of TPH in Petroleum Vapors Implications for Potential Vapor Intrusion Hazards Roger Brewer amp Lynn Bailey Hazard Evaluation and Emergency Response Hawaii Department of Health April 2012 ID: 915135
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Slide1
Field Investigation of the Chemistry and Toxicity
of TPH in Petroleum Vapors: Implications for Potential Vapor Intrusion Hazards
Roger Brewer & Lynn BaileyHazard Evaluation and Emergency ResponseHawai‘i Department of Health April 2012
1
Slide2There 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
Slide3Reference:
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/3
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.
Slide4Acknowledgements
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.4
Slide5HDOH 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/m
3
(based on this study).
5
Slide6Vapor Intrusion
Indoor Air
Action Level
vapor diluted
Slab or crawl space
contaminated soil or groundwater
diffusion to slab base
advective flow into building
Subslab Soil Gas
Action Level
Soil Gas
AL
res
= 1,000 x Indoor Air AL
Soil Gas AL
C/I
= 2,000 x Indoor Air AL
6
Slide7Do We Really Need to Worry About TPH?
How can something that smells so bad or
can catch on fire pass a “risk assessment”?7
Slide8Key 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? 8
Slide9Gasolines
Diesel Fuels
Fuel Oils
Fuels and Carbon Ranges
C2
C4
C6
C8
C12
C16
C20
C24
C28
C32
C36
69'C
126'C
216'C
343'C
402'C
449'C
C0
BTEX
PAHs
Methane
V
olatile
/Semi-Volatile
9
Slide10Toxicity of Total Petroleum Hydrocarbons
TPH Working Group (mid/late 1990s)
Subsequent Guidance Massachusetts DEP (1997+) Washington DOE (2006) California EPA (DTSC 2009) USEPA (2009)
10
Slide11Massachusetts DEP TPH Carbon Ranges
C5-8
C9-12
C11-22
C19-36
C13-18
Potential Vapor Phase
C2
C4
C6
C8
C12
C16
C20
C24
C28
C32
C36
C0
C9 -10
Aliphatics
Aromatics
Gasolines
Diesel Fuels
Fuel Oils
TPH = Sum of Aromatics + Aliphatics (excluding BTEXN, etc.)
11
Slide12C2
C4
C6
C8
C12
C16
C20
C24
C28
C32
C36
C0
Vapor-Phase Carbon Ranges
C5-8
C9-18
C9-16
Less Toxic
Gasolines
Diesel Fuels
Fuel Oils
More Toxic
TPH = Sum of Aromatics + Aliphatics (excluding BTEXN, etc.)
12
Aliphatics
Aromatics
Slide13Carbon Ranges - Vapor Sample Collection
Volatile
Petroleum Hydrocarbons (VPH):C5-C8 AliphaticsC9-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
13
Slide14TPH Carbon Range Action Levels
Carbon Range
RfC
(ug/m
3
)
Residential
Indoor Air (ug/m
3
)
Residential
Soil Gas (ug/m
3
)
C5-8 aliphatics
600630630,000C9-18 aliphatics
100
100
100,000
C9-16 aromatics
100
100
100,000
USEPA 2009 Reference Concentrations
Target Hazard Quotient = 1.0
Assumes indoor
air:subslab
soil gas Attenuation Factor of 0.001
Odor Threshold (ug/m
3
) approximately 1,000 ug/m
3
Use same as action levels for BTEXN and other individual VOCs
14
Slide15TPH Mixtures: Weighted Toxicity & Action Levels
Weighted
TPH RfC
= 216
ug/m
3
TPH Indoor
Air
res
= 250 ug/m
3
TPH Soil
Gas
res
= 250,000 ug/m
3Weighted TPH RfC (ug/m3) =C9-C18 AliphaticsC5-C8 AliphaticsC9-C16 Aromatics15
Slide16Critical
TPH:Target Compound Ratios
Point where relative proportion of “less toxic” vapor-phase TPH will overwhelm “more toxic” individual compoundsCritical TPH Ratio =
Least Stringent TPH Action Level
Most Stringent Target Compound Action Level
Critical
TPH:Benzene
Ratio =
630 ug/m
3
(C5-C8 aliphatics)
0.31 ug/m
3
(10
-6
cancer risk)Critical TPH:Benzene Ratio = 2,032TPH will always drive vapor intrusion risk if the TPH:Benzene ratio exceeds 2,032:1Useful as initial screening tool to evaluate potential vapor intrusion risk drivers16
Slide17TPH:Benzene
Soil Gas Ratio
Risk Driver
>2,032
TPH will
always
drive
vapor intrusion
risk
(TPH
HQ >1.0 when benzene ECR <10
-6
)
3 to 2,032
TPH could drive vapor intrusion hazards(depends on carbon range makeup and target benzene risk)<3Benzene will always drive vapor intrusion risk.(TPH HQ <1.0 when benzene ECR <10-4)
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.
