Sediments

Valence state: The combining capacity of an atom or radical determined by the number of electrons that it will lose, add, or share when it reacts with other atoms.

Source: The American Heritage™ Dictionary of the English Language, Fourth Edition
Copyright © 2000 by Houghton Mifflin Company.

free product: A NAPL found in the subsurface in sufficient quantity that it can be partially recovered by pumping or gravity drain.

aerobic: Direct aerobic metabolism involves microbial reactions that require oxygen to go forward. The bacteria uses a carbon substrate as the electron donor and oxygen as the electron acceptor. Degradation of contaminants that are susceptible to aerobic degradation but not anaerobic often ceases in the vicinity of the source zone because of oxygen depletion. This can sometimes be reversed by adding oxygen in the form of air (air sparging, bioventing), ozone, or slow oxygen release compound (e.g., ORC(r)).

Aerobic dechlorination may also occur via cometabolism where the dechlorination is incidental to the metabolic activities of the organisms. In this case, contaminants are degraded by microbial enzymes that are metabolizing other organic substrates. Cometabolic dechlorination does not appear to produce energy for the organism. At pilot- or full-scale treatment, cometabolic and direct dechlorination may be indistinguishable, and both processes may contribute to contaminant removal. For aerobic cometabolism to occur there must be sufficient oxygen and a suitable substrate which allows the microbe to produce the appropriate enzyme. These conditions may be present naturally but often in the presence of a source area oxygen and a substrate such as methane or propane will need to be introduced.

Adapted from US. EPA 2006 Engineering Issue: In Situ and Ex Situ Biodegradation Technologies for Remediation of Contaminated Sites

anaerobic: Direct anaerobic metabolism involves microbial reactions occurring in the absence of oxygen and encompasses many processes, including fermentation, methanogenesis, reductive dechlorination, sulfate-reducing activities, and denitrification. Depending on the contaminant of concern, a subset of these activities may be cultivated. In anaerobic metabolism, nitrate, sulfate, carbon dioxide, oxidized metals, or organic compounds may replace oxygen as the electron acceptor.

Anaerobic dechlorination also may occur via cometabolism where the dechlorination is incidental to the metabolic activities of the organisms. In this case, contaminants are degraded by microbial enzymes that are metabolizing other organic substrates. Cometabolic dechlorination does not appear to produce energy for the organism. At pilot- or full-scale treatment, cometabolic and direct dechlorination may be indistinguishable, and both processes may contribute to contaminant removal.

Quoted from US. EPA 2006 Engineering Issue: In Situ and Ex Situ Biodegradation Technologies for Remediation of Contaminated Sites

architecture: "Architecture" refers to the physical distribution of the contaminant in the subsurface. Residuals that take the form of long thin ganglia or small dispersed globules provide a larger surface area that will dissolve much faster than if the same amount of liquid were concentrated in a competent pool.

Sources: For purposes of this discussion, a DNAPL source zone includes the zone that encompasses the entire subsurface volume in which DNAPL is present either at residual saturation or as "pools" of accumulation above confining units. In addition, the DNAPL source zone includes regions that have come into contact with DNAPL that may be storing contaminant mass as a result of diffusion of DNAPL into the soil or rock matrix.

source zone: For purposes of this discussion, a DNAPL source zone includes the zone that encompasses the entire subsurface volume in which DNAPL is present either at residual saturation or as "pools" of accumulation above confining units. In addition, the DNAPL source zone includes regions that have come into contact with DNAPL that may be storing contaminant mass as a result of diffusion of DNAPL into the soil or rock matrix.

focal ulceration: The process or fact of a localized area being eroded away.

metaplasia of the glandular stomach: A change of cells to a form that does not normally occur in the tissue in which it is found.

hyperplasia of the glandular stomach: A condition in which there is an increase in the number of normal cells in a tissue or organ.

histiocytic: Degenerative.

duodenum: First part of the small intestine.

microcytic: Any abnormally small cell.

squamous cell papillomas: A small solid benign tumor with a clear-cut border that projects above the surrounding tissue.

squamous cell carcinomas: Cancer that begins in squamous cells-thin, flat cells that look under the microscope like fish scales. Squamous cells are found in the tissue that forms the surface of the skin, the lining of hollow organs of the body, and the passages of the respiratory and digestive tracts. Squamous cell carcinomas may arise in any of these tissues.

jejunum: The middle portion of the small intestine, between duodenum and ileum. It represents about 2/5 of the remaining portion of the small intestine below duodenum.

ileum: The distal and narrowest portion of the small intestine.

squamous: Flat cells that look like fish scales.

metaplasia: A condition in which there is a change of one adult cell type to another similar adult cell type.

