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Field Investigation of the Chemistry and Toxicity of TPH in Petroleum Vapors: Implications for Potential Vapor Intrusion Hazards. Roger Brewer & Lynn Bailey Hazard Evaluation and Emergency Response Hawai‘i Department of Health April 2012. There are three methods to gain knowledge:

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Field investigation of the chemistry and toxicity of tph in petroleum vapors

Field Investigation of the Chemistry and Toxicity

of TPH in Petroleum Vapors:

Implications for Potential Vapor Intrusion Hazards

Roger Brewer & Lynn Bailey

Hazard Evaluation and Emergency Response

Hawai‘i Department of Health

April 2012


Field investigation of the chemistry and toxicity of tph in petroleum vapors

There are three methods to gain knowledge:

The first, reflection, is the noblest;

The second, imitation, is the easiest;

And the third, experience, is the bitterest.

Confucius


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Reference:

Field Investigation of the Chemistry and Toxicity of TPH in Petroleum Vapors, Implications for Potential Vapor Intrusion Hazards: Hawai’i Department of Health, Hazard Evaluation and Emergency Response, http://www.hawaiidoh.org/

Note: Significant vapor intrusion problems have not been identified for existing buildings at any of the study sites included in this presentation. The site data are presented for example only.


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Acknowledgements

  • Field study funded under a grant from USEPA Region IX;

  • Hickam AFB/NAVFAC Hawai’i past work and field assistance

  • Field work carried out by HDOH HEER & UST staff with assistance by several local consultants;

  • Numerous consultations with regulators and consultants on the mainland.


Field investigation of the chemistry and toxicity of tph in petroleum vapors

HDOH Petroleum Vapor Intrusion Guidance

  • HEER EHE guidance (2005; last updated Fall, 2011)

  • HEER Technical Guidance Manual (Section 9);

  • Test for TPH plus BTEXN and methane in soil gas;

  • TPH soil gas action levels:

    • 2005: Residential = 26,000 ug/m3 (based on limited, published information);

    • 2011: Residential = 130,000+ ug/m3 (based on this study).


Vapor intrusion

Vapor Intrusion

vapor diluted

advective flow into building

Indoor Air

Action Level

Slab or crawl space

Subslab Soil Gas

Action Level

diffusion to slab base

Soil Gas ALres = 1,000 x Indoor Air AL

Soil Gas ALC/I = 2,000 x Indoor Air AL

contaminated soil or groundwater


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Do We Really Need to Worry About TPH?

How can something that smells so bad or

can catch on fire pass a “risk assessment”?


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Key Questions…

1.Are BTEXN and especially benzene in soil gas adequate to screen for potential vapor intrusion hazards at petroleum-contaminated sites?

2. Could TPH still pose a vapor intrusion risk even though BTEXN meet acceptable risks?

a. What is the toxicity of TPH in petroleum vapors?

b. What is carbon range makeup of vapor-phase TPH?


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Fuels and Carbon Ranges

Gasolines

Diesel Fuels

Fuel Oils

Volatile/Semi-Volatile

69'C

126'C

216'C

343'C

402'C

449'C

C6

C4

C12

C2

C8

C24

C16

C20

C0

C32

C28

C36

Methane

BTEX

PAHs


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Toxicity of Total Petroleum Hydrocarbons

TPH Working Group (mid/late 1990s)

  • Subsequent Guidance

  • Massachusetts DEP (1997+)

  • Washington DOE (2006)

  • California EPA (DTSC 2009)

  • USEPA (2009)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Massachusetts DEP TPH Carbon Ranges

Aromatics

Gasolines

Aliphatics

Diesel Fuels

Fuel Oils

Potential Vapor Phase

C9 -10

C11-22

C5-8

C9-12

C13-18

C19-36

C6

C4

C12

C2

C8

C24

C16

C20

C0

C32

C28

C36

TPH = Sum of Aromatics + Aliphatics (excluding BTEXN, etc.)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Vapor-Phase Carbon Ranges

Aromatics

Gasolines

Aliphatics

Diesel Fuels

Fuel Oils

Less Toxic

More Toxic

C9-16

C6

C4

C12

C2

C8

C24

C16

C20

C32

C28

C36

C5-8

C9-18

C0

TPH = Sum of Aromatics + Aliphatics (excluding BTEXN, etc.)


