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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Remedial actions at contaminated sediment sites generally fall within four broad categories: monitored natural recovery, in situ capping, and removal by dredging or excavation. Specific discussions appear below.

Contaminated Sediment Remediation Guidance for Hazardous Waste Sites
USEPA, Office of Solid Waste and Emergency Response, EPA-540/R-05/012, 236 pp, 2005

Contaminated Sediments at Navy Facilities: Cleanup Alternatives
NAVFAC, TDS-2092-ENV, 6 pp, 2002

This document contains a brief description of advantages and disadvantages of monitored natural recovery, in situ capping, dredging, and in situ treatment.

Ex Situ Remediation of Sediment From Serbia Using a Combination of Electrokinetic and Stabilization/Solidification with Accelerated Carbonation Treatments
Popov, N., S. Roncevic, N. Dudukovic, D. Krcmar, Z. Mihaljev, M.Z. Balos, and S. Dordievski.
Environmental Science and Pollution Research [Published 22 November 2020 prior to print]

Three ex situ remediation technologies were applied to Begej River sediments. Conventional electrokinetic treatment (EK) was implemented first to reduce the amount of contaminated sediment and enhance metals accumulation, followed by stabilization/solidification (S/S) to immobilize the accumulated metals. Two types of bio as immobilizing agents were used. Following treatments, sequential extraction procedure (SEP) and TCLP and DIN 3841-4 S4 leaching tests were used to assess risk. EK treatment reduced the amount of polluted sediment by half. TCLP and SEP performed on S/S mixtures after a 28-day maturation period indicated that accelerated carbonation decreased the mobility of critical metals. Moreover, based on the leaching tests, all prepared mixtures were categorized as non-hazardous and safe for disposal according to the relevant Serbian regulations.

Framework for Long-Term Monitoring of Hazardous Substances at Sediment Sites
ASTSWMO Sediments Focus Group, 58 pp, 2009

This paper discusses methods and resources for long-term monitoring of physical, chemical, and biological attributes at contaminated sediment sites and provides examples of appropriate methods for monitoring the effectiveness of capping, dredging, confined disposal, enhanced natural recovery, in situ treatment, monitored natural attenuation, institutional controls, and no action.

Management of Mercury Pollution in Sediments: Research, Observations, and Lessons Learned (DRAFT)
U.S. EPA, National Risk Management Research Laboratory. 87 pp, 2006

This report discusses the most common methods used for remediating contaminated sediments in relation to the chemistry of mercury and its effect on the sorption of mercury on sediment. Three detailed case studies are presented: remediation efforts at Lavaca Bay, TX; management of mercury in Onandoga Lake in Syracuse, NY; and remediation and monitoring of mercury-contaminated sediments in Lake Turingen, Sweden.

Puget Sound Sediment Cleanup Remedy Effectiveness Retrospective
Patmont, C. and R. Healy.
Integrated Environmental Assessment and Management [published online 31 January 2024 before print] [Abstract]

Five completed Puget Sound sediment remediation case studies (Bellingham Bay, St. Paul Waterway, Eagle Harbor, Hylebos Waterway, and Sinclair Inlet) that employed particularly robust remedy effectiveness monitoring programs spanning decades, are reviewed, revealing common lessons for improving remediation outcomes. 1) Though sediment remediation can play an important role in reducing contaminant exposure in areas with higher sediment concentrations, sediment links with fish tissue concentrations diminish at lower levels. As water column exposure from diverse sources becomes predominant, remediating sediments with lower concentrations yields proportionately less risk reduction. 2) Timely monitoring of effective source controls achieving substantial (i.e., >80%) contaminant source load reductions and large-scale capping projects have revealed rapid changes in Puget Sound surface sediment concentrations and biological recovery metrics with an average recovery half-time of 1.6 ± 0.8 years. The weight of evidence suggests that natural recovery of Puget Sound surface sediments is significantly accelerated by exchange across the sediment-water interface from benthic organism feeding behaviors, porewater flux, and tide-generated currents. As a result, effective source controls in Puget Sound have rapidly improved surface sediment quality and achieved more significant risk reductions than broadscale sediment remediation. Moving forward, comprehensive source control efforts that incorporate robust monitoring in an adaptive management framework are the best way to achieve protective remediation objectives.

Remediation of DDT and Its Metabolites in Contaminated Sediment
Chattopadhyay, S. and D. Chattopadhyay.
Current Pollution Reports 1(4):248-264(2015)

Sediment characteristics, positioning, and overlying water column must be considered relevant to the release and transport of DDT and its degradation products (DDTR) when evaluating appropriate remediation options. DDTR and other co-contaminants are not necessarily fixed permanently in the sediments. Changes in geochemical and physical parameters can mobilize these species. DDTR can be transformed or partially degraded in sediments under appropriate environmental conditions; however, the degradation products often are as toxic and persistent as the original pesticides or chlorinated organics. The authors review five remediation technologies applied to remediate DDT-contaminated sediments: dredging, sediment washing, phytoremediation, in situ capping, and monitored natural recovery.