ossification: The process of creating bone, that is of transforming cartilage (or fibrous tissue) into bone.

clastogenesis: Any process resulting in the breakage of chromosomes.

neoplastic: Abnormal and uncontrolled growth of cells.

ulceration: The process or fact of being eroded away.

leucocytosis: An elevation of the total number of white cells in blood.

neutrophils: A type of white blood cell.

chromodulin: A small protein that binds four trivalent chromium ions.

biomagnification: The increased accumulation and concentration of a contaminant at higher levels of the food chain; organisms higher on the food chain will have larger amounts of contaminants than those lower on the food chain, because the contaminants are not eliminated or broken down into other chemicals within the organisms.

exencephaly: Cerebral tissue herniation through a congenital or acquired defect in the skull.

everted viscera: Rotated body organs in the chest cavity.

To Be Considered: Documents, such as federal or state guidances, that are not legally binding but may be relevant to the topic in question.

gaining: A gaining surface water body is one where groundwater flows into it.

losing: A surface water body is losing when there is a permeable sediment bed that is not in contact with the groundwater allowing the surface water to seep through it.

fluvial: Of or pertaining to flow in rivers and streams.

lacustrine: Of or pertaining to a lake as in lacustrine sediments—sediments at the bottom of a lake.

lipid: Any class of fats that are insoluble in water.

lipophilic: Able to dissolve in lipids—in this case fatty tissue.

organelles: A part of a cell such as mitochondrion, vacuole, or chloroplast that plays a specific role in how the cell functions and membranes.

RfD: The RfD is an estimate of a daily exposure of the human population (including sensitive sub-groups) to a substance that is likely to be without "the appreciable risk of deleterious effects during a lifetime." An RfD is expressed in units of mg/kg-day.

autonomic: That part of the nervous system that controls non-conscious actions such as heart rate, perspiration and digestion.

ataxia: Lack of muscle coordination.

funnel-and-gate configuration: A system where low-permeability walls (the funnel) placed in the saturated zone direct contaminated ground-water toward a permeable treatment zone (the gate)

References: ATSDR (Agency for Toxic Substances and Disease Registry). 2015. Draft Toxicological Profile for Perfluoroalkyls. 574 pp.

EFSA (European Food Safety Authority). 2008. Opinion of the scientific panel on contaminants in the food chain on perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) and their salts. EFSA Journal 653:1-131.

Hekster, F.M., R.W.P.M. Laane, and P. de Voogt. 2003. Environmental and toxicity effects of perfluoroalkylated substances. Reviews of Environmental Contamination and Toxicology 179:99-121.

Higgins, C. and R. Luthy. 2006. Sorption of perfluorinated surfactants on sediments. Environmental Science & Technology 40(23):7251-7256.

HSDB (Hazardous Substances Data Bank). 2012 Update. Perfluorooctanoic acid.

Kaiser, M.A., B.S. Larsen, C-P.C. Kao, and R.C. Buck. 2005. Vapor pressures of perfluorooctanoic, -nonanoic, -decanoic, -undecanoic, and -dodecanoic acids. Journal of Chemical and Engineering Data 50(6):1841-1843.

Kauck, E.A. and A.R. Diesslin. 1951. Some properties of perfluorocarboxylic acids. Industrial and Engineering Chemical Research 43(10):2332-2334.

Lewis, R.J., Sr., ed. 2004. Sax's Dangerous Properties of Industrial Materials. 11th ed. Wiley-Interscience, Hoboken, NJ. V3:2860.

Lide, D.R. 2007. CRC Handbook of Chemistry and Physics. 88th ed. CRC Press, Boca Raton, FL. 3-412.

SRC (Syracuse Research Corporation). 2016. PHYSPROP Database. SRC Scientific Databases, Accessed May 2016.

UNEP (United Nations Environmental Program). 2015. Proposal to List Pentadecafluorooctanoic Acid (CAS No: 335-67-1, PFOA, Perfluorooctanoic Acid), Its Salts and PFOA-Related Compounds in Annexes A, B and/or C to the Stockholm Convention on Persistent Organic Pollutants. UNEP/POPS/POPRC.11/5.

USEPA (U.S. Environmental Protection Agency). 2016. Drinking Water Health Advisory for Perfluorooctanoic Acid (PFOA).#pdfsmall# Office of Water, EPA 822-R-16-005, 103 pp

• Overview
• Policy and Guidance
• Conceptual Site Models
• Fate and Transport of Contaminants
• Site Characterization
• Risk Assessment
• Remediation
  • Capping
  • Dredging
  • Excavation
  • Innovative
  • Institutional Controls
  • Monitored Natural Recovery
• Additional Resources

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Innovative

This section contains research and development information on technologies that are generally in the developmental or demonstration phase of their lifecycle.

