Part 4 - Methods to Assess VI. Factors Complicating VI Assessments. Ingredients for Effective VI Assessments

Transcription

1 Part 4 - Methods to Assess VI Groundwater Sampling Soil Phase Sampling Predictive Modeling Indoor Air Sampling Supplemental Tools/Data Soil Gas Sampling Part 5 Factors Complicating VI Assessments Ultra Low Screening Levels Increases chances for false positives Inconsistent Screening Levels Allowed Assessment Methods Vary among agencies Chlorinated vs. Petroleum Hydrocarbons Treat same way? Allow for bioattenuation how? Ingredients for Effective VI Assessments Choose Investigatory Approach Determine Correct Screening Levels Sample Properly & Efficiently Analyze Properly Know & Use Supplemental Tools 1

2 I Know You Want to be Billable, but Enough Experience? Collector done soil gas before? Lab certified for methods? Regulator Public YOU! (Do you & staff really have it?) Hire Expertise First Few Times Lines of Evidence Chemistry (GW, SG, SS, IA) Soil Physical Properties Modeling Building Construction & Ventilation Temporal Patterns Biodegradation Multiple lines of evidence often needed to assess pathway Groundwater Data Preexisting Data Often Exist Over proper well screen interval? Coverage typically limited; interpolation Gather New Data Well location, construction, sampling Might miss actual contamination zone Perched/clean water layer? Likely Will Over-Predict VI Risk For HCs 2

3 Most Points Fall Below Henry s Predicted Values Soil Phase Data Soil data generally not acceptable in VI Assessment Existing soil data line of evidence Can screen in sites Cannot be used alone to screen out sites Convert to soil gas concentrations Partitioning equations exist. Likely overestimate. Likely OK for Petroleum HCs Measured Soil Gas Data vs. Predicted from Soil Phase Data Measured F1 in Soil Vapour (mg/m 3 ) 1.E+07 1.E+06 1.E+05 1.E+04 1.E+03 1.E+02 1.E+01 1.E+00 1.E-01 1.E-02 Difference depth soil gas & soil > 0.5 m Vm/Vp 50th = 2.1E-5, 90th = 3.6E-3 Difference depth soil gas & soil < 0.5 m Vm/Vp 50th = 9.3E-5, 90th = 7.4E-3 1:1 1:10 1:100 1.E-02 1.E+00 1.E+02 1.E+04 1.E+06 Predicted F1 in Soil Vapour (mg/m 3 ) CPPI Database Measured vapor concentrations 10 to 1000x less than predicted 3

4 Predictive Models Pros: Can Use GW, Soil (?), Soil Gas Data Relatively Easy Cons: Many agencies no longer allowing use Which Version to Use? No Validation Erroneous Conclusions Can Tweek to Your Pleasure Johnson and Ettinger Model D T eff = overall effective diffusion coefficient [cm 2 /s] D eff crack = effective diffusion coefficient through cracks in foundation [cm 2 /s] C vs = vapor concentration at the source [g/cm 3 ] C indoor = indoor air concentration [g/cm 3 ] L T = distance from source to basement [cm] A B = cross-sectional area of foundation available for vapor flux [cm 2 ] Q soil = volumetric flow rate of soil gas into the building [cm 3 /s] L crack = thickness of the foundation [cm] A crack = area of cracks or openings through which vapors enter building [cm 2 ] Q B = building ventilation rate [m 3 /s] = the crack factor : A crack /A B so that 0 =< =< 1 Model Assumptions One-dimensional vertical transport Steady state conditions No preferential pathways Uniform mixing within building Slab on grade or basement construction No biodegradation Constant source concentration Prior to using model results, you need to ensure that model assumptions and site conditions are consistent Slide courtesy of ITRC 4

5 Which Model & Version to Use? Johnson & Ettinger most common 2001 to 2003 GW, soil, soil gas spreadsheets Screen & advanced versions September 2017 Biovapor (API) Incorporates bioattenuation PVI-Screen (EPA-ORD) Includes uncertainty analysis Just released to public EPA 2017 J-E Model BUGS: Ventilation rate changes risk for soil gas data, but not sub-slab data. TCE SL: 100 ug/m3; 16 ug/m3 from VISL Code writer & contact person for technical support no longer at EPA!! How Well Does J-E & VISL Predict? (From GW & Soil Data) Hydrocarbons Calculated SG value too high by x No bioattenuation (10 to 1000x reduction) Over Predicts in All Cases Chlorinated Solvents Deep Source Calculated SG value too high by x Over Predicts in Almost All Cases Chlorinated Solvents Surface Source Calculated SG value too low by x Under Predicts in Almost All Cases 5

