A New Risk-Based Approach to Establish Clean-up Levels

for TPH

David Nakles and Stephen Geiger

ThermoRetec Consulting and Engineering

Sara McMillen and Renae Magaw

Chevron Research and Technology Company

Jill Kerr

Exxon Production Research Company

Robert Sweeney

Unocal

Acknowledgments

Nancy Comstock - Department of Energy: National Petroleum Technology Office

Harley Hopkins - American Petroleum Institute

John Harju - Gas Research Institute

George Deeley/ Ileana Rhodes - Equilon Enterprises, LLC

Michele Emerson - Chevron Research and Technology Company

Acknowledgments (Con’t)

H. Rodger Melton and Maged Hamed - Exxon Production Research Company

Paul Lundegard - Unocal

Deborah Edwards - Exxon Biomedical Sciences, Inc.

Greg Douglas and George Naughton - A.D. Little

Regulation of Environmental Impacts in the United States

Evolving Risk-Based ApproachEvolving Risk-Based Approach

Using state-of-the-art science

Goal: To protect human health and the environment by:

Developing cleanup standards based on:

1. Risk to human health

2. Expected land use

Benefits of the Change

Incorporates new science and methods

Form 4Form 3Form 2Form 1

Benefits of the Change

Provides standardized but flexible approach

Benefits of the Change

Provides more effective site management

Benefits of the Change

Ability to use alternatives to aggressive remedial technologies in all types of settings

Presentation Objectives

Describe risk-based method for determining Describe risk-based method for determining acceptableacceptable concentrations of crude oil in soil concentrations of crude oil in soil

Describe elements of environmental risk

Present methods to assess risk of non-cancer health effects

Demonstrate application of methods to hypothetical E&P site

Identify range of acceptable concentrations for crude oil in soil

Confirm ability to use conventional measurement techniques

Elements of Environmental Risk

Risk is the possibility that something bad Risk is the possibility that something bad mightmight happen happen

Risk Hazard * Exposure * People

Hazard Exposure

People

RiskRisk

Assessing and Managing Risk at Crude Oil Sites

Risk Hazard * Exposure * People

Hazard Exposure

People

RiskRisk

IngestionInhalation

Skin Contact

TPH measurement is not sufficient for hazard evaluation

Need method for understanding the composition of crude oil and its products

Hazard Evaluation of Crude Oil

Estimated that over 100,000 individual compounds exist in crude oil

Toxicity of these compounds varies widely — no one compound can represent mixture

TPH Results Are Method Specific

TPH Methods: Approximate Carbon Ranges

Purgeable/Volatile/Gasoline Range, Modified 8015, Purge and Trap, GC

Diesel Range, Modified 8015, Extraction, GC

418.1, Modified 418.1: Extraction, IR

C2 C4 C6 C8 C10 C12 C14 C16 C18 C20 C22 C24 C26 C28 C30

Gasoline

Diesel Fuel/Middle Distillates

Lube/Motor Oil, Grease

Problems with Using TPH for Assessing Risk

TPH can be measured throughout nature….

…..and not all TPH is the same

Dried Oak Leaves18,000 mg/kg

(1.8%)Crude Oil

618,000 mg/kg(61.8%)

Grass14,000 mg/kg

(1.4%)

Pine Needles16,000 mg/kg

(1.6%)Petroleum Jelly749,000 mg/kg

(74.9%)

Problem with Existing Cleanup Goals for TPH

Different States1

10

100

1,000

10,000

100,000

1,000,000

TP

H C

lea

nu

p L

eve

l (m

g/k

g)

Cleanup Levels

PetroleumJelly

GasolineCrude Oil

Determine TPH composition

Determine risk-based screening levels (RBSLs) of hydrocarbon mixtures in soil

Has been implemented by several states (e.g., Louisiana, Michigan, Alaska,Texas, Ohio)

Solution: Conservatively Estimate Human Health Risk Using Chemical Composition of TPH

New methodology derived from the TPH Criteria Working Group (TPHCWG) — Established in 1995 by the USAF

2 3 4 5

Preferred Option

Risk Assessment Approaches for Petroleum Hydrocarbons

C5 C35

Indicator Approach

Benzene Anthracene

Fraction Approach

C5 5 8 10 12 16 35216

C5-C8 C8-C16 C16-C35

Whole Product Approach

C5 C35

Gasoline Diesel

Determining TPH Composition: Separate TPH into Fractions

Separate based on chemical structure

Aromatics Aliphatics

Toluene (C7H8 or C7) Octane (C8H18)