A Community Guide to Amended Sediment Caps
EPA 542-F-21-002, 2 pp, 2021

Community Guide to In Situ Sediment Amendments
EPA 542-F-21-015, 2 pp, 2021

The Community Guide series (formerly Citizen's Guides) is a set of two-page fact sheets describing cleanup methods used at Superfund and other hazardous waste cleanup sites. Each guide answers six questions about the method: 1) What is it? 2) How does it work? 3) How long will it take? 4) Is it safe? 5) How might it affect me? 6) Why use it?

Approaches For Managing Contaminated Sediments
Michalsen, M. and G. Rosen | SERDP & ESTCP Webinar Series, Webinar #124, December 2020

Two webinars presented as part of the SERDP and ESTCP series focused on DoD-funded research efforts to measure and manage contaminated sediments. The first presentation discussed an approach to develop and validate a standardized polymeric sampler method to quantify freely-dissolved organic contaminant concentrations of PAHs and PCBs in sediment porewater. The second discussed research results following long-term monitoring of AquaGate+PAC™ to reduce PCB availability in surface sediment at Pier 7 of the Puget Sound Naval Shipyard. Additional information on the Puget Sound Naval Shipyard Pier 7 project

Bacterial and Benthic Community Response to Inorganic and Organic Sediment Amendments
Arias-Thode, Y.M., G. Rosen, and J. Leather, SPAWAR.
SERDP Project ER-1551, 59 pp, 2010

This project examined the effects on both the macro and micro biological benthic community after amendment additions of materials for remediation of mixed heavy metal contamination: apatite (an inorganic calcium phosphate amendment), chitin, and acetate, as well as geotextile mats containing apatite and the organoclay bentonite. All amendments were examined singly and in combination for their potential ecological impacts and for their capacity to sequester and immobilize metals. In the suggested concentrations, apatite, chitin, and geotextiles containing apatite and organoclay are considered non-toxic to marine invertebrates in marine sediments.

Cleaning Of Oil-Polluted Bottom Sediments Of The Boreal Lake, Samotlor Oil Field, North Russia: Case Report
Frank, Y.A., D.S. Vorobiev, O.E. Merzlyakov, F.R. Sataev, A.A. Trifonov, E.O. Kopylov, K.V. Stryuk, E.A. Kalinovskaya S.V. Gronskiy, O.V. Chibrikov, V.V. Perminova, Y.V. Branevskiy, S.P. Kulizhskiy, and T.S. Hunter | Water Science & Technology 82(12): 3062-3073(2020)

A flotation-based technology using specially designed airlift plants was tested to remove crude oil from the bottom sediments of a boreal lake. The sediments are dominated by peat and are unevenly polluted. The average total oil concentration was reduced from 111 g/kg to 1.99 g/kg during the 1.5-month field test. Secondary water contamination was minimal; the content of oil hydrocarbons in the water after the project was completed did not exceed 0.09 ± 0.04 mg/L.

The Cooperative Institute for Coastal and Estuarine Environmental Technology

Although the CICEET program at the University of New Hampshire concluded all operations at the end of 2012 owing to loss of funding, details of 170+ projects conducted 1997-2012, many of them focused on sediments, are available in the searchable online Project Explorer database.

Evaluating the Efficacy of Bioaugmentation for In-Situ Treatment of PCB Impacted Sediments
Sowers, K.R., U. Ghosh, and H.D. May.
ESTCP Project ER-201215, 154 pp, 2018

Both anaerobic halorespiring and aerobic PCB-degrading bioamendments were mass cultured, transported to a site, and delivered through a water column to sediments without loss of viability. Treatment with the bioamendment mixture reduced the mean total PCB concentration by an average of 52% and the aqueous PCB fraction by 95% after 13.5 months. The innovative aspect of the technology is the application of activated carbon pellets as a solid substrate for 1) delivery of microorganisms into sediments and 2) sequestration and concentration of hydrophobic PCBs in close proximity to the PCB-transforming bacteria.