17
Slide18TPH Will
Always Drive VI Risk if…
VOCIndoor Air Action Level (ug/m
3
)
Critical TPH Ratio
Naphthalene
0.072
8,750
1-Methylnaphthalene
0.29
2,172
Benzene
0.31
2,032
Ethylbenzene
0.97
649
Xylenes
21
30
Toluene
1,000
0.6
Based on least conservative TPH action level (630 ug/m
3
) 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.
18
Slide19Off To The Field!
Key sites for collection of soil gas samples identified;Two phases of sampling:
Phase I: Summas, TO-15 & MA-APHPhase II: Summas+Sorbent Tubes, TO-3, TO-15, TO-17 & MA-APH19
Slide20TO-15
TO-17
Sorbent Tube Range
Summas
or Sorbent Tubes for Soil Gas?
(
Summas
will miss heavier VOCs)
C2
C4
C6
C8
C12
C16
C20
C24
C28
C32
C36
C0
Summa Range
(Hayes 2007)
Larger volume
Familiarity
Limited to C12
Summas
Sorbent Tubes
Up to C24+
Small volume (50ml)
Saturation limitation
Less familiar
20
Slide21Key Study Sites
Site
DSite
A
Site
B
Site E
Site
C
21
Slide22Sample Collection
Summa Canisters
(1liter summas)Sorbent Tubes(60 ml syringes)
22
Max Draw = 50ml
Two Tubes to
Evaluate Breakthrough
Slide23Results of Field Data
Following summaries based on Summa canister dataSorbent tube data very similar to Summa data
Minimal VOCs greater than C12 in soil gasNaphthalene was usually ND and not a significant risk driver in comparison to TPH (or benzene)TEX likewise not significant risk drivers23
Slide24TPH Dominates BTEXN in Vapors
(BTEXN component decreases in aged releases?)
Site/Fuel TypeAverage Soil Gas Composition(TO-15 Data)
TPH
*BTEXN
TPH:Benzene
Gasoline (Fresh Vapors)
91.6%
8.4%
170
Diesel (Fresh Vapors)
93.7%
6.3%
206
JP-8 (Fresh Vapors)
96.4%
3.6%
301
Site A
(JP-4/AVGAS
?)
99.6%
0.4%
1,513
Site B
(mixed
fuels)
99.5%
0.5%
4,174
Site C
(JP-8
+/- JP-4)
99.7%
0.3%
18,710
Site D
(MOGAS/JP-4/AVGAS)
98.3%
1.7%
9,135
Site E
(
diesel)
99.9%
0.1%
18,611
*Exhaust samples 30-40% BTEXN
24
Slide25TO-15 Gas Chromatograph
Fresh Gasoline Vapors
C5-C8
Benzene
C5
C9
C9-12
Naphthalene
C13
25
Slide26Weighted RfC= 565 ug/m
3Indoor
Airres = 590 ug/m3Soil Gasres = 590,000 ug/m3
TPH:Benzene
= 170
Carbon Range Chemistry and Weighted TPH Toxicity
Fresh Gasoline Vapors
Based on TO-15 Summa Data
C9-C12 Aliphatics
C5-C8 Aliphatics
C9-C10 Aromatics
Slide27Who’s Driving…?