H|C

H — C

C|C|H

H — C

C — H

C — H

H — — H

H — C — C — C — C — C — C — C — C — H

H|

H|

H|

H|

|H

|H

|H

|H

H|

|H

H|

|H

H|

|H

H|

|H

Determining TPH Composition: Further Separate TPH into 14 Fractions

Further separatebased on

movement in theenvironment

Aromatics Aliphatics

>C6-C7

>C7-C8

>C8-C10

>C10-C12

>C12-C16

>C16-C21

>C21-C44

>C5-C6

>C6-C8

>C8-C10

>C10-C12

>C12-C16

>C16-C44

H|C

H — C

C|C|H

H — C

C — H

C — H

H — — H

H — C — C — C — C — C — C — C — C — H

H|

H|

H|

H|

|H

|H

|H

|H

H|

|H

H|

|H

H|

|H

H|

|H

Why Did The TPHCWG Go To All This Trouble?

Not all chemicals in crude oil . . . . Not all chemicals in crude oil . . . .

. . . . move the same in the environment. . . . move the same in the environment

Mo

bil

ity

Carbon Number

Adapting the TPHCWG Method for Crude Oil

Crude oils can have 60 to 70% >C35

Modified extraction, separation, and GC detection method

GC extended to C44 compounds

Determined C44+ fraction

Analytical Capability Now Exists to Categorize >85% of Crude Oil Compounds into Fractions

1 2 3 4 5 6 7 8 9 10 11 12 13 14 150

10

20

30

40

50

60

70

80

90

100

Ma

ss

Bal

an

ce

% GC<C6>C44

Different Crude Oils Diesel

Comparison of Composition of Different Crude Oil Products

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

Co

nce

ntr

atio

n (

mg

/kg

)

TPH FractionsAliphaticsAromatics

GasolineMineral OilVaselineCrude Oil

>C

6-C

7

>C

7-C

8

>C

8-C

10

>C

10-C

12

>C

12-C

16

>C

16-C

21

>C

21-C

44

>C

5-C

6

>C

6-C

8

>C

8-C

10

>C

12-C

16

>C

16-C

44

>C

44

Assignment of Toxicity to TPH Fractions

Toxicity data assigned to each fraction of TPH based on available animal toxicity studies

Animal toxicity studies are the same as used by the U.S. EPA

Representative Fraction Toxicity: C5 to C44+

(Non-Carcinogens)

AromaticAromatic AliphaticAliphatic5.0 — Oral18.4 — Inhalation

0.04 — Oral0.02 — Inhalation

0.1 — Oral1.0 — Inhalation

0.03 — Oral 2.0 — Oral

Fraction-Specific RfDs/RfCs (mg/kg/day)

0.03 — Oral 2.0 — Oral

0.03 — Oral 0.8 — Dermal

RangeRange>C5 to C6 aliphatic

>C8 to C10

>C10 to C12

>C12 to C16

>C16 to C21

>C21 to C35

>C35 to C44

>C44+

>C6 to C8 aromatic 0.2 — Oral0.4 — Inhalation

Potential Routes of Exposure for Crude Oil Release at Typical E&P Sites

Groundwater

Impactedshallow soil

Drinking water well

HazardHazard

PeoplePeopleExposure

Exposure

Limiting pathway = surface soil for Vaseline ®, diesel, & crude oilLimiting pathway = soil leaching to groundwater for gasoline

Non-Carcinogenic TPH RBSLs for Hydrocarbon Mixtures

0

20,000

40,000

60,000

80,000

100,000

RB

SL

, T

PH

(m

g/k

g) Vaseline®

Crude Oil

1800 mg/kg

Non-Residential Sites

Vaseline® = 1,000,000 mg/kg

DieselGasoline

33

101099

11

8822

22 33

33

11

22

11

33

Non-Residential TPH RBSLs for Crude Oil in Soils Around the World

0 5 10 15 20 25 30 35 40 45 50API Gravity

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

TP

H N

on

-Res

iden

tial

Su

rfac

e S

oil

RB

SL

, m

g/k

g s

oil

Upper Limit of Existing State Clean-Up Levels

Comparison of Crude Oil Composition of Study Samples to World-Wide Sample Set

50%50%

100%Saturates 50%

100%Resin + Asphaltenes

Aromatics 100%Study Samples

PERF 97-0851 Oils and 6 Soils

World-Wide Sample Set636 Crude Oils

FrequencyDistributionWorld Oils

Conclusions Regarding Risk-Based Approach to E&P Site Management

Protects human health

Uses a rigorous state-of-the-art scientific process

Provides standardized approach

No need to analyze all sites using new analytical technique, but can rely on existing conventional TPH measurement techniques

Commonly Asked Questions

Why have cancer health effects not been addressed?

Why have ecological risks not been addressed?

Do we need to analyze more oils produced in our state?