In Situ Sediment Treatment Using Activated Carbon: A Demonstrated Sediment Cleanup Technology
Patmont, C.R., U. Ghosh, P. LaRosa, C.A. Menzie, R.G. Luthy, M.S. Greenberg, G. Cornelissen, E. Eek, J. Collins, J. Hull, T. Hjartland, E. Glaza, J. Bleiler, and J. Quadrini.
Integrated Environmental Assessment and Management, Vol 11 No 2,195-207, 2014

This paper reviews general approaches for applying AC amendments as an in situ sediment treatment remedy. As of 2014, pilot- or full-scale field sediment treatment projects using AC were completed or in progress at more than 25 field sites in the United States, Norway, and the Netherlands. Collectively, these field projects (along with numerous lab studies) have demonstrated the efficacy of AC for in situ treatment in a range of contaminated sediment conditions. Results indicate that in situ sequestration and immobilization treatment of hydrophobic organic compounds using either surface application or mixing in can reduce pore water concentrations and bio-uptake significantly, often becoming more effective over time due to progressive mass transfer. Certain conditions, such as use in unstable sediment environments, should be taken into account to maximize AC effectiveness over long time periods. In situ treatment is generally less disruptive and less expensive than traditional sediment cleanup technologies, such as dredging or isolation capping.

Measurement and Modeling of Ecosystem Risk and Recovery for In Situ Treatment of Contaminated Sediments
Luthy, R., Y.-M. Cho, Y. Choi, Y. Wu, and D. Werner.
SERDP Project ER-1552, 2015

The overarching objective of this project was to advance sediment in situ activated carbon (AC) treatment technologies. The work included an investigation of the potential repartitioning of contaminants in sediment following the removal of AC after stabilization treatment, standardization of field monitoring methods using polyethylene passive samplers, and development of a user-friendly, stand-alone program for an HOC mass transfer model to predict sequestration and pore-water concentrations. The SERDP project page hosts reports for phases 1, 2, and 3 of this effort; a desorption model in a zipped file; and a user manual.

NAVFAC Technology Transfer Review: Sediment Reactive Capping
Naval Facilities Engineering Command, 11 pp, 2015

This fact sheet was prepared to provide an overview of reactive capping as an emerging contaminated sediment remediation approach, with attention to capping approaches, materials, deployment, monitoring, and case study examples.

Quantifying Enhanced Microbial Dehalogenation Impacting the Fate and Transport of Organohalide Mixtures in Contaminated Sediments
Haggblom, M., D. Fennell, L. Rodenburg, L. Kerkhof, and K. Sowers.
SERDP Project ER-1492, 221 pp, 2012

The project investigated techniques and amendments to enhance microbial dehalogenation in sediments contaminated with organohalide mixtures and developed methods and tools to monitor the effectiveness of biostimulation processes. Organohalide-contaminated sediments were found to contain diverse communities of dehalogenating microorganisms. Results show that dechlorination of historical PCB and PCDD/F contaminant mixtures can be stimulated by addition of amendments and/or bioaugmentation with dechlorinating bacteria.

Trap & Treat: Patented Reactive Barrier
University of New Hampshire .

A University of New Hampshire research group developed a phosphate-based barrier for sediments deployment. USPTO granted the Barrierite(tm) technology U.S. Patent No. 6,290,637 on September 18, 2001 .

Case Studies

Federal Remediation Technologies Roundtable Cost and Performance Database

This searchable database contains case studies of both innovative and conventional sediment cleanups using in situ and ex situ technologies.

Alternatives Evaluation Report: Penobscot River Phase III Engineering Study, Penobscot River Estuary, Maine
United States District Court, District of Maine, 221 pp, 2018

Beginning in 1967, a chlor-alkali facility located in Orrington, Maine, released mercury into the Penobscot River Estuary. Hg releases at overall declining concentrations continued throughout facility operation and ceased with facility closure in 2000. The slow rate of Hg concentrations decline in the area is attributable, in part, to the presence in the Estuary of a large pool of Hg-affected mobile sediment, which is retained in the Estuary by natural processes that result in the landward flow of both bottom water and associated sediment under the influence of tides. Six remedial alternatives were evaluated in this report: (1) monitored natural recovery; (2) enhanced monitored natural recovery; (3) dredging; (4) thin layer capping in Mendall Marsh; (5) amendment application in Mendall Marsh; and (6) dredging in intertidal and subtidal zones plus thin layer capping in Mendall Marsh. Bench-scale treatability studies were conducted to provide data for the development and evaluation of alternatives. The Phase III Engineering Study recommended a suite of remedies—thin layer capping, dredging, and long-term monitoring—to address various portions of the River. For additional information, including appendices to this report: Penobscot Study Website

The Ashumet Pond Reactive Barrier
Massachusetts Military Reservation, Cape Cod.

