase I ESA Considerations CERCLA Liability Protection/AAI ASTM Phase I ESA E satisfies AAI E did not mention vapor migration/intrusion E revised vapor migration clarified as included in Phase I ESA Anticipated publication late 2013 EPA rule update to follow - recognizes E as AII-Compliant

4 Vapor Migration Vapor migration clarified: migration refers to the movement of hazardous substances or petroleum products in any form, including, for example, solid and liquid at the surface or subsurface and vapor in the subsurface. E referenced document Vapor encroachment screening guide Provides industry consensus methodology to assess vapor migration Not required for AAI compliance Evaluating the potential for vapor migration not vapor intrusion

5 Vapor Intrusion Guidance EPA Final Subsurface Vapor Intrusion Guidance Draft guidance (OSWER Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils) published in 2002 Public comments in 2011 and 2012 Final guidance (external review draft) released April 2013 for public input Intended to be a unified guidance for use by RCRA, CERCLA, Brownfields, and States Framework for assessing VI by collecting/evaluating multiple lines of evidence to support risk management decisions Preliminary analysis Detailed investigation (sampling/modeling)

6 Vapor Intrusion Guidance 2002: OSWER Screening Level Tables 2013: VI Screening Level Calculator Exposure Scenario TCE MCL

7 Usual Suspects Volatile? Toxic? VOCs/solvents Drycleaners (CVOCs/solvents) Manufacturing and chemical processing plants TRPH/BTEX Gas Stations LUSTs Coal Gasification Plants Methane/Hydrogen sulfide Landfills Natural Gas lines

8 A Problem for Florida? Florida No Guidance yet. FDEP (Rob Cowdery) gave update at FBA in 2010 State guidance and risk-based exposure levels were expected in 2011; currently no approval for funding new regs Change in administration? Conditions favorable for VI in many locations in FL Shallow water table High groundwater temperature Several FDEP GCTLs trigger exceedance of indoor air screening level (e.g. TCE, VC, xylenes) Possible effects of FL VI regulations: reopening sites with conditional closures or long term NAM to evaluate VI; need for vapor mitigation systems Better to address VI now?

9 Indoor Air Sampling DO NOT sample indoor air as a first step Studies have shown detectables where no subsurface contamination present If you must then perform pre-sampling survey Must consider: Other indoor/outdoor sources: active drycleaners, aerosols, mothballs, insect repellants, air fresheners, nearby industrial facilities Building design/construction: new materials, basement, HVAC Meteorology: temperature, precipitation, wind, barometric pressure May ultimately be needed to confirm modeling or soil gas data

10 Indoor Air/Soil Gas Sampling VACUUM Summa Canister Evacuated canister Flow controller Samples to be collected over a period from 1 day to 1 week long PASSIVE Waterloo Membrane Sampler Passive permeation sampler Time-weighted average concentrations of vapors Small size, easy to deploy, lower cost

11 Soil Gas Sampling Vapor Implants Stainless steel screen Inserted at depth in borehole Verify purging rate, vacuum, volume purge, absence of annular leakage (able to be replicated?) Probe/Summa Canister Inserted through hole drilled in slab Shroud around probe filled with tracer gas Analyze sample for tracer to confirm seal

12 Mathematical Models Johnson and Ettinger, 1991 J&E Model: Steady-state upward diffusion from an underlying source Intrusion through a perimeter crack Source could be soil, soil gas, groundwater, or NAPL Generally conservative but beware of misapplication

13 Summary E : Need to consider vapor migration during Phase I ESA E or other vapor encroachment screening method VI risk factors to trigger investigation: Vapor forming/toxic chemicals? Building? No Florida guidance could be on the horizon EPA Final VI Guidance Evaluate multiples lines of evidence/data Soil, groundwater, soil gas, indoor air, modeling VI Screening Criteria Calculator VI Issue: now what??

14 How to Mitigate Vapor Intrusion