Carbon ranges vapor sample collection

Carbon Ranges - Vapor Sample Collection

  • Volatile Petroleum Hydrocarbons (VPH):

  • C5-C8 Aliphatics

  • C9-C12 Aliphatics

  • C9-C10 Aromatics

  • Extractable Petroleum Hydrocarbons (EPH):

  • C13-C16 Aliphatics

  • C11-C16 Aromatics

  • VPH Compounds: Summa canisters OK

  • EPH Compounds: Sorbent tubes required


Tph carbon range action levels

TPH Carbon Range Action Levels

  • USEPA 2009 Reference Concentrations

  • Target Hazard Quotient = 1.0

  • Assumes indoor air:subslab soil gas Attenuation Factor of 0.001

  • Odor Threshold (ug/m3) approximately 1,000 ug/m3

  • Use same as action levels for BTEXN and other individual VOCs


Tph mixtures weighted toxicity action levels

TPH Mixtures: Weighted Toxicity & Action Levels

Weighted TPH RfC= 216 ug/m3

TPH Indoor Airres = 250 ug/m3

TPH Soil Gasres = 250,000 ug/m3

C5-C8 Aliphatics

C9-C18 Aliphatics

C9-C16 Aromatics

Weighted TPH RfC (ug/m3) =


Critical tph target compound ratios

Critical TPH:Target Compound Ratios

  • Point where relative proportion of “less toxic” vapor-phase TPH will overwhelm “more toxic” individual compounds

Least Stringent TPH Action Level

Most Stringent Target Compound Action Level

Critical TPH Ratio =

630 ug/m3 (C5-C8 aliphatics)

0.31 ug/m3 (10-6 cancer risk)

Critical TPH:Benzene Ratio =

Critical TPH:Benzene Ratio =

2,032

  • TPH will always drive vapor intrusion risk if the TPH:Benzene ratio exceeds 2,032:1

  • Useful as initial screening tool to evaluate potential vapor intrusion risk drivers


Tph vs benzene in vapor intrusion risk

TPH vs Benzene in Vapor Intrusion Risk

Notes

High: Ratio of least stringent TPH action level to most stringent benzene action level.

Low: Ratio of least stringent TPH action level to most stringent benzene action level.


Tph will always drive vi risk if

TPH Will Always Drive VI Risk if…

  • Based on least conservative TPH action level (630 ug/m3) and most conservative VOC action level (e.g., 10-6 cancer risk and HQ 1.0).

  • TPH could drive vapor intrusion risk below these ratios depending on carbon range makeup and target risk applied to the individual VOC.


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Off To The Field!

  • Key sites for collection of soil gas samples identified;

  • Two phases of sampling:

    • Phase I: Summas, TO-15 & MA-APH

    • Phase II: Summas+Sorbent Tubes, TO-3, TO-15, TO-17 & MA-APH


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Summas or Sorbent Tubes for Soil Gas?

(Summas will miss heavier VOCs)

(Hayes 2007)

Summas

Sorbent Tubes

  • Up to C24+

  • Small volume (50ml)

  • Saturation limitation

  • Less familiar

  • Larger volume

  • Familiarity

  • Limited to C12

TO-15

TO-17

C6

C4

C12

C2

C8

C24

C16

C20

C32

C28

C36

C0

Summa Range

Sorbent Tube Range


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Key Study Sites

Site A

Site D

Site C

Site E

Site B


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Sample Collection

Sorbent Tubes

(60 ml syringes)

Summa Canisters

(1liter summas)

Max Draw = 50ml

Two Tubes to

Evaluate Breakthrough


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Results of Field Data

  • Following summaries based on Summa canister data

  • Sorbent tube data very similar to Summa data

  • Minimal VOCs greater than C12 in soil gas

  • Naphthalene was usually ND and not a significant risk driver in comparison to TPH (or benzene)

  • TEX likewise not significant risk drivers


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH Dominates BTEXN in Vapors

(BTEXN component decreases in aged releases?)

*Exhaust samples 30-40% BTEXN


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TO-15 Gas Chromatograph

Fresh Gasoline Vapors

C5-C8

C9-12

C13

C5

C9

Benzene

Naphthalene


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Carbon Range Chemistry and Weighted TPH Toxicity

Fresh Gasoline Vapors

Weighted RfC= 565 ug/m3

Indoor Airres = 590 ug/m3

Soil Gasres = 590,000 ug/m3

TPH:Benzene = 170

C5-C8 Aliphatics

C9-C12 Aliphatics

C9-C10 Aromatics

Based on TO-15 Summa Data


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Who’s Driving…?

