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National Tanks ConferenceSt. Louis, MOMarch 20, 2012

OverviewVarious forensic techniques available to identify the timing and origin of a contaminant release. Provides convincing information that forms basis for responsible party determination and cost allocation.

PurposeCharacterizes product: Indicates “when – time of release – age dating” ‐ how long has it been there?Determines if product is degrading.

Helps determine responsibility:Identifies “who – source(s)” ‐ which one caused the problem?

Tends to be “holistic”: Interdisciplinary ‐ geochemistry, microbiology and hydrogeology.

In contrast, Site Investigation focuses on evaluating risk and determining “what” and “where”.

Applications• Establish Responsible Party

Identify contributor(s)

• Cost Allocation Contribution to total cost of remedyEquity of allocation

• Due Diligence – Property Transfer(s)Establish “reserves for cleanup – cost to close”

• Insurance Litigation – Toxic TortRelease dateProbability of harm

The Daubert StandardsCourt admissible scientific theory and evidence in environmental legal disputes:

Testable hypothesesPeer reviewDefined error rates and methods of controlGenerally accepted practicesEnvironmental Forensics is scientifically proven –can be used as court admissible evidence.

Tools1. Laboratory Analysis 2. Data Types

IdentificationAge Dating

Formulation of Product –MSDS, etc.Industrial Use – PurposePhysical & Chemical Properties Fate & TransportBusiness Records – shipping, handling, as‐built drawings, utilities, construction photos

Tools3. Aerial Photography 4. Remote Sensing

Establish timing of contaminant release Casual relationship within time period displayed by available photosSequential history of site operationsSources & Pathways: stream channels, barrels, disposal areas, pits, ASTs, drainage ditches, lagoons, or settling ponds, dark stains of known contaminationResults help direct focused sampling of issues of concern

Ecological stresses & stressors (vegetation, water bodies, drainage ponds, etc.)Contaminant Identifications (drums, tanks, disposal pits, landfills, etc.)Distribution of contaminants

Chemical FingerprintingIdentifies the type of hydrocarbon (e.g., diesel, gasoline, jet fuels, kerosene, mineral oil, Stoddard solvent).Age is inferred by:

composition of fuels as a function of the time of formulation.additives associated with a discrete time period.

Determines whether a chemical release was a single event, a series of events, or a continuous release.

Techniques to Identify Age of ReleaseProprietary additives, Antiknock formulations, Trace metals,Degradation models,Chemical profiling.

Chemical Degradation Model –Age Dating Hydrocarbons

Correlates length of time hydrocarbon in subsurface & presence of specific degraded petroleum fractions.Relies on the volatilization and dissolution of BTEX.For GW – B diffuses rapidly out of free‐phase gasoline and partitions into GW followed by T/E/X.For Soil – E/X preferentially retained; more resistant to degradation than B/T.

BT/EX Ratios ExplainedBTEX impacted soils – BT/EX ratio changes (0.8 in the original fuel to 0.4) in five years. BTEX impacted GW – BT/EX ratio decreases exponentially with time because of the preferential transport of B/T.

Increases the less soluble E/X concentrations. Degradation of B & T with time also results in a reduction of the BTEX ratio.

Age Dating Using BT/EX Ratios for Groundwater

Rb = (B + T) / (E + X)(Kaplan et al., 1995, 1997)

Rb range correlation to plume age:1.5 to 6.0 = 1 to 5 years 0.5 to 1.5 = 5 to 10 yearsLess than 0.5 = >10 years(Kaplan and Galperin, 1996)

Improve accuracy by using a best‐fit regression line from historical site data.

BT/EX Ratio VariabilityVolume of releaseInitial gasoline compositionGroundwater chemistryHydrodynamic characteristicsSoil type/textureMicrobial diversityElectron acceptor availabilityAerobic or anaerobic conditions

BTEX Ranges (mg/ml) in Different Grades of Gasolines (Kaplan et. al., GWMR, Fall 1996)

GasolineGrade

Benzene Toluene Ethylbenzene Xylene

Leaded Gasoline

6.6 ‐ 14.8 18.6 ‐ 64.4 6.2 – 14.0 32.1 ‐ 77.4

Regular Unleaded

5.0 ‐ 20.0 17.9 ‐ 44.3 5.8 ‐ 12.0 27.1 ‐ 48.6

Unleaded Plus

7.1 ‐ 17.3 23.9 ‐ 42.6 7.7 ‐ 10.0 37.5 ‐ 50.5

Super Unleaded

6.6 ‐ 23.0 22.4 ‐ 81.0 6.6 ‐ 16.0 33.4 ‐ 65.8

BTEX Ranges in Weathered Gasolines (Kaplan et. al., GWMR, Fall 1996)

GasolineGrade

Benzene Toluene Ethylbenzene Xylene

Free Product (mg/ml)

0.16 ‐ 24.0 0.39 ‐ 100.0 2.1 ‐ 29.0 9.1 ‐ 98.0

Water (µg/ml) 0.02 ‐ 30.3 0.002 ‐ 38.3 0.01 ‐ 5.8 0.005 ‐ 29.6

Soil (µg/g) 0.01 ‐ 10.0 0.01 ‐ 77.4 0.02 ‐ 50.9 0.01 ‐ 220.0

Compound Biodegradation ½ Life (hrs.) for Selected BTEX & PAH @ 25 C (Robert D. Morrison, Ph.D.)