6 What is BioVapor? 1-D Analytic al Model Oxygen Mass Balance User- Friendly Version of Johnson & Ettinger vapor intrusion model modified to include aerobic biodegradation (DeVaull, 2007). 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. SIMPLE MATH O 2 HC Free, easy-to-use vapor intrusion model that accounts for oxygen-limited aerobic vapor intrusion. Indoor Air Measurement Pros: Actual Indoor Concentration Cons: Limited data points Can be expensive!! Where are the compounds coming from? Vapor Intrusion Outside Sources (i.e. exhaust) Inside sources (i.e. household items) People s activities NO CONTROL! Most Agencies Require Min 2 Sampling Rounds!! Ambient Air Temporal Trends California Air Resources Board - Benzene Parts per billion th Percentile Mean Detection limit Ambient (outdoor) air quality has greatly improved over the last decade 6

7 VOCs in Indoor Air From USEPA BASE study Minimum, maximum, 5, 25, 50, 75, 95th percentiles From: Girman, J. Air Toxics Exposure in Indoor Environments, EPA Workshop on Air Toxics Exposure Assessment, IA Sampling in Occupied Spaces Ambient Air Unexpected Sources Difficult to interpret the source of contamination found in indoor air results Vapor Intrusion Be aware of unexpected sources of Petroleum Hydrocarbons and Chlorinated Solvents in indoor air Example of an Unexpected Source: Bloonies Banned in Australia & NZ due to known toxicity levels however, can still be found in America, usually in the cereal isle! Compound Bloonies Yellow Bloonies Red Cancer Noncancer (µg/m 3 ) (µg/m 3 ) 1,2,4-Trichlorobenzene - 8,400 n/a ,2,4-Trimethylbenzene 1,700 - n/a ,3,5-Trimethylbenzene 1,100 - n/a n/a Benzene 960 1, Ethylbenzene 1, , Toluene 1,300 5,000 n/a 5, Xylenes 3,800 15,900 n/a

8 Disclaimers H&P is NOT a product testing company. H&P is NOT accusing any company of any wrongdoing; as far as we know, all of the companies that produce these products are in compliance with the regulations that apply to their industry. No claims about any brands are being made and any likeness to particular brands is unintentional. While we made an effort to collect blank QC samples and to collect and test these products in a controlled environment, simply put, we squeezed/squirted/poured about 1-2 ml of these products into 40mL VOA vials and analyzed the headspace a few days/hours/minutes later. All screening values are per EPA RSLs Nov 2013 All values in this presentation are reported in µg/m 3 Fish Oil Vitamins Heart Health x 2 = 2,400 mg Broke open (2) pills, squeezed the supplement into the VOA, dropped in both capsule casings, and closed the lid. Compound Fish Oil Cancer (µg/m 3 ) 1,3-Butadiene Benzene Shoe Closet Casual Shoes C5-C8 Aliphatics Sport Shoes C5-C12 Aliphatics C6-C8 Aromatics Ethylbenzene, Xylenes Polish/Waterproofing C5-C12 Aliphatics Trichloroethene 1,3 Butadiene Compound Shoe Polish/ Waterproofing Cancer (µg/m 3 ) Noncancer (µg/m 3 ) Trichloroethene ,3-Butadiene TCE Short Term Exposure 2 ug/m3 for only 24 hours during first trimester 8