TPH vs Benzene as VI Risk Driver

  • Calculate equivalent TPH concentration for sample/site at target benzene action level based on TPH:Benzene ratio

  • Divide by weighted site-specific TPH action level

  • Gasoline Vapor Example (using indoor air action levels):

  • Target Benzene Action Level = 0.31 ug/m3 (10-6 risk)

  • TPH:Benzene = 170:1

  • Equivalent TPH = 53 ug/m3

  • Weighted TPH Action Level = 590 ug/m3

  • TPH noncancer HQ = 53/590 = 0.1

  • Benzene drives vapor intrusion risk (TPH HQ <1.0 when benzene risk = 10-6)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH vs Benzene Vapor Intrusion Risk

Fresh Gasoline Vapors

Benzene Cancer Risk

TPH Hazard Quotient

10-6

TPH

HQ=0.1

Benzene

0

Based on TO-15 Summa Data

Benzene adequate to evaluate vapor intrusion

provided that a target 10-6 cancer risk is used.

(TPH noncancer HQ still <1 when benzene risk 10-6)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TO-15 Gas Chromatograph

Fresh Diesel Vapors

C5-C8

C9-12

C5

C9

C13

Benzene

Naphthalene


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Weighted RfC= 216 ug/m3

Indoor Airres = 250 ug/m3

Soil Gasres = 250,000 ug/m3

TPH:Benzene = 206

Carbon Range Chemistry and Weighted TPH Toxicity

Fresh Diesel Vapors

C5-C8 Aliphatics

C9-C12 Aliphatics

C9-C10 Aromatics

Based on TO-15 Summa Data


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH vs Benzene Vapor Intrusion Risk

Fresh Diesel Vapors

Benzene Cancer Risk

TPH Hazard Quotient

10-6

Benzene

TPH

HQ=0.3

0

Based on TO-15 Summa Data

Benzene adequate to evaluate vapor intrusion

provided that a target 10-6 cancer risk is used.

(TPH noncancer HQ still <1 when benzene risk 10-6)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Gas Chromatograph

Fresh JP-8 Vapors

C5-C8

C9-12

C13

C5

C9

Benzene

Naphthalene


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Carbon Range Chemistry and Weighted TPH Toxicity

Fresh JP-8 Vapors

Weighted RfC= 225 ug/m3

Indoor Airres = 230 ug/m3

Soil Gasres = 230,000 ug/m3

TPH:Benzene = 301

C5-C8 Aliphatics

C9-C12 Aliphatics

C9-C10 Aromatics

Based on TO-15 Summa Data


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH vs Benzene Vapor Intrusion Risk

Fresh JP-8 Vapors

Benzene Cancer Risk

TPH Hazard Quotient

10-6

TPH

Benzene

HQ=0.4

0

Based on TO-15 Summa Data

Benzene adequate to evaluate vapor intrusion hazards provided that a target 10-6 cancer risk is used.

(TPH noncancer HQ<1 when benzene risk 10-6)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Gas Chromatograph

Site A (AVGAS)

C5-C8

C9-12

C13

C5

C9

Benzene

Naphthalene


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Carbon Range Chemistry and Weighted TPH Toxicity

Site A (AVGAS)

Weighted RfC= 510 ug/m3

Indoor Airres = 530 ug/m3

Soil Gasres = 530,000 ug/m3

TPH:Benzene = 1,513!

(reduced benzene in soil gas)

C5-C8 Aliphatics

C9-C12 Aliphatics

C9-C10 Aromatics

Average TPH in Soil Gas

71,000,000 ug/m3

Based on TO-15 Summa Data


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH vs Benzene Vapor Intrusion Risk

Site A (AVGAS)

Benzene Cancer Risk

TPH Hazard Quotient

10-6

TPH

Benzene

HQ=0.9

0

Based on TO-15 Summa Data

Benzene adequate to evaluate vapor intrusion hazards provided that a target 10-6 cancer risk is used.

(TPH noncancer HQ<1 when benzene risk 10-6)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Where’s the BTEXN? Partitioning of Compounds in Soil

Aromatics Prefer to be in the Water

Aliphatics Prefer to be in the Vapors

*Theoretical ratio of vapor-phase mass to dissolved-phase mass at equilibrium. Dissolved-phase dominates if H’ <1.0.