TPH vs Benzene as VI Risk DriverCalculate equivalent TPH concentration for sample/site at target benzene action level based on
TPH:Benzene ratioDivide by weighted site-specific TPH action levelGasoline 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/m
3
Weighted TPH Action Level = 590 ug/m
3
TPH noncancer HQ = 53/590 = 0.1
Benzene
drives vapor intrusion risk (TPH HQ <1.0 when benzene risk = 10
-6)27
Slide28Benzene
TPH Hazard Quotient
TPH vs Benzene Vapor Intrusion RiskFresh Gasoline Vapors
Benzene Cancer Risk
10
-6
0
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
)
TPH
HQ=0.1Based on TO-15 Summa Data28
Slide29TO-15 Gas Chromatograph
Fresh Diesel Vapors
C5-C8
C9-12
Benzene
Naphthalene
C5
C9
C13
29
Slide30Weighted RfC= 216
ug/m
3
Indoor
Air
res
= 250 ug/m
3
Soil
Gas
res
= 250,000 ug/m
3
TPH:Benzene
= 206
Carbon Range Chemistry and Weighted TPH ToxicityFresh Diesel VaporsBased on TO-15 Summa DataC9-C12 AliphaticsC5-C8 AliphaticsC9-C10 Aromatics30
Slide31Based on TO-15 Summa Data
31
TPHBenzeneHQ=0.3
TPH vs Benzene Vapor Intrusion Risk
Fresh
Diesel Vapors
TPH Hazard Quotient
Benzene Cancer Risk
10
-6
0
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)
Slide32Gas Chromatograph
Fresh JP-8 Vapors
C5-C8Benzene
C5
C9-12
Naphthalene
C13
C9
32
Slide33Weighted RfC= 225
ug/m
3Indoor Air
res
= 230 ug/m
3
Soil
Gas
res
= 230,000 ug/m
3
TPH:Benzene
= 301
Carbon Range Chemistry and Weighted TPH Toxicity
Fresh JP-8 Vapors
Based on TO-15 Summa DataC9-C12 AliphaticsC5-C8 AliphaticsC9-C10 Aromatics33
Slide34TPH
Benzene
HQ=0.4
TPH vs Benzene Vapor Intrusion Risk
Fresh JP-8 Vapors
TPH Hazard Quotient
Benzene Cancer Risk
10
-6
0
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
)Based on TO-15 Summa Data34
Slide35Gas Chromatograph
Site A (AVGAS)
C5-C8
Benzene
C5
C9
C9-12
Naphthalene
C13
35
Slide36Weighted RfC= 510
ug/m
3Indoor
Air
res
= 530 ug/m
3
Soil
Gas
res
= 530,000 ug/m
3
TPH:Benzene
= 1,513!
(reduced benzene in soil gas)
Carbon Range Chemistry and Weighted TPH ToxicitySite A (AVGAS)Average TPH in Soil Gas71,000,000 ug/m3Based on TO-15 Summa DataC9-C12 AliphaticsC5-C8 AliphaticsC9-C10 Aromatics36
Slide37TPH
Benzene
HQ=0.9
TPH vs Benzene Vapor Intrusion Risk
Site A (AVGAS
)
TPH Hazard Quotient
Benzene Cancer Risk
10
-6
0
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)Based on TO-15 Summa Data37
Slide38Chemical/
Carbon Range
*Henry’s Constant
Benzene
0.23
Ethylbenzene
0.32
Toluene
0.27
Xylenes
0.29
Naphthalene
0.018
C9-C10 Aromatics
0.33
C11-C22 Aromatics
0.03
C5-C8 Aliphatics
54
C9-C12 Aliphatics
65
C9-C18 Aliphatics
69
C19-C36 Aliphatics
110
Where’s the BTEXN? Partitioning of Compounds in Soil
*Theoretical ratio of vapor-phase mass to dissolved-phase mass at equilibrium. Dissolved-phase dominates if H’ <1.0.
Aromatics Prefer to be in the Water
Aliphatics Prefer to be in the Vapors
38
Slide39Gas Chromatograph
Site B (Mixed Fuels)
C5-C8
Benzene
C5
C9
C9-12
Naphthalene
C13
39
Slide40Weighted RfC= 443
ug/m
3Indoor Air
res
= 460 ug/m
3
Soil
Gas
res
= 460,000 ug/m
3
TPH:Benzene
= 4,174!
(reduced benzene in soil gas)
Carbon Range Chemistry and Weighted TPH Toxicity
Site B (Mixed fuels)Average TPH in Soil Gas44,000,000 ug/m3Based on TO-15 Summa DataC9-C12 AliphaticsC5-C8 AliphaticsC9-C10 Aromatics40
Slide41TPH
Benzene
HQ=2.8
TPH vs Benzene Vapor Intrusion Risk
Site B (
Mixed
Fuels
)
TPH Hazard Quotient
Benzene Cancer Risk
10
-6
0
TPH
always
drives potential vapor intrusion hazards. (TPH noncancer HQ>1 even when benzene risk 10-6)Based on TO-15 Summa Data41
Slide42Gas Chromatograph
Site C (JP-8 +/- J-4)
C5-C8
Benzene
C5
C9
C9-12
Naphthalene
C13
42
Slide43Weighted RfC= 251
ug/m
3Indoor
Air
res
= 260 ug/m
3
Soil
Gas
res
= 260,000 ug/m
3
TPH:Benzene
= 18,710!!
