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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Dredging

Environmental dredging removes contaminated sediment from a water body without draining or diverting the water. Dredges remove a certain amount of water with the sediment. The sediments are usually dewatered on land, and the water is usually treated before discharge back to the water body or public treatment works. The contaminated sediment is then disposed of in a landfill or a confined disposal facility. Highly contaminated sediment may be treated, most often by stabilization, before disposal. Unlike navigational dredging, which stresses the quick removal of relatively clean sediment, environmental dredging is more precise with greater emphasis on controlling the resuspension of contaminated sediment. Environmental dredging can be accomplished using either mechanical or hydraulic devices. In the former a bucket is used to collect the sediment and deposit it in a hopper or other container. In the later the sediment is loosened with some form of cutter head and sucked into a holding tank. Mechanically dredged sediments contain about the same water content as the in place sediment. Hydraulically dredged sediments, on the other hand, are more like a thin slurry containing 10 to 20 percent solids.

For both mechanical and hydraulic dredging, a dewatering step is necessary to reduce the volume of material that needs to be taken to a treatment or disposal site. The water that is removed from the sediment generally requires treatment before it is returned to the surface water body. Because hydraulic dredging operates on the principle of transporting the contaminated sediment to the shore as a slurry, it produces a much larger volume of water requiring treatment. For quality control and safety, the water outside the working area is monitored and analyzed to ensure that contaminated sediment is not escaping.

To protect against resuspension during dredging, the contaminated sediment area can be enclosed with silt curtains that extend to the bottom. These curtains have floatation devices at the surface and anchors at the bottom to ensure they hug the sediment floor. They are best deployed in low current environments. Real time monitoring for increased turbidity is used as an early warning sign that sediment may be resuspending.

Text adapted directly from USEPA. 2004. Presenter's Manual for: Remediation of Contaminated Sediments. Office of Solid Waste and Emergency Response, 58 pp.

Dredging and Dredged Material Management: Engineering and Design
U.S. Army Corps of Engineers. EM 1110-2-5025, 920 pp, 2015

This Engineer Manual presents a comprehensive summary of dredging equipment and dredged material placement techniques with considerations for the selection and use of various types of dredging equipment and techniques for placement. Information includes (1) short-and long-term fates of dredged material in the open-water environment and methods for quantifying each type of material; (2) contaminant pathways from open-water placement; (3) management and control methods for open-water placement; and (4) considerations for open-water site operation, monitoring, and management. Detailed guidance is given for diked placement of dredged material in confined disposal facilities. Chapter 5 outlines opportunities for beneficial use of dredged material and provides many case studies.

Dredging in Sediments Containing Munitions and Explosives of Concern (MEC)
Welp, T., G. Follett, M. Crull, and C.E. Pollock.
ERDC/CHL TR-08-12, 241 pp, 2008

The document compiles information gained from experiences on past dredging projects involving MEC, describing the different types of dredges and dredging projects that can encounter MEC, how these dredges' operational methodologies can be affected by MEC, and methodology modifications that have been used to deal with MEC. The text addresses engineering controls to mitigate detonation hazards, underwater MEC detection and discrimination technologies, contracting, public awareness, safety requirements, and MEC separation techniques and (where available) subsequent impacts on production rates and costs.

Evaluating the Effectiveness of Contaminated-Sediment Dredging
Gustavson, K. et al
ES&T Volume 42, Issue 14, pp. 5034-5378

The Four Rs of Environmental Dredging: Resuspension, Release, Residual, and Risk
Bridges, T.S., S. Ells, D. Hayes, D. Mount, S.C. Nadeau, M.R. Palermo, C. Patmont, and P. Schroeder.
ERDC/EL TR-08-4, 63 pp, 2008

This report summarizes the results of a workshop sponsored by the Army Corps of Engineers and U.S. EPA in April 2006 and attended by 50 experts from government, the private sector, and academia.