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Gas Chromatograph

Site B (Mixed Fuels)

C5-C8

C9-12

C13

C5

C9

Benzene

Naphthalene


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Carbon Range Chemistry and Weighted TPH Toxicity Site B (Mixed fuels)

Weighted RfC= 443 ug/m3

Indoor Airres = 460 ug/m3

Soil Gasres = 460,000 ug/m3

TPH:Benzene = 4,174!

(reduced benzene in soil gas)

C5-C8 Aliphatics

C9-C12 Aliphatics

C9-C10 Aromatics

Average TPH in Soil Gas

44,000,000 ug/m3

Based on TO-15 Summa Data


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH vs Benzene Vapor Intrusion Risk

Site B (Mixed Fuels)

Benzene Cancer Risk

TPH Hazard Quotient

TPH

HQ=2.8

10-6

Benzene

0

Based on TO-15 Summa Data

TPH always drives potential vapor intrusion hazards.

(TPH noncancer HQ>1 even when benzene risk 10-6)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Gas Chromatograph

Site C (JP-8 +/- J-4)

C5-C8

C9-12

C5

C9

C13

Benzene

Naphthalene


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Carbon Range Chemistry and Weighted TPH

Site C (JP-8 +/- JP-4)

Weighted RfC= 251 ug/m3

Indoor Airres = 260 ug/m3

Soil Gasres = 260,000 ug/m3

TPH:Benzene = 18,710!!

(minimal benzene in soil gas)

C5-C8 Aliphatics

C9-C12 Aliphatics

C9-C10 Aromatics

Average TPH in Soil Gas

17,000,000 ug/m3

Based on TO-15 Summa Data


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH vs Benzene Vapor Intrusion Risk

Site C (JP-8 +/- J-4)

Benzene Cancer Risk

TPH Hazard Quotient

TPH

HQ=22

10-6

Benzene

0

Based on TO-15 Summa Data

TPH always drives potential vapor intrusion hazards.

(TPH noncancer HQ>1 even when benzene risk 10-6)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TO-15 Gas Chromatograph

Site D (JP-4)

C5-C8

C9-12

C5

C9

C13

Benzene

Naphthalene


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Carbon Range Chemistry and Weighted TPH

Site D (JP-4)

Weighted RfC= 211 ug/m3

Indoor Airres = 220 ug/m3

Soil Gasres = 220,000 ug/m3

TPH:Benzene = 9,135!

(minimal benzene in soil gas)

C5-C8 Aliphatics

C9-C12 Aliphatics

C9-C10 Aromatics

Average TPH in Soil Gas

630,000 ug/m3

Based on TO-15 Summa Data


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH vs Benzene Vapor Intrusion Risk

Site D (JP-4)

Benzene Cancer Risk

TPH Hazard Quotient

TPH

HQ=13

10-6

Benzene

0

Based on TO-15 Summa Data

TPH always drives potential vapor intrusion hazards.

(TPH noncancer HQ>1 even when benzene risk 10-6)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Gas Chromatograph

Site E (Diesel)

C5-C8

C9-12

C5

C9

C13

Benzene

Naphthalene


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Carbon Range Chemistry and Weighted TPH

Site E (Diesel)

*Reference site for default TPH RfC in Fall 2011 TPH soil gas action levels.

Weighted RfC= 127 ug/m3

Indoor Airres = 130 ug/m3

Soil Gasres = 130,000 ug/m3

TPH:Benzene = 18,600!!

(minimal benzene in soil gas)

C5-C8 Aliphatics

C9-C12 Aliphatics

C9-C10 Aromatics

Average TPH in Soil Gas

2,900,000 ug/m3

Based on TO-15 Summa Data


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH vs Benzene Vapor Intrusion Risk

Site E (Diesel)

Benzene Cancer Risk

TPH Hazard Quotient

TPH

HQ=44

10-6

Benzene

0

Based on TO-15 Summa Data

TPH always drives potential vapor intrusion hazards.

(TPH noncancer HQ>1 even when benzene risk 10-6)


Field investigation of the chemistry and toxicity of tph in petroleum vapors

TPH vs Benzene as Vapor Intrusion Risk

*Assuming a target, 10-6 cancer risk is used for benzene.


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Other Sites TPH vs BTEXN

  • TPH:Benzene ratio highly variable

  • Best to always test for TPH


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Back to the Key Questions…

  • Q: What is TPH in petroleum vapors made of?

