Application of the USEPA's Equilibrium Partitioning Sediment Benchmark (ESB) Methods for Evaluating Metal Bioavailability and Toxicity in Lower Hudson River Sediments
Ken Jenkins, BBL Sciences, Petaluma, CA

Sampling Methods and Techniques for Quantifying AVS/SEM and Metals Bioavailability in Esturine Sediments
Caryn Kiehl-Simpson, Parsons, Williamsville, NY

Performance Comparisons of Geostatistical Approaches for Delineating Sediment Contamination
John Wolfe, Limno-Tech, Inc., Ann Arbor, MI

The Influence of Carbonaceous Organics on the Sampling, Analysis, and Remediation of PAH Contaminated Harbor Sediment
Lawrence Zanko, University of Minnesota Duluth, Duluth, MN

Sediment Equilibrium Partitioning Benchmarks for Energetic Compounds: A Cautionary Note and Alternate Approaches
Daniel S. Jones, ARCADIS G&M Inc., Knoxville, TN

Technical Challenges on the Marine Hydraulic Dredging Activities, New Bedford Harbor Superfund Site
Caroline S. Roberts, Jacobs Engineering Group, Inc., Bourne, MA
Kenneth C. Gaynor, Jacobs Engineering Group, Inc., New Bedford, MA

Subaqueous Capping Considerations for Coal Tar Contaminated Sediments
Brian B. Johnson, Sevee & Maher Engineers, Inc., Cumberland Center, ME

Application of the USEPA’s Equilibrium Partitioning Sediment Benchmark (ESB) Methods for Evaluating Metal Bioavailability and Toxicity in Lower Hudson River Sediments

Kenneth D. Jenkins, BBL Sciences, 1670 Corporate Circle, Suite 200, Petaluma, CA, 94954, Tel: 707-776-0865, Fax: 707-776-0850, Email: kjenkins@bbl-inc.com
Philip E. Goodrum, BBL Sciences, 6723 Towpath Road, Syracuse, NY, 13214, Tel: 315-446-9120, Fax: 315-449-0017, pgoodrum@bbl-inc.com
Caryn E. Kiehl-Simpson, Parsons, 180 Lawrence Bell Drive, Suite 104 Williamsville, NY, 14221, Tel: 716-633-7074, Fax: 716-633-7195, Email: caryn.kiehl@parsons.com
Steven L. Huntley, BBL Sciences, 1670 Corporate Circle, Suite 200, Petaluma, CA, 94954, Tel: 707-776-0865, Fax: 707-776-0850, Email: shuntley@bbl-inc.com

The U.S. Environmental Protection Agency (USEPA) recently published its final guidance for evaluating the bioavailability and toxicity of metals in sediments using equilibrium partitioning sediment benchmarks (ESBs).  The ESB methodology accounts for the sequestering of metals by acid volatile sulfides (AVS), organic carbon (OC), and other solid-phase and dissolved-phase ligands naturally present in sediments thus limiting their bioavailability and toxicity to benthic organisms.  Specifically, the ESB guidance provides quantitative methods for evaluating the binding capacity of AVS and OC relative to the sum of the simultaneously extracted metal (∑SEM) concentrations for six metals (cadmium, copper, lead, nickel, silver, and zinc), whereby when ∑SEM-AVS < 0 µmoles/g or when ∑SEM-AVS/f_oc < 130 µmoles/g_oc then these metals are fully bound and not bioavailable to benthic organisms and toxicity is not observed.  To evaluate potential metals toxicity in Lower Hudson River sediments near a former copper cable manufacturing facility, 50 near-surface sediment samples were collected in November 2004 and November 2005 and analyzed for bulk sediment metals, AVS, SEM, total organic carbon (TOC), oxidation/reduction (redox) potential, and grain size.  Application of the ESB methodology showed that the concentrations of AVS and TOC were sufficient to sequester these metals at ∑SEM-AVS/f_oc values well below 3,000 µmoles/g_oc where toxicity would be predicted if exceeded.  Although these data indicate substantial metals binding capacity, variability in AVS concentrations was observed both spatially and with depth.  Based on mechanistic considerations, the most likely factors influencing AVS variability include sediment depth, redox potential, and grain size.  The effects of these variables on the ∑SEM-AVS/f_oc were further evaluated as was the applicability of the ESB method in establishing site-specific remedial goals for metals.

