National Tanks Conference St. Louis, MO March 20, 2012

Transcription

1 National Tanks Conference St. Louis, MO March 20, 2012

2 Overview Various 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.

3 Purpose Characterizes 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.

4 Applications Establish Responsible Party Identify contributor(s) Cost Allocation Contribution to total cost of remedy Equity of allocation Due Diligence Property Transfer(s) Establish reserves for cleanup cost to close Insurance Litigation Toxic Tort Release date Probability of harm

5 The Daubert Standards Court admissible scientific theory and evidence in environmental legal disputes: Testable hypotheses Peer review Defined error rates and methods of control Generally accepted practices Environmental Forensics is scientifically proven can be used as court admissible evidence.

6 Tools 1. Laboratory Analysis 2. Data Types Identification Age Dating Formulation of Product MSDS, etc. Industrial Use Purpose Physical & Chemical Properties Fate & Transport Business Records shipping, handling, as built drawings, utilities, construction photos

7 Tools 3. Aerial Photography 4. Remote Sensing Establish timing of contaminant release Casual relationship within time period displayed by available photos Sequential history of site operations Sources & Pathways: stream channels, barrels, disposal areas, pits, ASTs, drainage ditches, lagoons, or settling ponds, dark stains of known contamination Results 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

8 Chemical Fingerprinting Identifies 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.

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

10 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.

11 BT/EX Ratios Explained BTEX 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.

12 Age Dating Using BT/EX Ratios for Groundwater R b = (B + T) / (E + X) (Kaplan et al., 1995, 1997) R b range correlation to plume age: 1.5 to 6.0 = 1 to 5 years 0.5 to 1.5 = 5 to 10 years Less than 0.5 = >10 years (Kaplan and Galperin, 1996) Improve accuracy by using a best fit regression line from historical site data.

13 BT/EX Ratio Variability Volume of release Initial gasoline composition Groundwater chemistry Hydrodynamic characteristics Soil type/texture Microbial diversity Electron acceptor availability Aerobic or anaerobic conditions

14 BTEX Ranges (mg/ml) in Different Grades of Gasolines (Kaplan et. al., GWMR, Fall 1996) Gasoline Grade Leaded Gasoline Regular Unleaded Unleaded Plus Super Unleaded Benzene Toluene Ethylbenzene Xylene

15 BTEX Ranges in Weathered Gasolines (Kaplan et. al., GWMR, Fall 1996) Gasoline Benzene Toluene Ethylbenzene Xylene Grade Free Product (mg/ml) Water (µg/ml) Soil (µg/g)

16 Compound Biodegradation ½ Life (hrs.) for Selected BTEX & 25 C (Robert D. Morrison, Ph.D.) Compound Soil Groundwater Benzene ,280 Toluene Ethylbenzene ,472 o, m, p xylene ,640 Benzo(a)pyrene 1,368 12,720 2,736 25,440 Naphthalene 398 1, ,192 Pyrene 5,040 45,600 10,080 91,200

17 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)

18 Carbon Ranges of Petroleum Products

19 GC Fingerprints of Different Petroleum Products Condensate JP4 Gasoline Diesel

20 Biomarker Analysis Biomarkers, 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.

21 Crude Oil nc17/nc18 ratios

22 Utilization of Crude Oil Biomarkers Since 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).

23 Chemical Profiling Identify 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."

24 Qualitative Indicators for Degradation (Gas & Diesel Chromatograms) Gasoline 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. Diesel Fresh n alkane compound peaks present. Weathered n alkane compound s diminished or nonexistent in weathered diesel. Other compounds such as pristane and phytane remain. Consequently, the concentration of these compounds increases as the diesel ages.

25 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).

26 Isotopic Analysis Used for: Dating radioisotopes Product Identification stable isotopes Stable Isotopes Values Measured in Two Ways (Chemical Fingerprinting): 1. BULK ISOTOPES 2. COMPONENT RATIOS Isotopic compositions of individual compounds

27 Examples of Stable Isotopes Isotope 204Pb/206Pb/207Pb/208Pb 13C/12C Uses Age dating gasoline spills Distinguish crude oils Distinguish BTEX sources Monitor biodegradation

28 Example of Bulk Isotope Correlation Of Saturates (Paul Philp, EPA Webinar, Oct. 2010) Of Aromatics Contemporary FP Gasoline releases (2 sources) had similar GC fingerprints but were isotopically distinct due to different source crude oils.

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33 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

34 Case Study 2 Bulk 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

35 Case Study 3 Gas 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

36 Case Study 4 Bulk Fuel Terminal 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

37 Case Study 5 Bulk Fuel Terminal 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

38 Case Study 6 Gas Station 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

39 Case Study 6 Gas Station Landfill Location: Hialeah Gardens, FL Big Box Store 1999 Mini Race Track 2012 Gas Station

40 Case Study 6 Gas Station Location: Hialeah Gardens, FL Debris Removed from Excavation During Construction

41 Case Study 6 Gas Station Location: Hialeah Gardens, FL Floating Debris in Excavation

42 Conclusions Isotopic 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 source Identifies who source(s) which one caused the problem?

43 Contact Information Lee C. Taylor, P.E. (407) Dan L. Crawford, P.G. (253) Also Check /Connect to their LinkedIn Profiles