  • Answers:

  • Mostly C5-C8 aliphatics, with an increased proportion of C9+ aliphatics in middle distillate (diesel, etc.) vapors.

  • Aromatics, including BTEXN, make up a very minor component of vapors, especially at aged release sites.


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Key Questions…

  • Q:What is the toxicity (RfC) of TPH in petroleum vapors?

  • Answer:

  • Inhalation Reference Concentration for TPH will range from 100 ug/m3 and 600 ug/m3 (based on USEPA 2009 guidance).

  • Vapors from gasolines will be closer to 600 ug/m3. (dominance of C5-C8 aliphatics)

  • Vapors from middle distillates will be closer to 100 ug/m3 (presence of C9-C12 aliphatics)

  • TPH Indoor air action levels similar to TPH RfC


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Key Questions…

  • Q:Are BTEXN and especially benzene in soil gas adequate to screen for potential vapor intrusion risks?

  • Answers (more studies needed):

  • Yes – But only for gasoline-contaminated sites and only if a conservative target risk is used (e.g., 10-6 );

  • Aromatics can be preferentially removed from vapors via partitioning into moisture and degradation (but aliphatics will also be degraded);

  • Reliance on benzene only can miss significant vapor intrusion hazards at diesel/middle distillate sites;

  • TX not present in significant enough amounts to drive vapor intrusion risks at the study sites (ethylbenzene?);

  • Naphthalene not detected in most soil gas samples and not a reliable indicator of vapor intrusion risk.


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Key Questions…

  • Q: Can TPH still pose a vapor intrusion risk even though BTEXN meet acceptable risks?

  • Answers:

  • Yes - TPH drives vapor intrusion risk over BTEXN at four of the five sites tested;

  • TPH data especially important at sites with middle distillates (but vapor emission rates will be lower compared to gasolines);

  • TPH alone would have been adequate to screen all of the study sites for potential vapor intrusion hazards (i.e., take care of the TPH and you will take care of the benzene).


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Already Here & Coming Soon

  • Study data used to update HEER TPH soil gas action levels (based on Fishing Village data);

  • Draft report to be posted in March;

  • Final report to be posted this spring;

  • Methylnaphthalenes? (not significant in this study);

  • Updated TPH Carbon Range guidance and soil gas sample collection guidance to be posted this summer;

  • Comments and ideas always welcome.

Now we know what the source area looks like…


Field investigation of the chemistry and toxicity of tph in petroleum vapors

  • Next Step: Pre-Screening Sites for

  • Potential Vapor Intrusion Concerns

Don’t Panic!

TPH

RfCs

Vapor

Intrusion

BTEXN

Carbon

Ranges

AFs

Subslab

Biodegradation


Field investigation of the chemistry and toxicity of tph in petroleum vapors

  • Avoid Setting The Site Screening Bar Too Low

  • When do we need to look more closely (screening levels)?

  • When is remediation really required (high risk sites)?

High Risk

Remedial Action Ultimately Required

(don’t miss)

Medium Risk

Flagged in Screening but No Action Ultimately Required

(minimize)

Low Risk

Eliminated During Screening, No Further Action Required

(maximize)

Site Screening Bar

Risk Pyramid of Investigated Sites


Field investigation of the chemistry and toxicity of tph in petroleum vapors

  • Avoid Setting The Site Screening Bar Too High

High Risk

Remedial Action Ultimately Required

(don’t miss)

Medium Risk

Flagged in Screening but No Action Ultimately Required

(minimize)

Site Screening Bar

Low Risk

Eliminated During Screening, No Further Action Required

(maximize)

Risk Pyramid of Investigated Sites


Field investigation of the chemistry and toxicity of tph in petroleum vapors

Screening Sites for Further Investigation

  • Let’s Be Rational...:

  • Don’t over compound conservative screening assumptions (e.g., “Tomb Model” for IA:SG attenuation and target 10-6 risk);

  • Biodegradation and attenuation away from source area;

  • Distance from source area;

  • De minimisvolumes of contaminated soil and areas of free product (regardless of concentrations);

  • Other considerations:

  • -Alternative toxicity factors;

  • -Target risks vs typical background;

  • -Tidal pumping &subslab oxygenation

  • -Explosion, odor concerns (including methane);

  • -Focus on subslab data.

  • Avoid testing indoor air (too many indoor & outdoor sources)

  • Balance uncertainty about benefit to human health with certainty about economic impact on property owners.


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