Sampling Methods and Techniques for Quantifying AVS/SEM and Metals Bioavailability in Estuarine Sediments

Caryn Kiehl-Simpson, Parsons, 180 Lawrence Bell Drive, Suite 104, Williamsville, NY 14221
Ken Jenkins, BBL Sciences, 1670 Corporate Circle Suite 200, Petaluma, CA 94954-9621

Recent (2005) USEPA guidance provides procedures for assessing metals bioavailability and toxicity based on concentrations of acid volatile sulfides (AVS) and total organic carbon (TOC).  Studies have shown that sediments throughout the Hudson-Raritan Estuary, including the Lower Hudson contain sufficient AVS to limit bioavailability and toxicity.  Sediment sample collection and laboratory analysis methods were developed to evaluate metal bioavailability/toxicity in sediments adjacent to a former cable manufacturing facility on the Lower Hudson River.   

Accurate evaluation of the actual in situ concentrations of AVS and simultaneously extracted metals (SEM) required sampling, handling, analysis techniques that would maintain the in situ redox conditions.  Guidance for collecting and handling of samples for AVS/SEM analyses is limited.  Therefore, techniques were developed for collecting and processing representative sediment samples while minimizing changes to in situ redox conditions.  The sampling procedures permitted the measurement of redox potential in the field and allowed for a relatively large representative volume of sample to be collected for analysis so that low analytical detection limits could be achieved.  The sampling procedure made use of readily available sediment sampling tools and handling/management techniques that could be executed immediately upon sample collection. These techniques minimized handling and also allowed for visual examination of the surficial sample to note color changes in the sediment profile and/or the production of gas bubbles in the core.  Following sample collection, special care was taken during transport and in the lab to ensure that the sample was carried through analysis without exposure to oxidizing conditions, thus emulating conditions as close to those existing in the subsurface as possible and producing representative concentrations of AVS/SEM and metals in porewater. These methods are discussed and compared with recent USEPA guidance.  The results from this study are presented in more detail in a separate presentation.    

Keywords:  AVS, SEM, porewater metals

Performance Comparisons of Geostatistical Approaches for Delineating Sediment Contamination

John Wolfe, Limno-Tech, Inc., 501 Avis Drive, Ann Arbor, Michigan 48108
Noemi Barabas, Limno-Tech, Inc., 501 Avis Drive, Ann Arbor, Michigan 48108
Todd Thornburg, Anchor Environmental, Anchor Environmental, LLC, 6650 SW Redwood Lane, Suite 110, Portland, OR 97224

The relative performance of alternate interpolation methods for delineating sediment remediation areas, volumes, and dredge cuts was evaluated as part of the remedial design effort on a major Superfund remediation site.  The methods evaluated included Thiessen polygons, a hybrid of ordinary kriging and indicator kriging, and full indicator kriging, with and without channel straightening.  Full indicator kriging methods provide estimates of depth of contamination at varying levels of significance, defined as the risk of leaving contaminated sediment behind (false negative error).  This type of error is balanced against the risk of unnecessarily dredging clean material (false positive error), to inform risk management decisions.  Performance of alternative methods, as well as performance of the full indicator kriging method at a range of significance levels, was compared using cross-validation metrics.  These metrics included sensitivity, specificity, false positives, false negatives, bias, mean absolute error, and root mean squared error.  The hybrid ordinary/indicator kriging method and the full indicator kriging method showed excellent agreement and very comparable performance metrics; however, full indicator kriging showed less attenuation of extreme values (i.e., overestimation of shallowest areas, and underestimation of deepest areas.  River straightening further improved performance.  The use of the interpolations as the basis for dredging design, and applications of similar techniques to other contaminated sediment sites, will also be discussed.

The Influence of Carbonaceous Organics on the Sampling, Analysis, and Remediation of PAH Contaminated Harbor Sediments

Lawrence M. Zanko, Research Fellow, Economic Geology Group, Natural Resources Research Institute, University of Minnesota Duluth, 5013 Miller Trunk Highway, Duluth, MN 55811, Tel: 218-720-4274, Email: lzanko@nrri.umn.edu
J. Kenneth Wittle, Electro-Petroleum, Inc., 996 Old Eagle School Rd., Wayne, PA 19087, Tel: 610-687-9070, Email:  Kwittle@electropetroleum.com