Mechanical Dewatering of Navigation Sediments: Equipment, Bench-Scale Testing, and Fact Sheets
U.S. Army Corps of Engineers, ERDC TN-DOER-T7, 34 pp, 2004

A Parametric Model for Estimating Costs for Remediating Contaminated Sediment Sites Using a Dredging Method: A Budgetary & Planning Tool for Decision-Makers
Rosengard, J., J. Wallace, M. Otten, A. MacDonald, and R. Lafrenz. International Journal of Soil, Sediment and Water 3(2):#9(2010)

This paper presents a viable parametric model for assisting managers and decision-makers in developing appropriate cost estimates for the processing and disposal of dredged materials. The model can be used for planning and budgetary purposes, communicating with stakeholders, and providing guidance to senior management. This multi-variable financial model enables cost estimates for either a single site or for a portfolio of sites (while still allowing for individual site specifications) by providing cumulative costs over the overall remediation time horizon. It allows for "what if" scenarios and provides both numerical and graphical depictions of the estimates.

Review of Phytoreclamation and Management Approaches for Dredged Material Contaminated with Lead
U.S. Army Corps of Engineers, ERDC TN-DOER-C29, 11 pp, 2003

A Review of Risk-Based Approaches to the Development of Screening Criteria for Soils and Application to Beneficial Use of Dredged Material
Bailey, S.E., D.E. Averett, and P.R. Schroeder.
ERDC TN-DOER-D14, 30 pp, 2012

This technical note discusses considerations for applying criteria to beneficial use of dredged material and summarizes approaches that have been used within and outside the United States to develop risk-based screening criteria for soils. These soil criteria potentially could be used or adapted to develop screening criteria for beneficial use of dredged sediments.

Sediment Dredging at Superfund Megasites: Assessing the Effectiveness
Committee on Sediment Dredging at Superfund Megasites, National Research Council, 316 pp, 2007

Technical Guidelines for Environmental Dredging of Contaminated Sediments
Palermo, M.R., P.R. Schroeder, T.J. Estes, and N.R. Francingues.
ERDC/EL TR-08-29, 302 pp, 2008

This document supports the Contaminated Sediment Remediation Guidance for Hazardous Waste Sites (USEPA 2005) by providing detailed information regarding evaluation of environmental dredging as a remedy component. It covers initial evaluation, pertinent site conditions and sediment characteristics, environmental dredging performance standards, equipment capabilities and selection, evaluation of production, duration, and transport, methods for estimating resuspension, residuals and release, control measures, operating methods and strategies, and monitoring.

Technical & Operational Guidance Series: In-Water and Riparian Management of Sediment and Dredged Material
New York Depart of Conservation, TOGS 5.1.9, 77 pp, 2004

Confined Disposal Facilities

Design Guidance for Confined Disposal Facility Lateral Seepage Control
U.S. Army Corps of Engineers, ERDC TN-DOER-R7, 12 pp, 2005

Effects of Confined Disposal Facility and Vadose Zone Characteristics on Leachate Quality
U.S. Army Corps of Engineers, ERDC TN-DOER-C31, 15 pp, 2003

Evaluation of Chemical Clarification Polymers and Methods for Removal of Dissolved Metals from CDF Effluent
Bailey, Susan E., Sangchul Hwang, Michael C. Brooks, and Paul R. Schroeder
U.S. Army Corps of Engineers, ERDC TN-DOER-R10, 16 pp, 2006

Evaluation of Dredged Material Proposed for Disposal at Island, Nearshore, or Upland Confined Disposal Facilities — Testing Manual
U.S. Army Corps of Engineers, ERDC/EL TR-03-1, 337 pp, 2003

Liner Design Guidance for Confined Disposal Facility Leachate Control
U.S. Army Corps of Engineers, 25 pp, 2004