• 2009 Ashumet Pond Update
• Phosphorus Plume Remediation

A geochemical barrier was applied in the groundwater discharge zone of a kettle-hole pond to address the well-defined discharge of a dissolved phosphorus plume. In August 2004, ZVI was mixed into near-shore pond-bottom sediment (3% by weight) to a depth of about 0.6 m, extending 12.2 m offshore along 91.4 m of shoreline in the area of highest observed pond-bottom phosphorus. The sediment mixture was created by excavating the pond-bottom material while the pond was locally dewatered using a cofferdam and large pumps. An excavator mixing bucket blended the pond-bottom sediment and iron filings prior to placement of the mixture on the pond bottom. The ZVI barrier is ~300 ft long, 40 ft wide, and 3 ft thick. Excavation of the dewatered pond bottom provided a unique opportunity to install instrumentation for barrier performance monitoring. Monitoring the performance of a remediation system at this interface required adapting sampling strategies similar to those used in groundwater/surface-water interaction studies. Additional information: McCobb et al. 2009a, McCobb et al. 2009b

Case Study: Sediment Remediation, Bangor Landing, Bangor, Maine
Howatt, K.
Remediation of Contaminated Sediments Workshop, 29-30 April 2010, Westford, MA. Northeast Waste Management Officials' Association. 14 slides, 2010

RMT, Inc., the Bangor project consultant, completed a remediation project in August 2010 to dredge and cap about 1.5 acres of riverbed heavily contaminated with MGP tar. RMT's NAPL Trapping Cap (patent pending) is designed to control tar migration from sediment permanently and predictably by redirecting migrating tar to a controlled accumulation area, where the tar NAPL is trapped and the gas is vented to the atmosphere. The first full-scale application of the NAPL Trapping Cap was installed at the Bangor Landing site. The cap is constructed of a clay layer, a layer that is impermeable to liquids but allows gases through, and a stone layer that resembles the shoreline. U.S. Patent Application 20090110486, dated April 30, 2009, has been filed for the NAPL Trapping Cap. A brief article about this cleanup is available in the April 2010 issue of Civil Engineering. Although MGP tar is a DNAPL, tar globs at this site have been observed to float on the river's surface. The phenomenon is explained in a paper by E.L. McLinn and T.R. Stolzenburg, "Ebullition-Facilitated Transport of Manufactured Gas Plant Tar from Contaminated Sediment," Environmental Toxicology and Chemistry 28(11):2298-2306(2009)

Demonstration of In Situ Treatment with Reactive Amendments for Contaminated Sediments in Active DoD Harbors
Kirtay, V., G. Rosen, M. Colvin, J. Guerrero, L. Hsu, E. Arias, R.K. Johnston, B. Chadwick, et al.
ESTCP Project ER-201131, 884 pp, 2017

In situ remediation of PCB-contaminated surface sediment was demonstrated by placing a reactive amendment (powdered activated carbon, or PAC) at a site located at the Puget Sound Naval Shipyard & Intermediate Maintenance Facility, Bremerton, Wash. The PAC was placed successfully on the seafloor of a half-acre target site to sorb PCBs in sediments, thereby reducing bioavailability and limiting bioaccumulation of contaminants into the tissues of benthic invertebrates. The sorbent material, AquaGate+PAC, was manufactured by coating an aggregate core with PAC held in a bentonite clay binder. The AquaGate, which is denser than water, sinks rapidly through the water column directly to the surface of the sediment. Over a short period of time (days), the PAC coating of the AquaGate releases from the aggregate, and bioturbation incorporates the PAC into the surface sediments over time. This project demonstrated the placement and quantitative integration of a suite of common and novel monitoring tools to evaluate amendment stability and performance in deep water (15 m) at an active Naval shipyard with high vessel traffic.

Demonstration Testing and Full-Scale Operation of the Biogenesis^SM Sediment Decontamination Process: Keasbey, New Jersey
BioGenesis Washing BGW, LLC, Springfield, VA. 1,019 pp, 2009

A full-scale demonstration of the BioGenesis^SM Sediment Decontamination Technology was performed on 15,000 cubic yards of dredged material for the New Jersey Department of Transportation, Office of Maritime Resources. The technology is a patented, low-temperature decontamination process for fine-grained sediment that uses impact forces and proprietary washing chemicals to remove organic and inorganic contamination. The resulting material can be used to create high-end topsoil or other construction products. Full-scale cost projections were $51.00 to $59.00 per cubic yard.

Design of a Reactive Cap Remedy for Soft, NAPL-Impacted Sediments
Carroll, S. and W. Haswell.
Abstracts: Manufactured Gas Plant Conference 2015.

