The Types and Weathering States of PCB Mixtures in New Bedford Harbor Sediments Revealed by Environmental Forensic Methodology
Stephen Emsbo-Mattingly, Battelle Memorial Institute, Duxbury, MA
Helen Douglas, Foster Wheeler Environmental Corporation, Boston, MA

VOCs Measured in Sodium Bisulfate and Methanol Preserved Samples (Method 5035) and Risk Characterization Impacts
Patrick P. King, GEI Consultants, Inc., Winchester, MA
Michael D. Walters, Polaroid Corporation, Waltham, MA 

Evaluation of Light Non-aqueous Phase Liquid Weathering Rates at Various Fuel Release Sites
Daniel R. Griffiths, Parsons, Denver, CO
Bruce M. Henry, Parsons, Denver, CO
Douglas C. Downey, Parsons, Denver, CO
Jerry E. Hansen, AFCEE/ERT, Brooks AFB, TX

Chemical Fingerprinting of Weathered Middle Distillate Fuels Using Bicyclic Sesquiterpanes
Scott A. Stout, Ph.D., BATTELLE, Duxbury, MA
Kevin J. McCarthy, BATTELLE, Duxbury, MA
Allen D. Uhler, Ph.D., BATTELLE, Duxbury, MA 

MTBE and its Degradation Products: Molecular Modeling Study
Krishna L. Bhat, Philadelphia University, Philadelphia, PA  
Seth Hayik, Philadelphia University, Philadelphia, PA   
Charles W. Bock, Philadelphia University, Philadelphia, PA 
William H. Brendley, Jr., Philadelphia University, Philadelphia, PA 

Environmental Fate and Transport Modeling of Explosives and Propellants in the Saturated Zone
Diane M. Curry, AMEC Earth & Environmental, Westford, MA
Jacob Zaidel, AMEC Earth & Environmental, Westford, MA
Al Laase, AMEC Earth & Environmental, Westford, MA
Jay L. Clausen, AMEC Earth & Environmental, Westford, MA Dave Hill, MAARNG, Camp Edwards, MA  

Stephen Emsbo-Mattingly, Battelle Memorial Institute, 397 Washington Street, Duxbury, MA 02332 Tel: 781-952-5246
Helen Douglas, Foster Wheeler Environmental Corporation, 133 Federal Street – 6^th Floor, Boston, MA 02110, Tel: 617-457-8263

Environmental forensic tools describe well the types and weathering patterns of PCB mixtures in the environment.  The forensic approach assists many projects historically governed by conservative assumptions about PCB composition, because the site-specific PCB type(s) and weathering processes (anaerobic dechlorination, dissolution, and volatilization) can affect the toxicity and remediation endpoints.  For example, the anaerobic dechlorination of a PCB mixture, like Aroclor 1242, can 1) selectively remove more toxic PCB congeners, 2) generate less toxic PCBs, and 3) promote the net reduction of PCBs through dissolution and evaporation.  This paper presents forensic methodology for identifying and interpreting site-specific PCB compositions.

Recent PCB measurements of approximately 1000 samples (sediment, water and air) collected from New Bedford Harbor, Massachusetts (NBH) will illustrate the forensic approach for identifying the types and weathering states of selected Aroclor mixtures.  These data were generated by high resolution gas chromatographs (GC) equipped with several PCB detectors.  These detectors included a low resolution mass spectrometer (LRMS), high resolution mass spectrometer (HRMS), and electron capture detector (ECD).  The forensic analytical tools featured in this presentation include PCB congener and homologue fingerprints, principal components analysis (PCA), and diagnostic ratio plots.  These techniques were used to compare and contrast recent data with historical studies of weathering at NBH and other PCB contaminated sites, like Hudson River, NY and Silver Lake, MA.

VOCs Measured in Sodium Bisulfate and Methanol Preserved Samples (Method 5035) and Risk Characterization Impacts

Patrick P. King, GEI Consultants, Inc., 1021 Main Street, Winchester, MA 02144, Tel: 781-721-4000, Fax: 781-721-4073
Michael D. Walters, Polaroid Corporation, 1265 Main Street, W2-Mezz, Waltham, MA 02451, Tel: 781-386-0875, Fax: 781-386-0880

Order of magnitude differences in volatile organic compound (VOC) concentrations were measured in split-samples collected in accordance with EPA Method 5035 and preserved using sodium bisulfate and methanol.  Resolving these concentration differences was critical to the assessment of human health and ecological risk at two example sites. 