Studies by Means (1980), Talley et al (2002), and Ghosh et al (2004) have shown that particulate organic matter can play a prominent role in the adsorption and bioavailability of soil and sediment contaminants like polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs).  An ongoing evaluation of a pilot-scale harbor sediment remediation project conducted in Duluth, Minnesota, since 2002 has highlighted the technical challenge of treating a heterogeneous sediment matrix that contains significant amounts of such particulate matter, i.e., carbonaceous organics like coal tar, coal, and vegetation.   The pilot project has tested and evaluated an electrochemical remediation technology developed by Electro-Petroleum, Inc. of Wayne, PA, and electrochemical processes, llc Stuttgart, Germany.  The technology, called Electro Chemical Geo-Oxidation (ECGO), has been applied to dredged harbor sediments contaminated with moderate levels, e.g., 150ppm to 200ppm, of PAHs in both a simulated submerged and heaped application.

Analytical results from the Duluth project illustrate two major findings related to the influence of particulate organics.  First, the results appear to suggest that previously non-extractable PAHs, i.e., those strongly adsorbed to coal or other organic/carbonaceous particles (and therefore non-detectable by typical PAH analytical techniques), can be converted to an extractable (and therefore detectable) form via a desorption mechanism imparted by the ECGO process.   Second, particles of coal tar present within the sediment contribute to a significant PAH “nugget effect” especially when the PAH concentration in the nugget is grater than 7.5 % of the nugget mass. If one follows EPA sampling protocols the larger “nuggets” may be removed from the sample prior to send to the laboratory for analysis.  This nugget effect impacts sampling strategies, complicates the interpretation of analytical results, and even calls into question how meaningful those analytical results are from a remediation evaluation and regulatory perspective.

We discuss these analytical findings and our overall Duluth experience in greater detail, and offer strategies for how similar sediments and soils should be sampled, analyzed, and treated in future remediation projects.

Sediment Equilibrium Partitioning Benchmarks for Energetic Compounds: A Cautionary Note and Alternate Approaches

Daniel S. Jones, ARCADIS G&M Inc., 114 Lovell Road, Suite 202, Knoxville, Tennessee 37934, Tel: 865.675.6700, Fax: 865.675.6712, Email: dsjones@arcadis-us.com
Christopher C. Lutes, ARCADIS G&M Inc., 4915 Prospectus Dr., Suite F, Durham NC 27713, Tel: 919-544-4535, Fax: 919-544-5690, Email: clutes@arcadis-us.com

The ecological risk assessment process uses ecological screening values (benchmarks) to identify constituents of potential ecological concern (COPECs).  The relative lack of sediment screening values for energetics and other polar non-ionic compounds has led to the use of the equilibrium partitioning (EqP) method for the derivation of benchmarks. That method is intended for use with organic compounds for which hydrophobicity dominates the pore water-to-particle partitioning relationship.  However, other intermolecular forces may increase the partitioning to sediment particulates for compounds with a low octanol-water partition coefficient (log Kow), such that the EqP model may substantially overestimate the potential for exposure (and therefore risks). A recent EPA procedure for deriving EqP benchmarks states that this method should be applicable to nonionic organic chemicals with a Kow above 3.0.  Yet some published sediment screening values include EqP benchmarks for nitroaromatic explosives and other chemicals with log Kow values less than 3.  The resulting benchmarks are on the order of 10 to 100 parts-per-billion in whole sediment.  The unrestricted use of such conservative benchmarks may lead to limited resources being wasted on detailed evaluations or remediation of spurious COPECs.  Alternative approaches for evaluating sediment concentrations of energetic compounds include using literature-derived Kd values for similar systems, measuring site-specific pore water concentrations, and performing site-specific biological tests.  Understanding the factors that influence partitioning of these compounds will help the risk assessor evaluate the uncertainties associated with the available benchmarks and alternative methods of evaluation.

