Laboratory considerations for VI Investigations.

How pre-planning and understanding the process

equals informed decision making.

Will Elcoate

Alpha Analytical

The VI Challenge

Donald Rumsfeld Defense Department briefing 2002:

There are:

• known knowns; things we know that we know.

• known unknowns; things that we now know we don't know.

But there are also

• unknown unknowns; things we do not know we don't

know.’

1

Sources of Uncertainty

2

Site Knowledge / CSM

Data Collection Strategy

Location selection

Variability in concentration

Other Sources

Sampling procedures

Sample Integrity

Documentation

+

Laboratory

Media Integrity

Media Cleaning & Certification

Instrument Calibration

Sample collection

Quality Systems of the

Laboratory

=Uncertainty

Laboratory Considerations

Start with the Conceptual Site Model (CSM)

The CSM informs the investigator on the type, number and

compounds of potential concern (COPCs) for Vapor Intrusion

for further sample collection.

Chemistry Data should:

• Meet Guidance, (Generic EPA, State or site specific) Risk

Screening Levels

• Be generated by a State Certified or NLAP Accredited Laboratory

for the Air Method(s) and the COPCs

• Meet Project Data Quality Objectives,

3

Quality Assurance Project Plan

Fill data gaps identified in CSM development.

Quality Assurance Project Plan

Well documented process EPA & States have guidance:

• Problem Definition/Background

• Project / Task Organization

• Data Quality Objectives

• Sampling Design & Rationale

• Analytical Laboratory Requirements

• Data Review & Usability

• Reporting, Documents and Records

To improve is to change; to be perfect is to change often.

Winston Churchill

4

Typical Air/Vapor Analysis Methodology

VOC’s TO-15, Full Scan/SIM; MA DEP APH; PIANO extended HC’s

VOC’s by EPA Method TO-17, EPA Method 325

SVOC’s, PCB’s TO-10, PAH’s TO-13

ASTM Methods: Fixed Gas ASTM 1946 Fixed Gases & Methane

Industrial Hygiene Methods NIOSH / OSHA methods

Mercury NIOSH 6009

Field

HapSite GC/MS, PID (FID) Land Meters

20 https://products.inficon.com

Method TO-15

6

Selective Ion Monitoring (SIM)vs. Full Scan Mode

• Refers to mass spectrometer modes of operation

• Full scan detects ions present over range (29-260)

• SIM detects specific ions at specific intervals

• Advantages / Disadvantages

– SIM mode increases sensitivity 10-fold

– Cannot do library searches on unknown compounds (TICs)

– Can be susceptible to false positives

7

Typical Sites / Common Chlorinated Contaminates

Chemical CasNum

EPA-RA

ug/M3

EPA-VISL-

TIAC

EPA-VISL-

TSSGC

TO-15 Full

Scan

TO-15

SIM

Vinyl chloride 75-01-4 0.17 0.17 5.6 0.51 0.051

Trichloroethene 79-01-6 0.48 0.48 16 1.07 0.107

trans-1,2-Dichloroethene 156-60-5 0.79 0.079

Tetrachloroethene 127-18-4 11 11 360 1.36 0.136

Methylene chloride 75-09-2 100 100 3400 3.46 3.46

cis-1,2-Dichloroethene 156-59-2 0.78 0.079

Chloromethane 74-87-3 94 94 3100 0.41 0.078

Chloroform 67-66-3 0.12 0.12 4.1 0.98 0.098

Chloroethane 75-00-3 10000 10000 350000 0.53 0.053

Carbon tetrachloride 56-23-5 0.47 0.47 16 1.26 0.126

1,2-Dichloroethane 107-06-2 0.11 0.11 3.6 0.81 0.081

1,1-Dichloroethene 75-35-4 210 210 7000 0.79 0.079

1,1-Dichloroethane 75-34-3 1.8 1.8 58 0.81 0.081

1,1,2-Trichloroethane 79-00-5 0.18 0.18 5.8 1.09 0.109

1,1,1-Trichloroethane 71-55-6 5200 5200 170000 1.09 0.109

8

*EPA-RA: Residential Air Regional Screening Levels Criteria per Regional Screening Levels, November 2015.

Selective Ion Monitoring (SIM)vs. Full Scan Mode

9

Example of a Potential False Positive from Petroleum Sources using SIM

▪Cyclohexane isomer can

cause false positive for

chlorobenzene using SIM

analysis

▪Common ions 112 & 77,

retention time match

10

Flexibility of TO-15

Concurrent Data Acquisition in Full Scan & SIM Mode.

All data available for reporting. Typically calibrated for >70

Compounds.

Concurrent acquisition gives confidence in QC.

Option for “Matrix interference” to meet Screening Levels

Reprocess target compounds in SIM reduces RL by factor 10.