Soil and sediment samples were collected from two sites and duplicate portions were preserved with sodium bisulfate and methanol.  VOC concentrations measured in the methanol preserved portions were often more than an order of magnitude higher than VOC concentrations measured in the sodium bisulfate preserved portions of the samples.  By giving consideration to what these different data represented, these differences were addressed in the risk characterizations prepared for each of the sites.  The greater extraction efficiency of methanol preservation yielded a better measure of the total contaminant mass while, under some circumstances, sodium bisulfate preservation provided a more direct measure of the contamination available to receptors.  Tools for predicting VOC concentrations for sodium bisulfate preserved samples using data from methanol preserved samples and vice-versa are presented.

Evaluation of Light Non-aqueous Phase Liquid Weathering Rates at Various Fuel Release Sites

Daniel R. Griffiths, Parsons, 1700 Broadway, Suite 900, Denver, Colorado 80290,Tel: 303-831-8100, Fax: 303-831-8208 Email: daniel.r.griffiths@parsons.com
Bruce M. Henry, Parsons, 1700 Broadway, Suite 900, Denver, Colorado 80290, Tel: 303-831-8100, Fax: 303-831-8208 Email: bruce.henry@parsons.com
Douglas C. Downey, Parsons, 1700 Broadway, Suite 900, Denver, Colorado 80290, Tel: 303-831-8100, Fax: 303-831-8208 Email: doug.downey@parsons.com
Jerry E. Hansen, AFCEE/ERT, 3207 North Road, Bldg 532, Brooks AFB, Texas 78235-5363, Tel: 210-536-4353, Fax: 210-536-4330, Email: jerry.hansen@brooks.af.mil

Large-volume environmental releases of fuels have contaminated and continue to contaminate soil and groundwater at many government and commercial sites across the United States.  Uncontrolled catastrophic or chronic releases of fuel products can result in large volumes of fuel being released to the subsurface.  Fuels released to the subsurface typically persist as both residual and mobile light non-aqueous phase liquid (LNAPL).  Mobile LNAPL is often targeted for remediation as the primary source of contaminant mass and because mobile LNAPL can be remediated to a limited extent.  Residual LNAPL trapped in the subsurface is extremely difficult to remediate and continues to act as a secondary source of contaminants to soil, soil vapor, and groundwater as long as the residual LNAPL persists.  Of the fuels related contaminants, benzene, ethylbenzene, toluene, and xylenes (BTEX) are of primary importance because of their relatively high solubility and mobility in groundwater, and their relative toxicity (particularly benzene).  Little information is available regarding natural weathering rates of the BTEX components from mobile fuel LNAPLs.  As a result, contaminant source term reduction rates in contaminant transport models are left to professional judgment with little, or no, scientific basis.  The application of overly conservative LNAPL weathering rates negatively impacts the feasibility and cost of implementing monitored natural attenuation (MNA), while the application of inflated weathering rates can lead to an overly optimistic forecast of MNA performance.  Parsons and the Air Force Center for Environmental Excellence (AFCEE) have analyzed and calculated natural LNAPL weathering rates for BTEX compounds at multiple sites contaminated with mobile LNAPL.  Calculated first order weathering rates for benzene and total BTEX are often as high as 20 percent per year.  Results of these analyses will be presented in order to improve the scientific basis of, and defensibility for, BTEX source reduction rates. 

