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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/foc
< 130 µmoles/goc
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/foc
values well below 3,000 µmoles/goc
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/foc
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
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. 86th
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
Subaqueous
capping of contaminated sediments is highlighted in the
EPA Sediment Remediation Guidance (EPA, 2005) and often
offers a cost effective alternative to dredging that
addresses risk. Subaqueous
caps require knowledge of a prescribed set of key design
variables to predict performance, including; groundwater
seepage rate, pore water concentration of dissolved
constituents, existence of indigenous microbes and their
degradation rates, and physical migration of NAPL due to
cap construction. This is especially important where coal
tar in the form of NAPL is the contaminant driving a
remediation. This
paper explains how these variables can be determined,
illustrates the links between them, and shows how they
impact cap design at coal tar sites.
Insight into these and other variables has been the
subject of on-going research efforts by Purdue University,
and this paper presents a summary of those findings.
A new type of flux meter, developed and field
tested, in cooperation with the USEPA Office of Research
and Development is described.
This simple flux meter; produces virtually no
resistance to flow; addresses gas generation, NAPL
migration, and isolation from river flow; and develops
high quality repeatable field data.
The equilibrium distributions, between the water,
and MAH and PAH fractions of coal-tar contaminated
sediment have been measured and evaluated for consistency
with a Raoult’s Law-based quantitative relationship,
which allows for the calculation of pore water
concentration based on the solubility and mole fraction
concentration of the compound within the liquid coal tar.
The presence of indigenous microbes capable of
degrading coal tar constituents and their ability to be
revived to colonize a cap are demonstrated.
Lastly, a series of experiments to assess NAPL
migration into the cap were performed to increase
confidence in determining cap thickness.
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