(minimal benzene in soil gas)
Carbon Range Chemistry and Weighted TPH Site C (JP-8 +/- JP-4)Average TPH in Soil Gas17,000,000 ug/m3Based on TO-15 Summa DataC9-C12 AliphaticsC5-C8 AliphaticsC9-C10 Aromatics43
Slide44TPH
Benzene
HQ=22
TPH vs Benzene Vapor Intrusion Risk
Site C
(JP-8
+/- J-4)
TPH Hazard Quotient
Benzene Cancer Risk
10
-6
0
TPH
always
drives potential vapor intrusion hazards.
(TPH noncancer HQ>1 even when benzene risk 10-6)Based on TO-15 Summa Data44
Slide45TO-15 Gas Chromatograph
Site D (JP-4)
C5-C8
Benzene
C5
C9
C9-12
Naphthalene
C13
45
Slide46Weighted RfC= 211
ug/m
3Indoor Air
res
= 220 ug/m
3
Soil
Gas
res
= 220,000 ug/m
3
TPH:Benzene
= 9,135!
(minimal benzene in soil gas)
Carbon Range Chemistry and Weighted TPH
Site D (JP-4)Average TPH in Soil Gas630,000 ug/m3Based on TO-15 Summa DataC9-C12 AliphaticsC5-C8 AliphaticsC9-C10 Aromatics46
Slide47TPH
Benzene
HQ=13
TPH vs Benzene Vapor Intrusion Risk
Site D (JP-4
)
TPH Hazard Quotient
Benzene Cancer Risk
10
-6
0
TPH
always
drives potential vapor intrusion hazards.
(TPH noncancer HQ>1 even when benzene risk 10
-6)Based on TO-15 Summa Data47
Slide48Gas Chromatograph
Site E (Diesel)
C5-C8
Benzene
C5
C9
C9-12
Naphthalene
C13
48
Slide49Weighted RfC= 127
ug/m
3Indoor
Air
res
= 130 ug/m
3
Soil
Gas
res
= 130,000 ug/m
3
TPH:Benzene
= 18,600!!
(minimal benzene in soil gas)
Carbon Range Chemistry and Weighted TPH Site E (Diesel)Average TPH in Soil Gas2,900,000 ug/m3*Reference site for default TPH RfC in Fall 2011 TPH soil gas action levels.Based on TO-15 Summa DataC9-C12 AliphaticsC5-C8 AliphaticsC9-C10 Aromatics49
Slide50TPH
Benzene
HQ=44
TPH vs Benzene Vapor Intrusion Risk
Site E
(Diesel
)
TPH Hazard Quotient
Benzene Cancer Risk
10
-6
0
TPH
always
drives potential vapor intrusion hazards.
(TPH noncancer HQ>1 even when benzene risk 10-6)Based on TO-15 Summa Data50
Slide51TPH vs Benzene as Vapor Intrusion Risk
Site/Fuel Type
Vapor Intrusion Risk Driver
TPH
Drives Risk
*Benzene
Drives Risk
Gasoline (Fresh Vapors)
X
Diesel (Fresh Vapors)
X
JP-8 (Fresh Vapors)
X
Site
A
(JP-4/AVGAS?)
X
X
Site
B
(mixed fuels)
X
Site
C
(JP-8 +/- JP-4)
X
Site
D
(MOGAS/JP-4/AVGAS)
X
Site E
(diesel)
X
*Assuming a target, 10
-6
cancer risk is used for benzene.
51
Slide52Other Sites TPH vs BTEXN
Site/Fuel Type
TPH:BenzeneIn Soil Gas
HAFB SS156-E (gasolines)
244 to 1,296
ConocoPhillips (mixed)
97 to 5,400
Lipoa
Place (mixed)
82
to >6,400
Challenger Loop (JP-4, JP-8)
2,800 to 5,100
Aloha Petroleum
(gasolines)
366 to 13,100
HAFB SS156-J (mixed)
560 to 165,000
HAFB CG110 (diesels)
1,600,000
TPH:Benzene
ratio highly variable
Best to always test for TPH
52
Slide53Back 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.53
Slide54Key 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/m
3
(presence
of C9-C12
aliphatics)
TPH Indoor air action levels similar to TPH RfC
54
Slide55Key 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.
55
Slide56Key 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).56
Slide57Already 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…
57
Slide58RfCs
AFs
Biodegradation
TPH
Carbon
Ranges
Don’t Panic!
BTEXN
Subslab
Vapor
Intrusion
Next Step: Pre-Screening Sites for
Potential Vapor Intrusion Concerns
58
Slide59Avoid 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)?
Risk Pyramid of Investigated Sites
Site Screening Bar
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)
59
Slide60Avoid Setting The Site Screening Bar Too
High
Risk Pyramid of Investigated Sites
Site Screening Bar
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)
60
Slide61Screening 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 minimis volumes 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.
61