Chemical Fingerprinting of Weathered Middle Distillate Fuels Using Bicyclic Sesquiterpanes

Scott A. Stout, Ph.D., Kevin J. McCarthy, and Allen D. Uhler, Ph.D., BATTELLE, 397 Washington St., Duxbury, MA  02332, Tel: 781-934-0571, Fax: 781-934-2124

Recognizing distinct types or sources of middle distillate fuels in environmental matrices after weathering has left little more than a non-distinctive ‘hump’, or unresolved complex mixture.  This paper describes weathering resistant compounds known as bicyclic sesquiterpanes, which occur in middle distillate fuels (boiling between approximately 240^oC to 285^oC).  These compounds can provide specific information about the nature of these fuels, even after environmental weathering has occurred.  Bicyclic sesquiterpanes are, as their name implies, bicycloparaffins containing approximately 15 (‘sesqui-’) carbons.  These compounds (i.e., C₄ to C₆-decalins) have molecular weights ranging from approximately 194 to 222 amu.   Analysis of liquid petroleum products or petroleum-impacted soil extracts by gas chromatography-mass spectrometry (GC/MS; full scan or selected ion monitoring) reveals these compounds on the m/z 123 mass chromatogram, due to production of a strong C₉H₁₅⁺ fragment.   Data are presented which reveals the variety of sesquiterpane patterns that can exist in distillate petroleum products.  These differences are reasonably attributed to the differences in the crude oil feedstocks used in the production of these different fuels, although some influence of distillation can affect sesquiterpane patterns, depending on the end-boiling points of the petroleum product.  Data are presented that demonstrate the consistency in the distribution of sesquiterpanes over a wide range of weathering over environmental timescales.  Finally, a case study is presented in which the sesquiterpanes are used to unravel the source of weathered diesel fuel #2 impacting soils on adjacent properties. 

MTBE and its Degradation Products:  Molecular Modeling Study

Krishna L. Bhat, Assistant Professor, Chemistry, School of Science and Health, Philadelphia University, School House Lane and Henry Ave., Philadelphia, PA  19144-5497, Tel: 215-951-2878, Fax:  215-951-6812, E-mail:  bhatk@philau.edu   Seth Hayik, Senior Undergraduate Student (Biochemistry major), School of Science and Health, Philadelphia University, Tel:  215.951.2548, Email:  hayik2@philau.edu
Charles W. Bock, Professor, Computational Chemistry, School of Science and Health, Philadelphia University, School House Lane and Henry Ave., Philadelphia, PA  19144-5497, Tel: 215-951-2878, Fax:  215-951-6812 Email:  bockc@philau.edu
William H. Brendley, Jr., Dean and Professor of Chemistry, School of Science and Health, Philadelphia University, School House Lane and Henry Ave., Philadelphia, PA  19144-5497, Tel: 215-951-2648,  Fax:  215-951-6812, Email:  brendleyw@philau.edu

MTBE is the most commonly used fuel oxygenate because of its high octane rating, the ability to dilute undesirable gasoline components, low production costs, ease of blending with gasoline, and ease of transfer and distribution.  While much is known about the biodegradation of many gasoline components under both aerobic and anaerobic conditions, the pathway(s) responsible for biodegradation of MTBE have not been fully elucidated.  We have examined computationally the thermodynamics and kinetic parameters for several reactions that are involved in the biodegradation of MTBE ultimately leading to the formation of carbon dioxide and water.  The results of semiempirical, molecular orbital and density functional theory calculations on MTBE and a variety of its possible degradation products will be presented.  These calculations employed the modeling packages CAChe, Spartan, and GAUSSIAN 98 and were performed on Silicon Graphics workstations.

Environmental Fate and Transport Modeling of Explosives and Propellants in the Saturated Zone

Diane M. Curry, Jacob Zaidel, Al Laase, and Jay L. Clausen, AMEC Earth & Environmental, 239 Littleton Road, Suite 1B, Westford, MA 01886, Tel: 978-692-9090, Fax: 978-692-6633
Dave Hill, MAARNG, Impact Area Groundwater Study Program Office, PB 565/567 West Outer Road, Camp Edwards, MA 02542

Fate and Transport modeling of explosives was conducted at the Demolition Area 1 site at the Massachusetts Military Reservation.  The objectives of the modeling were to (1) assess the future groundwater plume configuration and  (2) conduct capture zone analysis to assess various remedial alternatives.  MODTMR was used to develop a subregional model for Demolition Area 1 from a regional model of Western Cape Cod.  Saturated zone flow modeling was conducted using MODFLOW with particle tracking conducted using MODPATH.  Transport simulations were conducted using MT3D.  Model results indicate the mobility potential of the explosives and propellants varies depending on the chemical structure. 

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