A Review of the In-Situ Capping Amendments and Modeling Approaches for the Remediation of Contaminated Marine Sediments
Labianca, C., S. De Gisi, F. Todaro, M. Notarnicola, and I. Bortone.
Science of The Total Environment 806(Part 3):151257(2022)

The reliability, applicability, and long-term effectiveness of in situ capping (ISC) were investigated, while also comparing reactive and physical ISCs. Activated carbon and organoclay were the most studied amendments for organically-contaminated sediment. In contrast, biochar, clay minerals, and industrial-by products were more often employed in sediments contaminated by metal(loids). There is no better ISC system in absolute terms since technological performance depends on many factors, and only a few experimental investigations included a long-term modeling phase to predict ISC long-term efficiency. The main numerical simulations applied to ISC technology were examined, and most models included simplified transport equations based on diffusion and adsorption. New research directions such as the need for long-term applications on field-scale and cap effectiveness in the presence of site-specific tidal forces and currents are discussed.

Remediation of PAH-Contaminated Soils and Sediments: A Literature Review
Wick, A.F., N.W. Haus, B.F. Sukkariyah, K.C. Haering, and W.L. Daniels.
Virginia Tech, CSES Department, Internal Research Document, 102 pp, 2011

The focus of this report is the degradation of PAHs in dredged sediments placed in an upland setting, where anaerobic conditions exist during initial dewatering and shift to aerobic conditions during soil formation. The literature review provides information on PAH chemistry relevant to its behavior and concentration ranges in different environments; bioavailability; transfer, degradation, and sequestration in sediment and soil; biological remediation techniques; chemical remediation techniques; sampling and analytical methods; and regulations pertaining to dredged material containing PAHs.

Sediment Remedy Effectiveness and Recontamination: Selected Case Studies
ASTSWMO Sediment Focus Group, 85 pp, 2013

This report discusses causes and issues related to recontamination to assist state regulators in the planning and decision-making processes necessary to minimize the potential for recontamination at sediment cleanup sites.

Sustainable Sediment Remediation
Bullard , A., R. Wensink, and S. Moore.
TR-NAVFAC EXWC-EV-1515, 55 pp, 2015

Most green and sustainable remediation (GSR) evaluations to date have been focused on terrestrial sites with soil or groundwater contamination issues. In providing a connection between guidance specific to sediment sites and existing Navy optimization/GSR guidance, this paper introduces a new version of the SiteWise™ program that has been developed to integrate sediment-specific remedial activities.

Survey of Sediment Remediation Technologies
Reis, Edson, Andrea Lodolo, Stanislav Miertus
International Centre for Science and High Technology, 124 pp, 2007

This document is a broad review of conventional and innovative technologies for remediation of sediments. It covers both in situ and ex situ treatments.

Sustainable Ex-Situ Remediation of Contaminated Sediment: A Review
Zhang, Y., C. Labianca, L. Chen, S. De Gisi, M. Notarnicola, B. Guo, J. Sun, S. Ding, and L. Wang. | Environmental Pollution 287:117333(2021)

This paper critically reviews the state-of-art ex situ treatment technologies and resource utilization methods for contaminated sediment. Applying different techniques can successfully transform sediment into sustainable construction materials, such as ceramsite, supplementary cementitious materials, fill materials, paving blocks, partition blocks, ready-mixed concrete, and foamed concrete. Proper remediation technologies should be selected and designed according to the physical and chemical characteristics of sediment, without neglecting important aspects, such as cost, safety, environmental impacts, readiness level of the technology, and social acceptability. Combining different assessment methods (e.g., environmental impact assessment, cost-benefit analysis, multi-criteria decision analysis, and life cycle assessment) should be employed to comprehensively evaluate the feasibility of different sustainable remediation technologies. Longer abstract

Sediment Assessment and Monitoring Sheets (SAMS)

Guidelines for Using Passive Samplers to Monitor Organic Contaminants at Superfund Sediment Sites
Burgess, R.
U.S. EPA, OSRTI, OSWER Directive 9200.1-110FS, SAMS #3, 32 pp, 2012

This SAMS discusses passive samplers that can be used in water column and sediment deployments, in some cases simultaneously. When deployed together, passive samplers placed in the water column and in sediment can provide information about hydrophobic organic contaminant gradients between sediment and water. This SAMS does not provide specific protocols on deployment and recovery, nor does it describe the chemical analysis procedures for passive samplers.

A Primer for Remedial Project Managers on Water Quality Standards and the Regulation of Combined Sewage Overflows under the Clean Water Act
U.S. EPA, Office of Superfund Remediation and Technology Innovation. Sediment Assessment and Monitoring Sheet (SAMS) #4, OSWER Directive 9200.1-116-FS, 23 pp, 2013

This fact sheet summarizes for RPMs how combined sewage overflows and other discharges are regulated under the Clean Water Act (CWA). It emphasizes the objectives of the legislation, how it is often applied in practice, and some significant challenges in employing those controls to meet the objectives of the CWA. Similarities and differences between the CWA and CERCLA objectives and how they can affect remediation of contaminated sediment are also highlighted.

Using Fish Tissue Data to Monitor Remedy Effectiveness
U.S. EPA, OSRTI, OSWER Directive 9200.1-77D, SAMS #1, 14 pp, 2008

Many factors can influence the measured concentrations of contaminants in biota tissues. This document provides technical guidance to U.S. EPA staff on developing monitoring plans for contaminated sediment sites. It also provides information to the public and to the regulated community on how EPA intends to exercise its discretion in implementing monitoring plans.

Understanding the Use of Models in Predicting the Effectiveness of Proposed Remedial Actions at Superfund Sediment Sites
U.S. EPA, OSRTI, OSWER Directive 9200.1-96FS, SAMS #2, 36 pp, 2009

This product is a primer for those not experienced in the development and use of models at sediment sites. It explains the typical objectives of modeling, how models are built, how they are used to predict the effectiveness of remedies, and how the uncertainty in model predictions can be addressed.

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