Ask The Expert Webinar Series Vapor Intrusion Assessments Part Two: Improving Data Quality Using Today s Best Practices for Sample Analysis

Transcription

1 Ask The Expert Webinar Series Vapor Intrusion Assessments Part Two: Improving Data Quality Using Today s Best Practices for Sample Analysis Taryn McKnight Client Relations Manager

2 The migration of volatile chemicals from the subsurface into overlying buildings.

3 Vapor Intrusion Timeline EPA Adds Subsurface Intrusion to the Superfund Hazard Ranking System EPA OSWER finalizes Vapor Intrusion Guidance 2015 EPA OUST and ITRC work to publish Petroleum Vapor Intrusion Guidance 2014 OSWER works to finalize 2002 Draft Vapor Intrusion Guidance 2013 ASTM D Standard Practice for Active Soil Gas Sampling ASTM E Standard Guide for Vapor Encroachment ITRC Publishes Vapor Intrusion Guidance NY Guidance, Re-opens 1400 NFR Sites OSWER replaces RCRA Redfield Rifle/CDOT J&E model States begin addressing Vapor Intrusion: MA, CT, CA Many States Publish VI Guidance 2008 EPA Publishes Attenuation Factor Database Many organizations are hard at work, updating and finalizing guidance and standards Final Guidance on Vapor Intrusion is published 2016 Addition of VI to HRS and current debate over short term TCE risk Modified from: M. Traister, O Brien & Gere

4 Final VI Guidance OSWER Publication OSW ER TECHNICAL GUIDE FOR ASSESSING AND MITIGATING THE VAPOR INTRUSION PATHWAY FROM SUBSURFACE VAPOR SOURCES TO INDOOR AIR FINALLY! U.S. Environmental Protection Agency Office of Solid Waste and Emergency Response June

5 Page 15, Table 1-2 Note important updates to Indoor Air Testing

6 Key Recommendation Highlights Limit analyses to chemicals of concern Section 6.4 Assess the VI pathway using multiple lines of evidence Sections 6.3, 7.1 & 7.2 Generally support the decision to collect indoor air data Section & Consider collecting multiple rounds of indoor air samples Section 7.4 Document objectives and methods in a VI workplan Section 6.2

7 Importance of a CSM and DQO s Considerations: Section 2.0 The CSM will help guide the DQOs Site conditions and historical data Compounds of concern & anticipated concentrations Screening levels being applied Involve the lab early on. Accept comment on SOWs and achievability of DQOs. A CSM integrates all lines of site-specific evidence into a three dimensional conceptualization of site conditions Section 2.0

8 Vapor Intrusion Concurrent Sampling Wind Effect Ambient Background Indoor sources: carpet, dry cleaned goods, air fresheners, glues, paint, solvents, paints, smoke, heating oil, K2. Other sources: Vapor Intrusion, Ambient Air Intrusion Vapors in Vapors out! Vapors In/Out Breathing Zone HVAC Sub-Slab Vadose Zone Water Table Contaminated Groundwater

9 Multiple Lines of Evidence

10 Indoor Air - Active/Passive Active Sampling Considerations Compounds of concern Screening Levels Litigious or high profile site? Passive Sampling Considerations Desire for long term monitoring Environmental conditions Target analyte list and RLs Per EPA: Collect indoor samples and compare with controls Sub slab, ambient, lines of sight and building evidence Passive samplers, their use may grow as a result of recent demonstrations that they can yield results comparable to those obtained using evacuated canisters. Section A potential shortcoming of indoor air is background

11 Sub Slab/Soil Gas Sub Slab Considerations Can be used to resolve indoor sources vs. a VI source Can be used to assess if the VI migration route is complete Can be used to assess the potential for VI risk Soil Gas Considerations Near source, it may provide an estimate of source vapor concentration Can be performed without entering the structure Per EPA: Collect multiple samples per building to address spatial variability and multiple rounds to address temporal variability. Section There may be substantial spatial variability in subslab soil gas

12 Leak Check Considerations Liquid (qualitative) or Vapor (quantitative) Tracer Gas Use of a shroud For quantitative measurements the volume of gas in the shroud must be measurable Field or Laboratory analysis Reporting limit requirements Estimated values if concentrations exceed calibration range Section a reliable seal of the annulus between the probe and the probe housing and leak testing for the seal are generally recommended

13 Shut-in Leak Test 1. Remove brass plug 2. Loosen FC fitting 3. Attached FC to Can 4. Finger tighten 5. ¼ turn with wrench 6. Attach brass plug to FC 7. Tighten with wrench 8. Open and close valve 9. Observe gauge reading