9 Natural Gas Compound NG CC NG NN NG SB NG HT NG EW Cancer (µg/m 3 ) Noncancer (µg/m 3 ) Benzene 470 2, , Cyclohexane 1,300 1, , n/a 6, Ethylbenzene , , m,p-xylene , n/a n-heptane 1,000 5, , n/a n/a n-hexane 3,100 7,600 1,700 76, n/a o-xylene , n/a Propene 21,000 56, n/a 3, Toluene 380 2, , n/a 5, Methane & TPH yes yes yes yes yes - - Modeling Clay Compound Clay 1 Clay 2 Cancer (µg/m 3 ) Noncancer (µg/m 3 ) Tetrachloroethene Benzene Ethylbenzene , Toluene 13, n/a 5, Xylenes n/a ,2,4-Trimethylbenzene n/a 7.30 Two Types of Clay Tests performed because of confusion as to where PCE hits were coming from at a gas station? Lab contamination? Helium (Party Tank) We tested two kinds of party helium with <1% impurities. Compound Helium 1 Helium 2 Cancer (µg/m 3 ) Noncancer (µg/m 3 ) Benzene Ethylbenzene , Naphthalene 1 n/a TPH gas (C5-C11) n/a 600 n/a n/a 9

10 Silly String Soda Pop Pop? Yes. I am from the Midwest. Compound Soda Pop Cancer (µg/m 3 ) Noncancer (µg/m 3 ) (C5-C8) Aliphatics (C9-C10) Aromatics 1,000 n/a 3.10 (C9-C12) Aliphatics 16, Interesting Fact: It is a well studied fact that Benzene is in soda pop (combination of a benzoate preservative and citric acid, especially in warm/light conditions) Candles Melted and Unmelted Wax tested Organic Beeswax (unscented) One test with melted wax poured into a VOA. Another test with solid wax placed in VOA. Compound Candle Burn Candle Cancer (µg/m 3 ) Noncancer (µg/m 3 ) Benzene 7, ,3-Butadiene 2, Ethylbenzene , Naphthalene

11 Conclusion? Birthdays will kill you. Helium Balloons Modeling Clay Soda Pop Birthdays Benzene 32,283 ug/m3 Ethylbenzene 2,206 ug/m3 TCE 448 ug/m3 Candles Silly String +7,027,580 Total TPH +25 Naphthalene +2,000 1,3-Butidiene Squeeze Toy Bloonies Other Products Tested Dish soap Shampoo Fish Oil Vitamins Air Freshener Sunscreen Essential Oils Soda Pop No VOC paint Guess what? They ALL contained VOCs in the headspace. Conclusion: Communication is Key 1. Communication with occupants before/during the sampling event 2. Communication with the laboratory regarding analyte list and reporting limits 11

12 Occupants: Do s and Don ts for ONE DAY 24 Hour DON T Examples Don t have a birthday party Don t paint your walls Don t use air fresheners Don t park in the garage Event the most experienced environmental consultants may miss something Remember: Having a handle on occupant activities for one day is difficult, but manageable. Occupants: Do s and Don ts for A MONTH?! LONG TERM SAMPLING: The push toward 21 Day Air Sampling brings in a whole new set of considerations 21 Day DO Examples You can have ONE birthday party 21 Day DON TS: For 21 Days, no daily use products? Don t wash your hair Only do dishes once/week Absolutely no shaving How do you list everything? People s daily lives include chemicals of concern that can make it difficult to interpret data Conclusion: Communication is Key 1. Communication with occupants before/during the sampling event 2. Communication with the laboratory regarding analyte list and reporting limits 12

13 Laboratory: Project Analyte List Report a Full VOC list, or create a project specific list with your lab? Report as low as possible, or only as low as you need to achieve DQOs? Compounds detected in at least one of the 30+ products tested 1,2,3-Trichlorobenzene Carbon disulfide Isopropylbenzene (Cumene) sec-butylbenzene 1,2,4-Trichlorobenzene Carbon tetrachloride m,p-xylene Styrene 1,2,4-Trimethylbenzene Chlorobenzene Methyl tertiary-butyl ether Tertiary-butyl alcohol (TBA) (MTBE) 1,3,5-Trimethylbenzene Chloromethane Methylene chloride Tetrachloroethene (Dichloromethane) 1,3-Butadiene Cyclohexane Naphthalene Tetrahydrofuran 1,3-Dichloropropane Dichlorodifluoromethane (F12) n-butylbenzene Toluene 1,4-Dioxane Ethanol n-heptane Trichloroethene 2,2,4-Trimethylpentane Ethyl acetate n-hexane Trichlorofluoromethane (F11) 2-Butanone (MEK) Ethyl tertiary-butyl ether n-propylbenzene Vinyl acetate (ETBE) 4-Ethyltoluene Ethylbenzene o-xylene TPH gas Acetone Hexachlorobutadiene p-isopropyltoluene Low/Med Aliphatics Benzene Isopropyl Alcohol Propene Low/Med Aromatics In Summary Occupant Communication Communication with occupants regarding products to avoid and products to disclose before/during the sampling event is key Laboratory Communication Having a laboratory that can generate project specific analyte lists, proper RLs, and provide any additional sample information can be very helpful Long Term Sampling Considerations Depending on the DQOs, long term sampling may make it more challenging to see through the everyday consumer products and properly assess the VI issue Indoor Air Sampling Methods Evacuated Canisters Summa Canister with flow regulator Adsorbents with Pump Need a lot of pumps Passive Adsorbents Longer collection periods (7 to 30 days) 13

