Vapor Intrusion: The Conference An Analytical Perspective

Transcription

1 Vapor Intrusion: The Conference An Analytical Perspective January 23-24, 2014 Tod Kopyscinski

2 TABLE OF CONTENTS What is Vapor Intrusion Analytical Methods Air Sampling Hardware and Procedure Analytical Equipment Canister Cleaning and Certification Additional Sampling Information Questions? 2

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4 WHAT IS VAPOR INTRUSION Vapor Intrusion (VI): The migration of volatile chemicals from the subsurface into overlying buildings (EPA, draft VI guidance, 2002). The VI Pathway may pose unacceptable risks of longterm exposure via inhalation of chemicals present in indoor air resulting from VI. A complicating factor for VI investigations is the common presence of those same volatile chemicals within buildings unrelated to VI ( background levels ). 4

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6 ANALYTICAL METHODS TO-14 (39 Compounds) For the analysis of chlorinated solvents as wells as BTEX compounds Older Method TO-15 (62 Compounds) Includes all To-14A compounds plus water soluble Newer Method New Technology TO-17 (Tube) Tube Method Thermal desorption technique Similar list to TO-15 MADEP APH (Air- Phase Petroleum Hydrocarbons) The MA method for determination of BTEX, Naphthalene, 1,3- Butadiene and 3 hydrocarbon ranges. Applicable for petroleum products such as gasoline, volatile fractions of mineral spirits, Kerosene, #2 diesel fuel oil, jet fuels and certain petroleum naphtha's. 6

7 ANALYTICAL METHODS Tentatively Identified Compounds (TICS) Using our database of approximately 100,000 compounds to help identify all other unknowns in an air sample. Suitable with all GC/MS methods TVOC Total Volatile Organic Compounds Calculated total of all volatiles present in the sample. Calculated using a similar expected like compound Toluene, Hexane, Chlorinated Solvent TO-13 (PAH s / Semi Volatile Compounds) PUF Method Polyurethane foam and XAD Applicable for polyaromatic hydrocarbons and other semi volatile compounds 7

8 MORE ANALYTICAL METHODS EPA Method 3C Modified (Fixed Gases) Helium leak test (can t be analyzed by TO-15) Analysis can include N2, O2, CO, CO2, CH4 Other compounds can be done by request as well Radiello or other Passive Technique Passive technique for the collection of volatiles Longer term exposure up to 30days Thermal or chemical desorption Custom Analysis Unique compounds of concern Lower limits 8

9 6 L Summa Canister 400 cc minican Thermal Desorption Tube Tedlar Bag

10 MORE SAMPLING MEDIA 400cc 6 liter 1 liter 1 liter 1.4 liter 3 liter 10

11 CANISTER SIZE DEPENDS ON REQUIRED DETECTION LIMITS & SAMPLING TIME Sub-PPB / low PPT for ambient air analysis (TO-15) requires large sample sizes (1L) and therefore large canisters. Standard injection volumes are 400cc. Low PPB-PPM analysis requires small sample sizes (0.1 to 20 cc) and therefore smaller canisters can be used. 6L Canister 0.4L MiniCan PPT PPB PPM % 11

12 FLOW CONTROLLER 12

13 SAMPLING WITH SUMMA CANISTERS Minican flow controller Types of flow control Flow controllers Restrictor Restrictor with gauge 13

14 MORE FLOW CONTROLLERS 14

15 FLOW CONTROLLER DESIGN AND PURPOSE The flow controller maintains a constant sample flow rate over the integrated time period, despite changes in vacuum and temperature. 15

16 PAH S / TO-17 AIR SAMPLING PAH s are sampled on a PUF (polyurethane foam) cartridge. Low volume pumps are used for sampling. TO-17 samples can also be taken using the same pumps. 16

17 PASSIVE SAMPLING Diffusion sampling High adsorbent capacity Predictable uptake rates Solvent/chemical desorption / Thermal desorption Long sampling times up to 30 day sampling time 17

18 PROJECT MANAGEMENT Below is a list of vital information needed: Application Soil gas, indoor air Required RL s What reporting limits will be needed Canister size Sampling duration Compound list What type of canister certification required Connections, tubing and/or fittings needed Documentation: COC Chain of custody Canister and flow controller ID s Start and stop times Start and stop vacuum Flow rates for tube sampling Information on levels High level samples 18