A reactive cap was designed to address very soft sediments in the Grand Calumet River in Hammond, Indiana, that contain coal tar NAPL and elevated PAH and BTEX constituents. The design proposed two different cap sections for different reaches of the river: organoclay to address NAPL migration and dissolved-phase flux of PAHs, and bulk granular activated carbon to address dissolved-phase BTEX contaminants. The design was completed in 2014, and remedial construction is planned for winter 2015. The design process was a weight-of-evidence approach, incorporating a wide array of inputs, such as hydraulic gradients; groundwater to surface water flux measurements; sorbed-phase sediment and dissolved-phase pore water contaminant concentrations; NAPL saturation measurements; and gas ebullition rates as a result of microbial decay, including field and lab measurements of gas generation rates to quantify potential upward gas-driven NAPL flux. Several innovative technologies and methods were used to characterize conditions in the sediments, including laser-induced fluorescence Darts® (Dakota Technologies Inc.) to measure NAPL content in sediments, sorbent samplers to measure contaminant concentrations in pore water, and an instrumented pilot-scale test cap, installed in a wooden cell constructed in the river in 2012 and monitored for a year to obtain predesign data. The collection of similar types of data using different methods (e.g., quantification of contaminant concentrations in pore water by conventional pore water sampling and analysis; pore water extraction from sediment cores coupled with solid-phase microextraction analysis; and AGI sorbent samplers) has allowed comparison of results obtained by the various methods. Additional Resources:

• Grand Calumet River Legacy Act Cleanup.
  U.S. EPA, Great Lakes National Program Office.
• Gallery of Grand Calumet Cleanup Photos.
  Indiana Dept. of Environmental Management
• Sediment Remediation Research on In Situ Treatment: East Branch Grand Calumet River.
  U.S. EPA, Great Lakes National Program Office, 3 pp, 2014
• GLSR Approaching End of Grand Calumet River Remediation Project.
  Powers, J. et al. International Dredging Review, Sep/Oct 2014

Electrochemical Remediation Technologies (ECRTS): In Situ Remediation of Contaminated Marine Sediments. Innovative Technology Evaluation Report
EPA 540-R-04-507, 74 pp, 2007

In the demonstration, a DC/AC current was passed between an electrode pair (anode and cathode) in sediment to mineralize organic contaminants (PAHs, phenols) through an electrochemical geooxidation process or to complex, mobilize, and remove metal contaminants (mercury) deposited at the electrodes through induced complexation. The system did not perform as well as anticipated, due in part to system operational problems, resulting in an early shutdown of the system.

Evaluating the Efficacy of a Low-Impact Delivery System for In situ Treatment of Sediments Contaminated with Methylmercury and Other Hydrophobic Chemicals
Menzie, C., B. Amos, S.K. Driscoll, U. Ghosh, and C. Gilmour.
ESTCP Project ER-200835, 122 pp, 2016

Field demonstrations of in situ treatment of PCBs and mercury with activated carbon (AC) delivered using the SediMite(r) delivery system were conducted at two sites within Canal Creek at Aberdeen Proving Ground in Edgewood, Maryland. The application of SediMite to a third site--Bailey Creek at Fort Eustis in Virginia--is described for comparison along with data for a fourth site where SediMite was used to treat PCBs within a Phragmites (reed) marsh. PCBs bioavailability typically declined by >80% across these sites, with values >90% achievable. Efficacy was related to the presence of target doses of AC. Results were equivocal for treatment of mercury. Effects of treatment on native biota were judged to be negligible. Additional information: ESTCP Cost & Performance Report

FY02 Final Report on Phytoremediation of Chlorinated Ethenes in Southern Sector Seepline Sediments of the Savannah River Site
R.L. Brigmon, F.M. Saunders, D. Altman, E. Wilde, C.J. Berry, M. Franck, P. McKinsey, S. Burdick, F. Loeffler, S. Harris. WSRC-TR-2002-00557, 171 pp., 2003.

This final report details the operations and results of a 3-year phytoremediation project involving plantings of loblolly pines, hybrid poplars, sterile Vetiver grass, and a wetland system to remediate TCE-contaminated sediment.

Field Testing of Activated Carbon Mixing and In Situ Stabilization of PCBs in Sediment
ESTCP Project ER-0510, 288 pp, 2009

A field-scale project was conducted to demonstrate that activated carbon (AC) sorbent mixed with sediment is a cost-effective, nonremoval, in situ management strategy for reducing risk and the bioavailability of PCBs in offshore sediments at the Hunters Point Shipyard site. The demonstration also compared the effectiveness, in terms of AC application and ease of use, of two available large-scale mixing technologies. Uptake studies showed 50 to 66% reductions in PCB uptakes in AC-amended areas, depending on AC dose. Field-exposed AC retained a strong stabilization capability to reduce aqueous equilibrium PCB concentrations by as much as 95%, depending on AC dose, effective up to at least 18 months. See also the ESTCP Cost and Performance Report.