14 Canisters for Air Sampling Sizes: 1 to 6 liter Flow Controllers: Typically 8hr or 24hr Now up to 7 days Connections: Either threaded fittings or quick connect fittings Considerations when using Evacuated Canisters Sampling Duration? Consider exposure period Also consider access to building Canister Vacuum Readings At Start: -26 to -30 inches Hg At End: -10 to -1 inches Hg Hardware Issues Performance Filling at proper rate? Fittings Tight? Cross-threaded? Pen/marker type Don t use sharpies Prefer gauges on cans, not on flow chokes Certification Blanks from previous use? Where to Collect Indoor Air Samples 1 st Floor, Basements, Crawl Spaces Where on First Floor? Where people are the most? Where there are the most penetrations? In more than one location? Commercial Buildings? Where people are the most? Multiple floors? Elevators? Outdoors? Always collect at least one outdoor ambient air sample 14

15 Collection of Indoor Air Samples with Evacuated Canisters Day 1 Interview Conduct survey and questionnaire Day 2 Drop Off Prepare sketch of home Select canister location(s) Place canister, record initial pressure Open valve, record time Day 3 Pick Up Close valve, record time, final vacuum Conduct post-test questionnaire Ship canister(s) under COC to laboratory Long Term Air Sampling (i.e day sampling periods) EPA and CA Regulators leaning toward this approach for IA evaluations Pros: Provides an average concentration for a longer period of time Cons NO CONTROL over occupants Misses short term occurrences (i.e. TCE) Commercial settings Cannot simply turn off the collector at night Passive Sampling Media Hydrophobic Adsorbant provided by Beacon Environmental Adsorbent inside vial with membrane Adsorbent inside vapor permeable, waterproof membrane 15

16 Passive IA Method C = m/q*t * 1,000,000 C = concentration in ug/m 3 m = mass of analyte in ug t = exposure time in minutes Q = experimentally measured sampling rate (ml/min) Note: EPA Pushing for Longer Sampling Times Factors Influencing Passive IA Sampler Performance Environmental Temperature Relative Humidity Type of Sorbent Proper type for COC Proper for sample period Expected Concentrations High uptake samplers (axial) for low conc Low uptake samplers for high conc Supplemental Tools/Approaches Indoor Air Ventilation Rate Factor of 2 to10 Soil Physical Properties (Factor of 2 to 5) Site Specific Alpha Using Radon Factor of 10 to 100. $125/sample Building De-Pressurization Tests Isotope Ratios Indoor Air Grab Sample Snapshots Real-Time, Continuous Analyzers 16

17 Building Ventilation Rates ANSI / ASHRAE Standard Ventilation for Acceptable Indoor Air Quality Building Type USEPA Default (Residential) Office Space Supermarket Classroom Restaurant Air Exchange Rate (# / day) High Building Ventilation KEY POINT: Buildings designed for high density use will have high air exchange rates. Measured Attenuation Factors By Radon AF = C Indoor C Source Hill AFB Altus AFB USEPA Default USEPA Actual Sub-Slab to Indoor Air 8 x x x KEY POINT: For two test sites, USEPA default attenuation factors over-predict vapor intrusion by 100x x. VI Assessment Point #2: Building Depressurization 17

18 12 ug/m3 6 ug/m3 6 ug/m3 Source Determination Using Isotopes VI Assessment Point #3: Indoor Air Snapshots for Chlorinated Sites With Lots of Structures GC-PID/ECD Hapsite GC-MS Similar to EPA TAGA Approach 18