19 REQUESTING/ORDERING AIR MEDIA Summa canister orders are much different than standard environmental water and soil bottle orders. Please allow ample time for media preparation when able. Summa Canister Preparation: Clean Canisters Clean flow controllers Certify canisters or entire sampling train Calibrate flow controllers Leak check sampling train Document Pack and ship 19

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21 SAMPLING WITH SUMMA CANISTERS Soil Gas Sample: Sampling outside under the ground surface. Recommended flow rates of less than 200cc/min. For example a 6 liter canister would take 30 minutes to fill and a 1 liter canister would take 5 minutes. Sub Slab Sample: Sampling inside through the slab / foundation. Recommended flow rates of less than 200cc/min. Ambient / Outdoor Sample: Sampling outside as a blank or background. Indoor Air Sample: Sampling indoor living spaces 21

22 SAMPLING WITH SUMMA CANISTERS Grab Sample: Canister fills in seconds with no restriction, filter only Restricted Grab Sample: Canister fills in minutes with critical orifice and filter. Regulator Integrated Sample: Canister fills at a constant rate usually over 1 hr. to 72 hours without using power to find average VOC concentration 22

23 SAMPLING WITH SUMMA CANISTERS Critical Orifices are Useful for Short Term Constant Flow Sampling to 1/2 Atmosphere F L O W V1 V2 V3 V4 25% 50% 75% 100% TIME 23

24 SAMPLING WITH SUMMA CANISTERS Determination of True Average Concentrations Requires Constant Flow F L O W V1 V2 V3 V % TIME 24

25 SAMPLING WITH SUMMA CANISTERS Sub Slab and Soil Gas Leak Check 25

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27 ANALYTICAL EQUIPMENT GC/MS Separates and detects Concentrator Concentrates and cleans up sample aliquot Dynamic Diluter Dilutes samples and prepares standards Auto Sampler Holds samples Data System Controls entire system 27

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29 TYPES OF CANISTER CLEANERS 29

30 CANISTER CLEANLINESS All Canisters go through an extensive cleaning process which includes: Heating to a minimum of 100 C to help remove sticky compounds Flushing with ultra high purity air/nitrogen Evacuation with a molecular drag pump to pull down to a final pressure of less than 50 mtorr One canister from each cleaning batch is tested by EPA T0-15 to ensure that it is contaminate free Regulators cleaned with ultra pure nitrogen 30

31 CANISTER CLEANLINESS Certification: Three levels of Quality Assurance Batch Certified One canister in a Batch is analyzed, if clean all are considered clean. Individually Certified All canisters are analyzed and proven clean. Individually Certified Sampling Trains The entire sampling train(canister and flow controller) is analyzed and proven clean. Certification requires a full TO-15 analysis 31

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33 CONVERTING ANALYTICAL RESULTS Formulas are Compound Specific ppbv = (μg/m³ X 24.45)/ MW μg/m³ = (ppbv X MW)/ MW = Molecular weight of the compound = Gas constant The MW of Benzene is 78 (25 μg/m³ X 24.45)/ MW(78) = 7.8 ppbv The MW of TCE is 131 (25 μg/m³ X 24.45)/ MW(131) = 4.7 ppbv 33

34 WHY ARE MY REPORTING LIMITS ELEVATED? Limited sample volume; Canister not full, canister too small If normal injection volumes (i.e., cc) result in a RL of 0.05ppbv, using half that amount (200 cc) will double the reporting limit to 0.1ppbv. High concentration of one or more target compounds and/or non target or matrix interference; If toluene is detected in a sample at 10ppm, we will not be able to see benzene at 0.05ppbv. 10ppm is 100 times above our instrument calibration (100ppb). In this case, we would analyze the sample at a 100 times dilution to obtain a value of 100ppbv off the instrument. This would result in the RL of benzene to be 100 times higher as well (<5ppbv). 34

35 CHROMATOGRAM OF UNRESOLVED COMPLEX MIXTURE OVERLAID WITH LOW STANDARD 35

36 AIR SAMPLING Common VI Issues Leaks Clogs Matrix Interferences Dilutions Valves Tubing Connections Controllers Dirt Dust Grit Water High nontarget compounds Water CO2 Elevated reporting limits 36

37 SAMPLING Common VI Issues Compound list Must be known prior to sampling Soil matrix/porosity Clay/compact soil can restrict flow Tubing type Contamination Connections 37

38 Any questions? Tod Kopyscinski Con-Test Analytical Laboratory 39 Spruce Street East Longmeadow, Ma