Compound Soil Groundwater

Benzene 120 ‐ 384 240 ‐ 17,280

Toluene 96 ‐ 528 168 ‐ 672

Ethylbenzene 72 ‐ 240 144 ‐ 5,472

o, m, p‐xylene 168 ‐ 672 336 ‐ 8,640

Benzo(a)pyrene 1,368 ‐ 12,720 2,736 ‐ 25,440

Naphthalene 398 ‐ 1,152 24 ‐ 6,192

Pyrene 5,040 ‐ 45,600 10,080 ‐ 91,200

Fingerprinting and Correlation ‐Analytical Methods• Gas Chromatography (GC)• Mass Spectrometry (MS)

Paraffins, Isoparaffins, Aromatics, Napthenes, and Olefins (PIANO)

• Gas chromatography ‐ Isotope Ratio Mass Spectrometry (GCIRMS)

Carbon Ranges of Petroleum Products

GC Fingerprints of Different Petroleum Products

DieselGasoline

JP4Condensate

Biomarker AnalysisBiomarkers, molecular fossils present in an oil, reflect:

1. the relative abundance of oil‐prone vs. gas‐prone organic matter in the source,

2. the source rock age,3. whether the source was deposited in a marine (reducing),

terrestrial‐lacustrine, fluvial‐deltaic (oxidizing) or hyper saline setting,

4. whether the source lithology was a carbonate or shale, and 5. the thermal maturity at which the source rock generated that

oil (e.g., Peters and Moldowan, 1993).

Thus, oils from different basins have different biomarker distributions.

Crude Oil nC17/nC18 ratios

Utilization of Crude Oil BiomarkersSince different potential sources of a spill may involve oil derived from different basins, biomarker distributions can be used to:

1. Rule in or out potential sources of a spill, 2. Determine if oil in a contaminated area actually

represents more than one spill (Stout et al., 2000, 2001).

3. Assess the origin of some refined hydrocarbon products (Peters et al., 1992; Stout et al., 2005).

Chemical ProfilingIdentify the individual components in a soil or liquid sample.Estimate how long a chemical has been in the subsurface.Presence of gaseous hydrocarbons, isobutane, n‐butane, iso‐pentane, and n‐pentane used to determine if product release is "fresh" or "weathered."

Qualitative Indicators for Degradation (Gas & Diesel Chromatograms)Gasoline Diesel

“Fresh” ‐ contain n‐hexane and n‐heptane in higher concentrations than methylcyclohexane (MCH) and n‐octane.“Weathered” ‐MCH concentration increases relative to n‐hexane and n‐heptane.

“Fresh” ‐ n‐alkane compound peaks present.“Weathered” ‐ n‐alkane compound s diminished or non‐existent in weathered diesel.

‐ Other compounds such as pristane and phytane remain.

Consequently, the concentration of these compounds increases as the diesel ages.

Carbon Isotopic Values Crude oils commonly have different carbon

isotopic values that differ with source.

Therefore, carbon isotopic analyses of petroleum releases can be used to:

1. Constrain the source of the contaminant .2. Determine if there is more than one source of oil

in a contaminated area (e.g., Bence et al., 1996).

Isotopic AnalysisUsed for:Dating – radioisotopesProduct Identification – stable isotopes

Stable Isotopes Values Measured in Two Ways (Chemical Fingerprinting):

1. BULK ISOTOPES2. COMPONENT RATIOS

‐ Isotopic compositions of individual compounds

Examples of Stable IsotopesIsotope Uses204Pb/206Pb/207Pb/208Pb13C/12C

Age dating gasoline spillsDistinguish crude oilsDistinguish BTEX sourcesMonitor biodegradation

Example of Bulk Isotope Correlation

Contemporary FP Gasoline releases (2 sources) had similar GC fingerprints but were isotopically distinct due to different source crude oils.