14 Field Quality Control Samples Field Duplicates Require the use of a T-fitting or Co-locator

15 EPA Indoor Air Screening Levels

16 Various State Guidance

17 Target Analyte Lists - Volatile? The primary focus of Vapor Intrusion = Volatiles Not everyone agrees what constitutes a VOC Additional compounds may include SVOCs Metals Pesticides/PCBs These methods require sorbent or filter methods TO-13A, TO-10A, 6010

18 U.S. EPA VISL Calculator From the new guidance: EPA developed VISLs for human health protection that are generally recommended, medium-specific, risk-based screening-level concentrations These VISLs calculated are based on: Current toxicity values selected considering OSWER s hierarchy of sources (EPA 2003). Physical-chemical parameters for vapor-forming chemicals. EPA-recommended approaches for human health risk assessment (EPA 2009c, 2014a) The VISLs include indoor air screening levels for chronic exposures, for cancer and non-cancer effects of vapor-forming chemicals.

19 Evaluating Screening Levels In Summary State or Federal? Soil gas or Indoor air? Residential or Commercial attenuation factor? Units? Target analyte list? EPA RSLs or State Limits Do limits exist for your matrix If not, what alpha factor will you use to calculate for them? Be careful of units! Will you limit the list and does it include non-volatiles?

20 Commonly Requested Methods VOCs: TO-15, TO-17 VOCs: Modified SW8260B Fixed Gases: ASTM D-1946 SVOCs/PAHs: TO-13A Hydrocarbons: TO-15, TO-3 Diesel Range: TO-17 Carbon Range Speciation: MA APH

21 EPA Method TO-15 FAQs: EPA Method TO-15 was written for the determination of VOCs in ambient air collected in specially-prepared canisters and analyzed by GC/MS at concentrations above 0.5 ppbv. Method TO-15 is appropriately applied to only a subset of the 97 Title III VOCs, therefore a standard TO-15 list was not established.

22 Considerations when using TO-15 Notify lab of the CoCs Report full list or short list Necessary reporting limits to meet project objectives Notify lab of expected concentrations Which tracer gas will be applied Understanding SIM vs. Full Scan Understanding batch vs. individually certified media

23 SIM vs. Full Scan SIM Selected Ion Monitoring the process by which the instrument method is limited to detecting selected ions Full Scan Spectra SIM Spectra

24 Media Certification and Management Canister Cleaning Evacuated, heated, pressurized w/ zero air Certification Batch or individual Leak free overnight leak check test required 1 or 6 liter Summa canisters? Determined by reporting limit requirements Soil Gas: 1L generally acceptable Ambient & Indoor Air: 6L only Flow Controller Certification: Cleaned & Performance checked

25 Gauges, Impact to Data? Initial Vacuum confirm sufficient vacuum is in the canister. Range will generally be Hg Final Vacuum confirm sufficient sample was collected. Range should generally be 10-0 Hg

26 What is TO-17? FAQs: EPA Method TO-17 was written for the sampling and analysis of VOCs in ambient air at concentrations between ppbv. Sorbent tube/thermal desorption/gas chromatograph Once the sample has been thermally desorbed, the analytical method is identical to Method TO-15. Advancements in technology, primarily the availability of new types of adsorbents and thermal desorption systems is what prompted the development of this method.

27 What is TO-17? Sample collection system is a multi-bed sorbent optimized to manage moisture interference and capture a wide range of compounds Adsorbents Weaker Strong Strongest TO-17 TO-15 Volatiles TO-13 Semivolatiles C3 C2 C12 C26

28 Considerations when using TO-17 TO-17 requires laboratory consultation Compounds of concern Expected concentrations (including moisture) Data Quality Objectives ~ Distributive sampling ~ Backup tubes ~ Calibration verification (pumps) ~ Temperature acceptance criteria ~ Reporting limit requirements

29 Summary Do not take samples unless you have some idea of what the data is going to tell you - Conceptual Site Model Define your data quality objectives up front, this will determine the appropriate containers, collection procedures and analyses Over communicate with your testing laboratory. Teamwork up front will ensure less discussion when you receive your data Data quality is a function of the whole process: the project set up, the field sampling protocols, and the analytical protocols

30 Ask The Expert Webinar Series Thank you for attending Vapor Intrusion Assessments Part Two: Improving Data Quality Using Today s Best Practices for Sample Analysis To submit a question, type it into the Questions panel in the GoToWebinar toolbar and click Send. If you have any additional questions for today s presenter you may submit them directly to: Please be sure to visit the Ask the Expert Webinar Series web page for other scheduled webinars at: To view a recording of this webinar session, please contact: info@testamericawebinars.com