Screening Evaluations for Upland Confined Disposal Facility Effluent Quality
Schroeder, Paul, Trudy Estes, and Susan Bailey
U.S. Army Corps of Engineers, ERDC TN-DOER-R11, 12 pp, 2006

Geotechnical Properties

Geotechnical Design Considerations for Contained Aquatic Disposal
U.S. Army Corps of Engineers, ERDC TN-DOER-N5, 19 pp, 2000

Geotechnical Properties and Sediment Characterization for Dredged Material Models
U.S. Army Corps of Engineers, ERDC TN-DOER-N13, 14 pp, 2001

In Situ Expedient Test Methods to Determine Geotechnical Properties of Dredged Materials
U.S. Army Corps of Engineers, ERDC TN-DOER-N12, 11 pp, 2001

Predicting Geotechnical Parameters of Fine-grained Dredged Materials Using the Slump Test Method and Index Property Correlations
U.S. Army Corps of Engineers, ERDC TN-DOER-D1, 15 pp. 2004

Variability in Geotechnical Properties of Sediments and Dredged Materials
U.S. Army Corps of Engineers, ERDC TN-DOER-D2, 16 pp, 2004

Re-Suspended Sediment

Literature Review of Effects of Resuspended Sediments Due to Dredging Operations
Anchor Environmental CA, L.P.
Los Angeles Contaminated Sediments Task Force, 140 pp, 2003

The layout of this paper first briefly presents the types of equipment commonly used during dredging. Next, a description of the mechanisms of sediment resuspension is provided as well as a presentation of typical dredging project sediment resuspension concentrations. Next, the literature pertaining to documented physical and chemical effects to the aquatic environment caused by resuspended sediments is presented, followed by a discussion on available best management practices. Lastly, a conclusions and recommendation section describes possible future data needs for the region.

Protocol for the Field Measurement of Sediment Release from Dredgers: A Practical Guide to Measuring Sediment Release from Dredging Plant for Calibration and Verification of Numerical Models
Wallingford, H.R., Ltd and & Dredging Research Ltd, 83 pp, 2003

This protocol is an evolving document that will occasionally be updated as field experience is gained. Some of the techniques described here have not yet been fully evaluated. In particular, the sampling of trailer overflow using the flow-through samplers described in Section 7.2 (as opposed to simple 'bottle' samplers has not yet been clearly demonstrated to be necessary. The results of the Rotterdam experiment during which the flow-through samplers were used are still being analyzed but preliminary indications are that such samplers are required.

Rates and Effects of Sedimentation in the Context of Dredging and Dredged Material Placement
U.S. Army Corps of Engineers, ERDC TN-DOER-E19, 12 pp, 2005

Sedimentation: Potential Biological Effects of Dredging Operations in Estuarine and Marine Environments
U.S. Army Corps of Engineers, ERDC TN-DOER-E20, 14 pp, 2005

Silt Curtains as a Dredging Project Management Practice
U.S. Corps of Engineers, ERDC TN-DOER-E21, 18 pp, 2005

Case Studies

Engineering Performance Standards Hudson River PCBs Superfund Site Volume 5: Appendix - Case Studies of Environmental Dredging Projects
USEPA, Region 2, 146 pp, 2004

Field Study on Environmental Dredging Residuals: Ashtabula River, Volume I. Final Report
Foote, E., G. Durell, S. Williams, J. Hardin, M. Mills, R. Brenner, C. Jones, and J. Magalen.
EPA 600-R-10-126, 82 pp, 2010

Extensive monitoring studies and physical and chemical measurements were carried out prior to, during, and after dredging along a 1,100-ft study area of the Ashtabula River. In addition to estimating the volume and concentration of contaminated sediment residuals remaining after completion of dredging, field efforts focused on comparing pre- and post-dredging sediment mass and concentration characterization data to assess the PCB concentration relationship of the residual sediment to the contaminated material removed. The residuals data indicated consistent sediment and PCB mass removals greater than or equal to 95%. The data also revealed that the sediment residuals layer was composed of more highly contaminated sediments originating from higher elevations in the vertical sediment profile, rather than the lower-concentration sediments removed from immediately above the final post-dredge sediment surface.