Technical Challenges on the Marine Hydraulic Dredging Activities, New Bedford Harbor Superfund Site

Kenneth C. Gaynor, Jacobs Engineering Group, Inc., 103 Sawyer Street, New Bedford, MA, 02746, Tel: 508-996-5462 ext 201, Fax: 508-996-6742, Email: ken.gaynor@jacobs.com
Caroline S. Roberts, Jacobs Engineering Group, Inc., 6 Otis Park Drive, Bourne MA 02532-3870, Tel: 508-743-0214 ext. 255, Fax: 508-743-9177, Email: caroline.roberts@jacobs.com
Carl L. Wilson, Jacobs Engineering Group, Inc., 103 Sawyer Street, New Bedford, MA 02746, Tel: 508-996-5462 ext 206, Fax: 508-996-6742, Email: carl.wilson@jacobs.com
Steven Fox, Jacobs Engineering Group, Inc., 103 Sawyer Street, New Bedford, MA 02746, Tel: 508-996-5462 ext 211, Fax: 508-996-6742, Email: steven.fox@jacobs.com
Terence Driscoll, Sevenson Environmental Services, Inc., 2749 Lockport Road, Niagara Falls, NY, 14305, T 716-284-0431, F 716-284-7645, Email: tpdriscoll@mindspring.com

Jacobs Engineering Group, Inc. (Jacobs) and Sevenson Environmental Services, Inc. (Sevenson) are conducting remedial activities at the New Bedford Harbor Superfund Site (Site) under contract with the US Army Corps of Engineers (USACE). Funding and oversight for this project is provided by the US Environmental Protection Agency (EPA) through the national Superfund Program. The Site is located in Bristol County, Massachusetts, approximately 55 miles south of Boston.  Contamination at the Site consists of marine sediments impacted by polychlorinated biphenyls (PCBs) and heavy metals from industrial activities adjacent to the shoreline.

The selected remedial alternative for the Site involves hydraulic dredging for removal of the PCB-impacted sediment.  Following removal, the remedy includes sand separation, sediment dewatering, wastewater treatment, and sediment transportation to an offsite disposal facility.

In 2004 and 2005, the Team (Jacobs, Sevenson, USACE and EPA) solved a number of technical challenges related to dredging in this unique marine setting.  Hydrogen sulfide (H₂S) gas at concentrations exceeding current permissible exposure levels was immediately released from the marine sediments upon initiation of dredging and processing.  The elevated H₂S concentrations were mitigated through engineering controls consisting of chemical treatment and local exhaust ventilation.  Ferric sulfate (Fe₂(SO₄)₃) was injected  into the dredge slurry to reduce or eliminate H₂S by precipitating ferric sulfide (FeS).  Slotted hoods were installed to capture any un-reacted H₂S. A second challenge involved maintaining the required dredge production despite the presence of urban debris embedded in the sediment.  To overcome this challenge unique equipment was designed to remove the debris while maintaining the low water column turbidity thresholds established for environmental protection.  A third challenge presented to the Team was the accurate monitoring of the vertical and horizontal progress of the dredging in the shallow tidal marine setting.  This was accomplished by using a combination of tools, including a Global Positioning System (GPS), laser level soundings, and acoustic bathymetric surveys.

Resolving these technical challenges allowed the Team to reduce the risk of personal injury and increase overall productivity.  The lessons learned on the New Bedford dredging program can be applied to other freshwater and marine dredging environments where success is measured not only in sediment removal rates per day, but in worker safety metrics and process quality control.

Subaqueous Capping Considerations for Coal Tar Contaminated Sediments

Brian B. Johnson, Sevee & Maher Engineers, Inc, 4 Blanchard Road, Cumberland Center, Maine 04021, Tel: 207-829-5016, Fax: 207-829-5692, Email: bbj@smemaine.com
Chad T. Jafvert, Purdue University, School of Engineering, 550 Stadium Mall Drive, West Lafayette, IN  47907-2051, Tel: 765- 494-2196, Fax: 765-496-1107, Email: jafvert@ecn.purdue.edu
Joe Ferry, NiSource Corporate Services Company; 801 E. 86^th Avenue, Merrillville, IN 46410, Tel: 614-460-4849, Fax: 614-460-6971, Email: jferry@nisource.com
Byron Jenkinson, Jenkinson Environmental Services, LLC., 5240 West, 350 North, West Lafayette, IN 47906, Tel: 765-583-2703, Fax: 765-583-4217, Email: bjenkins@dcwi.com
Seunghun Hyun, Purdue University; School of Engineering, 550 Stadium Mall Drive, West Lafayette, IN  47907-2051, Tel: 765- 494-2196, Fax: 765-496-1107, Email: hyun@purdue.edu
Paul Exner, NiSource Corporate Service Company; 300 Friberg Parkway, Westborough, MA 01581, Tel: 508-836-7256, Fax: 508-836-7073, Email: pexner@nisource.com

Top