Enviro-forensics Chlorine Stable Isotope Analysis

11

Air Phase Toxicity Petroleum Hydrocarbon

Table IX A-3: Analyte List for WSC-CAM-IX A

(MassDEP APH)

Analyte CASN

1,3-Butadiene 106990

Methyl-tert-butyl ether 1634044

Benzene 71432

Toluene 108883

Ethylbenzene 100414

m & p-Xylene1 1330207

o-Xylene1 95476

Naphthalene 91203

C5-C8 Aliphatic

Hydrocarbons

NA

C9-C12 Aliphatic Hydrocarbons

NA

C9-C10 Aromatic

Hydrocarbons

NA

NA – Not Applicable

1May be reported and evaluated as mixed isomers.12

Method finalized (December 2009)

Laboratory will not subtract-out “non- petroleum hydrocarbons” unless requested

http://www.mass.gov/dep/cleanup/la

ws/camqa.htm#APH2

Flow Controller Design Details

• Passive sampling technique

• Use for composite or Time Weighted Average (TWA) sampling (0.5 to 24 hr period)

Ambient Air F.C.

Vacuum

gauge

Mechanical

diaphragm

Diaphragm

adjustment

Critical orifice

w/ 2 µm filter

Outlet (to canister)

13

TO-17 TD Tubes as Passive Monitors

• Diffusive Uptake Rate: dependent

on tube dimensions and diffusion

coefficient of analytes

• Only small surface area of a single

adsorbent exposed

• Strong Adsorbent: Only light

analytes released during analysis

• Weak Adsorbent: Heavier analytes

retained during analytes.

• Passive Monitoring: Short list of

Analytes

14

15

EPA Method TO 17

Sample

Stream

ADSORB

DESORB

Strongest

Adsorbent

Weaker

Adsorbent

Strong

Adsorbent

Carrier for

Desorption

Thermal Desorption (TD) Tubes

TO-17 Reporting

16

Reporting in ug/M3 based on volume of sample collected

1 L sample for Analyte with 1ng/tube RL = 1ug/M3

EPA Method 325

17

http://www.markes.com/Products/EPA-Method-325-Product-Group.aspx

Passive Monitors

Cautions• Environmental factors, temperature, wind speed/ air movement

Humidity & particulates

• Media has a Finite Capacity & problematic for certain chemicals

• Different protocols: Solvent Extraction or Thermal desorption (TO-17)

• Regulatory acceptance

Current uses• Limited Analytes for on going monitoring

• Investigative Semi-quantitative tool: soil gas surveys

• Mitigation/longer term stewardship. States incl: NC, NY

EPA Position Paper on use of Passive Monitors

http://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100MK4Z.pdf

18

Variability Document Field Activities

Systematic & Exhaustive Field Documentation is Critical

1. Sample identification

2. Sample location, date and time of sample collection

3. Sampling depth (soil gas or sub-slab)

4. Sampling height (indoor or outdoor)

5. Outdoor, Atmospheric conditions, wind direction, sources in vicinity

6. Identity of samplers , Sampling methods and devices, purge volumes and

devices used

7. Vacuum (pressure) of Summa canister before and after sample collection

8. PID readings must be recorded on the chain-of-custody form and sampling

forms

9. Apparent moisture content (dry, moist, saturated, etc.) of the sampling zone

10. Type of soil present in the sampling zone (e.g., clay, sand, gravel, etc.)

11. Chain-of-custody records to track samples from sampling point to analysis

12. Record SUMMA Canister & Flow controller ID’s on Chain of Custody

13. Leak Check protocol and compound used …Helium?

19

Soil Gas & Sub-Slab Sampling

20

Significant impact on Data Quality can occur during sampling. Leaks

• “Shut-in Check” confirms integrity of surface assembly

• Leak Check demonstrates surface seal at the annular seal

of subsurface probes

– Helium Leak check, Helium is preferred

– Water Dam

NJDEP VITG 2018

Canister Set up

21

22

Air / Vapor Sample Duplicates

Indoor Air /Ambient Duplicates

What QA/QC: Field Duplicate Dilemma

23

Considerations for Data Usability Review

Evaluation of Representativeness and Data Usability

Some considerations:

• Use of Field/Screening Data Sampling Rationale and

Samples collected

• Temporal Distribution of Samples

• Completeness, Inconsistency and Uncertainty

• Information Considered Unrepresentative

24

Summary

Steps to Reduce Uncertainty and to Improve Confidence in Decision

Making

• Project Planning / Conceptual Site Model / Multiple Lines of Evidence

• Quality Assurance Project Plan / Analyte List / QAQC/ RLs / Reg

Criteria

• Field Sampler Skill Level - Who actually collects the samples

• Data Assessment, Evaluation, Usability, Interpretation, Applicability

• Validation of Laboratory Data - Skill Level of assigned staff

25

Contact:

Will Elcoate

National Air Product Manager

Tel: 508.330.3753

welcoate@alphalab.com

www.alphalab.com

Questions