Innovative In-Situ Remediation of Contaminated Sediments for Simultaneous Control of Contamination and Erosion
Knox, A.S., D.D. Reible, M.H. Paller, and I.G. Petrisor.
WSRC-RP-2007-00666, 103 pp, 2007

This report describes an investigation of the use of combinations of sequestering agents to develop in situ active sediment caps that stabilize mixtures of contaminants and act as a barrier to mechanical disturbance under a broad range of environmental conditions. The investigators determined the most effective active cap materials, cap composition, and the effects of active components on metal bioavilability, retention, and toxicity.

In-Situ Solidification of Contaminated Sediments: A Technology Demonstration Project
Electric Power Research Institute (EPRI), Palo Alto, CA. Project 3002005216, 1086 pp, 2014

As an alternative to dredging and capping sediments affected by historical MGP operations, a pilot demonstration was performed to determine if in situ solidification (ISS) and support equipment contained on a barge could solidify tar-contaminated sediments through a column of water using readily available grout components while meeting U.S. EPA performance goals. Project elements included the control of turbidity, pH, and sheen using a dual-turbidity curtain system, and results showed that rigid controls such as steel sheet piling may not be required for good performance. The report covers the site characterization and treatability study of the pilot area; permitting and mobilization; ISS operations in December 2013; sampling and testing; monitoring; and pilot and estimated full-scale costs. The primary result of the project was proof of concept that ISS of submerged sediments is achievable and is ready to be tested at a larger scale. Additional information: Connecticut River ISS update by Jansen et al. in Remediation Journal 26(2):25-49(2016)

In Situ Treatment at PCB Contaminated Sediment Sites
Blackman, T., M. Martin, G. Braun, S. Ozkan, and E. Ashley.
Lockheed Martin Middle River Complex Feasibility Study Team, Project Note 2, 92 pp, 2013

Research and pilot studies on the in situ treatment of sediments by activated carbon application and its effectiveness for PCBs, PAHs, and metals stabilization indicate that in situ AC treatment is 75-95% effective for reducing PCBs and PAHs bioavailability. To provide background for future sediment remediation at the Middle River Complex site, located in Maryland , this project note presents a general description of in situ treatments, a brief review of ongoing research, and descriptions of projects and pilot studies where in situ treatments have been applied.

In Situ Wetland Restoration Demonstration: ESTCP Cost and Performance Report
Ruiz, N., J. Bleiler, K. Gardner, M. Johnson, T. Estes, D. Anders, and D. Barclift.
ESTCP Project ER-200825, 55 pp, 2014

The field demonstration was performed at Aberdeen Proving Ground, MD, to evaluate the ability of activated carbon (AC) to reduce PCB bioavailability and associated risks in Canal Creek wetland habitats using a variety of AC delivery systems: Powder-activated carbon slurry and two pelletized AC products, AquaBlok^® and SediMite^™. An engineered manufactured soil cover system provided the control. Each sequestration agent was mechanically deployed over the surface of a wetland and allowed to integrate into the surface layer of the hydric soil through natural mixing processes. The goal of this approach was risk reduction, not mass removal; however, while the findings of the overall program suggest that AC addition can sequester PCBs, the field demonstration findings were not conclusive in demonstrating effective reductions in bioavailability. Additional information: Project Summary Presentation

Mass Balance, Beneficial Use Products, and Cost Comparisons of Four Sediment Treatment Technologies near Commercialization
Estes, T.J., V.S. Magar, D.E. Averett, N.E. Soler, T.E. Myers, E.J. Glisch, and D.A. Acevedo.
ERDC/EL TR-11-1, 286 pp, 2011

This report covers the technical status of 4 sediment treatment technologies: JCI/Upcycle rotary kiln thermal treatment/light-weight aggregate (LWA); Cement-Lock® technology/cement; Minergy® glass furnace technology/glass aggregate; and BioGenesis^SM sediment washing process/manufactured soil. The report describes the process efficiency in terms of mass balance, gives pre- and post-treatment processing requirements, and estimates full-scale implementation costs at a scale compatible with a dredging operation.

Predicting and Validating the Field Performance of Novel Sorbent-Amended Sediment Caps
Lowry, G.V., J.L. Fairey, D.A. Dzombak, and J.M. VanBriesen.
Cooperative Institute for Coastal and Estuarine Environmental Technology, 36 pp, 2009

This paper contains an evaluation of the performance of thin-layer (1.25 cm) activated carbon (AC)-amended sand sediment caps as a tool for in situ remediation of PCB-contaminated sediments. The investigators developed the fundamental understanding of the physicochemical processes affecting the transport of PCBs through the AC layer and measured isotherms parameters for nine PCBs onto AC under sediment conditions. Addition of a thin layer of AC to a sand cap significantly improves the ability of the cap to retard transport of PCBs from the underlying sediment to the overlying benthic community and water column. The AC layer is added to the sediment cap using a reactive core mat, consisting of a geotextile filled with AC. These mats are commercially available from companies identified in the report.