19 How to Cover So Many Units Effectively?? VI Assessment Topic High Resolution VOC Data The Fundamental Problem with VI Assessments & Remedies 19

20 Category: Song N E N N R Continuous Monitoring System Sample Inlets 12 High System Capability Fully Quantitative! Can Reach Ultra-Low Levels (<1 ug/m3) for TCE, PCE, vinyl chloride & others <10 min Analysis Time for TCE, PCE, VC Multiple Sample Locations (10 to 30) Operating Costs: Power plus N2 (<$15/mo) Very Stable stays calibrated for months Discrete Sample Mode Real-Time Data User Friendly Dashboard 20

21 Monitoring of Other Variables BP, Indoor pressure, Differential Pressure Wind Speed, temperature, other climatic Can Turn On-Off 115 V Relays 61 Monitoring/Response Platform Remotely Document: Raw Data Moving Average HVAC/Venting On/Off Recording User Friendly Web-Based Data 21

22 Short-Term TCE Assessment Options Time-Integrated Sample One number over sampling period No real-time feedback Costly if multiple rooms, multiple events Can t see the pattern Continuous Analyzers Can determine duration: hours? Days? Long Term Passive/Canister Can see the pattern! Day vs night? HVAC? Expedited VI Assessments Can see pattern within days Can determine if from VI or indoor source Can determine cause & effect How often above screening level Pattern = Opportunity 65 Previous Thinking of IA Values 80 Office Area (P2) ug/m PCE Run # Time (hours) 5 September

23 Shop Air PCE June 2014 Office Area (P2) 50 PCE Concentration (ug/m3) and Temperature (degrees Celcius) PCE PCE IA Data from First 24 hours 6/6/14 12:00 6/6/14 15:00 6/6/14 18:00 6/6/14 21:00 6/7/14 0:00 6/7/14 3:00 6/7/14 6:00 6/7/14 9:00 6/7/14 12:00 6/7/14 15:00 6/7/14 18:00 6/7/14 21:00 Sample Date/Time Print Shop Air - PCE June 2014 Office Area (P2) ug/m PCE Run # Typical Data After 14 Days 80 Office Area (P2) ug/m3 40 PCE ug/m Run # 23

24 Temporal Variation SD Facility 500 Same Time Every Day ug/m tce Large Industrial Facility Definite Correlation with Differential Pressure Apparent Correlation with Barometric Pressure PCE Former Dry Cleaner BP WS 72 24

25 Former Dry Cleaner - Bathroom TCE Source Determination Manufacturing Facility 500 TCE TCE :00 pm 7:00 am 7:00 am 5:00 pm 5:00 pm Expedited VI Remedies Can try various remedies & see effects HVAC modifications Fans on/off Air filtration units Sealing sumps & cracks Especially Important for TCE Avoid Evacuating People! 75 25

26 Large Industrial Facility - SD SVE Remedial Confirmation Pre-SVE Active-SVE 5 days Proving the Effectiveness of a Remedy Remedy Evaluation - Home First 7 days Indoor Air Filtration Units Off 26

27 Remedy Evaluation - Home 30 days SSD Off Air filtration units off TCE Trailer 1 st Floor Trailer 1st Floor Filters On Filters Off 20 TCE Location 1 Location 2 Outdoor Temperature 27

28 Expedited Remediation Remedies Remediation & Mitigation System Monitoring In-Situ GW/Soil Remediation Thermal Heating Sub-Slab Depressurization Systems 82 Remediation Monitoring Vinyl Chloride Effluent Location EF 1 Vinyl Chloride 73 ug/m3 60 Vinyl chloride (ug/m3) Energized Before Energized 0 2/27/ Run # 3/11/ /21/ Expedited Source Identification Identify VOC Entry Points Source from VI vs Indoor Unexpected VOCs Superior to Hapsite Screening Much more data collected over time More robust; less downtime No more expensive 28

29 18 16 VOC Entry Point Determination Room 103 Indoor Air TCE (ug/m 3 ) Door Opened 8:00 am ug/m Room Closed:17: hours Door Closed 8:20 am Time Summary High Resolution Data Allows Pattern Pattern = Opportunity Opportunity to: Indoor vs Subsurface Source VOC entry locations, preferential pathways Determine Best Remedy Quickly!! Effectiveness of mitigation systems Effectiveness of remediation systems 29