Final Engineering Performance Standards Hudson River PCBs Superfund Site (April 2004)
USEPA, Region 2, 1370 pp. 2004

The Hudson River ROD calls for targeted environmental dredging of approximately 2.65 million cubic yards of PCB contaminated sediment from the Upper Hudson River. These five volumes develop the performance standards for dredging related resuspension, residuals, and productivity.

Investigations of Controlling Factors for Air Emissions Associated with the Dredging of Indiana Harbor and Canal (IHC) and CDF Operations
Thibodeaux, L.J., K.T. Valsaraj, R. Ravikrishna, K. Fountain, and C.L. Price.
ERDC/EL TR-08-17, 142 pp, 2008

In an investigation of specific factors that control air emissions associated with the dredging of IHC sediments and related CDF operations, three primary objectives were proposed: (1) measurements of Henry's Law constants and sediment/water desorption constants for various chemicals from IHC sediments; (2) measurement of volatile emissions from IHC sediments exposed to air; and (3) the reformulation of models developed for estimating air emissions from contaminated sediments dredging and handling activities. The data produced during these investigations have been compiled into this final report.

Methods and Metrics for Evaluating Environmental Dredging at the Ashtabula River Area of Concern (AOC)
Mills, M., R. Brenner, J. Schubauer-Berigan, J. Lazorchak, and J. Meier.
EPA 600-R-16-322, 215, 2016

Environmental dredging relies on rapid mechanical removal of the contaminated sediment layer and subsequent off-site confined disposal. Environmental dredging was selected as the remedy of choice for remediation and cleanup of the Ashtabula River area of concern (AOC), a highly contaminated sediment site in northeastern Ohio. PCBs constituted the primary COC for this site, with PAHs and inorganic chemicals comprising secondary COCs. Dredging on this AOC was carried out from fall 2006 through fall 2007. The site was extensively characterized in the spring and summer of 2006 prior to dredging. A comprehensive evaluation and monitoring program was conducted by EPA during the dredging period, immediately following dredging in early 2008, and then through 2011 to assess long-term recovery. This report summarizes and interprets the results of the 6-year study to monitor pollutant fate and transport and ecosystem recovery through the use of bathymetry; sampling and chemical analysis of sediment, water, and indigenous fish; and deployment and follow-up retrieval and analysis of macrobenthos and passive samplers.

Review of Mechanical and Hydraulic Dredging at Two Sediment Remediation Sites
Wescott, J.
Proceedings of the Annual International Conference on Soils, Sediments, Water and Energy 16:90-99(2011)

This paper compares and contrasts the methods for sediment dredging at two sediment remediation projects for EPA's Great Lakes National Program Office: the West Branch of the Grand Calumet River in Hammond, IN, and the Ottawa River in Toledo, OH. The author focuses on the specific site conditions that influenced selection of each approach as well as lessons learned during construction activities at both locations. The Ottawa River sediments contained PCBs at concentrations both above and below 50 ppm.

SMWG Review and Analysis of Selected Sediment Dredging Projects (Revised)
Nadeau, Steven C.
The 2nd Meeting of the National Research Council Committee on Dredging Effectiveness at Superfund Megasites, June 7, 2006, Irvine, California, 129 pp, 2006

This is a PowerPoint presentation that provides detailed descriptions of approach used, equipment used, results, costs, and lessons learned on nine sites.

The U.S. EPA's Great Lakes Legacy Act Ashtabula River Clean-Up
Cieniawski, Scott
USEPA, Great Lakes Program Office, 46 pp (PPT), 2008

This is a PowerPoint presentation given to the USEPA Technical Support Program's National Sediment Forum. It contains a novel treatment system for handling PCB contaminated hydraulic dredge produced sediments.

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