Of Aromatics

Of S

aturates

(Paul Philp, EPA Webinar, Oct. 2010)

Case Study 1:Gas Station

• Problem: Identify Contaminant Type – Age – Source of Impact• Issues of Concern: Vapor Intrusion in down‐gradient buildings, storm sewer and LNAPL found in tank basin observation wells.• Tools: Analytical Examination/GC.• Forensic Evaluation: Evaluate GCs, Octane Rating Index (ORI), Toluene/nC8 ratio, nC6 Olefin scatter/vertical bar plot.• Observations: GC and ORI indicate relatively unaltered RUL from recent manufacture and recent release.nC6 Olefin concentrations are unique and indicate similar cracking/blending units and same refinery.• Conclusion: Gasoline in tank basin wells, product dispensers and storm sewer are identical and from same source and/or release.

Location: Wichita Falls, TX

Case Study 2Bulk Fuel Terminal

• Problem: Identify Source of impact• Issues of Concern: Is product found in onsite wells from on or off0site source – recent or old release.• Tools: Analytical Examination/GC.• Forensic Evaluation: Evaluate GCs, Octane Rating Index (ORI), Toluene/nC8 ratio. nC17/pristane rations, nC12 to nC20 distillate range trail.• Observations: GC plot, ORI consistent of RUL gasoline in both AST sample and MW. Uniformity of small distillate trail nC12 to nC20 in both tank and subsurface sample –regular grade gasoline. Toluene/nC8 ratios indicate a recent release. Isoprenoid plot confirms RUL in AST is genetically the same as subsurface sample.• Conclusion: Gasoline detected in subsurface MWs and in AST is RUL with no PUL detected. Same release and same source.

Location: Montgomery, AL

Case Study 3Gas Station

• Problem: Report of Release• Issues of Concern: New (2010) or old release (2003) and different sources.• Tools: Analytical Examination/GC.• Forensic Evaluation: Evaluate GCs, distillate fraction analysis (nC17 pristane ratios, • Observations: GCs indicate highly degraded and weathered diesel, high sulfur content, release at least 7 years ago. Isoprenoid plot genetically related – came from common source or release.• Conclusion: Commingled plume contains several different aged releases including diesel, gasoline and kerosene but all are from common source.

Location: Amity, AR


• Problem: Identify Responsible Party• Issues of Concern: Is product found in onsite well from old release and responsibility of former tenant• Tools: Analytical Examination/GC.• Forensic Evaluation: Evaluate GCs, Octane Rating Index (ORI), and Toluene/nC8 ratio.• Observations: GC plot indicates that 4 peaks after toluene are regular grade gasoline as well as ORI of 4.2 which indicates regular grade gasoline. Toluene/nC8 ration is 8.6 – indicates manufacture/release date more than 10 years ago.• Conclusion: Gasoline in monitoring well is weathered, and does not show any evidence of a recent release.

Location: Anniston, AL


• Problem: Allocate Costs –Determine Responsible Parties• Issues of Concern: New or old releases and different sources.• Tools: Analytical Examination/GC.• Forensic Evaluation: Evaluate GCs, Toluene/nC8 ratio, distillate fraction analysis (nC17 pristane ratios, isoprenoid plots.• Observations: GCs indicate highly degraded and weathered diesel, gasoline. Toluene/nC8 ratios reveal gasoline (primarily RUL some MUL) released 20 years ago. nC17/pristane ratios indicate 2 releases (20 and 10 years ago). Isoprenoid plots indicates all samples genetically related – came from common source or release.• Conclusion: Commingled plume contains several different aged releases including diesel, gasoline and kerosene but all are from common source.

Location: Tampa, FL


• Problem: Determine Responsible Parties• Issues of Concern: Source of PAHs from Diesel Release or Other Sources• Tools: Historic Aerial Photo Review, Boring Log Evaluation, Analytical Examination/GC.• Forensic Evaluation: Compare present values with historical results• Observations: Construction photos, showing bunt tires, wood chips, asphalt chunks and lab data all indicate that samples genetically related to common anthropogenic source – former landfill burn pit waste.• Conclusion: Only need to sample areas where potential exposure to debris would occur – shallow landscaped areas instead of full blown soil /groundwater PAH delineation.

Location: Hialeah Gardens, FL


1999


2012Mini Race Track

Gas Station

Landfill “Big Box” Store


Debris Removed from Excavation During Construction



Floating Debris in Excavation


ConclusionsIsotopic signature analysis is a key tool in forensic analysis:Distinguishes origins of otherwise similar materials

Indicates “when – time of release – age dating” ‐how long has it been there?Determines if product is degrading.

Tracks materials to common sourceIdentifies “who – source(s)” ‐ which one caused the problem?

Contact InformationLee C. Taylor, P.E.

‐ (407) 864‐1115‐ [email protected]

Dan L. Crawford, P.G.‐ (253) 753‐6024‐ [email protected]

Also Check /Connect to their LinkedIn Profiles

national tanks conference st. louis, mo march 20,...

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