Reactive Capping Mat Development and Evaluation for Sequestering Contaminants in Sediment
Hawkins, A.L., G.A. Tracey, J.J. Swanko, K.H. Gardner, and J.S. Melton.
TR-2366-ENV, SERDP Project ER-1493, 163 pp, 2011

In April 2008, a prototype reactive geotextile mat system was deployed in Cottonwood Bay in Grand Prairie, Texas, in four 25 ft x 25 ft test arrangements (bare single-layer geotextile, single-layer geotextile with sand cap, bare double-layer geotextile, sand cap only) and an undisturbed control. Results indicated that the selected implementation method, including mat with sand cover, is recommended as an effective technology to sequester contaminants in sediments while preventing uplift due to gas accumulation. Additional information: Appendices

River Raisin Area of Concern: NAPL Area Remediation
Roberts, M., A. Corbin, P. Doody, T. Peters, and C. Robinson. Proceedings of the Western Dredging Association (WEDA) Dredging Summit & Expo '17, Vancouver, British Columbia, Canada, June 26-29, 2017. Paper : p 447-461 + 23 slides , 2017

In April 2008, a prototype reactive geotextile mat system was deployed in Cottonwood Bay in Grand Prairie, Texas, in four 25 ft x 25 ft test arrangements (bare single-layer geotextile, single-layer geotextile with sand cap, bare double-layer geotextile, sand cap only) and an undisturbed control. Results indicated that the selected implementation method, including mat with sand cover, is recommended as an effective technology to sequester contaminants in sediments while preventing uplift due to gas accumulation. Additional information: Appendices

Sediment Management Methods to Reduce Dredging, Part 2: Sediment Collector Technology
Thomas, R.C., J. McArthur, D. Braatz, and T.L. Welp.
ERDC TN-DOER-T13, 11 pp, 2017

This technical note presents an evaluation of sediment collector technology, a new device that may help to manage sediments and reduce traditional dredging requirements. The installation of sediment collector technology in Fountain Creek, Pueblo, Colorado, demonstrated that the technology worked with coarse sediments in a shallow unidirectional flow environment; had minimal maintenance costs over a 1-yr deployment; survived record floods with minimal damage; was capable of producing up to 100 yd³ per hour with a single 30-ft collector; and was relatively inexpensive and easy to deploy without specialized equipment. U.S. EPA funded the demonstration project. Additional information: 12 slides

Sediment Remediation Through Activated Carbon Amendment: Long-Term Monitoring of a Field Pilot in Trondheim Harbour
Cornelissen, G., J. Gunnarsson, G. Samuelsson, and U. Ghosh.
Norwegian Research Council, Project 185032, NGI report no. 20081057-1, 20 pp, 2011

Activated carbon (AC) amendment was applied as a novel remediation technique in a pilot project in Trondheim Harbour in 2008. The project consisted of thin-layer in situ capping with AC implemented using three different methods: AC only, AC covered by a thin layer of sand, and AC mixed with clay. This report describes the establishment of the novel pilot testing fields and their long-term follow-up and monitoring.

Strategic Selection of an Optimal Sorbent Mixture for In-Situ Remediation of Heavy Metal Contaminated Sediments: Framework and Case Study
Chiang, Y.W., R.M. Santos, K. Ghyselbrecht, V. Cappuyns, J.A. Martens, R. Swennen, T. Van Gerven, and B. Meesschaert.
Journal of Environmental Management 105:1-11(2012)

This paper outlines a strategic framework designed to address the development of an in situ sediment remediation solution systematically through assessment, feasibility, and performance studies. The decision-making tools and the experimental procedures needed to identify optimum sorbent mixtures are detailed, with emphasis on the utilization and combination of commercially available and waste-derived sorbents. An application of the proposed framework is illustrated in a case study of a contaminated sediment site in Northern Belgium with high levels of As, Cd, Pb, and Zn originating from historical non-ferrous smelting. Longer abstract

Use of Amendments for In Situ Remediation at Superfund Sediment Sites
U.S. EPA, Office of Superfund Remediation and Technology Innovation.
OSWER Directive 9200.2-128FS, 61 pp, 2013

This document introduces the most promising amendments for in situ remediation of sediments and summarizes information from three case studies of sites where activated carbon, organoclay, phosphates, bauxite, and/or ZVI have been employed for sediments contaminated with PCBs or PAHs.

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